Building hierarchically nested structure by rapid neural sequences

Area of Science:

• Cognitive Neuroscience
• Neurobiology of Cognition
• Computational Neuroscience

Background:

• Hierarchically nested structures are crucial for complex human cognition, underpinning language, planning, and mathematics.
• The precise neural mechanisms supporting the flexible construction of these hierarchical structures remain largely unknown.

Purpose of the Study:

• To investigate the neural computations underlying the brain's ability to construct hierarchically nested structures.
• To identify the specific neural operations and their associated brain activity patterns involved in hierarchical sequence building.

Main Methods:

• Participants mentally constructed sequences with nested, multi-depth structures using recursive rule application.
• Magnetoencephalography (MEG) was employed to record neural activity during the task.
• Analysis focused on identifying neural signatures associated with hierarchical processing and sequence generation.

Main Results:

• The brain constructs nested hierarchies via rapid neural sequences performing two generative operations.
• Operation 1: Identifying hierarchy depth (linked to ripple-band power).
• Operation 2: Ordering symbols within a level (scales with depth, correlates with planning time).

Conclusions:

• Neural computations for hierarchical structure building involve distinct generative operations.
• These findings illuminate a fundamental neural process for converting sensory input into structured representations essential for higher cognition.