AUTHOR=Hovde Karoline , Rautio Ida V. , Hegstad Andrea M. , Witter Menno P. , Whitlock Jonathan R. 

TITLE=Visuomotor interactions in the mouse forebrain mediated by extrastriate cortico-cortical pathways

JOURNAL=Frontiers in Neuroanatomy

VOLUME=Volume 17 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2023.1188808

DOI=10.3389/fnana.2023.1188808

ISSN=1662-5129

ABSTRACT=The mammalian visual system can be broadly divided into two functional processing pathways: a dorsal stream supporting visually and spatially guided actions, and a ventral stream enabling object recognition. In rodents, the majority of visual signaling in the dorsal stream is transmitted to frontal motor cortices via extrastriate visual areas surrounding V1, but exactly where and to what extent V1 feeds into motor-projecting visual regions is not well known. To address this we employed a dual labeling strategy in male and female mice in which efferent projections from V1 were labeled anterogradely, and motor-projecting neurons in higher visual areas were labeled with retrogradely traveling adeno-associated virus (rAAV-retro) injected in M2. In flattened sections of dorsal cortex, the most pronounced colocalization V1 output and M2 input occurred in extrastriate areas AM, PM, RL and AL. Coronal sections further showed that neurons in both superficial and deep layers in these regions project to M2, but high resolution volumetric reconstructions revealed that the vast majority of putative synaptic contacts from V1 onto M2-projecting neurons occurred in layer 2/3. These findings support the existence of a dorsal processing stream in the mouse visual system, where visual signals reach motor cortex largely via feedforward projections in anteriorly and medially located extrastriate areas.