Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Thirty years of brain imaging research has converged to define the brain’s default network—a novel and only recently appreciated brain system that participates in internal modes of cognition Here we synthesize past observations to provide strong evidence that the default network is a specific, anatomically defined brain system preferentially active when individuals are not focused on the external environment Analysis of connectional anatomy in the monkey supports the presence of an interconnected brain system Providing insight into function, the default network is active when individuals are engaged in internally focused tasks including autobiographical memory retrieval, envisioning the future, and conceiving the perspectives of others Probing the functional anatomy of the network in detail reveals that it is best understood as multiple interacting subsystems The medial temporal lobe subsystem provides information from prior experiences in the form of memories and associations that are the building blocks of mental simulation The medial prefrontal subsystem facilitates the flexible use of this information during the construction of self-relevant mental simulations These two subsystems converge on important nodes of integration including the posterior cingulate cortex The implications of these functional and anatomical observations are discussed in relation to possible adaptive roles of the default network for using past experiences to plan for the future, navigate social interactions, and maximize the utility of moments when we are not otherwise engaged by the external world We conclude by discussing the relevance of the default network for understanding mental disorders including autism, schizophrenia, and Alzheimer’s disease

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The Brain's Default Network Anatomy, Function, and Relevance to Disease

Information about the basal ganglia has accumulated at a prodigious pace over the past decade, necessitating major revisions in our concepts of the structural and functional organization of these nuclei. From earlier data it had appeared that the basal ganglia served primarily to integrate diverse inputs from the entire cerebral cortex and to "funnel" these influences, via the ventrolateral thalamus, to the motor cortex (Allen & Tsukahara 1974, Evarts & Thach 1969, Kemp & Powell 1971). In particular, the basal

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Parallel Organization of Functionally Segregated Circuits Linking Basal Ganglia and Cortex

This paper describes FieldTrip, an open source software package that we developed for the analysis of MEG, EEG, and other electrophysiological data. The software is implemented as a MATLAB toolbox and includes a complete set of consistent and user-friendly high-level functions that allow experimental neuroscientists to analyze experimental data. It includes algorithms for simple and advanced analysis, such as time-frequency analysis using multitapers, source reconstruction using dipoles, distributed sources and beamformers, connectivity analysis, and nonparametric statistical permutation tests at the channel and source level. The implementation as toolbox allows the user to perform elaborate and structured analyses of large data sets using the MATLAB command line and batch scripting. Furthermore, users and developers can easily extend the functionality and implement new algorithms. The modular design facilitates the reuse in other software packages.

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FieldTrip: open source software for advanced analysis of MEG, EEG, and invasive electrophysiological data

I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Principles of Neural Science

Procedural Learning and Prefrontal Cortex

High frequency rTMS modulation of the sensorimotor networks: behavioral changes and fMRI correlates.

To investigate the effect of negative motor imagery on corticospinal excitability, we performed transcranial magnetic stimulation (TMS) studies in seven healthy subjects during imagination of suppressing movements. Subjects were asked to imagine suppression of TMS-induced twitching movement of their nondominant left hands by attempting to increase the amount of relaxation after receiving an auditory NoGo cue (negative motor imagery), but to imagine squeezing hands after a Go cue (positive motor imagery). Single- and paired-pulse TMS were triggered at 2 s after Go or NoGo cues. Motor-evoked potentials (MEPs) were recorded in the first dorsal interosseus (FDI), abductor pollicis brevis (APB), and abductor digiti minimi (ADM) muscles of the left hand. Paired-pulse TMS with subthreshold conditioning stimuli at interstimulus intervals of 2 (short intracortical inhibition) and 15 ms (intracortical facilitation) and that with suprathreshold conditioning stimuli at interstimulus interval of 80 ms (long intracortical inhibition) were performed in both negative motor imagery and control conditions. Compared with the control state (no imagination), MEP amplitudes of FDI (but not APB and ADM) were significantly suppressed in negative motor imagery, but those from all three muscles were unchanged during positive motor imagery. F-wave responses (amplitudes and persistence) were unchanged during both negative and positive motor imagery. During negative motor imagery, resting motor threshold was significantly increased, but short and long intracortical inhibition and intracortical facilitation were unchanged. The present results demonstrate that excitatory corticospinal drive is suppressed during imagination of suppressing movements.

Suppression of Corticospinal Excitability During Negative Motor Imagery

To evaluate the effect of movement amplitude on the "blood oxygen level-dependent effect," the authors studied six normal subjects while they extended their index finger with two different amplitudes. Images were analyzed using SPM96. In five subjects, the signal intensity increase in the primary sensorimotor area was significantly greater with the larger amplitude movement. In other areas of interest (supplementary motor area, premotor cortex, insula, postcentral area, cerebellum), the large-amplitude movement often showed significant activation when the small-amplitude movement did not. The authors conclude that, in studies of the motor system, movement amplitude needs to be controlled.

Mark Hallett

Papers

Procedural Learning and Prefrontal Cortex

High frequency rTMS modulation of the sensorimotor networks: behavioral changes and fMRI correlates.

Suppression of Corticospinal Excitability During Negative Motor Imagery

The effect of movement amplitude on activation in functional magnetic resonance imaging studies.

Treatment of focal dystonias with botulinum neurotoxin.