Frontotemporal dementia (FTD) shows autosomal dominant transmission in up to a third of families, enabling the study of presymptomatic and prodromal phases. Despite self-reported well-being and normal daily cognitive functioning, structural magnetic res...

The precise location of the human female genital representation field in the primary somatosensory cortex (S1) is controversial and its capacity for use-associated structural variation as a function of sexual behavior remains unknown. We used a functional magnetic resonance imaging (fMRI)-compatible sensory-tactile stimulation paradigm to functionally map the location of the female genital representation field in 20 adult women. Neural response to tactile stimulation of the clitoral region (vs right hand) identified individually-diverse focal bilateral activations in dorsolateral areas of S1 (BA1–BA3) in alignment with anatomic location. We next used cortical surface analyses to assess structural thickness across the 10 individually most activated vertices per hemisphere for each woman. We show that frequency of sexual intercourse within 12 months is correlated with structural thickness of the individually-mapped left genital field. Our results provide a precise functional localization of the female genita...

While the pathological changes induced by the loss of dopamine innervation in the basal ganglia by Parkinson's disease are well studied, little is known about functional changes in the neural circuitry of this area during normal aging. Accordingly we have analyzed age-associated changes in the basal ganglia of behaviorally characterized, awake rhesus monkeys, using pharmacological MRI to map responses to dopaminergic stimulation. Apomorphine, a mixed D1/D2 dopamine receptor agonist, significantly reduced neural activity in the substantia nigra (SN) of young adult rhesus monkeys, while evoking little change in aged animals. Compared to young animals, both apomorphine and amphetamine (an indirect D1/D2 dopamine receptor agonist) significantly increased activation of the aged rhesus globus pallidus externa (GPe). In addition, the aged animals showed decreased activity in the putamen in response to amphetamine administration. The changes in SN, GPe and putamen activation are consistent with the concept that ba...

The white matter (WM) architecture of the human brain changes in response to training, though fine-grained temporal characteristics of training-induced white matter plasticity remain unexplored. We investigated white matter microstructural changes using diffusion tensor imaging at five different time points in 26 sighted female adults during 8 months of training on tactile braille reading. Our results show that training-induced white matter plasticity occurs both within and beyond the trained sensory modality, as reflected by fractional anisotropy (FA) increases in somatosensory and visual cortex, respectively. The observed changes followed distinct time courses, with gradual linear FA increase along the training in the somatosensory cortex and sudden visual cortex cross-modal plasticity occurring after braille input became linguistically meaningful. WM changes observed in these areas returned to baseline after the cessation of learning in line with the supply–demand model of plasticity. These results also...

Postmortem studies indicate a temporal sequence of primary allocortical and secondary neocortical degeneration during Alzheimer disease (AD) progression. Hippocampus (HC) atrophy correlates with allocortical neuronal degeneration and atrophy of the corpus callosum (CC) reflects loss of intracortical projecting pyramidal neurons in neocortex. First, we wanted to determine the temporal sequence and rate of degeneration of HC and CC in AD. Second, to answer the question, whether rates of atrophy were correlated with rates of cognitive decline and third, whether both markers could be proposed as potential morphological parameters for mapping drug effects on brain structure in longitudinally studied AD patients and healthy control subjects. MRI-derived measures of CC and HC were compared between 27 clinically diagnosed AD patients and 28 age- and gender-matched healthy control subjects. Rates of CC and HC atrophy were determined in 21 AD patients and 10 control subjects studied longitudinally. We found mean rel...

Background: Fragile X syndrome (FXS) is a genetic condition affecting neurodevelopment. Humans with FXS down to 6 months old demonstrate abnormal white matter microstructure[1]. A previous ex vivo diffusion weighted MRI (dMRI) study found delayed cerebe...

In models of visual spatial attention control, it is commonly held that top–down control signals originate in the dorsal attention network, propagating to the visual cortex to modulate baseline neural activity and bias sensory processing. However, the precise distribution of these top–down influences across different levels of the visual hierarchy is debated. In addition, it is unclear whether these baseline neural activity changes translate into improved performance. We analyzed attention-related baseline activity during the anticipatory period of a voluntary spatial attention task, using two independent functional magnetic resonance imaging datasets and two analytic approaches. First, as in prior studies, univariate analysis showed that covert attention significantly enhanced baseline neural activity in higher-order visual areas contralateral to the attended visual hemifield, while effects in lower-order visual areas (e.g., V1) were weaker and more variable. Second, in contrast, multivariate pattern anal...

Introduction: Deep brain stimulation (DBS) is a well-validated treatment of motor symptoms in Parkinson’s disease (PD). While DBS has been used for many years, its mechanism of action remains unclear. With a recent change in labeling that allows MRI to ...

It has been shown that the blood oxygenation level dependent (BOLD) functional MRI signal at magnetic field strengths of ≤ 1.5T arises predominantly from large vessels, which can be quite distant from the sites of neuronal activity. To improve the spatial localization to the active tissues/capillaries, the use of high field magnets has been proposed. To test this hypothesis, we evaluated the microvascular versus the macrovascular contribution to the BOLD response at high fields (4 and 7T) following visual stimulation in humans. Diffusion-weighted BOLD fMRI was used to selectively attenuate the fast-moving (large-vessel) fMRI signals. Two acquisition schemes were used: a gradient-echo scheme which is sensitive to both large- and small-vessel BOLD effects and a spin-echo scheme which should mitigate large-vessel BOLD effects. A comparison was made between the two sets of results. Diffusion-weighted BOLD fMRI was performed on 24 normal humans with graded flow-crushing gradients (4-7 b values). The visual stim...

Growing interest in affective touch has delineated a neural network that bypasses primary somatosensory cortex (S1). Several recent studies, however, have cast doubt on the segregation of touch discrimination and affect, suggesting that S1 also encodes affective qualities. We used functional magnetic resonance imaging (fMRI) and repetitive transcranial magnetic stimulation (rTMS) to examine the role of S1 in processing touch intensity and pleasantness. Twenty-six healthy human adults rated brushing on the hand during fMRI. Intensity ratings significantly predicted activation in S1, whereas pleasantness ratings predicted activation only in the anterior cingulate cortex. Nineteen subjects also received inhibitory rTMS over right hemisphere S1 and the vertex (control). After S1 rTMS, but not after vertex rTMS, sensory discrimination was reduced and subjects with reduced sensory discrimination rated touch as more intense. In contrast, rTMS did not alter ratings of touch pleasantness. Our findings support diver...