VISUALLY EVOKED CALCIUM ACTION-POTENTIALS IN CAT STRIATE CORTEX

EARLY intracellular studies of cerebral cortical neurons indicated tha t synaptic input evokes dendritic action potentials that convey inform ation towards the soma(1). Subsequent work in vitro established that n eocortical neurons produce dendritic Ca2+ action potentials(2-5). To d etermine whether natural stimuli elicit Ca2+ spikes, we combined the t echniques of whole-cell recording(6,7), pharmacology(8) and quantitati ve receptive field mapping(9). Our findings show that visual stimulati on routinely evoked Ca2+ spikes in distinct functional(10) and anatomi cal(11) classes of cells in different layers of the cat striate cortex (12). Hence regenerative Ca2+ potentials appear to play a role in both the initial and later stages of cortical sensory processing.