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Biomedical subjects

I Liberzon

Publications and source records attributed to I Liberzon.

30 records · Page 2Linked to original sources
PubMed1997

Motivational properties of oxytocin in the conditioned place preference paradigm.

We hypothesized that oxytocin might have intrinsic reinforcing properties and studied it using a conditioned place preference. Three studies examining motivational properties of oxytocin in nonpreferred, preferred, and balance designs were performed utilizing two compartment apparatus. On alternate days, compartments were paired with subcutaneously injected oxytocin (6 mg/kg) or saline, and animal pre- and post-conditioning place preference was compared. Whereas in animals paired with saline there was a shift to a lack of preference, oxytocin-treated animals reversed their preference, spending more time in a previously unpreferred, compartment. In preferred compartment design, oxytocin-treated animals further increased their preference, whereas saline-treated animals decreased their preference toward a nonpreference for either compartment. Our results demonstrate that oxytocin produces a reliable and robust preference for the environment with which it is repeatedly associated, and has rewarding or potentially anti-aversive properties. Future studies are needed to distinguish among these possibilities.

Animals↗
PubMed1996

Longitudinal patterns of care for patients with posttraumatic stress disorder.

This study assessed patterns of mental health service use over time by patients with posttraumatic stress disorder (PTSD) - as compared with patients with schizophrenia and major depression - with emphasis on the persistence and episodic versus continuous nature of use. Data on utilization were extracted from Veterans Health Administration (VA) administrative data bases. Temporal patterns of use were categorized into intervals of inpatient, outpatient, and no use. PTSD patients used substantial amounts of mental health services, but averaged 2.2 nonuse intervals lasting more than 100 days each, implying that use was episodic. Use of mental health services by patients with PTSD is substantial, persistent, and quite episodic. To the extent that use of services reflects the course of the disorder, the results suggest that remissions are usually followed by relapse, and that absence of symptoms does not mean that the disorder has run its course.

Analysis of Variance↗
PubMed1994

Glucocorticoid regulation of hippocampal oxytocin receptor binding.

The effects of glucocorticoid hormones on oxytocin receptors in rat hippocampus were investigated. Oxytocin receptor autoradiography (using 0.1 and 1.2 nM concentrations of [125I]OVTA) revealed a significant (P < 0.02) decrease in oxytocin receptor binding in adrenalectomized animals 7 days after the surgery. Corticosterone replacement at the time of adrenalectomy prevented the decrease in oxytocin binding. The findings were significant in hippocampus and subiculum. These findings suggest regulation of oxytocin receptors, and possibly oxytocin-regulated behaviors by glucocorticoids.

Adrenalectomy↗
PubMed1992

Measurement of depression and negative symptoms in schizophrenia.

The validity of the Hamilton Depression Scale (HAM-D) as a measure of depressive symptomatology in schizophrenic patients is questionable since it was not developed for this purpose, nor has it been validated in a schizophrenic population. Accordingly, 80 schizophrenic inpatients were administered the HAM-D, the 18-item Brief Psychiatric Rating Scale (BPRS), and the Scale for the Assessment of Negative Symptoms (SANS) at drug-free baseline and after 4 weeks of neuroleptic treatment. The findings revealed that the HAM-D total score was nonspecific, while individual HAM-D subfactors provided a better index of various symptom complexes. The HAM-D contained a depressive factor that correlated strongly with the BPRS depression factor and a negative symptom factor that correlated strongly with the SANS and the BPRS negative symptom factor. These findings suggest the need to utilize specific assessment techniques rather than global measures when assessing depression in schizophrenia.

Adolescent↗
PubMed1992

Very brief psychotherapy in the psychiatric consultation setting.

Very brief psychotherapy has emerged as a unique treatment modality in recent years. The limited time frame dictates flexibility in the choice of therapeutic technique, but there exists a need for an assessment model to link specific technique with the clinical problem. An early psychotherapeutic formulation containing three parts is the central component of the assessment model: theoretical description of the problem, immediate goal, and intervention technique. Various theories of psychopathology and therapeutic techniques can be simultaneously applied to the clinical problem. Three cases illustrate the use of this model in a consultation/liaison setting.

Adult↗
PubMed1991

Stability of positive and negative symptom constructs during neuroleptic treatment in schizophrenia.

To assess the structural stability of positive and negative symptom ratings, we rated 40 schizophrenic inpatients on the Brief Psychiatric Rating Scale (BPRS) and the Scale for the Assessment of Negative Symptoms (SANS) at medication-free baseline and after 4 weeks of neuroleptic treatment. Positive symptom variables consisted of six BPRS items, and the negative symptom variables consisted of the five SANS subscale global scores. On principal components analysis, a three-factor, oblique-rotated solution resulted, with a negative symptom factor, a positive symptom factor, and an unstable behavioral agitation factor. The pre- and posttreatment factor loading patterns were similar. The findings suggest that BPRS-positive symptom items and the SANS measure distinct clinical dimensions and that the construct is stable, as demonstrated by minimal structural change with time.

