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Biomedical subjects

Monte S Buchsbaum

Publications and source records attributed to Monte S Buchsbaum.

51 records · Page 3Linked to original sources
PubMed2004

Response inhibition in adolescents diagnosed with attention deficit hyperactivity disorder during childhood: an event-related FMRI study.

OBJECTIVE: Frontostriatal neural abnormalities have been implicated in the response inhibition impairments that are characteristic of attention deficit hyperactivity disorder (ADHD). However, reports of such abnormalities in adolescents are inconsistent. The present study used behavioral and functional neuroimaging techniques to examine inhibitory control processes in adolescents who had been diagnosed with ADHD during childhood. METHOD: The authors used functional magnetic resonance imaging (fMRI) during performance of a Go/No-Go task to scan 10 male adolescents who were diagnosed with DSM-III-R ADHD when they were 7 to 11 years old and nine age-, sex-, and IQ-matched comparison subjects with no history of ADHD. Response inhibition was tested by contrasting neural activation during No-Go trials with that during Go trials. RESULTS: The inhibition of a prepotent tendency to respond produced markedly greater activation of the left anterior cingulate gyrus, bilateral frontopolar regions, bilateral ventrolateral prefrontal cortex, and left medial frontal gyrus in the adolescents with childhood ADHD than in the adolescents with no history of ADHD. Activity in the first two regions was inversely related to task performance across the study group. CONCLUSIONS: Compared with adolescents who had no history of ADHD, adolescents who were diagnosed with ADHD during childhood exhibited enhanced responses during inhibition in ventrolateral prefrontal cortical areas that subserve response inhibition, as well as in anterior cingulate and frontopolar regions implicated in other executive functions.

Adolescent↗
PubMed2003

Caudate and putamen volumes in good and poor outcome patients with schizophrenia.

Magnetic resonance images of 37 patients with schizophrenia and 37 age- and sex-matched volunteers were acquired. The caudate nucleus and putamen were traced on axial slices from the most superior extent of the caudate to the most inferior point where the caudate and putamen merge. Two subtypes of schizophrenia were compared, the Kraepelinian subtype (n=13), characterized by an unremitting and severe course, and the non-Kraepelinian subtype (n=24), characterized by a remitting course and some periods of self-care. Patients with good outcome schizophrenia had larger relative mean putamen size (0.0129) than poor outcome patients (0.0123) or normal controls (0.0121), but not caudate size. This enlargement was most marked for the dorsal putamen and right hemisphere. Striatal size was not related to whether patients were currently being treated with atypical or typical neuroleptics or whether they had been predominantly treated with typical or atypical neuroleptics over the past 3 years. This suggests the possibility that the expansion of putamen size may be a physiological correlate of neuroleptic responsiveness or that small putamen size at disease onset may be a predictor of outcome.

Adult↗
PubMed2003

Magnetic resonance imaging of mediodorsal, pulvinar, and centromedian nuclei of the thalamus in patients with schizophrenia.

BACKGROUND: Postmortem and magnetic resonance imaging (MRI) data have suggested volume reductions in the mediodorsal (MDN) and pulvinar nuclei (PUL) of the thalamus. The centromedian nucleus (CMN), important in attention and arousal, has not been previously studied with MRI. METHODS: A sample of 41 patients with schizophrenia (32 men and 9 women) and 60 healthy volunteers (45 men and 15 women) underwent assessment with high-resolution 1.2-mm thick anatomical MRI. Images were differentiated to enhance the edges and outline of the whole thalamus, and the MDN, PUL, and CMN were outlined on all slices by a tracer masked to diagnostic status. RESULTS: Significantly smaller volumes of the MDN and PUL were found in patients with schizophrenia compared with controls. Volume relative to brain size was reduced in all 3 nuclei; differences in relative reduction did not differ among the nuclei. The remainder of the thalamic volume (whole thalamus minus the volume of the 3 delineated nuclei) was not different between schizophrenic patients and controls, indicating that the volume reduction was specific to these nuclei. Volume relative to brain size was reduced in all 3 nuclei and remained significant when only patients who had never been exposed to neuroleptic medication (n = 15) were considered. For the MDN, women had larger relative volumes than men among controls, but men had larger volumes than women among schizophrenic patients. CONCLUSIONS: Three association regions of the thalamus that have reciprocal connectivity to schizophrenia-associated regions of the cortex have significantly smaller volumes on MRI in patients with schizophrenia.

