Considerable insight into the architecture of reasoning could be gained by isolating the network of brain areas that supports this essential function. This study employed fMRI and a deductive reasoning task, performed either with visual or auditory stimuli, to identify the modality-independent brain areas associated with reasoning. Anatomical and functional images were acquired on a GE Signa 1.5T scanner equipped for echoplanar imaging. The activation epoch consisted of 10 trials where each trial included the presentation of two arguments and the production of a conclusion. A voxel-by-voxel, multistage statistical analysis and a logical AND operation isolated those voxels that were associated with the task performed in both sensory modalities. A conservation stage identified the supra-modal brain regions that were conserved across all 7 subjects. The pattern of brain regions that subserved reasoning consisted of left inferior frontal gyrus (Brodmann's areas (BA) 44 and 45), medial frontal gyrus (BA 6), and...

Does the sustained, elevated neural activity observed during working memory tasks reflect the short-term retention of information? Functional magnetic resonance imaging (fMRI) data of delayed recognition of visual motion in human participants were analyzed with two methods: a general linear model (GLM) and multivoxel pattern analysis. Although the GLM identified sustained, elevated delay-period activity in superior and lateral frontal cortex and in intraparietal sulcus, pattern classifiers were unable to recover trial-specific stimulus information from these delay-active regions. The converse—no sustained, elevated delay-period activity but successful classification of trial-specific stimulus information—was true of posterior visual regions, including area MT+ (which contains both middle temporal area and medial superior temporal area) and calcarine and pericalcarine cortex. In contrast to stimulus information, pattern classifiers were able to extract trial-specific task instruction-related information fro...

The aim of our study is to develop non invasive approaches to follow the fate, viability and migratory potential of progenitor cells following transplantation using super high resolution positron emission tomography (PET) and magnetic resonance imaging (MRI). We labeled rat subventricular zone (SVZ) progenitor cells and control cell line (PC12, pheochromocytoma cells) using 18F-fluorodeoxyglucose for PET studies and dendrimer-encapsulated super paramagnetic particles (Feredex) for MRI. These labeled cells were transplanted into the striatum or rostral migratory stream (RMS) of normal and 6-OHDA lesioned rats. During a period of 2 months, transplanted progenitor cells were easily identifiable with MRI. SVZ cells implanted into the RMS migrated after one week retention time toward olfactory bulb as seen with MRI. Slow migration of the cells implanted into the striatum was observed after 3 weeks. Histological analyses using Nissl, Iron stain, H&E and Fluoro-Jade, allowed delineation of the transplantation sit...

Trial-by-trial variability in perceptual performance on identical stimuli has been related to spontaneous fluctuations in ongoing activity of intrinsic functional connectivity networks (ICNs). In a paradigm requiring sustained vigilance for instance, we previously observed that higher prestimulus activity in a cingulo-insular-thalamic network facilitated subsequent perception. Here, we test our proposed interpretation that this network underpins maintenance of tonic alertness. We used simultaneous acquisition of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) in the absence of any paradigm to test an ensuing hypothesis, namely that spontaneous fluctuations in this ICN′s activity (as measured by fMRI) should show a positive correlation with the electrical signatures of tonic alertness (as recorded by concurrent EEG). We found in human subjects (19 male, 7 female) that activity in a network comprising dorsal anterior cingulate cortex, anterior insula, anterior prefrontal cortex ...

Brain-imaging studies have shown that voluntary swallowing activates a distributed network of cortical regions including the lateral sensorimotor cortex, anterior cingulate cortex (ACC), insula and operculum. Previous research has implicated these regions in both planning and execution of voluntary motion. Therefore, the present study sought to differentiate the functional contributions of these foci in the (1) planning, and (2) execution of voluntary saliva swallowing. The experiment consisted of a delayed response task in which a visual cue instructing the subject to prepare to swallow was presented 10-12 seconds prior to a second visual cue instructing the subject to swallow. Seven healthy subjects (mean age = 27.7 ± 3.4 years) performed the task while laryngeal movement data were simultaneously recorded to verify swallowing events. Contrast analyses indicated that activations within the lateral sensorimotor cortex and ACC were significantly greater (pcorrected < 0.01) during swallowing planning than du...

CCHS patients show impaired ventilatory responses to CO2 and hypoxia, a reduced drive to breathe during sleep, and aberrant cardiovascular responses to blood pressure elevation, suggesting deficient central neural regulatory processes. We examined fMRI signal changes in the brain for thirteen CCHS patients (age: mean 11, and range 8-15 years; no Hirschsprung’s, pulmonary, cardiac or neuromuscular disease) and fourteen age- and gender-matched control subjects to forced expiratory effort, a challenge that induces blood pressure elevation. Two fMRI series were collected while patients lay supine in the scanner. The first series was a 150 s baseline, where subjects breathed normally through a mouthpiece; the second consisted of 30 s baseline, followed by 120 s forced expiratory effort, where subjects breathed against a closed glottis. Images were adjusted for slice timing differences, motion corrected, spatially normalized, segmented into gray matter, smoothed and intensity normalized. Random-effects analysis ...

Cortical reorganization occurring in multiple sclerosis (MS) patients is thought to play a key role in limiting the effect of structural tissue damage. Conversely, its exhaustion may contribute to the irreversible disability that accumulates with disease progression. Several aspects of MS-related cortical reorganization, including the overall functional effect and likely modulation by therapies, still remain to be elucidated. The aim of this work was to assess the extent of functional cortical reorganization and its brain structural/pathological correlates in Dark Agouti rats with experimental autoimmune encephalomyelitis (EAE), a widely accepted preclinical model of chronic MS. Morphological and functional MRI (fMRI) were performed before disease induction and during the relapsing and chronic phases of EAE. During somatosensory stimulation of the right forepaw, fMRI demonstrated that cortical reorganization occurs in both relapsing and chronic phases of EAE with increased activated volume and decreased la...

To examine brain substrates of stress physiology and cognitive functions affected by age, we measured plasma levels of cortisol and adrenocorticotropic hormone (ACTH), sensitivity to glucocorticoid negative feedback regulation, performance on learning and memory tests, and the volume of prefrontal brain regions in healthy 5-17 year old female squirrel monkeys. Sexual maturity occurs at 3 years, and the average maximum lifespan is 21 years. No age-related differences were discerned on initial spatial learning and memory tests, nor at baseline for levels of cortisol and ACTH. But older monkeys responded with larger stress-induced increases in ACTH due in part to diminished glucocorticoid sensitivity determined by administration of hydrocortisone. Older monkeys also made significantly more errors on tests of reversal learning and memory that required inhibition and cognitive flexibility. Contrary to evidence from human neuroimaging, neither prefrontal gray nor white matter volumes were diminished in older squ...

Prior studies in neurophysiology have discovered that neurons that share similar tuning functions also tend to exhibit trial-by-trial correlated activity. This form of noise correlation (NC) is denoted as tuning-compatible noise correlation (TCNC) becau...

In the early 1970s, the nascent Society set up an office with NAS support and concentrated on fostering a new interdisciplinary approach to brain and behavior research. This was an exciting period for the field, with such developments as the isolation of the opioid receptors in the brain, which heightened public interest in “natural highs” and solutions to the problems of pain and addiction; the fields of learning and memory enhanced by Tim Bliss and Terje Lomo’s description of long-term potentiation and Eric Kandel’s findings that habituation and sensitization altered the strength of synaptic connections, which enhanced the fields of learning and memory; and the introduction of CT, MRI, and PET scanners which made the interior of the brain visible during behavior.