Barcoded rabies virus tracing combined with single-cell RNAseq and in situ sequencing achieves high-throughput retrograde projection mapping and synaptic connectivity mapping at cellular resolution.

Under typical monosynaptic rabies tracing conditions about 40% of first-order presynaptic synapses to cortical neurons are labeled and spread efficiency does not vary depending on the distance of synapses to the cell body, across dendrite types, or starter neuron types.

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.

Retrograde tracing of the neural circuits that control movement of the jaw and tongue reveals how shared premotor neurons help to ensure coordinated muscle activity.

Whole-brain mapping of the basal forebrain circuits reveals a connection diagram with highly convergent inputs and divergent outputs.

A novel connection from ventral striatum to motor cortex enables emotion and motivation to influence action and motor control.

Inhibitory cerebellar feedback to the inferior olive is central to computational models of learning, but novel targets of these neurons identified here expand their potential roles.

Multiple trans-synaptic tracing methods reveal that there is no spatial segregation between flexor and extensor premotor interneurons in the lumbar spinal cord.

Oligodendrocyte precursor cells receive brain-wide, circuit-specific intracortical, coritcocortical and thalamocortical synaptic inputs.

Single-cell transcriptional profiling reveals distinct neuronal subtypes of the lateral habenula differentially target downstream neuronal subtypes in the ventral tegmental area and dorsal raphe nucleus.