movement cortex Flashcards
What is motor control?
the ability to regulate or direct the mechanisms essential to movement
What is motor planning?
preliminary organization prior to movement
What is motor programming?
specifications that allow movement to progress
What are the motor areas in the frontal lobe?
Primary Motor- precentral gyrus
Supplementary Motor- most superior and medial aspects of the superior frontal gyrus
Lateral Premotor- rostral to primary motor cortex
What are the motor areas in the parietal lobe?
posterior parietal area
What are limbic areas associated with motor cortical areas?
Anterior and posterior cingulate cortex
What Brodmann area is the precentral gyrus(primary motor cortex?
4
What is the somatotopic organization of the primary motor cortex?
homunculus with the LE dorsomedial, UE and face ventrolateral
What is a fractured somatotopy?
what the primary motor cortex presents with. it is overlapping regions and scattered distribution of motor neurons which innervate specific muscles
Fractured homunculus
cortical motor (CM) neurons to specific muscles represented in several areas
Primary motor cortex is what level in the motor hierarchy?
lowest level of motor cortical hierarchy
What are the two debates about the primary motor cortex role?
- encodes specific muscle kinetic features (such as amount of force for specific movement)
- kinematic features such as speed, direction and spatial path
Where is the supplementary motor cortex?
along the superior and medial aspect of the superior frontal gyrus
What is the somatotopic representation on the supplementary motor cortex?
Face, UE, and LE are arranged in a rostral-caudal orientation
What is produced with stimulation of the supplementary motor cortex?
movements but in a complex synergy pattern
When is the supplementary motor cortex active?
up to 120 ms before the movement occurs! (suggesting that it is a site for motor planning)
What is the motor planning aspect of the SMA strengthened by?
projections to the basal nuclei and cerebellum which help in organization of he movement performed by the primary motor cortex
What S/S are produced with damage to the supplementary motor cortex?
problem in bimanual tasks, motor memory and motor learning
Where is the premotor cortex located?
just rostral to the primary motor cortex with a rough somatotopic organization that parallels the primary
Just like the supplementary motor area, the premotor area is involved in what?
synergy patterns when stimulated
Where are kinematic features of targeting movements?
actually there is a debate on this whether it is in the premotor cortex or the primary motor cortex
What is the role of the posterior parietal cortex?
it is critical for providing spatial information for goal-directed movement
What other spatial information does the posterior parietal cortex have?
spatial relationships of the environment and how these impact the movement as it takes place
What information does the posterior parietal cortex give about goal directed movement?
- orientation of the body toward the goal directed object
- determination of the relative shapes and sizes and orientation of objects within the environment
What is the cingulate motor area?
limbic cortex (anterior cingulate gyrus)
What does the cingulate motor area contribute with the parietal lobe to?
about 1/3 of the pyramidal tract neurons
What is similar about the cingulate motor cortex and the supplementary motor cortex?
somatotopic map of face to feet in a rostral-caudal orientation
What type of projections are in the cingulate motor cortex?
cingulospinal projections
Where do cingulospinal projections terminate?
in the intermediate gray, influencing LMNs via interneurons
Where does the limbic cortex receive input from?
amygdala and non motor areas of the cingulate gyrus
What is the function of the anterior cingulate gyrus?
provides motivational and reward (goal of performance) information
Where does input to the primary motor cortex come from?(4)
- primary somatosensory areas analogous to the regions of the primary motor cortex
- premotor cortex, SMA, CMA
- dorsolateral prefrontal cortex (DLPFC)(which also goes to SMA and CMA)
- posterior parietal input
What is the function of the dorsolateral prefrontal cortex?
- short term memory for action related sensory information
- preparatory motor set
- inhibition of motor response to distracting stimuli
What is the basal nuclei loop?
- supplementary motor cortex to the striatum
- direct and indirect pathways within basal nuclei and the incorporation of the substantia nigra
- GPi/SNr to VL/VA thalamus then onto primary motor cortex
What does the cerebellar loop involve?
primary and premotor cortex to the pontine and inferior olivary nuclei
What do the pontocerebellar and olivocerebellar fibers of the cerebellar loop have input to?
deep cerebellar nuclei and the cortex
Where do the deep cerebellar nuclei of the cerebellar loop have output to?
VL thalamus and back to the primary motor cortex
What is the PAS? What does it mean?
perceptual action system means that purposeful movement does not occur in isolation from the sensory perceptual experience of the environment (requires input from the environment to correctly execute motor action)
What is Haptic sensing? examples
generation of sensory input from deliberate motor action
exploration of an object by the hand
integration of cutaneuous and proprioceptive information
What does haptic sensing require?
working memory which is provided by action of the dorsolateral prefrontal cortex and the posterior parietal cortex
What are visual saccades?
ballistic voluntary conjugate eye movements used to capture a visual image onto the fovea of the retina
when are visual saccades used?
in reading and visual scanning
Where do the motor programs for saccades reside?
in the RF of midbrain and pons (central pattern generator for conjugate eye movement)
What is the central pattern generator for conjugate eye movement controlled by?
the superior colliculus
What does the superior colliculus coordinate?
movements of the eyes via tectobulbar projections (to RF central pattern generator) and head via the tectospinal tract (to c spine)
Where is the frontal eye field located?
in the middle frontal gyrus rostral to the premotor cortex
What is the function of the frontal eye field?
generates contralateral horizontal conjugate eye movement
Where are projections from the frontal eye fields?
superior colliculus and then to RF
Where is there a supplementary eye field located?
in the supplementary motor area
Where does the supplementary eye field project?
to the brainstem and the frontal eye fields
Where is the parietal eye field located?
in the parietal lobe just inferior lateral to the posterior parietal area
where does the parietal eye field project?
to the brainstem and to the frontal eye field
What are the roles of the supplementary eye field and the parietal eye field?
unclear but maybe an organizing function of the supplementary eye fields and spatial coordination of parietal eye fields
What is the first step involved in the performance of an instructed motion?
activation of auditory cortex
second step in performance of an instructed motion?
interpretation of command through Wernicke’s
third step in performance of an instructed motion?
activation of the parietal eye fields and posterior parietal cortex for placing this command within the movement space (spatial environment and coordination of eye movement to that site of placement_
What is the 4th step in the performance of an instructed motion? (after spatial awareness)
organization of motion by premotor cortex and supplementary motor cortex
what is involved in organization of movement?
basal nuclei and cerebellum
What is the 5th step of performance of an instructed motion?
primary motor cortex for command of spinal motor neurons to perform the movement
What is needed for proprioceptive feedback to cerebellum?
cerebellar efferent copy
