A non-canonical visual cortical-entorhinal pathway contributes to spatial navigation.

Area of Science:

• Neuroscience
• Visual Processing
• Spatial Cognition

Background:

• The medial entorhinal cortex (MEC) is vital for spatial cognition and memory, receiving sensory input.
• The precise routes of visual information into the MEC remain incompletely understood.
• The MEC contains spatially tuned cells and relays information to the hippocampus.

Purpose of the Study:

• To identify the specific pathways through which visual information reaches the medial entorhinal cortex (MEC).
• To elucidate the role of these visual pathways in spatial coding and navigation.
• To investigate the function of medial entorhinal cortex layer 5a (L5a) in processing visual information.

Main Methods:

• Tracing neuronal connections from the secondary visual cortex (V2) to the MEC.
• Electrophysiological recordings in the MEC to assess neural activity in response to visual stimuli.
• Behavioral experiments in mice to evaluate navigation performance after pathway interruption.

Main Results:

• A direct pathway from V2 to MEC layer 5a (L5a) was identified.
• MEC L5a neurons act as a hub, integrating visual inputs from V2 and projecting to other MEC neurons and hippocampal CA1.
• Disruption of this V2-MEC L5a pathway impaired visual-evoked activity in the MEC and navigation task performance.

Conclusions:

• A novel visual cortical-entorhinal pathway originating in V2 and targeting MEC L5a has been discovered.
• MEC L5a plays a critical role in routing visual information, challenging previous notions of sensory input primarily via superficial MEC layers.
• This pathway is essential for visual processing within the MEC and subsequent spatial navigation.