Biology subjects

Gonzalez Palomares, E.

Publications and source records attributed to Gonzalez Palomares, E..

2 recordsLinked to original sources

bioRxiv2025

Responses to oddball communication sequences in the bat frontal and auditory cortices

Stimulus-specific adaptation (SSA) is a ubiquitous phenomenon in the animal kingdom across sensory modalities, but this type of neural response has rarely been studied using natural sounds in the auditory brain. Here, we leveraged the well-documented acoustic repertoire of the bat species Carollia perspicillata to study adaptation in the bat brain using natural communication sounds. We searched for SSA in single neuron spiking activity measured in two brain areas simultaneously: the auditory cortex and the frontal auditory field. The stimuli consisted of natural distress syllables, a form of vocalization produced by bats under duress. Bat distress vocalizations signal different degrees of urgency based on their amplitude modulation pattern, without large differences in their spectral structure. These distress vocalizations make an ideal test case for exploring the limits of neural deviance detection when considering naturalistic soundscapes with low stimulus contrast. The results show limited evidence for stimulus-specific adaptation in response to natural sound sequences in the majority of neurons studied. Many neurons did show a prominent effect related to context-dependent changes, caused by the type of sounds that occurred most frequently within each oddball sequence. Context-dependent responses were strongest in frontal neurons. Decoding analysis showed the existence of neural populations in both frontal and auditory cortices, which could distinguish between deviants and standards occurring within the same sequence, without large changes in evoked spike counts. Taken together, our results highlight the diversity of neural mechanisms complementing classical stimulus-specific adaptation when encoding natural vocalizations that do not differ markedly in their spectral composition.

neuroscience↗

bioRxiv2022

A neuron model with unbalanced synaptic weights explains asymmetric effects of ketamine in auditory cortex

Although new advances in neuroscience allow the study of vocal communication in awake animals, substantial progress in the processing of vocalizations has been made from brains of anaesthetized preparations. Thus, understanding how anaesthetics affect neuronal responses is of paramount importance. Here, we used electrophysiological recordings and computational modelling to study how the auditory cortex of bats responds to vocalizations under anaesthesia and in wakefulness. We found that multifunctional neurons that process echolocation and communication sounds were affected by ketamine anaesthesia in a manner that could not be predicted by known anaesthetic effects. In wakefulness, acoustic contexts (preceding echolocation or communication sequences) led to stimulus-specific suppression of lagging sounds, accentuating neuronal responses to sound transitions. However, under anaesthesia, communication contexts (but not echolocation) led to a global suppression of responses to lagging sounds. Such asymmetric effect was dependent on the frequency composition of the contexts and not on their temporal patterns. We constructed a neuron model that could replicate the data obtained in vivo. In the model, anaesthesia modulates spiking activity in a channel-specific manner, decreasing responses of cortical inputs tuned to high-frequency sounds and increasing adaptation in the respective cortical synapses. Combined, our findings obtained in vivo and in silico reveal that ketamine anaesthesia does not reduce uniformly the neurons responsiveness to low and high frequency sounds. This effect depends on combined mechanisms that unbalance cortical inputs and ultimately affect how auditory cortex neurons respond to natural sounds in anaesthetized preparations.

neuroscience↗