Chaper 13: Regulating Brain States

Question 1

spatial attention can be ____ or ___

Answer 1

DIRECT or COVERT. Covert= secret. you don’t move your head or eyes to the stimuli, but you bring your eyes to peripheral zone. Ex/ seeing something weird but you dont wanna stare but you still watch out of your peripheral vision.

Question 2

involuntary attention is known as ___-up, stimulus driven, ___ attention

Answer 2

involuntary attention is known as BOTTOM-up, stimulus driven, EXOGENOUS attention

Question 3

parallel vs serial search

Answer 3

parallel: when you search the entire picture and look at the object that stands out serial: needing to analyze all components of the image in turn (serially), occurs when something doesn’t POP OUT as much from background. time to find the target increases with the number of distractors.

Question 4

T/F the salience of stimuli that catches our involuntary attention is being computed in PARALLEL rather than serially

Answer 4

true. the time it tkaes for a salient stimulus to capture our attention and popout of the background does not increase significantly s the number of background distractors goes p.

Question 5

the fact that stimuli cayches our involuntary attention is computed parallel rather than serially indicates that:

Answer 5

separate populations of neurons are scrutinizing each region of space for the presence of salient stimuli.

Question 6

overall stimulus salience is probably computed by neurons that receive ___ ___ about multiple stimulus features

Answer 6

CONVERGING INFO about multiple stimulus features (ex/ color, motion, luminance).

Question 7

the ____ of ____ makes a “winning” location temporarily less salient after you paid attention to it, thus ensuring that attention does not get stuck on just a single location

Answer 7

INHIBITION OF RETURN.

Question 8

the bottom up saliency that generates popout effects is the ___ ___. proof?

Answer 8

SUPERIOR COLLICULUS. the superior colliculus receives topographic retinal input and topographic projections from multiple cortical areas. - these converging inputs are consistent with the saliency map the SC is also involved in the targeted eye and head movements. this is also consistent with the saliency map hypothesis the SC also receives somatosenory and auditory inputs, which could mediate involuntary shifts of attention to salient touches or sound.

Question 9

T/F: the superior colliculus is involved in COVERT attention shifting.

Answer 9

TRUE. A small patch of the superior colliculus was stimulated with weak currents (that elicited no overt eye movements) while the monkey tried to perform the movement direction discrimination task . The boost in covert attention is detectable only when the task is neither too easy nor too difficult the SC is involved in attention that involves eye saccades and when the eyes don’t move either. therefore, the SC is involved in both overt and COVERT attention.

Question 10

the idea that both overt and covert spatial attention are controlled by the superior colliculus is conssitent with the observation that both eye movements and covert shifts of visual attention exhibit ____ of ____

Answer 10

INHIBITION OF RETURN. things that were paid attention to both overtly and covertly have temporarily reduced saliency

Question 11

the ___ ___ ___ neurons are reciprocally interconnected with the superior colliculus to help ensure inhibition of the SC. This ensures that there is only one attentional “winner” at time

Answer 11

the lateral tegmental nucleus neurons are reciprocally interconnected with the superior colliculus to help ensure inhibition of the SC. This ensures that there is only one attentional “winner” at time

Question 12

the pulvinar nucleus is located in the ___

Answer 12

thalamus

Question 13

how does the superior colliculus create the perceptual enhancements thtat result from shifts in covert attention?

Answer 13

there are projections from the SC to the pulvinar nucleus of the thalamus. these projectsion are excitatory and topographically organized. increased activity in one part of the superior colliculus by the way of the pulvinar may enhance neural activity in multiply visual cortical areas.

pulvinar lesions are knonwn to cause deficits in visual spatial attention.

Question 14

info from the SC is carried through the ___ __ to the V1 and to higher order visual cortices and the parietal eye field.

the frontal eye field helps direct ___ ___ ___

Answer 14

info from the SC is carried through the PULVINAR NUCLEUS to the V1 and to higher order visual cortices and the parietal eye field.

the frontal eye field helps direct VOLUNTARY SPATIAL ATTENTION

Question 15

THE ___ ___ CONVEYS ATTENTION RELATED SIGNALS FROM THE SC TO THE VISUAL CORTICES

Answer 15

PULVINAR NUCLEUS

Question 16

VOLUNTARY attention is commonly studied in ___ ___ ___ tasks

Answer 16

CUED SPATIAL ATTENTION tasks

Question 17

T/F: Attention boosts responses only to a neuron’s “preferred” stimuli. Why is this phenomena/lack of phenomena beneficial?

