CHAPTER PREVIEW
In this chapter we turn our attention to a specific neurological function: consciousness. This is an important topic in light of speech and language being conscious processes.
IN THIS CHAPTER
In this chapter, we will . . .
■ Define the term consciousness
■ Explore the neural basis of consciousness
■ Describe how consciousness is assessed in a medical setting
■ Describe different disorders of consciousness
■ Explore the speech-language pathologist's role when helping patients with disorders of consciousness
LEARNING OBJECTIVES
1. The learner will define consciousness, core consciousness, and extended consciousness.
2. The learner will list and describe the primary neurological structures thought to be involved in consciousness.
3. The learner will list and briefly describe at least five specific disorders of consciousness.
4. The learner will list and describe the various mind-brain theories.
5. The learner will articulate the two main views of personhood.
CHAPTER OUTLINE
■ Introduction
■ What Is Consciousness?
■ The Neurology of Consciousness
• Neural Mechanisms of Wakefulness
• Neural Mechanisms of Core Consciousness and Extended Consciousness
■ Assessing Consciousness
• The Glasgow Coma Scale
• The Rancho Levels of Cognitive Functioning
■ Disorders of Consciousness
• Overview of Disorders of Consciousness
• Specific Disorders of Consciousness
■ Treatment of People With Disorders of Consciousness
■ Disorders of Consciousness and Personhood
• Two Broad Views of Personhood
■ Speech-Language Pathology, Audiology, and Disorders of Consciousness
■ Conclusion
■ Summary of Learning Objectives
■ Key Terms
■ Draw It to Know It
■ Questions for Deeper Reflection
■ Case Study
■ Suggested Projects
■ References
► Introduction
Speech-language pathologists (SLPs) typically describe speech as being a conscious voluntary motor activity. To understand speech in this way, it is important to understand each of these terms. In this chapter, we will begin with the term consciousness and then consider different disorders of consciousness.
► What Is Consciousness?
The cognitive neuroscientist Daniel Dennett has called consciousness the last surviving mystery of our world (Dennett, 1992). What is consciousness? Neuroscientists think of consciousness as “the ability to be aware of self and surroundings” (Damasio & Meyer, 2009, pp. 4-5). This would mean that, as humans, we have internal, first-person, subjective, mental experiences that only we can be aware of and know. Examples of these experiences include our awareness and sense of ourselves, as well as our sensory, memory (creating and recalling), and decision-making experiences. Other people do not have access to these experiences (i.e., they are private to us), but others do have external, third-person, objective, and behavioral experiences of us. Examples include others seeing that we are awake, viewing emotional leakage (e.g., crying), watching us attending to an object or person (e.g., playing on our cell phone), and observing our behaviors (e.g., walking and talking) (Damasio & Meyer, 2009). Though others do not have access to our internal, first-person experiences, we can let others into these experiences through honest and transparent communication. This is what psychologists specialize in—accessing our first-person, private experiences in order to help us understand these experiences better, identifying unhealthy mental experiences (e.g., suicidal thoughts), and shaping these into healthier experiences.
There are two basic varieties of consciousness: core consciousness and extended consciousness. Core consciousness is the simpler of the two and involves our sense of ourselves in the here and now (i.e., at this very moment), objects in the world, and our relationship to those objects. For example, right now I have a sense of myself sitting at the computer typing on a keyboard. This is considered the “core self,” and it is dependent on being awake (i.e., wakefulness). Extended consciousness is more complex and involves our sense of self in the flow of time. We think of ourselves in the past and anticipate ourselves living in a future. This form of consciousness is known as the “autobiographical self,” and it depends on longer-term memory, whereas core consciousness does not. Extended consciousness obviously depends on intact core consciousness.
Philosophers use slightly different terms and speak of creature consciousness versus mental-state consciousness. Creature consciousness refers to the consciousness of whole organisms, whereas mental-state consciousness means consciousness as it relates to particular mental states and processes. Features of creature consciousness might include sentience (i.e., sensing the world around you), wakefulness, selfconsciousness (i.e., being aware that you are aware), subjective experience (i.e., what is it like to be me?), and transitive consciousness (i.e., being conscious of various things) (Van Gulick, 2011). Mental-state consciousness would involve having a desire for something, like cake, and being able to step above the desire and reflect, “I am having a desire for cake right now.” Creature consciousness combines wakefulness and core consciousness, and mental-state consciousness is akin to extended consciousness. For our purposes, we will focus on the terms wakefulness, core consciousness, and extended consciousness and ask, when is an organism considered conscious?
► The Neurology of Consciousness
Neural Mechanisms of Wakefulness
Perhaps a place to begin discussing the neurology of consciousness is with the question: What neural structures are involved in being awake and aware? Within the center of the brainstem’s midbrain lies the reticular (“like a web”) formation (FIGURE 9-1). The reticular formation is a series of nuclei, each of which serves specific function(s). These nuclei can be divided into four groups. First are classical reticular nuclei that contain glutaminergic (glutamate) projections. Second are monoaminergic nuclei specializing in adrenaline, serotonin, and dopamine. Third are cholinergic (acetylcholine) nuclei. Lastly, the reticular formation contains what are called autonomic nuclei that innervate the viscera (Damasio & Meyer, 2009; Parvizi & Damasio, 2001). Two of these nuclei, the classical reticular nuclei and the cholinergic nuclei, appear important in wakefulness. Glutaminergic projections from the classical reticular nuclei travel to the intralaminar nuclei of the thalamus, which the thalamus then projects to much of the cerebral cortex. Glutamate is excitatory, so it helps to stimulate cortical wakefulness. At the same time, cholinergic projections to the reticular thalamic nuclei hinder sleep.
FIGURE 9-1 The reticular activating system.
Overall, the more anterior parts of the reticular formation modulate cerebral arousal and activity by controlling the responsiveness of cortical neurons, while the more posterior parts are involved in premotor functions, such as reflexes like sneezing and hiccupping (Purves et al., 2004). Damage to the reticular formation can lead to coma and other disorders of consciousness, which strongly suggests that it plays a role in consciousness through what is called the ascending reticular activating system. Putting the pieces together from the previous paragraph, this system begins in the midbrain’s reticular formation and radiates out to the cerebral cortex through the thalamus, specifically through the intralaminar nuclei of the thalamus, in order to activate and coordinate the cerebral cortex for conscious experience. In reality, this system is still not well understood, being much more complicated than outlined here, probably involving other nuclei and nonthalamic pathways (Parvizi & Damasio, 2001). One can conclude that, though not well understood, the reticular formation does play an important role in consciousness (Blumenfeld, 2009). Massimini, Ferrarelli, Huber, Esser, Singh, and Tononi (2005) suggested that cortical connectivity is also crucial to consciousness. They examined the interconnectivity of cortical function in patients in deep sleep, a non-rapid eye movement sleep state in which a person is unconscious, and found that cortical interconnectivity is severely limited during deep sleep as compared to wakefulness.
