An MRI time course of 512 echo-planar images (EPI) in resting human brain obtained every 250 ms reveals fluctuations in signal intensity in each pixel that have a physiologic origin. Regions of the sensorimotor cortex that were activated secondary to hand movement were identified using functional MRI methodology (FMRI). Time courses of low frequency (< 0.1 Hz) fluctuations in resting brain were observed to have a high degree of temporal correlation (P < 10(-3)) within these regions and also with time courses in several other regions that can be associated with motor function. It is concluded that correlation of low frequency fluctuations, which may arise from fluctuations in blood oxygenation or flow, is a manifestation of functional connectivity of the brain.

Functional connectivity in the motor cortex of resting human brain using echo-planar MRI.

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

/pdf/parallel-organization-of-functionally-segregated-circuits-159qr6wgp1.pdf

Parallel Organization of Functionally Segregated Circuits Linking Basal Ganglia and Cortex

Assessments of anterior cingulate cortex in experimental animals and humans have led to unifying theories of its structural organization and contributions to mammalian behaviour. The anterior cingulate cortex forms a large region around the rostrum of the corpus callosum that is termed the anterior executive region. This region has numerous projections into motor systems, however, since these projections originate from different parts of anterior cingulate cortex and because functional studies have shown that it does not have a uniform contribution to brain functions, the anterior executive region is further subdivided into ‘affect’ and ‘cognition’ components. The affect division includes areas 25, 33 and rostral area 24, and has extensive connections with the amygdala and periaqueductal grey, and parts of it project to autonomic brainstem motor nuclei. In addition to regulating autonomic and endocrine functions, it is involved in conditioned emotional learning, vocalizations associated with expressing internal states, assessments of motivational content and assigning emotional valence to internal and external stimuli, and maternal—infant interactions. The cognition division includes caudal areas 24' and 32', the cingulate motor areas in the cingulate sulcus and nociceptive cortex. The cingulate motor areas project to the spinal cord and red nucleus and have premotor functions, while the nociceptive area is engaged in both response selection and cognitively demanding information processing. The cingulate epilepsy syndrome provides important support of experimental animal and human functional imaging studies for the role of anterior cingulate cortex in movement, affect and social behaviours. Excessive cingulate activity in cases with seizures confirmed in anterior cingulate cortex with subdural electrode recordings, can impair consciousness, alter affective state and expression, and influence skeletomotor and autonomic activity. Interictally, patients with anterior cingulate cortex epilepsy often display psychopathic or sociopathic behaviours. In other clinical examples of elevated anterior cingulate cortex activity it may contribute to tics, obsessive—compulsive behaviours, and aberrent social behaviour. Conversely, reduced cingulate activity following infarcts or surgery can contribute to behavioural disorders including akinetic mutism, diminished self-awareness and depression, motor neglect and impaired motor initiation, reduced responses to pain, and aberrent social behaviour. The role of anterior cingulate cortex in pain responsiveness is suggested by cingulumotomy results and functional imaging studies during noxious somatic stimulation. The affect division of anterior cingulate cortex modulates autonomic activity and internal emotional responses, while the cognition division is engaged in response selection associated with skeletomotor activity and responses to noxious stimuli. Overall, anterior cingulate cortex appears to play a crucial role in initiation, motivation, and goal-directed behaviours. The anterior cingulate cortex is part of a larger matrix of structures that are engaged in similar functions. These structures form the rostral limbic system and include the amygdala, periaqueductal grey, ventral striatum, orbitofrontal and anterior insular cortices. The system formed by these interconnected areas assesses the motivational content of internal and external stimuli and regulates context-dependent behaviours.

Contributions of anterior cingulate cortex to behaviour.

The Prefrontal Cortex, Fifth Edition, provides users with a thoroughly updated version of this comprehensive work that has historically served as the classic reference on this part of the brain. The book offers a unifying, interdisciplinary perspective that is lacking in other volumes written about the frontal lobes, and is, once again, written by the award-winning author who discovered "memory cells," the physiological substrate of working memory. The fifth edition constitutes a comprehensive update, including all the major advances made on the physiology and cognitive neuroscience of the region since publication in 2008. All chapters have been fully revised, and the overview of prefrontal functions now interprets experimental data within the theoretical framework of the new paradigm of cortical structure and dynamics (the Cognit Paradigm), addressing the accompanying social, economic, and cultural implications. * Provides a distinctly interdisciplinary view of the prefrontal cortex, covering all major methodologies, from comparative anatomy to modern imaging* Unique analysis and synthesis of a large body of basic and clinical data on the subject (more than 2000 references)* Written by an award-winning author who discovered "memory cells," the physiological substrate of working memory* Synthesizes evidence that the prefrontal cortex constitutes a complex pre-adaptive system* Incorporates emerging study of the role of the frontal lobes in social, economic, and cultural adaptation

The prefrontal cortex

The use of positron emission tomography to measure regional changes in average blood flow during processing of individual auditory and visual words provides support for multiple, parallel routes between localized sensory-specific, phonological, articulatory and semantic-coding areas.

