title: Age-Related Changes in 1/f Neural Electrophysiological Noise.
abstract: Aging is associated with performance decrements across multiple cognitive domains. The neural noise hypothesis, a dominant view of the basis of this decline, posits that aging is accompanied by an increase in spontaneous, noisy baseline neural activity. Here we analyze data from two different groups of human subjects: intracranial electrocorticography from 15 participants over a 38 year age range (15-53 years) and scalp EEG data from healthy younger (20-30 years) and older (60-70 years) adults to test the neural noise hypothesis from a 1/f noise perspective. Many natural phenomena, including electrophysiology, are characterized by 1/f noise. The defining characteristic of 1/f is that the power of the signal frequency content decreases rapidly as a function of the frequency (f) itself. The slope of this decay, the noise exponent (χ), is often <-1 for electrophysiological data and has been shown to approach white noise (defined as χ = 0) with increasing task difficulty. We observed, in both electrophysiological datasets, that aging is associated with a flatter (more noisy) 1/f power spectral density, even at rest, and that visual cortical 1/f noise statistically mediates age-related impairments in visual working memory. These results provide electrophysiological support for the neural noise hypothesis of aging. Significance statement: Understanding the neurobiological origins of age-related cognitive decline is of critical scientific, medical, and public health importance, especially considering the rapid aging of the world's population. We find, in two separate human studies, that 1/f electrophysiological noise increases with aging. In addition, we observe that this age-related 1/f noise statistically mediates age-related working memory decline. These results significantly add to this understanding and contextualize a long-standing problem in cognition by encapsulating age-related cognitive decline within a neurocomputational model of 1/f noise-induced deficits in neural communication.
authors.affiliation: Departments of Neurology and bradley.voytek@gmail.com.
authors.forename: Bradley
authors.identifier: http://orcid.org/0000-0003-1640-2525
authors.initials: B
authors.lastname: Voytek
authors.affiliation: Department of Mathematics and Statistics, Boston University, Boston, Massachusetts 02215, and.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Kramer
authors.affiliation: Helen Wills Neuroscience Institute and.
authors.forename: John
authors.initials: J
authors.lastname: Case
authors.affiliation: Department of Mathematics and Statistics, Boston University, Boston, Massachusetts 02215, and.
authors.forename: Kyle Q
authors.initials: KQ
authors.lastname: Lepage
authors.affiliation: Departments of Neurology and.
authors.forename: Zechari R
authors.initials: ZR
authors.lastname: Tempesta
authors.affiliation: Helen Wills Neuroscience Institute and Department of Psychology, University of California, Berkeley, California 94720.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Knight
authors.affiliation: Departments of Neurology and Physiology and Psychiatry and UCSF Center for Integrative Neuroscience, University of California, San Francisco, California 94158.
authors.forename: Adam
authors.initials: A
authors.lastname: Gazzaley
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D055724:Electrophysiological Phenomena / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009622:Noise; D013057:Spectrum Analysis; D055815:Young Adult
keywords: 1/f; EEG; electrocorticography; neural noise; phase/amplitude coupling; working memory