We suspect that differences in apparent diffusion coefficient (ADC) between two models of ischemia (middle cerebral arterial occlusion, MCAO, and photo-thrombosis, PT) could be detected with MRI, using MAP2 IR to confirm the extent of the infarct. Nine Sprague-Dawley rats under isoflurane anesthesia and controlled ventilation were subjected to either MCAO combined with bilateral common carotid artery occlusion (n=6) or cortical PT (n=3). MRI was used to generate ADC trace (ADCtr), pefusion (spin-labeling, CBF), and T1 images. After 3.5±0.3 hr (mean±sem), the brain was immersion fixed and processed for MAP2 IR to HM2 (Sigma) antibody. The stained section in the same coronal plane as the MR images was digitized and aligned with the ADCtr, CBF, and T1 images using the AIS/C imaging system. Four regions-of-interest were chosen: the ischemic core (IC), cortex immediately adjacent (ischemic border, IB), and homologous regions in the opposite hemisphere including normal cortex (NC), guided by the lesion area from...

Object Incidence of silent microbleeds (MBs) in patients with moyamoya disease (MMD) was investigated using 3-tesla (3T) MR unit. Methods We retrospectively examined incidence of silent MBs in twenty-five patients among 63 patients hospitalized with MMD between 1999 and 2004 by gradient-echo T2*-weighted images using 3-tesla (3T) and 1.5T MR units. There were five men and twenty women, ranging in age from 17 to 66 years old (mean 41+14 years old). Eighteen patients were diagnosed with ischemic MMD and seven patients with hemorrhagic MMD. Incidence of MBs was also evaluated with the same 3T MR unit in thirty-four healthy volunteers including seven men and twenty-seven women, ranging in age from 18 to 71 years old (mean 33+12 years old). Silent MBs could be fond in eleven patients (44 %) by 3T MR unit, while they were detected in seven patients (28%) by1.5T unit. At the 3T study of the healthy individuals, MBs were found in two patients (5.8%). Incidence of MBs was significantly higher in the patients with M...

This study assessed, via fMRI, changes in cortical activity during a training session with Functional Electrical Therapy (FET) - a rehabilitative therapy that combines voluntary activation with patterned Functional Electrical Stimulation of muscles (FES). Five able bodied subjects participated in this study. Each subject was instrumented with surface stimulation electrodes positioned over motor points of the finger flexor/extensors muscles on the right arm. A button press with the left index finger initiated patterned electrical stimuli (50 Hz, 200 ìs pulse duration, 8-15 mA pulse amplitude) to produce right hand opening and closing. Right index finger flexion/extension was recorded with a goniometer. Subjects were scanned in a 3T GE scanner using standard fMRI methods in a randomized block design paradigm with 5 different conditions: rest, voluntary activation (VA), imagined movement, FES, and FET. Each task lasted 30 s and repeated 5 times. Data were realigned, smoothed and normalized using standard proc...

Several functional areas are proposed to reside in human lateral occipitotemporal cortex, including the motion-selective human homolog of macaque area MT (hMT), object-form-selective lateral occipital complex (LO), and body-selective extrastriate body area (EBA). Indeed, several functional magnetic resonance imaging (fMRI) studies have reported significant activation overlap among these regions. The standard interpretation of this overlap would be that the common areas of activation reflect engagement of common neural systems. Alternatively, motion, object form, and body form may be processed independently within this general region. To distinguish these possibilities, we first analyzed the lateral occipitotemporal responses to motion, objects, bodies, and body parts with whole-brain group-average analyses and within-subjects functional region of interest (ROI) analyses. The activations elicited by these stimuli, each relative to a matched control, overlapped substantially in the group analysis. When hMT, ...

Tactile-visual cross-modal plasticity due to visual deprivation has been reported. Whether this is solely due to visual deprivation or with any long-term tactile training is not yet determined, particularly in the primary visual cortex (V1). If tactile learning by the sighted subjects induces activation of the visual cortex by the tactile tasks, the latter may be the case. Here we conducted fMRI studies with normal sighted persons who had long been trained by tactile shape discrimination of Mah-Jong tiles with their right thumb (Saito et al., 2003). The tasks were the tactile shape discrimination with Mah-Jong tiles and with Braille characters to which they are naïve. During the scan, two dimensional shape patterns on a plastic tile were presented tactually. Subjects were explored the presented tiles by the right thumb with eyes closed and asked to discriminate the presented pair was same or not. Tactile discrimination with Mah-Jong tile with their right thumb activated the V1 of the well-trained subjects....

Recent work has identified the anterior cingulate cortex (ACC) as a key component in a neural system involved in reinforcement learning and error processing. According to a recent theory, the ACC is activated by the impact of dopaminergic reward prediction signals that are elicited when the basal ganglia detect unexpected response errors or negative feedback (Holroyd & Coles, 2002; Psych Review). This theory suggests that performance errors and negative feedback should give rise to activation of a common area in ACC. To test this prediction, we conducted an fMRI experiment in which participants performed a probabilistic learning task. This task allowed a within-subject comparison of the neural activation associated with speeded response errors and that associated with unpredicted negative feedback. Consistent with our prediction, the results revealed a common area in dorsal ACC that was more active following incorrect responses than following correct responses, and more active following negative feedback t...

A new real-time multi-echo fMRI technique with gradient compensation of susceptibility related signal losses was used to measure activation in amygdala and hippocampus during 60 s trials of self-induced sadness. 9 healthy adults (3 males, 6 females, 22-45 years) performed a validated mood induction paradigm with sad and neutral faces in repeated scans (10 trials each, total trials: 235). This technique enabled online comparison with self-rating of sadness in single trials and immediate feedback of amygdala-hippocampus activation to the subject to reinforce mood induction. Activation of predominantly left amygdala-hippocampus during sad mood induction was observed in all subjects and in 77 % of single trials. This activation does not appear to diminish with repeated mood induction. The linear correlation between the intensity of amygdala-hippocampus activation and self-rating increased with repeated scanning, possibly reflecting adaptation to the mood induction procedure. These results suggest that amygdala...

Of the more than 300 million people diagnosed with depression worldwide, ~30% are classified as treatment-resistant (TRD). This occurs when a person fails to respond to conventional treatments, including a combination of psychotherapy with antidepressan...

Diffusion tensor imaging (DTI) has gained popularity in studying microstructural changes in the spinal cord of patients with degenerative cervical spondylotic myelopathy (CSM). While DTI is sensitive to microscopic pathologies in the injured spinal cord...

The effective connectivity of brain networks can be assessed using functional magnetic resonance imaging (fMRI) to quantify the effects of local electrical microstimulation (EM) on distributed neuronal activity. The delivery of EM to specific brain regions, particularly with layer specificity, requires MRI compatible equipment that provides fine control of a stimulating electrode’s position within the brain while minimizing imaging artifacts. To this end, we developed a microdrive made entirely of MRI compatible materials. The microdrive uses an integrated penetration grid to guide electrodes and relies on a microdrilling technique to eliminate the need for large craniotomies, further reducing implant maintenance and image distortions. The penetration grid additionally serves as a built-in MRI marker, providing a visible fiducial reference for estimating probe trajectories. Following the initial implant procedure, these features allow for multiple electrodes to be inserted, removed, and repositioned with m...