Adolescent↗
PubMed2003

Selective attention, inhibition for repeated events and hemispheric specialization.

When two visual events appear consecutively in the same spatial location, our response to the second event is slower than to the first. This inhibition for repeated events may reflect a bias toward sampling novel locations, a bias useful for exploring visual space. It has been shown that the left hemisphere is more specialized in selective attentional processes than the right one. The aim of the present experiment was to test if this hemispheric specialization for selective attention may also affect the inhibition for repeated events. For this purpose, we asked 11 normal subjects to perform an identity-based discrimination task in which the target to be detected could appear alone or surrounded by flanking letters, in the left or in the right visual field. Results show that inhibition for repeated events is present only when selective attention is required and when the task is performed in the right specialized visual field.

Adult↗
PubMed2003

Striatal size, glucose metabolic rate, and verbal learning in normal aging.

The striatum has recently been implicated as an area that may mediate age-associated cognitive decline because of diminution of volume and functional activity. We used 18F-fluorodeoxyglucose (FDG) with positron emission tomography (PET) and high-resolution magnetic resonance imaging (MRI) to examine the effects of age on striatal glucose metabolic rate and size in 70 healthy, normal subjects. During the FDG tracer uptake period, subjects performed a serial verbal learning task, based on the California Verbal Learning Test. PET images were co-registered to the MR images. The interrelations among striatal glucose metabolic rate, size, and performance on the verbal learning task were examined with repeated-measures analysis of variance and correlational analysis. As age increased, relative glucose metabolic rate (GMR) increased in the putamen and decreased in the caudate. Female subjects had lower relative GMR than male subjects in the caudate, but equal in the putamen. Striatal size remained relatively constant across the lifespan in men but was lower in women aged 50-70 than in men. While there were significant associations between striatal activity and performance on the uptake task, these findings were mostly accounted for by age. The findings are consistent with our earlier report on the same cohort that demonstrated an age-related shift from anterior to posterior cortical metabolism, as the putamen receives primarily posterior cortical input and the caudate receives relatively more anterior cortical input. Findings of significant involvement of striatal functioning in verbal learning are most likely accounted for by age and suggest an age-related shift from anterior to posterior circuitry in the human telencephalon.

Adult↗
PubMed2003

MRI assessment of gray and white matter distribution in Brodmann's areas of the cortex in patients with schizophrenia with good and poor outcomes.

OBJECTIVE: High-resolution magnetic resonance imaging (MRI) was used to compare cortical gray and white matter and CSF volumes in schizophrenia patients with poor outcomes, schizophrenia patients with good outcomes, and healthy comparison subjects. METHOD: T(1)-weighted, 1.2-mm-thick MR images were acquired for 37 patients with schizophrenia and 37 healthy, age- and sex-matched comparison subjects. The patients were assigned to subgroups with poor outcomes (N=13) and good outcomes (N=24) on the basis of clinical characteristics. Poor-outcome patients were those who were continuously hospitalized or completely dependent on others for basic needs, were unemployed, and had severe negative symptoms and severe formal thought disorder. The MR images were reoriented to standard position parallel to the anterior commissure-posterior commissure line and segmented into CSF, gray matter, and white matter tissue types. The tissue types were assigned to Brodmann's areas by using the Perry postmortem histological atlas, and tissue-type volumes in the three subject groups were compared. RESULTS: Compared to the healthy subjects, the overall patient group had a significantly smaller mean cortical gray matter volume and significantly larger mean CSF volume, especially in the frontal lobe and left temporal lobe. The smaller frontal lobe volume in schizophrenia was confirmed for unadjusted volumes and for volumes with adjustment for whole brain volumes. Compared to patients with good outcomes, patients with poor outcomes (Kraepelinian schizophrenia) had significantly smaller gray matter volumes in the temporal and occipital lobes, but no difference between groups was found for total frontal lobe volume. Only 21% of the healthy subjects had volumes 0.5 standard deviations below the mean for healthy subjects in any area of the frontal or temporal lobes, compared with 62% of poor-outcome patients. CONCLUSIONS: Poor outcome in patients with schizophrenia may be associated with a more posterior distribution (posteriorization) of gray matter deficits across widely distributed cortical regions.

Activities of Daily Living↗
PubMed2003

Deficient attentional modulation of the startle response in patients with schizotypal personality disorder.