Answer 17

true. responses to a stimuli are stronger when attention is directed towards the neuron’s receptive field, where the stimuli are being presented. COVERT VOLUNTARY ATTENTION only strngthens responses to the neuron’s preferred stimuli.

this is important because if attention simply increased neural responses to all stimuli, it would ad more noise to the neural representation of the stimulus and decrease its efficiency.

• covert attention makes it easier for animals to discriminate between similar stimuli.

Image:

Monkeys were trained to direct their attention either to the left of the fixation point or to the right (top right and bottom right of the figure, respectively).

If they correctly identified the stimuli at the attended location, they received a juice reward.

Simultaneously, the experimenters recorded the orientation preferences of V4 neurons to stimuli in their receptive fields.

The major finding was that attending to a stimulus location increases the responses of neurons with receptive fields in the attended area (the graph shows the results for one such neuron), but that this attention-driven boost occurs only for responses to preferred stimuli.

Question 18

electrical stimulation of the _____ significantly enhances visual responses of ___ neurons, IF the receptive files of the neurons coincide with the eye movement fields of the stimulated ___ neurons.

Answer 18

electrical stimulation of the FEF significantly enhances visual responses of V4 neurons, IF the receptive files of the neurons coincide with the eye movement fields of the stimulated FEF neurons.

this implied that low intensity FEF stimulation triggers a shift in COVERT spatial attention rather than a general arousal of the animal.

Question 19

Frontal eye field activity correlates with covert voluntary attention. Explain the experiment done

Answer 19

1) monkeys were trained to find a target stimulus (line of a particular color and oreientation) using SERIAL SEARCH STRATEGY
2) they kept their eyes focused on a central point, indicating that they searched for the target COVERTLY
3) they began their covert serial search on the right side of the stimulus array and then searched in a clock wise dirction
4) neurons whose receptive field contained the target stimulus showed an increase in firing rate BEFORE the monkey responded overtly. seen that FEF neurons with receptive fields located immediately counterclockwise to the target increased their firing rate BEFORE the monkeys response and then reduced it again by the time the eye movement response began. therefore, the FEF NEURONS INCREASE THEIR FIRING RATE whenever the attentional spotlight enters their receptive field

Question 20

what is hemispatial neglect and how is it caused?

Answer 20

hemispatial neglect is an ATTENTIONAL disorder in which there is a decreased ability to shift attention from the right side to the left. the entire world on the left side is neglected.

this is due to large portions of the parietal and temporal lobes being daamaged. pts with neglect have damage in the:

1) inferior parietal cortex
2) superior temporal cortex
3) temporo-parietal junction.

right inferior parietal and superior temporal lesions REDUCE ACTIVATION of more dorsal-frontal and parietal areas in ATTENTION-DEMANDING TASKS.

Question 22

____ NEURONS are causally involved in guiding covert voluntary spatial attention.

Answer 22

FEF. this is solified with the fact that gaba agonist (mucimol) impairs ovluntary shifts of covert spatial attention

Question 23

weak activity in the SC and FEF generate _____ shifts of attention, whereas higher levels of activity in the same brain regions cause ____ orienting movements

Answer 23

weak activity in the SC and FEF generate COVERT shifts of attention, whereas higher levels of activity in the same brain regions cause OVERT orienting movements

Question 24

voluntary eye movements is linked more closely to the ___, whereas involuntary attention is linked to the ___ ____, which is more closely linked to reflexive, involuntary orienting movements.

Answer 24

voluntary eye movements is linked more closely to the FEF, whereas involuntary attention is linked to the SUPERIOR COLLICULUS, which is more closely linked to reflexive, involuntary orienting movements.

Question 25

Note: parietal eye field integrate info from the saliency map in the superior colliculus with top down info from the frontal eye fields. the notion that the parietal cortex (parietal eye field) is involved in the control of spatial attention is further supported by the obsevation that lesions of the right parietal cortex often causehemispatial neglect.

