motor control

Question 1

neuromuscular junction

Answer 1

specialized synapses between the nervous system and muscle fibers

Question 2

lateral corticospinal motor tract

Answer 2

involved in fine movement of distal limb muscles (arms, hands, fingers, lower leg and foot)

tract crosses entirely from one side of the brain to the opposite side of the body (contralateral)

Question 3

medial motor tract

Answer 3

involved in control of movements of the trunk and proximal limb muscles

involved in posture and bilateral movements

projects both contralaterally and ipsilaterally

Question 4

cerebellum motor control

Answer 4

plays an important role in coordinating timing of muscle movement, planning movement and learning motor skills

organized into 3 main divisions that each receives a distinctive type of info a sends out input to distinct portions of the nervous system

info flowing through these cerebellar loops allows it to modulate motor processing

movements that are not modified once they have been started

Question 5

vestibulocerebellum

Answer 5

damage causes difficulty with balance and postural instability

Question 6

spinocerebellum

Answer 6

damage causes difficulty with smooth muscle control of movement and movement of proximal muscles

Question 7

cerebrocerebellum

Answer 7

damage causes difficulty with the regulation of highly skilled movement that requites sensorimotor learning

Question 8

cerebellar ataxia

Answer 8

difficulties in coordinating movement after cerebellar damage

tradition test: patient touches their nose and then neurologist’s finger

occurs when activity of agonist and antagonist muscles are not coordinated

disrupts coordination of multi-joint movements. to compensate patients will move of join at a time in serial manner

difficulties in sensory motor learning after damage to lateral portions of the cerebellum.

Question 9

agonist

Answer 9

contracts during movement

Question 10

antagonist

Answer 10

relax/lengthen during movement

Question 11

forward model theory of cerebellar function

Answer 11

theory argues that the cerebellum helps predict the sensory consequences of motor plans

forward models not influenced by feedback from periphery

Question 12

subcortical nuclei in the basal ganglia

Answer 12

caudate nucleus
putamen
nucleus accumbens
globus pallidus
substantia nigra
subthalamic nucleus

Question 13

roles of the basal ganglia

Answer 13

setting the motor system with regard to posture

preparing the nervous system to accomplish a voluntary motor act

acting as an autopilot for well-learned sequential movements

controlling the timing and switching between motor acts

because they receive both motor and nonmotor info, the basal ganglia are also thought to assist in motor planning and learning

movements that take time to initiate or stop

Question 14

theories of the basal ganglia function

Answer 14

1. the basal ganglia facilitate the synchronization of cortical activity underlying the selection of appropriate movements while inhibiting inappropriate ones
2. the basal ganglis chunch individual actions into coordinated, stereotyped and habitual units of action
3. the basal ganglia aid the ability to execute movements with varying levels of vigor

Question 15

direct route of the basal ganglia

Answer 15

contributes to sustaining/ facilitating ongoing action

Question 16

indirect route of the basal ganglia

Answer 16

important for supressing unwanted movement

works in opposition of the other

Question 17

parkinsons

Answer 17

results from damage to the cells of the substantia nigra

loss of dopamine neurons

tremors - rythmic, oscillating movements
akineria - inability to initiate spontaneous movement
bradykinesia - slowness of movement

Question 18

what does neuron death in the substantia nigra cause

Answer 18

inadequate input to the basal ganglia

causes overactivation of th indirect pathway

increases activity in the internal portion of the globus pallidus

inhibits the thalamus and decreases motor activity

Question 19

treatment for parkinsons

Answer 19

levodopa

deep brain stimulation

Question 20

levodopa

Answer 20

cannot give dopamine directly

monoamine oxidase (MOA-B) inhibitors

Question 21

deep brain stimulations (DBS)

Answer 21

aerobic exercises and behaviour intervention

thalamonoty or pallidotomy

grafting of fetal tissue to the striatum

Question 22

huntington’s disease

Answer 22

involuntary, uncontrollable and undesired movements

chorea
dystonia

Question 23

chorea

Answer 23

rapid, jerky movements that appear coordinated but are performed involuntary in an irregular manner

Question 24

dystonia

Answer 24

slower movements causes by increased muscle tone and contractions that lead to abnormal posture

Question 25

huntingtons disease indirect pathway

Answer 25

loss of striatal neurons to globus pallidus external globus pallidus is no longer inhibited increases inhibition of the subthalamic nucleaus the internal globus pallidus is not excited so output is reduct. this lessens inhibitions of the thalamus which increases cortical motor activity

Question 26

huntington's etiology

Answer 26

an inherited neurological disease resulting in striatum degeneration produces abnormal movements, cognitive deficits and psychiatric symptoms caused by a rare, autosomal dominant disease gene produces mutant huntingtin protein causing striatum atrophy symptoms typically manifest between 30-45 years of age it involves a slow decline for 10-15 years and eventually leads to death