OBJECTIVE: Attentional deficits have been identified as an abnormality that individuals with schizotypal personality disorder share with schizophrenia patients. The purpose of this study was to examine automatic sensorimotor gating and controlled attentional modulation of the startle eye blink response in unmedicated subjects with schizotypal personality disorder. METHOD: Eighteen unmedicated patients with schizotypal personality disorder and 16 healthy individuals were assessed in an acoustic attention-to-prepulse paradigm. The participants performed a selective attention task involving the presentation of attended, ignored, and novel tones that served as prepulse tones. Acoustic startle probes were presented at short and long lead intervals after the onset of tones and occasionally during the intertone interval. RESULTS: The comparison subjects showed greater prepulse inhibition and prepulse facilitation during the attended than the ignored prepulses, demonstrating early and later attentional modulation of startle eye blink response. In contrast, the subjects with schizotypal personality disorder failed to show this pattern. CONCLUSIONS: Subjects with schizotypal personality disorder have deficits in controlled attentional processing, as indexed by modification of the startle eye blink response, that are similar to those observed in patients with schizophrenia.

Acoustic Stimulation↗
PubMed2002

Kraepelinian and non-Kraepelinian schizophrenia subgroup differences in cerebral metabolic rate.

We studied two subtypes of schizophrenia. the Kraepelinian subtype (n = 10) characterized by an unremitting and severe course and the non-Kraepelinian subtype (n = 17) characterized by a remitting course and some periods of self-care. Patients were assessed with positron emission tomography (PET) with 18F-deoxyglucose (FDG) and high-resolution magnetic resonance imaging (MRI). A group of 32 age- and sex-matched normal volunteers served as comparison subjects. During the FDG tracer uptake period, patients performed a serial verbal learning task. MR images were segmented into gray, white and cerebrospinal fluid regions, and warped to average normal coordinates. PET images were coregistered to the MR images and similarly warpedfor analysis. Kraepelinian subtype patients were characterized by lower metabolic rates in the temporal lobe and cingulategyrus. and lower fronto/occipital ratios than non-Kraepelinian subtype patients. Exploratory statistical probability mapping alsorevealed lower metabolic rates in the right striatum in Kraepelinian versus non-Kraepelinian patients. These differences couldnot be attributed to differences in age, symptom severity, task performance during FDG uptake, or severity of involuntary movements. Factor analysis of the cortical surface identified significantly lower temporal lobe metabolic rates in Kraepelinian patients than non-Kraepelinian patients. A combined frontal/temporal deficit or greater cortical change may be associated with poorer longitudinal course.

Activities of Daily Living↗
PubMed2002

Differential metabolic rates in prefrontal and temporal Brodmann areas in schizophrenia and schizotypal personality disorder.

In an exploration of the schizophrenia spectrum, we compared cortical metabolic rates in unmedicated patients with schizophrenia and schizotypal personality disorder (SPD) with findings in age- and sex-matched normal volunteers. Coregistered magnetic resonance imaging (MRI) and positron emission tomography (PET) scans were obtained in 27 schizophrenic, 13 SPD, and 32 normal volunteers who performed a serial verbal learning test during tracer uptake. A template of Brodmann areas derived from a whole brain histological section atlas was used to analyze PET findings. Significantly lower metabolic rates were found in prefrontal areas 44-46 in schizophrenic patients than in normal volunteers. SPD patients did not differ from normal volunteers in most lateral frontal regions, but they had values intermediate between those of normal volunteers and schizophrenic patients in lateral temporal regions. SPD patients showed higher than normal metabolic rates in both medial frontal and medial temporal areas. Metabolic rates in Brodmann area 10 were distinctly higher in SPD patients than in either normal volunteers or schizophrenic patients.

Adult↗
PubMed2002

Blunted prefrontal cortical 18fluorodeoxyglucose positron emission tomography response to meta-chlorophenylpiperazine in impulsive aggression.

