A new real-time multi-echo fMRI technique with gradient compensation of susceptibility related signal losses was used to measure activation in amygdala and hippocampus during 60 s trials of self-induced sadness. 9 healthy adults (3 males, 6 females, 22-45 years) performed a validated mood induction paradigm with sad and neutral faces in repeated scans (10 trials each, total trials: 235). This technique enabled online comparison with self-rating of sadness in single trials and immediate feedback of amygdala-hippocampus activation to the subject to reinforce mood induction. Activation of predominantly left amygdala-hippocampus during sad mood induction was observed in all subjects and in 77 % of single trials. This activation does not appear to diminish with repeated mood induction. The linear correlation between the intensity of amygdala-hippocampus activation and self-rating increased with repeated scanning, possibly reflecting adaptation to the mood induction procedure. These results suggest that amygdala...

INTRODUCTION Asymmetries of multiple components of the mammalian cerebrum have been described at various levels of organization. There has, however, never been a comprehensive examination of differences in brain structure in an inbred mouse strain. The ...

We combined event-related functional magnetic resonance imaging (fMRI) with olfactory classical conditioning to differentiate the neural responses evoked during appetitive and aversive olfactory learning. Three neutral faces [the conditioned stimuli (CS+)] were repetitively paired with pleasant, neutral, or unpleasant odors [the unconditioned stimuli (UCS)] in a partial reinforcement schedule. A fourth face was never paired to odor [the nonconditioned stimulus (CS−)]. Learning-related neural activity, comparing unpaired (face only) CS+ stimuli with CS−, showed valence-independent activations in rostral and caudal orbitofrontal cortex (OFC). Medial OFC responded to the appetitive (app) CS+, whereas lateral OFC responded to the aversive (av) CS+. Within nucleus accumbens, neural responses showed divergent activation profiles that increased with time in response to the appCS+ but decreased in response to the avCS+. In posterior amygdala, responses were elicited by the appCS+, which habituated over time. In te...

Diagnosing Autism Spectrum Disorder (ASD) with brain signals has received much attention in neuroscience and clinic diagnosis. It has been postulated that ASD is underpinned by atypical brain connectivity. Most analyses for neuroimaging data use correla...

We use a novel balanced experimental design to specifically investigate brain mechanisms underlying the modulating effect of expected pain intensity on afferent nociceptive processing and pain perception. We used two visual cues, each conditioned to one of two noxious thermal stimuli [∼48°C (high) or 47°C (low)]. The visual cues were presented just before and during application of the noxious thermal stimulus. Subjects reported significantly higher pain when the noxious stimulus was preceded by the high-intensity visual cue. To control for expectancy effects, for one-half of the runs, the noxious thermal stimuli were accompanied by the cue conditioned to the other stimulus. Comparing functional magnetic resonance imaging blood oxygenation level-dependent activations produced by the high and low thermal stimulus intensities presented with the high-intensity visual cue showed significant activations in nociceptive regions of the thalamus, second somatosensory cortex, and insular cortex. To isolate the effect...

Glioblastoma multiforme (GBM) is the most malignant, aggressive and common form of gliomas. Despite extensive research this situation has not changed significantly during the past decade. Currently, GBM is considered to be a homogenous mass histological...

The left-hand advantage seen during tactile discrimination tasks suggests hemispheric-processing asymmetry, although its neural substrates are not well known. We used functional magnetic resonance imaging to evaluate the laterality of the neural substrates involved in tactile discrimination in 19 normal volunteers. Passive tactile discrimination tasks, along with appropriate control tasks, were performed with both the right and left hands to evaluate the effects of the hand used and hemispheric effects (i.e., laterality of the activation pattern). Regardless of the hand used, the right dorsolateral prefrontal cortex, posterior parietal cortex, pre-supplementary motor area, and rostral portion of the dorsal premotor cortex (PMdr) were activated asymmetrically during tactile discrimination. This confirms the previous finding of a right-sided asymmetry for tactile shape discrimination. Hand effects were found in the left caudal portion of PMd (PMdc) adjacent to the central sulcus, which showed prominent activ...

Hormonal satiety signals secreted by the gut play a pivotal role in the physiological control of appetite. However, therapeutic exploitation of the gut–brain axis requires greater insight into the interaction of gut hormones with CNS circuits of appetite control. Using the manganese ion (Mn2+) as an activity-dependent magnetic resonance imaging (MRI) contrast agent, we showed an increase in signal intensity (SI) in key appetite-regulatory regions of the hypothalamus, including the arcuate, paraventricular, and ventromedial nuclei, after peripheral injection of the orexigenic peptide ghrelin. Conversely, administration of the anorexigenic hormone peptide YY3–36 caused a reduction in SI. In both cases, the changes in SI recorded in the hypothalamic arcuate nucleus preceded the effect of these peptides on food intake. Intravenous Mn2+ itself did not significantly alter ghrelin-mediated expression of the immediate early gene product c-Fos, nor did it cause abnormalities of behavior or metabolic parameters. We ...

Transcranial magnetic stimulation (TMS) is used therapeutically, and involves large (>10,000G) magnetic fields. Recent studies involving a clinical magnetic resonance imaging (MRI) system suggest that low (<10G) field magnetic stimulation (LFMS) can have mood-elevating actions in humans during depressive phases of bipolar disorder (Rohan et al 2003). We report here that a unidirectional, low-energy magnetic field that is a component of MRI has antidepressant-like effects in rats. Behavioral effects of the stimulation were examined in Sprague-Dawley rats using the forced swim test (FST), a two day procedure used in the study of depression, and fear conditioning (FC), a two day procedure used to study learning and memory. After 15 min exposure to forced swimming, rats received on each of 3 occasions 20 min of exposure to LFMS within the focal point of the field, LFMS outside the focal point of the field, or no LFMS (sham) within the focal point of the field. An MRI gradient head coil-based device provided LF...

Memories vary in their durability even when encoding conditions apparently remain constant. We investigated whether, under these circumstances, memory durability is nonetheless associated with variation in the neural activity elicited during encoding. Event-related functional magnetic resonance imaging data were acquired while volunteers semantically classified visually presented words. Using the “remember/know” procedure, memory for one-half of the words was tested after 30 min and for the remaining half after 48 h. In several regions, including left hippocampus and left dorsal inferior frontal gyrus (IFG), activity at encoding differed depending on whether items were later recollected regardless of study-test delay. Delay-selective effects were also evident, however. Recollection after 48 h was associated with enhanced activity in bilateral ventral IFG, whereas recollection after 30 min was associated with greater fusiform activity. Thus, there is a relationship between the neural activity elicited by an...