Quiz 3 Flashcards
(65 cards)
0
Q
Basal Ganglia motor nuclei are divided into functional groups- input
A
Input zone of basal ganglia and destination of most pathways = corpus striatum
- caudate nuclei: input from association cortices & frontal lobe areas involved with eye movement
- putamen nuclei: input from 1 and 2 somatic sensory, visual, premotor and motor cortices, & auditory association areas
1
Q
Basal Ganglia- do what, where, what nuclei form it
A
- aid in regulation of UMN activity
- in telencephalon, diencephalon, mesencephalon
- nuclei: caudate, putamen, globus pallidus, substantia nigra, subthalamic nucleus
2
Q
What is the destination of axons from cerebral cortex? Where does the info go from here?
A
axons –> medium spiny neurons in caudate or putamen –> globus pallidus & substantia nigra pars reticulata
3
Q
Output of basal ganglia to…
A
pallidum:
- globus pallidus
- substantia nigra pars reticulata
4
Q
What is the corticostriatal pathway?
A
associations of cortex to basal ganglia traveling through subcortical white matter —> to the caudate or putamen
5
Q
The specialized areas of cortex maintained in corticostriatal pathway is evidence for:
A
staining the corpus striatum to reveal localization patterns:
- patches = light staining
- matrix = dark staining
- tracts
6
Q
Inputs to medium spiny neurons (6)
A
- corticocortical, corticothalamic, corticospinal tracts
- cerebral cortex
- other medium spiny neurons via axon collaterals
- local circuit interneuron of corpus striatum
- neurons from nuclei of thalamus
- brainstem nuclei
7
Q
Medium Spiny Neurons and Conductance; Firing and Movement
A
- have inward rectifying K+ conductances that close with depolarization
- to overcome inward K+ flow, neurons need a lot of excitatory input
- fire prior to movement occurring
- firing part of movement selection or even the decision to move toward a goal
8
Q
Simple Pathway of Basal Ganglia
A
multiple areas of cortex –> caudate/putamen –>
substantia nigra pars reticulata –> superior colliculus
OR globus pallidus internal –> VA/VL thalamus complex –> frontal cortex
9
Q
Sacades in Monkeys Pathway
A
before eye mov’t, firing of caudate –> signal to substantia nigra reticulata –> decrease tonic inhibition –> superior colliculus able to generate APs –> eye mov’t
10
Q
Principal Function of Basal Ganglia in Motor Control
A
- help initiate motor programs that express movement
- suppress competing motor programs
- via Focused Selection
11
Q
Circuits Within Basal Ganglia
A
- Direct - aids in initiation of movement
2. Indirect - increases tonic inhibition of globus pallidus internal segment and substantia nigra pars reticulata
12
Q
Look at Direct and Indirect Pathways!!!
A
flow charts
13
Q
Focused Selection
A
- when stimulated by cortex, entire unit both enhances suppression of competing motions and stimulates desired motion
- indirect and direct pathway functionally organized in center surround unit
- direct pathway within center and affects internal globus pallidus and substantia nigra pars reticulata
- indirect pathway surrounds direct and affects broad range of functional units
14
Q
Dopamine and Basal Ganglia: dopaminergic neuron location and synapse, NT and receptors and pathway
A
- dopaminergic neuron from substantia nigra pars compacta (loop with medium spiny neurons)
- synapse on neuron spine shafts to modulate response to cortex
- D2 receptors (indirect pathway and inhibitory): decrease cAMP
- D1 receptors (direct pathway and excitatory): increase cAMP
15
Q
Parkinson’s Disease: hyper or hypokinetic? signs/sx? caused by? results in?
A
- hypokinetic
- signs/sx: lack of facial expression, resting tremor, rigidity of extremities, lack of arm swing, shuffling steps
- caused by: loss of nigrostriatal dopaminergic neurons
- results in: more inhibition to UMN = less activity
- decreased substantia nigra pars compacta
16
Q
Huntington’s Disease: hyper or hypokinetic? signs/sx? caused by? results in?
A
- hyperkinetic
- signs/sx: changes in mood and behavior, changes in memory, choreiform movements (jerky mov’t)
- caused by: autosomal dominant defect in Huntington gene with increase in nucleotide repeats within gene
- results in: degeneration of medium spiny neurons in indirect pathway = decrease size of caudate and putamen
17
Q
Hemiballismus- damage to? sign/sx? does what to stimulation?
