The Restless Brain

Abstract

The pressing need to better understand human brain organization is appreciated by all who have labored to explain the uniqueness of human behavior in health and disease. Early work on the cytoarchitectonics of the human brain by Brodmann and others accompanied by several centuries of lesion behavior work, although valuable, has left us far short of what we need. Fortunately, modern brain imaging techniques have, over the past 40 years, substantially changed the situation by permitting the safe appraisal of both anatomical and functional relationships within the living human brain. An unexpected feature of this work is the critical importance of ongoing, intrinsic activity, which accounts for the majority of brain's energy consumption and exhibits a surprising level of organization that emerges with dimensions of both space and time. In this essay, some of the unique features of intrinsic activity are reviewed, as it relates to our understanding of brain organization.

Structural and functional neuroplasticity in human learning of spatial routes

“…Despite such insights into its mechanisms, its evolutionarily beneficial effect on survival remains elusive. It reflects anatomical connectivity but is not constrained by it (Raichle, 2011).…”

“…We attempt for the first time to relate the learning-related changes in diffusivity in the spatial encoding network to fMRI-measured changes in both intrinsic FC and task-related FC across the network. The much slower, intrinsic synchronized fluctuations in BOLD signal intensity among regions are thought to reveal the networks of connectivity resulting from a history of co-activation (see Buckner et al (2013) and Raichle (2011), for recent reviews), whereas task-related FC is thought to reveal online changes in communication among regions necessitated by performance of the cognitive task. We ask whether very recent history (over the course of the previous hour) can effect changes in these networks that can be related to the learning that has occurred during that time.…”

Changes in resting-state brain networks after cognitive–behavioral therapy for chronic pain

“…the DMN including primarily the medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC), the SMN including somatosensory and motor cortices, the CEN including the DLPFC and posterior parietal cortex, and the DAN including the intraparietal sulcus/superior parietal lobule] (Fox & Raichle, 2007;Menon, 2011;Raichle, 2011), which were made using the spatial coordinates of the Anatomical Automatic Labeling (AAL) atlas via the MarsBar SPM Toolbox (http://www.sourceforge.net/projects/marsbar), and according to the largest correlation coefficients, identified the DMN, SMN, CEN, and DAN from 20 ICNs (online Supplementary Fig. S1 and Supplementary Table S1).…”

Relating Intrinsic Low-Frequency BOLD Cortical Oscillations to Cognition in Schizophrenia

“…Though hemodynamically generated, spontaneous low-frequency BOLD signal fluctuations show strong covariation with intracranial electrocorticographic and local field potential recordings, both for slow oscillations in the raw electrophysiological signals and for slow fluctuations in highfrequency (ie, gamma-band) power (He et al, 2008;Leopold et al, 2003). Correlations of spontaneous fluctuations of infraslow range (0.01-0.1 Hz) scalp potentials with resting BOLD signal fluctuations are spatially constrained within functional connectivity networks (Hiltunen et al, 2014), suggesting a role for infraslow fluctuations in functional brain organization (Raichle, 2011).…”

“…These BOLD signals are believed to reflect intrinsic neural oscillations important for modulating cortical excitability (Raichle, 2011). Though hemodynamically generated, spontaneous low-frequency BOLD signal fluctuations show strong covariation with intracranial electrocorticographic and local field potential recordings, both for slow oscillations in the raw electrophysiological signals and for slow fluctuations in highfrequency (ie, gamma-band) power (He et al, 2008;Leopold et al, 2003).…”