First Author | Issa LK | Year | 2023 |
Journal | Cereb Cortex | Volume | 33 |
Issue | 16 | Pages | 9566-9582 |
PubMed ID | 37386697 | Mgi Jnum | J:351360 |
Mgi Id | MGI:7663233 | Doi | 10.1093/cercor/bhad227 |
Citation | Issa LK, et al. (2023) Highly branched and complementary distributions of layer 5 and layer 6 auditory corticofugal axons in mouse. Cereb Cortex 33(16):9566-9582 |
abstractText | The auditory cortex exerts a powerful, yet heterogeneous, effect on subcortical targets. Auditory corticofugal projections emanate from layers 5 and 6 and have complementary physiological properties. While several studies suggested that layer 5 corticofugal projections branch widely, others suggested that multiple independent projections exist. Less is known about layer 6; no studies have examined whether the various layer 6 corticofugal projections are independent. Therefore, we examined branching patterns of layers 5 and 6 auditory corticofugal neurons, using the corticocollicular system as an index, using traditional and novel approaches. We confirmed that dual retrograde injections into the mouse inferior colliculus and auditory thalamus co-labeled subpopulations of layers 5 and 6 auditory cortex neurons. We then used an intersectional approach to relabel layer 5 or 6 corticocollicular somata and found that both layers sent extensive branches to multiple subcortical structures. Using a novel approach to separately label layers 5 and 6 axons in individual mice, we found that layers 5 and 6 terminal distributions partially spatially overlapped and that giant terminals were only found in layer 5-derived axons. Overall, the high degree of branching and complementarity in layers 5 and 6 axonal distributions suggest that corticofugal projections should be considered as 2 widespread systems, rather than collections of individual projections. |