Object-specific adaptation in the auditory cortex of bats

Abstract

To identify behaviourally relevant sounds is an important function of the auditory system. Echolocating bats have to negotiate a wealth of sounds in the context of navigation and foraging. They must be able to detect relatively rare but behaviourally important echoes and segregate them from a large number of unimportant background echoes. For this, the bat auditory system might rely on neural deviance detection, a process influencing the excitability of a neuron depending on the frequency of occurrence of a stimulus. To investigate neural deviance detection in the auditory cortex (AC) of anaesthetised bats (Phyllostomus discolor), we designed sequences of repetitive naturalistic virtual echoes differing in spectro-temporal envelope, resembling those bats might perceive in their natural environment. In these sequences, one echo (standard) was repeated ten times and another echo (deviant) was presented at the end. Temporal intervals between echoes within the sequences varied. Our results show, that neurons in the AC of the bat P. discolor are sensitive to novel virtual echoes presented at the end of these repetitive sequences: In 49 % (62/126) of cortical neurons, extracellularly recorded responses adapted to the standard echo, but showed a strong response to the finally presented deviant echo. This effect depended strongly on the temporal intervals between echoes, with stronger adaptation at shorter intervals. This type of response behavior might represent a form of neuronal deviance detection in the AC that could help the bats to detect echoes of novel and potentially important objects within a stream of homogeneous background echoes.

The influence of stimulus history on directional coding in the monarch butterfly brain

“…However, in nature, cues are usually not processed as discrete events in time but rather form a continuous perception of the cue. Therefore, it is not surprising that many neurons are highly sensitive to the stimulus history and integrate information from subsequent stimuli (Clark and Demb 2016 ; Weber et al 2019 ; Jin and Glickfeld 2020 ; Benda 2021 ; López-Jury et al 2021 ; Beetz and Hechavarría 2022 ; Pastyrik and Firzlaff 2022 ; Price and Gavornik 2022 ). Here, we explicitly tested how the stimulus history, i.e., angular velocity and trajectory of a compass cue, affects the directional coding in the monarch butterfly brain.…”