Changes of effective connectivity between the lateral and medial parts of the prefrontal cortex during a visual task

Structural equation modelling was used to study the change of connectivity during a visual task with continuous variation of the attention load. The model was based on areas defined by the haemodynamic responses described elsewhere [Mazoyer, P., Wicker, B. & Fonlupt, P. (2002) A neural network elicited by parametric manipulation of the attention load. Neuroreport, 13, 2331-2334], including occipitotemporal, parietal, temporal and prefrontal (lateral and medial areas) cortices. We have studied stationary- (which does not depend on the attentional load) and attention-related coupling between areas. This allowed the segregation of two subsystems. The first could reflect a system performing the integration step of the visual signal and the second a system participating in response selection. The major finding is the mutual negative influence between the lateral and medial parts of the prefrontal cortex. This negative influence between these two brain regions increased with the attention load. This is interpreted as a modification of the balance between integration and decision processes that are needed for the task to be efficiently completed.     

Executive control of spatial attention shifts in the auditory compared to the visual modality

Voluntary orienting of visual spatial attention has been shown to be associated with activation in a distributed network of frontal and parietal brain areas. Neuropsychological data suggest that at least some of these areas should be sensitive to the direction in which attention is shifted. The aim of this study was to use rapid event-related functional magnetic resonance imaging to investigate whether spatial attention in the auditory modality is subserved by the same or different brain areas as in the visual modality, and whether the auditory and visual attention networks show any degree of hemispheric lateralisation or sensitivity to the direction of attention shifts. The results suggest that auditory and visual spatial attention shifts are controlled by a supramodal network of frontal, parietal and temporal areas. Areas activated included the precuneus and superior parietal cortex, the inferior parietal cortex and temporo-parietal junction, as well as the premotor and supplementary motor areas and dorsolateral prefrontal cortex (DLPFC). In the auditory task, some of these areas, in particular the precuneus as well as the inferior parietal cortex and temporo-parietal junction, showed 'relative' asymmetry, in that they responded more strongly to attention shifts towards the contralateral than the ipsilateral hemispace. Some areas, such as the right superior parietal cortex and left DLPFC, showed 'absolute' asymmetry, in that they responded more strongly in one than in the other hemisphere.     

Dissociating the effects of Sternberg working memory demands in prefrontal cortex

Earlier neuroimaging studies of working memory (WM) have demonstrated that dorsolateral prefrontal cortex (DLPFC) activity increases as maintenance and load demand increases. However, few studies have carefully disambiguated these two WM processes at the behavioral and physiological levels. The objective of the present functional resonance imaging (fMRI) study was to map within prefrontal cortex locales that are selectively load sensitive, delay sensitive, or both. We studied 18 right-handed normal subjects with fMRI at 3 Tesla during a block design version of the Sternberg task. WM load was manipulated by varying the memory set size (3, 5, or 8 letters). The effect of memory maintenance was examined by employing two time delays (1 s and 6 s) between the letter set and probe stimuli. The DLPFC was strongly activated in load manipulation, whereas activation as a function of delay was restricted to the left premotor regions and Broca's areas. Moreover, regions of prefrontal cortex on the right (BA 46) were found to be exclusively affected by load. These results suggest the possibility that top-down modulation of attention or cognitive control at encoding and/or decisionmaking may be mediated by these areas.     

Supramodal effects of covert spatial orienting triggered by visual or tactile events

Event-related functional magnetic resonance imaging was used to identify brain areas involved in spatial attention and determine whether these operate unimodally or supramodally for vision and touch. On a trial-by-trial basis, a symbolic auditory cue indicated the most likely side for the subsequent target, thus directing covert attention to one side. A subsequent target appeared in vision or touch on the cued or uncued side. Invalidly cued trials (as compared with valid trials) activated the temporo-parietal junction and regions of inferior frontal cortex, regardless of target modality. These brain areas have been associated with multimodal spatial coding in physiological studies of the monkey brain and were linked to a change in the location that must be attended to in the present study. The intraparietal sulcus and superior frontal cortex were also activated in our task, again, regardless of target modality, but did not show any specificity for invalidly cued trials. These results identify a supramodal network for spatial attention and reveal differential activity for inferior circuits involving the temporo-parietal junction and inferior frontal cortex (specific to invalid trials) versus more superior intraparietal-frontal circuits (common to valid and invalid trials).     

