PT  - JOURNAL ARTICLE
AU  - Alessandro R. Galloni
AU  - Zhiwen Ye
AU  - Ede Rancz
TI  - Dendritic domain-specific sampling of long-range axons shapes feedforward and feedback connectivity of L5 neurons
AID  - 10.1101/2021.01.31.429033
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.01.31.429033
4099  - http://biorxiv.org/content/early/2021/08/02/2021.01.31.429033.short
4100  - http://biorxiv.org/content/early/2021/08/02/2021.01.31.429033.full
AB  - Feedforward and feedback pathways interact in specific dendritic domains to enable cognitive functions such as predictive processing and learning. Based on axonal projections, hierarchically lower areas are thought to form synapses primarily on dendrites in middle cortical layers, while higher-order areas are posited to target dendrites in layer 1 and in deep layers. However, the extent to which functional synapses form in regions of axo-dendritic overlap has not been extensively studied. Here, we use viral tracing in the secondary visual cortex of mice to map brain-wide inputs to thick-tufted layer 5 pyramidal neurons. Furthermore, we provide a comprehensive map of input locations through subcellular optogenetic circuit mapping. We show that input pathways target distinct dendritic domains with far greater specificity than appears from their axonal branching, often deviating substantially from the canonical patterns. Common assumptions regarding the dendrite-level interaction of feedforward and feedback inputs may thus need revisiting.Competing Interest StatementThe authors have declared no competing interest.