Figure 1.

Spatiotemporal reactivation of the contralateral visual cortex by visual and cross-modal inputs after monocular enucleation (ME) in adult mice. (A) Layer- and time-specific recovery of neuronal activity in the left visual cortex subsequent to removal of the right eye at an adult age of P120 is illustrated. Molecular activity profiles of the visual cortex have been assessed by the zif268 mRNA expression analysis around Bregma level −3.40 mm. For each section, the original autoradiogram displaying the deprived (left) visual cortex is shown in gray and its matching pseudo-colored mirror image. The medial and lateral extent of the left visual cortex is marked by the two large arrowheads whereas small arrowheads delineate the interareal boundaries. The activity in the central binocular cortex starts to expand supragranularly (asterisk first and second panel) between 1 and 3 weeks post-ME. Between 3 and 5 weeks, infragranular layers also start to show increased reactivation. (B) Anterograde and retrograde transport of fluororuby upon injection in V2M of a 7wME mouse. b: Detail of Fluororuby signal at the location of somatosensory cortex: tracer is transported in an anterograde way to axon terminals in layers V and VI, while supragranular layers II/III contain retrogradely labeled cell bodies and dendrites. c: Detail of anterogradely labeled fibers in contralateral V2M. d: Detail of retrogradely labeled pyramidal cells in layers II and III of ipsilateral/adjacent somatosensory cortex. (C) Subsequent whisker manipulations in 7wME mice were employed in order to verify the functional relevance of the intermodal connections in the ME-induced reactivation profile. Somatosensory deprivation (SD) by trimming the right-side vibrissae results in decreased visual cortex activity whereas somatosensory stimulation (SS) through exposure to toys and novel objects in the dark increased activity, especially in V2M. Adapted from Van Brussel et al. (2011).