CHAPTER 15

1. CHAPTER 15 Sleep and Consciousness The Neural Bases of Consciousness

2. Sleep issues and disorders • Insomnia • inability to sleep or to obtain adequate quality sleep • Must occur to the extent that the person feels inadequately rested. • Insomnia can be brought on by a number of factors, • stress. • Health issues • Lack of physical activity • Over-medicaton or medication interactions • occurs frequently in people with psychological problems, especially affective disorders. • May tie in with weight gain and obesity: people with insomnia show • Waking release of hypocretin or orexin • Lower levels of leptin and higher ghrelin levels • Orexigenic or appetite enhancing effect

3. insomnia • Many manifestations: • Delayed sleep onset • Nighttime waking • Early waking • Disruption of circadian rhythm often is cause • Normally: body temp decreases as fall asleep • If body temp still high at bedtime, takes longer or is more difficult to fall asleep • If rises too early- wake up early

4. Other disorders • Two mutations in circadian clock genes identified with insomnia: • Advanced sleep phase syndrome: early onset of sleep, early waking • Chronotype: internal clock synchronized to 24-hour day, but depends on environment as well • Are you a lark or an owl? • Delayed sleep syndrome: • Obviously, delayed getting to sleep • Often not going to bed until wee hours of morning • Treatment: stay up three hours later each day, until completely reset clock!

5. Narcolepsy • Individuals fall asleep suddenly during the daytime : go directly into REM sleep. • Cataplexy • sudden experience of one component of REM sleep – atonia – • falls to the floor paralyzed but fully awake. • Not that sleep more, but “boundaries” between sleep and wakefulness are disrupted- have sudden shifts • Why? Mutated HLA-DQ6 gene that is responsible for hypocretin receptor function • Have low or undetectable levels of hypocretin, due to loss of hypocretin secreting neurons in hypothalamus • Also an HLA-DR15 gene mutation • Treatment: stimulants; but targeting hypocretin would work better!

6. Sleep walking • Some sleep disorders, such as sleep walking, related to specific sleep stages. • E.g., Bedwetting, night terrors, and sleep walking occur during slow wave sleep. • Although sleepwalking most frequent in childhood, about 3-8% of adults sleepwalk. • Sleepwalking • at least partially genetic • Can be triggered by stress, alcohol, and sleep deprivation

7. REM SLEEP DISORDER • REM sleep behavior disorder • Individuals uncharacteristically physically active during REM sleep, • Often injure themselves or their bed partners. • Often associated with a neurological disorder, such as Parkinson’s disease or a brain stem tumor. • Why? Lewy bodies found in up to 2/3 patient’s brains • abnormal aggregates of protein that develop inside nerve cells • Inhibition of magnocelluar nucleus that normally produces atonia during sleep • Suggest that Parkinsons, brain tumors, and related disorders preceded by development of Lewy bodies in medulla • Sleep disturbances may be “soft” sign of these disorders • As disease progresses, Lewy bodies progress up into higher brain areas

8. The Neural Basesof Consciousness • Consciousness • refers to a state: a person is conscious or unconscious. • The term also used to indicate sense of conscious experience, or awareness of something. • Consciousness involves short-term memory, • Fully conscious humans have a sense of self, • requires long-term memory. • Consciousness varies in level • coma and deep anesthesia on one extreme • alert wakefulness on the other, and sleep in between.

9. Glasgow Coma Scale

10. The Neural Basesof Consciousness • Three critical components of consciousness • Awareness • Attention • Senseof self. • Altered states of consciousness include • hypnosis • trances • meditative states

12. awareness • Awareness: • abstract concept • difficult to define, more difficult to study. • Researchers focused on awareness of something. • Prefrontal cortex appears to be key player in producing awareness. • May also involve hippocampus • Hippocampus critical for declarative learning • Declarative learning, by definition, involves awareness. • Also parietal lobes: • ability to locate those objects in space which are necessary for combining features of an object into a conscious whole.

13. Binding problem • Issue of how the brain combines information from different areas into a unitary whole: how integrate all the incoming information • Brain must bind information from area to another • Numerous studies suggest: synchronization of activity across brain areas binds various elements of perception into a coherent cognitive experience. • Forming neural networks • Networks must be linked to other networks, forming larger networks • Quickly goes beyond our computational ability to work with this.

14. Experimental evidence for binding • Light paired several times with shock to the middle finger: CSL USshock • Light alone produces synchronized firing between visual cortex and somatosensory cortex where fingers represented. • Synchrony occurs in right hemisphere when shock applied to left hand • Synchrony occurs in left hemisphere when shock applied to right hand

15. attention • Attention: brain’s means of allocating limited resources by focusing on some neural inputs to the exclusion of others. • Is a physiological process • changes in attention accompanied by changes in neural activity. • When an observer attends to an object: • firing synchronizes between brain areas involved • E.g., prefrontal with parietal neurons or parietal neurons with visual areas, depending on the task. • When attention shifts, • E.g., during binocular rivalry • activity shifts from one group of neurons in the visual cortex to another, • Shifts even though stimulus inputs do not change.