Question 26

difference between attention and arousal

Answer 26

arousal is not selective, attention is selective. when arousal levels rise, all sorts of stimuli become more likely to elicit a response.

Question 27

as individuals go from being alert to being drowsy, eeg ____ in amplitude and starts to exhibit ____, rhytmic oscillations.

Answer 27

as individuals go from being alert to being drowsy, eeg INCREASES in amplitude and starts to exhibit SLOW, rhytmic oscillations.

Question 28

Wakefulness and behavioral arousal are associated with EEG _____(smaller, more irregular EEG traces).

Answer 28

EEG DESYNCHRONIZATION

Question 29

EEG desynchronization

Answer 29

refers to the DECREASE IN EEG AMPLITUDE that acompanies behavioral arousal.

Question 30

the link between neuronal synchrony and EEG amplitude arises because:

Answer 30

the dendrites of neocortical pyramidal neurons tend to be arranged in parallel to one another and perpendicualr to the neocortical surface. As a result of RADIAL ALIGNMENT, synchronous activation causes the dendritic potentials generated by the individual pyramid neurons to SUM rathe than cancel. the larger the sum, the larger the deflections in the EEG.

Question 31

Electrical stimulation in the ___ ____ can trigger arousal. This effect probably results from the activation of ____ axons from locus coeruleus and cholinergic axons from _____ neurons.

Answer 31

Electrical stimulation in the reticular formation can trigger arousal. This effect probably results from the activation of noradrenergic axons from locus coeruleus and cholinergic axons from peribrachial neurons.

Question 32

the locus coeruleus is contains primarily ____ cell bodies

Answer 32

noradrenergic

Question 33

what are the two principal ascneding arousal systems

Answer 33

1) cholinergic neurons in peribrachial area
2) locus coerleus NE neurons.

Question 34

• Most neurons become more responsive to stimuli and reduce their background firing rate in response to ____ stimulation. The prefrontal cortex is unusual in that its neurons are inhibited by high levels of norepinephrine.

Answer 34

• Most neurons become more responsive to stimuli and reduce their background firing rate in response to noradrenergic stimulation. The prefrontal cortex is unusual in that its neurons are inhibited by high levels of norepinephrine.

Question 35

what are the features of the locus coeruleus that allow it to influence a large number of widely dispersed neurons and brain structures?

Answer 35

1) because noradrenergic synapses lack a glial barrier, released NE can diffuse out of the synapse to more distant receptors, influencing a large number of post synaptic neurons
2) neurons of LC are ELECTRICALLY COUPLED, which means that depolarization in one neuron spreads through gap junctions to its neighbors.

Question 36

outline the synthesis of NE and DA from tyrosine.

Answer 36

Question 37

what type of stimuli controls the locus coeruleus activities?

Answer 37

there is a coreelation with behavioral arousal and the locus coeruleus. it is activated when animals have to learn to associate rewards and punishments. the LC firing rates increase in to whichever stimulus is linked to the reward. this is consistent with the idea that the LC activation occurs after the presentation of a SALIENT, AROUSING, STIMULI.

Question 38

WHAT HORMONG ACTIVATES THE LC

Answer 38

Epinephrine. this hormone does not cross the BBB, but its levels in the blood are sensed by neurons in the bagus nerve. these neruons project to the nucleus of the solitary tract, which in turn project to nucleus coruleus.

Question 39

how is the LC part of a positive feedback loop?

Answer 39

epinephrine excites the LC. LC activation stimulates the CENTRAL AMYGDALA, which activates a variety of other neurons that ultimately cause the release of cortisol and epinephrine from the adrenal gland, which stimulates more LC activation

Question 40

is the LC is part of an epinephrine feedback loop, how can you ever calm down?

Answer 40

some neurons of the LC project onto themselves and express ALPHA 2 ADRENERGIC RECEPTORS that inhibit post synaptic cells. Therefore, the LC activity is kept in check by a short feedback loop. when the LC is excited, these inhibitory neurons are stimulated along with a positive feedback loop.

