Class (no 11) 12 Flashcards
Acetocholine important for __
Important Receptors ___
Neurotransmitter important for pereferal motor activity
two important receptors: Nicotenic, Muscrenic
Nicotenic Receptors are
Ionotropic
Muscuringic
binds to receptor, sends G protien to do other things inc. opening a seperate ion chanel
Cell bodies that generate acetroline pathways are in
ponds, midbrain, and baisal forbrain
Lots of acetocoline maintains __
maintains normal cortical excitability
Acetocholine when anestatised
decreased levels
Acetocholine is involved in
selective attention, motavation, reward
Acetocholine is active in
neuromuscular junction - where PNS stimilates activity
motor unit
where neurons (alfa) activates mussles (is both neuron and mussle fiber where it actavates)
motor units are medated by ____ and binds with ___
Acetocholine , Nicotenic receptors (in membrane of skelatal muscle)
opening of ion chanels in motor unit causes
mussle contraction
Reflux circiut
reflex - movments gnerated without cortical imput
alfa motor neurons - innnervate musles - recieve signal from spinal interneuron (in spinal cord)
two pathways where information from brain desends to spinal cord and out
lateral cortical spinal tract
medial tract
lateral cortical spinal tract
- fine motor movement, more distal lymbs
projects contralaterally
medial tract
walking, posture, standing, more procximal parts of lymbs and the trunk
is the extraperamital tracks
project not only contralaterally but also ipsolaterally
cerebellum
from video - “makes movements smooth”
“little brain” 3/4 of neurons of the brain 1/10 of the space - smaller neurons
imputs from all over the brain - visual, proceptrive, vestibular, somatosensory, autory
two hemispheres
prjects ipsolaterally
Functontal dividson of the cerebellum
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
Vestibulocerebellum
balance, eye movement
Spinocerebellum
smooth control of movement, coordination in walking, running
Lateral regions control more distal muscles, more medial regions control more proximal muscles
Cerebrocerebellum
highly skilled movements (requiring sensorimotor learning)
writing and speaking
Basala gangla
group of nucil
though to select what canadate plan of action is vs other alternitives
impotant in initation of action
Dopamine
recepter subtypes (main)
D1 - excitatory
D2 - inhibitory
three differnt pathways in which can act
- Nigrostriatal system
- others involved in reward learning + motivation
• Useful for producing actions that have rewarding consequences!
doubble inhibiton circult
lowers baceline level of activity
makes certine signal stand out (by disinhibiting it, or not inhibiting it)
Nigrostriatal system
housed in substantra nigra - wheere cell bodies for DA activirt is highjlighted/housed
primartly in control of movement
Basal gangla - orgnaization
organixation of different patheays
green- exitory
red - inhibitory
How basal gangla influence cortical activity
two wats
direct root
indirect root
direct root
Does:
activated by:
Pathway:
Cortical excitation:
facilate movement - alows for initation of movment
activated by D1 receptors
DOrsal striatum is activated - inhibits internal segment of globus palatas
inhibatory done by gabergernic
net level of higher cortical excitation
substantia nigra sends __
can send both excityory and inhibtory
globus palatas internal segment normaly
(GPi) inhibits the thalamus
Thalamus connections to the cortex are
excitatory
indirect root
does:
activated by:
pathway:
cortical excitation:
in generally, supressing unwanted movments
D2 receptors
Normaly dorsal straitum (actavation) is inhibiting external segment of the GP
and the GPe normaly inhibits the subthalamic nuclis (STN)
subthalmic nucleis activates GPi (which inhibits the thalamus)
net level of lower cortixal excitation
Supplementary motor cortex
areas:
does:
supplementary motor area, supplementary eye field, presupplementary motor area
help code motor plan
motor plan
representation of intended movement
general - what is goal of movement want to do
specific - muscular control needed
Information contained in motor plan
- Which effectors to use
- Which order to use them
- Direction and force of individual effectors
- Timing between movements
- Commands for motor neurons
What are effectors
muscles, areas of body that move
most activity in SMA
is leading up to action
neuron in SMA sensitive to
order that things are done (Push pull vs pull push)
Pre SMA order
(order) does not matter
increased activity prior to third movement
Mirror Neurons
Not only to doing action but to someone else doing that action.
can be specific or broad
- coding for intent of action (can fire even if not see)
Anterior cingulate cortex
where:
implicated in:
(ACC) above CC
implicated in motor activity, attention, and emotion
motor - more activity in control and planning of new (untrained) movements
selecting for movement among compeeting alternatives (clasic word vs color)
Bimodal neurons in parietal cortex
proprioceptive, kinesthetic, somatosensory and visual info
- modulate receptive fields
damage to parietal regions
(dorso-dorsal stream) causes optic ataxia
optic ataxia
imparments to reach and grasp baised on visual information
Primary Motor Cortex
Organization:
Mapping:
M1
Parts of body with fine motor control are bigger
Organized around specific body area for specific region
distortion of size of region compared to size on body
Mapping is upside down, more dorsal regions (lower parts of body) more ventral (face)
Corticomotor neurons synapse directly onto
alpha motor neurons (instead of onto spinal interneurons)
cortical motor neurons more responsive to
fine control, precision (pinch, small changes) (vs power gripping)
each motor neuron cell has ____ (movement preferences)
different preferences for movement
direction vector
combine activity of motor neurons: summation of direction moving towards
Direction: cell’s preferred direction
Length: firing rate of cell at a given moment
population vector
summation of direction vector
D1 is
excitatory
D2 is
inhibitory
basal ganglia uses ___ and acts on ___
uses double inhibiton circuit
act on dopameane
alfa motor neurons recceive preferfy imput from
muscle spindles
Distance between represntaions in M1 is closely related to
how often (two fingers) are used togehter
CM neurons are preferntal active durring ___ comapired to ___
Pinch, power grip
SCn to the striatum is known as
the dopamine pathway
GPi and SNr have __ baseline firing rates producing
high, strong tonic inhibition of the motor system by the inhibitory projection to the thalamus and superior coliculi
basal gnaglia can act as a __ and play a critical role in the
gaitkeeper of cortical activity, initation of actions
As a specitic motor plan gains strength the inhibitory signaling __
is decresed for selective neurons.