Adult↗
PubMed1989

Attenuation of hypoxic ventilation by hyperbaric O2: effects of pressure and exposure time.

Hyperoxia affects O2 chemoreception in the highly perfused carotid bodies and causes a reduction of the ventilatory hypoxic drive (HD) as was shown for anesthetized cats and awake rats. We looked for a quantitative description of such an effect on HD as a function of both O2 pressure and exposure duration. Ventilation of rats was measured using the barometric method before and after hyperbaric O2 (HBO) exposure, at either air, 80% O2, or 4% O2. We used three exposure durations: 180, 550 and 900 min. The O2 pressure ranged between 1.2 and 3.0 ATA. At each time duration we used four to five groups of rats at a range of O2 pressures that yielded the full scale of effect on HD but avoided obvious lasting difficulties in breathing. HBO caused a reduction of breathing frequency and elevation of tidal volume in both air and 80% O2 but almost no change in minute ventilation. Hypoxic minute ventilation (4% O2) decreased after HBO, mainly through reduced frequency. HD was described by a power function of O2 pressure for each HBO duration. HD did not decline below 20% of the full control response. Ventilatory HD diminution is pictured as a function of both O2 pressure and HBO duration. The dependency of HD on exposure time and on pressure is similar to other known toxic effects of HBO.

Animals↗
PubMedDate not supplied

Alteration of corticothalamic perfusion ratios during a PTSD flashback.

We performed a single photon emission computed tomography (SPECT) study of patients with posttraumatic stress disorder (PTSD) by measuring changes in regional cerebral blood flow (rCBF) during provocation by combat stimuli. A single patient experienced an actual flashback following exposure to combat sounds, exhibiting tearfulness, diaphoresis, tachypnea, and severe agitation. Results from his SPECT study demonstrated a dramatically altered ratio of cortical to subcortical perfusion during the flashback but not during the control scan. This altered pattern, which showed a peak of activity in the thalamus, was not consistent with global rCBF changes induced by hyperventilation. The perfusion pattern during the patient's control scan was qualitatively indistinguishable from any of the SPECT scans obtained for the other patients. This single case suggests a possible role for corticothalamic dysfunction in flashbacks.

Acoustic Stimulation↗
PubMedDate not supplied

Medial frontal cortex involvement in PTSD symptoms: a SPECT study.

The regional cerebral blood flow (rCBF) responses to a combat stress-related auditory stimulus was examined in Vietnam veterans diagnosed with posttraumatic stress disorder (PTSD). Based on prior data in healthy subjects, we hypothesized that the medial prefrontal cortex may be involved in the processing of stress responses. Twelve male veterans diagnosed with PTSD, 11 age-matched, combat-exposed subjects without PTSD, and 12 healthy control subjects were studied with single-photon emission tomography and the blood flow tracer [99mTc]-HMPAO. Subjects were studied twice, while listening to combat sounds or white noise. Significant increases in the blood flow to the medial prefrontal cortex were observed in PTSD patients, but not in the control groups, which correlated at trend levels with psychophysical measures of stress response. These data support the involvement of the medial prefrontal cortex in the pathophysiology of PTSD, possibly mediating some of its symptoms.

Acoustic Stimulation↗
PubMedDate not supplied

The structure of posttraumatic stress disorder symptoms in combat veterans: a confirmatory factor analysis of the impact of event scale.

There has been controversy over the most appropriate way to define symptom clusters for posttraumatic stress disorder (PTSD). We tested the factor structure of the Impact of Event Scale (IES) in a sample of 195 male combat veterans with chronic PTSD by using confirmatory factor analysis. The two-factor model including Intrusion (i.e., unwanted memories of the event) and Avoidance (i.e., attempts to avoid reminders and numbing of emotional responsiveness) deviated significantly from good fit. However, a four-factor model, including Intrusion and Effortful Avoidance subscales, as well as Sleep Disturbance and Emotional Numbing subscales, fit significantly better. Correlations with other PTSD measures are explored and implications for the conceptualization of PTSD are discussed.

Aged↗
PubMedDate not supplied

Emotional processing in combat-related posttraumatic stress disorder: a comparison with traumatized and normal controls.

Emotional numbing (EN) symptoms are an important but poorly understood component of the response to trauma. To try to demonstrate EN, this laboratory study examined subjective and psychophysiological emotion responses to standardized visual stimuli in combat veterans with posttraumatic stress disorder (PTSD), combat veterans without PTSD, and nontraumatized controls. PTSD subjects showed no evidence of generalized reduction in subjective or psychophysiological emotion responses. In response to a subset of more evocative stimuli, PTSD subjects reported less experience of Positive Emotions, and more experience of Negative Emotions than controls. For controls, valence and arousal were uncorrelated, while they were negatively correlated for PTSD subjects. Verbal and nonverbal subjective emotion measures were positively correlated for all subject groups, but there was little correlation between subjective emotion measures and psychophysiological indices. Viewing time was positively correlated with Positive Emotions for PTSD subjects, and with Negative Emotions for combat controls.

Arousal↗