Magnetic Resonance Imaging (MRI)

PR04.MZ was designed as a highly selective dopamine transporter inhibitor, derived from natural cocaine. Its binding profile indicates that [(11)C]PR04.MZ may be suited as a PET radioligand for the non-invasive exploration of striatal and extrastriatal DAT populations. As a key feature, its structural design facilitates both, labelling with fluorine-18 at its terminally fluorinated butynyl moiety and carbon-11 at its methyl ester function.

BACKGROUND: Cigarette smoking and nicotine have complex effects on human physiology and behavior, including some effects similar to those elicited by inhibition of aromatase, the last enzyme in estrogen biosynthesis. We report the first in vivo primate study to determine whether there is a direct effect of nicotine administration on brain aromatase.
METHODS: Brain aromatase availability was examined with positron emission tomography and the selective aromatase inhibitor [(11)C]vorozole in six baboons before and after exposure to IV nicotine at .015 and .03 mg/kg.

BACKGROUND: Deficits in the capacity to reflect about the self and others ("social reflection" [SR]) have been identified in schizophrenia, as well as in people with a genetic or clinical risk for the disorder. However, the neural underpinnings of these abnormalities are incompletely understood.

Patients with schizophrenia may have altered pain perception, as suggested by clinical reports of pain insensitivity, and recent neuroimaging findings. Here, we examined neural responses to an aversive electrical stimulus and the immediate anticipation of such a stimulus using fMRI and a classical conditioning paradigm, which involved pairing an electrical shock with a neutral photograph. Fifteen men with schizophrenia and 13 healthy men, matched for demographic characteristics, electrical stimulation level and scan movement, were studied.

BACKGROUND: In healthy individuals, the activity of the medial temporal lobe habituates rapidly with the repeated presentation of a stimulus. Using functional magnetic resonance imaging (fMRI), we tested the hypothesis that habituation of the medial temporal lobe is reduced in schizophrenia.

CONTEXT Abnormalities in associative memory processes, such as Pavlovian fear conditioning and extinction, have been observed in schizophrenia. The retrieval of fear extinction memories (safety signals) may be particularly affected; although schizophrenic patients can extinguish conditioned fear, they show a deficit in retrieving fear extinction memories after a delay.

The brain is a vastly interconnected organ and methods are needed to investigate its long range structure(S)-function(F) associations to better understand disorders such as schizophrenia that are hypothesized to be due to distributed disconnected brain regions. In previous work we introduced a methodology to reduce the whole brain S-F correlations to a histogram and here we reduce the correlations to brain clusters.

INTRODUCTION: Patients with schizophrenia show deficits in facial affect and facial identity recognition and exhibit structural and neurophysiological abnormalities in brain regions known to mediate these processes. Functional neuroimaging studies of neural responses to emotional facial expressions in schizophrenia have reported both increases and decreases in medial temporal lobe (MTL) activity in schizophrenia. Some of this variability may be related to the tasks performed and the baseline conditions used.

A parietal-frontal network in primates is thought to support many behaviors occurring in the space around the body, including interpersonal interactions and maintenance of a particular "comfort zone" or distance from other people ("personal space"). To better understand this network in humans, we used functional MRI to measure the responses to moving objects (faces, cars, simple spheres) and the functional connectivity of two regions in this network, the dorsal intraparietal sulcus (DIPS) and the ventral premotor cortex (PMv).

BACKGROUND: Deficits in social cognition, including impairments in self-awareness, contribute to the overall functional disability associated with schizophrenia. Studies in healthy subjects have shown that social cognitive functions, including self-reflection, rely on the medial prefrontal cortex (mPFC) and posterior cingulate gyrus, and these regions exhibit highly correlated activity during "resting" states.