https://bi.snu.ac.kr/Courses/4ai05s/Essay/1-25.pdf

Positron emission tomographic studies of the cortical anatomy of single-word processing

1. Previous studies in man have revealed a coupling between the regional cerebral blood flow (rCBF) and the regional cerebral metabolic rate for oxygen. In normal man, increases in the regional cerebral metabolic rate for oxygen leads to proportional increases in the rCBF(34). We have measured the rCBF as an expression of the level of cortical activity simultaneously from 254 cortical regions in 28 patients with no major neurological defects, during rest and during planning and execution of a few types of learned voluntary movements with the hand. 2. We found that the rCBF increases exclusively in the supplementary motor area while subjects were programming a sequence of fast isolated movements of individual fingers, without actually executing it. 3. During execution of the same motor sequence, there were equivalent increases of the rCBF in both supplementary motor areas, but only in the contralateral primary motor area. In addition, there were more modest rCBF increases in the contralateral sensory hand area, the convexity part of the premotor area, and bilaterally in the inferior frontal region. 4. Repetitive fast flexions of the same finger or a sustained isometric muscular contraction raise the blood flow in the contralateral primary motor and sensory hand area. 5. A pure somatosensory discrimination of the shapes of objects, without any concomitant voluntary movements, also leaves the supplementary motor areas silent. 6. We conclude that the primary motor area and the part of the motor system it projects to by itself can control ongoing simple ballistic movements with the self-same body part. A sequence of different isolated finger movements requires programming in the supplementary motor areas. We suggest that the supplementary motor areas are programming areas for motor subroutines and that these areas form a queue of time-ordered motor commands before voluntary movement are executed by way of the primary motor area.

Supplementary motor area and other cortical areas in organization of voluntary movements in man

Regional cerebral blood flow (rCBF) was measured in 254 areas of a hemisphere with the xenon 133 intraarterial injection method. Six cases of classic migraine were followed from the normal state into the prodromal phase, and in 3 cases further into the headache phase. One patient with common migraine was similarly followed during his only classic attack. The attacks were initiated by focal hyperemia in 3 patients. During prodromes all patients displayed occipitoparietal rCBF reduction (oligemia), but in only 1 case did the reduction approach critical values. Oligemia gradually spread anteriorly in the course of 15 to 45 minutes. In 4 patients a global oligemia was observed. In 4 patients severe headache was present concomitantly with oligemia and with no sign of hyperemia or nonhomogeneous brain perfusion. The normal rCBF increase during cortical activity (hand movement, speech, and similar activities) was impaired in 6 patients. The results indicate that the vasospastic model of the migraine attack is too simplistic.

Focal hyperemia followed by spreading oligemia and impaired activation of rcbf in classic migraine

1. This paper reports regional cerebral blood flow (rCBF) measurements in 254 cortical regions with 133Xe injected into the internal carotid artery in 19 patients, none of whom had any major neurological defect. The purpose was to demonstrate the pattern of cortical activity, as revealed by rCBF increases, during two types of unilateral voluntary movement in extrapersonal space: a) the maze test, series of fast isolated movements in various directions in a frame, executed under verbal command; and b) the drawing of a spiral in the air. 2. Both types of movements were associated with increases of rCBF in the supplementary motor area (bilaterally), the convexity part of the premotor area (bilaterally), the primary sensorimotor hand and arm area (contralaterally), and in the superior and inferior parietal region (bilaterally). 3. During the maze test there were, in addition, bilateral focal increases of the blood flow in the auditory areas, the inferior frontal regions, and the frontal eye fields. 4. It is concluded that the supplementary motor areas, which are also active during programming and execution of movement sequences in intrapersonal space (33), elaborate programs for motor subroutines necessary in skilled voluntary motion. The convexity parts of the premotor areas are activated when a new motor program is established or a previously learned motor program is modulated. The primary motor area is the exclusive executive locus for voluntary movements of the hand and arm. 5. Voluntary movements in extrapersonal space only are associated with activation of the parietal regions. These areas are assumed to provide information to the motor programming neurons about the demanded direction of motion in extrapersonal space in relation to proprioceptive reference systems. 6. The increase of rCBF in the auditory areas, the inferior frontal regions, and the frontal eye fields during the maze test were ascribed to the processing of auditory information. 7. Both tests are accompanied by a diffuse increase of the hemispheric blood flow (approximately 10%), which is assumed to be a parallel to the commonly known desynchronization of the EEG during mental work.

B. Larsen

Papers

Supplementary motor area and other cortical areas in organization of voluntary movements in man

Focal hyperemia followed by spreading oligemia and impaired activation of rcbf in classic migraine

Different cortical areas in man in organization of voluntary movements in extrapersonal space

Variations in regional cortical blood flow in the right and left hemispheres during automatic speech.

The common migraine attack may not be initiated by cerebral ischaemia