Biology subjects

Giret, N.

Publications and source records attributed to Giret, N..

7 recordsLinked to original sources

bioRxiv2025

Estimating the motor exploration in reinforcement learning

What motor exploration strategies do animals use to learn a skill from rewards? Reinforcement learning theory provides no guidance for estimating motor exploration -- the behavioral component aimed at discovering better strategies. Inspired by the brains modular organization, we postulate a latent learner that explores via an additive source of ideal randomness it injects into behavior. Assuming the learner is ignorant of other motor components, which is sub-optimal by design, evolutionary fitness argues that these should display mainly non-ideal variability. We test this recipe for behavior decomposition in songbirds subjected to a vocal pitch conditioning task. The explorative component we estimate from vocalizations accounts for the motor contribution of a basal ganglia pathway and the other behavioral component accounts for birds suboptimal learning trajectories. This congruence between normative exploration and brain organization suggests that the evolutionary pressure for behavioral optimality is lesser than to learn from purely random trials.

neuroscience↗

bioRxiv2024

Visually-guided compensation of deafening-induced song deterioration

Human language learning and maintenance depend primarily on auditory feedback but are also shaped by other sensory modalities. Individuals who become deaf after learning to speak (post-lingual deafness) experience a gradual decline in their language abilities. A similar process occurs in songbirds, where deafness leads to progressive song deterioration. However, songbirds can modify their songs using non-auditory cues, challenging the prevailing assumption that auditory feedback is essential for vocal control. In this study, we investigated whether deafened birds could use visual cues to prevent or limit song deterioration. We developed a new metric for assessing syllable deterioration called the spectrogram divergence score. We then trained deafened birds in a behavioral task where the spectrogram divergence score of a target syllable was computed in real-time, triggering a contingent visual stimulus based on the score. Birds exposed to the contingent visual stimulus--a brief light extinction--showed more stable song syllables than birds that received either no light extinction or randomly triggered light extinction. Notably, this effect was specific to the targeted syllable and did not influence other syllables. This study demonstrates that deafness-induced song deterioration in birds can be partially mitigated with visual cues.

neuroscience↗

bioRxiv2024

Neural population dynamics during sleep in a songbird vocal circuit resemble sharp wave ripple activity

Similar to motor skill learning in mammals, vocal learning in songbirds requires a set of interconnected brain areas that make up an analogous basal ganglia-thalamocortical circuit known as the anterior forebrain pathway (AFP). Although neural activity in the AFP has been extensively investigated during awake singing, very little is known about its neural activity patterns during other behavioral states. Here, we used chronically implanted Neuropixels probes to investigate spontaneous neural activity in the AFP during natural sleep and awake periods in male zebra finches. We found that during sleep, neuron populations in the pallial region LMAN (lateral magnocellular nucleus of the nidopallium) spontaneously exhibited synchronized bursts that were characterized by a negative sharp deflection in the local field potential (LFP) and a transient increase in gamma power. LMAN population bursts occurred primarily during non-rapid eye movement (NREM) sleep and were highly reminiscent of sharp-wave ripple (SWR) activity observed in rodent hippocampus. We also examined the functional connectivity within the AFP by calculating the pairwise LFP coherence. As expected, delta and theta band coherence within LMAN and Area X was higher during sleep compared to awake periods. Contrary to our expectations, we did not observe strong coherence between LMAN and Area X during sleep, suggesting that the input from LMAN into Area X is spatially restricted. Overall, these results provide the first description of spontaneous neural dynamics within the AFP across behavioral states. Significance statementAlthough cortical and basal ganglia circuits are known to be required for learning in both mammals and birds, little is known about the ongoing spontaneous activity patterns within these circuits, or how they are modulated by behavioral state. Here we prove the first description of cortical-basal ganglia network activity during sleep and awake periods in birds. Within the pallial area LMAN, we observed population-wide bursting events that were highly reminiscent of hippocampal sharp-wave ripple (SWR) activity, suggesting that large-scale population events have diverse functions across vertebrates.

