Voss et al. 10.1073/pnas.0611515104. |
Fig. 5.
Effect of Diazepam on brain surface auditory-evoked responses. Auditory-evoked potentials were recorded with two (left and right) arrays of epidural gold-plated pin electrodes before (blue traces) and after (red traces) Diazepam (40 µl, 1.66 mg/ml in normal saline, injected i.m.). The bottom black trace depicts a female call stimulus. Traces shown are representative traces from a >150-day-old adult zebra finch. The small differences in shapes between responses before and after Diazepam are consistent with normal trial to trial variability. The schematic diagram on the right depicts the positions of the active and reference/ground (Ref/G) electrodes.
Fig. 6.
Effect of Diazepam on field potential responses in NCM. Field potential recordings (blue and red traces) from the right nidopallium caudalis medialis were conducted with a blunt Teflon-coated tungsten electrode (125 µm diameter). The black traces represent the conspecific song motif stimulus used. Traces shown are representative traces from a >150-day-old adult zebra finch. There is a small difference in the shape of the field potential response before (Control) and after Diazepam (Diazepam).
SI Text
Sedation with Diazepam
We have conducted chronic in vivo electrophysiological recordings in eight adult zebra finches before and after an intramuscular injection of Diazepam at the same dose as was used in the fMRI experiments. These recordings involved averaged auditory evoked potentials (in five birds) detected with bilateral arrays of 12 epidural electrodes and depth field potential recordings (in three birds) from NCM with Teflon-coated tungsten electrodes (125 µm diameter). There was no significant difference in the amplitude or time course, and only slight alterations in shape, between responses before and after injection of Diazepam (see SI Figs. 5 and 6). The dose used in our experiments is less than that (7.5 mg/kg body weight) used to show an increased BOS sensitive response in HVC by Cardin and Schmidt (1). At our dose the bird is sluggish, and it perches on the floor rather than on the perch. The effect sets in within 5 min and lasts for ~2-3 h.
1. Cardin JA, Schmidt MF (2003) J Neurophysiol 90:2884-2899.