My apologies if you receive multiple copies of this message due to
overlaps in mailing lists.
Readers of this list may be interested in the following paper:
Context-dependent selection of visuomotor maps
by Emilio Salinas
BMC Neuroscience 2004, 5:47.
The paper is freely available in its final form (html or pdf) directly
from the publisher:
http://www.biomedcentral.com/1471-2202/5/47
By the way, my experience with this new journal was very positive. It
might be an interesting venue for work of neurobiological relevance. For
information, see http://www.biomedcentral.com/info/authors/
The abstract follows below. Cheers,
Emilio
ABSTRACT
Background: Behavior results from the integration of ongoing sensory
signals and contextual information in various forms, such as past
experience, expectations, current goals, etc. Thus, the response to a
specific stimulus, say the ringing of a doorbell, varies depending on
whether you are at home or in someone else's house. What is the neural
basis of this flexibility? What mechanism is capable of selecting, in a
context-dependent way, an adequate response to a given stimulus? One
possibility is based on a nonlinear neural representation in which
context information regulates the gain of stimulus-evoked responses.
Here I explore the properties of this mechanism.
Results: By means of three hypothetical visuomotor tasks, I study a
class of neural network models in which any one of several possible
stimulus-response maps or rules can be selected according to context.
The underlying mechanism based on gain modulation has three key
features: (1) modulating the sensory responses is equivalent to
switching on or off different subpopulations of neurons, (2) context
does not need to be represented continuously, although this is
advantageous for generalization, and (3) context-dependent selection is
independent of the discriminability of the stimuli. In all cases, the
contextual cues can quickly turn on or off a sensory-motor map,
effectively changing the functional connectivity between inputs and
outputs in the networks.
Conclusions: The modulation of sensory-triggered activity by
proprioceptive signals such as eye or head position is regarded as a
general mechanism for performing coordinate transformations in vision.
The present results generalize this mechanism to situations where the
modulatory quantity and the input-output relationships that it selects
are arbitrary. The model predicts that sensory responses that are
nonlinearly modulated by arbitrary context signals should be found in
behavioral situations that involve choosing or switching between
multiple sensory-motor maps. Because any relevant circumstancial
information can be part of the context, this mechanism may partly
explain the complex and rich behavioral repertoire of higher organisms.
-----------------------------------------
Emilio Salinas
Assistant Professor
Department of Neurobiology and Anatomy
Wake Forest University School of Medicine Winston-Salem NC 27157
Phone: (336) 713-5176
Fax: (336) 716-4534
e-mail: esalinas@wfubmc.edu
www.wfubmc.edu/nba/faculty/salinas
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