Spontaneous Spiking Is Governed by Broadband Fluctuations

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Cortical neurons exhibit rhythmic spontaneous activity, observable in local field potentials (LFP).
• Researchers often interpret LFP as containing narrowband oscillations with functional significance.
• An alternative view posits neural activity is fundamentally broadband and nonstationary.

Purpose of the Study:

• To determine if spiking activity aligns better with narrowband LFP oscillations or broadband LFP fluctuations.
• To test competing models of neocortical population activity: narrowband oscillators versus broadband dynamics.

Main Methods:

• Recorded local field potentials (LFP) and spiking activity from marmoset neocortex.
• Compared the predictive power of narrowband LFP phase versus broadband LFP phase on spike timing.
• Utilized narrowband filtering and broadband measures of LFP fluctuations.

Main Results:

• The phase of broadband LFP fluctuations was a superior predictor of spike timing compared to narrowband LFP phases.
• This indicates that spontaneous spiking activity is more closely associated with broadband dynamics.

Conclusions:

• Neocortical activity dynamics are better characterized as intrinsically broadband rather than composed of discrete narrowband oscillators.
• The findings challenge narrowband interpretations and support broadband models for describing moment-to-moment cortical activity.