Regional distribution of tau, beta-amyloid and beta-amyloid precursor protein in the Alzheimer's brain: a quantitative immunolabelling study

Regional variation in the distribution of SP and NFT within the brain is well documented. Consideration of such variation is potentially of help in formulating models of disease progression. Several models propose that pathological changes in Alzheimer's disease (AD) progress in a step-wise fashion along neuronally connected regions. In this study, we measured tau, Abeta and betaAPP load in different brain regions and examined our results against models of AD progression. Blocks of brain tissue from 45 AD and 15 control cases were immunolabelled for tau, Abeta and betaAPP. Immunolabelled areas were measured as a proportion of the area of the field. Tau load was almost twice as great in the entorhinal cortex than elsewhere in the brain and was least in the cingulate gyrus. In contrast, Abeta was greatest in the cingulate gyrus and least in the entorhinal cortex. BetaAPP rankings were similar to those of tau. Thus the site with the greatest Abeta load (cingulate cortex) had the least tau and the site with the greatest tau load (entorhinal cortex) had the least Abeta. The entorhinal and cingulate cortex are neuronally interconnected. Our results might be explained on the basis that a neurone with its cell body in the entorhinal cortex and axonal terminals in the cingulate cortex shows predominately tau pathology in relation to the cell body and predominately Abeta pathology in relation to its axonal terminals. We conclude that our observations are consistent with previously described models of AD progression. It is possible that tau-rich neurones are associated through their projections to Abeta rich sites. Further work of this kind analysing differential pathological profiles in interconnected brain regions may contribute to refining this model.     

Modulation and task effects in auditory processing measured using fMRI

Active listening has been reported to elicit a different sensory response from passive listening and is generally observed as an increase in the magnitude of activation. Sensory activation differences may therefore be masked by the effect of attention. The present study measured activation induced by static and modulated tones, while controlling attention by using target-discrimination and passive listening tasks. The factorial design enabled us to determine whether the stimulus-induced activation in auditory cortex was independent of the information-processing demands of the task. Contrasted against a silent baseline, listening to the tones induced widespread activation in the temporal cortex, including Heschl's gyrus (HG), planum temporale, superior temporal gyrus (STG), and superior temporal sulcus. No additional auditory areas were recruited in the response to modulated tones compared to static tones, but there was an increase in the response in the STG, anterior to HG. Relative to passive listening, the active task increased the response in the STG, posterior to HG. The active task also recruited regions in the frontal and parietal cortex and subcortical areas. These findings indicate that preferential responses to the changing spectro-temporal properties of the stimuli and to the target-discrimination task involve distinct, non-overlapping areas of the secondary auditory cortex. Thus, in the present study, differences in sensory activation were not masked by the effects of attention.     

Spatial attention can modulate audiovisual integration at multiple cortical and subcortical sites

The role of attention in multisensory integration (MI) is presently uncertain, with some studies supporting an automatic, pre-attentive process and others suggesting possible modulation through selective attention. The goal of this functional magnetic resonance imaging study was to investigate the role of spatial attention on the processing of congruent audiovisual speech stimuli (here indexing MI). Subjects were presented with two simultaneous visual streams (speaking lips in the left and right visual hemifields) plus a single central audio stream (spoken words). In the selective attention conditions, the auditory stream was congruent with one of the two visual streams. Subjects attended to either the congruent or the incongruent visual stream, allowing the comparison of brain activity for attended vs. unattended MI while the amount of multisensory information in the environment and the overall attentional requirements were held constant. Meridian mapping and a lateralized 'speaking-lips' localizer were used to identify early visual areas and to localize regions responding to contralateral visual stimulations. Results showed that attention to the congruent audiovisual stimulus resulted in increased activation in the superior temporal sulcus, striate and extrastriate retinotopic visual cortex, and superior colliculus. These findings demonstrate that audiovisual integration and spatial attention jointly interact to influence activity in an extensive network of brain areas, including associative regions, early sensory-specific visual cortex and subcortical structures that together contribute to the perception of a fused audiovisual percept.     

