Organization and Functional Mapping of M1
How is it somatotopically organized?
gross manner
along the precentral gyrus with the lower limbs and feet more dorsal and medially represented and the upper limbs and face positioned lateral and ventrally
The representation of muscles for a given body area are:
multiple, spatially separated and overlapping
fire only when the hand is moved in an extension type of motion but NOT when flexed
pyramidal neurons
What do motor cortex neurons produce
different patterns of activity during different forms and phases of movement
What are the greatest proportion of motor neurons in M1 linked to?
LMNs of hands and face
M1 Somatotopy is more f__________, d____________, and d---------------
fractured
discontinuous
distorted
Other recorded cells demonstrate the ________ pattern of response to an identical task. (firing during flexion, but quiet during extension)
opposite
What are 4 neurons patterns of activity?
Phasic
Tonic
Phasic-ramp
Ramp
Is the gross/general arrangement similar somatotopically to the sensory system?
yes BUT there are MAJOR differences
Tends to be clustered near other groups of class that activate what?
related muscles underlying a given behavior
Pyramidal neurons turn on how many milliseconds BEFORE any muscle activity is performed?
100-150 milliseconds.
Neurons with tonic activation profiles were mostly active during what type of condition?
Static force conditions
The sensory system has a dedicated pathway from a sensory receptor to what cortex?
S1 (this organization allows us to localize somatosensory events on our bodies)
Related to F_________ rather than S___________.
function
structure
M1 neurons fire ________ only on extension not flexion
dependent
Phasic neurons are active during what?
dynamic movement
The activation of M1 is related to what?
force production and how a movement is performed
what are the forms of movement?
dynamic (talking)
static (standing)
The firing of the M1 cells change depending on what?
reaching direction
firing intensity changes in a graded manner to different directions of reaching among its preferred direction
there has to be simultaneous firing of a collection of UMNs
What are the phases of movement?
onset-just starting
peak action-in the middle
offset-ending
Why are sensory and executive inputs directed M1?
to influence goal directed action
connected by association tracts
The complexity of the behavior is the result of ________ activity of a ________ number of neurons responding in __________ ways
combined
large
different