Low-Beta Oscillations Turn Up the Gain During Category Judgments

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Computational Neuroscience

Background:

• Neural synchrony, particularly in local field potential (LFP) rhythms, is hypothesized to enhance sensory processing.
• Cognitive functions like categorization may also leverage neural synchrony for improved performance, especially when distinctions are subtle.

Purpose of the Study:

• To investigate the role of neural synchrony in flexible categorization.
• To determine if category-specific patterns of synchrony exist in the lateral prefrontal cortex (PFC).
• To examine how synchrony changes with stimulus ambiguity and task relevance.

Main Methods:

• Monkeys were trained on a flexible categorization task using smoothly varying stimuli and orthogonal category boundaries.
• Low-beta (16-20 Hz) LFP synchrony in the lateral PFC was measured.
• Partial field-field coherence was used to assess local synchrony.

Main Results:

• Category-specific patterns of low-beta synchrony were observed in the lateral PFC, increasing when a particular category scheme was relevant.
• Low-beta LFP synchrony also increased for stimuli near the category boundary, indicating enhanced processing for difficult categorizations.
• Category selectivity was linked to local synchrony, while boundary enhancement appeared to be a more global effect.

Conclusions:

• Beta synchrony in the lateral PFC plays a role in forming category representations.
• Increased beta synchrony may reflect the recruitment of additional neural resources for categorizing challenging stimuli, acting as a form of cognitive gain control.
• Distinctions between local and global effects of synchrony were observed in categorization and boundary processing.