Association fiber pathways to the frontal cortex from the superior temporal region in the rhesus monkey

The projections to the frontal cortex that originate from the various areas of the superior temporal region of the rhesus monkey were investigated with the autoradiographic technique. The results demonstrated that the rostral part of the superior temporal gyrus (areas Pro, Ts1, and Ts2) projects to the proisocortical areas of the orbital and medial frontal cortex, as well as to the nearby orbital areas 13, 12, and 11, and to medial areas 9, 10, and 14. These fibers travel to the frontal lobe as part of the uncinate fascicle. The middle part of the superior temporal gyrus (areas Ts3 and paAlt) projects predominantly to the lateral frontal cortex (areas 12, upper 46, and 9) and to the dorsal aspect of the medial frontal lobe (areas 9 and 10). Only a small number of these fibers terminated within the orbitofrontal cortex. The temporofrontal fibers originating from the middle part of the superior temporal gyrus occupy the lower portion of the extreme capsule and lie just dorsal to the fibers of the uncinate fascicle. The posterior part of the superior temporal gyrus projects to the lateral frontal cortex (area 46, dorsal area 8, and the rostralmost part of dorsal area 6). Some of the fibers from the posterior superior temporal gyrus run initially through the extreme capsule and then cross the claustrum as they ascend to enter the external capsule before continuing their course to the frontal lobe. A larger group of fibers curves round the caudalmost Sylvian fissure and travels to the frontal cortex occupying a position just above and medial to the upper branch of the circular sulcus. This latter pathway constitutes a part of the classically described arcuate fasciculus.     

A relation between rest and the self in the brain?

Neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) are widely used to identify the cerebral correlates of cognitive tasks. The resting state presents the advantage to serve as a reference in all experiments but is also an ill-defined mental state because it may vary both from one subject to another and within the same subject. The most challenging question concerns the areas whose activity (revealed by PET or fMRI imaging) is greater in rest state than in an active condition. The present work reports the result of a meta-analysis including five previously published studies. The five different tasks involved are the following: attribution of intention, judgement of stimulus pleasantness, discrimination of spatial attributes, judgement of other peoples' belief and perception of gaze.For each study, the general linear model was used to assess statistical difference and a contrast resting state minus other conditions was calculated. The intersection of the five contrasts was used to search for the variation jointly observed across the different experiments. This lead to a reduced number of clusters: one cluster in the lower/anterior part of the cingulate gyrus and four clusters located in the medial/superior frontal gyrus, along the superior frontal sulcus.We discuss the location of these areas with respect to the location of activations induced by different tasks: externally focused attention, memory, general reasoning, theory of mind and self-referential tasks. We observed that medial prefrontal cortex exhibits a lower activity when the subject's attention is focused towards the external world than when the subject has to additionally refer to some internal states. By contrast, this activity is greater during resting state than during both externally directed and internally directed attention. Thus, we hypothesize that during rest, the subject is in a state where he refers only to his own self.     

Functional imaging during covert auditory attention in multiple sclerosis

Recent literature suggests that the brain in multiple sclerosis (MS) undergoes reorganization that subserves the performance of visual and motor tasks. We identified sites of cerebral activity in 16 MS patients while performing a covert attention (CA) task, presented in the auditory modality. Positron emission tomography (PET) revealed activation of rostral/dorsal anterior cingulate cortex (ACC) in normal subjects studied previously. Activity in this region was not significant in MS patients, but there was a large region of activity in superior temporal cortex. Decreased activation of frontal attentional networks and greater activity in sensory/perceptual cortical areas (auditory association cortex) suggests a reduction of transmission along white matter tracts connecting these regions. This study demonstrates cingulate hypoactivity and cerebral reorganization during auditory attention in MS.     

Organization of visual inputs to the inferior temporal and posterior parietal cortex in macaques.

