Time as the fourth dimension in the hippocampus.

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• The perception and experience of time are fundamental to cognition.
• The hippocampal system is known for spatial processing and navigation.
• Its role in temporal processing, including memory and sequence learning, is increasingly recognized.

Purpose of the Study:

• To review key findings on hippocampal temporal processing in rodents and humans.
• To explore neural mechanisms underlying timing, sequence processing, and memory.
• To discuss computational models of hippocampal sequencing and temporal cognition.

Main Methods:

• Review of experimental findings in rats and human studies.
• Analysis of neural activity, including 'time cells' and ramping activity.
• Examination of 'online' sequence processing and 'off-line' replay during rest/sleep.
• Discussion of neural mechanisms (ion channels, oscillations, synaptic plasticity).
• Inclusion of computational neural network models.

Main Results:

• Hippocampal 'time cells' and lateral entorhinal cortex ramping cells track time.
• 'Online' and 'off-line' sequence processing by neuronal assemblies are identified.
• Human studies show parallels between episodic memory and sequence replay.
• Neural mechanisms involve cellular properties, network dynamics, and synaptic plasticity.
• Models suggest processes for scalar timing (Weber's Law) and event sequencing.

Conclusions:

• The hippocampal system plays a vital, multifaceted role in temporal processing and memory.
• Both 'online' and 'off-line' neural activity support sequence learning and memory.
• Neural mechanisms involve complex interactions at cellular and network levels.
• Computational models offer insights into the emergence of temporal cognition.