Single unit activity in the visual pathway of the butterfly Heliconius erato

Abstract

Extracellular potentials were recorded from the optic lobes, protocerebrum, and ventral nerve cord of the neotropical butterfly Heliconius erato adanis. Except for pure ‘on’ and ‘off’ fibres, all neurons demonstrated a dark discharge. Neurons demonstrating a special sensitivity to unidirectional movement, jittery movement, dimming, unilateral stimulation, illumination level, etc., were studied. It is questionable whether neurons responding to such stimuli are homologous in all insects. A hypothesis concerning the neural processing of colour information is presented.