Module 10 Flashcards
(125 cards)
What are the three principles of sensorimotor control mentioned in the text?
(1) The sensorimotor system is hierarchically organized. (2) Motor output is guided by sensory input. (3) Learning can change the nature and the locus of sensorimotor control.
How is the operation of the sensorimotor system compared to that of a large, efficient company?
Both are directed by commands that cascade down through hierarchical levels, with higher levels specifying general goals rather than specific plans of action.
What are the advantages of hierarchical organization in both the sensorimotor system and a large company?
Higher levels are left free to perform more complex functions, while lower levels execute more detailed tasks.
What characterizes the structure of both the sensorimotor system and a large company hierarchy?
They are parallel hierarchical systems, allowing control over lower levels through multiple paths.
What role does functional segregation play in the sensorimotor system and a large company hierarchy?
Each level is composed of different units (neural structures or departments), each performing a different function.
What is the main difference between sensory systems and the sensorimotor system in terms of information flow?
In sensory systems, information mainly flows up through the hierarchy, while in the sensorimotor system, information mainly flows down.
What role does sensory feedback play in directing responses in the sensorimotor system?
Sensory feedback plays an important role in directing responses, with most responses influenced by the sensory feedback they generate.
What are ballistic movements, and how are they influenced by sensory feedback?
Ballistic movements are brief, all-or-none, high-speed movements. They are not normally influenced by sensory feedback.
How are adjustments in motor output controlled during sensorimotor learning?
Many adjustments are controlled unconsciously by lower levels of the sensorimotor hierarchy without the involvement of higher levels.
What characterizes sensorimotor learning in terms of motor responses and conscious control?
During initial stages, individual responses are performed under conscious control; with practice, responses become organized into continuous sequences of action adjusted by sensory feedback without conscious regulation.
What are the two major areas of sensorimotor association cortex mentioned in the text?
The posterior parietal association cortex and the dorsolateral prefrontal association cortex.
What role does the posterior parietal association cortex play in sensorimotor control?
It integrates information about body position and external objects, directs behavior by providing spatial information, and directs attention.
What sensory systems does the posterior parietal cortex receive input from?
The visual system, the auditory system, and the somatosensory system.
Where does much of the output of the posterior parietal cortex go to?
It goes to areas of motor cortex located in the frontal cortex, including the dorsolateral prefrontal association cortex and various areas of secondary motor cortex.
What consequences can damage to the posterior parietal cortex produce?
Deficits in perception and memory of spatial relationships, accurate reaching and grasping, control of eye movement, attention, apraxia, and contralateral neglect.
Define apraxia.
Apraxia is a disorder of voluntary movement not attributable to paralysis or weakness, where patients have difficulty making specific movements, particularly out of context.
What is contralateral neglect?
Contralateral neglect is a disturbance of a patient’s ability to respond to stimuli on the side of the body opposite to the brain lesion, without simple sensory or motor deficits.
What is egocentric left?
Egocentric left is the deficit in responding to stimuli to the left of the patient’s own body, often observed in patients with contralateral neglect.
What is object-based contralateral neglect?
Object-based contralateral neglect is the failure to respond to the left side of objects, regardless of their position in the visual field.
How does unconscious perception manifest in patients with contralateral neglect?
Patients may exhibit unconscious perception by showing a tendency to look more in the direction of stimuli presented to their neglected side, or by demonstrating improved identification of fragmented drawings after exposure to complete versions they were not consciously aware of.
What are the two major areas of association cortex with important sensorimotor functions mentioned in the text?
The posterior parietal association cortex and the dorsolateral prefrontal association cortex.
What areas receive projections from the dorsolateral prefrontal association cortex?
Areas of secondary motor cortex, primary motor cortex, and the frontal eye field.
What types of activity do dorsolateral prefrontal neurons exhibit?
Some neurons show activity related to object characteristics or locations, while others show activity related to responses, firing before and during movement initiation.
What is the function of areas of secondary motor cortex?
They are involved in programming specific patterns of movements after receiving instructions from the dorsolateral prefrontal cortex.