Neural Mechanisms Underlying Adult Ocular Dominance Plasticity: Hebbian or Homeostatic?

Daniel Tso, PhD
Associate Professor of Neurosurgery,
Neuroscience and Physiology,
& Ophthalmology and Visual Sciences
SUNY Upstate Medical University
Syracuse, NY

Recent studies in adult humans have shown that short-term deprivation of one eye (STMD, 1-3hrs) dramatically shifts the balance in favor of this eye for over an hour afterwards. This surprising result runs counter to the classical understanding of both the limits of adult cortical plasticity as well as the Hebbian nature of monocular deprivation.  Thus the STMD paradigm has uncovered a poorly understood yet important feature of early binocular integration. We have confirmed this striking observation in initial functional imaging studies of primate visual cortex, thereby also showing a cortical locus. As pattern deprivation also elicits this non-Hebbian STMD effect and its recovery behavior is dependent on binocular interactions, the underlying neural mechanisms cannot be retinal in origin. These STMD studies have been extended with multi-electrode single unit recordings, LFP recordings and human fMRI, to further reveal aspects of the underlying cortical mechanisms responsible for this novel form of adult homeostatic plasticity.

Hosts: Paul Worley, MD & Seung-Eon Roh, PhD