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Year 2: Neurobiology II > Lecture 4: Motor Control pt. I > Flashcards

Lecture 4: Motor Control pt. I Flashcards

1
Q

what is motor control

A

process of initiating, directing, and grading purposeful volitional movement

responding actions to environmental stimuli (most of the nervous system components for sensory and integrative function)

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2
Q

top down vs bottom up motor control

A

top down = do not need external stimuli

bottom up = respond to external stimuli

CPGs = still work w/o CNS control

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3
Q

how do reflexes work with motor control

A

stimulus is sent to the CNS

instead of getting interpreted with cognition, CNS directly interacts with motor neurons causes immediate action

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4
Q

describe the hierarchial organization of motor control

A

4 levels

all levels above level 1 = UMN system

neurons in level 1 = LMN system (SC)

2 side loops = basal nuclei and cerebellum

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5
Q

what are the 4 levels of hierarchy of motor control

A

level 1 = SC
level 2 = brain stem
level 3 = motor cortex
level 4 = association cortex

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6
Q

what is functional segregation related to motor control

A

various functional regions in nervous system for motor control

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7
Q

what are the components of level 4 of motor control hierarchy (multimodal association cortex) (6)

A

cingulate motor area (part of limbic system)

posterior parietal cortex (Brodmann 5, 7)

Frontal eye field (Brodmann 8)

Language areas
-Broca’s (Brodmann 44,45)
-Wernickes (Brodmann 22)

prefrontal cortex for functional execution

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8
Q

what is the function of the cingulate motor area in motor control

A

reciprocal projections with many structures that have different functions/send different information

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9
Q

what are the reciprocal projections of the cingulate motor area and their function

A

L dorsolateral prefrontal cortex = motor planning and execution (working memory)

oribitofronal cortex = collecting/summarizing results of motor programs

cingulate motor area = calculating reward of motor program

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10
Q

describe how the cingulate motor area calculates “reward” of a motor program performed

A

emotion related behaviors; motivation vs aversion

making the decision of if it is worth doing something or not

alternate motor control theory = invest and reward

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11
Q

what are the functions of the posterior parietal cortex in motor control related to vision

A

Dorsal visual pathways
- process context and spatial rep of objects (where)
-visuomotor transformations = how to respond to visual stimuli (integration of perception to action)

specialized area for reach and grasp (lateralized to L hemisphere)
- process object size
-orientation
-hand matching

saccadic eye movements = hand eye coordination

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12
Q

functions of the posterior parietal cortex in regard to motor control

A

functions are lateralized

R = bilateral attention scanning and spatial cognition
- L side hemineglect occurs when R side is damaged; ischemic vs hemorrhagic stroke

L = praxis and language
- L side damaged = apraxia

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13
Q

what are the components of level 3 motor control

A

unimodal association cortex made up of:
-supplemental motor area - Brodmann 6
-premotor cortex - Brodmann 6 dorsal/ventral

primary motor cortex (M1) - Brodmann 4

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14
Q

where is the SMA

A

medial frontal lobe

anterior to M1

has a gross topographic distribution

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15
Q

What areas of the brain does SMA “talk to” in regard to motor control; what guides its function?

A

directly “talks” with cingulate motor area

performance is guided by internal cues - OPEN LOOP/top down; no sensory input required

coordinates sequential tasks

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16
Q

what areas of the brain are activated in the brain when performing simple motions, complex motions, and imagery of complex motions respectively

A

simple motion = unilateral M1/S1 activation

complex motion = unilateral M1/S1 and bilateral SMA

imagery of complex motion = bilateral SMA

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17
Q

functions of SMA in motor control

A

coordination of bimanual movements during complex movements

active during motor imagery (mental rehearsal of bimanual and sequential tasks)

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18
Q

locations of primary motor area

A

dorsal to ventral along brodmann area 6

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19
Q

functions of premotor cortex in motor control

A
  1. signals the preparation for movement - via motor set neurons
  2. signals correct and incorrect actions
  3. signals various sensory aspects associated with motor actions - via mirror neurons
  4. distinguishes the same movement based on behavioral context (i.e. picking up full vs empty cup)
  5. relies on external sensory input for movement (conext) - CLOSED LOOP
  6. motor imagery WITH external stimuli; bottom up
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20
Q

what are mirror neurons

A

where perception and action integrates

NOT in occipital lobe

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21
Q

sensorimotor pathway of mirror neurons and it’s function

A

somatic motor

different neuron for different movement patterns
- strictly congruent = only respond to 1 stimuli
- broadly congruent = respond to multiple

function = understanding intention of the movement (learning)

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22
Q

emotion pathway of mirror neurons

A

self and social cognition

recognizing cultural conflict

individualism vs collectivism

helps humans understand one another

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23
Q

what happens if the sensorimotor and emotion pathways of mirror neurons are not integrated in daily life

A

autism spectrum disorder

24
Q

functional impairment of the association cortex results in what

A

apraxia

25
Q

apraxia definition

A

cant perform skilled or learned movements with intact sensory or motor system (loss of mirror neiron connections)