Question 41

Activation of the LC leads to EEG ____ and can wake a sleeping animal

Answer 41

EEG Desynchronization

Question 42

activation of the LC increases sensory responses of ____ neurons

Answer 42

incereases sensory responses of thalamic neurons (which in turn alter the rate of responses in the sensory cortices of the neocortex)

Question 43

how does the LC interact with the sensory neocortex

Answer 43

when LC is stimulated, it suppresses SPONTANEOUS BACKGROUND ACTIVITY and responses to weak thalamic inputs. in effect,the LC activation enhances sensory responses that are ALREADY STRONG and suppresses everything else. it increases the SIGNAL TO NOISE RATIO and enhances the MAIN SIGNal

Question 44

TF: the LC projects onto the motor cortex in addition to primary sensory cortices

Answer 44

TRUE. they even project MORE HEAVILY to motor and prefrontal cortices than to primary sensory cortices.

Question 45

Explain the variability as to how the prefrontal cortical neurons respond to NE

Answer 45

these neurons become more active as NE levels rise, then they SHUT DOWN as NE levels increase past a certain point.

Question 46

neurons expressing ___ or ___ adrenergic receptors tend to become more active in response to NE, whereas neurons that express ___ adrenergic receptors (including the LC neurons themselves) tend to be inhibited by NE. What is an exception to this?

Answer 46

neurons expressing A1 or B adrenergic receptors tend to become more active in response to NE, whereas neurons that express A2 adrenergic receptors (including the LC neurons themselves) tend to be inhibited by NE

Exception in the prefrontal cortex: they are excited by A2 receptor activation and inhibited by A1 activation. because A2 receptors bind NE at lower concentrations than A1 receptors do, Prefrontal neurons are excited at low levels of NE and inhibited as more NE is released.

Question 48

what is the adaptive advantage for the prefrontal cortex shutting down at the levels of NE when LC gets activated

Answer 48

LC gets activated in times or arousal/reward/motivation. Also in times of stress. boosting PFC function may get in the way of rapid reactions because the PFC fucntions are relatively slow to execute and tend to inhib rapid response. therefore, taking the PFC offline may be adaptive during extremely stressful situations when immediate actions are required.

Question 49

Sleep is divisible into ___ ____ and ___ sleep.

Answer 49

slow wave and REM sleep

Question 50

During REM sleep, the EEG is as _____ as it is during the waking state, but muscle tone is _____

Answer 50

During REM sleep, the EEG is as desynchronized as it is during the waking state, but muscle tone is minimal.

Question 51

The rhythmic activation of cortical neurons during slow-wave sleep results from intrinsic neuronal rhythms as well as looping interactions between the ____, the ___ ____ , and the ___ ___ ___ .

Answer 51

The rhythmic activation of cortical neurons during slow-wave sleep results from intrinsic neuronal rhythms as well as looping interactions between the neocortex, the dorsal thalamus, and the thalamic reticular nucleus.

Question 52

Waking from sleep involves the activation of ____ ___ cholinergic neurons, which receive input from glutamatergic ____ neurons, ____ ____ and hypocretin neurons in the ___. Loss of the hypocretin neurons causes ____.

Answer 52

Waking from sleep involves the activation of basal forebrain cholinergic neurons, which receive input from glutamatergic peribrachial neurons, locus coeruleus, and hypocretin neurons in the hypothalamus. Loss of the hypocretin neurons causes narcolepsy.

Question 53

A small group of neurons in the____ ____ area is more active during sleep than during waking. These neurons inhibit _____-promoting neurons and are, in turn, inhibited by them.

Answer 53

A small group of neurons in the ventrolateral preoptic area is more active during sleep than during waking. These neurons inhibit wakefulness promoting neurons and are, in turn, inhibited by them.

Question 54

allostatic control

Answer 54

a PHASIC response to SITUATIONAL stresses. through physiological or behavioral change. This can be carried out by means of alteration in HPA axis hormones, the autonomic nervous system, cytokines, or a number of other systems, and is generally adaptive in the short term

Question 55

Compare alpha, beta, theta and delta waves

Answer 55

alpha waves: SMOOTh electrical activity recorded from generally associated with a state of RELAXATION
beta activity: irregular electrical acitvity of 13-30 Hx recorded from generally associated with a state of AROUSAL

theta activity. intermittent, associated with stages of slow wave sleep and REM
Delta activity: regular, SYNCHRONOUS, electrical activity of less than 4 Hz. Ocurs during the DEEPEST stages of sleep.

