Research data for paper ‘Interneuronal mechanisms for learning-induced switch in a sensory response that anticipates changes in behavioural outcomes’.

Sensory cues in the natural environment predict reward or punishment, important for survival. For example, the ability to detect attractive tastes indicating palatable food is essential for foraging whilst the recognition of inedible substrates prevents harm. Whilst some of these sensory responses are innate, they can undergo fundamental changes due to prior experience associated with the stimulus. However, the mechanisms underlying such behavioural switching of an innate sensory response at the neuron and network levels require further investigation. We used the model learning system of Lymnaea stagnalis [1-3] to address the question of how an anticipated aversive outcome reverses the behavioural response to a previously effective feeding stimulus, sucrose. Key to the switching mechanism is an extrinsic inhibitory interneuron of the feeding network, PlB (pleural buccal [4, 5]), which is inhibited by sucrose to allow a feeding response. After multi-trial aversive associative conditioning, pairing sucrose with strong tactile stimuli to the head, PlB’s firing rate increases in response to sucrose application to the lips and the feeding response is suppressed; this learned response is reversed by the photoinactivation of a single PlB. A learning-induced persistent change in the cellular properties of PlB that results in an increase rather than a decrease in its firing rate in response to sucrose provides a neurophysiological mechanism for this behavioural switch. A key interneuron, PeD12 (Pedal-Dorsal 12), of the defensive withdrawal network [5, 6] does not mediate the conditioned suppression of feeding but its facilitated output contributes to the sensitization of the withdrawal response.