RT Journal Article
SR Electronic
T1 A direct interareal feedback-to-feedforward circuit in primate visual cortex
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.07.07.192450
DO 10.1101/2020.07.07.192450
A1 Caitlin Siu
A1 Justin Balsor
A1 Sam Merlin
A1 Frederick Federer
A1 Alessandra Angelucci
YR 2021
UL http://biorxiv.org/content/early/2021/01/15/2020.07.07.192450.abstract
AB The mammalian sensory neocortex consists of hierarchically organized areas reciprocally connected via feedforward (FF) and feedback (FB) circuits. Several theories of hierarchical computation ascribe the bulk of the computational work of the cortex to looped FF-FB circuits between pairs of cortical areas. However, whether such corticocortical loops exist remains unclear. In higher mammals, individual FF-projection neurons send afferents almost exclusively to a single higher-level area. However, it is unclear whether FB-projection neurons show similar area specificity, and whether they influence FF-projection neurons directly or indirectly. Using viral-mediated monosynaptic circuit tracing in macaque primary visual cortex (V1), we show that V1 neurons sending FF projections to area V2 receive monosynaptic FB inputs from V2, but not other V1-projecting areas. We also find monosynaptic FB-to-FB neuron contacts as a second motif of FB connectivity. Our results support the existence of FF-FB loops in primate cortex, and suggest that FB can rapidly and selectively influence the activity of incoming FF signals.Competing Interest StatementThe authors have declared no competing interest.