Cortical Control of Movement Lec21 Flashcards
A disproportionate area of the motor cortex is devoted to control of the ___ and ___
hand and fingers
The “indirect pathway” from cortex to spinal cord enables ___ postural adjustments.
feed-forward
The “indirect pathway” from cortex to spinal cord plays an important role in ___
weight shifts
Functionally similar and non-adjacent columns are interconnected by interneurons within the____.
motor cortex.
Cortical areas that plan and initiate motor sequences comprise several ___ distinct but highly interconnected regions.
functionally
Proper motor control requires (3)
timing, position, and physical characteristics of body and muscles
brainstem centers are involved with basic movements and ___ conrol
postural
____ Motor Pathways can be direct or indirect:
Descending
Direct descending motor pathway is from cortex straight to ___
LMNs
Indirect descending motor pathway synapse on
brainstem interneurons
both direct and indirect synapse on the
ventral horn of the spinal cord
the proportion of direct vs. indirect terminations varies between species and changes with ___
age/ development
indirect pathway UMNs –> ___ –> interneurons
anteromedial white matter (rubrospinal and extrapyramidal tracts)
indirect pathway Indirect: brainstem UMNs –> anteromedial white matter (rubrospinal and extrapyramidal tracts) –> interneurons –> ___ muscles
axial and proximal muscles
Long distance interneurons are medial or ventral
medial
Long distance interneurons are medial, go to ___ muscles
proximal
Short distance interneurons are lateral, go to ___ muscles
distal
direct pathway goes to ___ muscles
distal
name 4 indirect pathways
- tectospinal
- reticulospinal
- rubrospinal
- vestibulospinal
tectospinal is involved with__ and __
axial and midline body orientation
rubrospinal is involved with___ controls
distal control, mainly arm flexion
vestibulospinal modifies
reflexes, central pattern generators
which indirect pathways modify reflexes?
vestibulo and reticuno
___ pathway modifies antigravity muscles
reticulospinal
example of direct pathways
Ventral & Lateral Corticospinals (to body), and Corticobulbar (to face)
Most direct corticomotor innervation comes from the___
primary motor cortex (M1)
in the cortex Motor units are controlled by___ or ___ cells
Betz cells or other large, non-Betz pyramidal cells
Lateral premotor cortex is involved in
selection of motor responses based one xternal cues
Medial premotor cortex is involved with
learned sequences, repsonse to intenral cues
supplementary mtoor area and the cingulate motor area are found in the
medial premotor cortex
pre-sma is invovled with
learning sequencies
3 association areas?
1. Pre-SMA: learning sequences
2. Parietal and Temporal cortex - Dorsal pathway - Ventral pathway
3. Prefrontal cortex: decision making, working memory, monitoring outcomes
____ areas are not “cortical motor areas” even though they’re in the cortex.
association
Technically, a “cortical motor area”... (4)
- projects from M1 to motor neurons in the spinal cord, either directly or indirectly
- contains Betz or Betz-like cells that project from layer V;
- can be stimulated to produce movements of discrete muscles or muscle groups;
- displays changes in activity related to parameters of movement.
face is lateral or medial?
lateral
lower face has ___ innervation?
unilateral
upper face has ___ innervation
bilateral
) Individual muscles are represented in ___ cortex locations
multiple (this is convergence)
Individual ____ influence multiple motor neuron pools
neurons
all the LMNs of a motor neuron pool synapse with the same ___
UMN
____ lesion in monkey = difficulty getting food from the tube.
Lateral corticospinal tract
For epilepsy, can map motor cortex via __, then resect “hot” regions or make sub-pial incisions to preserve motor function
direct brain stimulation
Cortical motor neurons can code for (3)
muscle activity, force, or direction.
50% of M1 neurons have “movement-like activity”: neuron fires based on which _____ the hand is moving, regardless of which muscles are being used
direction
3 tasks that must be accomplsihed for proper motor control?
- motor system must produced ACCURATELY TIMED COMMANDS to muscle groups
- motor system must take into account CURRENT POSITION OF BODY and DISTRIBUTION OF MUSCLE MASS
- motor system must take into account/compensate for the PHSYCIAL CHARACTERISTICS OF THE BODY AND MUSCLES
the motor sysytem is ___ organized
heirarchially
lowest levels in motor system heirachry accomplish
most automatic behaviors
highest levels in motor system heirarchy are concerned with
complex planning and selection (at the expense of time!)
motor system is ___ segregated
functionally
____ local circuit neurons control more dextrious mvoement
short distance (lateral)
definition of cortical motor area
has to project to (2)
- motor neurons in the spinal cord
- primary motor cortex
definition of cortical motor area
can be stimulated at low thresholds to poduce movements of ___
discrete muscle or muscle groups
definition of cortical motor area
has to display changes in activity related to
paramters of movement
microstim. studies showed there are mutliple representations of each body part even
within a single motor area
microstim. studies showed that cells with simialr targets are ____
not adjacent to one another (fractured somatopy)
microstim. studies showed columns of functionally related neurons are connected by
horizontal connections
METHOD FOR SPIKE TRIGGERED AVERAGING:1) Record from a single upper motor neuron (#1) and a muscle whose lower motor neuron
(#2) may be influenced by it
2) Average EMG from cell #2’s muscle for brief time after each spike (discharge) of cell #1
3) If cell #1 synapses with cell #2, there will
be a change in EMG (Increase=Excitatory, Decrease=Inhibitory)
SPIKE TRIGGERED AVERAGING allows you to to establish connectivity maps between 1 cortical motor neuron and ___
multiple muscles that it might innervate
if you record from an i___, there is a preferred
direction of movement
ndividual cortical cell