neuroscience↗

bioRxiv2024

Familiarity of an environment prevents song suppression in isolated zebra finches

Despite the wide use of zebra finches as an animal model to study vocal learning and production, little is known about impacts on their welfare caused by routine experimental manipulations such as changing their social context. Here we conduct a post-hoc analysis of singing rate, an indicator of positive welfare, to gain insights into stress caused by social isolation, a common experimental manipulation. We find that isolation in an unfamiliar environment reduces singing rate for several days, indicating the presence of an acute stressor. However, we find no such decrease when social isolation is caused by either removal of a social companion or by transfer to a familiar environment. Furthermore, during repeated brief periods of isolation, singing rate remains high when isolation is induced by removal of social companions, but it fails to recover from a suppressed state when isolation is induced by recurrent transfer to an unknown environment. These findings suggest that stress from social isolation is negligible compared to stress caused by environmental changes and that frequent short visits of an unfamiliar environment are detrimental rather than beneficial. Together, these insights can serve to refine experimental studies and design paradigms maximizing the birds wellbeing and vocal output.

zoology↗

bioRxiv2022

Goal-directed vocal planning in a songbird

Songbirds vocal mastery is impressive, but to what extent is it a result of practice? Can they, based on experienced mismatch with a known target, plan the necessary changes to recover the target in a practice-free manner without intermittently singing? In adult zebra finches, we drive the pitch of a song syllable away from its stable (baseline) variant acquired from a tutor, then we withdraw reinforcement and subsequently deprive them of singing experience by muting or deafening. In this deprived state, birds do not recover their baseline song. However, they revert their songs towards the target by about one standard deviation of their recent practice, provided the sensory feedback during the latter signaled a pitch mismatch with the target. Thus, targeted vocal plasticity does not require immediate sensory experience, showing that zebra finches are capable of goal-directed vocal planning.

neuroscience↗

bioRxiv2021

Distinct timescales for the neuronal encoding of vocal signals in a high-order auditory area

The ability of the auditory system to selectively recognize natural sound categories with a tolerance to variations within categories is thought to be crucial for vocal communication. Subtle variations, however, may have functional roles. To date, how the coding of the balance between tolerance and sensitivity to variations in acoustic signals is performed at the neuronal level requires further studies. We investigated whether neurons of a high-order auditory area in a songbird species, the zebra finch, are sensitive to natural variations in vocal signals by recording responses to repeated exposure to similar and variant sound sequences. We took advantage of the intensive repetition of the male songs which subtly vary from rendition to rendition. In both anesthetized and awake birds, responses based on firing rate during sequence presentation did not show any clear sensitivity to these variations, unlike the temporal reliability of responses based on a 10 milliseconds resolution that depended on whether variant or similar sequences were broadcasted and the context of presentation. Results therefore suggest that auditory processing operates on distinct timescales, a short one to detect variations in individuals vocal signals, longer ones that allow tolerance in vocal signal structure and the encoding of the global context.

neuroscience↗

bioRxiv2019

Sensory substitution reveals a manipulation bias

Sensory substitution is a promising therapeutic approach for replacing a missing or diseased sensory organ by translating inaccessible information into another sensory modality. What aspects of substitution are important such that subjects accept an artificial sense and that it benefits their voluntary action repertoire? To obtain an evolutionary perspective on affective valence implied in sensory substitution, we introduce an animal model of deaf songbirds. As a substitute of auditory feedback, we provide binary visual feedback. Deaf birds respond appetitively to song-contingent visual stimuli, they skillfully adapt their songs to increase the rate of visual stimuli, showing that auditory feedback is not required for making targeted changes to a vocal repertoire. We find that visually instructed song learning is basal-ganglia dependent. Because hearing birds respond aversively to the same visual stimuli, sensory substitution reveals a bias for actions that elicit feedback to meet animals manipulation drive, which has implications beyond rehabilitation.

neuroscience↗