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Human and monkey perceptual decisions in changing conditions| old_uid | 6541 |
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| title | Human and monkey perceptual decisions in changing conditions |
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| start_date | 2009/03/19 |
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| schedule | 16h |
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| online | no |
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| summary | Over the past two decades significant progresses have been made toward
understanding the neural basis of primate decision-making. Although this
high-order cognitive process can be extremely complex, most of
decision-making studies and models have largely focused on perceptual,
binary choices. It has been suggested from these studies that simple
decisions are made through a process of “bounded integration”, in which
neurons integrate sensory evidence until a threshold is reached.
Especially, cortical and sub-cortical areas devoted to saccade planning
and execution (LIP, FEF, SC) seem to integer the momentary sensory
evidence during oculomotor decisions. However, nearly all of the results
supporting this theory have been obtained in tasks where sensory
evidence was /constant/ during the course of each trial. In such
specific situation, behavioral and neural data are also compatible with
a model in which there is no integration of sensory evidence, but
instead a multiplication of current evidence by a growing “urgency” signal.
In a recent study, Cisek et al. (/submitted/) have presented human
subjects with a task (“tokens task”) in which /evidence changed over
time/. Results are more consistent with the “urgency-gating” model than
with “integrator” ones. Moreover, preliminary data on humans tend to
show that such mechanism is not task-specific, as we found similar
results in another task (“dots task”) in which stimuli providing
subject’s sensory evidence were sensitively different. Finally, in order
to probe the neural basis of decisions in /changing conditions/, we
trained a monkey to perform the “tokens task”. Our first hypothesis is
that cortical areas devoted to planning and execution of arm movements
(e.g. PMd) are recruited when a decision has to be made with the arm.
Then, according to our behavioral data, we make the prediction that the
product of the momentary information and a growing signal related to
elapsed time (“urgency-gating model”) is used and compared to a
threshold to form decisions. |
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| oncancel | Séance initialement prévue le 11 décembre 2008 |
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| responsibles | Farnè, Béranger, Soulier |
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