Motor Areas Flashcards
Cortical areas associated with voluntary movement
-Motor cortex (M1)
-pre motor cortex (PMC)
-supplementary motor area
-association cortex:posterior parietal cortex
Prefrontal cortex
-somatosensory cortex
-cerebellum and basal ganglia
*ALL of these areas go through M1 (directly or indirectly) before traveling to the spinal cord
Voluntary movement
Organized around performance of purposeful, unique tasks (unlike reflexes which are distinct and repeatable)
Effectiveness is improved with experience repetition and learning
-internally initiated…not in response to stimuli
Pre motor cortex
- mainly projects to M1, but has some direct connections with hand muscles
- involved in the selection of appropriate motor plans (primarily using sensory feedback)
- cell bodies signal the preparation of movement
- signal the sensory aspects of motor acts, mirror actions..respond to an action regardless of how it was detected
- signal incorrect actions (prepare a new correct movement)
- Sensistive to behavioural context
Damage to promotor cortex
-damage may cause difficulty performing movements in response to verbal or visual commands
Supplementary motor area
-involved in programming complex movements based on remembered sequences of movements I.e throwing a frisbee
-cell bodies within the SMA …
Reapond to sequences of movements
-respond to ___ of sequences
-are involved in creating the appropriate dynamic, complex motor output
Association cortex
-receives input from multiple sensory sources then projects to the PMC and and SMA.
-necessary to assure ADAPTIVE MOVEMENTS
Consists of two major areas
1)posterior parietal cortex:involved in integrating sensory modalitites for motor planning
2)prefrontal cortex:working memory, location objects In space to guide movements
Damage to association cortex
-deficits in the in the memory and perception of spatial relationships
Apraxia:difficulty performing movements out of context, but can perform the same movement naturally without thinking about it I.ebrushing your teeth
Contralateral neglect-inability to respond to stimuli on one side of the body I.e: eat all food on one side of plate
Primary motor cortex M1
Involved in the execution of voluntary movements
-controls individual movements, which require the activity of multiple muscle groups.
-cell bodies within M1 fire directly BEFORE onset of muscle movement
-code for the force, speed and direction of movement
DAMAGE to motor cortex motor control deficits, impairment of moving body parts independent of each other..reduced movement speed accuracy and force…but much less than might expect.
Does not eliminate voluntary movement all together , a lot of parra
El pathways
How motor areas work together to generate movement
1) association cortices (AC) and S1 receive sensory input via thalamus ,cerebellum and basal ganglia
2) info from AC is sent to the SMA and PMC to organize complicated events
3) then finally sent to M1 which sends signal down spinal cord to the alpha motor neuron to cause contraction
Plasticity of the cortex
-plasticity is the ability of a synapse to strengthen or weaken over time in response to increased or decreased activity
-short term effects:
Long term potentiation: increased neurotransmitter release, more receptors
Long term depression :less receptors, less NT release
*actual long term effects..new synapses between neurons I.e /amputees
Trans cranial magnetic stimulation TMS
- electrical current passed through coil generate electrical field
- when placed against the skull, stimulate neurons within the cortex
- generates AP in axons
- stimulate motor cortex to generate a muscle twitch
Different forms of TMS
Single/paired pulse :elicit single muscle twitch, used to map the cortex and look at excitability
Repetitive:high or low frequency to cause LTD OR LTP