Neural Mechanisms of Core Consciousness and Extended Consciousness
Damasio (1999) suggested that large portions of the cingulate cortex and its projections to almost all cortical regions are the crucial neural mechanism behind core consciousness’s generation of our sense of self. Extended consciousness depends on those neural mechanisms responsible for working memory and explicit memory (e.g., semantic and episodic memory) (Damasio & Meyer, 2009). These mechanisms would include at least the prefrontal cortex, the anterior cingulate cortex, the parahippocampal region, and the hippocampal formation.
► Assessing Consciousness
As we have already discussed, there is a subjective, internal, first-person, mental perspective in being conscious and also an objective, external, third- person, behavioral perspective when it comes to consciousness. Professionals in communication sciences and disorders do not have access to other people’s first-person perspectives other than through their reporting, but we can take the third-person perspective and observe behaviors in our patients that would lead us to determine whether they are conscious or not. The challenge was to develop a standard measure that would help in establishing a consciousness baseline. This tool would allow patient-to-patient comparison in addition to tracking progress in brain-injured patients.
The Glasgow Coma Scale
In 1974, neurosurgeons Teasdale and Jennett developed the Glasgow Coma Scale (GCS), which is a 15-point scale that attempts to measure a patient’s level of consciousness. It was developed to provide clear communication regarding a patient between hospitals and to track a patient’s status upon admission with his or her ultimate outcome. The GCS was intended to supplement, rather than replace, other neurological assessments. The scale measures patient behavioral responses in three areas: eyes, motor, and verbal (TABLE 9-1).
This scale is administered by emergency medical services professionals in the field and by doctors and nurses in hospitals. The highest score a patient can receive is a 15, and the lowest score is a 3. A score more than 13 indicates possible minor brain injury; a score of 9 through 12 indicates moderate brain injury.
|
TABLE 9-1 The Glasgow Coma Scale |
|
|
Eye Opening [E] |
|
|
Spontaneous (open before a stimulus is given) |
E4 |
|
To sound (open after spoken or shouted request) |
E3 |
|
To pressure (open after squeezing fingertip stimulus) |
E2 |
|
None (no opening at any time; no interfering factor [IF]*) |
E1 |
|
Not testable (cannot test due to IF) |
NT |
|
Verbal Response [V] |
|
|
Oriented (correctly gives name, place, and date) |
V5 |
|
Confused (not oriented but communication coherent) |
V4 |
|
Words (intelligible single words) |
V3 |
|
Sounds (only moans or grunts) |
V2 |
|
None (no audible response; no IF) |
V1 |
|
Not testable (cannot test due to IF) |
NT |
|
Motor Response [M] |
|
|
Obeys commands (obeys two-step commands) |
M6 |
|
Localizing (brings hand above clavicle to stimulus) |
M5 |
|
Normal flexion (bends arm at elbow rapidly, normal) |
M4 |
|
Abnormal flexion (bends arm at elbow abnormally) |
M3 |
|
Extension (extends arms at elbow) |
M2 |
|
None (no movement in arms; no IF) |
M1 |
|
Not testable (cannot test due to IF) |
NT |
interfering factors (IF) include drugs, cranial nerve injuries, intoxication, hearing impairment, intubation, tracheostomy, limb or spinal cord injuries, aphasia, dementia, psychiatric conditions, ocular trauma, orbital swelling, and language and culture differences.
Data from: Teasdale, G. (2014). The Glasgow ComaScale aid. Retrieved from http://www.glasgowcomascale.org/download-aid/ Scores of 3 to 8 indicate severe head injury accompanied by significant changes in consciousness (e.g., a score of 3 indicates a deep coma or brain death). The majority of patients fall within the mild brain injury category (TABLE 9-2).
Although SLPs and audiologists do not administer this scale, they do consider GCS scores in their assessments of patients. A trauma center that treats people with traumatic brain injury might have the SLP assess every patient who has sustained a traumatic blow to the head. In the course of this assessment, the SLP might look at a patient’s GCS score in the field and then upon admission to the hospital. The GCS might be a part of the screening where patients with a score of 14 or 15 pass, but all patients scoring below 13 fail and are followed for a time by the SLP. Of course, there are other factors to be considered before passing or failing a patient during a screening, but the GCS may play an important role.
|
TABLE 9-2 The Predictive Value of the Glasgow Coma Scale (Based on 34,977 Patients From 2003 to 2013) |
||
|
GCS Score |
Brain Injury Severity |
% of Patients (% who died) |
|
13-15 |
Mild brain injury |
71% (8%) |
|
9-12 |
Moderate brain injury |
12% (20%) |
|
3-8 |
Severe brain injury |
22% (46%) |
Data from: Teasdale, G., Maas, A., Lecky, F., Manley, G., Stocchetti, N., & Murray, G. (2014). The Glasgow Coma Scale at 40 years: Standing the test of time. The Lancet Neurology, 13(8), 844-854.
|
TABLE 9-3 Relationship of the Glasgow Coma Scale to Other Brain Injury Indicators |
|||||
|
Brain Injury Level |
GCS Score |
Loss of Consciousness |
Alteration of Consciousness |
Post-traumatic Amnesia |
Structural Brain Injury |
|
Mild |
13-15 |
0-30 minutes |
<24 hours |
<24 hours |
Normal |
|
Moderate |
9-12 |
30 minutes to 24 hours |
>24 hours |
24 hours to 7 days |
Abnormal |
|
Severe |
3-8 |
>24 hours |
>24 hours |
>7 days |
Abnormal |
Data from: Kimbarow, M.L. (2016). Cognitive-communicative disorders (2nd ed.). San Diego, CA: Plural Publishing.; Teasdale, G., Maas, A., Lecky, F., Manley, G., Stocchetti, N., & Murray, G. (2014). The Glasgow Coma Scale at 40 years: Standing the test of time. The Lancet Neurology, 13(8), 844-854.
Another situation could be if an SLP were asked to do a bedside swallowing evaluation on a patient and, upon evaluation, finds the patient has a GCS score less than 9 and an altered state of consciousness. Such a patient would most likely not be a good candidate for a swallowing examination, especially one that involves other personnel like for a videofluoroscopic exam.
In addition to the GCS, there are other predictors of brain injury and the resulting disorders of consciousness. Some of these include loss of consciousness, alterations in consciousness, post-traumatic amnesia, and the presence or absences of structural brain injury (TABLE 9-3). Imaging technology is used to assess structural brain injury. Electroencephalography (EEG), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI) can all be used to assess brain function in patients suffering from disorders of consciousness. Special attention in this section will be paid to those structures known to play a role in consciousness, such as the midbrain and its reticular formation.
