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. 2003 Sep 17;23(24):8547–8557. doi: 10.1523/JNEUROSCI.23-24-08547.2003

Figure 1.

Figure 1.

Deducing retinocortical strength from monosynaptic retinothalamic and thalamocortical connections. The divergence from a single RGC to multiple thalamic (LGN) cells and subsequent reconvergence to single cortical cells (V1) results in the need to account for multiple pathways, each with different strengths. Contribution (as defined in Materials and Methods) is used to measure the strength of monosynaptic connections. The RGC–LGN contributions shown are from an actual “triplet” recording: one RGC to two LGN cells (36%, 67%) (Usrey et al., 1998, 1999). Similarly, triplets with two LGN inputs to one cortical cell have been studied (Reid and Alonso, 1995; Alonso et al., 1996) (contributions of 2%, 4% are typical of geniculocortical connections). Even with these recordings, other pathways from a single RGC are not accounted for (question marks). Simultaneous recordings from a single RGC and a single cortical simple cell are technically straightforward and provide a direct estimate of the effectiveness of a single retinal afferent in driving a cortical simple cell.