Systems neuroscienceSpectral integration in the inferior colliculus of the CBA/CaJ mouse
Section snippets
Experimental procedures
We recorded responses of single neurons in the IC of awake CBA/CaJ mice to single tones and combinations of tones. Animals used in the experiments were two to six months of age. As mice are nocturnal and we wanted their active period to be during the day, they were kept on a 12-h light/dark off/on schedule so that the lights were off during the day. Surgeries were performed early in the morning and electrophysiological recordings began around 10 a.m. of the same day. This increased the
Results
We obtained excitatory frequency tuning curves from 154 single units in the IC. Only responses localized to the central nucleus of the IC were included in the analyses. Characteristic frequencies ranged from 6 and 64 kHz, and there were two peaks in the CF distribution (Fig. 1A). One peak occurred at CFs around 20 kHz and the second peak occurred at CFs near 48 kHz. Of these 154 neurons, 49 (32%) were tuned to more than one frequency band and were classified as multiply tuned. Responses to
Discussion
Fig. 7 summarizes response properties recorded in the mouse IC. The 32% of multiply tuned neurons is similar to the percentage found in the mustached bat IC using a similar experimental paradigm and awake stereotaxic apparatus (Portfors and Wenstrup, 2002). This is higher than has been reported in other species (mouse: Egorova et al., 2001; guinea-pig: LeBeau et al., 2001). Egorova and colleagues found only 6.2% of neurons in the IC of mouse to be multiply tuned. In their study, the frequency
Acknowledgments
This work was supported by NIH/NIDCD grant 04733 to C.V.P. and an underrepresented minorities supplement to R.A.F. We thank Deborah Langley and Don Gans for technical assistance with this project.
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