Frequency-specific network connectivity increases underlie accurate spatiotemporal memory retrieval

• Published in: Nature neuroscience Vol. 16; no. 3; pp. 349 - 356
• Main Authors: Watrous, Andrew J, Tandon, Nitin, Conner, Chris R, Pieters, Thomas, Ekstrom, Arne D
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.03.2013; Nature Publishing Group
• Subjects: 631/378/1595; 631/378/1697; 631/378/2649; Adult; Animal Genetics and Genomics; Behavioral Sciences; Biological Techniques; Biomedicine; Brain; Brain - physiology; Brain - physiopathology; Brain Mapping; Cortex (parietal); Epilepsy - physiopathology; Functional Neuroimaging; Humans; Hypotheses; Memory; Memory - physiology; Mental Recall - physiology; Nerve Net - physiology; Nerve Net - physiopathology; Neural networks; Neurobiology; Neuropsychological Tests; Neurosciences; Physiological aspects; Space Perception - physiology; United States; United States > US; Texas; California
• ISSN: 1097-6256; 1546-1726; 1546-1726
• DOI: 10.1038/nn.3315

Using simultaneous electrocorticographical recordings in multiple lobes in human subjects performing memory retrieval tasks, this study finds that oscillatory coupling across a network of brain regions predicts successful memory recall. The study also shows that this increased network connectivity converges at the medial temporal lobe, with different neural signatures for spatial versus temporal components of episodic memory retrieval. The medial temporal lobes, prefrontal cortex and parts of parietal cortex form the neural underpinnings of episodic memory, which includes remembering both where and when an event occurred. However, the manner in which these three regions interact during retrieval of spatial and temporal context remains untested. We employed simultaneous electrocorticographical recordings across multilobular regions in patients undergoing seizure monitoring while they retrieved spatial and temporal context associated with an episode, and we used phase synchronization as a measure of network connectivity. Successful memory retrieval was characterized by greater global connectivity compared with incorrect retrieval, with the medial temporal lobe acting as a hub for these interactions. Spatial versus temporal context retrieval resulted in prominent differences in both the spectral and temporal patterns of network interactions. These results emphasize dynamic network interactions as being central to episodic memory retrieval, providing insight into how multiple contexts underlying a single event can be recreated in the same network.