Inferior Colliculus Approach in a Rat

Abstract

The inferior colliculus (IC) of the rat is a well-investigated and understood model for topographical mapping of the frequency domain (Clopton et al., Exp Neurol 42(3):532–540, 1974; Kelly and Masterton, J Comp Physiol Psychol 91(4): 930–936, 1977; Borg, Hear Res 8(2) 101–115, 1982; Ryan et al., Hear Res 36(2–3): 181–189, 1988; Zhang et al., Hear Res 117(1–2):1–12, 1998). As a central hub for binaural auditory processing in the midbrain (Du et al., Eur J Neurosci 30(9): 1779–1789, 2009) it shows a variety of response patterns to a given complex auditory stimulation (Kelly et al., Hear Res 56(1–2):273–280, 1991; Kelly and Li, Hearing Res 104:112–126, 1997). It is therefore a major target for neuroscientific approaches of the ascending and descending auditory pathway. Approaching the IC is, however, not only valuable for scientists interested in auditory processing, but also for students learning the proceedings of standard electrophysiological experimentation. In addition, engineers of biomedical devices (e.g., flexible penetrating electrodes) can take benefit from the IC approach (Kisban et al., Conference proceedings: annual international conference of the IEEE Engineering in Medicine and Biology Society IEEE Engineering in Medicine and Biology Society Conference, 2007:175–178). A critical test of the suitability of shaft electrodes is their successful implantation in vivo. The steady tonotopic structure of the IC and its three subdivisions provides an almost perfect anatomic testing ground (Saldana and Merchan, J Comp Neurol 319(3):417–437, 1992). Additionally, the anatomical procedure to access the IC requires only a medium level of surgical skills and the testing apparatus can be kept relatively small and manageable. The current study describes the necessary anatomical steps and materials needed for the aforementioned scenarios.