The Rancho Levels of Cognitive Functioning
In terms of tracking a person’s emergence from coma, the Rancho Levels of Cognitive Functioning (RLCF) scale is a helpful tool to describe the process of recovery by tracking the behaviors the patient is and is not evidencing. There are eight cognitive levels, the lowest being one and the highest being eight (TABLE 9-4).
Cognitive Level I—No Response
At this level of the RLCF scale, patients are comatose. They are unresponsive to visual, auditory, and tactile stimuli. They also do not respond when their own limbs are moved (e.g., when the physical therapist does passive range-of-motion exercises).
Cognitive Level II—Generalized Response
This level describes beginning emergence from coma, when patients begin to respond to stimuli, but responses are slow, delayed, and often inconsistent. Their responses are also very general and not specific to the stimuli. For example, if a physical therapist begins to move the arm, the patient might start chewing, a response hardly connected with the stimulus. Patients at this level do not respond to verbal commands.
Cognitive Level III—Localized Response
When responses to stimuli become more specific, patients have entered the third level of the RLCF scale. These patients will not have a normal sleep-wake cycle but rather will sleep on and off throughout the day. When awake, their reactions to stimuli are more appropriate. For example, if their loved one talks to them, they might turn their head toward the side where the loved one is standing. Patients also begin to recognize their loved ones and will inconsistently follow simple commands, like “squeeze my hand.” Verbal responses will begin to emerge, usually limited to saying “yes” and “no” in response to yes/no questions, though these responses may not be very accurate.
Cognitive Level IV—Confused, Agitated
This level is probably the most disconcerting level for family members to watch. Patients are disoriented and fearful and do not understand that people are trying to help them. They are highly focused on basic needs, like eating or going to the bathroom. They will overreact to stimuli, sometimes by thrashing around and hitting or through verbal abuse. Again, this is a very troubling stage for loved ones to experience, but it is important to counsel them that it actually marks progress in coma emergence.
|
TABLE 9-4 The Rancho Levels of Cognitive Functioning |
||
|
Rancho Level |
Level Title |
Description |
|
Cognitive Level I |
No response |
Unresponsive to visual, auditory, and tactile stimuli |
|
Cognitive Level II |
Generalized response |
General responses not specific to the stimuli |
|
Cognitive Level III |
Localized response |
Responses more specific to the stimuli |
|
Cognitive Level IV |
Confused, agitated |
Disoriented, fearful, and easily agitated |
|
Cognitive Level V |
Confused, inappropriate, nonagitated |
Disoriented with poor memory skills, but not agitated; confabulates |
|
Cognitive Level VI |
Confused, appropriate |
Some level of disorientation; completes some activities of daily living with assistance; impulsive; cannot predict potential results of an action |
|
Cognitive Level VII |
Automatic, appropriate |
Oriented; behaves appropriately in familiar settings; judgment impaired (e.g., unrealistic about the future) |
|
Cognitive Level VIII |
Purposeful, appropriate |
Oriented; appropriate in social situations; has insight into impairments; abstract reasoning and judgment may still be impaired in new, unfamiliar situations |
Data from Hagen, C., Malkmus, D., & Durham, P (1979). Levels of cognitive functioning, rehabilitation of the head injured adult: Comprehensive physical management. Downey, CA: Professional Staff Association of Rancho Los Amigos National Rehabilitation Center.
Cognitive Level V—Confused, Inappropriate, Nonagitated
The second half of the scale is typically much more encouraging to family members because they begin to see the person they have known before the injury. At the fifth level, patients are still disoriented, but they are no longer agitated. They easily become overstimulated and require frequent rest breaks in therapy. These patients have poor memory skills and will sometimes confabulate to fill in their memory gaps, which is obviously inappropriate in normal daily life. They begin to complete tasks of daily living, like brushing their teeth, but often need step-by-step help to do so.
Cognitive Level VI—Confused, Appropriate
The next level describes patients who are still disoriented, but less so than at the previous levels. They will typically know the year and month but might be confused as to the day of the week or time. Patients will know they are in a hospital because of a brain injury, but their focus is more on physical problems than on issues in communication and cognition.
Memory issues will make it difficult to remember details from conversations or reading materials. They can complete activities of daily living with minimal assistance, but they remain impulsive, often acting without thinking about the consequences of actions.
Cognitive Level VII—Automatic, Appropriate
Patients at this level of the RLCF scale can follow a schedule and complete activities of daily living independently but have difficulty creating, completing, and assessing goals. They may also be unrealistic about future plans and activities, given their deficits. Cognitive processing speed is still slow, and stressful or unfamiliar situations may be frustrating.
Cognitive Level VIII—Purposeful, Appropriate
The final level involves patients who not only realize they have cognitive issues but also are beginning to compensate for those difficulties. For example, they may begin to use writing notes as a way to compensate for memory loss. At this point, they might be ready to take a driving examination or vocational evaluation. These patients’ thinking will still be slower than normal, and they may need guidance in making decisions, especially in new situations. Level VIII patients are not normal. They still have cognitive deficits, but their thinking has improved to such a degree that new friends and acquaintances may not notice their cognitive deficits.
► Disorders of Consciousness
An Overview of Disorders of Consciousness
Patients who suffer brain injury and end up in a comatose state will either die or emerge from that state into another state within about 3 weeks postinjury.
Unlike Hollywood movies in which characters wake up from a coma like someone waking up from a nap, emergence from coma is a slow and difficult process, as described by the RLCF scale. Patients will transition from a comatose state into one of four states: chronic coma (rare), persistent vegetative state, minimally conscious state, or locked-in syndrome (FIGURE 9-2) (Blumenfeld, 2009).
FIGURE 9-2 Disorders of consciousness.
Modified from Nad, L., Monti, M. M., Cruse, D., Kubler, A., Sorger, B., & Goebel, R., . . . Owen, A. M. (2012). Brain-computer interfaces for communication with nonresponsive patients. Annals of Neurology, 72, 312-323.
|
TABLE 9-5 Comparison of Different Disorders of Consciousness to Sleep |
||||
|
Purposeful Response to Stimuli |
Brainstem Reflexes |
Sleep-Wake Cycle |
EEG Patterns |
|
|
Brain death |
No |
No |
No |
Flat |
|
Coma |
No |
Yes |
No |
Severely depressed |
|
PVS |
No |
Yes |
Yes |
Severely depressed |
|
MCS |
Yes, at times |
Yes |
Yes |
Variable |
|
LIS |
Yes (eyes) |
Yes |
Yes |
Normal |
|
Sleep |
Yes, at times |
Yes |
Yes |
Normal sleep patterns |
Abbreviations: EEG, electroencephalographic; LIS, locked-in syndrome; MCS, minimally conscious state; PVS, persistent vegetative state. Data from: Blumenfeld, H. (2009). Neuroanatomy through clinical cases. Sunderland, MA: Sinauer Associates.
