QUANTIFICATION OF EXCITATORY RECEPTIVE-FIELDS OF COMPLEX NEURONS IN CAT STRIATE CORTEX

Excitatory receptive field (ERF) response profiles and length summatio n functions were derived from complex neurones in cat striate cortex. Measured length summation was compared with summation predicted from i ntegration over ERF profiles. In a minority of neurones, measured and predicted summation were well matched. In the majority, whether end-st opped or not, responsiveness in length summation tests was appreciably greater than predicted for short stimuli, compared with ERF profiles. The mismatch was least in standard and greatest in special complex ne urones; in the latter group, response levels to long stimuli fell well below predicted levels. In end-stopped neurones the decremental porti on of length summation functions was not predicted by ERF profiles. Th ese results implicate the involvement of non-linear mechanisms, whereb y concomitant stimulation of central regions of the receptive field (R F) potentiate the efficacy of loci towards either end of the RF.