Biology subjects

Okanoya, K.

Publications and source records attributed to Okanoya, K..

24 records · Page 2Linked to original sources

bioRxiv2020

CA2 inhibition reduces the precision of hippocampal assembly reactivation

The structured reactivation of hippocampal neuronal ensembles during fast synchronous oscillatory events termed sharp-wave ripples (SWRs) has been suggested to play a crucial role in the storage and use of memory. Activity in both the CA2 and CA3 subregions can proceed this population activity in CA1 and chronic inhibition of either region alters SWR oscillations. However, the precise contribution of CA2 to the oscillation, as well as to the reactivation of CA1 neurons within it, remains unclear. Here we employ chemogenetics to transiently silence CA2 pyramidal cells in mice and observe that while SWRs still occur, the reactivation of CA1 pyramidal cell ensembles within the events lose both temporal and informational precision. These observations suggest that CA2 activity contributes to the fidelity of experience-dependent hippocampal replay.

neuroscience↗

bioRxiv2020

Spontaneous variability predicts adaptive motor response in vocal pitch control

Our motor system uses sensory feedback to keep behavioral performance in desired status. From this view, motor fluctuation is not simply noise inevitably caused in the nervous system, but should provide a role in generating variations to explore better outcomes via their sensory feedback. Vocal control system offers a good model to investigate such adaptive sensory-motor interactions. The pitch, or fundamental frequency (FF), of voice is adaptively regulated by hearing its auditory feedback to compensate FF deviations. Animal studies, particularly for songbirds, have demonstrated that the variability in vocal features contributes to the adaptive control, although the same issue in human vocalizations has remained unclear. Here, we tested whether and how the motor variability contributes to adaptive control of vocal FF in humans. We measured the amount of compensatory vocal responses against FF shifts in the auditory feedback, and quantified the motor variability as amplitudes of spontaneous FF fluctuations during no shift vocalizations. The result showed a positive correlation between the ratio of compensation and the spontaneous vocal variability. Further analysis indicated that this correlation was due to slowly fluctuating components (<5 Hz) of the variability, but not fast fluctuations (6-30 Hz), which is likely to reflect controllability from the central nervous system. Moreover, the compensatory responses consisted of the same frequency range with the slow component in the spontaneous variability. These findings consistently demonstrated that the spontaneous motor variability predicts the adaptive control in vocal FF, supporting the motor exploration hypothesis. Significance statementWe regulate our own vocalization by hearing own voice. This fact is typically observed as canceling-out (compensatory) responses in vocalized pitch when artificial pitch shifts were induced in the auditory feedback of own voice. Interestingly, the amount of such compensation widely ranges among talkers from perfect cancellation to almost nothing. Here we demonstrated that participants who spontaneously exhibited larger fluctuations showed greater amounts of the compensation against feedbacked pitch shifts. Our in-depth analyses showed that slowly fluctuating components in spontaneous pitch variability are specifically correlated with the compensation ratios, and was shared in the compensatory response as a dominant component. These findings support the idea that such variability contributes to generating motor explorations to find better outcomes in motor controls.

neuroscience↗

bioRxiv2020

Measuring Long Context Dependency in Birdsong Using an Artificial Neural Network with a Long-Lasting Working Memory

Context dependency is a key feature in sequential structures of human language, which requires reference between words far apart in the produced sequence. Assessing how long the past context has an effect on the current status provides crucial information to understand the mechanism for complex sequential behaviors. Birdsongs serve as a representative model for studying the context dependency in sequential signals produced by non-human animals, while previous reports were upper-bounded by methodological limitations. Here, we newly estimated the context dependency in birdsongs in a more scalable way using a modern neural-network-based language model whose accessible context length is sufficiently long. The detected context dependency was beyond the order of traditional Markovian models of birdsong, but was consistent with previous experimental investigations. We also studied the relation between the assumed/auto-detected vocabulary size of birdsong (i.e., fine-vs. coarse-grained syllable classifications) and the context dependency. It turned out that the larger vocabulary (or the more fine-grained classification) is assumed, the shorter context dependency is detected.

animal behavior and cognition↗

bioRxiv2020

Fast retrograde access to projection neuron circuits underlying vocal learning in songbirds

Understanding the structure and function of neural circuits underlying speech and language is a vital step towards better treatments for diseases of these systems. Songbirds, among the few animal orders that share with humans the ability to learn vocalizations from a conspecific, have provided many insights into the neural mechanisms of vocal development. However, research into vocal learning circuits has been hindered by a lack of tools for rapid genetic targeting of specific neuron populations to meet the quick pace of developmental learning. Here, we present a new viral tool that enables fast and efficient retrograde access to projection neuron populations. In zebra finches, Bengalese finches, canaries, and mice, we demonstrate fast retrograde labeling of cortical or dopaminergic neurons. We further demonstrate the suitability of our construct for detailed morphological analysis, for in vivo imaging of calcium activity, and for multicolor brainbow labeling.

neuroscience↗

bioRxiv2019

USVSEG: A robust segmentation of rodents’ ultrasonic vocalization

Rodents ultrasonic vocalization (USV) provides useful information to assess their social behaviors. Despite of previous efforts for classifying subcategories of time-frequency patterns of USV syllables to associate with their functional relevances, detection of vocal elements from continuously recorded data have remained to be not well-optimized. We here propose a novel procedure for detecting USV segments in continuous sound data with background noises which were inevitably contaminated during observation of the social behavior. The proposed procedure utilizes a stable version of spectrogram and additional signal processing for better separation of vocal signals by reducing variation of the background noise. Our procedure also provides a precise time tracking of spectral peaks within each syllable. We showed that this procedure can be applied to a variety of USVs obtained from several rodent species. A performance test with an appropriate parameter set showed performance for detecting USV syllables than conventional methods.

animal behavior and cognition↗

bioRxiv2019

A language-familiarity effect on the recognition of computer-transformed vocal emotional cues

People are more accurate in voice identification and emotion recognition in their native language than in other languages, a phenomenon known as the language familiarity effect (LFE). Previous work on cross-cultural inferences of emotional prosody has left it difficult to determine whether these native-language advantages arise from a true enhancement of the auditory capacity to extract socially relevant cues in familiar speech signals or, more simply, from cultural differences in how these emotions are expressed. In order to rule out such production differences, this work employed algorithmic voice transformations to create pairs of stimuli in the French and Japanese language which differed by exactly the same amount of prosodic expression. Even though the cues were strictly identical in both languages, they were better recognized when participants processed them in their native language. This advantage persisted in three types of stimulus degradation (jabberwocky, shuffled and reversed sentences). These results provide univocal evidence that production differences are not the sole drivers of LFEs in cross-cultural emotion perception, and suggest that it is the listeners lack of familiarity with the individual speech sounds of the other language, and not e.g. with their syntax or semantics, which impairs their processing of higher-level emotional cues.

neuroscience↗