FIGURE 9-3 Levels of brain function in different disorders of consciousness. A. Brain death results in no brain function in the cortex, subcortex, or brainstem. B. Coma results in severely depressed function in the cortex, subcortex, and reticular activating system of the brainstem. C. Persistent vegetative state results in severely depressed cortical function, but variably depressed function in the subcortex and reticular activating system. D. Minimally conscious state results in variably depressed function in the cortex, subcortex, and reticular activating system.
Each of these conditions can be compared and contrasted through considering how responsive patients are to stimuli (e.g., “open your eyes”), whether brainstem reflexes are present (e.g., pupillary light reflex), whether there is some assemblage of a sleep-wake cycle, and the quality of the patient’s EEG patterns (TABLE 9-5). A patient is considered to have experienced brain death when there are no purposeful responses to stimuli, no brainstem reflexes, no sleep-wake cycle, and there are flat EEG patterns. Patients in a coma do not respond purposefully to stimuli but demonstrate brainstem reflexes (e.g., pupil constricts with introduction of a light source). Comatose patients do not have a sleepwake cycle and demonstrate EEG patterns, though they are severely depressed. Persistent vegetative state (PVS) patients resemble comatose patients with one difference—they demonstrate a sleep-wake cycle. Minimally conscious state (MCS) patients can be thought of as being somewhere between PVS and fully conscious in that they transition between these two states. They at times respond purposefully to stimuli, but inconsistently. They also demonstrate brainstem reflexes and a sleep-wake cycle. Like their inconsistent responses to stimuli, their EEG patterns are variable depending on what state (PVS versus conscious) they are tending toward. Patients with locked-in syndrome (LIS) may be the most tragic in that they are fully aware, conscious people locked inside bodies that do not work (Blumenfeld, 2009).
In addition to Table 9-5, FIGURE 9-3 compares brain death, coma, PVS, and MCS in terms of overall brain function. Brain death results in absent function in the cerebral cortex, diencephalon, brainstem, or cerebellum. Coma results in severely depressed function in the cerebral cortex, diencephalon, and reticular formation. PVS results in severely depressed function in the cerebral cortex, but variable function in the diencephalon and the reticular formation. MCS involves variable depressed function in the cerebral cortex, diencephalon, and reticular formation.
Earlier, three aspects of consciousness were introduced: wakefulness, core consciousness, and extended consciousness. Using this grid, one can organize the various disorders of consciousness just surveyed. Conditions characterized by impaired wakefulness and core consciousness include general anesthesia, coma, and slow-wave sleep (or deep sleep). Conditions in which there is persistent wakefulness, but impaired core consciousness, include PVS, akinetic mutism, and some forms of epilepsy. Finally, patients with persistent wakefulness and core consciousness, but impaired extended consciousness, would be those with global amnesia and Alzheimer disease (Damasio & Meyer, 2009).
Specific Disorders of Consciousness
Now that an overview of some disorders of consciousness has been completed, it is time to survey these conditions more comprehensively. In addition to coma, brain death, PVS, MCS, and LIS, we will look at other conditions in which consciousness may be an issue, including dementia, aphasia, and epilepsy. In addition, two strange experiences (out of body and near death) will be touched on, because these also have implications for consciousness. Because some patients may report these odd experiences, it is good for SLPs and audiologists to be aware of them so they are not surprised and can help patients process these experiences.
Coma
Coma is a state in which a person is unarousable and does not make meaningful responses to stimuli in the environment. The person does not have any of the following: wakefulness, core consciousness, or extended consciousness. The GCS score would be a E2-V4-M2 or less (Pryse-Phillips, 2009). Neurologically, coma is due to either a damaged reticular activating system or global depression of cortical activity or both. Conditions that can produce this type of neurological damage include stroke, tumors, metabolic and nutritional disorders, toxins, central nervous system infections, seizures, trauma, and temperature-related conditions (hyperthermia or hypothermia). LIS mimics coma to the untrained eye, but patients with it are wakeful and have both core and extended consciousness. LIS looks like coma because people with it cannot interact with their environment due to full-body paralysis (Young, 2009).
Diagnosis of coma begins with an in-depth history taken from the family as well as a thorough neurological exam, including blood work, neuroimaging, lumbar puncture, and EEG. Comatose patients display brain wave patterns on EEG, but they are depressed. Supportive care in the form of ventilation and nutrition/ hydration are key in keeping patients relatively healthy while in a coma. With 3 days of initial observation, a patient’s outcome can be predicted. Poor outcomes are associated in part with absent ocular reflexes. For example, an absent pupillary light reflex and absent corneal reflex are associated with a poor outcome.
The pupillary light reflex is assessed by flashing light into the eyes and looking for constriction of the pupils. The corneal reflex is tested by lightly touching the cornea with a wisp of cotton, which produces a defensive blinking response. In addition to these ocular reflexes, an absent response to noxious stimuli and suppressed EEG patterns are consistent with poor outcomes (Bass & Gettleman, 2009). Comatose patients will typically emerge from their coma within 3 weeks or transition into one of the other disorders mentioned in this chapter (i.e., brain death, MCS, or PVS) (Young, 2009).
Brain Death
Brain death (also known as cerebral death) is the irreversible cessation of clinical function of the brain, involving the cerebral cortex and the brainstem (Pryse-Phillips, 2009). The clinical functions intended in this definition include respiration, circulation, and neuroendocrine control, as well as awareness. Not every neuron needs to be dead, but these major, life-sustaining systems have ceased functioning and the person is dead (Bernat, 2009). Like coma, wakefulness is absent, as are core and extended consciousness. Unlike coma, brain waves are flat on EEG, meaning there is no cortical or subcortical activity. GCS scores are E1-V1-M1. The criteria for the clinical determination of brain death are presented in TABLE 9-6, as is the process of declaring someone brain dead.
Persistent Vegetative State
PVS is defined as wakeful unawareness. Though wakefulness is present, there is no core or extended consciousness. The eyes may be open and even appear to briefly track, but there are no higher cortical functions like cognition or language. GCS score would be approximately E4-V4-M1. The diagnostic criteria for PVS are as follows (Pryse-Phillips, 2009):
■ There is no evidence of awareness of self or surroundings.
■ Reflexive or spontaneous eye opening may be present.
■ There is no comprehensible speech or mouthing of words.
■ There may be smiling, frowning, and even crying, but unconnected to a stimulus.
■ Sleep-wake cycle is present.
■ Brainstem and spinal cord reflexes are variable.
■ There is no purposeful motor activity, though patient may withdraw from unpleasant stimuli.
■ Cardiorespiratory functions are usually intact, but the patient is incontinent.