Question 27

tremors

Answer 27

tremors - rythmic, oscillating movements

Question 28

akineria

Answer 28

akineria - inability to initiate spontaneous movement

Question 29

bradykinesia

Answer 29

bradykinesia - slowness of movement

Question 30

huntington's treatment

Answer 30

no cure, treatments can provide some symptom relief tetrabenazine or neuetrabenazine (deplete or block dopamine transmission

Question 31

tourettes

Answer 31

main symptom is vocal and/or motor tics that fluctuate in severity relatively rare disorder that manifests in childhood definitive neural substrate or cause has not been found aspects of the disorder point to dysfunction of the basal ganglia and associated cortical-striatal-thalamic-cortical brain circuitry nature of tics potentially represents an inappropriate from of habit learning (basal ganglia)

Question 32

forms of tics

Answer 32

simple motor tics that involve just one portion of the body more complex tics that involve several muscle groups and seem more purposeful can include echolalia and coprolalia

Question 33

echolalia

Answer 33

repeating things just said

Question 34

coprolalia

Answer 34

intypical speech

Question 35

what is the major role of cortical regions in motor control

Answer 35

planning and guiding skilled movements movements that require linking sensory inputs with motor outputs

Question 36

how do cortical regions support a range of motor abilities

Answer 36

picking up an object producing a gesture in response to a verbal command moving the eyes to explore the image of a face

Question 37

where are regions of motor control distributed

Answer 37

across lateral and medial parts of the brain

Question 38

primary motor cortex

Answer 38

thought to control the force and or direction with which the motor plans are executed provides the command signal to drive motor neurons to make muscles more

Question 39

premotor region, supplementary motor complex and frontal eye fields

Answer 39

involved in the specifying, preparing and initiating of a movement

Question 40

anterior cingulate cortex

Answer 40

important for selecting among particular responses and monitoring whether the execution of those actions occurred apropriately contains many distinct subregions, each of which contributes to particular cognitive functions (activated across a large range of tasks - plays a role in allowing the motor system to generate and select a response and then evaluate the consequences - feedback systems - did this plan work, and if not how will i fix it for next time (learning from your actions) - most involved when an action is novel of requires cognitive control, such as when a well-engrained response must be overwritten

Question 41

parietal regions

Answer 41

involved in linking movements to extrapersonal space and sensory info as well as linking movements to meaning what are my senses telling me sensations, somatosensory areas

Question 42

what happens when the primary motor cortex is damaged

Answer 42

a person cannot control the force of which muscles are exerted severe cases can result in hemiparesis (weakness)

Question 43

organization of the primary motor cortex

Answer 43

main: the motor cortex is organized so that different subregions of motor cortex control action of specific portions of the body homunculus organization alternative: the motor cortex is organized with regard to action relevent for survival. extended stimulation can lead to coordinated movements.

Question 44

motor plans

Answer 44

are abstract representations of intended movements brain generates the action plan before the movement starts the supplementary motor complex comes up with the motor plan at the most abstract level then premotor areas code for the types of actions that must occur to meet that motor plan (how to execute the motor plan) primary motor regions execute the commands - send the signal to the body

Question 45

coarticulation

Answer 45

forming the next sentence before the first one ended

Question 46

supplementary motor complex

Answer 46

involved with planning, preparing and initiating movements (activity in this region precedes motor action sequence and order in which actions occur SMC projects to both the ipsilateral and the contralateral motor cortex, as well as the contralateral SMC - distinct from primary motor cortex in which activation is predominantly observed contralateral to what is moving

Question 47

what are the three sub-regions of the SMC

Answer 47

anterior located pre-SMA Supplementary eye field posteriorly located SMA

Question 48

anterior located pre-SMA

Answer 48

involved in selecting what actions should be implemented initial planning

Question 49

supplementary eye field

Answer 49

involved in the planning of eye movement

Question 50

posteriorly located SMA

Answer 50

involved in planning movement of body parts (other than the eyes)

Question 51

right inferior frontal cortex

Answer 51

suggested to play a role in interupting or inhibiting motor actions - often assed via the stop-signal paradigm - the larger tissue loss the more difficulty in response inhibition - stopping an action the region is also activated when people have to push a button twice rather than aborting a response - perhaps plays a role in altering actions based on the current environmental context rather than inhibiting actions

Question 52

parietal lobe

Answer 52

sensation superior regions interface between movement and sensory info (coordinated movement between these two) - damage causes inability to guide limbs in a well-controlled manner inferior regions contribute to the ability to produce complex, well-learned motor acts - damage to these regions leads to a disorder known as apraxia

Question 53

apraxia

Answer 53

an inability to perform skiled, sequential, purposeful movement that cannot be accounted for by disruptions in more basic motor processes commonly observed after a stroke, TBI and in people with neurodegenerative disorders most typically observed after parietal or frontal lesions of the left hemisphere