A temporal record of the past with a spectrum of time constants in the monkey entorhinal cortex
| Autor: | Marc W. Howard, Elizabeth A. Buffalo, Nathanael A Cruzado, Ian M. Bright, Miriam L. R. Meister, Zoran Tiganj |
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| Rok vydání: | 2020 |
| Předmět: |
Male
Time Factors Laplace transform Event (relativity) Memory Episodic Hippocampus Macaque memory 03 medical and health sciences 0302 clinical medicine biology.animal Animals Primate Episodic memory time 030304 developmental biology Neurons 0303 health sciences Multidisciplinary entorhinal cortex Behavior Animal Relaxation (psychology) biology Time constant Biological Sciences Entorhinal cortex Macaca mulatta Afterimage nervous system Neuroscience 030217 neurology & neurosurgery |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | 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. Episodic memory is believed to be intimately related to our experience of the passage of time. Indeed, neurons in the hippocampus and other brain regions critical to episodic memory code for the passage of time at a range of timescales. The origin of this temporal signal, however, remains unclear. Here, we examined temporal responses in the entorhinal cortex of macaque monkeys as they viewed complex images. Many neurons in the entorhinal cortex were responsive to image onset, showing large deviations from baseline firing shortly after image onset but relaxing back to baseline at different rates. This range of relaxation rates allowed for the time since image onset to be decoded on the scale of seconds. Further, these neurons carried information about image content, suggesting that neurons in the entorhinal cortex carry information about not only when an event took place but also, the identity of that event. Taken together, these findings suggest that the primate entorhinal cortex uses a spectrum of time constants to construct a temporal record of the past in support of episodic memory. |
| Databáze: | OpenAIRE |
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