Department of Psychiatry

Schizophrenia Research Faculty
Robert Freedman, MD
Laura Martin, MD
Don Rojas, PhD
Jason Tregellas, PhD

Overview
Invesigators at the Brain Imaging Center are interested in several aspects of neuropathology in schizophrenia, including inhibitory dysfuction, the involvement of the cholinergic system, and auditory processing.

Inhibitory Dysfuction and Involvement of Cholinergic Systems

Inhibitory dysfunction is thought to be a core feature of schizophrenia.  Our lab currently is studying frequently observed deficits thought to reflect problems in inhibitory processes at the neuronal level.

I. Sensory Gating Deficits

People with schizophrenia are often unable to ignore or filter out unimportant information in the environment.  This "sensory gating" deficit may be related to disease pathology.  Although this deficit has been well studied over the last two decades using electroencephalography (EEG), we still do not understand which brain regions are involved in this process.  To determine which parts of the brain are involved, we have developed a measure of sensory gating compatible with functional magnetic resonance imaging (fMRI).  Intriguing new results from the first round of this study will be available here in 2007.

II. Smooth pursuit eye movement (SPEM) deficits

SPEM deficits in patients with schizophrenia are one of the most reproducible physiologic abnormalities associated with the disease.  We are using fMRI to understand differences in brain function during pursuit eye movements in patients with schizophrenia.

The image to the right shows brain regions used during a smooth pursuit eye movement task (below) in healthy subjects.

A small white dot travels back and forth across the screen during the eye movement task.

See Publications for recent findings in schizophrenia.

III. Neurobiology of Cholinergic System in Schizophrenia

Much evidence points to the involvment of nicotinic choliergic systems in schizophrenia. Our lab is interested in the biology underlying this process. As such, current projects are examining the effects of nicotine on mismatch negativity indices as well as the effects of nicotine on cortical activation patterns during a smooth pursuit eye movement task in persons with schizophrenia. However, nicotine has several drawbacks, in that it is addictive, tobacco has numerous adverse health effects, and nicotine’s long term efficacy is limited by tachyphylaxis.  Thus, we are also interested in learning more about the potential alpha-7 nicotinic agonists as a therapeutic class in schizophrenia.

Auditory Processing Deficits in Schizophrenia

Deficits in basic auditory perception have been described in schizophrenia. Previous electrophysiologic imaging research has documented a structure-function disassociation in the auditory system in schizophrenia. Current studies are examining whether the most fundamental level of auditory cortical organization, tonotopy, is altered in schizophrenia.

The image to the right shows responses to a 2000 Hz tone using both magnetoencephalography (MEG) and fMRI.