It has been proposed that visual information in the extrastriate cortex is conveyed along 2 major processing pathways, a "dorsal" pathway directed to the posterior parietal cortex, underlying spatial vision, and a "ventral" pathway directed to the inferior temporal cortex, underlying object vision. To determine the relative distributions of cells projecting to the 2 pathways, we injected the posterior parietal and inferior temporal cortex with different fluorescent tracers in 5 rhesus monkeys. The parietal injections included the ventral intraparietal (VIP) and lateral intraparietal (LIP) areas, and the temporal injections included the lateral portions of cytoarchitectonic areas TE and TEO. There was a remarkable segregation of cells projecting to the 2 systems. Inputs to the parietal cortex tended to arise either from areas that have been implicated in spatial or motion analysis or from peripheral field representations in the prestriate cortex. By contrast, inputs to the temporal cortex tended to arise from areas that have been implicated in form and color analysis or from central field representations. Cells projecting to the parietal cortex were found in visual area 2 (V2), but only in the far peripheral representations of both the upper and lower visual field. Likewise, labeled cells found in visual areas 3 (V3) and 4 (V4) were densest in their peripheral representations. Heavy accumulations of labeled cells were found in the dorsal parieto-occipital cortex, including the parieto-occipital (PO) area, part A of V3 (V3A), and the dorsal prelunate area (DP). In the superior temporal sulcus, cells were found within several motion-sensitive areas, including the middle temporal area (MT), the medial superior temporal area (MST), the fundus of the superior temporal area (FST), and the superior temporal polysensory area (STP), as well as within anterior portions of the sulcus whose organization is as yet poorly defined. Cells projecting to areas TE and TEO in the temporal cortex were located within cytoarchitectonic area TG at the temporal pole and cytoarchitectonic areas TF and TH on the parahippocampal gyrus, as well as in noninjected portions of area TE buried within the superior temporal sulcus. In the prestriate cortex, labeled cells were found in V2, V3, and V4, but, in contrast to the loci labeled after parietal injections, those labeled after temporal injections were concentrated in the foveal or central field representations. Although few double-labeled cells were seen, 2 regions containing intermingled parietal- and temporal-projection cells were area V4 and the cortex at the bottom of the anterior superior temporal sulcus.(ABSTRACT TRUNCATED AT 400 WORDS)     

Increased brain activity in frontal and parietal cortex underlies the development of visuospatial working memory capacity during childhood.

The aim of this study was to identify changes in brain activity associated with the increase in working memory (WM) capacity that occurs during childhood and early adulthood. Functional MRI (fMRI) was used to measure brain activity in subjects between 9 and 18 years of age while they performed a visuospatial WM task and a baseline task. During performance of the WM task, the older children showed higher activation of cortex in the superior frontal and intraparietal cortex than the younger children did. A second analysis found that WM capacity was significantly correlated with brain activity in the same regions. These frontal and parietal areas are known to be involved in the control of attention and spatial WM. The development of the functionality in these areas may play an important role in cognitive development during childhood.     

On the neural basis of focused and divided attention

Concepts of higher attention functions distinguish focused and divided attention. The present study investigated whether these mental abilities are mediated by common or distinct neural substrates. In a first experiment, 19 healthy subjects were examined with functional brain imaging (fMRI) while they attended to either one or both of two simultaneously presented visual information streams and responded to repetitive stimuli. This experiment resembled a typical examination of these mental functions with the single task demanding focused and the dual task conditions requiring divided attention. Both conditions activated a widespread, mainly right-sided network including dorso- and ventrolateral prefrontal structures, superior and inferior parietal cortex, and anterior cingulate gyrus. Under higher cognitive demands of divided attention, activity in these structures was enhanced and left-sided homologues were recruited. In a second experiment investigating another 17 subjects with almost the same paradigm, it was accounted for that in most dual task investigations of focused and divided attention the single tasks are easier to process than their combined presentation. Therefore, the task difficulty of focused attention tasks was increased. Almost the same activity pattern observed during division of attention was now found during focusing attention. Comparing both attentional states matched for task difficulty, differences were found in visual but not in prefrontal or parietal cortex areas. Our results suggest that focused and divided attention depend on largely overlapping neuronal substrates. Differences in activation patterns, especially in prefrontal and parietal areas, may result from unequal demands on executive control due to disparate processing requirements in typical tasks of focused and divided attention: Easier conditions begin with mainly right-sided activity within the attention network. As conditions become more difficult, left-lateralized homologue areas activate.     

Hemispheric lateralization of cerebral blood-flow changes during selective listening to dichotically presented continuous speech

Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) while subjects were selectively listening to continuous speech delivered to one ear and ignoring concurrent speech delivered to the opposite ear, as well as concurrent text or letter strings running on a screen. rCBF patterns associated with selective listening either to the left-ear or right-ear speech message were compared with each other and with rCBF patterns in two visual-attention conditions in which the subjects ignored both speech messages and either read the text or discriminated the meaningless letter strings moving on the screen. Attention to either speech message was associated with enhanced activity in the superior temporal cortex of the language-dominant left hemisphere, as well as in the superior and middle temporal cortex of the right hemisphere suggesting enhanced processing of prosodic features in the attended speech. Moreover, enhanced activity during attention to either speech message was observed in the right parietal areas known to have an important role in directing spatial attention. Evidence was also found for attentional tuning of the left and right auditory cortices to select information from the contralateral auditory hemispace.     