PVS is often challenging to diagnose. First, how long does a person need to demonstrate PVS symptoms before PVS is officially declared? One month? One year? Second, PVS is often confused with MCS or LIS because patients are noncommunicative in all three conditions. For example, a Belgian man was misdiagnosed as being in a PVS for 23 years. After neuroimaging was completed two decades after his injury, doctors found him to be fully aware and conscious (Hall, 2009). Monti et al. (2010) report that one in five patients diagnosed as in a PVS may actually be fully aware, like this Belgian man. Others may actually be in an MCS.
Minimally Conscious State
Patients with MCS have severely altered consciousness but do demonstrate minimal behavioral evidence that they are aware of self and their environment. In other words, they have periods of not only wakefulness but also core consciousness. The extent of their extended onsciousness is unknown. Their GCS score would be about a E4-V6-M2 or E4-V6-M3. Patients have been said to emerge from MCS when they regain the ability to communicate functionally with others.
The patient in an MCS must show at least one of the following actions (Pryse-Phillips, 2009):
■ Follow simple commands, though they may be inconsistent.
■ Respond with gestures or yes/no answers, though they may be inaccurate.
■ Speak intelligibly at times.
■ Demonstrate purposeful behavior (e.g., crying) that is congruent with environmental stimuli.
■ Perform sustained eye tracking of environmental stimuli (e.g., loved one’s face).
MCS is an important diagnostic category because it distinguishes these patients from those with PVS or coma. TABLE 9-7 summarizes some of the key differences among MCS, PVS, and coma.
TABLE 9-6 The Clinical Determination of Brain Death
|
■ Diffuse brain damage with coma and apnea ■ Structural brain lesion ■ No reversible metabolic or toxic conditions ■ Physicians treating have appropriate training |
■ Coma with no ■ Findings confirmed by two separate exams responsiveness ■ Second exam omitted if confirmatory test ■ Absent brainstem reflexes (e.g., EEG) performed (e.g., pupillary light reflex) ■ Patient declared dead after second exam or ■ Breathing suspension confirmatory test (apnea) in presence of ■ Family offered opportunity for organ donation elevated carbon dioxide ■ Medical record reflects test results and declaration levels (hypercapnea) of death |
Data from: Bernat, J. L. (2009). Brain death. In S. Laureys & G. Tononi (Eds.), The neurology of consciousness. London, UK: Elsevier.
TABLE 9-7 Comparison of Minimally Conscious State (MCS), Persistent Vegetative State (PVS), and Coma
|
Behavior |
MCS |
PVS |
Coma |
|
Eye opening |
Spontaneous |
Spontaneous |
None |
|
Spontaneous movement |
Automatic/object manipulation |
Reflexive/patterned |
None |
|
Response to pain |
Localization |
Posturing/withdrawal |
Posturing/none |
|
Visual response |
Object recognition/pursuit |
Startle/pursuit (rare) |
None |
|
Affective response |
Contingent |
Random |
None |
|
Commands |
Inconsistent |
None |
None |
|
Verbalization |
Intelligible words |
Random vocalization |
None |
Data from: Giacino, J. T., & Schiff, N. D. (2009). The minimally conscious state: Clinical features, pathophysiology, and therapeutic implications. In S. Laureys & G. Tononi (Eds.), The neurology of consciousness. London, UK: Elsevier.
Locked-in Syndrome
LIS was a relatively unknown condition until Jean-Dominique Bauby published his memoir The Diving Bell and the Butterfly in 1997. A film version of the same title was released in 2007. Bauby suffered a stroke in the ventral pons region of his brainstem and acquired LIS, which is characterized by total immobility but preserved wakefulness, core consciousness, and extended consciousness. A patient’s GCS score would appear to be E4-V2-M1, but because of the whole-body paralysis, motor and verbal responses may be challenging to assess. In reality, these patients have a GCS score of E4-V6-M5 if they can obey commands with their eyes and communicate with others through a compensatory device like an alphabet board, as Bauby did.
Most LIS patients demonstrate sustained opening and movement of the eyes, quadriplegia or quadriparesis, anarthria (inability to produce known words), and aphonia (inability to speak) or hypophonia (inability to speak at normal volume). Their cognitive skills are intact. There are different forms of LIS. Classical LIS involves total body immobility but with preserved eye movements or blinking. Bauby acquired this form. Incomplete LIS is characterized by some very limited voluntary movement. Total LIS is the most devastating, with complete immobility of the body and the eyes. Any of these forms may be confused with PVS, MCS, or coma.
Dementia
Dementia refers to an acquired, usually progressive cognitive deterioration. Alzheimer disease (AD) is the most common form of dementia, affecting 5% of patients 65 years and older and almost 50% of people 85 years or older (Pietrini, Salmon, & Nichelli, 2009). The disease is caused by microscopic changes to cortical cells in the form of plaques, vacuoles, and neurofibrillary tangles (Pryse-Phillips, 2009).
People with AD progress through three stages of the disease: early, middle, and late. In the early stage of AD, patients have normal motor abilities but begin to have memory problems. In the middle stage, they have increasing problems with memory and other cognitive functions, including language. The late stage of the disease is characterized by severe cognitive deficits and deteriorating motor ability (Manasco, 2014). In terms of consciousness, wakefulness is preserved in the early through middle stages of the disease and will be affected in the later stages of AD. Core consciousness will follow the same pattern. It is extended consciousness that begins to be assaulted in the early stage of the disease as the autobiographical self begins to deteriorate under the weight of the disease.
Aphasia
Earlier in this chapter, we said that extended consciousness “depends on memory” and that our ability to share our memories depends on language. We have already seen that in AD, extended consciousness slowly declines as the disease progresses and impairs memory and language. AD patients lose the autobiographical self because they can no longer remember themselves in the past nor picture their future.
Aphasia is a multimodality acquired language disorder. People with this condition have impaired receptive and/or expressive language. The question is, when language is impaired, is extended consciousness impaired? Is a person with aphasia wakeful? Does he or she have core consciousness? Just spend 5 minutes with someone with aphasia and you will see that he or she is indeed awake and has a sense of his or her self in relationship to objects in the world.
Extended consciousness and the autobiographical self do appear to be preserved in aphasia. People who have experienced temporary aphasia due to transient ischemic attacks or hematomas have been able to report on their experiences with great detail and clarity. They note that thinking and recall were intact during the aphasic period. Some also report thinking about their future and what it would mean if the aphasic condition became a permanent part of life (Lazar, Marshall, Prell, & Pile-Spellman, 2000; Taylor, 2009).
Epilepsy
Epilepsy involves recurrent electrical storms in the brain that are involuntary and episodic in nature. They suddenly impair consciousness for short periods of time. Sufferers are awake during these events, but core and extended consciousness can both be impaired, depending on the type and severity of the seizure.
