Topic 4: Action Flashcards
Somatic action
skeletal muscles (like moving a limb)
Autonomic action
smooth muscles, cardiac muscles, endocrine glands, and exocrine glands
Action in CNS
update memory, switch tasks, etc.
The inverse problem
determining what actions to take in order to achieve goals
the supplementary motor cortex is more ____ than the premotor cortex (lateral/medial)
medial
the primary motor cortex is more ____ to the supplementary motor cortex (rostral/dorsal)
dorsal
Inverse vs. Forward models
Inverse: current position and desired position –> creating motor commands
Forward: current position and motor comments –> predicted position (evaluating motor plans)
Efference copy
Internal copy of a motor command
Feedforward control
motor command sent to muscle; faster but less accurate
feedback control
motor command sent to muscle; actual state compared to desired state; adjustments based on errors; slower, but more accurate
would a feedforward controller use a forward model or an inverse model
inverse
How is the premotor cortex involved in motor planning?
selecting goals and planning actions at a conceptual level, particularly when plans are driven by external stimuli; happens before voluntary movement
Monkey alternative actions study (what happened, what did it show?)
monkey is cued by two spatial cues of the two possible targets, they cues are removed, monkey is cued with actual target and prepares single action, go signal and monkey initiates action
premotor neurons for the arm were active and planning the movement before it happened
mirror neurons
a neuron in the frontal or parietal cortex that shows similar electrophysiological responses to actions executed by oneself or to observation of the same actions being executed by another (conceptual level)
Supplementary motor cortex (SMA)
selecting goals and planning actions at a conceptual level (especially with sequences)
- fire in anticipation of a particular sequence
what happens to a monkey in a motor task when they have they supplementary motor cortex inhibited?
no longer perform well learned movements and must rely on external cues to tell them which movement should be performed
when happens to those with lesions in the premotor cortex?
disrupted visually guided movements, but their ability to commit learned tasks is fine
T/F
The motor cortex represents movements of specific muscle actions, not directional movements of body parts
False
- different neurons have different directional sensitivities
Tuning Curve
shows the response rate of a neuron based on the direction of movement; can been determined through population vectors
Population vectors
adding up all vectors for a neuron from its preferred direction and the length (firing rate)
- shows the actual movement direction
- direction of this predict the direction of a forthcoming movement
Define all four Intraparital sulcus spaces (LIP, VIP, MIP, and AIP)
Lateral (LIP): space for eye movements
Ventral (VIP): space for facial movements
Medial (MIP): space for arm
Anterior (AIP): space for hand movements
What do the IP areas do?
important role in guiding movements to correct location, orientation, and configuration
What are three main things the basal ganglia helps with in motor action?
- select, initiate, and inhibit movements through cortico-basal ganglia-thalamocortical loops
- critical to dopamine-based reinforcement learning
- participate in motor control, cognitive control, and emotional control
What is the difference between the direct and indirect pathway of the basal ganglia
the direct pathway goes right from the striatum to the GPi/SNr through a single inhibition; whereas the indirect pathway goes from the striatum, to an inhibition of the GPe, inhibition of the subthalamic nucleus, and thn an activation of the GPi and SNr
baseline activation in basal ganglia
inhibiting the thalamus
action initiation in basal ganglia
direct pathway, aids in the selection and initiation of action
action inhibition in basal ganglia
indirect pathway; closing gate inhibiting additional actions; more steps in indirect make it slower
reinforcement learning in basal ganglia
unexpected rewards generate dopamine which excites the direct pathway, and inhibits the indirect, allows modification of behaviour based on reward
what happens to coordination when you have a lesion in the cerebellum
can’t make accurate movements
what two types of neurons are most prominent in the cerebellum?
granule cells (50 billion.. 75% of neurons in brain) and purkinji cells (~200 000 inputs per cell)
Does the cerebellum use a forward or inverse model? Feedback or feedforward?
forward, to predict results of motor commands using the differences between actual results and predicted results; feedback
what do axons from the primary motor cortex synapse on?
lower motor neurons and local circuit neurons (interneurons)
Central pattern generators
local neurons in the spinal cord can control complex movements and respond to environmental changes even without higher-level input
lower motor neurons synapse on…
muscle fibres
what happens at a lower motor neuron-muscle fibre synapses?
the release of neurotransmitters cause the muscle fibres to contract, which is then detected by the spindles so they can be sent back to the spinal cord through the dorsal root ganglia
areas that are ____ (more/less) specific with finer motor control needs have a smaller number of muscles that it sends its signals to
more
brain machine interfaces
an array of microelectrodes is attached to the primary motor cortex that controls arm movement, and a calibration between the robot arm and the neurons allow for the person to control the robot by thinking
