title: Human intracranial high-frequency activity maps episodic memory formation in space and time.
abstract: Noninvasive neuroimaging studies have revealed a network of brain regions that activate during human memory encoding; however, the relative timing of such activations remains unknown. Here we used intracranially recorded high-frequency activity (HFA) to first identify regions that activate during successful encoding. Then, we leveraged the high-temporal precision of HFA to investigate the timing of such activations. We found that memory encoding invokes two spatiotemporally distinct activations: early increases in HFA that involve the ventral visual pathway as well as the medial temporal lobe and late increases in HFA that involve the left inferior frontal gyrus, left posterior parietal cortex, and left ventrolateral temporal cortex. We speculate that these activations reflect higher-order visual processing and top-down modulation of attention/semantic information, respectively.
authors.affiliation: Neuroscience Graduate Group, University of Pennsylvania, 19104, USA. Electronic address: jfburke@med.upenn.edu.
authors.forename: John F
authors.initials: JF
authors.lastname: Burke
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Long
authors.forename: Kareem A
authors.initials: KA
authors.lastname: Zaghloul
authors.forename: Ashwini D
authors.initials: AD
authors.lastname: Sharan
authors.forename: Michael R
authors.initials: MR
authors.lastname: Sperling
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kahana
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D058256:Brain Waves / Q000502:physiology*; D002648:Child; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D061212:Memory, Episodic; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: Electrocorticography; Functional mapping; Gamma; HFA; High-frequency activity; IFG; Inferior frontal gyrus; LFA; Low-frequency activity; Memory; PPC; Posterior parietal cortex; SM; Subsequent memory; VLTC; Ventrolateral temporal cortex