The contribution of inferior colliculus activity to the auditory brainstem response (ABR) in mice

Abstract

In mice, the auditory brainstem response (ABR) is frequently used to assess hearing status in transgenic hearing models. The diagnostic value of the ABR depends on knowledge about the anatomical sources of its characteristic waves. Here, we studied the contribution of the inferior colliculus (IC) to the click-evoked scalp ABR in mice. We demonstrate a non-invasive correlate of the IC response that can be measured in the scalp ABR as a slow positive wave P with peak latency 7-8 ms when recorded with adequate band-pass filtering. Wave P showed close correspondence in latency, magnitude and shape with the sustained part of evoked spiking activity and local field potentials (LFP) in the central nucleus of the IC. In addition, the onset peaks of the IC response were related temporally to ABR wave V and to some extent to wave IV. This relation was further supported by depth-dependent modulation of the shape of ABR wave IV and V within the IC suggesting generation within or in close vicinity to the IC. In conclusion, the slow ABR wave P in the scalp ABR may represent a complementary non-invasive marker for IC activity in the mouse. Further, the latency of synchronized click-evoked activity in the IC supports the view that IC contributes to ABR wave V, and possibly also to ABR wave IV.

Adaptation and spectral enhancement at auditory temporal perceptual boundaries - Measurements via temporal precision of auditory brainstem responses

“…Besides the expected latency differences of about 1 ms between the wave peaks (Table 1), which relate to synaptic levels in the ascending auditory pathway [28,29,32,34], we found an average latency difference of 0.342 ms related to P1 when generated by high (50 kHz) vs. low (3.8 kHz) tone stimulation (Table 1, Δ D - A ). The frequency of 3.8 kHz is at the low end, 50 kHz at the high end of characteristic frequencies of AN fibers and IC neurons in NMRI mice [67,68] and other mouse strains [69–71].…”

“…The perceptual boundary near 100 ms depending on the duration of inter-sound intervals [15,16] was reflected in the beginning of significant adaptation of latencies and the increase of latency jitter at P5 for ISIs < ~100 ms (experiment C, Figs 5A, 6A and 6C). Thus, we can state that optimal perception of wriggling call series in one acoustic stream with ISIs > 100 ms happens when the sound onset responses at P5, most probably representing IC-responses in the mouse [32–34], are largely free from adaptation and able to follow with full temporal precision the sound onsets. Likewise in human perception, series of two tones with frequencies within one critical band are integrated in one perceptual stream, if the ISIs are longer than about 100 ms [15].…”

“…In the mouse, peak 1 (P1) seems to emanate from the cochlea (CO), i.e. from cochlear hair cells and the auditory nerve, peaks 2, 3, 4, 5 (P2, P3, P4, P5) mainly from cell groups in the cochlear nucleus (CN) ipsilateral to the stimulated ear, in the contralateral superior olivary complex (SOC), in the contralateral lateral lemniscus (LL) and in the IC, respectively [28,32–34]. Major topics of ABR studies in mice included development, aging, genetics, and pathologies of hearing simple sounds such as clicks, noise and tone bursts [28,31,35–45].…”

Differences in Stress-Induced Modulation of the Auditory System Between Wistar and Lewis Rats

“…In our present investigation, we focused on protein composition in the inferior colliculi rather than the auditory cortex, because the inferior colliculus actively contributes to the generation of the evoked ABRs (Land et al, 2016 ). We reasoned that the functional changes seen in ABR profiles might be linked to changes occurring in AMPA, Arc, Syt1, Syt12, at the protein level, as those are involved in the synaptogenesis.…”

Towards the optical cochlear implant: optogenetic approaches for hearing restoration

“…In a first proof‐of‐principle study (Hernandez et al , ), optogenetic activation of the auditory system was reported in transgenic mice broadly expressing ChR2 in neural structures under the Thy1.2 promoter (Arenkiel et al , ). The feasibility of optogenetic excitation of the auditory system was first demonstrated by recordings of auditory brainstem responses (ABR): ABRs are far‐field potentials, reflecting the synchronous activation of the auditory system up to the auditory midbrain and are typically characterized by five waves (originating from activation of the auditory nerve, a set of nuclei in the auditory brainstem and finally the inferior colliculus (Henry, ; Land et al , )) when elicited by acoustic stimulation (aABRs). Using optogenetic (oABR) stimulation, it could be demonstrated that cochlear optogenetics is capable of evoking potentials of up to 2.5 mV amplitude.…”