title: Human intracranial high-frequency activity during memory processing: neural oscillations or stochastic volatility?
abstract: Intracranial high-frequency activity (HFA), which refers to fast fluctuations in electrophysiological recordings, increases during memory processing. Two views have emerged to explain this effect: (1) HFA reflects a synchronous signal, related to underlying gamma oscillations, that plays a mechanistic role in human memory and (2) HFA reflects an asynchronous signal that is a non-specific marker of brain activation. We review recent data supporting each of these views and conclude that HFA during memory processing is more consistent with an asynchronous signal. Memory-related HFA is therefore best conceptualized as a biomarker of neural activation that can functionally map memory with high spatial and temporal precision.
authors.affiliation: University of Pennsylvania, Department of Psychology, Philadelphia, PA 19104, United States.
authors.forename: John F
authors.initials: JF
authors.lastname: Burke
authors.affiliation: University of Pennsylvania, Department of Psychology, Philadelphia, PA 19104, United States.
authors.forename: Ashwin G
authors.initials: AG
authors.lastname: Ramayya
authors.affiliation: University of Pennsylvania, Department of Psychology, Philadelphia, PA 19104, United States. Electronic address: kahana@psych.upenn.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kahana
mesh_terms: D001683:Biological Clocks; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D065818:Gamma Rhythm / Q000502:physiology*; D006801:Humans; D008568:Memory / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D013269:Stochastic Processes