Section 5b Flashcards
what is the Basel ganglia and what does it connect to?
it is a collection of nuclei that sit deep in the middle of your brain and it has connections to the thalamus
what are the 5 nuclei of the Basal gangila?
- Caudate nucleus and putamen (together called striatum)
- globus pallidus:
- substantia nigra
- subthalamic nuclei
what are the 4 circuits that involve the Basal ganglia and what do they do?
- motor loop: motor movement
- oculomotor loop: eye movement and frontal field
- prefrontal loop: decision making
- limbic loop: emotions
what is the motor loop connection to?
involves the primary motor and pre motor cortex
what does the prefrontal loop connected to?
dorsolateral prefrontal cortex
the medial pathway has basic postrual control of the…
axial and proximal muscles (core/trunk and closer to centre of body)
what are the 4 major descending brainstem pathways?
- vestibulospinal tract
- reticulospinal tract
- tectospinal tract
- rubrospinal tract
what are the 3 tracts controlled by the medial pathways of the brainstem?
- vestibulospinal
- reticulospinal
- tectospinal
what does the lateral pathways do?
they have muscle control of the more goal directed limbs
what is the tract controlled by the lateral pathway of the brainstem?
- rubrospinal tract
what does the reticulospinal control and what’s its origin in brain?
reticular foramen
- maintain posture and muscle tone in extensor muscles
what does the vestibulospinal control and what’s its origin in brain?
vestibular nuclei
- control posture and orientation of head and body in space
what does the tectospinal control and what’s its origin in brain?
superior colliculus
- head and eye movements
what does the rubospinal control and what’s its origin in brain?
red nucleus
- excitatory influence on the motorneurons on the proximal upper limb flexors
what region controls the initiation of walking and hoq
MesLR (Mesencephalic region of the brain)
- it is connected to the reticular foramen and uses the reticulospinal tract to trigger the CPG
- the cerebellum and the motor cortex also contribute
what does the cerebellum do and what volume of the neurons does it contain?
makes movement smooth, regulate the eye movements and maintains balance, has half the brains neurons while only being 10% of the volume.
what does the cerebellum contain??
contains the
- vestibulocerebellum
- spinocerebullum
- cebrocerebellum
what does the vestibulocerebellum do?
receives visual and somatic sensory from the neck to return it to the vestibular nuclei
what does the spinocerebellum do?
receives somatic sensory from the trunk and limbs, visual and auditory and sends it to the origins of the rubospinal, recticulopsinal and vestibulospinal tract
what does the cerebrocellum do?
receives information from the association cortex
what are the disorders called when cerebellum is damaged and what’s the issue?
dysmetria- abnormal trajectories
dysdiadochokinesis- abnormal rapid movements (clapping)
gait ataxia- slow, “drunk” walk
what are the cortical areas of the brain?
- posterior parietal cortex (most important)
- premotor cortex
- supplementary motor area
- primary motor cortex
what does the posterior parietal cortex (PPC) control?
helps sensory integration and planning and control of motor movements
what evidence supports that the PPC is involved in motor planning?
with of without a memory component in the memory-delay task (or delay task) the PPC is active in during the delay and as a preferred direction is goes towards
example of evidence that PPC is active in planning
different groups of neuron activate before activity like
- set advanced neurons in area 5 activate before a cat steps over the obstacle
what are the sub sections of the PPC?
- parietal eye field
- parietal arm field
- parietal grasp field
- parietal face field
- partial foot field
why is the delay period in the studying of motor planning important
the delay period allows researches to see which neuron receives to the cue, plans the movement and executes the movement
what does the supplementary motor area do?
involved in the motor planning uses internal cues (memory)
what does the premotor cortex do
involved in the motor planning using external cues
- the neurons are active during the planning portion of the memory delay task as well
how is the primary motor cortex involved in motor planning
it is involved in coarse movements because the neruons are organized by behaviour since multiple joints and muscles are involved in simple movements
- direction of movement
- adapting to new conditions
explain population coding (in primary motor cortex)
motor cortex neurons each have a preference in direction. To determine the actual direction of movement, you have to find the vector sum of all the neurons activated. We know this exist because there is more activity when moving in that direction
how does the cerebral cortex modulate the activity of the brainstem and spinal cord
- corticobular fibres control the motor nuclei in brainstem
- corticospinal fibres control the motor neurons that innervate the trunk and limb muscles
show (with supporting evidence) how spinal, brainstem, and cortical centres work together to plan and guide walking
- The MesLR initiates walking causing the CPG in the spinal cord to activate the flexor and extensor circuits
- the sensory feedback from the muscle spindles, GTO and cutaneous receptors alter the signal that the MesLR sends to the CPG to modify walking
What is the supporting evidence that the spinal cord, brainstem and cortical centres work together?
when connection to MesLR in brain is severed from CPG, initiation of walking is not possible however
- when the hindlimbs are oscillated to extension of hip activity in the motorneuron is shown and leg is swug. when flexed, it ceases.
- when hip flexion is manipulated to occur while extension is happening, the extension neurons stop activating to allow flexors