BACKGROUND: Impulsive aggression is a prevalent problem and yet little is known about its neurobiology. Preclinical and human studies suggest that the orbital frontal cortex and anterior cingulate cortex play an inhibitory role in the regulation of aggression. METHODS: Using positron emission tomography, regional metabolic activity in response to a serotonergic stimulus, meta-chlorophenylpiperazine (m-CPP), was examined in 13 subjects with impulsive aggression and 13 normal controls. The anterior cingulate and medial orbitofrontal regions were hypothesized to respond differentially to m-CPP in patients and controls. In the frontal cortex, regional metabolic glucose response to m-CPP was entered into a group (impulsive aggressive, control) x slice (dorsal, middle, orbital) x position (medial, lateral) x location (anterior, posterior) x hemisphere (right, left) mixed-factorial analysis of variance design. A separate group (impulsive aggressive, controls) x anteroposterior location (Brodmann areas 25, 24, 31, 29) x hemisphere (right, left) analysis of variance was used to examine regional glucose metabolism in the cingulate gyrus. RESULTS: Unlike normal subjects, patients with impulsive aggression did not show activation specifically in the left anteromedial orbital cortex in response to m-CPP. The anterior cingulate, normally activated by m-CPP, was deactivated in patients; in contrast, the posterior cingulate gyrus was activated in patients and deactivated in controls. CONCLUSIONS: The decreased activation of inhibitory regions in patients with impulsive aggression in response to a serotonergic stimulus may contribute to their difficulty in modulating aggressive impulses.

Aggression↗
PubMed2002

Neuroimaging studies in post-traumatic stress disorder.

The authors review some of the advances that have been made in understanding the structural, biochemical, and functional neuroanatomy of post-traumatic stress disorder (PTSD). First, the authors review the primary brain regions that had been hypothesized a priori, from the phenomenology and neurobiology of PTSD, to be implicated in the pathophysiology. Next, they review findings from neuroimaging studies of these brain regions in PTSD, and explain the various experimental methods and imaging technologies used in these studies. A broader perspective, including a discussion of additional brain areas that may be involved in PTSD, is synthesized. The authors conclude with a rationale and approach for studies testing sharply defined hypotheses and those using multidisciplinary strategies that integrate neuroimaging data with other cognitive, biologic, and genetic tools to study this complex disorder.

Amygdala↗
PubMed2002

Postmortem assessment of thalamic nuclear volumes in subjects with schizophrenia.

OBJECTIVE: The authors assessed schizophrenia-associated changes in volume and neuronal number in the mediodorsal nucleus and the pulvinar regions of the thalamus. METHOD: Right-hemisphere thalami obtained at autopsy from 14 schizophrenic and eight comparison subjects were examined. Computer-assisted morphometric techniques were used to determine volumes for the mediodorsal nucleus, pulvinar, and the anterior and centromedian nuclei as well as the parvocellular, magnocellular, and caudodorsal subdivisions of the mediodorsal nucleus. Neurons in the mediodorsal nucleus and pulvinar were counted and measured by using a stereology-based sampling strategy. RESULTS: Four schizophrenic and three comparison subjects had Alzheimer's type pathology, leaving 10 schizophrenic and five comparison subjects without other documented neuropathological changes. In analyses that included either the full cohort or only the subjects without Alzheimer's type pathology, volumes of the mediodorsal nucleus and pulvinar, but not the anterior or centromedian nuclei, were significantly smaller in the schizophrenic subjects. For the schizophrenic subjects, neuronal number in the mediodorsal nucleus, parvocellular subdivision, and pulvinar was significantly lower, and neuronal size in the mediodorsal nucleus, caudodorsal subdivision, and pulvinar was significantly smaller. CONCLUSIONS: Schizophrenia is associated with volume and neuronal changes in the mediodorsal nucleus and pulvinar, the major association nuclei of the thalamus, whereas total thalamic volume and the volumes of anterior and centromedian nuclei were not significantly altered.

Aged↗
PubMed1981

Opiate pharmacology and individual differences. I. Psychophysical pain measurements.

A new electric stimulation pain assessment technique using the Tursky electrode and a non-parametric analysis of subjects ratings was found sensitive to aspirin, morphine and opiate antagonists in a series of double-blind cross-over trials in normal adults. Stable individual differences in pain sensitivity (off medication) were maintained on two testing sessions 7 months apart. Older individuals were less pain sensitive than younger individuals. Men were more insensitive than women under age 30. Together, these results suggest the empiric usefulness of this pain measurement technique.

Adolescent↗
PubMed1981

Opiate pharmacology and individual differences. II. Somatosensory evoked potentials.

Somatosensory evoked potentials (EPs) to stimuli ranging from barely perceptible to painful were recorded in 153 normal adults. Reliability of amplitude and amplitude/intensity slopes were demonstrated in 29 individuals tested twice, two or more weeks apart. In randomized, double-blind placebo controlled trials, both aspirin and morphine significantly diminished N120 component at high stimulus intensities. Age, sex and pharmacological effects paralleled those found with psychophysical techniques in part I of this study.

Adolescent↗