Figure 3. Two methods to investigate geniculocortical connections.

A, cross-correlation analysis. Correlogram and receptive fields illustrating a strong connection between a geniculate cell and a cortical simple cell. Data from Reid & Alonso (1995) and Alonso et al. (2001). B, STCSD. This method measures the current sinks generated by single geniculate afferents in the cortex. These current sinks are strong and spatially restricted. Left, sink of a geniculate afferent restricted to cortical layer 4 (arrows mark layer limits). The sink has three components: axonal response, synaptic delay and postsynaptic response. Right, horizontal cortical distribution of the current sink (red) and the synapses from a single X geniculate axon terminal (Humphrey et al. 1985). Reprinted with permission from Alonso & Swadlow (2005) and Jin et al. (2008b).