POSTER PRESENTATION Open Access Encoding of touch location and intensity by neurons of the medicinal leech Hirudo medicinalis

Even in small neuronal systems sensory stimuli evoke pre-cise behavioral responses. The leech, possessing one of the smallest neuronal systems with ~10.000 neurons, shows as a response to a touch of the skin a locally limited bend away from this touch [1]. This local bending reflex is known to be initiated by only two mechanosensory cells (P ‘pressure ’ cells) with overlapping receptive fields and to depend both on touch location and touch intensity [2]. Behaviorally, the animal displays a surprisingly precise per-formance, discriminating touch locations which are only 9° of the body circumference apart [3]. Thomson and Kristan investigated in their study [3] the encoding of stimulus location based on two P cells with overlapping receptive fields. They analyzed the relative response features of the neuronal responses, in particula