16. Sense of self • Critical aspect of consciousness • The sense of self includes identity: what we refer to as “I” • sense of agency: attribution of an action or effect to ourselves. • Research suggests that damage to the anterior cingulate cortex results in diminished self awareness • Damage to right frontal-temporal cortex may produce sense of detachment from the self. • Farrer and Frith et al. • sense of agency mediated by anterior insulaand inferior parietal area.

17. Intriguing evidence: • Patients like HM • deprived of short-term memory • but have most of long term memories of past intact, • Typically have a strong sense of self. • Korsakoff’s and Alzheimer’s patients • Extensive loss of current memories, then past memories, • Greater impairment of their sense of self. • Indicates that loss of LTM means loss of who you are • Interesting: occurs in reverse order • Forget adult self and “re-enter” childhood • Eventually, lose all of oneself • like randomly tearing pages from a book until all you have left is the cover

18. Why sense of self important? • Body image contributes to a sense of self • We have identification with our body and with its parts • Identify actions that are “ours” versus “not ours” • Able to identify our thoughts/actions from those of others . • Without long-term memory: doubtful there can be a self • If there is memory, there is no past there • If there is no past, there is no sense of who the person is • A sense of self requires distinction between our self and other selves • Cannot understand other selves unless understand our self. • Mirror neurons appear critical to developing the ability to attribute mental states to others (theory of mind).

19. Mirror neurons • Neurons that fire both when one acts and when one observes the same action performed by another • the neuron "mirrors" the behavior of the other, as though the observer were itself acting. • Identified mirror neurons in primates. Dogs, birds and several other species • In humans, brain activity consistent with mirror neurons found in • premotor cortex, • supplementary motor area, • primary somatosensory cortex • inferior parietal cortex

20. Why mirror neurons? Several theories • system provides physiological mechanism for perception-action coupling • important for understanding the actions of others • also for learning new skills by imitation. • mirror systems may simulate observed actions, and thus contribute to theory of mind skills • mirror neurons critical for language abilities. • help us understand actions and intentions of others • The neural basis of the human capacity for emotions such as empathy • problems with or absence of the a mirror neuron system may underlie cognitive disorders, particularly autism and Williams syndrome

21. Sense of self = Integration of both hemispheres • Hemispherectomy: • surgical procedure that separates two cerebral hemispheres • cut the corpus callosum. • used to prevent severe epileptic seizures from crossing the midline and engulfing the other side of the brain. • Individuals with “split brain” show interesting differences: raise important questions about consciousness and the self.

22. Split brain patients and “self” • Split-brain outcomes: • language-dominant hemisphere is conscious, while other hemisphere is non-conscious automaton. • But: each hemisphere capable of consciousness, • Thus severing the corpus callosum divides consciousness into two “selves”. • Gazzaniga : Left hemisphere contains module that serves as “brain interpreter.” • integrates all cognitive processes going on simultaneously in other modules of the brain • If not have both hemispheres intact, brain interpreter cannot function normally.

23. Dissociative identity disorder • Dissociative identity disorder • formerly known as multiple personality • Disorder of the self • involves shifts in consciousness and behavior that appear to be distinct personalities or selves. • causes of this disorder are not understood, • Appears to be related to abuse • 90 to 95% of patients report childhood physical and/or sexual abuse. • individual creates alternate personalities (“alters”) as a defense against persistent emotional stress. • The alters provide escape • Also offers opportunity to engage in prohibited forms of behavior. • Suggests that under stress brain can isolate “memories” to protect the major “self”

24. So what is consciousness? ? • Most neurobiological theories of consciousness assume that consciousness requires widely distributed neuronal network. • According to some theorists • consciousness occurs when functioning of widespread networks becomes coordinated, • Enables them to share and integrate information. • Distribution of consciousness • means that there is no center of consciousness, • some researchers believe must be an executive function • Brain integrator important • area that coordinates or orchestrates activity of all the other structures.

25. Do animals show a sense of self? Frans deWall: ethologist who studies moral behavior Several studies with monkeys: do they notice and can they compare what they get versus what others get Let’s take a look: http://www.wimp.com/moralbehavior/

26. Take home message • Brain activity occurs on molecular/cellular level • Quite complicated • Huge amount of neurons firing at any time • Individual cells must form networks • Networks must work together • Must be stable yet fluid • Forms basis of “memories” throughout the brain • No “centers” in brain • Redundancy, redundancy, redundancy • Duplication of centers; multiple mechanisms control similar behaviors • Allows neuroprotection

27. Take home message • Only when brain networks “work together” in elaborate, coordinated and consistent way do we become a “person” • Damage alters who we are, what we are • But who we are is evolving and changing as our brain changes • If we don’t use a process/function, there is a danger we could lose it! • We only have one brain: use it wisely, protect it, and respect it!