Epochal developmental events like pregnancy and lactation can alter cortical organization and representation affecting memory, perception and attendant behavior. This study used fMRI to observe cortical activation in conscious, first time mother (primiparous) rats in response to pup suckling vs the general tactile stimulus of mechanical rubbing. Pup suckling and general tactile stimulation over the long hair of the ventrum and hairless skin of the nipples and areolas resulted in a similar pattern of cortical activation in primiparous dams. Ventrum rubbing in virgin females activated the same cortical areas. In addition to the anticipated stimulus-evoked activity in the somatosensory cortex, activation was observed in parietal, motor, temporal, cingulate, retrosplenial, auditory and visual cortices for all stimulus conditions. These activations suggest that the stimuli under these experimental conditions were not modality specific and promoted general arousal across the cortical mantel. Interestingly, the s...

Hippocampal volumetrics are important for studying disease progression and diagnosis of temporal lobe epilepsy, Alzheimer’s disease and schizophrenia. However, comparing volumetric variation across studies is difficult due to differing anatomical boundaries, subject characteristics, statistical analyses and image processing techniques. One approach to this problem is to create a database of the homogeneous aspects of studies to increase uniformity and get comparative results. The Internet Brain Volume Database (IBVD) was created to provide a comparison of the various aspects of volumetric studies. As an example of this approach, the current study evaluates normal ranges of volumes in the hippocampus across published studies with similar manual methods and anatomical boundaries. The purpose was to compare and evaluate region of interest (ROI) methods of volumetric analysis and generate a summary of trends and results. Twenty-two peer-reviewed studies involving ROI measurements of the hippocampus were survey...

The stria of Gennari --a definitive landmark for anatomical identification of primary visual cortex--has been imaged both ex vivo and in vivo and visualized in planar sections, but no surface reconstructions were performed. To image the stria, we used a high-bandwidth, multiecho FLASH pulse sequence with an isotropic voxel size of 200 microns and scanned ex vivo human occipital cortex at 7T for 12 hours. This provided enhanced contrast between gray and white matter and reduced MR image distortion, thus enabling reliable identification of the full extent of the stria. We developed software for reconstructing surfaces from slice images obtained either from MRI or serial tissue section data. This software was used to identify vertices representing points of the stria as input to a surface tiling algorithm, which outputs a two-dimensional, manifold triangular mesh representing the striate surface. A flattened surface was obtained using an accurate quasi-isometric flattening algorithm (see Balasubramanian et al...

The goal of this study was to use functional imaging to examine cortical plasticity and to identify neuronal activity changes in the network level after peripheral nerve injury. High resolution functional Magnetic Resonance Imaging (fMRI) has emerged as an important tool to study brain plasticity in humans and rodents in a non-invasive manner. In order to detect cortical reorganization, we have applied the common sciatic and the saphenous (the main nerves innervating the hindlimb) nerves injury model in rats, which was previously shown to induce short- as well as long-term intra-cortical plasticity changes at the cellular and at the network level. At different time points after surgery, fMRI was performed on an 11.7T animal MRI system on sham-operated rats, on sciatic nerve cut rats, and on rats where both the sciatic and saphenous nerves were cut. Electrical stimulation of the healthy hindlimb in the sham-operated and in the sciatic nerve cut rat groups resulted in normal contra-lateral somatosensory cort...

Memories vary in their durability even when encoding conditions apparently remain constant. We investigated whether, under these circumstances, memory durability is nonetheless associated with variation in the neural activity elicited during encoding. Event-related functional magnetic resonance imaging data were acquired while volunteers semantically classified visually presented words. Using the “remember/know” procedure, memory for one-half of the words was tested after 30 min and for the remaining half after 48 h. In several regions, including left hippocampus and left dorsal inferior frontal gyrus (IFG), activity at encoding differed depending on whether items were later recollected regardless of study-test delay. Delay-selective effects were also evident, however. Recollection after 48 h was associated with enhanced activity in bilateral ventral IFG, whereas recollection after 30 min was associated with greater fusiform activity. Thus, there is a relationship between the neural activity elicited by an...

