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Positive reinforcement helps to control the acquisition of learned behaviours. Here we report a cellular mechanism in the brain that may underlie the behavioural effects of positive reinforcement. We used intracranial self-stimulation (ICSS) as a model of reinforcement learning, in which each rat learns to press a lever that applies reinforcing electrical(More)
There is a large body of data on the firing properties of dopamine cells in anaesthetised rats or rat brain slices. However, the extent to which these data relate to more natural conditions is uncertain, as there is little quantitative information available on the firing properties of these cells in freely moving rats. We examined this by recording from the(More)
Behavioral conditioning of cue-reward pairing results in a shift of midbrain dopamine (DA) cell activity from responding to the reward to responding to the predictive cue. However, the precise time course and mechanism underlying this shift remain unclear. Here, we report a combined single-unit recording and temporal difference (TD) modeling approach to(More)
Midbrain dopamine (DA) neurons respond to sensory cues that predict reward. We tested the hypothesis that projections from the pedunculopontine tegmental nucleus (PPTg) are involved in driving this DA cell activity. First, the activity of PPTg and DA neurons was compared in a cued-reward associative learning paradigm. The majority of PPTg neurons showed(More)
High-frequency stimulation of around 130 Hz delivered to the subthalamic nucleus (STN-DBS [deep brain stimulation]) is an effective treatment of Parkinson's disease (PD), but the mechanisms of its therapeutic effect remain obscure. Recently, it has been shown in anaesthetized rats that STN-DBS antidromically activates cortical neurons with coincident(More)
Striatal cholinergic interneurons, also known as tonically active neurons (TANs), acquire a pause in firing during learning of stimulus-reward associations. This pause response to a sensory stimulus emerges after repeated pairing with a reward. The conditioned pause is dependent on dopamine from the substantia nigra, but its underlying cellular mechanism is(More)
The dorsal raphe nucleus (DRN) is implicated in mood regulation, control of impulsive behavior, and in processing aversive and reward-related signals. DRN neurons show phasic responses to sensory stimuli, but whether association with reward modulates these responses is unknown. We recorded DRN neurons from rats in a contextual conditioned approach paradigm(More)
The striatum is the major input nucleus of the basal ganglia. It is thought to play a key role in learning on the basis of positive reinforcement and in action selection. One view of the striatum conceives it as comprising a reiterated matrix of processing units that perform common operations in different striatal regions, namely synaptic plasticity(More)
A chronic single-unit study of motor cortical activity was undertaken in two monkeys trained to perform a bimanually coordinated task. The hypothesis was tested that the supplementary motor area plays a specific role in coordinating the two hands for common goal-oriented actions. With this objective, a special search was made for neurons that might exhibit(More)
Neuronal activity recorded from the primary motor cortex (MI) and from the supplementary motor area (SMA) was compared in two monkeys trained to perform conditioned arm movements. A handle had to be held in a central waiting position until a visual go and cueing signal indicated to the monkey to move the handle either to a medial or to a lateral target zone(More)