Human Brain Mapping via MedWorm.com

Enhanced white matter tracts integrity in children with abacus training

Human Brain Mapping — Wed, 17 Mar 2010 00:00:00 +0100

In conclusion, our findings suggested that long-term AMC training from an early age may improve the memory capacity and enhance the integrity in white matter tracts related to motor and visuospatial processes. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. (Source: Human Brain Mapping)

Overall brain connectivity maps show cortico-subcortical abnormalities in schizophrenia

Human Brain Mapping — Fri, 12 Mar 2010 00:00:00 +0100

Abnormal interactions between areas of the brain have been pointed as possible causes for schizophrenia. However, the nature of these disturbances and the anatomical location of the regions involved are still unclear. Here, we describe a method to estimate maps of net levels of connectivity in the resting brain, and we apply it to look for differential patterns of connectivity in schizophrenia. This method uses partial coherences as a basic measure of covariability, and it minimises the effect of major physiological noise. When overall (net) connectivity maps of a sample of 40 patients with schizophrenia were compared with the maps from a matched sample of 40 controls, a single area of abnormality was found. It is an area of patient hyper-connectivity and is located frontally, in medial an...

Predicting and memorizing observed action: Differential premotor cortex involvement

Human Brain Mapping — Thu, 11 Mar 2010 00:00:00 +0100

Many studies have shown the involvement of the premotor cortex in action observation, recognizing this region as the neural marker of action simulation (i.e., internal modeling on the basis of the observer's own motor repertoire). So far, however, we have remained unaware of how action simulation differs from more general action representation in terms of premotor activation. The present fMRI experiment is the first to demonstrate how premotor structures contribute to action simulation as opposed to other action-related cognitive tasks, such as maintaining action representations. Using similar stimuli, a prediction condition requiring internal simulation of transiently occluded actions was compared to three different action-related control tasks differing solely in task instructions. Resul...

fMRI study of mesial temporal lobe epilepsy using amplitude of low-frequency fluctuation analysis

Human Brain Mapping — Thu, 11 Mar 2010 00:00:00 +0100

Various functional imaging tools have been used to detect epileptic activity in the neural network underlying mesial temporal lobe epilepsy (mTLE). In the present fMRI study, a data-driven approach was employed to map interictal epileptic activity in mTLE patients by measuring the amplitude of low-frequency fluctuation (ALFF) of the blood oxygen level-dependent (BOLD) signal. Twenty-four left mTLE patients and 26 right mTLE patients were investigated by comparing with 25 healthy subjects. In the patients, the regions showing increased ALFF were consistently distributed in the mesial temporal lobe, thalamus, and a few of other cortical and subcortical structures composing a mesial temporal epilepsy network proposed previously, while the regions showing decreased ALFF were mostly located in ...

Basal ganglia hypoactivity during grip force in drug naïve Parkinson's disease

Human Brain Mapping — Thu, 11 Mar 2010 00:00:00 +0100

The basal ganglia (BG) are impaired in Parkinson's disease (PD), but it remains unclear which nuclei are impaired during the performance of motor tasks in early-stage PD. Therefore, this study was conducted to determine which nuclei function abnormally, and whether cortical structures are also affected by early-stage PD. The study also determined if cerebellar hyperactivity is found early in the course of PD. Blood oxygenation level dependent activation was compared between 14 early-stage drug-naïve PD patients and 14 controls performing two precision grip force tasks using functional magnetic resonance imaging at 3 T. The grip tasks used in this study were chosen because both tasks are known to provide robust activation in BG nuclei, and the two tasks were similar except that the 2-s tas...

Diffusion tensor imaging reliably differentiates patients with schizophrenia from healthy volunteers

Human Brain Mapping — Fri, 05 Mar 2010 00:00:00 +0100

The objective of this research was to determine whether fractional anisotropy (FA) and mean diffusivity (MD) maps derived from diffusion tensor imaging (DTI) of the brain are able to reliably differentiate patients with schizophrenia from healthy volunteers. DTI and high resolution structural magnetic resonance scans were acquired in 50 patients with schizophrenia and 50 age- and sex-matched healthy volunteers. FA and MD maps were estimated from the DTI data and spatially normalized to the Montreal Neurologic Institute standard stereotactic space. Individuals were divided randomly into two groups of 50, a training set, and a test set, each comprising 25 patients and 25 healthy volunteers. A pattern classifier was designed using Fisher's linear discriminant analysis (LDA) based on the train...

