Biology Reference
In-Depth Information
Chapter 12
D
OPAMINE
-D
EPENDENT
S
YNAPTIC
P
LASTICITY IN THE
C
ORTICO
-B
ASAL
G
ANGLIA
-T
HALAMOCORTICAL
L
OOPS
AS
M
ECHANISM OF
V
ISUAL
A
TTENTION
Isabella Silkis
*
Institute of Higher Nervous Activity and Neurophysiology, Moscow, Russia
A
BSTRACT
A hypothesis is advanced that dopamine-dependent synaptic plasticity (LTP, LTD)
and subsequent activity reorganization in the cortico-basal ganglia-thalamocortical loops
underlies attentional selection and processing of a visual stimulus. Both effects are the
result of opposite modulatory action of dopamine on strong and weak cortico-striatal
inputs that synergistically leads to disinhibition and inhibition via the basal ganglia of
thalamic cells projected to those neocortical neurons, in which initial visual activation
was strong and weak, respectively. Thus, the output basal ganglia projections to the
thalamus could play a role of “attentional filter” that amplifies cortical responses to
attended stimulus, and suppresses reactions to ignored stimuli. A proposed model based
on cortico-striatal synaptic plasticity allows explanation of some experimentally revealed
effects of which mechanisms were unclear from points of view of commonly accepted
models that are based on feedback connections from higher to lower cortical areas and to
the thalamus. We assume that proposed necessity of sensory activation of dopaminergic
cells for switching the attentional part of processing and known latency of sensory
activation of dopaminergic cells (which is about 100 ms) explain the experimentally-
* I.G. Silkis PhD, Doctor of Biological Sciences, Lab. Neurophysiology of Learning, Institute of Higher Nervous
Activity and Neurophysiology, Russian Academy of Sciences, 117485, 5a Butlerova str., Moscow, Russia Tel. +7
(495) 7893852 Fax. +7 (495) 3388500
Email: isa-silkis@mail.ru
