Sensorimotor Function Flashcards
What does hierarchically organised mean?
Operations commence from top down (motor output guided by sensory input).
What does functional segregation mean?
Each level of the sensorimotor hierarchy is composed of different units that perform different funcitons.
How does sensory input guide motor output?
Eyes, ears, organs of balance (posterior parietal cortex) skin and muscle receptors, all monitor body and feed responses back to sensorimotor circuit.
Describe the general model of sensorimotor function.
Association cortex - secondary cortex - primary cortex- brainstem - spinal
What role does the posterior parietal cortex play in sensorimotor function?
Provides spatial information about parts of body (where and where to be moved) and external objects and integrates this info.
Why is the posterior parietal cortex an associated cortex?
It receives information from more than one sensory system ( visual, auditory and somatosensory). Output goes to dorsolateral prefrontal cortex and secondary cortex areas.
What are two mays that parietal cortex can be damaged?
Apraxia - bilateral symptoms of difficulty making specific movements when requested, by caused by unilateral damage to left posterior parietal cortex.
Contralateral neglect. Inability to respond to stimuli on egocentric left of body. Associated with large lesions on right posterior parietal cortex.
What is the role of the dorsolateral prefrontal cortex?
Major cortical input from posterior parietal cortex and output to secondary, primary and frontal eye field. Complex voluntary movement
What is the input received from and what is the role of the secondary motor cortex?
Receives input from association cortex (parietal posterior cortex and dorsolateral prefrontal cortex) output to primary motor cortex.
Role involved in programming specific patterns of movements.
What are mirror neurons?
Neurons that fire when a goal directed movement is performed OR when you observe someone doing the same movement.
Provide possible explanation for social cognition (mapping others ideas etc. facilitates social understanding).
What is somatotopic organization?
Conventional view of primary motor cortex. When a specific part of the body is associated with a distinct location in the central nervous system.
What are current views of Primary motor cortex function?
Target of movement is more important than direction. Opposite movements from the same stimulation can be observed depending on the starting position. Means that signals from PMC can diverge massively, and sensorimotor system is plastic.
What is cerebellum and what does it do?
Contains more than half of the brains neurons
receives input from primary and secondary motor cortex
descending signals from brainstem nuclei feedback from motor response via somatosensory loop.
major role in learning sequence of movements.
What happens if the cerebellum is damaged?
lost ability to control, with precision, direction, force, velocity and amplitude of movements. Difficult to stand, balance, gait, eye movements.
What are the basal ganglia?
A group of structures found deep within the cerebral hemispheres.
includes the caudate, putamen, and globus pallidus in the cerebrum,
the substantia nigra in the midbrain, and the subthalamic nucleus in the diencephalon.
basal- near the base, or bottom, of the brain.
