The urge to use drugs (craving) is an important factor in relapse to drug abuse. In heroin dependent patients, treatment with an opiate agonist(methadone maintenance, MM) is effective in preventing opiate withdrawal symptoms, however some MM patients continue experiencing drug craving. Data indicate that such craving may be a response to conditioned drug-related stimuli. Arterial Spin Labeled (ASL) functional MRI (fMRI) is a perfusion-weighted technique which has practical advantages over both PET and BOLD fMRI for the study of the regional cerebal blood flow (rCBF) changes during sustained cognitive states, such as cue-induced drug craving. In an ongoing study (target N = 20), MM patients (9)and controls (7) viewed non-drug and heroin-related videos (10 min each) while undergoing multi-slice ASL fMRI. Statistical parametric mapping (SPM99) was used to compare rCBF during heroin cues with baseline and correlate refional with subjective and physiological measurements of desire to use opiates. Preliminary an...

Precise definitions of the anatomic subdivisions of the brainstem are required for structural and functional imaging studies of the brainstem. Localization of functional activation is aided by this precise mapping of function onto structure. In addition, brainstem abnormalities may be characterized in terms of their effects on brainstem function and volume. We describe a parcellation system of the human brainstem based upon neuroanatomy and which conserves the topographic uniqueness of the individual brain. METHOD: Based upon a set of topographical landmarks, we have defined a system for parcellation of the human brainstem into well-defined, closed areas or parcellation units (PUs). To this end, 10 delimiting planes were identified. To apply this method to T-1 weighted anatomic MR images, brainstem exterior and peduncular borders were defined, planes were identified using a cross-referential morphometric tool, and brainstem subdivision was performed. The resulting segmentation served as the basis for morph...

The ability to image retinal functions non-invasively and in three dimensions can have numerous potential applications. We explored the feasibility of mapping the retina's responses to visual stimuli in anesthetized cats by using blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI). Functional maps obtained with a spatial resolution of 470x470x1000 mm3 showed increased activity along the retina following visual stimulation (drifting gratings). The BOLD fMRI signal increases ranged from 1.0-2.5% relative to basal (dark) conditions. Hemi-field stimulation studies demonstrated that stimuli presented to the upper half of the visual field stimulated the lower part of the retina, while stimuli presented to the lower half of the visual field stimulated the upper part of the retina, as expected. Multi-slice functional images of the retina were reconstructed and flattened onto a two-dimensional surface. No statistically significant activation was observed around the blind spot. To t...

Repeated listening to a series of sound tracks in the same sequence creates a long-lasting sequential auditory memory. Listening to the end of a track immediately evokes an auditory image of the beginning of the next track. We have studied the functional anatomy of this anticipatory musical imagery with functional magnetic resonance imaging (fMRI). Subjects were screened for the reliability of their anticipatory imagery using sound tracks from their favorite compact disk. Each subject listened to the final 32 sec of each track in random order and was asked to produce the opening bars of the following track. Only subjects who scored above 75% correct were used for further study. Each fMRI scan consisted of nine 40-sec cycles divided into 32 sec of song followed by 8 sec of silence. Each imaging session included six functional scans alternating between familiar and unfamiliar song sets. Activation during silent anticipation of the next track following familiar songs (familiar silence) was compared with that ...

Mild cognitive impairment (MCI) is a term for non-demented individuals with memory complaints and deficits greater than age-adjusted normal performance. Functional MRI (fMRI)may be a more sensitive method than other techniques to reveal functional abnormalities in individuals with MCI, only a proportion of whom progress to Alzheimer’s disease (AD). fMRI images were acquired using single shot spiral imaging. Subjects performed incidental encoding and retrieval tasks for coloured and black & white photographs contrasted to baseline fixation. During encoding subjects were required to make a semantic decision (natural vs. man-made) or a perceptual decision (colour vs. black & white). During retrieval, subjects judged whether they had seen the photographs in the previous encoding conditions. Initial analysis of young healthy adults (n=6) revealed activation in a network of regions in the memory tasks when contrasted to baseline fixation. Semantic encoding engaged a network of regions (fusiform gyrus, parietal, ...

