Linguistic processing is a complex skill with several dissociable components, including semantic, phonological, and syntactic processing. The goal of the present study was to compare and contrast the patterns of cortical activity associated with each of these processes. Twelve healthy young adults were scanned while performing match-to-sample tasks meant to elicit three different types of language processing. The semantic task required choosing a synonym, the phonological task required choosing a rhyme from among two words ending with the same sequence of letters, and the syntactic task required choosing a verb to agree in number with a singular or plural noun. Each of these tasks was compared to a control task of choosing an identical match in an alternating block sequence. Thus the format of the stimulus and the format of the response remained constant across all conditions, and only the linguistic basis of the decision varied. Imaging was performed using a 1.5 T whole-body MRI scanner with a full head c...

E. P. became profoundly amnesic in 1992 after viral encephalitis, which damaged his medial temporal lobe bilaterally. Because of the rarity of such patients, we have performed a detailed neuroanatomical analysis of E. P.'s lesion using magnetic resonance imaging, and we have assessed his cognitive abilities with a wide range of neuropsychological tests. Finally, we have compared and contrasted the findings for E. P. with the noted amnesic patient H.M, whose surgical lesion is strikingly similar to E. P.'s lesion.

Introduction In this work we investigate how the hemodynamic changes evoked by D-amphetamine in normal and MPTP treated monkeys can be mapped using pharmacologic MRI (phMRI) and PET to validate the degree of dopaminergic denervation after MPTP treatment. Methods Macaca Fascicularis: 6 normal control monkeys and 3 MPTP treated monkeys (2 with minor and 1 with severe PD symptoms). MRI phMRI images of cerebral blood volume changes were collected on a Siemen's 3T allegra system for 60-120 minutes (50sec/image set). 1.5-2.5mg/kg amphetamine was used to probe dopaminergic function. PET 11C-CFT was used to assess the binding potential of the dopamine transporter protein (DAT) in the striatum. Results Administration of amphetamine to control monkeys produced strong phMRI activation in caudate, putamen, accumbens, thalamus, and substantia nigra (increase in CBV between 10-35%). There was much less cortical activation compared to our prior rat phMRI studies. For the MPTP-treated monkeys with minor symptoms and moder...

Attention-Deficit Hyperactivity Disorder (ADHD) is the most common psychiatric disorder among school-aged children, occurring in about 5% of the population. Between 40-70% of these children also portray a persistent pattern of antisocial behavior, referred to as Conduct Disorder (CD). Researchers using MRI to study children with ADHD have consistently attributed core deficits of inattention and impulsivity to frontal-striatal-cerebellar abnormalities; however, no study has investigated the neuroanatomical characteristics of children diagnosed with ADHD co-morbid with CD. This study examined a community sample of 12 children with ADHD (aged 8-12, 7 with CD) and 24 healthy controls matched for age, sex, handedness, and SES. Volume measurements, including right-left asymmetries, were quantified from MRI of the total brain and cerebellar vermis. No significant differences in brain size or asymmetry were found between the groups. Measurements of the left and total posterior superior and inferior lobes of the ve...

Tic disorders (TD) are characterized by the presence of motor and/or vocal tics. Common neurophysiological frameworks suggest dysregulations of the cortico-striatal-thalamo-cortical (CSTC) brain circuit that controls movement execution. Besides common tics, there are other “non-tic” symptoms that are primarily related to sensory perception, sensorimotor integration, attention, and social cognition. The existence of these symptoms, the sensory tic triggers, and the modifying effect of attention and cognitive control mechanisms on tics may indicate the salience network's (SN) involvement in the neurophysiology of TD. Resting-state functional MRI measurements were performed in 26 participants with TD and 25 healthy controls (HC). The group differences in resting-state functional connectivity patterns were measured based on seed-to-voxel connectivity analyses. Compared to HC, patients with TD exhibited altered connectivity between the core regions of the SN (insula, anterior cingulate cortex, and temporopariet...

3-NP, a succinate dehydrogenase inhibitor, is widely used as an experimental model to study HD, energy metabolism and cell death. We used a rat model to investigate 3-NP induced acute and prolonged neurotoxicity using in vivo imaging of cerebral glucose utilization (CGU)and dopamine receptors by PET, neuroanatomy by MRI and neurochemicals by MRS. 3-NP was administered (male Spraque-Dawley) twice a day (10 mg/kg ip.) until symptomatic or max of 5 days. PET studies of CGU were conducted daily using a super high resolution (1.3x1.3x1.8 mm3) in-house built PET device. MRI and MRS studies were conducted with a GE Omega 4.7 T imager. Studies of CGU showed significant interanimal variation in the acute response of toxin, similar to motor activity. The average decrease of CGU in the lesions was 31+/-12% and the lesions started to develop on the first day of 3-NP. Four weeks later CGU was recovered to -13+/-5% and then in 3 months decreased again to –48+/-10%. Dopamine D1 and D2 receptors showed progressively decre...

Introduction: Mesopontine tegmental nuclei, such as the cuneiform (CnF), pedunculotegmental (PTg, or “pedunculopontine”), oral pontine reticular (PnO, or “pontis oralis”), paramedian-raphe (PMnR) and caudal-linear-raphe (CLi) nuclei, are crucial for aro...

Research published in eNeuro emphasizes real-time eye contact as basis for effective social interaction.

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...

During adolescence, the dopaminergic system in the brain is undergoing dramatic processing that includes synaptic pruning and alteration in dopaminergic receptor numbers. We used phMRI to investigate the differences in neuronal responses to acute cocaine challenge in the adolescent and adult brain. Methods – Adolescent (22 days old, P22, n=7) and adult (>60 days old, n=6) Sprague-Dawley rats were used in this study. Rats were scanned in a 9.4T Bruker scanner under 1% halothane anesthesia with an acute cocaine challenge (0.5mg/kg, i.v.). Regional cerebral blood volume (rCBV) changes were assessed by using IRON method with echo planar imaging sequence (TR/TE 10ms/6ms). Dopamine (DA) release by microdialysis was assessed in the caudate/putamen in a separate group of P22 rats. Results – Cocaine challenge on the adult rats induced bi-phasic rCBV changes (negative followed by positive rCBV changes) in the caudate/putamen (CPU), Nucleus accumbens (NAc), medial prefrontal cortex (mPFC), and thalamus. Cocaine chall...