Question 56

On an EEG, _____ frequencies dominate during slow-wave (SW) sleep but vanish during rapid eye movement (REM) sleep

Answer 56

Low frequencies dominate during slow-wave (SW) sleep but vanish during rapid eye movement (REM) sleep

Question 57

a major role in generating the slow rhythms of the cortical EEG is played by neurons in the ___ ___

Answer 57

dorsal thalamus

Question 58

what mechanism generates the dorsal thalamic rhythymm responsible for creating neocortical rhythym?

Answer 58

dorsal thalamus receives major GABAergic input from the thalamic reticular nucleus. the TRN fires bursts of APs just before each burst of activity in thalamocortical neurons.

Question 59

thalamic reticular neurons are ____ and project to the thalamocortical neurons

Answer 59

INHIBITORY.

You can see that the thalamic reticular neuron fires in rhythmic bursts, followed 100–300 ms later by bursts of activity in the thalamocortical neuron.

This pattern of activity is consistent with the hypothesis that bursts of thalamic reticular activity inhibit thalamocortical neurons;

when this inhibition ends, the thalamocortical neurons rebound with a burst of action potentials of their own (this phenomenon is called post-inhibitory rebound

Question 60

Explain the postinhibitory rebound phenomenon that helps keep the EEG oscillation loop steady

Answer 60

bursts of thalamic reticular activity inhibit thalamocortical neurons;

when this inhibition ends, the thalamocortical neurons rebound with a burst of action potentials of their own (this phenomenon is called post-inhibitory rebound

the thalamocoritcal rebound spike triggers a burst of activity in the thalamic reticular neurons, then the cycle repeats.

thalamocortical and thalamic reticular neurons form an oscillatory feedback loop that can explain the rhythmic firing in both sets of neurons during SLOW WAVE SLEEP.

Question 61

explain the intrinsic rhythym of a thalamocortical rhythmic neuron

Answer 61

thalamocortical neurons can generate APs in which the depolarizing current is done by CALCIUM and not by Na+. these calcium spikes occur at LOWER THRESHOLDS and result in thalamocortical neurons firing a burst of ACTION POTENTIALS before reverting to the hyperpolarized state it displayed before the calcium spike.

the falling membrane potential after a calcium spike opens a HYPERPOLARIZATION-ACTIVATED CHANNEL, which generates H CURRENTS that slowly DEPOLARIZES the neuron until it fires another Ca2+ spike again.

Therefore, the thalamocortical neuron is influenced by its own independent rhmicity, plus its connections with the thalamic reticular neurons

Question 63

two reasons as to why rhythmically active neurons become synchronized to one another to cause large EEG oscillations

Answer 63

1) cortical neurons with similar rhythms synchronize each other by means of excitatory intracortical connections
2) neuronal synchronization may also be accomplished by GAP JUNCTIONS between reticular thalamic neurons. synchrony among the thalamic reticular neurons should synchronize the corticothalamic and neocortical neurons.

Question 64

why is it that people in deep sleep are difficult to wake?

Answer 64

its because ascending inputs arriving at the dorsal thalamus have trouble getting through to the neocortex. Although sensory detection and processing can occur during sleep, thalamocortical neurons respond pooly to ascending inputs during slow wave sleep. therefore, the neocortex in feep sleep is largely cut off from the world.

Question 65

although the LC neurons can wake a sleeping animal, they do so in COLLABORATION with neurons in the ___ ____ and upper p___ that use acetylcholine as their transmitter.

Answer 65

basal forebrain and upper pons that use acetylcholine as their transmitter.

Question 66

cholinergic peribrachial neurons project to both the ___ ___ and the____

Answer 66

basal forebrain and the thalamus

Question 67

within the thalamus, peribrachial neurons innervate both the ___ ___ and the ___ ___ ___

Answer 67

innervate both the dosal thalamus and the thalamic reticular nucleus.

Question 68

what does peribrachial-acetylocholine release do to the dorsal thalamus (thalamocortical neurons)?

Answer 68

causes slow depolarization of hte post synaptic neurons by closing K+ channels until they are so depolarized that they stop firing the calcium spikes. Recall that the calcium spikes are initiated when the cell is hyperpolarized and channels open up to create a Ca2+ H current.

