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 hippocampus is critical for consolidation of new information. Unless exposed to neurodegenerative conditions, its adult volume changes little with aging, possibly owing to regional neurogenesis. Continued structural modification could render the hippocampus vulnerable to cumulative environmental events, especially when measured in late adulthood. We investigated the contributions of genes and environment to MRI-derived hippocampal and temporal horn volumes in 44 monozygotic (MZ) and 40 dizygotic (DZ) elderly male twin pairs, 68-78 years. Neither hippocampal volume correlated with age (left r=.02, right r=.07), whereas temporal horn volume/age correlations were significant even in this restricted age range (left r=.20, right r=.23, p<.01). Intraclass correlations (ICC) for each twin zygosity were significant and greater in MZ than DZ pairs. For total hippocampal volume ICCs were .50 in MZ and .38 in DZ, whereas for temporal horn ICCs were .77 in MZ and .43 in DZ. Maximum likelihood model fitting reveale...

The insular cortex receives direct connections from primary olfactory structures such as the piriform cortex, anterior olfactory nucleus and primary olfactory bulb. Based upon these connections an olfactory related function within the insular cortex would be expected, yet such a relationship has not been clearly characterized. Using whole brain fMRI, we have identified a discrete region of the human posterior insular cortex which responds to different olfactory stimuli over successive exposures both within and between experimental sessions. Further, this activity appears highly dependent upon the number of odorant exposures and the length of time between odorant exposures, possibly reflecting habituation at a hemodynamic and presumably neural level. We propose that this olfactory-responsive region of the posterior insular cortex performs a previously unrealized role in olfaction and the insular cortex may be a key player in olfactory related sensation. This work was supported by the Cornell/Rockefeller/Slo...

Prefrontal anomalies in psychiatric disorders are often preceded early in life by disruptions in parental care. Genetic risk factors may play an equally influential role as revealed by the human twin-study approach. To test for genetic and social effects on prefrontal cortical volumes in squirrel monkeys, this study combined a paternal half-sibling analysis with three postnatal conditions that altered aspects of early maternal care. In one condition, offspring were periodically removed from natal groups between 13-21 weeks of age. Differences in maternal availability were produced in two other conditions by manipulating the effort required to find food. Whole brain T1-weighted 3D-FSPGR images were obtained 3-5 years later from all 39 young adults. Significantly larger right than left prefrontal volumes were discerned, although left and right cerebral hemispheric measures did not differ. Both genetic and postnatal rearing related differences were evident in the right but not left prefrontal cortex. Asymmetr...

We tested the hypothesis that activation of voltage-gated Na+ channels and glutamate (GLU) release underlies functional magnetic resonance imaging (fMRI) signal based on the blood oxygenation level dependent (BOLD) during somatosensory activation. The BOLD fMRI experiments were performed at 7 Tesla on α-chloralose anesthetized rats undergoing forepaw stimulation before and for successive times after the application of lamotrigine (LTG), which is a neuronal voltage-gated Na+ channel blocker and GLU release inhibitor. LTG led to a time-dependent attenuation of the BOLD fMRI signal increase in somatosensory cortex during forepaw stimulation of 72% between 60-90 min after administration. BOLD signal during forepaw stimulation declined significantly from 7.2±1.0% before LTG to 2.0±2.3% (P<0.0016), while the volume of the activated region declined from 5.9±0.9 mm3 to 0.9±1.0 mm3 (P<0.0001). These results strongly suggest that voltage-gated Na+ channels and GLU release are involved in the BOLD fMRI response durin...

The primary somatosensory cortex (SI) is widely appreciated for its somatotopic organization of responses to innocuous mechanical stimuli; however, little is known regarding the possible organization of SI responses to noxious stimulation. This within-subject fMRI study compares the spatial distribution of SI responses to innocuous and noxious stimuli presented to the fingers during psychophysical discrimination tasks. Functional MRI data were recorded during 2 separate sessions–one involving innocuous and noxious thermal stimuli (44.0°& 53.0°C) applied to digits 1 and 5, and another in which innocuous vibrotactile stimuli (75, 100, and 125Hz) were applied to the same digits. Initial experiments demonstrate significant activation in SI for both noxious thermal and innocuous vibrotactile stimuli (p< 0.0001). Comparison of data within experimental runs demonstrates significant spatial separation of SI responses evoked by stimulation of digits 1 and 5 for both innocuous vibrotactile (X²; p< 0.0001) and noxiou...

The very high sensitivity and specificity of odor identification tasks in discriminating between Alzheimer’s patients (AD) and normals suggests its utility in reflecting the presence of underlying neuropathology. Significant neuropathological changes are seen in areas critical to processing olfactory information, even in the early stages of AD. This study investigated whether performance on olfactory tasks was related to volumetric measures of mesial temporal areas central to olfactory processing and important in the neuropathology of early AD (hippocampus, parahippocampal area, amygdala), obtained with structural MRI, in 13 AD patients and 23 age-matched controls, diagnosed at the UCSD ADRC. Robust relationships were observed between left hippocampal volume and the functional measures that were greater for 1) AD patients than for controls, 2) for the San Diego Odor Identification Test (ODOR ID, r = .85) and the Boston Naming Test (BNT, r = .74) than for odor or taste threshold. The robust relationship bet...

We investigated whether spatial vs. non-spatial working memory (WM) performance is associated with a lateralized pattern of cortical activation when stimuli are identical and only task demands differ. We presented 10 healthy right-handed subjects (6 male, 4 female, mean age 33 ± 8) with a set of target shapes that appeared in particular locations. Subjects were required to remember either the location (spatial task) or shape (non-spatial task) of the targets and to respond by indicating whether or not each probe was in the memorized set. We used a 3.0T Siemens Allegra scanner and a gradient echo sequence (TR/TE/Flip = 2000ms/30ms/90°). We compared signal changes in the spatial vs. non-spatial WM epochs in both individual subjects and in the group-averaged data. Although the spatial task was performed more quickly (F(1,9)=535, p<.0001) and as accurately (F(1,9)=2.98, p=.12) as the non-spatial task, it was associated with increased activation in regions associated with WM including dorsolateral prefrontal co...

Objective: Pansori is a Korean traditional vocal music that has a unique story and melody which converts deep emotion of pain and sorrow into art. The objective of this study is to illustrate the different cortical activation by a Korean traditional opera, Pansori, accoding to its emotional valence using functional MRI (fMRI). Subjects and Methods: Ten right-handed volunteers participated. Their mean age was 25.2. Activation tasks were designed to passively listen a part of Pansori with sad or humorous emotional valence. White noise was introduced for control task. Imaging was conducted on a 1.5T Siemens Vision scanner. Single-shot EPI fMRI scans (TR/TE 3840/40 ms, flip angle 90, FOV 220, 64 x 64 matrix, 6 mm) were acquired in 20 contiguous slices. Imaging data were motion-corrected, coregistered, normalized, and smoothened using SPM-96 software. Results: Bilateral posterior temporal regions were activated in both of Pansori tasks with different hemispheric asymmetry. After subtraction between two tasks, a...