Neurophysiology homework question- sensory rewiring

[shanwilmo]

1. Sensory primary cortices simply receive action potentials and then create a perception (based on the brain area) for person to experience. If a sensory neuron for touch located in the elbow was somehow rewired to a person's primary olfactory cortex, then every time the person's elbow was touched, they would perceive some smell.


With that in mind...

John has been in a freak accident. While John's dorsal column-medial lemniscal pathway is still intact, his primary somatosensory cortex was destroyed in the accident, resulting in his inability to perceive touch stimuli from his skin. The accident also destroyed all of his cochlea and auditory nerves, leaving him unable to sense auditory information . However, is auditory cortex is still functional.

Physicians think they can rewire John's touch neurons to his primary auditory cortex (both of which are still functional) so that John is able to detect and consciously respond to touch stimuli in a meaningful way. They have asked you to brainstorm a way for John to be able to detect touch stimuli using the perception of audition created by his primary auditory cortex. Without discussing the logistics of the wiring mechanism and pathways, describe how this could be done, focusing on what John will perceive in order to decode all aspects of the incoming touch information (e.g. magnitude of the touch and location on the body).

Homework Equations

3. I was thinking that if the Dr. were to rewire John, they should do it by tapping into his the part of his auditory cortex that perceives musical notes, such as piano notes. I would try to make it so that John would be able to percieve by hearing where and how he was touched, based on the note and volume of a musical note.

For example, to solve the problem of where he is being touched, I would have it so that the lowest octave would be at his feet (the lowest note being at his big toe and notes increased in height as you made your way toward the ankle) and the octaves increase as you go toward the head. ***I don't know if i should have it be going toward the head or if the peripheral should be the lowest and highest be the most central***

Then a sharp note would be taken as pain, a flat would be taken as an itch, and burning would be perceived as a two notes played quickly.

The magnitude of the touch, pian, itch, or burning, would be perceived as how "loud" he perceives the note is (since he can't actually hear). For example, a very slight touch on his forehead would be percived as a very quite high note. Where as a blow to the head with a baseball bat (if it did not kill him) would be taken as an Extremely sharp, extremely loud high note at the highest octave.

This is my start. Please let me know what you think and how I could improve my answer! I really appreciate the help.

 

[atyy]

OMG! This is a homework problem? Very impressive what kids learn nowadays.

One possibility you haven't used is that they should just rewire, and let the brain learn the new associations.

You may like to know about animal experiments where they rewired visual input to the auditory cortex http://www.ncbi.nlm.nih.gov/pubmed/10786793.

And related work in people http://en.wikipedia.org/wiki/Paul_Bach-y-Rita. These sensory substitution techniques are technically not neural rewiring, but they are conceptually rewiring at the periphery.

I should note that the homework question states "If a sensory neuron for touch located in the elbow was somehow rewired to a person's primary olfactory cortex, then every time the person's elbow was touched, they would perceive some smell.", which appears contradictory to von Melchner et al's statement "'rewired' ferrets respond as though they perceive the stimuli to be visual rather than auditory". The word "perceive" may be carrying different meanings here. Perhaps better language would be "the animal/patient" is able to receive visual/somatosensory information through its/his auditory cortex, and the information is sufficiently fine that it/he can respond with appropriate behaviour to an appropriate visual/somatosensory stimulus.