Ear Lobe

Terry Smith terrys at gastro.apana.org.au
Sun Aug 21 12:35:15 EST 1994


> From: footc at aol.com (Foot C)
> Date: 13 Aug 1994 09:09:04 -0400

> The pinna of the ear however is not involved in locomotion
> or survival. Auricular therapy sees the pinna of the ear as
> somatotopic but does the sensorimotor cortex really contain
> much representation of the lobe? All the models I've seen
> has little tiny ears.

The fact that you can feel sensation from there indicates that
it does. As an anecdotal example, one of the most effective ways
of waking a deep sleeper is to pinch the fleshy lower lobe of
the ear. I have used it often when flat-mates have needed a
little pursuasion to stagger to work after deep philosophical
evenings.

Have a look at models for other species, such as apes or rats.
One of the specific distinctions of the human maps is the area
dedicated to the thumb and hand - about a third of the total.
This varies with other species, depending on which somatic areas
are needed for locomotion ect. I would imagine an elephants
trunk would be well represented, whereas a horses feet wouldn't
be mapped to the same extent as a human hand.

Arguments as to whether this is an innate or developed map in
any individual are best left till your next bottle of
Glenfiddich.

I'm sure your aware that there is a distinction between the
sensory and motor cortex. One ethical way you could assess the
amount of sensory cortex allocated would be by use of the `Two
Point Tactile Stimulation' test. [HIV awareness warning]. The
results from this appear to correlate very highly with cortical
allocation. I doubt, given the amount of fine motor control
possible with this area, that very much motor cortex is
allocated to it.

Terry Smith
--
Usenet: terrys at gastro.apana.org.au
Fidonet: 3:800/846.23



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