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Authors & Affiliations
Bálint Király, Annamária Benke, Vivien Pillár, Franciska Benyó, Írisz Szabó, Balázs Hangya
Abstract
Neuromodulatory systems, more specifically dopamine, noradrenaline, serotonin, and acetylcholine can dynamically change brain states and rapidly alter information processing of large number of neurons. Therefore, they can play a crucial role in cognitive functions, including learning and memory, and are accordingly severely implicated in neurodegenerative diseases. Interestingly, neuromodulatory systems often regulate seemingly overlapping cognitive processes and show similar modes of action. To reveal possible synergistic or antagonistic relations and to better understand the exact role of these systems, we simultaneously monitored pairs of neuromodulatory systems using fiber photometry and electrophysiology techniques in mice performing a series of behavioral tasks focusing on different learning mechanisms such as psychometric operant learning and implicit statistical learning. Therefore, we designed three novel learning tasks, an auditory operant conditioning task, a gambling bandit task and a sequential serial reaction time task. In the examined subcortical target areas (the ventral striatum and the basolateral amygdala), we observed robust event related release of neuromodulators, linked to behavioral feedback and outcome predictions, which closely resembled the activity of the deep brain neuronal source of the corresponding neuromodulators. On the other hand, neuromodulator release in the prefrontal cortex was more characterized by an oscillatory alteration of neuromodulator release (demonstrated by autocorrelation analyses) but also in a task-dependent manner, entrained by behaviorally salient events. Cross-correlation analyses revealed a correlated activity between acetylcholine and dopamine in all examined brain areas, which scaled with reward prediction error across all learning mechanisms, while a negative correlation was observed between acetylcholine and serotonin release.