A
- damage to subthalamic nucleus
- sudden involuntary limb movement
- increases stimulation to UMN
18
Q
Cerebellum: functions and structure
A
Functions:
- modify activity of UMN
- detect and reduce error of movements during the movement and during motor learning
Structure:
- 2 gray matter structures = cortex and deep cerebellar nuclei
- deep cerebellar nuclei = dentate nucleus, 2 interposed nuclei, fastigial nucleus
19
Q
3 Parts to Cerebellum
A
- cerebrocerebellum
- spinocerebellum
- vestibulocerebellum
20
Q
Cerebrocerebellum: input from what? function? damage causes?
A
- input from cortex
- function: regulate complex and skilled movements, esp. planning and execution of complex spatial and temporal sequences
- damage: difficulty with skilled sequences of motor movements (speech)
- largest and well developed in primates and humans
21
Q
Spinocerebellum: input from? divisions and functions? damage causes?
A
- input from spinal cord
- divided into median and paramedian areas
- median: called vermis, function- involved w/ proximal muscle movements and eye movement
- paramedian: function- involved w/ movement of extremities
- damage: wide based gait, shuffling movements, dysiadochokinesia (difficulty w/ rapid alternating movements), dysmetria (over or under reaching), intention tremors
22
Q
Vestibulocerebellum: input from? located in? functions? damage?
A
- input from vestibular nuclei
- located in flocculus and nodulus
- function: vestibulo-ocular reflex, posture and equilibrium
- damage: impairs ability to stand upright and maintain gaze (nystagmus), can have reduction in muscle tone (vestibular nuclei damage)
23
Q
Cerebellum Pathways (3)- efferent or afferent? travel?
A
- superior cerebellar peduncle (brachium conjuctivum) = 2 efferent pathways
- deep cerebellar nuclei –> dorsal thalamus –> UMN in primary and premotor cortex
- directly to UMN in superior colliculus - middle cerebellar peduncle (brachium pontis) = afferent path and one of largest pathways in brain
- contralateral pontine nuclei –> cerebellum - inferior cerebellar peduncle (restiform body) = both afferent and efferent
- afferent runs from vestibular nuclei, spinal cord, parts of brainstem
- efferent runs to vestibular nuclei and reticular formation
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Projections to Cerebellum (8)
1. frontal and parietal cortex
2. vestibular nuclei
3. vestibular axons from CN 8
4. external cuneate nucleus
5. dorsal nucleus of Clarke
6. inferior olivary nucleus- input from red nucleus, reticular formation, spinal cord, gap junctions
7. mesencephalic nucleus of trigeminal
8. visual and auditory signals
25
Cerebral Cortex and Cerebellum- contralateral or ipsilateral?
cerebellum = ipsilateral!
| cerebral cortex = contralateral!
26
When from frontal/parietal cortex --> pontine nuclei -->??
transverse pontine fibers cross midline in middle cerebellar peduncle --> cerebellar cortex/deep nuclei
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Projections from 3 Parts of Cerebellum
1. cerebrocerebellum projects to dentate nucleus = help plan volitional and planning movements
2. spinocerebellum projects to interposed and fastigial nuclei = help control motor execution
3. vestibulocerebellum projects to vestibular complex = help with balance and movements of eyes, head, neck movement
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Cerebrocerebellar Pathway multiple projections (3)
1. to dentate nucleus --> thalamus --> premotor and associational cortices of frontal lobe
2. branches to red nucleus --> inferior olive
3. to non motor areas of cortex (closed loop)
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Cerebellum has somatotropic organizations similar to spinal cord: deep cerebellar nuclei to --> and do what
1. fastigial nuclei --> inferior cerebellar peduncle --> nuclei of reticular formations and vestibular complex
* forms medial tracts that govern axial and proximal limbs
2. interposed nuclei --> superior cerebellar peduncle --> thalamus neurons that stimulate frontal lobe motor regions for limbs
* primates also have branches from interposed nuclei to magnocellular neurons of red nucleus
3. dentate and interposed nuclei --> superior cerebellar peduncle --> superior colliculus
30
There cerebellum has intricate circuit loops that serve to modify output: what are the main neurons involved?
1. mossy fibers
2. parallel fibers
3. Purkinje fibers
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Mossy Fibers: axons from where? excite or inhibit? synapse on?
- axons from pontine nucleus and other brainstem areas
- excitatory
- synapse on: contralateral deep cerebellar nuclei, granule cells (highest #)
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Parallel fibers- axons from where? excite or inhibit? do what?