Periodic breathing is associated with substantial alterations in autonomic outflow and extreme heart rate variation that accompany the cessation and resumption of respiratory efforts. The breathing pattern provides an opportunity to determine neural structures recruited to initiate and terminate breathing efforts, and to assess sites involved in mediating sympathetic and parasympathetic outflow. We examined signal changes in neural sites during periodic breathing in quiet sleep in two patients with obstructive sleep apnea. Twenty-five volumes of 20 image slices through the brain (Echo Planar technique) were collected using a GE 1.5T Signa scanner during a 2.5 min period of quiet sleep as determined by MR-compatible EEG techniques. The images were corrected for slice timing and motion, and were spatially and intensity normalized. Correlations between breathing rate and signal intensity were calculated, and significant voxels overlaid onto T1 anatomical images. During apneic periods, both patients showed sig...

In vivo assessment of stem cell transplantation by MRI will allow the evaluation of indirect markers of graft effects over time. Current clinical evaluation of fetal tissue transplants is achieved using a battery of behavioural and neuroimaging techniques. Application of neuroimaging techniques to stem cell grafts will be more problematical due to the diffuse nature of graft integration caused by cell migration into the host parenchyma. Therefore, more sensitive neuroimaging methods need to be developed to assess the effects of such cells in the clinical domain. Using serial T1, T2, T2* and proton density weighted MRI scans at 2 days pre-grafting and 2, 7, 14 and 56 days post-grafting we have measured the effects of unilateral grafting of conditionally immortalised MHP-36 stem cells (2 deposits of 50000 cells in 4μL NAC) on the systemic 3-NPA rat model of Huntington’s disease. Changes relative to pre-grafting in total brain volume, CSF volume and total tissue volume were measured. Temporal evolution of the...

Prior research has shown age-related declines in performance of many complex attentional tasks. Prior neuroimaging studies suggest that increased cognitive task demands and/or reduced processing efficiency in the elderly are often associated with compensatory recruitment of additional brain regions associated with that task. We investigated age-related changes in blood oxygenation level dependent (BOLD) activation using a FMRI divided attention task. A healthy elderly group (ages 65-80)and a younger control group (21-35) were compared on a task requiring shifting of visuospatial attention between global and local levels of complex Navon-type stimuli. Participants identified 4 target numbers that switched between global and local levels at pseudorandom intervals. When comparing this attention-shifting condition to a control condition with sustained visual scanning, a whole-brain analysis indicated BOLD activation in both groups in the visual attention network. These regions included prefrontal and mid-front...

In our study, we examined delayed volume changes in remote brain areas in 8 stroke patients with territorial MCA infarction. MRI scans were carried out 7 days and between 3 and 16 months after stroke. The segmented brain MRIs from the same patient at two different times were matched to each other using an extended principal axes theory, generalized to affine movements, a cross-correlation based procedure and a fast automated multiresolution full-multigrid movement model. This method enables exact alignment and reproducibility due to the completely automated procedure. The investigated brains showed remarkable volume reductions in widespread cortical areas remote from the lesion site. Atrophy was also detected in the ipsilateral thalamus and caudate nucleus that were both not affected by ischemia. Secondary brain atrophy was accompanied by an improved score of the European Stroke Scale at the follow-up examination. Our study demonstrates delayed widespread and locally differential brain atrophy in brain are...

Introduction Microdialysis studies of rats have shown that electrical acupuncture can modulate dopamine (DA) concentrations (1). We conducted an animal imaging study using amphetamine (AMPH) to enhance DA concentration and then apply electrical stimulation (ES) to test the hypothesis that acupuncture may modulate DA tone. Method Pharmacological MRI (phMRI) images were collected on rats as described earlier (2,3). AMPH(3mg/kg ip) was administrated and 20 minutes of ES was followed. ES was applied to 1: Hegu ((Acupoint LI4, dorsum of forepaw), 1mA/2Hz, n=5.) 2. Hegu (5 or 6 mA/2Hz, n=3). 3. Wrist (radial side, s.c., graded current:1, 3, 5mA/2Hz, n=2). Results 1mA current at Hegu strongly attenuated the AMPH induced rCBV increase in frontal cortex, nucleus accumbens, insular cortex and dosolateral striatum. There was no blocking of signal increase on the ventrolateral striatum. 5 or 6mA current at Hegu or the graded current on the wrist had a much smaller blockade effect in most brain areas. Among all of the ...