question: How does the brain/body differentiate between different “unconscious” states (i.e. sleep, anesthesia, alcohol, knock out, etc) in regards to reaction, rest, and recovery, when in a basic sense, regardless of type - we simply perceive a lack of consciousness?
comment: Just to clarify, I would argue that there is consciousness during many stages of sleep. Also with a blackout there is consciousness as well. In both of those cases, no consciousness is *remembered* though.
passages: There are two common but distinct dimensions of the term "consciousness", one involving "arousal" and "states of consciousness" and the other involving "content of consciousness" and "conscious states". To be conscious "of" something, the brain must be in a relatively high state of arousal (sometimes called "vigilance"), whether awake or in REM sleep. Brain arousal level fluctuates in a circadian rhythm but these natural cycles may be influenced by lack of sleep, alcohol and other drugs, physical exertion, etc. Arousal can be measured behaviorally by the signal amplitude required to trigger a given reaction (for example, the sound level that causes a subject to turn and look toward the source). High arousal states involve conscious states that feature specific perceptual content, planning and recollection or even fantasy. Clinicians use scoring systems such as the Glasgow Coma Scale to assess the level of arousal in patients with "impaired states of consciousness" such as the comatose state, the persistent vegetative state, and the minimally conscious state. Here, "state" refers to different amounts of externalized, physical consciousness: ranging from a total absence in coma, persistent vegetative state and general anesthesia, to a fluctuating, minimally conscious state, such as sleep walking and epileptic seizure.
   Section::::Classification.
  
  Patients in such a dramatically altered state of consciousness present unique problems for diagnosis, prognosis and treatment. 
  
  Assessment of cognitive functions remaining after a traumatic brain injury is difficult. Voluntary movements may be very small, inconsistent and easily exhausted. Quantification of brain activity differentiates patients who sometimes only differ by a brief and small movement of a finger.
  
  Consciousness is a complex and multifaceted concept, divided into two main components: Arousal and Awareness.
   Section::::Global disorders of consciousness.
  
  Given the absence of any accepted criterion of the minimal neuronal correlates necessary for consciousness, the distinction between a persistently vegetative patient who shows regular sleep-wave transitions and may be able to move or smile, and a minimally conscious patient who can communicate (on occasion) in a meaningful manner (for instance, by differential eye movements) and who shows some signs of consciousness, is often difficult. In global anesthesia the patient should not experience psychological trauma but the level of arousal should be compatible with clinical exigencies.
   There are some brain states in which consciousness seems to be absent, including dreamless sleep, coma, and death. There are also a variety of circumstances that can change the relationship between the mind and the world in less drastic ways, producing what are known as altered states of consciousness. Some altered states occur naturally; others can be produced by drugs or brain damage. Altered states can be accompanied by changes in thinking, disturbances in the sense of time, feelings of loss of control, changes in emotional expression, alternations in body image and changes in meaning or significance.
   Clinicians talk about "impaired states of consciousness" as in "the comatose state", "the persistent vegetative state" (PVS), and "the minimally conscious state" (MCS). Here, "state" refers to different "amounts" of external/physical consciousness, from a total absence in coma, persistent vegetative state and general anesthesia, to a fluctuating and limited form of conscious sensation in a minimally conscious state such as sleep walking or during a complex partial epileptic seizure. The repertoire of conscious states or experiences accessible to a patient in a minimally conscious state is comparatively limited. In brain death there is no arousal, but it is unknown whether the subjectivity of experience has been interrupted, rather than its observable link with the organism. Functional neuroimaging have shown that parts of the cortex are still active in vegetative patients that are presumed to be unconscious; however, these areas appear to be functionally disconnected from associative cortical areas whose activity is needed for awareness.
   Research conducted on the effects of partial epileptic seizures on consciousness found that patients who suffer from partial epileptic seizures experience altered states of consciousness. In partial epileptic seizures, consciousness is impaired or lost while some aspects of consciousness, often automated behaviors, remain intact. Studies found that when measuring the qualitative features during partial epileptic seizures, patients exhibited an increase in arousal and became absorbed in the experience of the seizure, followed by difficulty in focusing and shifting attention.
   Medical conditions that inhibit consciousness are considered disorders of consciousness. This category generally includes minimally conscious state and persistent vegetative state, but sometimes also includes the less severe locked-in syndrome and more severe chronic coma. Differential diagnosis of these disorders is an active area of biomedical research. Finally, brain death results in an irreversible disruption of consciousness. While other conditions may cause a moderate deterioration (e.g., dementia and delirium) or transient interruption (e.g., grand mal and petit mal seizures) of consciousness, they are not included in this category.
  
  Section::::Medical aspects.:Anosognosia.
   Consciousness is of concern to patients and physicians, especially neurologists and anesthesiologists. Patients may suffer from disorders of consciousness, or may need to be anesthetized for a surgical procedure. Physicians may perform consciousness-related interventions such as instructing the patient to sleep, administering general anesthesia, or inducing medical coma. Also, bioethicists may be concerned with the ethical implications of consciousness in medical cases of patients such as the Karen Ann Quinlan case, while neuroscientists may study patients with impaired consciousness in hopes of gaining information about how the brain works.
  
