(full paper is archived in the Miller Library)
Title: Startle-response potentials in the
retina and optic tectum of adult zebrafish
Student Author(s): Gu, Emily
Ma, Jeffrey
Faculty Advisor(s): Thompson, Stuart
Pages: 29
Location: Final Papers Biology 176H
Date: June 2006
Abstract: Although the functional role of
the optic tectum has yet to be well characterized
in teleosts, it is thought to be responsible for
initiating and coordinating visuomotor behaviors
associated with the looming response. In this
study, behavioral and electrophysiological
responses to the looming stimulus were measured
by differential suction electrodes at the optic
tectum and retinal ganglion cells of adult male
zebrafish (Brachydanio rerio). The looming
stimulus was simulated by a light-emitting diode
and by increasisng irradiance durations.
Responses to off-light events were found at both
the retina and optic tectum, suggesting that
light-induced startle responses begin as early in
the visual synaptic pathway as the retina.
However, several differences in signal shape and
amplitude between recordings at these two regions
suggest that higher-order visual processing of
on- and off-responses occurs at the optic tectum.
Latency times were measured between the
presentation of the stimulus and the onset of the
response, but data are currently inconclusive.
Habituation was observed through decreases in
startle response as a function of flash
repetition. Future studies are necessary to
correlate electrode position with signal strength
to resolve neural organization at the optic
tectum. Other parameters such as flash duration,
interstimulus interval, and age of the zebrafish
can also be varied to obtain a more complete
understanding of the startle response.