Michael C. Crair

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In mammalian development, the refinement of topographical projections from the thalamus to the cortex is thought to arise through an activity-dependent process in which thalamic axons compete for cortical targets. In support of this view, if activity is altered during a critical period in early development, normal connectivity is disrupted. It has been(More)
The role of experience in the development of the cerebral cortex has long been controversial. Patterned visual experience in the cat begins when the eyes open about a week after birth. Cortical maps for orientation and ocular dominance in the primary visual cortex of cats were found to be present by 2 weeks. Early pattern vision appeared unimportant because(More)
During development, activity-dependent mechanisms are thought to contribute to the refinement of topographical projections from the thalamus to the cortex. Because activity-dependent increases in synaptic strength may contribute to the stabilization of synaptic connections, we have explored the mechanisms of long-term potentiation (LTP) at thalamocortical(More)
The morphological and functional development of the vertebrate nervous system is initially governed by genetic factors and subsequently refined by neuronal activity. However, fundamental features of the nervous system emerge before sensory experience is possible. Thus, activity-dependent development occurring before the onset of experience must be driven by(More)
Although it is widely accepted that molecular mechanisms play an important role in the initial establishment of retinotopic maps, it has also long been argued that activity-dependent factors act in concert with molecular mechanisms to refine topographic maps. Evidence of a role for retinal activity in retinotopic map refinement in mammals is limited, and(More)
The regulation of NMDA receptor (NMDAR) subunit composition and expression during development is thought to control the process of thalamocortical afferent innervation, segregation, and plasticity. Thalamocortical synaptic plasticity in the mouse is dependent on NMDARs containing the NR2B subunit, which are the dominant form during the "critical period"(More)
Experimental studies over the past year have shown that neural activity has a range of effects on the development of neural pathways. Although activity appears unimportant for establishing many aspects of the gross morphology and topology of the brain, there are many cases where the presence of neural activity is essential for the formation of a mature(More)
Chicken ovalbumin upstream promotor-transcription factor I (COUP-TFI), an orphan member of the nuclear receptor superfamily, is highly expressed in the developing nervous systems. In the cerebral cortex of Coup-tfl mutants, cortical layer IV was absent due to excessive cell death, a consequence of the failure of thalamocortical projections. Moreover,(More)
In the primary visual cortex of monkey and cat, ocular dominance and orientation are represented continuously and simultaneously, so that most neighboring neurons respond optimally to visual stimulation of the same eye and orientation. Maps of stimulus orientation are punctuated by singularities referred to as "pinwheel centers," around which all(More)
The significance of functional maps for cortical plasticity was investigated by imaging of intrinsic optical signals together with single-unit recording in kittens. After even a brief period of monocular deprivation during the height of the critical period, only isolated patches of visual cortex continued to respond strongly to the closed eye. These(More)