Multimodal sensory integration in weakly electric fish: a behavioral account.

The ability to integrate multisensory information is a fundamental characteristic of the brain serving to enhance the detection and identification of external stimuli. Weakly electric fish employ multiple senses in their interactions with one another and with their inanimate environment (electric, visual, acoustic, mechanical, chemical, thermal, and hydrostatic pressure) and also generate signals using some of the same stimulus energies (electric, acoustic, visual, mechanical). A brief overview provides background on the sensory and motor channels available to the fish followed by an examination of how weakly electric fish 'benefit' from integrating various stimulus modalities that assist in prey detection, schooling, foraging, courtship, and object location. Depending on environmental conditions, multiple sensory inputs can act synergistically and improve the task at hand, can be redundant or contradictory, and can substitute for one another. Over time, in repeated encounters with familiar surrounds, loss of one modality can be compensated for through learning. Studies of neuronal substrates and an understanding of the computational algorithms that underlie multisensory integration ought to expose the physiological corollaries to widely published concepts such as internal representation, sensory expectation, sensory generalization, and sensory transfer.