Enhanced perceptual task performance without deprivation in mice using medial forebrain bundle stimulation

Training animals on perceptual decision-making tasks is essential to many fields of neuroscience. Current protocols generally use water as a reward in water-deprived animals. This can be challenging since it requires balancing animals’ deprivation level with their well-being. Moreover, trial number is limited once they reach satiation. Here, we present electrical stimulation of the medial forebrain bundle (MFB) as an alternative reward in mice that avoids deprivation entirely while yielding stable motivation for thousands of trials. We trained MFB rewarded mice to perform a series of auditory discrimination tasks using either licking or lever pressing as a behavioural report. MFB animals learnt tasks at similar speed to water-deprived mice and more reliably reached higher overall accuracy in harder tasks. Moreover, they performed up to 3800 trials within a session without loss of motivation. Importantly, MFB stimulation does not impact the sensory behaviour under study since psychometric parameters and response times are preserved. Finally, in accordance with the lack of deprivation, MFB mice lack signs of metabolic or behavioural stress compared to water-deprived mice (weight loss, open field, home cage behaviour). Overall, using MFB stimulation as a reward is a highly promising tool for task learning since it enhances task performance whilst avoiding deprivation.