Biology subjects

Hegedüs, P.

Publications and source records attributed to Hegedüs, P..

3 recordsLinked to original sources

bioRxiv2026

Cholinergic--dopaminergic interplay underlies prediction error broadcasting

Neuromodulatory systems, notably basal forebrain cholinergic and midbrain dopaminergic pathways, critically influence reinforcement learning 1-3. However, whether and how they cooperate or compete to jointly control associative learning functions remains unresolved. Here we demonstrate that basal forebrain cholinergic and midbrain dopaminergic projection systems form a coordinated and cross-regulating architecture for encoding prediction errors. Using dual-cell-type optogenetic tagging and real-time neurotransmitter measurements in mice performing a psychometric operant learning task, we simultaneously monitored cholinergic and dopaminergic activity during learning. Dopamine and acetylcholine jointly encoded reward prediction errors synergistically following reward and reward-predicting stimuli. In contrast, aversive outcomes elicited opposite responses in cholinergic neurons and approximately half of dopaminergic neurons. Activity in these two populations exhibited negative trial-by-trial correlations, revealing antagonistic dynamics. Consistently, channelrhodopsin-assisted circuit mapping uncovered a disynaptic inhibitory pathway from cholinergic to dopaminergic neurons. Chemogenetic suppression of cholinergic activity disrupted dopaminergic prediction error signaling, reduced punishment-induced suppression of dopamine release, and impaired learning. These results demonstrate that prediction error signaling is jointly implemented by coordinated interactions between major neuromodulatory systems, challenging the prevailing view of their functional independence and revealing coordinated cross-system interactions as an organizing principle of reinforcement learning, with implications for neuropsychiatric disease 4-6.

neuroscience↗

bioRxiv2022

Cholinergic neuronal responses to probabilistic outcome-predicting stimuli follow a weighed, unsigned prediction error model and anticipate behavioral responses

Basal forebrain cholinergic neurons (BFCNs) play an important role in associative learning, suggesting that BFCNs may participate in processing sensory stimuli that predict future outcomes. However, little is known about how BFCNs respond to outcome-predictive sensory cues and the impact of outcome probabilities on BFCN responses has not been explored. Therefore, we performed bulk calcium imaging and recorded spiking output of identified cholinergic neurons from the basal forebrain of mice performing a probabilistic Pavlovian cued outcome task that allowed us to control the predictive strength of cue stimuli. BFCNs responded strongly to sensory cues predicting likely reward, while little response was observed for cues that were rarely paired with reward. Reward delivery led to the activation of BFCNs, with less expected rewards eliciting a stronger response, while air puff punishments also evoked positive-going responses from BFCNs. We propose that BFCNs differentially weigh predictions of positive and negative reinforcement, reflecting divergent relative salience of forecasting appetitive and aversive outcomes, in accordance with a simple reinforcement learning model of a weighed, unsigned prediction error. Finally, the extent of cholinergic activation after cue stimuli predicted subsequent decision speed, suggesting that the expectation-gated cholinergic firing is instructive to reward-seeking behaviors.

neuroscience↗

bioRxiv2020

Basal forebrain-derived acetylcholine encodes valence-free reinforcement prediction error.

Acetylcholine (Ach) is released by the cholinergic basal forebrain (CBF) throughout the cortical mantle and is implicated in behavioral functions ranging from arousal to attention to learning. Yet what signal ACh provides to cortex remains unresolved, hindering our understanding of its functional roles. Here we demonstrate that the CBF signals unsigned reinforcement prediction error, in contrast to dopamine (DA) neurons that encode reward prediction error. We show that both CBF neuronal activity and acetylcholine (ACh) release at cortical targets signal reinforcement delivery, acquire responses to predictive stimuli and show diminished responses to expected outcomes, hallmarks of a prediction error. To compare ACh with DA, we simultaneously monitored the activity of both neuromodulators during a serial reversal learning task. ACh tracked learning as swiftly as DA during acquisition but lagged slightly during extinction, suggesting that these neuromodulators play complementary roles in reinforcement as their patterns of innervation, cellular targets, and signaling mechanisms are themselves complementary. Through retrograde viral tracing we show that the cholinergic and dopaminergic systems engage overlapping upstream circuits, accounting for their coordination during learning. This predictive and valence-free signal explains how ACh can proactively and retroactively improve the processing of behaviorally important stimuli, be they good or bad.

neuroscience↗