26
Q

ideational apraxia; it is a loss of what

A

know the tools but cant use them

loss of action sequencing

27
Q

ideomotor apraxia

A

know how to perform an activity but cant perform the actual activity

28
Q

limb kinetic apraxia

A

unable to make precise, independent but coordinated movx ements

29
Q

apraxia is mainly related to what 2 parts of the brain

A

left premotor (6) and posterior parietal cortex (5)

compromised mirror neurons

30
Q

classic model of the homunculus of M1

A

lower limb to tongue in an inverted representation

31
Q

updated model of the homunculus of M1 as well as the clinical significance of this new model

A

3 symmetric concentric topographic representation

spaced by 3 cognitive control regions

clinical significance:
- poor foot, hand, and tongue fine motor control recovery
- all UMN neurons control patterns of motion, not contraction of a single mm

32
Q

describe the motor neuron distribution in M1

A

chimeric distribution of M1

gross order with gradient distribution (overlap)

not like S1 which is still strictly represented in homunculus

33
Q

describe the neuronal firing in M1

A

fire 5-100msec before onset of movement

fastest region when stimulated = existing mechanisms for direct LMN control

34
Q

M1 neurons encode what info

A

force of movement
extent of movement
speed of movement
direction of movement

35
Q

what defines the intention of the movement in M1

A

pyramidal cells

columnar of neurons oversee specific behavior

36
Q

describe the S1 homunculus

A

strictly follows topographic representation of body

37
Q

function of S1 in motor control

A

direct projection to M1

adjusts movement constantly

38
Q

What are the components of the corticobulbar and corticospinal tracts

A

monosynaptic M1 neurons

disynaptic neurons

**S1 does NOT contribute much to human corticobulbar and corticospinal tracts

39
Q

describe monosynaptic M1 neurons and their function

A

develop postnatally

located caudal to M1, anterior bank of central sulcus

directly synapse with LMN for fine motor control

40
Q

describe disynaptic neurons and their function

A

developed prenatally, through interneurons to LMN

located in:
-rostral M1
-dorsal and ventral PM/SMA (brodmann 6)
-2 from cingulate gyrus
-posterior parietal lobe (Brodmann 5)

41
Q

describe the path for the descending cortical tracts for motor control

A

through the posterior limb of the internal capsule

rotates while descending

gross topography maintained above the pons

somatotopy = face to LE from anterior to posterior; rotation from medial to lateral

42
Q

where are the nuclei of the corticobulbar tract and their function with motor control

A

motor nuclei in brainstem

6 nuclei = w/o CN III/IV/VI for neck/head mm

brainstem motor control function = red/reticular/vestibular nuclei; generally inhibition

43
Q

describe the path for the corticospinal tract

A

travels all SC levels

has collateral terminals for brainstem motor nuclei

44
Q

where are the decussations for the corticospinal tract and where do the fibers continue afterward

A

70-90% decussate in pyramid (caudal medulla) = for contralateral body control

these tracts descend in the lateral funiculus and form the lateral corticospinal tract for extremity flexors and fine motor control

the rest do not decussate and continue ipsilaterally

some go to anterior funiculus and form the medial corticospinal tract for bilateral trunk mm and postureal control

the rest go to the ipsilateral funiculus to form the ipsilateral lateral corticospinal tract for extremity flexors and fine motor control

45
Q

level 2 of motor control is made up of what areas of the brain and what are their associated tracts

A

brainstem

midbrain = rubrospinal tract

pons = pontine reticulospinal tract and vestibulospinal tract (lateral and medial)

medulla = medullary reticulospinal tract

46
Q

function of rubrospinal tract in motor control and general pathway

A

fine motor control; flexors of UE and trunk

decussates in midbrain

descends into lateral funiculus of SC

47
Q

learning a new skill goes through what circuitry and involved what fibers

A

through the red nucleus-inferior olivary nucleus-cerebellum circuitry

climbing fibers are involved

48
Q

general functions/path of reticular nuclei in motor control

A

generally bilateral projections through anterior funiculus

pontine reticulospinal tract = all spinal levels, controls extensors (posterior control)

medullary reticulospinal tract = all splinal levels, controls flexors (anterior control)

49
Q

paths of the vestibulospinal tracts and what they control

A

lateral vestibulospinal tract = ipsilateral anterior funiculus for proximal extremity extensors

medial vestibulospinal tract = bilateral anterior funiculus for neck/upper trink extensors

50
Q

which tracts descend the whole SC

A

pontine reticulospinal tract

lateral vestibulospinal tract

medullary reticulospinal tract

51
Q

how far does the medial vestibulospinal tract descend

A

into C/S (neck)

52
Q

how far does the rubrospinal tract descend

A

to UE

53
Q

what is decerebrate posture

A

** without cerebral peduncle; lesion BELOW RED NUCLEUS

no functional rubrospinal tract and corticospinal tract

no flexor tones

no inhibition of level 2 motor control system

UE and LE both in EXTENSION synergies

54
Q

what is decorticate postire

A

** without cerebral cortex; lesion ABOVE RED NUCLEUS

upper limb flexors activated by rubrospinal tract without cerebral cortex inhibition

UE in FLEXION synergies

LE in EXTENSION synergies

55
Q

why do both decerebrate and decorticate postires have extension synergies in LEs

A

in both cases the vestibulospinal tracts are active

BLEs are in extension

Year 2: Neurobiology II (10 decks)

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