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Organ Systems III > Exam 4 > Flashcards

Exam 4 Flashcards

0
Q

Describe the neuromodulatory system that utilizes norepinephrine.

A

Projections from locus ceruleus in pons go to cortex to provide attentional selectivity under stress.

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1
Q

What are the cortical and subcortical regions of the brain that make up the limbic system?

A

Cortical regions include prefrontal, cingulate, insula, parahippocampal gyrus
Subcortical regions include hippocampus, amygdala, ventral striatum, nucleus acumbens

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2
Q

Describe the neuromodulatory pathway that utilizes dopamine.

A

Projections from ventral tegmentum of midbrain to PFC and BG to promote motivational based behavior

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3
Q

Describe the neuromodulatory pathway that utilizes serotonin.

A

Raphe nucleus of medulla projects to cortical areas to support mood and sleep/wake cycles

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4
Q

Describe the neuromodulatory pathway that utilizes acetylcholine.

A

Septum, nucleus basalis, and diagonal band of broca project to thalamus and cortex to consolidate memory and support cognition

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5
Q

Where is the hippocampus located?

A

Surface of medial temporal lobe, bulging into lateral ventricle

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6
Q

What are the afferents and efferents that connect to the hippocampus?

A

AFFERENTS: sensory, association, cingulate, and PFC –> parahippocampal gyrus –> entorhinal cortex –> hippocampus
EFFERENTS: opposite pathway of afferents through entorhinal cortex

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7
Q

What is the main function of the hippocampus?

A

Consolidation of memory in the cortex (PFC) for declarative memory function

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8
Q

What is declarative memory? Distinguish between episodic and semantic memory.

A

Declaritive memory can be episodic or semantic
Episodic memory is from experiences and spatial/temporal context of an event
Semantic memory is facts and data

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9
Q

Describe the role of the hippocampus and vmPFC in forming and consolidating declarative memory. Where is declarative memory stored?

A

Anterior Temporal (semantic) and Posterior Medial (episodic) systems extract essential information during experience of event and consolidates
Declarative memory is stored in the regions of the cortex to which the hippocampus projects
Episodic is stored in mPFC, parahippocampal gyrus, entrohinal, perirhinal, lateral temporal, and parietal association cortices
Semantic is consolidated mainly in lateral temporal and lateral PFC

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10
Q

Describe the stages of sleep and their EEG correlates. Compare SWS and REM stages of sleep.

A

Non-REM (SWS) sleep (stages I-IV) - EEG waves increase amplitude and decrease frequency
REM sleep - EEG waves are similar to waking (low amplitude, high frequency)

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11
Q

What are the pathways that maintain wakefulness, and how do you fall asleep? How is sleep regulated by a circadian cycle?

A

Wakefulness is initiated and maintained by ascending reticular pathways to thalamus and cortex (cholinergic pontine pathways from from PPT and LDT)
Sleep is regulated by VLPO of hypothalamus
SCN of hypothalamus regulates circadian rhythm

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12
Q

Describe how memory is consolidated in sleep: When does reactivation of memory occur during sleep? When are memories consolidated? What role does the septum and diagonal band of Broca have in this?

A

Early SWS consolidates declarative and procedural memory
REM reshapes and consolidates memories
Reactivation of memories occurs during SWS and consolidated for permanent storage through ACh pathways from hippocampus

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13
Q

What sleep-wake conditions optimize memory consolidation?

A

SWS provides on-off periods for consolidation of memories from hippocampus to cortical sites without outside sensory input disruption

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14
Q

How is memory consolidation affected in Alzheimer’s disease? Bilateral hippocampectomy?

A

In Alzheimer’s, amyloid plaques and degeneration of cholinergic tracts of cortex leads to inability to consolidate short term to long term memories - similar symptoms result from Korsakoff’s syndrome (alcoholism)
With a bilateral hippocampectomy, memory consolidation is lost causing only long term memory to be present

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15
Q

How are emotional experiences manifested? What role does the amygdala play in expressing these manifestations?

A

Emotional experiences are either manifested by:
ANS (changes in BP/digestion/bloodflow)
Behaviors (facial expressions)
Subjective feelings (love/fear)
Central nucleus of amygdala is involved in cognitive-emotion interactions and consolidating them into memory

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16
Q

How do the efferent pathways from the amygdala generate affective/emotional attention?

A

Ascending projections from amygdala via basal forebrain influence information processing and memory consolidation through cortex
Descending projections via hypothalamus/brainstem lead to ANS modifications and mobilization of bodily resources

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17
Q

What types of facial expressions do the amygdala respond to and why?

A

Amygdala primarily responds to faces that are ambiguous (fear/surprise) in order to get more information for cortical arousal via ACh efferent pathways that tune up sensory system

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18
Q

What is emotional memory? What structures are involved in emotional memory?

