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NEUROIMAGING CENTER

Cognitive Neuroimaging and Neuropsychology Laboratory

Research Initiative

The Cognitive Neuroimaging Laboratory is dedicated to the examination of cognitive and affective correlates of neural systems, which may mediate symptoms in psychiatric disorders. Techniques used in these investigations include studies of neuropsychological performance, neurological hard signs, and magnetic resonance imaging methods. The aim of these studies has been to identify brain abnormalities, particularly disruptions of the frontally mediated networks, which may represent risk factors for psychiatric illness or may be the site of pathology in these illnesses. Recent investigations have combined results from neuropsychological testing and brain imaging in healthy subjects and subjects with psychiatric disorders as a means of clarifying the possible dysfunctional neural network processes associated with these illnesses.

Research Highlights

To investigate hypotheses derived from neuropsychological studies of adult psychiatric patients, investigators in the Cognitive Neuroimaging Laboratory have successfully applied techniques in brain imaging, including structural morphometry, functional magnetic resonance imaging, and proton magnetic resonance spectroscopy to the study of schizophrenia and bipolar disorder. Most recently, the Cognitive Neuroimaging Laboratory has examined the potential etiologic bases of neural models of dysfunction in psychotic disorders by applying functional magnetic resonance techniques to examine cortical changes during development.

In a recent series of fMRI studies, patients with bipolar disorder and healthy control subjects were examined while performing a cognitive task of inhibition. Results indicate that relative to controls, bipolar patients demonstrated significantly reduced signal intensity within an area of the anterior cingulate which accompanied an increase in the prefrontal cortex during the task, suggesting differential processing strategies of bipolar patients and supporting the theory of altered frontal systems in these patients.

FMRI studies of stable schizophrenic patients during a sequential finger tapping task have demonstrated a significant reduction in contralateral and ipsilateral brain activity in both the primary motor cortex, (BA4) and the premotor and supplementary motor are (BA6) relative to control subjects. These findings suggest that motor system abnormalities are indeed present and identifiable on the basis of BOLD imaging in schizophrenic patients.

In an fMRI study designed to examine patterns of cortical activation underlying D-cycloserine’s therapeutic efficacy in schizophrenic patients, frontal and temporal lobe activity was measured during the performance of a verbal fluency test at baseline and after 8 weeks of supervised treatment. Patients who received D-cycloserine added to their dose of conventional neuroleptic demonstrated an increase in temporal lobe activity at the 8 week timepoint, which accompanied a decrease in negative symptoms relative to the patients who received placebo added to their dose of neuroleptic. These results suggest that the addition of D-cycloserine to conventional neuroleptics may improve negative symptoms through enhanced temporal lobe function.

BOLD fMRI data revealed that marijuana smokers, tested within 4 to 36 hours of discontinuation, exhibited significantly less activation than controls in the anterior cingulate bilaterally during right- and left-sided finger sequencing as compared to control subjects. These results suggest that recently abstinent chronic cannabis smokers produce reduced activation in motor cortical areas in response to finger sequencing compared to controls.

In a second important finding from this investigation, fMR imaging of recent heavy cannabis smokers during the performance of a working memory task who were tested within 6-36 hours of abstinence revealed increased activation of brain regions typically used for spatial working memory tasks, inlcluding the prefrontal cortex and anterior cingulate relative to control subjects. These findings suggest altered processing during the performance of working memory tasks in cannabis smoking subjects during early abstinence.

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