Upper Motor Neurons Flashcards
where do upper motor neurons in the brain stem project to
the medial ventral horn lower motor neurons
where do upper motor neurons in the cerebral cortex project to
lower motor neurons in the lateral ventral horn
which parts of the cerebral cortex are associated with planning of voluntary movement
primary motor area, premotor cortex, and supplementary motor area
corticobulbar tract
controls facial movement
corticospinal tract
-controls upper extremities, trunk, and lower extremities
-supply most of the inputs to the cerebellum
lateral corticospinal tract
pathway from the cortex to the spinal cord which crosses the midline. lateral corticospinal tract demonstrates contralateral control of lower motor neurons
corticobulbar tract
ventral corticospinal tract
ipsilateral controls of lower motor neurons, the upper motor neurons do not cross the midline of the spinal cord
-include areas controlling the trunk, hips, shoulders, and elbows
-direct output from primary motor cortex
where do layer 5 pyrimidal neurons extend their upper motor neuron axons to
through the corticospinal and corticobulbar tracts
what causes AMPA receptors to close
-AMPA receptors undergo rapid desensitization due to the change in angle of the blocker to the binding site/pore
-AMPA receptors should be open long enough to allow for enough magnesium to be repulsed and for NMDA receptors to open
how do you determine the cortical neurons to record from when making an upper motor neuron algorithm
-take note of the brain region which activates when a certain motor task is occurring
-for each iteration align neural activity (eeg spikes) with motor movement (electromyograph)
-average the records
explain the monkey joystick experiment algorithm
-part 1: the monkey was placed in an apparatus where it had control of a joystick which moved in 8 different directions. the monkey was conditioned to move the joystick in the direction a green light indicated via reward learning.
-part 2:
-raster plots were constructed to record the firing of motor neurons during movement in each direction. their max firing rate across the trials in each direction for each neuron was recorded.
-each motor neuron was used to construct a tuning curve. the tuning curve shows the different avg max firing rates of a motor neuron when you are moving in each direction. the highest frequency firing rate of the neuron (peak of the tuning curve) marked their preferred direction
-part 3:
-take note of the preferred direction of each neuron (where it fires most/peak of tuning curve). express the firing of each neuron in a particular direction as a vector with the magnitude of firing frequency and its preferred direction.
-determine the magnitude and direction for all neurons when moving in a particular direction
-plot all of the neuronal vectors together and use vector summation. this should give you a prediction of where to monkey moves the joystick
-part 4: repeat for all directions and you should be able to predict the movement of the monkey’s arm before it happens
mirror neurons
-located in the premotor cortex and sensory cortex
-fire when seeing another being perform a movement it is familiar with
-also fire prior to its own movement
-also fires before associated sounds and such that it has linked with a movement
-motor neurons represent the meaning of an action/interpreting the intent of an action
-mimicry/empathy
what is the correlation between mirror neuron activation and autism spectrum disorder
negative correlation between neuron activation and asd symptom presentation
what are the three types of plasticity
synaptic (strengthening or weakening of synapses), anatomical (change in anatomical connections between neurons), and behavioral (learning things)