  Section::::Medical aspects.:Assessment.
   Unconsciousness may occur as the result of traumatic brain injury, brain hypoxia (e.g., due to a brain infarction or cardiac arrest), severe poisoning with drugs that depress the activity of the central nervous system (e.g., alcohol and other hypnotic or sedative drugs), severe fatigue, anaesthesia, and other causes.
  
  Section::::Law and medicine.
   An altered level of consciousness can result from a variety of factors, including alterations in the chemical environment of the brain (e.g. exposure to poisons or intoxicants), insufficient oxygen or blood flow in the brain, and excessive pressure within the skull. Prolonged unconsciousness is understood to be a sign of a medical emergency. A deficit in the level of consciousness suggests that both of the cerebral hemispheres or the reticular activating system have been injured. A decreased level of consciousness correlates to increased morbidity (sickness) and mortality (death). Thus it is a valuable measure of a patient's medical and neurological status. In fact, some sources consider level of consciousness to be one of the vital signs.
   In medicine, consciousness is examined using a set of procedures known as neuropsychological assessment. There are two commonly used methods for assessing the level of consciousness of a patient: a simple procedure that requires minimal training, and a more complex procedure that requires substantial expertise. The simple procedure begins by asking whether the patient is able to move and react to physical stimuli. If so, the next question is whether the patient can respond in a meaningful way to questions and commands. If so, the patient is asked for name, current location, and current day and time. A patient who can answer all of these questions is said to be "alert and oriented times four" (sometimes denoted "A&Ox4" on a medical chart), and is usually considered fully conscious.
   Many actions in response to sensory inputs are rapid, transient, stereotyped, and unconscious. They could be thought of as cortical reflexes and are characterized by rapid and somewhat stereotyped responses that can take the form of rather complex automated behavior as seen, e.g., in complex partial epileptic seizures. These automated responses, sometimes called "zombie behaviors", could be contrasted by a slower, all-purpose conscious mode that deals more slowly with broader, less stereotyped aspects of the sensory inputs (or a reflection of these, as in imagery) and takes time to decide on appropriate thoughts and responses. Without such a consciousness mode, a vast number of different zombie modes would be required to react to unusual events.
   It has been argued that consciousness is influenced by other parts of the mind. These include unconsciousness as a personal habit, being unaware, and intuition. Phenomena related to semi-consciousness include awakening, implicit memory, subliminal messages, trances, hypnagogia, and hypnosis. While sleep, sleepwalking, dreaming, delirium, and comas may signal the presence of unconscious processes, these processes are seen as symptoms rather than the unconscious mind itself.
  
  Some critics have doubted the existence of the unconscious.
  
  Section::::Historical overview.
   This state reflects an intact brainstem and allied structures but severely damaged white and gray matter in both cerebral hemispheres. The preservation of these structures maintains arousal and automatic functions. The overall metabolism drops in average to 40-50% of the normal range. After four weeks in a vegetative state (VS), the patient is classified as in a persistent vegetative state. Here the metabolism drops to 30-40% of the normal range but seems to be a result of trans-synaptic neuronal degeneration.
  
  Although the diagnosis is problematic, the formal absence of any sign of conscious perception or deliberate action is essential.
   In medicine, consciousness is assessed by observing a patient's arousal and responsiveness, and can be seen as a continuum of states ranging from full alertness and comprehension, through disorientation, delirium, loss of meaningful communication, and finally loss of movement in response to painful stimuli. Issues of practical concern include how the presence of consciousness can be assessed in severely ill, comatose, or anesthetized people, and how to treat conditions in which consciousness is impaired or disrupted. The degree of consciousness is measured by standardized behavior observation scales such as the Glasgow Coma Scale.
  
  Section::::Etymology.
   There are two common but distinct dimensions of the term "consciousness", one involving "arousal" and "states of consciousness" and the other involving "content of consciousness" and "conscious states". To be conscious "of" anything the brain must be in a relatively high state of arousal (sometimes called "vigilance"), whether in wakefulness or REM sleep, vividly experienced in dreams although usually not remembered. Brain arousal level fluctuates in a circadian rhythm but may be influenced by lack of sleep, drugs and alcohol, physical exertion, etc. Arousal can be measured behaviorally by the signal amplitude that triggers some criterion reaction (for instance, the sound level necessary to evoke an eye movement or a head turn toward the sound source). Clinicians use scoring systems such as the Glasgow Coma Scale to assess the level of arousal in patients.
   In a minimally conscious state, the patient has intermittent periods of awareness and wakefulness. The criteria for minimally conscious state, that patients are not in a vegetative state but are not able to communicate consistently. This means, that patients have to show limited but reproducible signs of awareness of themself or their environment. This could be following of simple commands, intelligible speech or purposeful behavior (including movements or affective behavior in relation to external stimuli, but not reflexive activity).
   At present, there is no established relation between cerebral metabolic rates of glucose or oxygen as measured by PET and patient outcome. The decrease of cerebral metabolism occurs also when patients are treated with anesthetics to the point of unresponsiveness. Lowest value (28% of normal range) have been reported during propofol anesthesia. Also deep sleep represents a phase of decreased metabolism (down to 40% of the normal range)
  
