Orientation and direction tuning align with dendritic morphology and spatial connectivity in mouse visual cortex.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Functional properties of neocortical pyramidal cells (PCs), like visual direction and orientation selectivity, are shaped by excitatory and inhibitory inputs.
• The precise relationship between L2/3 PC function, spatial information sampling, and integration remains unclear.

Purpose of the Study:

• To investigate the link between dendritic morphology, input connectivity, and the orientation/direction tuning of L2/3 PCs in the mouse visual cortex.
• To understand how spatial arrangement of inputs influences neuronal selectivity.

Main Methods:

• Combined in vivo two-photon calcium imaging, in vitro functional circuit mapping, and dendritic reconstruction of individual L2/3 PCs.
• Analyzed the spatial distribution of excitatory and inhibitory inputs relative to dendritic structure and neuronal tuning.

Main Results:

• Found correlations between apical dendritic tree elongation and preferred orientation, with less complex trees in sharply tuned cells.
• Observed spatial offset of presynaptic partners in direction-selective PCs, with excitatory inputs skewed along the preferred direction.
• Demonstrated a positive correlation between input asymmetry and the degree of direction selectivity.

Conclusions:

• Dendritic architecture and the spatial organization of presynaptic excitatory and inhibitory cells significantly shape L2/3 PC orientation and direction tuning.
• Spatial arrangement of inputs is a critical factor in determining the functional selectivity of visual cortical neurons.