Flashcards in Limbic System Part 1 Deck (66):
What cortical and subcortical regions make up the limbic sytem?
cortical: prefrontal, cingulate, insula, parahippocampual gyrus
subcortical: amygdala, hippocampus, ventral striatum/nucleus accumbens
What does the limbic system do?
memory, motivation, emotions
What part of the brain is responsible for planning?
prefrontal cortex and cingulate gyrus
What part of the brain is responsible for cognition?
What part of the brain is responsible for stress?
HPA axis, hippocampus, amygdala
What part of the brain is responsible for fear?
What part of the brain is responsible for memory?
hippocampus and entorhinal cortex
What does the reticular formation do?
projects to cortex, thalamus, brain stem and spinal cord with long neurons for wakefulness, alerting. ARAS (ascending reticular activating system)
What does the neurotransmitter norepinephrine modulate?
attentional selectivity during stress
What does the neurotransmitter dopamine modulate?
promote motivationally based behavior
Where is norepinephrine released from?
locus ceruleus (in the pons)
What does the neurotransmitter serotonin modulate?
mood, sleep and wakefulness cycles (5-HT)
What does the neurotransmitter acetyl choline modulate?
facilitates hippocampal and cortical memory and cognition
What is the function of the lateral prefrontal cortex?
working memory, executive control (motivation, goals that regulate behavior)
What is the function of the orbitofrontal cortex?
reward, motivation, emotional decisions
What is the function of the ventromedial cortex (frontal)?
includes medial PFC and anterior cingulate. emotional responses, declarative memory. connects with amygdala, hippocampus, n accumbens
What is the overall function of the prefrontal cortex?
planning, top-down control of attention, behavior, emotion. connections to reticular nuclei regulate PFC inputs. intelligent thought
Where is the hippocampus?
medial temporal lobe, up against the third ventricle in the three-layered archicortex
What is the afferent pathway to the hippocampus?
cortical regions for sensory, assoication etc -->parahippocampal gyrus -->entorhinal cortex --> hippocampus
What is the efferent pathway from the hippocampus?
hippocampus --> entorhinal cortex-->parahippocampal gyrus --> cortical regions, processed as memory
What are the two forms of long term memory?
implicit (procedural) and explicit (declarative)
What part of the brain modulates declarative (explicit) memory?
hippocampus and medial temporal lobe (this is events/episodic and facts/semantic memory)
What part of the brain modulates the emotional type of procedural (implicit) memory?
What part of the brain modulates working memory?
What are two types of declarative (explicit) memory?
episodic and semantic
What area of the brain encodes episodic memory? What type of memory is episodic memory?
The hippocampus encodes it, then sends it to areas of the cortex. episodic memory is auto-noetic consciousness (with self in it) and declarative (explicit)
In what two areas of the brain are semantic memory consolidated?
anterior temporal lobe and lateral prefrontal cortex
What kind of memory is semantic memory?
noetic declarative (explicit). consciousness of knowledge without a sense of self/ accompanying experience
What are the two distinctive regions of declarative memory consolidation and what information do they extract from memory?
anterior system: relates representations of specific entities
posterior system: matches cues about context to interaction of entities and environment (spatial landmarks, cues, location...)
What area of the brain coordinates precise recall of various aspects of episodic memory?
retrosplenial area of the cingulate gyrus
What is an EEG and what does it measure?
electroencephalogram, measures summation of synchronous postsynaptic potentials (EPSP and IPSPs)
What happens to EEG waves during sleep progression from stages 1-4?
the EEG waves increase in amplitude and decrease in frequency
What does the EEG wave look like during REM sleep?
similar to waking- low amplitude, high frequency
The first half of nocturnal sleep is dominated by_________, whereas the second half of nocturnal sleep is dominated by ______.
slow-wave sleep, REM sleep
What happens to sleeping patterns as we age?
