The timescale and magnitude of 1/f aperiodic activity decrease with cortical depth in humans, macaques, and mice

Abstract

Cortical dynamics obey a 1/f power law, exhibiting an exponential decay of spectral power with increasing frequency. The slope and offset of this 1/f decay reflect the timescale and magnitude of aperiodic neural activity, respectively. These properties are tightly linked to cellular and circuit mechanisms (e.g. excitation:inhibition balance, firing rates) as well as cognitive processes (perception, memory, state). However, the physiology underlying the 1/f power law in cortical dynamics is not well understood. Here, we compared laminar recordings from human, macaque and mouse cortex to evaluate how 1/f aperiodic dynamics vary across cortical layers and species. We report that 1/f slope is steepest in superficial layers and flattest in deep layers in each species. Additionally, the magnitude of this 1/f decay is greatest in superficial cortex and decreases with depth. Both of these findings can be accounted for by a simple model in which transmembrane currents have longer time constants and greater densities in superficial cortical layers. Together, our results provide novel mechanistic insight into aperiodic dynamics in cortex and suggest that the timescale and magnitude of aperiodic cortical currents decrease with cortical depth.

Human electromagnetic and haemodynamic networks systematically converge in unimodal cortex and diverge in transmodal cortex

“…Indeed, we find that the correspondence between haemodynamic and electromagnetic connectivity is associated with cytoarchitectural variation across the cortex, such that regions with higher density of granular cells have higher cross-modal correspondence, and vice versa. This is consistent with the notion that neural oscillations and the BOLD response mirror cytoarchitectural organization, as a result of distinct feedforward and feedback projections between different cortical layers and subcortical regions [20,35,51,97]. For example, previous studies of animal electrophysiological recordings demonstrated that visual and frontal cortex gamma activity can be localized to superficial cortical layers (supragranular layers I-III and granular layer IV), whereas alpha and beta activity are localized to deep, infragranular layers (layers V-IV) [8,9,20,72,73,100].…”

Periodic and aperiodic neural activity displays age-dependent changes across early-to-middle childhood

“…While this still represents a broad frequency range, and is consistent with other EEG studies utilising spectral parameterisation ( Carter Leno et al, 2021 , Cellier et al, 2021 , Merkin et al, 2021 , Robertson et al, 2019 ), future work could extend these analyses to even wider frequency ranges to capture higher frequency activity (e.g., > 40 Hz). This might be particularly useful for more directly comparing MEG and EEG derived data with results from local field potential and electrocorticography recordings (e.g., Gao et al, 2017 ; Halgren et al, 2021 ). Finally, emerging evidence indicating that the aperiodic exponent might act as a non-invasive measure of E/I balance ( Gao et al, 2017 , Waschke et al, 2021 ) opens exciting possibilities for research into the neurobiology of developmental and neuropsychiatric disorders linked to dysfunction within excitatory and inhibitory circuits, such as autism and schizophrenia ( Foss-Feig et al, 2017 ).…”

Periodic and Aperiodic Neural Activity Displays Age-Dependent Changes Across Early-to-Middle Childhood

“…While this still represents a broad frequency range, and is consistent with other EEG studies utilising spectral parameterisation (Carter Leno et al, 2021;Cellier et al, 2021;Merkin et al, 2021;Robertson et al, 2019), future work could extend these analyses to even wider frequency ranges to capture higher frequency activity (e.g., > 40 Hz). This might be particularly useful for more directly comparing MEG and EEG derived data with results from local field potential and electrocorticography recordings (e.g., Gao et al, 2017;Halgren et al, 2021). Finally, emerging evidence indicating that the aperiodic exponent might act as a non-invasive measure of E/I balance (Gao et al, 2017;Waschke et al, 2021) opens exciting possibilities for research into the neurobiology of developmental and neuropsychiatric disorders linked to dysfunction within excitatory and inhibitory circuits, such as autism and schizophrenia (Foss-Feig et al, 2017).…”