Critical scaling of novelty in the cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• The neocortex processes complex information for decision-making and behavior.
• Detecting novel or unexpected events is crucial for survival in uncertain environments.
• Mechanisms by which the neocortex detects novel stimuli are not well understood.

Purpose of the Study:

• To investigate how sparse, unanticipated neural activity influences local cortical circuitry.
• To determine if single neurons can mobilize large neural networks in response to novel stimuli.
• To explore the role of critical brain dynamics in detecting unexpected events.

Main Methods:

• Targeted holographic stimulation to evoke sparse "surprise" spikes in single pyramidal neurons.
• Two-photon imaging to monitor the effects of these spikes on neighboring neurons.
• Machine-learning classifiers to analyze information distribution related to stimulus origin.
• Cortical network simulations to validate experimental findings.

Main Results:

• Single "surprise" spikes triggered strong, transient recruitment of surrounding neurons, following a power-law distribution.
• Ongoing cortical activity exhibited neuronal avalanches, characteristic of systems near criticality.
• Information about the stimulus origin was reliably identifiable and distributed across the network.
• Simulations confirmed that observed scaling and information distribution align with predictions for critical systems.

Conclusions:

• The visual cortex exhibits amplified responses to small perturbations, a hallmark of criticality.
• Critical dynamics in the cortex enhance its capacity for detecting novel events.
• Sparse neural activity can effectively mobilize large-scale cortical networks.