Cortical projections to the superior colliculus in tree shrews (Tupaia belangeri)

The visuomotor functions of the superior colliculus depend not only on direct inputs from the retina, but also on inputs from neocortex. As mammals vary in the areal organization of neocortex, and in the organization of the number of visual and visuomotor areas, patterns of corticotectal projections vary. Primates in particular have a large number of visual areas projecting to the superior colliculus. As tree shrews are close relatives of primates, and they are also highly visual, we studied the distribution of cortical neurons projecting to the superior colliculus by injecting anatomical tracers into the colliculus. Since projections from visuotopically organized visual areas are expected to match the visuotopy of the superior colliculus, injections at different retinotopic locations in the superior colliculus provide information about the locations and organization of topographic areas in extrastriate cortex. Small injections in the superior colliculus labeled neurons in locations within areas 17 (V1) and 18 (V2) that are consistent with the known topography of these areas and the superior colliculus. In addition, the separate locations of clusters of labeled cells in temporal visual cortex provide evidence for five or more topographically organized areas. Injections that included deeper layers of the superior colliculus also labeled neurons in medial frontal cortex, likely in premotor cortex. Only occasional labeled neurons were observed in somatosensory or auditory cortex. Regardless of tracer injection location, we found that, unlike primates, a substantial projection to the superior colliculus from posterior parietal cortex is not a characteristic of tree shrews. J. Comp. Neurol. 521:1614–1632, 2013. © 2012 Wiley Periodicals, Inc.     

Fronto-parietal networks activation during the contingent negative variation period

The preparation for stimuli and responses in which the position and required finger to respond are cued, produces the preparatory activation of the specific neural resources that are going to be needed for the completion of the task. The focus of the present report is to evaluate if the fronto-parietal networks activated in fMRI studies during endogenous attention are also activated during the CNV period using EEG recording. The behavioural responses and 64 EEG channels were recorded during an S1-S2 paradigm similar to Posner central cue paradigms. The LORETA analysis based in the averaging of the z-LORETA values showed that the Brodmann's areas with the highest activation during the CNV period were in the medial and superior frontal areas, fronto-parietal lateral areas (including the premotor cortex) and extrastriate visual cortex. These results suggest that in addition to the previously described activation in premotor-motor, posterior sensory and superior and medial frontal areas, the activation of fronto-parietal networks is a main contributor to the CNV, indicating the endogenous attentional effort during the CNV period.     

Heritability of brain volume, surface area and shape: an MRI study in an extended pedigree of baboons

To evaluate baboons (Papio hamadryas) as a primate model for the study of the genetic control of brain size and internal structure, we performed high resolution (<500 microm) magnetic resonance imaging on 109 pedigreed baboons. Quantitative genetic analysis of these MR images using a variance components approach indicates that native (untransformed) brain volume exhibits significant heritability among these baboons (h(2) = 0.52, P = 0.0049), with age and sex also accounting for substantial variation. Using global spatial normalization, we transformed all images to a standard population-specific reference, and recalculated the heritability of brain volume. The transformed images generated heritability estimates of h(2) = 0.82 (P = 0.00022) for total brain volume, h(2) = 0.86 (P = 0.0006) for cerebral volume, h(2) = 0.73 (P = 0.0069) for exposed surface area of the cerebrum and h(2) = 0.67 (P = 0.01) for gray matter volume. Regional differences in the genetic effects on brain structure were calculated using a voxel-based morphometry (VBM) approach. This analysis of regional variation shows that some areas of motor cortex and the superior temporal gyrus show relatively high heritability while other regions (e.g. superior parietal cortex) exhibit lower heritability. The general pattern of regional differences is similar to that observed in previous studies of humans. The present study demonstrates that there is substantial genetic variation underlying individual variation in brain size and structure among Papio baboons, and that broad patterns of genetic influence on variation in brain structure may be similar in baboons and humans.     

