• Neuroinformatics

Objectives: The investigation of the CO2 laser evoked potential (LEP) modifications following a point localization task. Methods: LEPs were recorded from 10 healthy subjects in two different conditions. (1) Task condition: laser stimuli were shifted among 3 different locations on the right hand dorsum, and the subjects were asked to identify the stimulated area. The mean error rate in point localization was 4.5%. (2) Non-task condition: laser pulses were delivered on the first intermetacarpal space, and the subject was asked to count the number of stimuli. The mean error rate in counting was 5.8%. Results: In the task condition, the temporal traces contralateral to the stimulation showed an early positive component (eP, mean peak latency 83 ms) preceding the N1 negativity (mean peak latency 144 ms). At the eP peak latency, topographic maps showed a positivity highly focused on the contralateral temporal region. In the non-task recordings no reliable response was identifiable before the N1 potential. Conclusions: While no LEP component earlier than the middle-latency N1 potential can be recorded in the non-task condition, a positive response (eP) preceding the N1 component is identifiable in the contralateral temporal region during the spatial localization of painful stimuli. The eP scalp distribution is compatible with its origin from a radial source in the second somatosensory (or insular) area, thus suggesting that the opercular cortex is involved not only in the middle-latency (N1 potential), but also in early pain processing. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

Programmed cell death was studied in the superior colliculus of the developing rat brain following injections of chloramphenicol. Neonatal rats were either subject to unilateral eye removal or left untouched. Following a 3-h post-operative survival, the animals were perfused with fixatives and frozen sections of their brains were examined for apoptosis after either neutral-red staining, in situ nick-end labeling of fragmented DNA, or immunocytochemistry to activated caspase-3. Chloramphenicol induced apoptosis in control brains and potentiated cell death in deafferented superior colliculi. The results show that CMP has a general pro-apoptotic effect in the developing brain.

Abstract Intraperitoneal administration of L-threonine increased the glycine and threonine concentrations in rat spinal cord. Glycine contents also increased in synaptosomes prepared from spinal cords from threonine-pretreated animals. These findings suggest that plasma threonine concentrations normally might affect production of glycine by central nervous system neurons, and also that exogenous threonine might be useful in modifying glycinergic transmission.

Motivational abnormalities represent a key area of dysfunction in individuals with, or at risk for, schizophrenia and severely limit broad domains of functioning in these populations. The aberrant salience hypothesis posits that motivational abnormalities are the result of an over-attribution of salience to nonpleasurable stimuli but an under-attribution of salience to pleasurable ones. Consequently, people "want" what they do not "like" but do not "want" what they "like." However, it is unclear how this hypothesis manifests in schizophrenia risk beyond monetary rewards. The current research provided a multimodal investigation of the aberrant salience hypothesis in people with elevated psychotic-like experiences (PLEs) who are at risk for developing psychosis. Study 1 examined the link between liking and incentive salience using a neurobiological indicator of incentive salience (contingent negative variation/CNV) in 23 PLEs and 21 Control participants. The PLEs group showed diminished CNV reactivity to pleasant (vs. neutral) social images, which was driven by an augmented response to neutral stimuli. Study 2 examined liking, incentive salience, and conscious wanting experience using a psychological indicator of incentive salience (positive spontaneous thoughts/PSTs) in 38 PLEs and 246 Control participants. The PLEs group showed diminished correspondence between liking, PSTs, and conscious wanting across diverse reward contexts. Collectively, individuals with PLEs over-attribute salience to neutral stimuli and, to a lesser degree, under-attribute salience to rewards. Findings of the current research support abnormal salience attribution as a trait-like feature implicated in the pathophysiology and development of schizophrenia and provide valuable insights on research and treatment of this illness.

Optic flow is the stream of retinal information generated when an observer's body, head or eyes move relative to their environment, and it plays a defining role in many influential theories of active perception. Traditionally, studies of optic flow have used artificially generated flow in the absence of the body-based cues typically coincident with self-motion (e.g. proprioceptive, efference copy, and vestibular). While optic flow alone can be used to judge the direction, speed and magnitude of self-motion, little is known about the precise extent to which it is used during natural locomotor behaviours such as walking. In this study, walked distances were estimated in an open outdoor environment. This study employed two novel complementary techniques to dissociate the contributions of optic flow from body-based cues when estimating distance travelled in a flat, open, outdoor environment void of distinct proximal visual landmarks. First, lenses were used to magnify or minify the visual environment. Second, two walked distances were presented in succession and were either the same or different in magnitude; vision was either present or absent in each. A computational model was developed based on the results of both experiments. Highly convergent cue-weighting values were observed, indicating that the brain consistently weighted body-based cues about twice as high as optic flow, the combination of the two cues being additive. The current experiments represent some of the first to isolate and quantify the contributions of optic flow during natural human locomotor behaviour.

The aim of this work was to estimate excessive somnolence and frequency of episodes of dozing off during driving a car in patients with obstructive sleep apnea. Result of questionnaire and polysomnographic investigations were analysed in a group of 503 patients. Mean age for the whole group was 49.2 +/- 9.7 of years, BMI 32.1 +/- 1.4 kg/m2 and the value for apnea and hypopnea index 45.4 +/- 24.8. Excessive somnolence during driving was reported by 49.1% of patients. 31.2% of the group notified at least one episode of falling asleep while driving a car. Sleepy drivers (group A) were significantly younger (46.5 +/- 9.2 vs 50 +/- 9.8 years) and had higher values of BMI (34.1 +/- 7 vs 31.1 +/- 5.5 kg/m2) than the others (group B) Results of polysomnographic investigation showed more severe sleep apnea in the group A. Mean value of AHI for this group was 52.5 +/- 26.1 vs 41.6 +/- 23.5 in the group B. Besides, somnolence in many other practical situations was more often considered as a serious problem in the group A.