  In general, quantitative PET studies and the assessment of cerebral metabolic rates depends on many assumptions.
   One of the most striking disorders of consciousness goes by the name anosognosia, a Greek-derived term meaning 'unawareness of disease'. This is a condition in which patients are disabled in some way, most commonly as a result of a stroke, but either misunderstand the nature of the problem or deny that there is anything wrong with them. The most frequently occurring form is seen in people who have experienced a stroke damaging the parietal lobe in the right hemisphere of the brain, giving rise to a syndrome known as hemispatial neglect, characterized by an inability to direct action or attention toward objects located to the left with respect to their bodies. Patients with hemispatial neglect are often paralyzed on the right side of the body, but sometimes deny being unable to move. When questioned about the obvious problem, the patient may avoid giving a direct answer, or may give an explanation that doesn't make sense. Patients with hemispatial neglect may also fail to recognize paralyzed parts of their bodies: one frequently mentioned case is of a man who repeatedly tried to throw his own paralyzed right leg out of the bed he was lying in, and when asked what he was doing, complained that somebody had put a dead leg into the bed with him. An even more striking type of anosognosia is Anton–Babinski syndrome, a rarely occurring condition in which patients become blind but claim to be able to see normally, and persist in this claim in spite of all evidence to the contrary.
   Disorders of consciousness are medical conditions that inhibit consciousness. Some define disorders of consciousness as any change from complete self-awareness to inhibited or absent self-awareness and arousal. This category generally includes minimally conscious state and persistent vegetative state, but sometimes also includes the less severe locked-in syndrome and more severe but rare chronic coma. Differential diagnosis of these disorders is an active area of biomedical research. Finally, brain death results in an irreversible disruption of consciousness. While other conditions may cause a moderate deterioration (e.g., dementia and delirium) or transient interruption (e.g., grand mal and petit mal seizures) of consciousness, they are not included in this category.
   Postoperative cognitive dysfunction (also known as "POCD" and post-anesthetic confusion) is a disturbance in cognition after surgery. It may also be variably used to describe emergence delirium (immediate post-operative confusion) and early cognitive dysfunction (diminished cognitive function in the first post-operative week). Although the three entities (delirium, early POCD and long-term POCD) are separate, the presence of delirium post-operatively predicts the presence of early POCD. There does not appear to be an association between delirium or early POCD and long-term POCD. According to a recent study conducted at the David Geffen School of Medicine at UCLA, the brain navigates its way through a series of activity clusters, or "hubs" on its way back to consciousness. Dr. Andrew Hudson, an assistant professor in anesthesiology states, "Recovery from anesthesia is not simply the result of the anesthetic 'wearing off,' but also of the brain finding its way back through a maze of possible activity states to those that allow conscious experience. Put simply, the brain reboots itself."
   Arousal is associated with functional brainstem neuron populations projecting to both thalamic and cortical neurons. Therefore, the assessment of reflexes (Using the Glasgow Coma Scale) is important to investigate the functional integrity of the brainstem.
  
  Awareness is thought to be related with functional integrity of the cerebral cortex and its subcortical connections.
   Because the medical staff may not know if a person is unconscious or not, it has been suggested that the staff maintain the professional conduct that would be appropriate for a conscious patient.
  
  Section::::Conscious sedation and monitored anesthesia care.
   While some state that 'altered states of consciousness can be assessed by observations and imaging of the brain such as functional magnetic resonance imaging (fMRI), computed tomography scan (CT), magnetic resonance imaging (MRI) or electroencephalography (EEG) which records the electrical brain wave activity. Imaging is most important to make a diagnosis when patient's history is unobtainable and the physical examination is not dependable' (Dandan, 2004) others state that:
  
  Section::::Neurobiological models of altered state experiences.
  
  Section::::Neurobiological models of altered state experiences.:The entropic brain hypothesis.
   Unconsciousness
  
  Unconsciousness is a state which occurs when the ability to maintain an awareness of self and environment is lost. It involves a complete or near-complete lack of responsiveness to people and other environmental stimuli.
  
  Loss of consciousness should "not" be confused with the notion of the psychoanalytic unconscious or cognitive processes (e.g., implicit cognition) that take place outside awareness, and with altered states of consciousness, such as delirium (when the person is confused and only partially responsive to the environment), normal sleep, hypnosis, and other altered states in which the person responds to stimuli.
  
presuppositions: People are unconscious when they sleep or are blacked out. Sleep and blackouts are unconscious.
corrections: People are conscious when they sleep or are blacked out but no consciousness is remembered. There is consciousness during many stages of sleep, and with a blackout.
raw_presuppositions: People are unconscious when they sleep or are blacked out. Sleep and blackouts are unconscious.
raw_corrections: People are conscious when they sleep or are blacked out but no consciousness is remembered. There is consciousness during many stages of sleep, and with a blackout.