Identification of optic lobe neurons of locusts by video films

The response characteristic of visual interneurons of the brain was studied in Locusta migratoria and Schistocerca gregaria. Alternating light and dark, moving dots, bars and striped patterns were used for stimulation (Fig. 3). These stimuli were recorded with a video system and replayed on TV-screens during the experiment to allow fast testing of the sensitivity of a neuron to different stimuli during the limited time of intracellular recording. Data were stored and analysed by computer. The neurons were anatomically identified by intracellular injection of Lucifer yellow. Neutral (“non-visual”) and several classes of spiking interneurons of the medulla and lobula sensitive to visual stimuli could be distinguished by anatomical and physiological characteristics (Figs. 1, 2). The visual cells respond either to light-on, or to light-off, flicker, moving small dots, bars or striped patterns (Figs. 2–6). One class is directionally sensitive to pattern movement either from back to front or into the reverse direction (horizontal cells; Figs. 7, 8) and may therefore be involved in optomotor flight control.