- axons from granule cells
- excitatory
- contact numerous Purkinje cells
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Purkinje cells- excite or inhibit? project to what? contact what?
- GABAergic = inhibitory
- project to deep cerebellar nuclei
- contact numerous parallel fibers
- only output of cerebellar cortex
34
Modifiers to Purkinje Fibers (and other)
1. climbing fibers
2. basket cells- inhibitory on Purkinje cell bodies
3. stellate cells- inhibitory on Purkinje cell dendrites
* golgi cells modify granule cells
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Climbing Fibers: from where? do what? excite or inhibit? have what?
- from inferior olive
- modify influence of parallel fibers on Purkinje fibers --> modify deep cerebellar nuclear cells
- excitatory
- have gap junctions to allow synchronized effects
36
What makes up Cortical Inhibitory Loop and Deep Excitatory Loop? These loops do what?
Cortical Inhibitory Loop = Purkinje Fibers
Deep Excitatory Loop = Mossy Fiber and Climbing Fiber
* regulation during movement and long term changes in motor learning
37
Purkinje Fibers: integrate input from where?
1. interneurons: basket and stellate cells
2. climbing fibers (from inferior olive)
3. parallel fibers (from granule cells)
38
Inferior Olive: provides short term and long term what?
- short term sensorimotor adaptation (error correction) via inputs received)
- long term motor learning via modulation of cerebellar processing from climbing fiber activation
39
Purkinje Fibers and Deep Cerebellar Nuclear Cells are tonically active at rest: what changes them or what do they respond to?
- neuronal activity within them changes as movement occurs
| - responds to changes in: contraction/relaxation, joint position, direction of movement
40
Injury to Cerebellum
- disruption in immediate error correction
- cerebellar ataxia: jerk and imprecise movements
- movement errors are ipsilateral
- due to topographic organization, damage to cerebellum can cause very specific effects
41
Summary of Cerebellum
- involved in error detection and coordinating smooth movements
- involved with motor learning
42
Components of Visceral Motor System and cord levels; Major locus of central control and its modulated by
1. SNS: thoracolumbar T1-L2
2. PSNS: craniosacral S2-S4
3. Enteric: gut, can act independently
* **locus of control: HYPOTHALAMUS modulated by amygdala, hippocampus, insula, cortical regions in ventral and medial frontal lobe
43
The Function of Visceral Motor System is Governed By:
1. descending pathways from hypothalamus and reticular formation
2. preganaglionics in brainstem and spinal cord
3. lower autonomic motor neurons in ganglia outside of CNS
44
Distinctive Features of Autonomic System (3)
1. LMN located outside CNS
2. cell bodies of SNS in ganglia near spinal cord, cell bodies of PSNS embedded in plexi near/on organ
3. motor axons are highly branches, less differentiation, many synaptic terminals, NTs travel long distances
45
Hypothalamus: location, integrates info from (4), diverse functions (4), overarching function(4)
- Location: base of brain (forebrain) with many nuclei
- Integrates: forebrain, brainstem, spinal cord, chemosensitive neurons
- Diverse Functions: control blood flow, regulate energy metabolism, regulate reproductive activities, coordinate threatening situations
- Overarching Functions: receive sensory and contextual info, compare this info with biological set point, activate different areas, restore homeostasis or allostasis
46
Distinct Hypothalamic Nuclei
longitudinal regions: periventricular, medial, lateral
| anterior posterior regions: anterior, tuberal, posterior
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Anterior Periventricular Nuclei (2)
1. suprachiasmatic nuclei: receives retinal input, drives circandian rhythms
2. scattered periventricular neurons: releasing/inhibiting factors for anterior pituitary, endocrine system involvement
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Medial Tuberal Nuclei
1. paraventricular nuceli/supraoptic nuclei: posterior pituitary involvement, secrete oxytocin and ADH, H2O balance
2. other nuclei connected to reticular formation and paraventricular nuclei
3. other nuclei connected to preganglionics and paraventricular nuclei
4. dorsomedial/ventromedial nuclei: feeding, reproduction/parenting, thermoregulation, H2O balance, receive input from limbic system and autonomic sensory system
49
Sympathetic NS: clinical manifestations, activity of what?
