Synchrony timescales underlie irregular neocortical spiking

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Cortical neurons exhibit diverse spiking patterns, a key feature of brain function.
• Understanding the sources of neuronal spiking variability is crucial for deciphering neural computation.

Purpose of the Study:

• To investigate the hypothesis that cortical synchrony is the primary driver of spiking variability in vivo.
• To differentiate the contributions of intrinsic neuronal properties versus network drive to spiking variability.

Main Methods:

• Utilized dynamic clamp techniques to manipulate neuronal properties in vitro.
• Employed large-scale electrophysiology to record neuronal activity in vivo.
• Quantified the degree and timescale of synchrony in cortical networks.

Main Results:

• Intrinsic neuronal properties were found to contribute minimally to spiking variability.
• Spiking variability predominantly arises from weakly synchronous network drive.
• The timescale of cortical synchrony dynamically shifts between 25 and 200 ms.
• Sensory input alters synchrony timescales, shifting from slow (spontaneous) to fast (driven) modes.
• This shift in synchrony timescale leads to reduced response variability across cortical areas.

Conclusions:

• Cortical spiking variability is primarily determined by network synchrony, not intrinsic neuronal properties.
• Dynamic modulation of synchrony timescales by sensory input regulates neuronal response reliability.
• Individual neurons respond reliably to physiological drive, with intrinsic properties influencing distinct neuronal responses and network synchrony stability.