Electrical engineering

Neuroscience

Mathematics

Biology

Statistics

Engineering

Cognitive psychology

Psychology

Entorhinal cortex

Hippocampus

Neuron

Stimulus (psychology)

Computer science

Timeline

Time constant

Proceedings of the National Academy of Sciences

Significance Many brain regions, notably the hippocampus, contain a record of the recent past with time cells, neurons that fire in sequence, each at a specific time after a triggering event. The origin of this neural timeline has been unclear. This paper reports a timing signal in the entorhinal cortex (EC), which provides input to the hippocampus. Rather than firing sequentially, all EC neurons activated shortly after a stimulus and then decayed at a variety of rates. Because different neurons decay at different rates, one can reconstruct how far in the past the stimulus was presented by noting which neurons are still active. These results align well with the theoretical proposal that the brain represents the real Laplace transform of the past.

A temporal record of the past with a spectrum of time constants in the monkey entorhinal cortex