[Magneto-encephalographic (MEG) brain recordings during traumatic memory recall in women with post-traumatic stress disorder: A pilot study].

Aim Of The Study: The experiment studied the effects of a short duration exposure to traumatic memories using magneto-encephalography (MEG).

Patients: Nine right-handed DSM-4 PTSD patients were recruited from a unit for anxiety disorders and an organisation supporting victims of violence. In order to have a homogeneous sample, we included only women who suffered from civilian PTSD.

Eye movement desensitization and reprocessing for posttraumatic stress disorder: a pilot blinded, randomized study of stimulation type.

Background: Eye movement desensitization and reprocessing (EMDR) is becoming a recognized and accepted form of psychotherapy for posttraumatic stress disorder (PTSD). Yet, its mechanism of action remains unclear and much controversy exists about whether eye movements or other forms of bilateral kinesthetic stimulation contribute to its clinical effects beyond the exposure elements of the procedure.

Methods: Twenty-one patients with single-event PTSD (average Impact of Event Scale score: 49.

31P-MRS study of acetyl-L-carnitine treatment in geriatric depression: preliminary results.

Objective: This 12-week study of two elderly, depressed subjects investigated the effect of acetyl-L-carnitine (ALCAR) treatment on the Hamilton Depression Rating Scale (HDRS) and on measures of high-energy phosphate and membrane phospholipid metabolism.

Methods: Two mildly depressed (HDRS 15-20), non-demented male subjects 70 and 80 years old were compared with six non-demented controls (all males, mean age of 73.6 +/- 3.

Somatizing patients: part II. Practical management.

Somatization is the experiencing of physical symptoms in response to emotional distress. It is a common and costly disorder that is frustrating to patients and physicians. Successful treatment of somatization requires giving an acceptable explanation of the symptoms to the patient, avoiding unwarranted interventions and arranging brief but regular office visits so that the patient does not need to develop new symptoms in order to receive medical attention.

Somatizing patients: Part I. Practical diagnosis.

The phenomenon of somatization, which results in unexplained physical complaints, is ubiquitous in primary care settings although it often goes unrecognized. Medical training emphasizes the identification and treatment of organic problems and may leave physicians unprepared to recognize and address somatoform complaints. As a process, somatization ranges from mild stress-related symptoms to severe debilitation.

The somatizing patient.

Somatization is the experience of physical symptoms in response to emotional distress. It is common, costly, and frustrating to both the patient and physician. Successful treatment of somatization requires the physician to pursue a positive diagnosis rather than rely on a diagnosis of exclusion.

Context-processing deficits in schizophrenia: converging evidence from three theoretically motivated cognitive tasks.

To test the hypothesis that the ability to actively represent and maintain context information in a central function of working memory and that a disturbance in this function contributes to cognitive deficits in schizophrenia, the authors modified 3 tasks--the AX version of the Continuous Performance Test, Stroop, and a lexical disambiguation task--and administered them to patients with schizophrenia as well as to depressed and healthy controls. The results suggest an accentuation of deficits in patients with schizophrenia in context-sensitive conditions and cross-task correlations of performance in these conditions. However, the results do not definitively eliminate the possibility of a generalized deficit.

The role of locus coeruleus in the regulation of cognitive performance.

Noradrenergic locus coeruleus (LC) neurons were recorded in monkeys performing a visual discrimination task, and a computational model was developed addressing the role of the LC brain system in cognitive performance. Changes in spontaneous and stimulus-induced patterns of LC activity correlated closely with fluctuations in behavioral performance. The model explains these fluctuations in terms of changes in electrotonic coupling among LC neurons and predicts improved performance during epochs of high coupling and synchronized LC firing.

Prevalence of posttraumatic stress disorder and major depressive disorder in Tibetan refugee children.

Objective: In an exploratory survey the prevalence of posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) was estimated in children who escaped from Tibet and found refuge in Tibetan settlements in India.

Method: As part of an exploratory mission of the international medical relief organization Doctors Without Borders (Medecins Sans Frontieres), 61 randomly selected children from four group homes of the Tibetan Children Village in Dharamsala, India, were interviewed for symptoms of PTSD and MDD.

Results: 11.

Selective pharmacological activation of limbic structures in human volunteers: a positron emission tomography study.

Using a pharmacological probe, procaine hydrochloride, the authors elicited consistent and selective activation of anterior limbic and paralimbic structures in normal human volunteers as documented by H215O positron emission tomography. This activation was associated with a range of emotional, somatic, and visceral experiences, often similar to those experienced during the aura of temporal lobe epilepsy. Several subjects also experienced panic attacks.

Dopamine and the mechanisms of cognition: Part II. D-amphetamine effects in human subjects performing a selective attention task.

Background: A neural network computer model described in a companion paper predicted the effects of increased dopamine transmission on selective attention under two different hypotheses.

Methods: To evaluate these predictions we conducted an empirical study in human subjects of D-amphetamine effects on performance of the Eriksen response competition task. Ten healthy volunteers were tested before and after placebo or D-amphetamine in a double-blind cross-over design.

Dopamine and the mechanisms of cognition: Part I. A neural network model predicting dopamine effects on selective attention.

