The subcortical visual pathway through the midbrain superior colliculus is responsible for visually evoked Pavlovian conditioning and dopamine neuron responses with predicted value in monkeys, which remained after lesioning V1.
Although the phasic activity of midbrain dopamine neurons is known to represent reward values, these neurons displayed a tonic firing mode to continuously track reward values changing moment-by-moment.
Dopamine neurons projecting to different targets receive a similar set of inputs, rather than forming reciprocal connections, whereas those projecting to the posterior striatum receive a distinct set of inputs.
Dopamine neurons signal value prediction errors (VPEs) integrating information about both reward and aversion, in low reward contexts, whereas VPEs in some dopamine neurons are distorted in high reward contexts.
The conditional reduction of glutaminase in mouse dopamine neurons selectively attenuates glutamate cotransmission at phasic frequencies, revealing the role of dopamine neuron glutamate cotransmission in the attribution of motivational salience.