Spinal Cord and Processing Two Flashcards
What brain regions are involved in processing somatosensory information?
A number of brain regions are involved in recieving, relaying and processing somatosensory input
What is the role of the thalamus in somatosensory processing?
Its VPN (ventroposterior nucleus) receives input from second order neurons in the posterior column medial lamincus pathway and the spinothalamic tracts. It then projects (relays) up to the primary somatosensory area.
The sensory pathways innervate different parts of the thalamus depending on what information they are carrying. (it is mapped very precisely)
What is the role of the somatosensory cortex one (primary)?
Receives inputs from the thalamus.
How is the somatosensory cortex one divided?
Into broadmanns area
3a, 3b, 1 , 2
- Based on its cytoarchitecture and function
- Somatotopically organized
What does the broadmanns areas implicate?
- Different areas receive different information
- The cortical layers project between one another.
- Important for the co-ordination of movement
what cortical layer does the thalamus project to?
It projects to cortical layer four (4)
Where do fibers of the VPN in the thalamus project to?
Mostly to the 3B of S1
3B projects onto S2
Whats the role of S2?
Somatosensory information intergration
Where does S2 project to?
S1 (regulation)
Association Cortex
Motor Cortex
Amygdala and hippocampus (Tactile learning)
What is the role of the somatosensory association cortex?
- Higher order processing
- Input from visual cortex
- Projects to motor cortices (voluntary movement)
- Learning complex associations
What is somatosensory plasticity?
Changes in cortical representation occur following injury or due to experience (training)
How fast can somatosensory plasticity occur?
- Can be instantaneous, transient
What causes somatosensory plasticity to occur?
- Due to training or change in behavior from normal. Cortical map will return to normal if task not continued.
- Over time stable enlargement of the cortical representation can occur (structural plasticity)
What anatomical feature allows structural plasticity to occur?
Overlapping projection zones allow for changes in fields. (i.e growth in a tonotopic zone)
- Can occur due to injury or training
- With injury, neural inhibition is lost, can be rapid
- “Use dependent” synaptic strengthening takes days or weeks
What does loss of input (i.e nerve death) lead to?
permanent re-organization of the cerebral cortex
What may cortical changes (caused by loss of input) also result in?
Subcortical modification
- Branching of axons from one zone to another, i.e when they fire you can cause phantom pain