The human parahippocampal cortex (PPH) is largely coincident with areas TH and TF of von Bonin and Bailey (1951). PPH in the non-human primate is related to visuospatial, visual and auditory information, and is one the main links in memory circuitry through projections to the entorhinal cortex and the CA1/Subiculum border. PPH lies at the caudal part of the parahippocampal gyrus. PPH borders are macroscopially indistinct, rostrally with perirhinal cortex (BA 35 and 36), and caudally with visual association areas (area TEO and V5). PPH medial border is the hippocampal fissure (or parieto-occipital fissure caudally); the lateral border is the collateral and occipito-temporal sulci. Structurally, PPH is mesocortex interposed between the parasubiculum or presubiculum and visual association cortex. The correlation with MRI features (taken on a Phillips Intera 1.5 T machine, 256x512 matrix, 2 mm thick sections with no interval between adjacent sections)allows the delimitation of PPH, based on coronal sections or...

Investigation of somatosensory processing with functional neuroimaging requires precise control of the tactile stimulus. Accordingly, we have developed an MRI compatible, automated tactile stimulator whose surface moves across the subject's finger with or without superimposed vibration. It allows control of the stimulus pattern and orientation, scanning velocity, application force, stimulus duration, and amplitude and frequency of superimposed vibration. The device consists of a drum attached to a lead screw which is turned by a servomotor. The movement of the surface of the drum can be varied from 1-20 mm/s. The finger is lowered onto the drum by an automated pivot device with variable force. As the drum advances axially, the finger's path over the cylinder is a spiral. The tactile stimuli are patterns embossed on acrylic sheets which are bonded to the drum's surface. Through a process of commercial flexography, the embossed patterns can have any desired relief and form. Furthermore, axially directed vibr...

Previously we demonstrated that the +BOLD signal is not sufficiently localized to view structures such as orientation domains in visual cortex. We now asked whether signals based on cerebral blood flow (CBF) could provide better spatial resolution. In the anesthetized cat, we measured CBF and neuronal responses subsequently at corresponding sites from the same animal. Visual stimuli consisted of high-contrast square-wave moving gratings of four orientations, 0.15 cyc/deg, 2Hz. MR parameters were: 4.7T / 31cm, 15-G/cm, 64x64 matrix; single-shot EPI, 2x2cm FOV, 2 mm thickness, TE/TR = 31ms / 0.5s. Before MRI, the visual cortex was exposed (area 18, AP3=center). A MR-transparent grid and surface RF coil were mounted on the skull. Grid holes were filled with MR-opaque agar, and imaged for precise registration of recording sites with CBF maps. Single-unit responses were obtained for 20 cells in 2 hemispheres. The power spectrum of single-orientation CBF maps showed a peak at 973 microns (as expected for orienta...

In vivo imaging of specific molecular processes across whole brains could lead to earlier diagnosis of neurological diseases, more effective drug evaluation, and advances in basic neurobiology, but molecular imaging techniques are constrained by limitat...

Incidental findings on brain MRI - i.e., brain abnormalities discovered in subjects recruited to research studies as healthy controls or unexpected findings in patients - has garnered significant attention in the literature recently. Suspicious brain abnormalities have been reported to occur in as many as 40% of research participants, with clinically significant findings occurring in 2-8% of children and adults. We surveyed members of the MRI research community to document protocols used for discovering and disclosing such findings in research subjects. The cohort comprised investigators who conduct both structural and functional MRI studies. 84% of the investigators (N=31 to date) who responded to the survey reported discoveries of incidental findings on their studies. Findings ranged in severity from those requiring routine follow-up to those requiring immediate or urgent follow-up, and were detected by both MD-trained and non-MD-trained research personnel, including PhD investigators, professional labor...

Introduction - The dopamine transporter protein (DAT) is responsible for pre-synaptic uptake of dopamine (DA). This protein is not, however, stably expressed but can undergo dynamic internalization or surface expression in response to drugs such as coca...

Lack of conditioned fear seems to be one of the main factors underlying antisocial behavior and psychopathy. Brain structures and mechanisms involved in excessive fear in 5 social phobics and lack of fear in 4 emotionally detached psychopaths with extensive criminal records were compared with 7 matched healthy controls in a classical conditioning paradigm using functional magnetic resonance imaging (fMRI). Two slightly different neutral faces served as CS+ or CS- and painful mechanical pressure stimuli as US. Imaging was performed using a 1.5 T whole body MRI system (SPM 99b). Psychopaths showed no activation of anterior cingulate, insular cortex and orbitofrontal cortex, areas that are important in the processing of emotional stimuli.They also revealed reduced amygdala activation to the CS+ during acquisition. The social phobics demonstrated excessive activation of orbitofrontal cortex to both faces during habituation as well as acquisition. Amygdala and insular cortex showed higher activation to CS+ than...

Although the components of the cerebral network mediating saccade preparation in humans have been extensively outlined by numerous functional magnetic resonance imaging (fMRI) studies (e.g., [Schluppeck et al., 2006][1]; [Curtis and Connolly, 2008][2]), the fine temporal and spectral dynamics of its

The primary somatosensory cortex (S1) can be subdivided cytoarchitectonically into four distinct Brodmann areas (3a, 3b, 1, and 2), but these areas have never been successfully delineated in vivo in single human subjects. Here, we demonstrate the functional parcellation of four areas of S1 in individual human subjects based on high-resolution functional MRI measurements made at 7 T using vibrotactile stimulation. By stimulating four sites along the length of the index finger, we were able to identify and locate map reversals of the base to tip representation of the index finger in S1. We suggest that these reversals correspond to the areal borders between the mirrored representations in the four Brodmann areas, as predicted from electrophysiology measurements in nonhuman primates. In all subjects, maps were highly reproducible across scanning sessions and stable over weeks. In four of the six subjects scanned, four, mirrored, within-finger somatotopic maps defining the extent of the Brodmann areas could be...

Traumatic Brain Injury (TBI) is one of the most common, yet neglected, pediatric health issues in North America. Specifically, individuals who experience repetitive mild TBI (RmTBI) generally exhibit poorer developmental outcomes. Some possible causes f...