Question 69

what does peribrachial-acetylcholine release to in the thalamic reticular nucleus?

Answer 69

causes a brief depolarization, followed by a LONG LASTING HYPERPOLARIZATION that reduces overall activity of the reticular neurons, which in turn decreases the rhymic inhibition of the dorsal thalamus.

Question 70

what is the ultimate outcome of peribrachial neurons exerting effects on the dorsal (thalamocortical) and thalamic reticular neurons?

Answer 70

dorsal thalamic neurons stop bursting rhythmically and become more capable of responding to ascending inputs with individual action potentials. this explains why stimulation of the cholinergic peribrachial neurons DESYNCHRONIZED the EEF and makes the neocortex more responsive to external stimuli.

Question 71

cholinrgic neurons in the basal forebrain (partially involved in waking us up) project to the ___ as well as to the ___ and the ____

Answer 71

project to the neocortex as well as to the hippocampus and amygdala.

Question 72

T/F: projections from the basal forebrain are non-topographic, meaning that neighboring neurons project to different targets

Answer 72

true. there, even HIGHLY localized stimulation of the basal forebrain tends to cause widespread acetylcholine release.

Question 73

where is the basal forebrain located

Answer 73

in the neocortex

Question 74

what is the maineffect of cholinergic neurons in the basal forebrain

Answer 74

they project into the neocortex as well as to the HC and the amygdala.

slow depolarization ,whcih reduces the tendency of the neurons to fire rhytmic bursts of action potentials.

• also hyperpolarizes astrocytes
• both results in the REDUCTION of the slow rhythyms in the EEG.

Question 75

what activates the basal forebrain cholinergic neurons to begin with?

Answer 75

1) excitatory input comes from the peribrachial neurons that use glutamate, rather than ach, as their main transmitter.

therefore, the peribrachial region can desynchronize the EEG through two different pathways: one pathway reduces the tendency of thalamic neurons to oscillate, the other pathway activates the basal forbrain’s cholinergic neurons, which then reduce the tendency of neocortical neurons to fire rhythmically.

2) excitatory input comes from the locus coeruleus.

Question 76

in addition to cholinergic (basal forbrain and brachial) and noradrenergic (LC0 the brain contains a third and fourth set of neurons that become active when the animal is awake. what are they?

Answer 76

1) the tuberomammilary nucleus of the posterior hypothalamus that utilizes HISTAMINE
2) lateral hypothalamus, that uses HYPOCRETIN NEUROPEPTIDE.

Question 77

what condition is associated with a 90% loss of hypocretin neurons in the lateral hypothalamus?

Answer 77

narcolepsy

Question 78

How do the hypocretin neurons desynchronize the EEG

Answer 78

they activate other wakeful-ness promoting regions (LC, basal forbrain, tuberomammilary region, peribrachial). they all have hypocretin receptors and so the hypocretin neurons in the lateral hypothalamus desynchronize the EEG and rouse sleeping animals indirectly by prompting other wakefullness promoting brain regions to spring into action.

Question 79

if the hypocrein neurons in the lateral hypothalamus activate all the other wakefulness promoting regions, what activates the hypocretin neurons?

Answer 79

no one is really sure but they probably receive some input from the SCN which helps regulate sleepwake cycles

Question 80

when looking at cfos expression, a gene which increases shortly after neurons have been highly active, between rats that had been sleeping and rats that had been awake, what did researchers find?

Answer 80

only the SCN and the ventrolateral preoptic area (vlPOA) exhibited more cfos positive cells in sleeping animals.

researhc then revealed that the vlPOA is active whenever an animal is asleep, whenever it occurs, even during the day.

Question 81

what happens if you lesion the vlPOA

Answer 81

vlPOA is active when you are asleep and produces cfos. if you lesion it, you probably wont be able to sleep because it needs to be active for you to go to bed.