Using a cross-form priming paradigm we have previously shown the extraction of semantic information from pictures, both with and without awareness. We manipulated awareness by using extended presentations (5 sec), as well as brief (approx 50 msec), masked presentations designed to halt conscious processing. Subsequent recognition judgments revealed that information was extracted both with and without awareness. We have now adapted this cross-form paradigm for fMRI. Using the same briefly-presented, masked pictures we demonstrated activation associated with the extraction and encoding of semantic information. Further, by comparing block and event-related designs, we show activation differences for successful and unsuccessful encoding. Results are generally consistent with previous fMRI investigations of encoding. That is, we demonstrate activation in ventral visual cortex, medial frontal cortex, and hippocampal regions. However, key differences also are evident. For example, we did not observe primary visua...

The differential role of the cerebellar cortex and nuclei has rarely been addressed in human lesion and functional brain imaging studies. One important reason is the difficulty of defining the localization of the cerebellar nuclei and extent of possible lesions based on CT or MR scans. The present MRI investigation was specifically designed to study the detailed anatomy of the deep cerebellar nuclei. Both basal ganglia and cerebellar nuclei show an increasing iron content in healthy human subjects with increasing age. Clusters of iron are paramagnetic and, therefore, tend to cause local inhomogenities in a magnetic field. The iron-induced susceptibility artefacts were used to visualize the cerebellar nuclei as hypointensities on MR images. A three-dimensional axial volume of the cerebellum was acquired using a multigradient echo sequence on a Siemens Sonata 1.5 Tesla MR (FOV = 220 mm, number of partitions = 84, voxel size = 1.15 x 0.86 x 1.00 mm3, TR/TE = 70/50 ms, flip angle =8 degrees). Each volume was r...

While actively-controlled rectus pulleys explain Listing’s Law (L1) during visually-guided eye movements, it has been difficult to account for violations during the VOR. Tri-planar gadodiamide contrast MRI was obtained in 10 adult humans during central target fixation while positioned in the right (RD) and left (LD) lateral decubitus positions to evoke static ocular counter-rolling. EOM cross sections and paths were determined from area centroids. Paths were used to locate pulleys in 3-D. Correct head orientation was verified from MRI images. Significant (P < 0.01) binocular counter-rotational repositioning in the coronal plane averaging 4.1° (max 8.7°) from RD to LD was observed for inferior, medial, and superior rectus pulleys, with a trend for lateral rectus averaging 1.4°. Pulley array incyclorotation was associated with significant contractile thickening of the superior oblique (SO) and thinning of the inferior oblique (IO) muscles, while excyclorotation was associated with SO thinning and IO thickeni...

Mental chess allows investigating the network of brain areas underlying mental imagery in highly trained individuals. Three amateur chess players (ELO rating > 2000) performed imagined chess movements (rule retrieval by examining movement options, initial moves during opening session) using an alternating task design (30 s activation, 30 s baseline). Control conditions included continuous multiplication of single-digit numbers and arbitrary movements on the chessboard. Real-time whole brain fMRI was performed on a 1.5 T MR scanner (TR 3 s, TE 66 ms, voxel size 6x6x6 mm3). Rule retrieval versus number multiplication resulted in strong activations in parietal cortex (precuneus) and weaker activity in temporal cortex, bilateral dorsolateral prefrontal cortex (BA46, BA9), bilateral motor cortex and in visual areas, possibly area V4/V5, consistent with results from PET and SPECT studies (1,2). Opening moves versus arbitrary movements, as well as rule retrieval versus arbitrary movements, resulted in predominant...

In order to determine if gray matter thickening in the left inferior frontal cortex was related specifically to the maturation of language skills rather than representing a general developmental change nonspecific to language, we examined whether thickening of this region was correlated with phonological processing but not with hand skills. Such specificity would illustrate double dissociation of developmental functional anatomy. We studied 45 normally developing children (between ages 5 and 11) over two years. We analyzed structural MRI data using cortical pattern matching methods, and correlated within-individual changes in thickness to two behavioral scores: Phonological processing (PHONO) and motor performance (MOTOR). White areas of the figure represent positive correlation between change in gray matter thickness and behavioral scores. In red are areas of negative Pearson's r. As predicted, improving PHONO score was associated with gray matter thickening in the left inferior frontal cortex. By contras...