slow-wave sleep amount declines
wakefulness/arousal is initiated and maintained by:
ascending pathways from the reticular formation to the thalamus and cortex. regulated by SCN-->VLPO-->hypothalamus and brainstem (via GABA mediated inhibition)
cholinergic pathways that activate the thalamus, facilitating thalamo-cortical transmission are generally most active during _____ sleep
waking and REM sleep
monoaminergic pathways that activate the cortex, facilitating the processing of thalamic input is generally more active during______ sleep
What pathway is degenerated in narcolepsy?
orexin/hypocretin pathway from the lateral hypothalamus (normally activating the cortex)
What nucleus regulates sleep and how does it do it?
ventrolateral preoptic nucleus (VLPO) regulates sleep by inhibiting hypothalamic and brain stem nuclei that normally participate in wakefulness. VLPO inhibits these via GABA and discharges selectively throughout sleep
How does the SCN regulate wakefulness during light phases?
SCN-->SPZ-->DMH of hypothalamus, inhibit VLPO with GABA and stimulates orexin neurons via glutamate
What happens to the sleep cycle during sickness?
cytokines disrupt the circadian cycle to permit sleep during the day (TNF, IL...)
Activation of the cortex during wakefulness is mediated by release of ______ and ______ neurotransmitters from ______.
norepinephrine and serotonin from the reticular formation (that was activated by the hypothalamus)
activation of thalamic processing of sensory informaiton during wakefulness if mediated by release of ______neurotransmitter from ______.
acetylcholine released from the reticular formation (that was activated by the hypothalamus)
What happens to the cholinergic and adrenergic corticothalamic pathways during slow-wave sleep?
are inhibited by GABA
Why can't we hear anything during slow-wave sleep?
transient downregulation of cortical areas inhibits the auditory cortex ( a sleep protection mechanism)
During slow-wave sleep the body is ______ but the mind is ______ (active/inactive?)
decrease in muscle tone, HR, BP... during SWS but still can toss/turn. thus active body, inactive mind during SWS.
during what stage of sleep does sleep walking occur?
What happens to cholinergic pathways and thalamocortical transmissions during REM sleep?
increase in cholinergic stimulation (greater than waking!) and thalamo-cortical transmission similar to when waking
During REM sleep the body is ______ but the mind is ______ (active/inactive)?
body is inactive (paralyzed actually) and the mind is active
What are the two types of REM sleep and what are they characterized by?
Phasic REM: extensive REM, high brain activity (dreaming?) and external sounds suppressed.
Tonic REM: no REM, increased reactivity to outside stimuli (espsecially auditory)
When are we most susceptible to auditory stimuli (alarm clock, eg) during sleep?
Tonic REM stages
What are four physiological functions that correlate with REM stage?
eye movements, heart rate (increased), respiratory rate (increased), penile erection
What activity might regulate how long an REM cycle is?
cholinergic/serotonergic feedback cycles
What happens to acetylcholine levels during wakefulness and how does that affect memory?
Ach increases during wakefulness. this increases sensory input and encoding of memories in the hippocampus
What happens to Ach levels during SWS and how does this affect memory?
Ach decreases during SWS, this increases the reactivation of memories in the hippocampus, transfering memories to the neocortex
cortical slow waves are associated with _______activity and therefore memory ______.
cortical slow waves are associated with increased hippocampus acitivity and therefore memory reactivation (for consolidation in the cortex)
Memories are stored in the _____ during SWS
Reactivation of memories during waking results in:
disruption by interference of other sensory inputs (easily labile)
Reactivation of memories during SWS results in:
stabilization and consolidation of the memory
Reactivation of memories during REM results in:
insight, discovery of correlations across episodes
How does the septum affect memory consolidation?
separates periods of encoding of current sensory stimuli and retrieval to avoid interference
How does the nucleus basalis affect memory?
projects to the neocortex to facilitate memory consolidation
What part of the brain and memory storage is damaged in Alzheimers?
imparied cortical cholinergic neurotransmission, degeneration of the cortex, degeneration of the nucleus basalis. defective processing of beta-amyloid precursor--> amyloid plaques. --> inability to consolidate long and short term memories
What are the symptoms of Korsakoffs Syndrome? What is it caused by?
loss of memory consolidation, with confabulation.
due to degeneration of thalamic nuclei and mamillary bodies from alcoholism.