286
arrayed in different orientations. As the projections may act to restrict water fl ow
along the neuromast, swimming fi sh would have a proportional of their neuromasts
not impacted by movement/water fl ow and remain sensitive to acoustic stimulus.
Additionally, the utricular organs act as linear accelerometers, and once the fi sh
achieve constant velocity they could regain full sensitivity to acoustic input.
Although in toadfi sh, the short, intermittent swimming motions make achieving
constant velocity problematic, other species that display constant, steady swimming
could maintain auditory sensitivity. Additionally, as both the lateral line and utricle
are innervated by fi rst order neurons, central nervous system fi ltering may also factor in modulating sensitivity.
4.3 Future Directions
It is equally important to investigate the effects of simultaneous bimodal sensory
input into two systems. Preliminary experiments have proven the effi cacy of
implanting bilateral electrodes in the lateral line (Radford and Mensinger, unpublished). Future experiments aim to implant electrodes in both the lateral line and
utricle to determine how these systems encode and integrate similar stimuli, and
determine how the utricle and lateral line function during free swimming and sound
localization behavior.
5 Summary
The neural telemetry tag has allowed exploration of multiple sensory input such as
self-generated movement and sound in both the utricle and lateral line. It has allowed
neural sensitivity to be explored in freely moving fi sh without the complications of
anesthesia. Both systems were sensitive to sounds consistent with toadfi sh vocalizations and showed directional sensitivity, indicating a role in sound localization.
Acknowledgements I am grateful to Karen Maruska (utricle) and Craig Radford (lateral line) for
performing the bulk of the experiments and data analysis reported in this chapter and to the Grass
foundation for providing their support. Thanks to Lucy Palmer and Max Deffenbaugh for initial
help in developing the tag. Funding was provided by NSF grants IOS 0316130, 0843735, and
1354745.
I would also thank Dick Fay and Art Popper for their contributions to fi sh bioacoustics. I fi rst
met Dick Fay while I was a post-doc in the Highstein lab during our summer toadfi sh research at
the Marine Biological Laboratory in Woods Hole, Massachusetts. While our study sites in the
toadfi sh brain were just mm apart, our interests at the time were quite divergent as Dick was investigating the saccule and I was concentrating on nerve regeneration and developing the telemetry
tag. Dick was always quite supportive and encouraging of my research, and I appreciated his input
and guidance. Although his shaker table and experiments were cutting edge, his patience for neurophysiology was certainly old school. There was never any need to ask Dick how the experiments
were going, because the frequency of his outdoor “breaks” were inversely correlated with
A.F. Mensinger
arrayed in different orientations. As the projections may act to restrict water fl ow
along the neuromast, swimming fi sh would have a proportional of their neuromasts
not impacted by movement/water fl ow and remain sensitive to acoustic stimulus.
Additionally, the utricular organs act as linear accelerometers, and once the fi sh
achieve constant velocity they could regain full sensitivity to acoustic input.
Although in toadfi sh, the short, intermittent swimming motions make achieving
constant velocity problematic, other species that display constant, steady swimming
could maintain auditory sensitivity. Additionally, as both the lateral line and utricle
are innervated by fi rst order neurons, central nervous system fi ltering may also factor in modulating sensitivity.
4.3 Future Directions
It is equally important to investigate the effects of simultaneous bimodal sensory
input into two systems. Preliminary experiments have proven the effi cacy of
implanting bilateral electrodes in the lateral line (Radford and Mensinger, unpublished). Future experiments aim to implant electrodes in both the lateral line and
utricle to determine how these systems encode and integrate similar stimuli, and
determine how the utricle and lateral line function during free swimming and sound
localization behavior.
5 Summary
The neural telemetry tag has allowed exploration of multiple sensory input such as
self-generated movement and sound in both the utricle and lateral line. It has allowed
neural sensitivity to be explored in freely moving fi sh without the complications of
anesthesia. Both systems were sensitive to sounds consistent with toadfi sh vocalizations and showed directional sensitivity, indicating a role in sound localization.
Acknowledgements I am grateful to Karen Maruska (utricle) and Craig Radford (lateral line) for
performing the bulk of the experiments and data analysis reported in this chapter and to the Grass
foundation for providing their support. Thanks to Lucy Palmer and Max Deffenbaugh for initial
help in developing the tag. Funding was provided by NSF grants IOS 0316130, 0843735, and
1354745.
I would also thank Dick Fay and Art Popper for their contributions to fi sh bioacoustics. I fi rst
met Dick Fay while I was a post-doc in the Highstein lab during our summer toadfi sh research at
the Marine Biological Laboratory in Woods Hole, Massachusetts. While our study sites in the
toadfi sh brain were just mm apart, our interests at the time were quite divergent as Dick was investigating the saccule and I was concentrating on nerve regeneration and developing the telemetry
tag. Dick was always quite supportive and encouraging of my research, and I appreciated his input
and guidance. Although his shaker table and experiments were cutting edge, his patience for neurophysiology was certainly old school. There was never any need to ask Dick how the experiments
were going, because the frequency of his outdoor “breaks” were inversely correlated with
A.F. Mensinger