Out-of-Body Experiences
Out-of-body experiences (OBEs) are the experience of wakeful disembodiment. People feel as if they have left their physical body and even report seeing their body, sometimes with physicians trying to revive them. The following is a report from someone who experienced an OBE:
I was in bed and about to fall asleep when I had the distinct impression that “I” was at the ceiling looking down at my body in the bed. I was very startled and frightened; immediately I felt that I was consciously back in the bed again. (Irwin, 1985)
OBEs are estimated to occur in approximately 5% to 10% of the population, and the precipitating factors range from neurological disorders to drugs (Blanke & Dieguez, 2009). They occur most frequently in people with epilepsy and migraine. They have been artificially created as well. Blanke, Ortigue, Landis, and Seeck (2002) were able to stimulate OBEs in normal subjects by applying electrical current to the right temporoparietal juncture, suggesting this may be an important area for our sense of embodiment.
Near-Death Experiences
OBEs are considered a key characteristic of a more elaborate phenomenon called near-death experience (NDE). Greyson (2005) defines NDEs as “profound subjective experiences with transcendental or mystical elements, in which persons close to death may believe they have left their physical bodies and transcended the boundaries of the ego and the confines of space and time.” The incidence of NDEs is thought to be 6% to 12% in cardiac arrest patients but is unknown in other patient populations (Blanke & Dieguez, 2009).
Greyson (1983) constructed a scale to measure NDEs, which gives 16 experiential elements and their intensity (0-2) organized in four categories: cognitive, affective, paranormal, and transcendental (TABLE 9-8). The maximum score is 32, but a score of only 7 would qualify the experience as a true NDE because two of the four categories would be used to describe the experience. Using two or more categories indicates that the experience was complex, intense, and something out of the ordinary. BOXES 9- 1 and 9-2 offer further exploration of the mysterious nature of NDEs as well as the related topic of the mind-brain debate.
► Treatment of People With Disorders of Consciousness
BOX 9-1 Two Strange Cases of Near-Death Experience
Eben Alexander (2012), a Harvard neurosurgeon, contracted meningitis and fell into a coma in 2008. He asserts that his higher cortical functions ceased and that during this time he had an elaborate NDE that would score very high on the Greyson scale. Though many have criticized his account and have provided alternative, naturalistic explanations for his experience, Alexander continues to ask how a severely impaired brain such as his own could generate such an elaborate experience with vivid, detailed memories. It is a question worthy of further investigation.
This author once had a 24-year-old female patient, M. P. She was driving with a friend on a military base road when a drunken soldier struck her vehicle head on with his vehicle. M. P suffered severe head trauma and was in a coma for approximately 3 weeks. The speech-language pathology team completed coma stimulation with her over the course of the 3 weeks and then began assessing her cognitive- communicative abilities as she began to emerge. After many weeks of recovery, M. P regained the ability to converse with others and described a vivid experience, which would easily qualify as a genuine NDE using the Greyson scale. The story contained all the Greyson scale affective components and some paranormal and transcendental qualities. She also had a second experience while in the intensive care unit in a coma, but this one was an OBE only. She reported that she left her body, looked down, and saw a nurse with big blonde hair, red lips, and bright red fingernails. The therapists replied, "That sounds like Flo!”
Are stories like Alexander's and M. P's genuine disembodied NDEs or the product of oxygen deprivation or synaptic misfiring? Is there an immaterial mind as well as a material brain? If so, can the mind be separated from the body and exist independently from it? Further research should be conducted to find out. In the meantime, those SLPs and audiologists working in hospital settings should be prepared to hear about OBEs and NDEs from their patients.
|
TABLE 9-8 The Greyson Near-Death Experience Scale |
|||
|
Cognitive |
Affective |
Paranormal |
Transcendental |
|
Time distortion Thought acceleration Life review Revelation |
Peace Joy Cosmic unity Encounter with light |
Vivid sensory event Apparent extrasensory perception Precognitive visions Out-of-body experience |
Sense of otherworld environment Sense of mystical unity Sense of deceased/religious spirits Sense of border/point of no return |
Data from Greyson, B. (1983). The near-death experience scale: Construction, reliability, and validity. Journal of Nervous and Mental Disease, 185 , 327-334.
BOX 9-2 The Mind-Brain Debate
Strange phenomena like OBEs and NDEs and topics like consciousness make us think more about ourselves. Are we material only, meaning that all of our thinking and experiences are reducible to neurons and synapses? Alternatively, are we some mix of material and immaterial? In other words, do we have a soul and a body, and even more important to this text, do we have an immaterial mind and material brain? We will survey some of the different views on this topic (TABLE 9-9). We will begin with monistic (i.e., involving only one) views first and then proceed to dualistic (i.e., involving two) views.
There are three true monistic, materialistic views of human persons—reductive materialism, nonreductive materialism, and the constitution view. In reductive materialism, all of life is reduced to the material and to naturalistic explanations. As for mind, it is reduced to neurons and synaptic connections. OBEs, NDEs, and "miraculous” healings are all explained through neurophysiological processes. Most neuroscientists would probably affirm this position. Nonreductive materialism is also a materialistic view but says there is something more going on than neurons and synapses. Experiences of awe or beauty (or NDEs) do have neurological processes behind them, but these experiences cannot be reduced to mere neurological processes; rather, other processes (psychological, philosophical, and theological) are needed to explain these complex, nonreducible experiences. The constitution view is a materialistic view as well. It purports that humans are material only but are different from animals because we have a first-person perspective (i.e., extended consciousness). This first-person perspective is what makes us a person and not an animal.
Emergent dualism and holistic dualism attempt to bridge the divide between monists and dualists. Emergent dualism is the belief that the human mind emerges or arises from a combination of many brain activities. This view attempts to mediate between monism and dualism. It agrees with materialism that the mind is produced by the brain, but it also agrees with dualism that the mind is a separate entity, not completely explainable, reducible, or identifiable with specific brain functions. Holistic dualism involves the idea that human persons are integrated wholes. In other words, bodily existence is what it is to be human. There is no separation between material and immaterial because they are intertwined with each other. If there is an afterlife, it is somehow an embodied afterlife. Although both emergent and holistic dualism have the word dualism in their title, they are both essentially monistic views, but with dualistic elements.
True dualistic views include substance dualism and radical dualism. Substance dualism holds that humans are both material and immaterial and that the immaterial can exist apart from the material for a time. It is like holistic dualism in that it holds that to be human is to be embodied, but material and immaterial are not as tightly integrated. Proponents of this view would believe that OBEs and NDEs are evidence that the immaterial part can separate from the physical. In terms of brain-mind, supporters of substance dualism would believe that the brain is material and the mind is immaterial and that the mind can exist outside the body for a time. Radical dualism is similar to substance dualism, but the emphasis is on the soul; the soul is the human person and the body is just a mechanism the soul inhabits for a time. This is the "ghost in the machine" view.
