The neural biology of Antarctic fish: Measurements of the neural activity from fish semicircular canals in response to head movement

The input and outputs of a well defined reflex pathway (the vestibulo-ocular reflex - VOR) was described in Antarctic fish to assess the mechanisms of neural cold adaptation at low temperatures. The neural activity from fish semicircular canals was recorded in response to head movement. As the reflex is bisynaptic, with two intercellular contacts and one interneuron within the central nervous system, the results provide information about the function within the brain of cold-adapted fish. Five comprehensive sets of recordings were made at different frequencies and amplitudes of rotation on a turntable. This work was further investigated in a subsequent season using a specially designed turntable system, to determine the VOR over a wide range of stimulus frequencies and combined with neurophysiological recordings from primary vestibular afferents, secondary cells and abducens motor neurons to provide a functional description of the VOR as a model system in which to evaluate brain function at low temperature. Stable recordings from secondary vestibular cells responding to horizontal head rotation were also obtained and the results were analysed using standard electrical engineering techniques to provide an explicit model of vestibular function and brain processes at low temperature.