Our laboratory studies spontaneous electrical activity in the developing brain. Spontaneous activity occurs in virtually every structure of the mammalian central nervous system and, in each structure, occurs as waves that propagate across large regions. It is not known how these waves are generated.
We have discovered that in the cerebral cortex, waves of activity are initiated at two specific pacemaker sites. we are using transgenic mice in which specific populations of neurons are labeled with GFP to identify the pacemaker neurons and determine what intrinsic and synaptic properties cause them to assume a pacemaking role. We use calcium imaging, patch clamp, and immunocytochemical methods.
Our current work indicates that the pacemaker for waves when they first start to be generated, one day before birth, is comosed of migrating GABAergic neurons. Several days after birth, as GABA becomes an inhibitory transmitter, the pacemaking function is passed on to the glutamatergic neuron population. We are investigating how this switchover occurs and what its implications are for early brain development.