Inhibition dominates sensory responses in the awake cortex

Area of Science:

• Neuroscience
• Sensory Processing
• Cortical Activity

Background:

• Cortical activity relies on the balance between synaptic excitation and inhibition.
• Previous studies on visual cortex responses were conducted under anesthesia, limiting understanding of awake brain function.
• The synaptic activity during natural visual stimulation in awake states remains largely unknown.

Purpose of the Study:

• To investigate and compare visually evoked synaptic responses in the visual cortex of anesthetized and awake mice.
• To elucidate the role of synaptic excitation and inhibition in sensory processing during different cortical states.

Main Methods:

• Whole-cell patch-clamp recordings in the visual cortex of mice.
• Measurement of visually evoked responses and underlying synaptic conductances.
• Comparison of neural activity and synaptic dynamics between anesthetized and awake states.

Main Results:

• Awake mice exhibited more spatially selective and briefer visual responses compared to anesthetized mice.
• Synaptic inhibition was significantly stronger and broader in spatial selectivity during wakefulness than under anesthesia.
• Under anesthesia, inhibition mirrored excitation's amplitude and spatial selectivity.

Conclusions:

• Cortical responses to visual stimuli in the awake brain are predominantly controlled by strong, broadly selective synaptic inhibition.
• This inhibition restricts the spatial spread and temporal duration of neural activity in the visual cortex.
• The findings offer insights into the synaptic mechanisms governing sensory responses in the awake cortex.