Analysis of response patterns of LGN cells.

A detailed an alysis was mad e of th e response characteristic s of single cells in th e lat eral geniculate nucleus of the macaqu e monkey. Th e goa l was to understand how the se cells cont rib ute to th e proc essing of visual information. Dat a were an alyzed from a representative sa mple of 147 cells, whose respons es to eq ua l-energy spectra (prese nte d as diffuse flash es of monocbromatic light) were record ed at three radiance levels. On the basis of th eir responses, th e cells were di vided int o two ge nera l classes : (a) spect ra lly nonopponent cells which respond to all wavelengths with either an increase or decr ease in tiring rat e, (h) spec t ra lly opponent cells (ab out two-th irds of th e sa mple) which respond with a n increase in firing ra te to so me parts of the spect rum an d a dec rease to ot her par ts. Four typ es of op ponent cells were found : (i) red excita tory and gree n inh ibit ory (+ R-G), (ii) gre en excitatory an d red inhibitory (+G-R), (iii) ye llow excita tory a nd blu e inhibitory (+ Y-11), (iv) blu e excita tory and yellow inhibito ry (+ ll-V). Co mpa risons with psycho-ph ysical dat a ind icat ed that nonopp oncnt cells transmit brightness inform a tion ; opponent cells , however, carry inf ormation ab out color, th e hu e of a light being det ermined by th e relat ive responses of the four types. The sa tura tion of spec t ra l light s appears to be related to th e differences in respo nses of opponent and non-opp onent cells.