Optogenetic Stimulation of Midbrain Dopamine Neurons Produces Striatal Serotonin Release.

Targeting neurons with light-driven opsins is widely used to investigate cell-specific responses. We transfected midbrain dopamine neurons with the excitatory opsin Chrimson. Extracellular basal and stimulated neurotransmitter levels in the dorsal striatum were measured by microdialysis in awake mice.

Moving bar of light evokes vectorial spatial selectivity in the immobile rat hippocampus.

Visual cortical neurons encode the position and motion direction of specific stimuli retrospectively, without any locomotion or task demand. The hippocampus, which is a part of the visual system, is hypothesized to require self-motion or a cognitive task to generate allocentric spatial selectivity that is scalar, abstract and prospective. Here we measured rodent hippocampal selectivity to a moving bar of light in a body-fixed rat to bridge these seeming disparities.

Temporally restricted dopaminergic control of reward-conditioned movements.

Midbrain dopamine (DA) neurons encode both reward- and movement-related events and are implicated in disorders of reward processing as well as movement. Consequently, disentangling the contribution of DA neurons in reinforcing versus generating movements is challenging and has led to lasting controversy. In this study, we dissociated these functions by parametrically varying the timing of optogenetic manipulations in a Pavlovian conditioning task and examining the influence on anticipatory licking before reward delivery.

Interneurons Tap the Brakes on Learning.

Little was previously known about the behavioral role of low-threshold spiking interneurons in the striatum. In this issue of Neuron, Holly et al. (2019) show that their activity can slow the acquisition of novel action-outcome associations.

Hyperactivity with Disrupted Attention by Activation of an Astrocyte Synaptogenic Cue.

Hyperactivity and disturbances of attention are common behavioral disorders whose underlying cellular and neural circuit causes are not understood. We report the discovery that striatal astrocytes drive such phenotypes through a hitherto unknown synaptic mechanism. We found that striatal medium spiny neurons (MSNs) triggered astrocyte signaling via γ-aminobutyric acid B (GABA) receptors.