Specialization in the default mode: Task‐induced brain deactivations dissociate between visual working memory and attention

The idea of an organized mode of brain function that is present as default state and suspended during goal‐directed behaviors has recently gained much interest in the study of human brain function. The default mode hypothesis is based on the repeated observation that certain brain areas show task‐induced deactivations across a wide range of cognitive tasks. In this event‐related functional resonance imaging study we tested the default mode hypothesis by comparing common and selective patterns of BOLD deactivation in response to the demands on visual attention and working memory (WM) that were independently modulated within one task. The results revealed task‐induced deactivations within regions of the default mode network (DMN) with a segregation of areas that were additively deactivated by an increase in the demands on both attention and WM, and areas that were selectively deactivated by either high attentional demand or WM load. Attention‐selective deactivations appeared in the left ventrolateral and medial prefrontal cortex and the left lateral temporal cortex. Conversely, WM‐selective deactivations were found predominantly in the right hemisphere including the medial‐parietal, the lateral temporo‐parietal, and the medial prefrontal cortex. Moreover, during WM encoding deactivated regions showed task‐specific functional connectivity. These findings demonstrate that task‐induced deactivations within parts of the DMN depend on the specific characteristics of the attention and WM components of the task. The DMN can thus be subdivided into a set of brain regions that deactivate indiscriminately in response to cognitive demand (“the core DMN”) and a part whose deactivation depends on the specific task. Hum Brain Mapp, 2010. © 2009 Wiley‐Liss, Inc.     

Selective auditory attention effects in tonotopically organized cortical areas: A topographic ERP study

This study reinvestigates some aspects of the neurophysiological mechanisms of auditory selective attention, by testing the hypothesis that auditory attention can exert a selective control over the sensory processing of acoustic stimuli in tonotopic auditory cortex. Event-related potentials (ERPs) were recorded from human subjects while they listened selectively to a tone sequence in one ear and ignored a concurrent sequence of a different frequency in the opposite ear. The tone frequencies were 500, 1,000, 2,000, or 4,000 Hz in separate sequences, and were delivered at a constant rate of one every 800 ms. The effects of attention were analyzed in the difference waves obtained by subtracting ERPs to ignore tones from those of the same tones when attended. The earliest effect of attention (70–80 ms post-stimulus) was found to present the same spatio-temporal organization as the obligatory, sensory-evoked N1 wave, with similar tonotopic changes in scalp distribution with the tone frequencies. At longer latencies, two other attentional effects were observed, of probable endogenous origin: one around 175 ms post-stimulus, possibly originating from non-tonotropic auditory cortex, and the latest one (after 300 ms) from non-specific areas. The results support the hypothesis of a genuine sensory gating mechanism for auditory attention, taking place in tonotopic auditory cortex at an early stage of sensory processing, even in low attentional load conditions. © 1995 Wiley-Liss, Inc.     

Maintaining structured information: an investigation into functions of parietal and lateral prefrontal cortices

Working memory--including simple maintenance of information as well as manipulation of maintained information--has been long associated with lateral prefrontal cortex (PFC). More recently, evidence has pointed to an important role for posterior parietal cortex (PPC) in supporting working-memory processes as well. While explanations have emerged as to the nature of parietal involvement in working-memory maintenance, the apparent involvement of this region in working-memory manipulation has not been fully accounted for. We have hypothesized that parietal cortex, through its representation of spatial information, in conjunction with dorsolateral PFC, supports organization of information (manipulation) and the maintenance of information in an organized state. Through computational modeling, we have demonstrated how this might be achieved. Presently, we consider a pair of fMRI experiments that were designed to test our hypothesis. Both experiments involved simple working-memory delay tasks with contrasts between maintenance of information in organized and unorganized states, as well as contrasts between high and low working-memory load conditions. Two different kinds of organization, associative (grouping) and relational, were employed in the two studies. Across both studies, superior parietal cortex (BA 7) demonstrated a significant increase in activity associated with maintenance of information in an organized state, over and above any increases associated with increased working-memory load. During the delay period, dorsolateral PFC (BA 9) exhibited similar increases for both organization and load; however, this region was particularly engaged by organization demand during the initial cue period. Functional connectivity analysis indicates interaction between dorsolateral prefrontal cortex (DLPFC) and superior parietal cortex, especially when organization is required.