Biology subjects

Toutounji, H.

Publications and source records attributed to Toutounji, H..

3 recordsLinked to original sources

bioRxiv2022

Species-conserved mechanisms of cognitive flexibility in complex environments

Rapid learning in complex and changing environments is a hallmark of intelligent behavior. Humans achieve this in part through abstract concepts applicable to multiple, related situations. It is unclear, however, whether some of the underlying computational mechanisms also exist in other species. We combined behavioral, computational and electrophysiological analyses of a multidimensional rule-learning paradigm in rats and humans. We report that both species infer task rules by sequentially testing different hypotheses, rather than learning the correct action for all possible combinations of task-related cues. Neural substrates of hypothetical rules were detected in prefrontal network activity of both species. This species-conserved mechanism reduces task dimensionality and explains key experimental observations: sudden behavioral transitions and facilitated learning after prior experience. Our findings open the black box of hypothesis testing in rodents and provide a foundation for the translational investigation of impaired cognitive flexibility.

neuroscience↗

bioRxiv2022

Learning the action inventory of a complex skill via an intrinsic reward

Reinforcement learning (RL) is thought to underlie the acquisition of vocal skills like birdsong and speech, where sounding like ones "tutor" is rewarding. Yet, we find that the standard actor-critic RL model of birdsong learning fails to account for juvenile zebra finches efficient learning of an inventory of multiple syllables. But when we replace a single actor with multiple independent actors that jointly maximize a common intrinsic reward, then birds empirical learning trajectories are accurately reproduced. Importantly, the influence of each actor (syllable) on the magnitude of global reward is competitively determined by its acoustic similarity to target syllables. This leads to each actor matching the target it is closest to, and occasionally, to the competitive exclusion of an actor from the learning process (i.e., the learned song). We propose that a competitive-cooperative multi-actor (MARL) algorithm is key for the efficient learning of the action inventory of a complex skill.

animal behavior and cognition↗

bioRxiv2020

Coordinated prefrontal state transition leads extinction of reward-seeking behaviors

Extinction learning suppresses conditioned reward responses and is thus fundamental to adapt to changing environmental demands and to control excessive reward seeking. The medial prefrontal cortex (mPFC) monitors and controls conditioned reward responses. Using in vivo multiple single-unit recordings of mPFC we studied the relationship between single-unit and population dynamics during different phases of an operant conditioning task. To examine the fine temporal relation between neural activity and behavior, we developed a model-based statistical analysis that captured behavioral idiosyncrasies. We found that single-unit responses to conditioned stimuli changed throughout the course of a session even under stable experimental conditions and consistent behavior. However, when behavioral responses to task contingencies had to be updated during the extinction phase, unit-specific modulations became coordinated across the whole population, pushing the network into a new stable attractor state. These results show that extinction learning is not associated with suppressed mPFC responses to conditioned stimuli, but is driven by single-unit coordination into population-wide transitions of the animals internal state.

neuroscience↗