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Sun Apr 10 20:43:05 EST 2005

attention is.  You might want to do an author search on Michael Posner
and (David?) Gevins.  These two people seem to have pretty much
opposite opinions on the matter.  Posner does PET scans on humans and
lesion studies in monkeys--he's found a couple of cortical areas that
he believes are related to attention.  Some of his experiments
indicate that attention is an active process that (at least for visual
stimuli) can be localized in space.  In his models shifts in attention
involve three processes--disengaging, moving and re-engaging.  Some of
his monkey experiments indicate that you can actually measure the
speed at which the attentional beacon moves across space as the monkey
shifts its resources from one target to another.

Gevins has reached a completely different set of conclusions in his
experiments on air force fighter pilots.  He does EEG recordings with
up to 144 scalp electrodes on subjects as they perform various tasks.
He feels that attention is not related to any particular place on
cortex, but rather is related to overall pattern of activation.

You'll note that both of these people work pretty much exclusively on
cortex.  Sam is right about the fact that thalamus is often implicated
in attention, since it seems to modulate what gets to what parts of
cortex.  There are some ideas about the role of thalamus in attention,
but other than the reference to Crick, and my next reference to
Sherman, I'm not as familiar with this work.

If you really want to get into some deeper electrophysiology you might
want to check out Murray Sherman who has been trying to elucidate a
mechanism whereby the lateral geniculate nucleus modulates signals
from retinal ganglion cells in order to highlight areas that might be
of behavioual interest.  At the other end (human psychology) you might
want to look into Triessman (sp?).  I know of some of her work in
object perception, but a reputable source (Jenni Groh, a fellow
graduate student) claims that she has done some work on attention as
well.  It seems to me that someone else from NIH gave a talk here
within the past couple of years, and that he spoke about attentional
mechanisms in visual perception.  I'm pretty sure that it was Peter
Schiller, but whoever it was you should be able to track them down in
references by Posner.

You'll probably find work on the area of attention somewhat
dissappointing, because it's one of those things that you can talk
with anyone on the street and they'll know just what you're talking
about, but if you try to pin it down in some way that you can do
experiments with it you'll find that the concept is pretty nebulous.
It is an interesting area to look into, though if you have the
fortitude to do some heavy reading...

>						--Sam
>	<=======================================================>
>	< Samuel R. Peretz			      		>
>	< 126 Anatomy/Chemistry Bldg.		   \ /  	>
>	< University of Pennsylvania		 ------- 	>
>	< Inst. for Neurological Sciences	| 0   0 |	>
>	< (215) 898-8048			|   V   |	>
>	< srp at vision5.anatomy.upenn.edu		|  ===  |	>
>	< aka sam at retina.anatomy.upenn.edu	 -------	>
>	< aka peretz at grad1.cis.upenn.edu			>
>	<=======================================================>

Mickey Rowe   (from the other side of campus--the uglier building
               that's much harder to get lost in)

rowe at pender.ee.upenn.edu

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