1. Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA
2. Present address: Department of Physiology, School of Medical Sciences, University Walk, Bristol BS81TD, UK.

Correspondence to: Barry W. Connors¹ Correspondence and requests for materials should be addressed to B.W.C. (e-mail: Email: Barry_Connors@brown.edu).

Abstract

Many representations of sensory stimuli in the neocortex are arranged as topographic maps. These cortical maps are not fixed, but show experience-dependent plasticity¹,². For instance, sensory deprivation causes the cortical area representing the deprived sensory input to shrink, and neighbouring spared representations to enlarge, in somatosensory³, auditory⁴ or visual cortex⁵. In adolescent and adult animals, changes in cortical maps are most noticeable in the supragranular layers at the junction of deprived and spared cortex^{6, 7, 8, 9}. However, the cellular mechanisms of this experience-dependent plasticity are unclear. Long-term potentiation and depression have been implicated^{10, 11, 12}, but have not been proven to be necessary or sufficient for cortical map reorganization. Short-term synaptic dynamics have not been considered. We developed a brain slice preparation involving rat whisker barrel cortex in vitro. Here we report that sensory deprivation alters short-term synaptic dynamics in both vertical and horizontal excitatory pathways within the supragranular cortex. Moreover, modifications of horizontal pathways amplify changes in the vertical inputs. Our findings help to explain the functional cortical reorganization that follows persistent changes of sensory experience.