Three Types of Cortical Layer 5 Neurons That Differ in Brain-wide Connectivity and Function

Area of Science:

• Neuroscience
• Visual Cortex Research
• Cellular Neuroscience

Background:

• Cortical layer 5 (L5) pyramidal neurons are crucial for integrating and distributing information.
• Two previously identified L5 neuron types are cortico-cortical (CC) and cortico-subcortical (CS).

Purpose of the Study:

• To characterize the connectivity and function of L5 pyramidal neuron subtypes in the mouse primary visual cortex.
• To identify and describe any novel L5 neuron subtypes.

Main Methods:

• Monosynaptic rabies tracing to map neuronal connectivity.
• Electrophysiological recordings to assess neuronal physiology.
• Analysis of visual response properties.

Main Results:

• A new L5 neuron subtype, cortico-cortical non-striatal (CC-NS), was identified with distinct morphology and physiology.
• CC neurons preferentially receive input from higher visual areas.
• CS neurons receive more input from brain regions involved in top-down modulation and exhibit greater direction selectivity and preference for faster stimuli.

Conclusions:

• Distinct L5 pyramidal neuron subtypes (CC, CS, and CC-NS) serve specialized roles in visual processing.
• CS neurons are involved in integrating information for movement control.
• CC neurons are more critical for visual perception.