Question 82

vlPOA neurons are ___ and project to the LC as well as to the tuberomammillary (histamine) and hypocretin neurons

Answer 82

GABAergic

Question 83

explain the sleep toggle switch

Answer 83

the vlPOA and LC are reciprocally innervated by inhibitory NE projections from the LC to the vlPOA. This means that the LC and vlPOA inhibit each other, creating clean and stable tranisionts between waking state and sleep.

image: you can see that the ventrolateral pre- optic area (vlPOA) is active during sleep and inhibits the areas that promote wakefulness, namely, the cholinergic basal forebrain neurons (Bas), and the locus coeruleus (LC), tuberomammillary (TuMa), and hypocretin neurons.

Conversely, vlPOA is inhibited during the waking state.

Question 84

in addition to SCN circadian activity what other sleep inducing factors may accumulate while you’re awake and dissipate when you’re asleep? Mechanism?

Answer 84

adenosine; biproduct of ATP metabolism. Adenosine inhibits basal forebrain cholinergic neurons and increases sleep duration. the fact that caffeine is a potent adenosine receptor blocker largely explains why caffeine is so effective at keeping you awake.

by inhibiting the basal forebrain cholinergic receptors that typically inhibit vlPOA, the sleep promoting region of vlPOA is activated, resulting in sleep.

Question 85

T/F: just like you were awakw, the LC and tuberomammilary neurons and hypocretin neurons and basal forbrain cholinergic neurons are acitvated during REm

Answer 85

FALSE. only the basal forbrain cholinergic neurons are active during REM sleep. the other wakefulness promoting regions stay silent.

Question 86

When is serotonin the most readily seen during sleep?

Answer 86

RIght after REM sleep

Question 87

what happens to skeletal muscle during muscle atonia? Mechanism?

Answer 87

muscle atonia results in temporary paralysis while sleeping. the body’s main straited muscles lose their muscle tone during REM sleep. This muscle atonia occurs because the skeletal moto neurons are HYPERPOLARIZED.

this inhibition of the mottor neuonrs occurs by SUBCOERULEUS REGION, which lies ventral to the locus C. its glutaminergic neurons project to INHIBITORY neurons with direct projectsion to skeletal moto nruons in the brain stem and spinal cord.

Question 88

this inhibition of the mottor neuonrs during SLEEP ATONIA occurs by ____ ____ , which lies ventral to the locus C. its______ neurons project to INHIBITORY neurons with direct projectsion to skeletal moto nruons in the brain stem and spinal cord.

Answer 88

this inhibition of the mottor neuonrs during SLEEP ATONIA occurs by SUB CORULEUS which lies ventral to the locus C. its GLUTAMINERGIC neurons project to INHIBITORY neurons with direct projectsion to skeletal motor neurons in the brain stem and spinal cord.

Question 89

outline the REM toggle switch

Answer 89

The muscle atonia is due to motor neuron hyperpolarization, as shown here for a jaw motor neuron.

Panel (B) shows the neural network responsible for switching between slow-wave and REM sleep.

The ventrolateral periaqueductal gray (vl-PAG) and the subcoeruleus region are thought to inhibit one another, forming a toggle switch.

Question 90

what triggers REM sleep?

Answer 90

2 hypothesis: 1)rem begins when glutaminergic neurons in the peribrachial region becomes active and excites the basal forebrain cholinergic neurons

2) ventrolateral PAG falls silent during REM sleep, disinhibiting their target neurons in the peribrachial and subcoeruleus regions. an interesting aspect of this second hypothesis is that the SUB C. region contains GABAergic neurons that project back to the vlPAG. thus, the subC neurons and the vlPAG neurons may mutually INHIBIT one another, forming a toggle swtich that determines whetehr the animal will bein REM or SLOW WAVE

Question 91

REM sleep is beneficial to _____ memory

Slow wave sleep is beneficial to ____ memory.

Answer 91

REM sleep is beneficial to nondeclarative memory ((mirror drawing).

Slow wave sleep is beneficial to declarative memory. (word list)

Question 92

why is the brain not totally silent during sleeP/

Answer 92

if the brain was totally asleep it would not be capable of triggering thermoregulatory behaviors, and would increase the risk of hypothermia.

Question 93

how does sleep allow for the process of toxin clearining?

Answer 93

the interstitial space between brain cells increases while a person is asleep because astrocytes shrink at that time. the increase in interstical space, in turn, allows the CSF to flow much faster through the brain, increasing the rate at which potential toxins and waste products are removed.