Are different languages anatomically segregated in the brains of some proficient bilinguals? Behavioral and neuropsychological studies of this question have produced conflicting results. One early functional magnetic resonance imaging (fMRI) study [Kim et al., 1997, Nature 388:171] reported significant segregation between languages in Broca's area when late bilinguals performed an open-ended language production task. Subsequent fMRI studies, utilizing more state-of-the-art methods, have failed to find evidence of such segregation, but these studies also used more constrained linguistic tasks (typically comprehension tasks). We report the results of an fMRI experiment utilizing Kim et al.'s (1997) silent production task, but using state-of-the-art methods. Eight right-handed, proficient, late bilinguals participated in three conditions during a blocked, fMRI experiment: (1) silent, open-ended production in their first language (L1), (2) silent, open-ended production in their second language (L2), and (3) fi...

Early detection of Alzheimer’s disease (AD) symptoms enables treatment strategies based on slowing disease progression. However, despite recent efforts and significant progress, reliable detection of pre-symptomatic and prodromal AD remains a major chal...

We used manganese-enhanced magnetic resonance imaging (MEMRI) to evaluate the activation of different brain regions in females that did not and that paced the sexual interaction. Female rats were divided in four groups: 1) control, 2) exposed to a male ...

Magnetic resonance imaging and computer image analysis in human clinical studies effectively identify abnormal neuroanatomy in disease populations. As more mouse models of neurological disorders are discovered, such an approach may prove useful for translational studies. Here, we demonstrate the effectiveness of a similar strategy for mouse neuroscience studies by phenotyping mice with the cerebellar deficient folia ( cdf ) mutation. Using in vivo multiple-mouse magnetic resonance imaging for increased throughput, we imaged groups of cdf mutant, heterozygous, and wild-type mice and made an atlas-based segmentation of the structures in 15 individual brains. We then performed computer automated volume measurements on the structures. We found a reduced cerebellar volume in the cdf mutants, which was expected, but we also found a new phenotype in the inferior colliculus and the olfactory bulbs. Subsequent local histology revealed additional cytoarchitectural abnormalities in the olfactory bulbs. This demonstra...

Chronification of pain potentially involves pathological modification of the descending pain inhibitory system (DPIS). We examined cerebral substrates of such modification by functional magnetic resonance imaging (fMRI) and a thermal stimulation paradig...

Resting state networks (RSNs) are increasingly forwarded as candidate biomarkers for neuropsychiatric disorders. Such biomarkers may provide objective measures for evaluating novel therapeutic interventions in nonhuman primates often used in translational neuroimaging research. This study aimed to characterize the RSNs of awake squirrel monkeys and compare the characteristics of those networks in adolescent and adult subjects. Twenty-seven squirrel monkeys ( n =12 adolescents [6 male/6 female] ∼2.5 years and n =15 adults [7 male/8 female] ∼9.5 years) were gradually acclimated to awake scanning procedures; whole-brain fMRI images were acquired with a 9.4 Tesla scanner. Group level independent component (ICA) analysis (30 ICs) with dual regression was used to detect and compare RSNs. Twenty ICs corresponding to physiologically meaningful networks representing a range of neural functions, including motor, sensory, reward, and cognitive processes were identified in both adolescent and adult monkeys. The reprod...

Childhood sexual abuse is a major public health problem, however little is known about the effects of abuse on brain structure or function. Animal studies have shown that stressors similar to childhood abuse result in damage to the hippocampus, a brain area involved in learning and memory, and our group and others have reported smaller hippocampal volume measured with magnetic resonance imaging (MRI) and deficits in hippocampal-based verbal declarative memory (recall of a paragraph) in patients with abuse-related PTSD. The purpose of this study was to compare hippocampal volume measured with MRI and hippocampal function during declarative memory tasks (encoding of a paragraph) measured with positron emission tomography (PET), in 33 women, including women with early childhood sexual abuse and PTSD, women with early abuse without PTSD, and women without early abuse or PTSD. A failure of left hippocampal activation during memory tasks was seen in PTSD relative to abused non-PTSD women (F=14.94; df=1,20; p<.00...

The pattern and role of brain plasticity in stroke recovery has been incompletely characterized. Both ipsilesional and contralesional changes have been described, but it remains unclear how these relate to functional recovery. Our goal was to correlate brain activation patterns with tissue damage, hemodynamics, and neurologic status after temporary stroke, using functional magnetic resonance imaging (fMRI). Transverse relaxation time (T2)-weighted, diffusion-weighted, and perfusion MRI were performed at days 1 ( n = 7), 3 ( n = 7), and 14 ( n = 7) after 2 hr unilateral middle cerebral artery occlusion in rats. Functional activation and cerebrovascular reactivity maps were generated from contrast-enhanced fMRI during forelimb stimulation and hypercapnia, respectively. Before MRI, rats were examined neurologically. We detected loss of activation responses in the ipsilesional sensorimotor cortex, which was related to T2 lesion size ( r = −0.858 on day 3, r = −0.979 on day 14; p < 0.05). Significant activation...

Introduction: Mouse models have been widely used in neuroscience research. To examine morphological phenotypes or to perform stereotaxic operations, it is important to have accurate anatomical knowledge of the brain structures inside the opaque skull. M...

An internal model is a neural mechanism that can mimic the input–output properties of a controlled object such as a tool. Recent research interests have moved on to how multiple internal models are learned and switched under a given context of behavior. Two representative computational models for task switching propose distinct neural mechanisms, thus predicting different brain activity patterns in the switching of internal models. In one model, called the mixture-of-experts architecture, switching is commanded by a single executive called a “gating network,” which is different from the internal models. In the other model, called the MOSAIC ( MO dular S election A nd I dentification for C ontrol), the internal models themselves play crucial roles in switching. Consequently, the mixture-of-experts model predicts that neural activities related to switching and internal models can be temporally and spatially segregated, whereas the MOSAIC model predicts that they are closely intermingled. Here, we directly ex...