BRAIN RESPONSES OF SHORT-WAVELENGTH CONES

1. Responses of the short wavelength sensitive (S-) cone mechanism wer e detected in the visual evoked response (VER) of the brain using ganz feld flashes in the presence of a rod saturating ganzfeld background ( 17,000 phot td). 2. These S-cone responses were exposed by matching sp ectrally different stimuli to be approximately equivalent for generati ng electroretinograms (ERGs) mediated by the long (L-) and middle (M-) wavelength sensitive cones. The S-cone VER has a relatively-larger am plitude, a later implicit time and a greater tendency to induce oscill ations. Because of its longer latency, 130 ms for the inion positive r esponse, the S-cone VER has been labeled component 3 to distinguish it from two earlier inion positive VER components (1 and 2) which are pr oduced exclusively or almost exclusively by L and M cones. 3. Componen ts 1 and 2 have implicit times of 64 and 98 ms respectively. Because c omponent 1 is faster, smaller and does not seem to interact with the S -cone mechanism, it is suggested that it may reflect the magnocellular pathway.