The first objective of this article is to summarize the history of electroconvulsive therapy (ECT) in psychiatry in order to highlight the transition from clinical level of evidence based on phenomenological descriptions to controlled trial establishing causal relationship. The second objective is to apply the criteria of causation for ECT, to focus on the dose-effect relationship criteria, and thus to analyze the conditions of application of these criteria for ECT.A literature review exploring the use of electricity, ECT and electroencephalography (EEG) in psychiatry was conducted. The publications were identified from the Pubmed and GoogleScholar electronic databases. The scientific literature search of international articles was performed in July 2016.In 1784, a Royal commission established in France by King Louis XVI tested Mesmer's claims concerning animal magnetism. By doing that, the commission, including such prominent scientists as the chemist Anton Lavoisier and the scientist and researcher on electricity and therapeutics Benjamin Franklin, played a central role in establishing the criteria needed to assess the level of evidence of electrical therapeutics in psychiatry. Surprisingly, it is possible to identify the classical Bradford Hill criteria of causation in the report of the commission, except the dose-effect relationship criteria. Since then, it has been conducted blinded randomized controlled trials that confirmed the effectiveness of ECT against ECT placebos for the treatment of psychiatric disorders. At present, the dose-effect relationship criteria can be analyzed through an EEG quality assessment of ECT-induced seizures.EEG quality assessment includes several indices: TSLOW (time to onset of seizure activity ≤5Hz, seconds), peak mid-ictal amplitude (mm), regularity (intensity or morphology of the seizure (0-6)), stereotypy (global seizure patterning, 0-3) and post-ictal suppression (0-3). A manual rating sheet is needed to score theses indices. Such manual rating with example of EEG segments recording is proposed in this article. Additional studies are needed to validate this manual, to better establish the dose-response relationship for the ECT, and thus strengthen the position of the EEG as a central element for clinical good practice for ECT.

Previous studies have shown that appetitive motivation enhances episodic memory formation via a network including the substantia nigra/ventral tegmental area (SN/VTA), striatum and hippocampus. This functional magnetic resonance imaging (fMRI) study now contrasted the impact of aversive and appetitive motivation on episodic long-term memory. Cue pictures predicted monetary reward or punishment in alternating experimental blocks. One day later, episodic memory for the cue pictures was tested. We also investigated how the neural processing of appetitive and aversive motivation and episodic memory were modulated by dopaminergic mechanisms. To that end, participants were selected on the basis of their genotype for a variable number of tandem repeat polymorphism of the dopamine transporter (DAT) gene. The resulting groups were carefully matched for the 5-HTTLPR polymorphism of the serotonin transporter gene. Recognition memory for cues from both motivational categories was enhanced in participants homozygous for the 10-repeat allele of the DAT, the functional effects of which are not known yet, but not in heterozygous subjects. In comparison with heterozygous participants, 10-repeat homozygous participants also showed increased striatal activity for anticipation of motivational outcomes compared to neutral outcomes. In a subsequent memory analysis, encoding activity in striatum and hippocampus was found to be higher for later recognized items in 10-repeat homozygotes compared to 9/10-repeat heterozygotes. These findings suggest that processing of appetitive and aversive motivation in the human striatum involve the dopaminergic system and that dopamine plays a role in memory for both types of motivational information. In accordance with animal studies, these data support the idea that encoding of motivational events depends on dopaminergic processes in the hippocampus.

Abstract Background Somatosensory evoked potentials (SSEP) are being used for the investigation and monitoring of the integrity of neural pathways during surgical procedures. Intraoperative neurophysiologic monitoring is affected by the type of anesthetic agents. Remifentanil is supposed to produce minimal or no changes in SSEP amplitude and latency. This study aims to investigate whether high doses of remifentanil influence the SSEP during spinal surgery under total intravenous anesthesia. Methods Ten patients underwent spinal surgery. Anesthesia was induced with propofol (2 mg/Kg), fentanyl (2 mcg/Kg) and a single dose of cis-atracurium (0.15 mg/Kg), followed by infusion of 0.8 mcg/kg/min of remifentanil and propofol (30-50 mcg/kg/min). The depth of anesthesia was monitored by Bispectral Index (BIS) and an adequate level (40-50) of anesthesia was maintained. Somatosensory evoked potentials (SSEPs) were recorded intraoperatively from the tibial nerve (P37) 15 min before initiation of remifentanil infusion. Data were analysed over that period. Results Remifentanil induced prolongation of the tibial SSEP latency which however was not significant (p > 0.05). The suppression of the amplitude was significant (p Conclusion Remifentanil in high doses induces significant changes in SSEP components that should be taken under consideration during intraoperative neuromonitoring.

Homonymous hemianopia due to lateral geniculate body (LGB) lesion has rarely been reported. It is difficult to detect the LGB lesion by neuroimaging. We report two patients with characteristic homonymous hemianopia due to cerebral infarction of the LGB. In both patients, Goldmann perimetry showed incongruous and wedge-shaped homonymous hemianopia, and magnetic resonance imaging demonstrated infarction of the LGB. In addition, occlusion of the lateral posterior choroidal artery was confirmed by magnetic resonance angiography in one of these patients. To diagnose of a LGB lesion, we should carefully observe characteristic visual field defects, accompanying neurologic symptoms, and neuroimaging findings, including magnetic resonance angiography.