Discrete uni- and multimodal mechanisms control sensorimotor gating of goldfish startle

CURTIN, PAUL C.; COHEN, SAMANTHA S.; MEDAN, VIOLETA; KARAPETYAN, SHUSHANIK; NEUMEISTER, HEIKE; PREUSS, THOMAS

College Park, Maryland

Congreso; Tenth International Congress of Neuroethology; 2012

International Society for Neuroethology

Sensorimotor gating mechanisms regulate the integration of sensory information in decision-making motor systems. These effects can be quantified in pre-pulse inhibition (PPI) paradigms, wherein weak (subthreshold prepulse) stimuli are used to modify the response to subsequent strong (suprathreshold pulse) stimuli presented short (20-1000 ms) intervals apart. Importantly, although PPI can be activated by visual and/or auditory prepulse stimuli, the mechanisms that integrate multiple afferent modalities are largely unknown. Here, we applied multi-modal PPI paradigms to study the integration of visual and auditory sensory modalities in the startle behavior of goldfish, and recorded soma-dendritic integration in the decision-making neuron (Mauthner cell) that triggers the behavior. Preliminary results indicate two main effects. First, the sequential order of stimulus modalities determines the sensorimotor gating effects evoked by pre-pulse stimuli. Auditory pre-pulse stimuli typically evoke attenuation of both visual and auditory startle responses. Visual pre-pulses, however, evoke inhibition of visual startle responses, but facilitate auditory startle responses. Secondly, our results show that the salience of visual pre-pulse stimuli is also an important determinant of sensorimotor gating effects. We tested this by comparing prepulse-gating effects evoked by flashes of light and by projected images of rapidly expanding discs (i.e., “looming” stimuli). We found that whereas light-flash prepulses evoke inhibition of the startle response, looming visual-prepulse stimuli evoke the opposite, a facilitation of startle. In sum, these findings suggest that plasticity in sensorimotor gating is driven by discrete uni- and multimodal mechanisms. Functionally, the sequence and kind of stimuli likely have biological relevance for adaptive behavioral decisions.