Biology subjects

Martin, J.-R.

Publications and source records attributed to Martin, J.-R..

4 recordsLinked to original sources

bioRxiv2019

Does nonlinear neural network dynamics explain human confidence in a sequence of perceptual decisions ?

Electrophysiological recordings during perceptual decision tasks in monkeys suggest that the degree of confidence in a decision is based on a simple neural signal produced by the neural decision process. Attractor neural networks provide an appropriate biophysical modeling framework, and account for the experimental results very well. However, it remains unclear whether attractor neural networks can account for confidence reports in humans. We present the results from an experiment in which participants are asked to perform an orientation discrimination task, followed by a confidence judgment. Here we show that an attractor neural network model quantitatively reproduces, for each participant, the relations between accuracy, response times and confidence. We show that the attractor neural network also accounts for confidence-specific sequential effects observed in the experiment (participants are faster on trials following high confidence trials). Remarkably, this is obtained as an inevitable outcome of the network dynamics, without any feedback specific to the previous decision (that would result in, e.g., a change in the model parameters before the onset of the next trial). Our results thus suggest that a metacognitive process such as confidence in ones decision is linked to the intrinsically nonlinear dynamics of the decision-making neural network.

neuroscience↗

bioRxiv2019

Comparing self- and hetero-metacognition in the absence of verbal communication

The ability to infer how confident other people are in their decisions is crucial for regulating social interactions. It is unclear whether one can read others confidence in absence of verbal communication and whether one can infer it as accurately as for ones own confidence. To address these questions, we used an auditory task in which participants had to guess the confidence of someone else performing the task or to judge their own confidence in different conditions (i.e., while performing the task themselves or while watching themselves performing the task on a pre-recorded video). Results show that participants are able to guess the confidence of other people as accurately as when judging their own. Crucially, we show that hetero-metacognition is a flexible mechanism relying on different cues according to the context. Our results support the idea that metacognition leverages the same inference mechanisms as involved in theory of mind.

neuroscience↗

bioRxiv2018

jouvence, a new small nucleolar RNA required in the gut extends lifespan in Drosophila

Longevity is influenced by various genetic and environmental factors, but the underlying mechanisms remain poorly understood. Here, we functionally characterise a new Drosophila small nucleolar RNA (snoRNA), named jouvence whose loss of function dramatically reduces lifespan. A transgene containing the genomic region of jouvence rescues the longevity in mutant, while its overexpression in wild-type flies increases lifespan. Jouvence is expressed in epithelial cells of the gut. Targeted expression of jouvence specifically in the enterocytes increases lifespan, indicating that its role in the control of longevity takes place in these cells. A transcriptomic analysis performed from the gut reveals that several genes are either up-or down-regulated in mutant indicating that the snoRNA-jouvence might be involved in transcriptional control. Finally, since snoRNAs are structurally and functionally well conserved throughout evolution, we identified putative jouvence orthologue in mammals including humans, suggesting that its function in longevity might be conserved through evolution.

genetics↗

bioRxiv2017

A lineage-related reciprocal inhibition circuitry for sensory-motor action selection

The insect central complex and vertebrate basal ganglia are forebrain centres involved in selection and maintenance of behavioural actions. However, little is known about the formation of the underlying circuits, or how they integrate sensory information for motor actions. Here, we show that paired embryonic neuroblasts generate central complex ring neurons that mediate sensory-motor transformation and action selection in Drosophila. Lineage analysis resolves four ring neuron subtypes, R1-R4, that form GABAergic inhibition circuitry among inhibitory sister cells. Genetic manipulations, together with functional imaging, demonstrate subtype-specific R neurons mediate the selection and maintenance of behavioural activity. A computational model substantiates genetic and behavioural observations suggesting that R neuron circuitry functions as salience detector using competitive inhibition to amplify, maintain or switch between activity states. The resultant gating mechanism translates facilitation, inhibition and disinhibition of behavioural activity as R neuron functions into selection of motor actions and their organisation into action sequences.

neuroscience↗