Faculty Bibliography

BACKGROUND: The disconnection hypothesis of schizophrenia has been extensively tested in adults. Recent studies have reported the presence of brain disconnection in younger patients, adding evidence to support the neurodevelopmental hypothesis of schizophrenia. Because of drug confounds in chronic and medicated patients, it has been extremely challenging for researchers to directly investigate abnormalities in the development of connectivity and their role in the pathophysiology of schizophrenia. The present study aimed to examine functional homotopy - a measure of interhemispheric connection - and its relevance to clinical symptoms in first-episode drug-naive early-onset schizophrenia (EOS) patients. METHODS: Resting-state functional magnetic resonance imaging was performed in 26 first-episode drug-naive EOS patients (age: 14.5 +/- 1.94, 13 males) and 25 matched typically developing controls (TDCs) (age: 14.4 +/- 2.97, 13 males). We were mainly concerned with the functional connectivity between any pair of symmetric interhemispheric voxels (i.e., functional homotopy) measured by voxel-mirrored homotopic connectivity (VMHC). RESULTS: Early-onset schizophrenia patients exhibited both global and regional VMHC reductions in comparison with TDCs. Reduced VMHC values were observed within the superior temporal cortex and postcentral gyrus. These interhemispheric synchronization deficits were negatively correlated with negative symptom of the Positive and Negative Syndrome Scale. Moreover, regions of interest analyses based on left and right clusters of temporal cortex and postcentral gyrus revealed abnormal heterotopic connectivity in EOS patients. CONCLUSIONS: Our findings provide novel neurodevelopmental evidence for the disconnection hypothesis of schizophrenia and suggest that these alterations occur early in the course of the disease and are independent of medication status.

BACKGROUND:Intact sarcasm perception is a crucial component of social cognition and mentalizing (the ability to understand the mental state of oneself and others). In sarcasm, tone of voice is used to negate the literal meaning of an utterance. In particular, changes in pitch are used to distinguish between sincere and sarcastic utterances. Schizophrenia patients show well-replicated deficits in auditory function and functional connectivity (FC) within and between auditory cortical regions. In this study we investigated the contributions of auditory deficits to sarcasm perception in schizophrenia. METHOD/METHODS:Auditory measures including pitch processing, auditory emotion recognition (AER) and sarcasm detection were obtained from 76 patients with schizophrenia/schizo-affective disorder and 72 controls. Resting-state FC (rsFC) was obtained from a subsample and was analyzed using seeds placed in both auditory cortex and meta-analysis-defined core-mentalizing regions relative to auditory performance. RESULTS:Patients showed large effect-size deficits across auditory measures. Sarcasm deficits correlated significantly with general functioning and impaired pitch processing both across groups and within the patient group alone. Patients also showed reduced sensitivity to alterations in mean pitch and variability. For patients, sarcasm discrimination correlated exclusively with the level of rsFC within primary auditory regions whereas for controls, correlations were observed exclusively within core-mentalizing regions (the right posterior superior temporal gyrus, anterior superior temporal sulcus and insula, and left posterior medial temporal gyrus). CONCLUSIONS:These findings confirm the contribution of auditory deficits to theory of mind (ToM) impairments in schizophrenia, and demonstrate that FC within auditory, but not core-mentalizing, regions is rate limiting with respect to sarcasm detection in schizophrenia.

Objective: Aggression in schizophrenia is a major societal issue, leading to physical harm, stigmatization, patient distress, and higher health care costs. Impulsivity is associated with aggression in schizophrenia, but it is multidetermined. The subconstruct of urgency is likely to play an important role in this aggression, with positive urgency referring to rash action in the context of positive emotion, and negative urgency referring to rash action in the context of negative emotion. Method: The authors examined urgency and its neural correlates in 33 patients with schizophrenia or schizoaffective disorder and 31 healthy comparison subjects. Urgency was measured using the Urgency, Premeditation, Perseverance, and Sensation-Seeking scale. Aggressive attitudes were measured using the Buss-Perry Aggression Questionnaire. Results: Positive urgency, negative urgency, and aggressive attitudes were significantly and selectively elevated in schizophrenia patients (Cohen's d values, 1.21-1.50). Positive and negative urgency significantly correlated with the Aggression Questionnaire total score (r>0.48 in all cases) and each uniquely accounted for a significant portion of the variance in aggression over and above the effect of group. Urgency scores correlated with reduced cortical thickness in ventral prefrontal regions including the right frontal pole, the medial and lateral orbitofrontal gyrus and inferior frontal gyri, and the rostral anterior cingulate cortex. In patients, reduced resting-state functional connectivity in some of these regions was associated with higher urgency. Conclusions: These findings highlight the key role of urgency in aggressive attitudes in people with schizophrenia and suggest neural substrates of these behaviors. The results also suggest behavioral and neural targets for interventions to remediate urgency and aggression.

