Cerebral activation in response to contact heat stimulation of the hindpaw was observed in functional magnetic resonance imaging (fMRI) experiments in isoflurane anesthetized rats. Cingulate-, sensory-motor-, and insular cortex, as well as medial and lateral posterior thalamic nuclei, hypothalamus and periaqueductal gray were the most consistently, often bilaterally activated regions. Subcutaneous zymosan injection into one hindpaw led to inflammation and hyperalgesia resulting in activity changes in the namely CNS structures. When the contact heat stimulus was applied after initiating inflammation the hyperalgesia manifested itself as a significant increase of the size of activated areas and/or functional blood oxygenation level dependent (BOLD) signal amplitude in the mentioned brain regions. These changes developed over time and are due to peripheral and central sensitization. Our results indicated that processes of sensitization in the cerebrum led to significant increases not only after stimulation of...

Transcranial magnetic stimulation (TMS) is a brain stimulation technique that involves passing a powerful and rapidly changing current through a coil that is placed on the scalp. The induced magnetic field passes unimpeded through the skull and transiently disrupts neural circuitry. TMS is an emerging technology which is being used to investigate a wide range of behavioral phenomena, including motor control, visual processing and memory. Although functional MRI guidance and infrared tracking have improved the localization of TMS, the strength and distribution of the induced magnetic fields have not yet been accurately characterized. To localize the magnetic field of a 110mm double-cone TMS coil, we imaged a water-filled spherical phantom with TMS application in 3 orthogonal planes in a 0.5 T open MR scanner. A standard 2D fast gradient echo sequence was used to obtain images of phase evolution due to application of a constant 50 mA current to the TMS coil (TE = 7.8 and 8.8 ms, TR = 150 ms, voxel size ~ 3 m...

MDMA, or Ecstasy, is a widely used recreational drug with potent effects on cognition and behavior and possible long term effects on brain function, chemistry, and anatomy. Recent MRI studies have looked at CBF changes, NAA levels, and tissue diffusion changes in human MDMA users. In this experiment, conscious marmosets were acclimated to the MRI and imaged in a restrainer (Insight Neuroimaging Sys.) in a 4.7T MRI (Bruker). The initial period of drug uptake was imaged while evoked sensory activity was assessed prior to, and following oral MDMA (1mg/kg). Globally, BOLD signal decreased after drug administration. Activations were seen after 20-40 minutes in dopaminergic/serotonergic regions of the brain, chiefly: caudate, putamen, globus pallidus, and nucleus accumbens. Preliminary data suggest that visual activations were slightly lower after MDMA while somatosensory activations remained consistent (see figure). No major changes in respiratory physiology were noted during the experiment. Initial findings su...

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...

Histologic methods has long been used to examine tissues /organ systems for potential morphologic changes. However, the detailed examination of structures such as axon tracks, which can exhibit complex three-dimensional (3D) morphologies and cover significant distances, can be difficult to accurately determine using these methods. In order to gain a clearer understanding of morphologic ramifications which may occur following random or targeted genetic modification of specific murine lineages, we are developing MRI scanning and data analysis protocols which allow us to determine, in a relatively high throughput manner, changes in neural tracts within the murine CNS. In order to determine the practical limits of morphologic resolution using these MRI scanning and analysis protocols, we examined several axon guidance mutants previously characterized in our laboratory. The mutants examined represent members of the EphB family of receptor tyrosine kinases. T2 weighted multiple spin-echo images (TR 1500 ms, TE 3...

Monkeys have been used widely to model human neurobiological and cognitive development. To examine early brain development a group of eight Rhesus monkeys (Macacca mulatta) were scanned repeatedly from the ages of 1 wk to 5 yrs on a GE 1.5 T Signa MR scanner. Each monkey received 8-20 (mean 14) whole brain T1-weighted structural scans in the horizontal plane using a 3-D volume SPGR pulse sequence (FOV 110 mm; slice thickness 1mm). An additional 8 adult monkeys were scanned to increase the number of cases at ages 36 and 60 months. Using the MedX image analysis program skull and extracranial structures were removed and the brain volumes calculated by two independent observers (inter-observer reliability r=0.84, p< 0.001). Total brain volumes at 1 week, 1, 2, 3, 4, 5-6, 8, 12, 18, 24, 36 and 60 months were analyzed by ANOVA with repeated measures resulting in a significant effect of age (F=50.8, p (corrected)< 0.001). Brain volumes showed a significant increase from 1 week to 2 years of 59% with no significan...

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...

We aimed to identify brain areas involved in responding to affect communicated by expressive piano performance. Our subjects listened to two versions of Chopin’s Etude in E major, Opus 10, No. 3. The first version was an expressive performance, recorded by a highly trained musician on a computer-monitored piano. Our control was a computer-generated, mechanical performance of the same composition. Data analysis revealed differential brain activation in the two listening conditions. The expressive performance elicited greater activation in anterior cingulate, right temporal pole, right inferior frontal gyri, inferior parietal lobe and superior temporal gyri, areas that have been associated with emotion, attention and speech perception. The mechanical performance elicited greater activation in cerebellum, supplementary motor area and dorsolateral prefrontal cortex, areas primarily involved in motor and sequencing tasks. Our observations suggest that expressive music performance communicates affect beyond the ...

BOLD fMRI is often used to map the locations of brain activity. Analysis of BOLD data typically identifies volumes of activation by mapping where BOLD signals are temporally correlated to task performance. This procedure does not distinguish between volumes located near the origin of activation and those in remote veins and sinuses. In order to separate BOLD signals in large veins and sinuses from signals in the parenchyma, we collected images of the brain’s venous system and used these to create vascular masks. Functional and vascular data sets were co-registered, and the skull was extracted from the images. BOLD signal correlations to a reference function were calculated for each voxel, and voxels with a correlation coefficient of 0.6 or greater were used to create an activation mask. A vascular mask was created from the 2.8% most intense brain voxels in the venogram, which approximates the amount of venous cerebral blood volume. This voxel-selection method is independent of the absolute intensity values...