- Clinical Manifestations: pupils dilate, eye lids retract, skin and gut vessels vasoconstrict, bronchi dilation, HR and force of contraction increase
- increased activity of adrenal medulla = releases NE/Epi
50
Sympathetic NS: preganglionics
- T1-L2 intermediolateral column --> lateral horn
- paravertebral = innervate chain ganglia along spinal cord
- prevertebral = in splanchnic nerves (longer) to cardiac, celiac (foregut stomach or duodenum and up), superior mesenteric (midgut goes through transverse colon), inferior mesenteric (hindgut and to end)
- neurons are primary/LMN of SNS
51
Parasympathetic: preganglionics (brainstem nuclei, sacral)
- brainstem nuclei: Edinger Westphal nucleus in midbrain innervates ciliary ganglion to mediate pupil dilation, superior/inferior salivatory nuclei in pons/medulla innervates salivary glands and tear production, nucleus ambiguus in medulla innervates autonomic motor and cardioinhibitory, dorsal motor nucleus of vagus nerve in medulla innervates glands dorsally and motor ventrally
- sacral S2-S4: travel in splanchnic nerve and innervate lower 1/3 of colon/bladder/repro organgs
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PSNS: Clinical Manifestations
- pupils constrict, HR and force of contraction decreases, peristalsis increases, promotes urination
- ganglia are found in/near end organs with few dendrites
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Most organs receive input from both systems except what receives only SNS:
- sweat glands
- adrenal medulla
- piloerector muscles of skin
- most arterial blood vessels
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Enteric Nervous System: neurons in gut wall, specific organization
- Neurons: local neurons and centrally projecting sensory neurons, local circuit neurons, motor neurons
- Specific Organization: Myenteric/Auerback's plexus controls gut muscles, Submucous/Meissner's plexus control chemical monitoring and secretions
55
Sensory Components of Autonomic System: where are they? through which system? referred pain?
- in dorsal root ganglion
- through sympathetics
- referred pain: many second order neurons in dorsal horn are part of anterolateral system which receives crude pain and mechanosensory input from superficial areas
- nucleus of solitary tract: central structure in medulla that receives visceral sensory info and distributes it accordingly
56
Sensory Cranial Nerves for Autonomic System
Glossopharyngeal and vagus nerves:
- general visceral sensations- thorax, upper abdomen, head, neck
- afferents to nucleus of solitary tract
- sensory fibers limited info sent consciously, but painful stimuli is consciousness
57
Caudal vs. Rostral Part of Nucleus of Solitary Tract and info projected to
- caudal: controls reflexive actions of ANS
- rostral: control gustatory relay
- info projected to parabrachial nucleus to higher brain areas
58
SNS pregang and postgang NTs and receptors
Pregang NT = Ach w/ nicotinic receptors (fast ionic)
| Postgang NT = NE/Epi w/ adrenergic alpha and beta receptors (slow)
59
PSNS Pregang and Postgang NT and receptors
Pregang NT = Ach w/ nicotinic receptors
| Postgang NT = Ach w/ muscarinic receptors (M1-gut, M2-CV, M3-smooth muscle, glands, etc)
60
Horner's Syndrome- system? symptoms?
- damage to SNS of head and neck (T1-T3) connecting hypothalamus and reticular formations to preganglionics
- symptoms: decreased diameter of pupil (miosis), droopy eyelid (ptosis), sunken appearance (enophthalamos), decreased sweating, increased body temp, flushing
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Obesity- ghrelin, leptin
- ghrelin: secreted by stomach to stimulate hunger
- leptin: adipocytes to stimulate satiety
- mutations in leptin, leptin receptor, or MCR4 genes --> decreased satiety and failure to regulate food intake based on gastric distension, pain, plasma osmolarity
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Cardiovascular System: receptors
- baroreceptors: elastic in heart, major blood vessels
- chemoreceptors: ppO2 and CO2 in carotid bodies
- vagus and glossopharyngeal nerve --> nucleus of solitary tract --> hypothalamus
- SNS increases HR and vasodilate
- PSNS decreases HR and vasoconstrict
63
Bladder-SNS and PSNS activity
- PSNS helps with contraction of bladder/empyting
- SNS relaxes smooth muscle and internal sphincter
- when full --> decrease PSNS, increase SNS causing bladder to contract and internal sphincter to relax --> voluntary control of external sphincter
- during emptying --> increase PSNS, inhibit lower somatic neurons of external sphincter
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Sexual- PSNS and SNS
- PSNS: dilation of arteries, relaxation of sinusoidal spaces, excitatory input to secretions, NO mediates smooth mm relaxation
- SNS: vasoconstrict and loss of erection
- somatic component: excitatory for ejaculation and contract perineal for organsm
