Topic 5 - Cortical and Subcortical Structures of the Brain Involved in Sensation and Movement Flashcards
Frontal Lobe
- Higher order cognition
2. Motor function
Occipital Lobe
Processes visual info
Passes info to parietal ans temporal lobes
Temporal Lobe
Receives info from occipital lobe and then identifies objects
Parietal Lobe
Contains primary somatosensory lobe
3D representation of space and our body in 3D space
Overview of Brodman’s areas and order
- From eye to primary and secondary visual cortices
- Somatosensory info to primary and secondsry somatosensory cortices
- Both those ^ to posterior parietal cortex
- Premotor area
- Primary motor cortex
- Pyrammidal tracts
Primary Somatosensory Cortex
Received somatosensory movement related info from dorsal column pathway snd spinocervico tract
Also projects info to other cortical areas as well as SC
Has 4 functional structures
4 Functionsl Structures of the Primary Somatosensory Cortex (S1)
3a - muscle stretch
3b - cutaneous receptors -> touch
1 - rapidly adapting cutaneous receptors (respond when stimulus turns on an off, but not when tbere is sustained stimulus)
2 - deep pressue -> from skin and muscles
Posterior Parietal Cortex (PPC)
Receives somatosensory, visual, and vestibular info
Outputs to other sensory cortices and the premotor correx and cerebellum
3 specific roles of PPC
- Spatial coordinations for action ans attention
- understanding of body in space
- attending to relevant spatial locations and info - Response selection & programming
- helps produce skilled ations with PrM -> ideomotor & ideationsl apraxia - Integration of hand and eye position
- being able to perform efficient correction
- > optic ataxia no longer able to effectively modify movements
Premotor Cortex and 4 functions (PrM)
Inputs/outputs to S1, PPC, SMA, M1 prefrontal association areas and subcortical structures
- Regulates prox and dist mysculature
(Prox-> ventral corticospinal tract, dist-> lateral corticospinal tract) - Response selection and programming via connections with PPC
- setting parameters (force, speed, etc)
- from PPC, what action is most appropriate based on spatial info of objects and limbs
- multiJOINT coordination - Storage of motor plan
- Motor learning (consolidation if motor program)
Supplementary Motor Area (SMA)
Ext of PrM
Inputs / outputs -> S1, PPC, PrM, M1 other subcortical areas and alpha MNs
- Regulates prox and dist musculature
- Response programming
- coordination of multiLIMB movements - Mental practice
Primary Motor Cortex (M1)
Inputs - S1, PPC, SMA, PrM and subcortical sites (cerebellum and basal ganglia)
Outputs
- reciprocal connection w/ inout structures
- pyrammidal neurons of lat and vent corticospinak tracts (alpha and gamma MNs, afferents, efferents)
Fxn
- responsibke for translating movement info to behaviour
Where are directionally tuned cells most often found?
M1 and PrM
3 rules of directionally tuned cells
How they work
- Fire the most for movement in a specific direction
- Fire less for movements deviating from the specific direction
- Are inhibited if movement is in complete opposite direction (ex 90-> 270 or 180->360)
What 3 things do directionslly tuned cells tells us about movement?
- Direction of movement
- Force of movement (⬆️ in firing rate results in increase in force)
- Demonstrate a role in movement planning (bc they begin to ⬆️ rate if firing prior to movement onset -> look a population vector graph)
What do mirror neurons do? (Parietal and PrM areas)
Fire both during the execution and observation of action
- so possibke role in action, learning, and anticipating someone else’s action
3 functions of brain stem centres
Postural responses
Startile elicited and triggered responses (pre programmes responses)
Locomotion -> decerebrate cat
Complex, adaptable, goal direction responses that aren’t entirely voluntary in nature
Sup peduncle
Midbrain - cerebellem
Output from cerebellum
(Ex. Output from cerebellum goes through sup peduncle to get to thalamus)
Mid peduncle
Pons - cerebellum
Input from cortex
Inf peduncle
Medulla - cerebellum
Input from and Output to SC
List 3 functional divisions of cerebellum
- Vestibulocerebellum
- Cerebrocerebellum
- Spinocerebellum
Vestibulocerebellum function
(Vestibular sys cerebellum)
Governs posture and eye movements
The three vestibulo descendinf tracts:
- Vestibulotecto tract
- vestibulooccular reflex, vestibular control of eye movements - Lateral vestibulospinal tract
- postural responses of limbs to vestibulo info - Medial vestibulospinal tract
- reflexive hesd movements to vestibular perturbations
Cerebrocerebellum function
Planning and initiation of movements (can ⬆️ RT if area is damaged)
- coordinating movements with external timing
- timing antagonist (2nd) burst of triphasic EMG
Spinocerebellum function
Planning and execution of movements
- feedback based movements corrections
- timing of antagonist (2nd) burst of triphasic EMG
Cerebellum input & output
Input
- afferent connections from SC via brain stem
- efferent commands from PrM and M1 via brain stem (pons)
Output
- indirect connections to SC via brain stem
- indirect connections to PrM and M1 via thalamus
Basal Ganglia input
Comes in via striatum
Comes in from many cerbreal structures either direct from cortex or indirect from thalamus
Basal Ganglia Output
Back to cortex via the thalamus
-many projections from GPi (internal globus pallidus).
- small pathway from substantia nigra to superior colliculus
- eye movements
Direct vs indirect pathways of BG
Direct - facilitation of goal response
Indirect - inhibition of non-goal response
