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Research
Developmental
Plasticity of the Retinocollicular Projection
Using the retinocollicular system, we create a mismatch between the retina
and the superior colliculus (SC) at birth by
removing part of the SC. The retina then makes a complete but compressed
visual map in the SC fragment. Despite the smaller target, the properties
of the SC neurons remain unchanged. This remarkable conservation of
function suggests to us that the mapping of the retina onto the SC and the
functional development of individual target cells are controlled in
concert. We are currently investigating the molecular mechanisms underlying
this process, which is likely to be of general importance in brain
development and plasticity. This work has been funded by the NIH.
Cross-Modal
Plasticity of the Retinogeniculocortical System
Using the retinogeniculocortical system, we are
investigating the consequences of changing the modality of sensory inputs
to central brain structures. The retina can be induced to innervate the
central auditory system early in development. This allows us to define the
role of sensory input modality in the development and evolution of specific
cortical circuitry. Earlier work showed that rerouting the retina to the
auditory system results in an orderly map of visual space in the auditory
cortex, and that visual information can be processed by auditory cortex in
much the same way as in visual cortex. Our working hypothesis is that the
sensory inputs can direct the formation of cortical circuitry. We have now
shown that the early visual experience actively alters the intrisic and extrinsic connections of auditory cortex,
and also alters the inhibitory circuitry. We are now investigating the
nature of these changes and whether they are responsible for creating
visual response properties in auditory cortex. We are also interested
in the molecular mechanisms underlying specification of sensory cortex and
the guidance of thalamocortical axons. This
work has been funded by the NSF, Whitehall Foundation, Fight
for Sight, and the Deafness Foundation.
Background Publications:
·
Pallas, S.L., P. Wenner , C. Gonzalez-
Islas , M. Fagiolini , K. Razak
, G. Kim, D. Sanes , and B. Roerig
(2006) Developmental plasticity of inhibitory circuitry. J. Neurosci ., 26 (41): 10358-10361. (click for pdf)
·
Pallas, S.L., M. Xu , and K.A. Razak ( 2006)
Influence of thalamocortical activity on sensory
cortical development and plasticity. In: R. Erzurumlu , W. Guido, Z.
Molnar, (eds.) Development and Plasticity in Sensory Thalamus and Cortex. Kluwer Academic/ Plenum Publishers, New York. (click for pdf)
·
Pallas, S.L. (2005) Pre- and postnatal
sensory experience shapes functional architecture in the brain. Chapter 1
in B. Hopkins & S.P. Johnson (Eds.): Prenatal Development of Postnatal
Functions. Advances in Infancy
Research, Volume 14. Praeger , Westport
, CT , pp. 1-30.
·
Pallas, S.L. (2002) Cross-modal plasticity
as a tool for understanding ontogeny and phylogeny of cerebral cortex.
Chapter 12 in A. Shüz and R. Miller (eds.)
Cortical Areas: Unity and Diversity, Harwood Academic Publishers, London. Conceptual
Advances in Brain Research 5: 245-272.
·
Pallas, S.L. (2001) Intrinsic and extrinsic
factors shaping cortical identity. Trends
in Neuros ciences 24
(7): 417-423. (click
for pdf)
Some Recent
Publications:
·
Razak, K.A. and S.L. Pallas (2007) Inhibitory plasticity facilitates recovery
of stimulus velocity tuning in the superior colliculus
after chronic NMDA receptor blockade. J. Neurosci. 27(27): 7275-7283. (click for pdf)
·
Carrasco, M.M. and S.L. Pallas (2006) Early visual experience
prevents but cannot reverse deprivation-induced loss of refinement in
adulthood. Visual Neuroscience, 23(6):
845-852. (click
for pdf)
·
Razak , K. A. and S.L. Pallas ( 2006 ) Dark rearing reveals
the mechanism underlying stimulus size tuning of superior colliculus neurons. Visual
Neuroscience, 23(5): 741-748 .
(click
for pdf)
·
Razak , K. A. and
S.L. Pallas ( 2005) Neural mechanisms of stimulus velocity tuning in
the superior colliculus. J. Neurophysiol. 94(5):3573-3589.
(click for pdf)
·
Carson
, J.P., T. Ju , H.-C. Lu, C. Thaller
, M. Xu , S.L. Pallas, M.C. Crair
, J. Warren, W. Chiu, and G. Eichele (2005)
A digital atlas to characterize the mouse brain transcriptome
. PLOS Computational Biology 1(4):
e41. (click
for pdf)
·
Carrasco, M.M., K.A. Razak
and S.L. Pallas (2005) Visual experience is necessary for
maintenance but not development of refined retinotopic
maps in superior colliculus. J. Neurophysiol . 94:
1962-1970. (click
for pdf)
·
Razak , K.A., L.
Huang, and S.L. Pallas (2003) NMDA receptor blockade in the superior colliculus increases receptive field size without
altering velocity and size tuning. J. Neurophysiol . 90: 110-119. (click for pdf)
·
Huang, L. and S.L. Pallas (2001) NMDA
antagonists in the superior colliculus prevent
developmental plasticity but not visual transmission or map compression. J. Neurophysiol . 86:
1179-1194. (click for pdf)
·
Gao , W.-J., A. Wormington , D. Newman, and S.L. Pallas (2000)
Development of inhibitory circuitry in visual and auditory cortex of
postnatal ferrets: immunocytochemical
localization of calbindin and parvalbumin
-containing neurons. J. Comp. Neurol . 422: 140-157. (click for pdf)
·
von Melchner , L., S. L. Pallas and M. Sur
(2000) Visual behavior induced by retinal projections directed to the
auditory pathway. Nature 404:871-875.
(click for pdf)
To see a complete
c.v., click here
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