A

Amygdala consolidates emotional memory directly to mPFC and indirectly to other areas of cortex (cingulate, insula, hippocampus)

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19
Q

Describe conditioned fear and extinction and what brain areas generate them.

A

Amygdala mediates acquisition of conditioned fear as sensory cues are associated with aversive events
Extinction of conditioned fear is due to vmPFC inhibition of amygdala - emotion is inhibited, but not forgotten
*Failure of this inhibition leads to maladaptive behaviors and emotional preservation

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20
Q

How is the amygdala regulated in its expression of emotional responses?

A

Hippocampus adds context to amygdala

mPFC regulates amygdala response

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21
Q

What does it mean that the amygdala retrieves emotional memories unconsciously?

A

Emotional memories can then be recalled unconsciously/subliminally via pulvinar nucleus of hypothalamus, insula, and association cortices

22
Q

Compare memories of emotions vs emotional memories.

A

Hippocampus projections are responsible for explicit, declarative memories (memories about emotion) while amygdala forms implicit, emotional memory

23
Q

How do high levels of NE and DA neuromodulation affect the relationship of prefrontal cortex and amygdala?

A

High NE and DA with stress inhibit PFC function of working memory and attention while strengthening fear conditioning of amygdala (anxiety)

24
Q

What is meant by top-down and bottom-up control of the amygdala?

A

‘Top-down’ control by PFC answers what is most relevant to the task at hand
‘Bottom-up’ control by sensory cortices captures salience of stimulus to get attention

25
Q

What effects do lesions of the vmPFC/OFC and of the amygdala have on behavior?

A

Lesion of vmPFC/OFC results in inability to plan ahead and recognize consequences of actions and inhibit emotional tendencies of amygdala
Lesion of amygdala results in inability to link experiences to stimuli and recognize strong emotions

26
Q

Describe the location and some of the functions of the insula.

A

Insula is located between frontal and temporal lobes
Involved in emotional awareness of smell, taste, and visceral feelings as well as mapping internal states of the body
Anterior perceives pain/temp and posterior perceives somatosensation

27
Q

How does the insula relate to the amygdala?

A

It projects to the amygdala

28
Q

What role does the insula play in empathy? In anxiety?

A

Observation of emotionally laden actions generate viscero-motor aspects of emotion giving first person experience
Predictive representation, as seen in mirror neurons
Hyperactivation of insula leads to increased anticipatory input to amygdala which causes anxiety

29
Q

What is working memory?

A

Executive function of brain that maintains and updates task-relevant representations through NE and DA input - ‘mental sketch pad’

30
Q

Describe the dlPFC and its role in working memory.

A

dlPFC is sensitive to DA and NE, requiring proper levels for optimal mental alertness

31
Q

Compare lateral and medial PFC connections and functions.

A

Lateral PFC connects with sensory/motor association cortices for intentional regulation of emotional behavior and experience for executive actions such as selective attention/planning
Medial PFC connects with amygdala, insula, and hippocampus associated with social, emotional, and appetitive stimuli involved with reward aspects of tasks

32
Q

What is the significance of the prefrontal cortex’s ability to sustain activity over long periods of time?

A

Sustained activity results in working memory, as ACh neuromodulation consolidates memory in cortex while NE and DA generate patterns of working memory

34
Q

What is the role of NE and DA in maintaining working memory? What happens in the dlPFC if there is excess of NE and DA?

A

NE and DA neuromodulation sustain working memory
-NE increases responsiveness (increases signal)
-DA sculpts neuronal firing (decreases noise)
Excess NE/DA in times of stress disrupts neuromodulation leading to distractability
Likewise, low levels lead to drowsiness and non-alertness (ADHD)

35
Q

What are the major constituents of the basal ganglia? Where are these structures located?

A

Basal ganglia consists of masses of gray matter (nuclei) including:
Caudate
Putamen
Nucleus accumbens
Globus pallidus (internal-GPi/external-GPe)
Subthalamic nucleus (STh)
Substantia nigra (SN)
Ventral tegmentum
These structures are found in cerebral hemispheres surrounding the thalamus

36
Q

What is meant by the term striatum?

A

The striatum refers to the caudate plus the putamen, separated by the internal capsule

37
Q

Describe the sources of dopamine neuromodulation for the striatum.

A

Substantia nigra pars compacta (SNpc) contain pigmented cells that project to striatum

38
Q

What is a corticostriate (CS) loop?

A

CS loops are anatomically distinct loops between cortex, basal ganglia, and thalamus that allow parallel processing of affective, cognitive, and motor components of behavior

39
Q

What are the general functions of the direct and indirect pathways of CS loops? Which NTs are involved and how are these pathways regulated?

