Neural Correlates of Spatial Navigation in Primate Hippocampus / 神经科学通报·英文版

The hippocampus has been extensively implicated in spatial navigation in rodents and more recently in bats. Numerous studies have revealed that various kinds of spatial information are encoded across hippocampal regions. In contrast, investigations of spatial behavioral correlates in the primate hippocampus are scarce and have been mostly limited to head-restrained subjects during virtual navigation. However, recent advances made in freely-moving primates suggest marked differences in spatial representations from rodents, albeit some similarities. Here, we review empirical studies examining the neural correlates of spatial navigation in the primate (including human) hippocampus at the levels of local field potentials and single units. The lower frequency theta oscillations are often intermittent. Single neuron responses are highly mixed and task-dependent. We also discuss neuronal selectivity in the eye and head coordinates. Finally, we propose that future studies should focus on investigating both intrinsic and extrinsic population activity and examining spatial coding properties in large-scale hippocampal-neocortical networks across tasks.

Spectral Analysis of Polysomnography in Narcolepsy

OBJECTIVE: This study was conducted to identify differences between people with narcolepsy and the normal control of delta and theta activity using electroencephalogram (EEG) spectrum analysis of nocturnal polysomnography (PSG). METHODS: Seven narcolepsy patients and seven age-sex matched normal controls underwent PSG and multiple sleep latency tests. Participants' non-rapid eye movement (NREM) sleep EEGs in PSG was analyzed using a Fast Fourier Transform technique. RESULTS: While NREM delta activity of people with narcolepsy declined during the first three periods of NREM, there was no change during the 4th period of NREM. The increase in NREM theta activity also lasted until the 3rd period of NREM but did not occur during the 4th period of NREM. In comparing sleep parameters, REM sleep latency in the narcolepsy group was significantly shorter than in controls. CONCLUSION: These results suggest that people with narcolepsy are likely to have a delta and theta activity-related sleep disturbance mechanism in NREM sleep.