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Poor attention and impaired memory are enduring and core features of schizophrenia. These impairments have been attributed either to global cortical dysfunction or to perturbations of specific components associated with the dorsolateral prefrontal cortex (DLPFC), hippocampus and cerebellum. Here, we used positron emission tomography (PET) to dissociate(More)
OBJECTIVE The thalamus and cerebral cortex are connected via topographically organized, reciprocal connections. Previous studies have revealed thalamic abnormalities in schizophrenia; however, it is not known whether thalamocortical networks are differentially affected in the disorder. To explore this possibility, the authors examined functional(More)
BACKGROUND Patients with schizophrenia demonstrate poor verbal memory, ascribed to impaired prefrontal and hippocampal function. Healthy adults can increase recall accuracy following encoding interventions, such as item repetition and the formation of semantic associations. We examined the effects of these interventions on both memory performance and(More)
Studies in rodents have demonstrated that the integration and flexible expression of memories, necessary for transitive inference, depend on an intact hippocampus. To test this hypothesis in humans, we studied brain activation during the discrimination of a series of overlapping and non-overlapping arbitrary visual stimulus pairs. We report that transitive(More)
The effects on anatomy and behavior of a ribosomal inactivating protein (saporin) coupled to a monoclonal antibody against the low-affinity NGF receptor (NGFr) were examined. In adult rats, NGFr is expressed predominantly in cholinergic neurons of the medial septal area (MSA), diagonal band nuclei, and nucleus basalis magnocellularis (nBM), but also in(More)
Neurobiological theories posit that schizophrenia relates to disturbances in connectivity between brain regions. Resting-state functional magnetic resonance imaging is a powerful tool for examining functional connectivity and has revealed several canonical brain networks, including the default mode, dorsal attention, executive control, and salience(More)
Many risk genes interact synergistically to produce schizophrenia and many neurotransmitter interactions have been implicated. We have developed a circuit-based framework for understanding gene and neurotransmitter interactions. NMDAR hypofunction has been implicated in schizophrenia because NMDAR antagonists reproduce symptoms of the disease. One action of(More)
Amphetamine is a psychostimulant drug of abuse that can produce long-lived changes in behavior including sensitization and dependence. The neural substrates of these drug effects remain unknown, but based on their prolonged time course, we hypothesize that they involve drug-induced alterations in gene expression. It has recently been demonstrated that(More)
Previous research has implicated the striatum in implicit sequence learning. However, imaging findings have been inconsistent with regard to activity within the thalamus during performance of such tasks. Contemporary models of cortico-striato-thalamic circuitry suggest opposing influences on thalamic activity; suppression of thalamic activity is mediated by(More)
Three neuroimaging techniques, morphometric neuroimaging, magnetic resonance spectroscopy, and functional neuroimaging, have provided evidence for abnormal hippocampal structure and function in schizophrenia. Hippocampal volume reduction is now one of the most consistent structural abnormalities found in schizophrenia: it is present at the onset of the(More)