The final view is idealism. Those who hold to idealism believe that the immaterial is all there is and that things in the material world (if there is a material world) are created from the immaterial. Priority is given to the mind. Idealism is actually a monistic view, but instead of everything being reducible to the body as in materialism, it is reducible to the mind. We have returned to where we started, because these views would be best presented in a circle (FIGURE 9-4).
FIGURE 9-4 The continuum of theories regarding human constitution.
There are several avenues of treatment available for people with disorders of consciousness; however, none of these have been proven to restore consciousness. One avenue is pharmacologic interventions with drugs, which has shown some promise in increasing arousal and awareness. For example, the dopaminergic drug amantadine holds some promise with patients with a traumatic etiology. A second avenue of treatment is coma stimulation (also called sensory stimulation), which can be unimodal (i.e., one sensory route) or multimodal. This approach attempts to increase arousal and awareness through systemically stimulating one or more of the five senses, thus stimulating the nervous system (Bass & Gettleman, 2009). For example, the sense of smell can be stimulated through presentation of both good (e.g., vanilla) and noxious (e.g., smelling salts) stimuli. Vision can be stimulated by showing photographs of loved ones and encouraging eye tracking. It is important to note that there is little evidence to support the efficacy of coma stimulation, though some studies have shown some increase in body movements, facial expressions, pulse rate, and respiration rate in response to auditory stimulation with audio recordings of family and friend voices (Jones, Hux, Morton-Anderson, & Knepper, 1994; Parveen, Dhandapani, Dhandapani, & Gupta, 2015; Puggina, da Silva, & Santos, 2011); other studies have not shown these effects (Walker, Eakes, & Siebe-link, 1998).
► Disorders of Consciousness and Personhood
As we have been exploring this mysterious thing we call consciousness and disorders of consciousness, the discussions raise other questions. If the definition of being brain dead presented in this chapter is followed, then we can conclude that being brain dead means that the human person is dead as well. There is only a body left. However, what about people in other not- so-clear states? Are people who are comatose or in a PVS or MCS state, or who have dementia, still people? Has the spark of humanness left them? These questions raise one of the most significant questions in life: What makes a person a person? We will use a story to help us frame this question.
Terry was only 19 years old at the time of his accident. He was married and had a baby girl named Amber. One night, while out with a friend, he lost control of his pickup truck and ran into a guardrail that hugged a curve in the road. His truck was launched straight up and came down on its tailgate. Terry’s friend walked away from the accident unharmed; however, Terry immediately fell into a coma. He did not have a scratch on his body except for a small cut on his forehead, but he was unable to take care of himself or communicate with his family. One day, after 19 years in this coma, he mysteriously woke up and began to talk to his family. His memory was impaired for recalling recent events, but it was sharp for everything that occurred before the accident. Terry was both a medical miracle and a mystery.
Why start a discussion on human personhood with this story? The answer is that this story can help us ask important questions about personhood. Is a person defined by what external behaviors he or she can or cannot do? Is a person simply a machine who is the sum of his or her parts, and when a part does not work, is he or she not a person anymore? Alternatively, is a person defined by something else, perhaps an internal essence that orders and unifies the parts a person possesses?
Two Broad Views of Personhood
There is an ongoing debate regarding human personhood, and this debate narrows down to how you define a human person. There are two basic views that revolve around this question.
The first view is to define a person as being physical only (i.e., physicalism). He or she is a body only and there is no real difference between humans and animals. Thus, a person’s abilities or disabilities become paramount in defining whether he or she is truly a person. In this view, a person is merely the sum of his or her parts, essentially a machine like a computer (Rae & Cox, 1999). Does the person have all the typical capacities, functions, and parts (e.g., consciousness, memory, the ability to communicate) we think of when we think of a human person? If the answer to this question is “yes,” then a proponent of this view might say that the person is truly a person. If someone has never attained some or all of these capacities, or if a person has lost these abilities, as in the case of Terry, is he or she still a human person?
Proponents of this view might say “no” and a practice like euthanasia becomes not only possible but in some cases necessary to increase what Princeton philosopher Peter Singer calls the total amount of happiness in the world (Will, 1999).
The second way to define a person is to say that his or her substance is a body and a soul, material and immaterial, and that something mysterious (e.g., the human spirit or essence?) orders and unifies the parts of this substance. This could be called an internal essence view. For example, a dog has dog essence, which orders and unifies its parts. It is defined by its essence, not its parts or capacities. If a dog loses the capacity to bark, is it still a dog (Beckwith, 2000)? Most reasonable people would answer in the affirmative. In addition, if a human person loses certain capacities and functions (e.g., the capacity to walk, remember things, speak), is he or she still a human person? Proponents of this view would argue that Terry, though he has severe disabilities, is still a human person.
However, what makes humans different from dogs? Singer would say “nothing” and that anyone who argues for humanity being of a different and better essence is committing speciesism, the intentional act of promoting one species over another (Will, 1999). Yet others would argue that there is something unique about humans, something that separates man and woman from beast. What do you think? Does monistic physicalism make more sense to you? Or does some kind of soul-body, mind-brain dualism make more sense? These are important and interesting questions because they do affect life decisions, like living wills and end-of-life decisions. They also may affect the way we see and work with our patients.
► Speech-Language Pathology, Audiology, and Disorders of Consciousness
SLPs may be involved with patients who have disorders of consciousness. This may take the form of completing coma stimulation with patients; assessing speech/ language function in a patient suspected of being PVS, MCS, or LIS; or assessing swallowing function. Coma stimulation is a systematic application of stimulation to a patient’s five senses with the purpose of increasing the patient’s responsiveness to stimuli. Vision can be stimulated through blinking lights, gustatory through applying different tastes, auditory through music or family voices, olfaction through applying different smells, and touch through applying different textures or temperatures to the skin. Some coma stimulation programs also add kinesthetic stimulation in the form of posture changes and/or range-of-movement exercises. Studies have been completed examining the effectiveness of this therapy approach; the results of these studies are mixed. Some studies have shown improvement in cognitive status and responsiveness and a decrease in mean length of time in a coma (Karma & Rawat, 2006; Kater, 1989; Mitchell, Bradley, Welch, & Britton, 1990; Wilson, Powell, Elliott, & Thwaites, 1991). Other studies have shown that coma stimulation does not appear to make a difference in these patients (Pierce et al., 1990; Rader, Alston, & Ellis, 1989). Audiologists may work with these populations in conducting nonbehavioral hearing assessment measures, such as auditory brainstem response.
► Conclusion
Thomas Nagel wrote an article in 1974 titled “What Is It Like to Be a Bat?” He challenged the reductionist tendencies of many neuroscientists with the fact that both humans and animals (like the bat) have conscious, personal, first-person experiences that are unique, rich, and private to us and difficult to reduce to neurons, synapses, and action potentials. Only I know what it is truly like to be Matt. You, the reader, do not know and cannot know anything of my private experience as I write this book unless I decide to reveal something to you. Even then, you will never have a true or complete first-person perspective of my first-person experience. Consciousness is certainly an interesting, complex, and mysterious topic of study.