BACKGROUND: Apathy is a prominent feature of geriatric depression that predicts poor clinical outcomes and hinders depression treatment. Yet little is known about the neurobiology and treatment of apathy in late-life depression. This study examined apathy prevalence in a clinical sample of depressed elderly, response of apathy to selective serotonin reuptake inhibitor (SSRI) treatment, and neuroanatomical correlates that distinguished responders from non-responders and healthy controls. METHODS: Participants included 45 non-demented, elderly with major depression and 43 elderly comparison individuals. After a 2-week single-blind placebo period, depressed participants received escitalopram 10mg daily for 12 weeks. The Apathy Evaluation Scale (AES) and 24-item Hamilton Depression Rating Scale (HDRS) were administered at baseline and 12 weeks. MRI scans were acquired at baseline for concurrent structural and diffusion tensor imaging of anterior cingulate gray matter and associated white matter tracts. RESULTS: 35.5% of depressed patients suffered from apathy. This declined to 15.6% (p<0.1) following treatment, but 43% of initial sufferers continued to report significant apathy. Improvement of apathy with SSRI was independent of change in depression but correlated with larger left posterior subgenual cingulate volumes and greater fractional anisotropy of left uncinate fasciculi. LIMITATIONS: Modest sample size, no placebo control, post-hoc secondary analysis, use of 1.5T MRI scanner CONCLUSIONS: While prevalent in geriatric depression, apathy is separable from depression with regards to medication response. Structural abnormalities of the posterior subgenual cingulate and uncinate fasciculus may perpetuate apathetic states by interfering with prefrontal cortical recruitment of limbic activity essential to motivated behavior.

OBJECTIVE: Apathy is prevalent in late-life depression and predicts poor response to antidepressants, chronicity of depression, disability, and greater burden to caregivers. However, little is known about its neurobiology. Salience processing provides motivational context to stimuli. The aim of this study was to examine the salience network (SN) resting-state functional connectivity (rsFC) pattern in elderly depressed subjects with and without apathy. METHODS: Resting-state functional MRI data were collected from 16 non-demented, non-MCI, elderly depressed subjects and 10 normal elderly subjects who were psychotropic-free for at least 2 weeks. The depressed group included 7 elderly, depressed subjects with high comorbid apathy and 9 with low apathy. We analyzed the rsFC patterns of the right anterior insular cortex (rAI), a primary node of the SN. RESULTS: Relative to non-apathetic depressed elderly, depressed elderly subjects with high apathy had decreased rsFC of the rAI to dorsal anterior cingulate and to subcortical/limbic components of the SN. Depressed elderly subjects with high apathy also exhibited increased rsFC of the rAI to right dorsolateral prefrontal cortex and right posterior cingulate cortex when compared to non-apathetic depressed elderly. CONCLUSIONS: Elderly depressed subjects with high apathy display decreased intrinsic rsFC of the SN and an altered pattern of SN rsFC to the right DLPFC node of the central executive network when compared to elderly non-apathetic depressed and normal, elderly subjects. These results suggest a unique biological signature of the apathy of late-life depression and may implicate a role for the rAI and SN in motivated behavior

