Sensorimotor System Flashcards
Why is the sensorimotor system is hierarchically organized - apart of the three principles of sensorimotor function #1
Organized like a large company
President (association cortex) gives direction to lower levels
Lower levels (motor neurons and muscles) take care of details
This organization is beneficial because it allows higher levels to focus on complex functions
Why is the motor output guided by sensory input - apart of the three principles of sensorimotor function #2
Sensorimotor system carefully monitors the external world
Able to adjust its own actions (sensory feedback)
- Only ballistic movements are not guided by sensory feedback
What does sensory input help with - motor output #2
Picking things up
Adjusting to unanticipated external forces
Maintaining constant force
How does learning changes the nature and locus of sensorimotor control - one of the three principles of sensorimotor function #3
Initially, actions are under conscious control
With practice, they become integrated sequences of action
They are automatically adjusted without conscious regulation
How does information flow within the general model of the sensorimotor system?
Information flows downwards from the association cortex down to the spinal motor circuits to perform that goal of movements
What is the posterior parietal association cortex?
Provides information on where body parts are in relation to the external world
Recieves input from visual, auditory, and somatosensory systems
Output goes to secondary motor cortex
Stimulation of this area makes subjects experience an intention to perform an action
What is the condition Apraxia?
Inability to perform movements on command
Occurs when posterior parietal association cortex is lesioned
Associated with left hemisphere damage but symptoms are bilateral
What is the condition Contralateral neglect?
Usually produced by very large right parietal lesions
Individuals only attend to right side of body or items in environment
Individuals are capable of unconsciously perceiving objects on the left
What is the dorsolateral prefrontal association cortex?
Recieves projections from posterior parietal cortex
Projects to secondary motor cortex, primary cortex, and frontal eye field
Involved in assessments of external stimuli
May work with posterior parietal cortex in decisions regarding voluntary response initiation
What are the 8 areas of the secondary motor cortex?
Two areas of premotor cortex
Three supplemental motor areas
Three cingulate motor areas
What happens in the secondary motor cortex?
Stimulation produces complex movements (before and during voluntary movements)
Exact role of these areas is unclear
Premotor areas encode spatial relations and program movements
What are mirror neurons?
Fire when an individual makes goal-directed movements
Fire when an individual observes someone else performing goal-directed movement
May be a mechanism for social cognition
Motor cortex in humans may contain mirror neurons (indirectly measured using fMRI)
What is the conventional view of the primary motor cortex?
Somatotopically organized (Penfield)
Body is diffusely represented on the motor homunculus
Body is disproportionately represented
Each areas receives feedback from muscle and joints
Neurons code for preferred direction of movements
What is the current view of the primary motor cortex function?
Body is diffusely represented; regions can overlap
Effects of primary motor cortex lesions
- astereognosia