SUMMARY OF LEARNING OBJECTIVES
The following were the main learning objectives of this chapter. The information that should have been learned is below each learning objective.
1. The learner will define consciousness, core consciousness, and extended consciousness.
• Consciousness: the ability to be aware of self and surroundings
• Core consciousness: our sense of ourselves in the here and now (i.e., at this very moment), 3. objects in the world, and our relationship to those objects
• Extended consciousness: our sense of self in the flow of time as we think of ourselves in the past and anticipate ourselves living in a future
2. The learner will list and describe the primary neurological structures thought to be involved in consciousness.
• Reticular formation: Two nuclei, the classical reticular nuclei and the cholinergic nuclei, appear important in wakefulness. Glutaminergic projections from the classical reticular nuclei travel to the intralaminar nuclei of the thalamus, which the thalamus then projects to much of the cerebral cortex. Because glutamate is excitatory, it helps to stimulate cortical wakefulness. At the same time, cholinergic projections to the reticular thalamic nuclei hinder sleep.
• Ascending reticular activating system: This system begins in the midbrain’s reticular formation and radiates out to the cerebral cortex through the thalamus, specifically through the intralaminar nuclei of the thalamus, in order to activate and coordinate the cerebral cortex for conscious experience.
The learner will list and briefly describe at least five specific disorders of consciousness.
• Coma: a condition in which the person does not respond purposefully to stimuli but does demonstrate brainstem reflexes. Comatose patients do not have a sleep-wake cycle and demonstrate EEG patterns, although they are severely depressed.
• Brain death: a condition in which the person has no purposeful responses to stimuli, no brainstem reflexes, no sleep-wake cycle, and flat EEG patterns.
• Persistent vegetative state (PVS): a condition in which the person does not respond purposefully to stimuli but does demonstrate brainstem reflexes. PVS patients have a sleep-wake cycle and demonstrate EEG patterns, although they are severely depressed.
• Minimally conscious state (MCS): a condition in which the person responds purposefully to stimuli, but inconsistently. MCS patients also demonstrate brainstem reflexes and a sleep-wake cycle. Like their inconsistent responses to stimuli, their EEG patterns are variable depending on what state (PVS vs. conscious) they are tending toward.
• Locked-in syndrome (LIS): a condition in which the person is fully aware and conscious but locked inside a body that does not work.
• Dementia: a condition in which the person is wakeful in the early through middle stages of the disease and will begin to be affected in the later stages of Alzheimer disease. Core consciousness will follow the same pattern. It is extended consciousness that begins to be assaulted in the early stage of the disease as the autobiographical self begins to deteriorate under the weight of the disease.
• Aphasia: a condition in which the person has an acquired language disorder but intact consciousness.
• Epilepsy: a condition in which the person has recurrent electrical storms in the brain that are involuntary and episodic in nature that suddenly impair consciousness for short periods of time.
• Out-of-body experience (OBE): the experience of wakeful disembodiment.
• Near-death experience (NDE): a profound subjective experience with transcendental or mystical elements, in which persons close to death may believe they have left their physical bodies and transcended the boundaries of the ego and the confines of space and time.
4. The learner will list and describe the various mind-brain theories.
• Reductive materialism: belief that all of life is reduced to the material and to naturalistic explanations
• Nonreductive materialism: belief that experiences (e.g., beauty) cannot be reduced to mere neurological processes, but rather, other processes (psychological, philosophical, and theological) are needed to explain these complex, nonreducible experiences
• Constitution view: belief that humans are material only, but are different from animals because we have a first-person perspective (i.e., extended consciousness)
• Emergent dualism: belief that the human mind emerges or arises from a combination of many brain activities
• Holistic dualism: belief that human persons are integrated wholes
• Substance dualism: belief that humans are both material and immaterial and that the immaterial can exist apart from the material for a time
• Radical dualism: belief that the soul is the human person and the body is just a mechanism the soul inhabits for a time
• Idealism: belief that all there is, is the immaterial and that things in the material world (if there is a material world) are created from the immaterial
5. The learner will articulate the two main views of personhood.
• Physicalism: belief that a person is a body only and there is no real difference between humans and animals. Thus, a person’s abilities or disabilities become paramount in defining whether he or she is truly a person.
• Internal essence view: belief that a person is both a body and a soul, material and immaterial, and that something mysterious (e.g., the human spirit or essence?) orders and unifies the parts of this substance.
KEY TERMS
Brain death Coma Consciousness Constitution view Core consciousness Creature consciousness
Emergent dualism Extended consciousness Glasgow Coma Scale (GCS)
Holistic dualism
Idealism
Mental-state consciousness
Minimally conscious state
(MCS)
Nonreductive materialism
Persistent vegetative
state (PVS)
Radical dualism
Rancho Levels of
Cognitive Functioning
(RLCF)
Reductive materialism
Reticular activating
system
Reticular formation
Substance dualism
DRAW IT TO KNOW IT
1. Draw four coronal sections of the brain and shade in impaired areas in the following
conditions: brain death, coma, PVS, and MCS (see Figure 9-3).
QUESTIONS FOR DEEPER REFLECTION
1. Pick a view of human constitution and write one
2.paragraph supporting this view.
3.Why should a communication disorders professional be aware of consciousness?
Describe the neural basis for consciousness.
CASE STUDY
Teresa is a 21-year-old female who was involved in a motor vehicle accident. She was ejected from her truck upon impact with another vehicle and suffered a significant brain injury. Her GCS in the field was E4-V6-M2 that improved to E4-V6-M3 upon admission to the emergency room. Currently, Teresa demonstrates appropriate behavior in response to environmental stimuli (e.g., will move head toward a source of sound), but arousal is inconsistent. She also attempts to utter sounds during her periods of arousal
though her speech is unintelligible. She can move all four extremities, but is inconsistent upon command.
1. Which of the following states is Teresa most likely to be in?
a. Coma
b. Minimally conscious state
c. Persistent vegetative state
d. Locked-in syndrome
2. Explain why you picked the answer you did.
3. Do you think Teresa is aware of herself and her surroundings?
SUGGESTED PROJECTS
1. Research the reticular activating system and write a short paper outlining its structure and function.
2. Obtain and read Thomas Nagel’s 1974 article “What Is It Like to Be a Bat?” (A Google search will turn up free copies.) Write a two-page reflection paper on it. Include a brief summary of the article, and state whether you agree or disagree with Nagle and why.
3. Write a two- to three-page paper on one of the disorders of consciousness presented in this chapter.
4. Explore the literature on coma/sensory stimulation and present the evidence for and against this approach.
5. Write a two- to three-page paper on how you define personhood.
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