Patients with schizophrenia exhibit cognitive and sensory impairment, and object recognition deficits have been linked to sensory deficits. The "frame and fill" model of object recognition posits that low spatial frequency (LSF) information rapidly reaches the prefrontal cortex (PFC) and creates a general shape of an object that feeds back to the ventral temporal cortex to assist object recognition. Visual dysfunction findings in schizophrenia suggest a preferential loss of LSF information. This study used functional magnetic resonance imaging (fMRI) and resting state functional connectivity (RSFC) to investigate the contribution of visual deficits to impaired object "framing" circuitry in schizophrenia. Participants were shown object stimuli that were intact or contained only LSF or high spatial frequency (HSF) information. For controls, fMRI revealed preferential activation to LSF information in precuneus, superior temporal, and medial and dorsolateral PFC areas, whereas patients showed a preference for HSF information or no preference. RSFC revealed a lack of connectivity between early visual areas and PFC for patients. These results demonstrate impaired processing of LSF information during object recognition in schizophrenia, with patients instead displaying increased processing of HSF information. This is consistent with findings of a preference for local over global visual information in schizophrenia.

BACKGROUND: Apathy is common in late-life depression and is associated with disability and poor antidepressant response. This study examined whether resting functional connectivity (FC) of the nucleus accumbens (NAcc) and the dorsal anterior cingulate (dACC) with other structures can distinguish apathetic depressed older patients from non-apathetic depressed patients and normal subjects. METHODS: Twenty-six non-demented, non-MCI older adults were studied. Of these, 16 had major depression (7 also had apathy) and 10 had no psychopathology. Resting state fMRI was performed prior to treatment in subjects who were psychotropic-free for at least two weeks. FC was determined by placing seeds in the NAcc and the dACC bilaterally. RESULTS: Apathetic depressed patients had lower FC of the NAcc with the amygdala, caudate, putamen, globus pallidus, and thalamus and increased FC with the dorsomedial prefrontal cortex, the superior frontal cortex, and the insula than non-apathetic patients. Further, apathetic patients had lower FC of the dACC with dorsolateral and ventrolateral prefrontal cortices and higher FC with the insula and the orbitofrontal cortex than non-apathetic patients. LIMITATIONS: Small number of subjects, lack of random sampling, use of a 1.5T MRI scanner. CONCLUSIONS: This preliminary study suggests that FC between the NAcc and the dACC and structures related to reward and related behavioral responses constitute the functional topography of abnormalities characterizing apathy of late life depression. However, replication is needed.

Although many resting state fMRI human studies have been published, the number of such rodent studies is considerably less. The reason for this is the severe technical challenge of high magnetic field small rodent imaging. Local magnetic field susceptibility changes at air tissue boundaries cause image distortion and signal losses. The current study reports measures of functional connectivity in mice using only isoflurane for the anesthetic. Because all anesthetic agents will alter cerebral blood flow and cerebral metabolism, the impact these changes have on neuronal connectivity has yet to be fully understood, however this work reports for the first time that reliable functional connectivity measures in mouse brain can be obtained with isoflurane.

Perception has been identified by the NIMH-sponsored Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) group as a useful domain for assessing cognitive deficits in patients with schizophrenia. Specific measures of contrast gain derived from recordings of steady-state visual evoked potentials (ssVEP) have demonstrated neural deficits within the visual pathways of patients with schizophrenia. Psychophysical measures of contrast sensitivity have also shown functional loss in these patients. In the current study, functional magnetic resonance imaging (fMRI) was used in conjunction with ssVEP and contrast sensitivity testing to elucidate the neural underpinnings of these deficits. During fMRI scanning, participants viewed 1) the same low and higher spatial frequency stimuli used in the psychophysical contrast sensitivity task, at both individual detection threshold contrast and at a high contrast; and 2) the same stimuli used in the ssVEP paradigm, which were designed to be biased toward either the magnocellular or parvocellular visual pathway. Patients showed significant impairment in contrast sensitivity at both spatial frequencies in the psychophysical task, but showed reduced occipital activation volume for low, but not higher, spatial frequency at the low and high contrasts tested in the magnet. As expected, patients exhibited selective deficits under the magnocellular-biased ssVEP condition. However, occipital lobe fMRI responses demonstrated the same general pattern for magnocellular- and parvocellular-biased stimuli across groups. These results indicate dissociation between the fMRI measures and the psychophysical/ssVEP measures. These latter measures appear to have greater value for the functional assessment of the contrast deficits explored here.