Electrophysiology meets fMRI: Neural correlates of the startle reflex assessed by simultaneous EMG-fMRI data acquisition

Human Brain Mapping — Thu, 04 Mar 2010 00:00:00 +0100

The startle reflex provides a unique tool for the investigation of sensorimotor gating and information processing. Simultaneous EMG-fMRI acquisition (i.e., online stimulation and recording in the MR environment) allows for the quantitative assessment of the neuronal correlates of the startle reflex and its modulations on a single trial level. This serves as the backbone for a startle response informed fMRI analysis, which is fed by data acquired in the same brain at the same time. We here present the first MR study using a single trial approach with simultaneous acquired EMG and fMRI data on the human startle response in 15 healthy young men. It investigates the neural correlates for isolated air puff startle pulses (PA), prepulse-pulse inhibition (PPI), and prepulse facilitation (PPF). We...

The envious brain: The neural basis of social comparison

Human Brain Mapping — Thu, 04 Mar 2010 00:00:00 +0100

Humans have a drive to evaluate themselves by examining their abilities and outcomes in comparison to others. The present study examined the emotional and neural correlates of upward social comparison (comparison with those who have more) and downward social comparison (comparison with those who have less). Two experiments were conducted with volunteers in an interactive game of chance, in which a putative player won or lost more money than the participant. The results showed that even when participants lost money, they expressed joy and schadenfreude (gloating) if the other player had lost more money. On the other hand when they actually won money, but the other player had won more they expressed envy. This pattern was also demonstrated in a differential BOLD response in the ventral stria...

Disorder-specific inferior prefrontal hypofunction in boys with pure attention-deficit/hyperactivity disorder compared to boys with pure conduct disorder during cognitive flexibility

Human Brain Mapping — Thu, 04 Mar 2010 00:00:00 +0100

Conclusions. The findings extend previous evidence for disorder-specific underactivation in patients with ADHD compared to patients with CD in inferior prefrontal cortex during tasks of inhibitory control to the domain of cognitive flexibility. Inferior prefrontal underactivation thus appears to be a disorder-specific neurofunctional biomarker for ADHD when compared with patients with CD. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. (Source: Human Brain Mapping)

Somatosensory-evoked cortical activity in spastic diplegic cerebral palsy

Human Brain Mapping — Thu, 04 Mar 2010 00:00:00 +0100

Somatosensory deficits have been identified in cerebral palsy (CP), but associated cortical brain activity in CP remains poorly understood. Functional MRI was used to measure blood oxygenation level-dependent (BOLD) responses during three tactile tasks in 10 participants with spastic diplegia (mean age: 18.70 years, SD: 7.99 years; 5 females) and 10 age-matched controls (mean age: 18.60 years, SD: 3.86 years; 5 females). Tactile stimulation involved servo-controlled translation of smooth or embossed surfaces across the right index finger pad; the discrimination tasks with embossed surfaces involved judging whether (1) paired shapes were similar or different, and (2) a rougher set of horizontal gratings preceded or followed a smoother one. Velocity and duration of surface translation was id...

Cortical activation by tactile stimulation to face and anterior neck areas: An fMRI study with three analytic methods

Human Brain Mapping — Thu, 04 Mar 2010 00:00:00 +0100

In conclusion, the sensory cortical representation area of the anterior neck region was mainly at the junction of hand and face representation area and the activated area was larger when the right face or neck was stimulated. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. (Source: Human Brain Mapping)

How much are clinical fMRI reports influenced by standard postprocessing methods? An investigation of normalization and region of interest effects in the medial temporal lobe

Human Brain Mapping — Thu, 04 Mar 2010 00:00:00 +0100

Recent evidence has indicated that standard postprocessing methods such as template-based region of interest (ROI) definition and normalization of individual brains to a standard template may influence final outcome of functional magnetic resonance imaging investigations. Here, we provide the first comprehensive investigation into whether ROI definition and normalization may also change the clinical interpretation of patient data. A series of medial temporal lobe epilepsy patients were investigated with a clinical memory paradigm and individually delineated as well as template-based ROIs. Different metrics for activation quantification were applied. Results show that the application of template-based ROIs can significantly change the clinical interpretation of individual patient data. This...

Decreased neuronal activity in reward circuitry of pathological gamblers during processing of personal relevant stimuli

Human Brain Mapping — Wed, 17 Feb 2010 00:00:00 +0100

Pathological gamblers impress by an increasing preoccupation with gambling, which leads to the neglect of stimuli, interests, and behaviors that were once of high personal relevance. Neurobiologically dysfunctions in reward circuitry underlay pathological gambling. To explore the association of both findings, we investigated 16 unmedicated pathological gamblers using an fMRI paradigm that included two different tasks: the evaluation of personal relevance and a reward task that served as a functional localizer. Pathological gamblers revealed diminished deactivation during monetary loss events in some of our core reward regions, the left nucleus accumbens and the left putamen. Moreover, while pathological gamblers viewed stimuli of high personal relevance, we found decreased neuronal activit...

The volatility of the amygdala response to masked fearful eyes