Motor Systems In The Brain

Question 1

Classification of movement

Answer 1

1- simple reflex- stretch reflex knee jerk, mediated at the level of spinal cord
2-posture and postural change - standing , balancing
3- locomotion- walking,running
4-sensory orientation- head turning ,eye fixation
5- species specific action patterns - ingestion courtship escape defence grooming gestures
6- acquired skills- speech dressing , painting driving sports

Question 2

Control of movement

Answer 2

Motor output comes from the motor cortex
Projects through pyramidal tracts to spinal cord, where it synapses with peripheral motor neurones
Other pathways run parrelell from cortex basal gangalion and cerebellum via brain stem and spinal cord
- these ru,n outside the pyramidal tract and are called the extrapyramidal system

Question 3

Spinal motor pathways

Answer 3

Pyramidal tract- control most of our fine movements
Testospinal Tracy - coordinating head and eye movements
Cestibulospjnal tract
- influences postural muscles
Reticulospinal tract-projects from the reticular formation - inhibition or facilitation of movement

Question 4

Motor control systems in the cortex

Answer 4

Primary motor cortex -source of pyramidal tract neurones
Supplementary motor cortex
- conception and ignition of movement - lesions cause defects in voluntary movement or speech
Pre motor cortex - important in moto coordination - lesions cause impairments in stability of stance gait and hand coordination

Question 5

Motor control systems outside the cortex

Answer 5

Cerebellum -controls neural programs for execution of skilled movement
Basal gangalion - basal ganglia -a group of subcontinental forebrain nuclei - modulate patterns of moto activity - provide fine motor control

Question 6

Functional dissociation

Answer 6

Area V4 - colour processing
.individual neurones in v4 respond to a variety of wavelengths
Damage to =4 achromtopsia - inability to perceive colour patients see the world in black and weight inability to imagine or remember colour vision otherwise normal
Area v5 movement perception neurones respond to move t damage to v5 inability to perceive movement uneffected by colour perception object recognition etc
Able to judge movement of tactile or auditory stimuli

Question 7

Auditory processing

Answer 7

Processing originally thought to be in auditory cortex immediate stages only stepping stones but auditory discrimination possible in a sense of auditory cortex
Therfore initial processing occurs in pons and the thalamus auditory cortex analyses complex aspects of sound dorsal stream parietal lobe spatial analysis ventral stream temporal lobe component analysis

Question 8

The vestibule ocular reflex

Answer 8

As head riatates eye moves to compensate maintaining relative position
Occurs even with eyes closed not dependent on visual input
Depended t of vestibular input