Development of Activity in the Mouse Visual Cortex

Area of Science:

• Neuroscience
• Developmental Biology
• Computational Neuroscience

Background:

• Cortical activity is crucial for brain development and health, yet its maturation process in the developing cortex is not fully understood.
• Gaps exist in knowledge regarding the origin and progression of cortical activity, particularly in preclinical models relevant to human development.

Purpose of the Study:

• To systematically track spontaneous and sensory-evoked cortical activity in the primary visual cortex (V1) of developing mice.
• To establish a comprehensive developmental timeline of cortical activity maturation in vivo.
• To identify critical checkpoints and key principles governing cortical circuit development.

Main Methods:

• Extracellular recordings were performed in the primary visual cortex (V1) of nonanesthetized mice across postnatal development.
• Daily changes in spontaneous and sensory-evoked electrical activity were monitored.
• Activity patterns, including network silence, slow-activity transients, spindle-burst oscillations, and mature asynchronous/synchronous states, were analyzed.

Main Results:

• Early V1 activity (P4-P7) consisted of network silence punctuated by slow-activity transients (spindle-burst oscillations).
• Maturation involved spindle-burst frequency acceleration and the "filling-in" of silent periods with low-frequency activity by P13.
• Emergent visual responses (P8) with high signal-to-noise ratios were transient, disappearing by eye opening.

Conclusions:

• The study delineates the developmental trajectory of cortical electrical activity, from early silence to adult patterns.
• The period before eye opening is identified as a critical checkpoint for cortical development.
• The murine visual cortex serves as a valuable model for studying human fetal electroencephalographic development.