An unresolved question in neuroscience and psychology is how the brain monitors performance to regulate behavior. It has been proposed that anterior cingulate cortex (ACC), on medial surface of frontal lobe, contributes monitoring by detecting errors. In this study, event-related functional magnetic resonance imaging was used examine ACC function. Results confirm region shows activity during erroneous responses. However, also observed same correct responses under conditions increased...

The typical functional magnetic resonance (fMRI) study presents a formidable problem of multiple statistical comparisons (i.e., > 10,000 in 128 x image). To protect against false positives, investigators have typically relied on decreasing the per pixel positive probability. This approach incurs an inevitable loss power to detect statistically significant activity. An alternative approach, which relies assumption that areas true neural activity will tend stimulate signal changes over...

Research suggests that the basal ganglia complex is a major component of neural circuitry mediates reward-related processing. However, human studies have not yet characterized response to an isolated reward, as has been done in animals. We developed event-related functional magnetic resonance imaging paradigm identify brain areas are activated after presentation reward. Subjects guessed whether value card was higher or lower than number 5, with monetary rewards incentive for correct guesses....

This study examines important developmental differences in patterns of activation the prefrontal cortex during performance a Go-No-Go paradigm using functional magnetic resonance imaging (fMRI). Eighteen subjects (9 children and 9 adults) were scanned gradient echo, echo planar response inhibition task. The results suggest four general findings. First, location was not different between adults, which is similar to our earlier pediatric fMRI working memory task (Casey et al., 1995). Second,...

Event-related functional MRI and a version of the Stroop color naming task were used to test two conflicting theories anterior cingulate cortex (ACC) function during executive processes cognition. A response-related increase in ACC activity was present when strategic less engaged, conflict high, but not engaged reduced. This is inconsistent with widely held view that implements reduce cognitive conflicts, such as response competition. Instead, it suggests serves an evaluative function,...

OBJECTIVE: The dorsolateral prefrontal cortex has been implicated in both working memory and the pathophysiology of schizophrenia. A relationship among activity, dysfunction, symptoms schizophrenia not firmly established, partly because generalized cognitive impairments patients task complexity. Using tasks that parametrically manipulated load, authors tested three hypotheses: 1) with differ activity only when behavioral performance differentiates them from healthy comparison subjects, 2)...

Background: Previously we proposed that dorsolateral prefrontal cortex (PFC) supports a specific working memory (WM) subcomponent: the ability to represent and maintain context information necessary guide appropriate task behavior.By context, mean prior taskrelevant represented in such form it selection of behavioral response.Furthermore, hypothesized WM deficits schizophrenia reflect impaired processing due disturbance PFC.We use functional magnetic resonance imaging examine PFC activation...

Abstract Functional magnetic resonance imaging (fMRI) was used to examine the pattern of activity prefrontal cortex during performance subjects in a nonspatial working memory task. Subjects observed sequences letters and responded whenever letter repeated with exactly one nonidentical intervening. In comparison task, monitored similar for any occurrence single, prespecified target letter. scanning performed using newly developed spiral scan image acquisition technique that provides...

Magnetic detection of complex images in magnetic resonance imaging (MRI) is immune to the effects incidental phase variations, although some applications information lost or are degraded. It suggested that synchronous demodulation can be used MRI systems place magnitude provide complete suppression undesired quadrature components, preserve polarity and information, eliminate biases reduction signal-to-noise ratio (SNR) contrast low SNR images. The variations an image removed through use a...

In magnetic resonance imaging, field inhomogeneities cause distortions in images that are reconstructed by conventional fast Fourier transform (FFT) methods. Several noniterative image reconstruction methods used currently to compensate for inhomogeneities, but these assume the map characterizes off-resonance frequencies is spatially smooth. Recently, iterative have been proposed can circumvent this assumption and provide improved compensation effects. However, straightforward...

Functional magnetic resonance imaging (fMRI) was used to examine patterns of cortical activity in children during performance a spatial working memory task. Six (8–10 years) and six adults (19–26 searched linear array four boxes for the appearance dot. In visual blocks, participants made no response. motor were instructed indicate location dot on each trial using button-press at which had appeared 1 or 2 trials previously. Both showed left precentral postcentral gyri, as well right...

Abstract Parallel excitation has been introduced as a means of accelerating multidimensional, spatially‐selective using multiple transmit coils, each driven by unique RF pulse. Previous approaches to pulse design in parallel were either formulated the frequency domain or restricted echo‐planar trajectories, both. This paper presents an approach that is quadratic optimization problem spatial and allows use arbitrary k ‐space trajectories. Compared approaches, new method some important...

Studies of a range higher cognitive functions consistently activate region anterior cingulate cortex (ACC), typically posterior to the genu and superior corpus collosum. In particular, this ACC appears be active in task situations where there is need override prepotent response tendency, when responding underdetermined, errors are made. We have hypothesized that function monitor for presence "crosstalk" or competition between incompatible responses. prior work, we provided initial support...

When time-varying gradients are used for imaging, the off-resonance behavior does not just cause geometric distortion as is case with spin-warp but changes shape of impulse response and causes blurring. This effect well known projection reconstruction spiral k-space scanning sequences. The authors introduce a homogeneity correction method to correct zeroth order effects inhomogeneity using prior knowledge inhomogeneity. In this method, data segmented according collection time, reconstructed...

An experimental lesion in the primary motor or sensory cortices monkeys leads to functional reorganization areas surrounding contralateral homologous regions. In humans, task‐dependent brain activation after stroke seems be multifocal and bilateral. Although many active structures are seen stroke, their roles unclear. For instance, uninjured cortex may play a significant role recovery associated with mirror movements. Other areas, particularly those outside affected middle cerebral artery...

Brain function can be mapped with magnetic resonance (MR) imaging sensitized to regional changes in blood oxygenation due cortical activation. Several MR methods, including conventional and echo-planar imaging, have been successfully used for this purpose. The authors investigated spiral k-space implemented an unmodified 1.5-T clinical imager, of A gradient-echo, method was measure activation the primary visual cortex (number sequence task), motor (fist-clenching prefrontal (verbal fluency...