Phase coding of spatial representations in the human entorhinal cortex

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• The entorhinal cortex is crucial for spatial navigation and memory.
• Grid-like cell activity in the entorhinal cortex forms an internal reference frame for self-localization.
• Neurons in this area exhibit phase coupling with local field oscillations.

Purpose of the Study:

• To investigate the role of spike timing relative to local field potentials in human entorhinal cortex during spatial navigation.
• To determine if phase locking encodes spatial information and forms environment-specific maps.
• To assess the predictive power of this neural code for position and heading.

Main Methods:

• Recording neural activity from the human entorhinal cortex during virtual navigation.
• Analyzing spike timing and phase locking with slow gamma band local field potentials (LFPs).
• Utilizing a Bayesian decoding model to predict avatar position and heading direction.

Main Results:

• Neurons showed consistent spatial and temporal phase locking between spikes and slow gamma LFPs.
• Phase locking created environment-specific spatial maps that were stable over time.
• Spatially periodic phase grids were observed, with environment-dependent scaling and alignment.
• A Bayesian decoding model achieved high accuracy in predicting the avatar's position and heading.

Conclusions:

• The phase of neuronal spikes relative to gamma oscillations encodes allocentric spatial positions in humans.
• A joint spatiotemporal phase code may underlie the neural representation of space and time in the entorhinal cortex.
• This finding offers insights into the neural mechanisms of human navigation and spatial cognition.