A

*Direct and indirect pathways select different strategies with indirect path inhibiting most responses and direct path facilitating the few appropriate ones - Dopamine (DA) activates direct pathways via D1 receptors and inhibits indirect pathways via D2 receptors in order to increase signal to noise ratio
Excitatory paths act via glutamate while inhibitory paths act via GABA

40
Q

What are the four known CS loops?

A

Visual, motivational, executive, motor/premotor

41
Q

What parts of the cortex are involved with the motivational loop? What are the general functions of the motivational loop?

A

Motivational loop projects info from vmPFC, OFC, ACC, amygdala, and hippocampus to nucleus accumbens/ventral striatum
Regulates motivational-emotional aspects of behavior (reward, feeding, addiction) by translating motivation into action through transferring reinforcing signals to motor/executive loops to form habits

42
Q

What parts of the cortex are involved with the executive loop? What are the general functions of the executive loop?

A

Executive loop projects info from dlPFC and association cortices to caudate
Form working memory and performs executive functions such as selecting movements, allocating attention, planning, organizing, regulating, monitoring goal oriented behavior

43
Q

What parts of the cortex are involved with the motor loop? What are the general functions of the motor loop?

A

Motor loop projects info from primary motor, premotor, supplementary motor, and somatosensory cortex to putamen
Involved with programming and initiation of internally generated movements as well as controling movement direction/scaling (velocity, amplitude, initiation, termination)

44
Q

What parts of the cortex are involved with the visual loop? What are the general functions of the visual loop?

A

Visual loop projects info from extrastriate cortex to caudate and then back through GP and thalamus to visual and PFC
Forms elaborate visual categories and integrates visual input into declarative/procedural learning

45
Q

Distinguish procedural memory from declarative and emotional memories.

A

Declarative memory - episodic memories processed in the hippocampus and consolidated into semantic memory on cortex
Emotional memory - fear conditioning by association of stimulus and aversion is processed/stored in amygdala
Procedural memory - non declarative, implicit, rigid, procedural, automatic memory involving cerebellum which combines learned movements to produce motor skill behavior and basal ganglia (CS loops) which form habits

46
Q

What are the three aspects of procedural memory?

A

Category representation - stimulus categories derived from association sensory cortex are linked to appropriate behaviors
Action selection - loops select and group neuronal populations that focus desired motor response
Instrumental and reward learning - conditioning behavior to novel cognitive emotional cues involves switching tasks - reinforced by DA

47
Q

What is the difference between declarative and procedural learning of visual categories?

A

Declarative (explicit) depend on hippocampus and prefrontal regions involved in working memory/executive attention
Procedural depend on visual CS loop which branches to executive and premotor loops to integrate with executive control to learn complex info, incidentally, without awareness - reinforced by DA

48
Q

What impact does dopamine neuromodulation have in action selection and instrumental/reward learning?

A

Phasic DA activity to striatum selects response from motivational, executive, and sensorimotor loops and combines them to form goals, actions, and movements

49
Q

Distinguish between instrumental and reward learning. What is the difference in their outcomes?

A

Instrumental (true procedural) learning involves goal and action with association of stimulus (seeing a ball) and response (kicking the ball) - after appropriate CS learning, task-related elements are sharpened and highlighted
Reward learning occurs when behavior is conditioned by association of stimulus with reward, mediated by motivational loop (vmPFC, OFC, nucleus accumbens)
- outcome drives behavior, rather than motor response itself, reinforced by DA

50
Q

What are the general actions of addictive drugs on the motivational CS loop?

A

Addictive drugs reinforce addictive behavior by transiently enhancing DA levels in accumbens, either by inhibiting DA uptake or enhancing its release

  • opioids facilitate DA release by inhibiting GABA inhibition in VT
  • nicotine stimulates VT dopamine cells via nicotinic cholinergic receptors
  • cocaine inhibits DA uptake at synapses in accumbens
  • *Hypofrontality (decreased PPFC/OFC) leads to decreased ability to inhibit accumbens leading to behavioral disinhibition
  • **Drug intake affects all CS loops
51
Q

What are the characteristics and causes of chorea?

A

Huntington’s chorea - involuntary jerky movements of face, tongue,, and limbs due to lesion of striatum and cortex leading to underactivity of indirect path (loss of striatal GABA neurons)

52
Q

What are the characteristics and causes of athetosis?

A

Athetosis - writhing movements of limbs - same loss of striatal GABA neurons as seen in chorea

53
Q

What are the characteristics and causes of hemiballismus?

A

Hemiballismus - failing of limbs due to lesion of subthalamus

54
Q

What are the characteristics and causes of Parkinson’s disease?

A

Parkinson’s - rest tremor, rigidity, inability to switch strategies, bradykinesia due to degeneration of pigmented dopaminergic neuron in substantia nigra causing reduced DA projection to dorsal striatum (causing involuntary movement) and ventral striatum (causing bradykinesia and cognitive dysfunction)

Organ Systems III (5 decks)

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