The absence of brain-specific link protein Bral2 in perineuronal nets hampers auditory temporal resolution and neural adaptation in mice.

摘要

Brain-specific link protein Bral2 represents a substantialcomponent of perineuronal nets (PNNs) enwrapping neurons inthe central nervous system. To elucidate the role of Bral2 inauditory signal processing, the hearing function in knockoutBral2-/- (KO) mice was investigated using behavioral andelectrophysiological methods and compared with wild typeBral2+/+ (WT) mice. The amplitudes of the acoustic startle reflex(ASR) and the efficiency of the prepulse inhibition of ASR (PPI ofASR), produced by prepulse noise stimulus or gap in continuousnoise, was similar in 2-week-old WT and KO mice. Over the2-month postnatal period the increase of ASR amplitudes wassignificantly more evident in WT mice than in KO mice. Theefficiency of the PPI of ASR significantly increased in the 2-monthpostnatal period in WT mice, whereas in KO mice thePPI efficiency did not change. Hearing thresholds in 2-month-oldWT mice, based on the auditory brainstem response (ABR)recordings, were significantly lower at high frequencies than inKO mice. However, amplitudes and peak latencies of individualwaves of click-evoked ABR did not differ significantly betweenWT and KO mice. Temporal resolution and neural adaptationwere significantly better in 2-month-old WT mice than inage-matched KO mice. These results support a hypothesis thatthe absence of perineuronal net formation at the end of thedevelopmental period in the KO mice results in higher hearingthreshold at high frequencies and weaker temporal resolutionability in adult KO animals compared to WT mice.