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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)
The spiny projection neurons are by far the most numerous type of striatal neuron. In addition to being the principal projection neurons of the striatum, the spiny projection neurons also have an extensive network of local axon collaterals by which they make synaptic connections with other striatal projection neurons. However, up to now there has been no(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)
Knowledge of the effect of dopamine on corticostriatal synaptic plasticity has advanced rapidly over the last 5 years. We consider this new knowledge in relation to three factors proposed earlier to describe the rules for synaptic plasticity in the corticostriatal pathway. These factors are a phasic increase in dopamine release, presynaptic activity and(More)
Learning deficits resulting from dopamine depletion suggest that striatal dopamine release is crucial for reinforcement. Recently described firing patterns of dopamine neurons in behaving monkeys show that transient increases in dopamine release are brought about by reinforcement. We describe an enduring change in the strength of synaptic transmission(More)
The striatum is composed of GABAergic medium spiny neurons with inhibitory collaterals forming a sparse random asymmetric network and receiving an excitatory glutamatergic cortical projection. Because the inhibitory collaterals are sparse and weak, their role in striatal network dynamics is puzzling. However, here we show by simulation of a striatal(More)
The spiny projection neurons of the neostriatum are a site at which dopamine inputs from the substantia nigra converge with excitatory inputs from the cerebral cortex. These two systems interact in certain learning and motor control mechanisms of the brain. We investigated these interactions using intracellular recording from spiny striatal neurons in(More)
This review considers the hypothesis that changes in dopamine signalling might account for altered sensitivity to positive reinforcement in children with ADHD. The existing evidence regarding dopamine cell activity in relation to positive reinforcement is reviewed. We focus on the anticipatory firing of dopamine cells brought about by a transfer of dopamine(More)
Both silent and spontaneously firing spiny projection neurons have been described in the neostriatum, but the reason for their differences in firing activity are unknown. We compared properties of spontaneously firing and silent spiny neurons in urethan-anesthetized rats. Neurons were identified as spiny projection neurons after labeling by intracellular(More)
In recent years, dopamine has emerged as a key neurotransmitter that is crucially involved in incentive motivation and reinforcement learning. Dopamine release is evoked by rewards. The extensive divergence of outputs from a small number of dopaminergic neurons suggests a spatially nonselective action of dopamine, but it reinforces the specific actions that(More)