Background: Dopamine affects neural information processing, cognition, and behavior; however, the mechanisms through which these three levels of function are affected have remained unspecified. We present a parallel-distributed processing model of dopamine effects on neural ensembles that accounts for effects on human performance in a selective attention task.

Methods: Task performance is stimulated using principles and mechanisms that capture salient aspects of information processing in neural ensembles.

Computational modeling of emotion: explorations through the anatomy and physiology of fear conditioning.

Recent discoveries about the neural system and cellular mechanisms in pathways mediating classical fear conditioning have provided a foundation for pursuing concurrent connectionist models of this form of emotional learning. The models described are constrained by the known anatomy underlying the behavior being simulated. To date, implementations capture salient features of fear learning, both at the level of behavior and at the level of single cells, and additionally make use of generic biophysical constraints to mimic fundamental excitatory and inhibitory transmission properties.

Stimulus generalization of fear responses: effects of auditory cortex lesions in a computational model and in rats.

The conditioning of fear responses to a simple acoustic stimulus (pure tone) paired with footshock can be mediated by the transmission of auditory information to the lateral nucleus of the amygdala from either the auditory thalamus or the auditory cortex. We examined the processing capacity of the thalamo-amygdala pathway by making lesions of the auditory cortex and testing the extent to which conditioned fear responses generalized to tones other than the one paired with footshock. Two studies were performed, one in an anatomically constrained computational model of the fear conditioning network and the other in rats.

Pharmacologic activation of limbic structures and neuroimaging studies of emotions.

Two primary paradigms have been employed to study the neurobiological basis of human emotions. These are induced emotions in normal subjects and the comparison of patients suffering from emotional disorders with normal control subjects. These traditional methods, which have limitations, may be complemented by a third approach: the experimental elicitation of affect through pharmacologic limbic stimulation with intravenous procaine hydrochloride.

Anxiety disorders and the syndrome of chest pain with normal coronary arteries: prevalence and pathophysiology.

Recurrent chest pain in the presence of normal coronary arteries is a common and perplexing problem in primary care medicine and cardiology and is associated with significant morbidity and health care utilization. A series of carefully controlled prospective studies conducted over the past decade have suggested a strong association between this syndrome and the presence of anxiety disorders. Thirty percent to 50% of patients with recurrent chest pain and normal coronary arteries meet criteria for panic disorder.

Schizophrenic deficits in the processing of context. A test of a theoretical model.

Background: Schizophrenic patients show various deficits in cognitive functions that have been difficult to understand in terms of a common unifying hypothesis. Previously described neural network models of cognitive tasks suggest that several schizophrenic performance deficits may be related to a single function-an impairment in maintaining contextual information over time and in using that information to inhibit inappropriate responses.

Methods: We tested first-episode schizophrenic patients and patients later in the course of their illness on a new variant of the Continuous Performance Test designed specifically to elicit deficits in the processing of contextual information.

Semantic priming in schizophrenia: an examination of spreading activation using word pronunciation and multiple SOAs.

Semantic priming in word pronunciation was examined at 5 stimulus onset asynchronies (SOAs) in 75 medicated and 25 unmedicated people with schizophrenia (SCZ) and in 10 depressed and 28 normal controls. At SOAs < 950 ms, SCZ displayed priming similar to that of normal and depressed controls. At the 950-ms SOA, SCZ displayed less priming than controls.

A neural network simulation of hallucinated "voices" and associated speech perception impairments in schizophrenic patients.

The mechanism of hallucinated speech, a symptom commonly reported by schizophrenic patients, is unknown. The hypothesis that these hallucinations arise from pathologically altered working memory underlying speech perception was explored. A neural network computer simulation of contextually guided sequential word detection based on Elman (1990a,b) was studied.

An anatomically constrained neural network model of fear conditioning.

Conditioning of fear reactions to an auditory conditioned stimulus (CS) paired with a footshock unconditioned stimulus (US) involves CS transmission to the amygdala from the auditory thalamus, the auditory cortex, or both. This article presents a simple neural network model of this neural system. The model consists of modules of mutually inhibitory nonlinear units representing the different relevant anatomical structures of the thalamo-amygdala and thalamo-corticoamygdala circuitry.

Neuroleptic effects on acquisition and performance of learned behaviors: a reinterpretation.

It is well-established that dopamine facilitates motor responsiveness. However, neuroleptics--drugs that block dopaminergic transmission--do not affect equally motor responses to environmental stimuli: responses to some stimuli seem completely preserved while responses to other stimuli are greatly disturbed. For example, escape responses to a noxious stimulus are typically preserved, even when avoidance to a cue predicting the noxious stimulus is absent.

Mechanisms of spatial attention: the relation of macrostructure to microstructure in parietal neglect.

Abstract Parietal-damaged patients respond abnormally slowly to targets presented in the affected hemifield when preceded by cues in the intact hemifield. This inability to disengage attention from the ipsilesional field to reengage it in the contralesional field has been interpreted as evidence for a distinct "disengage" mechanism, localized in parietal cortex. We present a computational model that accounts for normal attentional effects by interactivity and competition among representations of different locations in space, without a dedicated "disengage" mechanism.