Physiology 2130 Lecture Notes - Lecture 17: Central Sulcus, Visual Cortex, Somatosensory System
1 May 2018
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Lecture 017: Neurophysiology V
● Somatosensory system 1
Last lecture
● Peripheral receptors deconstruct environmental energy
This lecture
● How somatosensory cortex processes and reconstructs (decodes)
● Need to reconstruct to turn the population of spikes into a representation of the an object
in the hand or the texture of a surface
Reconstruction happens in
● Brain stem, cortex
Somatosensory Cortex
● Behind the central sulcus
● Critical for conscious awareness
Somatotopic organization
● Map of the body laid out in a semi-orderly fashion on the somatosensory cortex
○ Feet: medial, head: lateral
○Somatosensory Map
■ Different creatures have different representations/mapping
● Related to their use of the somatic senses
● Ex. rat/mouse have much larger regions devoted to the whisker
(barrel cortex)
○ Is a distorted map
■ Representation of the body parts are not correlated to physical size
■ By the sensitive of the region (more receptors, more processing needed,
thus greater representation)
● How do we know?
○ Recording, lesions, stimulations
● Why is it important?
○ Source of seizures
■ Idea of where the dysfunctional neurons are based on what is affected
■ Initial diagnoses
○ Location of tumor
■ Based on behaviour responses of the patient
Plasticity
● Somatotopic organization is present at birth
○ Genetic bases
● Size of regions is modified with use
○ Braille (larger representations of the finger regions, visual cortex also start to
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Document Summary
How somatosensory cortex processes and reconstructs (decodes) Need to reconstruct to turn the population of spikes into a representation of the an object in the hand or the texture of a surface. Map of the body laid out in a semi-orderly fashion on the somatosensory cortex. Related to their use of the somatic senses. Ex. rat/mouse have much larger regions devoted to the whisker. Representation of the body parts are not correlated to physical size. By the sensitive of the region (more receptors, more processing needed, thus greater representation) Idea of where the dysfunctional neurons are based on what is affected. Based on behaviour responses of the patient. Size of regions is modified with use. Braille (larger representations of the finger regions, visual cortex also start to respond to tactile information) , music, juggling. Processing power can be redirected if unused for what is originally used for. Take over by flanking regions (what is closer)
