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Abstract: Background: Differences occur in certain features of childhood and adult migraine, such as the duration and location. However, few studies have been reported of the changes in other symptoms during childhood. Aims: The aims of this study were to establish the prevalence of migraine headache in children in Hungary, and to investigate the changes in prevalence of migraine and migraine symptoms in a wide paediatric age range. Methods: We conducted a school-based study with the use of a questionnaire. Results: 7361 7–18-year-old students participated. The 1-year prevalence of migraine was 12.5% (9.2% in boys and 15.4% in girls). With the criterion of a headache duration of 4 h for 15–18-year-olds and of 1 h below the age of 15, the overall prevalence decreased to 9.1%. The prevalence of migraine increased steadily from young childhood to late adolescence in both boys and girls. The frequency and duration of headache increased, whereas vomiting and nausea became less prevalent with advancing age in both genders. The prevalence of uni/bilaterality, photophobia and phonophobia increased only in girls, while that of a pulsating character did so only in boys. Conclusions: The migraine characteristics displayed by the studied population proved similar to those experienced in other countries. The duration of headache applied in the diagnosis of migraine exerts a great impact on the prevalence data. The features of migraine change with advancing age, a situation demanding consideration in studies on migraine in children of different ages. [Copyright &y& Elsevier]

Abstract: The effects of social isolation or NMDA-receptor antagonists on pain sensitivity have repeatedly been described. However, the mechanisms underlying the alterations of pain perception in these models still remain a matter of debate. Thus, we aimed to determine the long-lasting effects of subchronic ketamine treatment and social isolation on the C- and Aδ-fiber-mediated nociception. Wistar rats after weaning (21–23 days old) were either housed individually or grouped for 21 days. The animals were treated daily for 14 days with either ketamine (30 mg/kg) or saline. On the 21st day, tail-flick latency was determined at 48 °C (C-fiber activation) and 52 °C (affects mainly Aδ-fibers), and rats were rehoused. Tail-flick test was repeated 2 and 4 weeks later. On the 5th week, carrageenan-induced heat hyperalgesia was determined on paw-withdrawal test before and after morphine treatment (1, 2 or 3 mg/kg). Regarding tail-flick latencies at 48 °C, juvenile isolation, but not ketamine resulted in a significantly enhanced pain threshold (p <0.001) throughout the investigation period, while the changes at 52 °C were not significant. In addition, both isolation and ketamine treatments enhanced the antihyperalgesic effect of 2 mg/kg morphine. In summary, juvenile isolation exerts a long-lasting effect on acute heat pain sensitivity, disturbing primarily the C-fiber-linked pain pathways, suggesting a selective disruption in the parallel sensory pathways. Since both social isolation and NMDA treatment are well-known animal models of schizophrenia, our results showed that juvenile isolation but not ketamine administration can simulate hypoalgesia associated with this disease. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to investigate the earliest stages of visual information processing using electroretinography (ERG) in patients with schizophrenia and bipolar disorder and to compare these values with those of healthy control volunteers. In the acute stage of the illness, patients with schizophrenia exhibited decreased a-wave amplitude (a measure of photoreceptor function) as compared with healthy controls. In patients with bipolar disorder, ERG measures were intact. At the baseline assessment, there was a significant negative relationship between a-wave amplitude and positive symptoms. After an 8-week follow-up period, clinical symptoms showed significant improvement and the amplitude of the a-wave significantly increased in patients with schizophrenia. At the follow-up assessment, there was no significant difference between patients with schizophrenia and controls. These results indicate that retinal dysfunctions are specific for schizophrenia, as compared with bipolar disorder, and are confined to the acute stage of the illness. [Copyright &y& Elsevier]

Abstract: Magnocellular (M) and parvocellular (P) visual pathways participate in the processing of low contrast and colors of objects, respectively. The aim of this study was to investigate M and P pathway functions in bipolar disorder during a depressive episode and after the amelioration of symptoms. Participants (17 patients with type I bipolar disorder and 20 matched healthy controls) received two vernier tasks. During the M pathway test, stimuli were dots with low luminance-contrast (5%), whereas during the P pathway test, isoluminant blue dots were presented against a yellow background. Participants were asked to detect the direction of the horizontal displacement of the dots (left or right). The assessment was performed during a depressive state and during a clinically improved state after 2 months. ⁎⁎⁎During the depressive state, the patients showed significantly impaired M and P pathway functions, whereas during the clinically improved state, their performance was better and was statistically indistinguishable from that of the controls. In conclusion, M and P pathways are impaired in depressed bipolar patients. This deficit is ameliorated along with clinical improvement. Further studies are necessary to separately assess cortical and precortical stages of information-processing, and to exclude the possibility of general motivational and attentional impairments. [Copyright &y& Elsevier]

The purpose of this study was to investigate the development of visual contrast sensitivity (CS) in children between 5 and 14 years of age. Six spatial frequencies and static (0 Hz) and dynamic (8 Hz) conditions were used at photopic and scotopic luminance levels. The results revealed significant maturation of CS, which reached the adult-like values by 11–12 years of age. The development was more pronounced at low spatial frequencies (<2 cycles/degree) and in the dynamic condition. The scotopic CS exhibited slower development than the photopic CS. These results suggest the late maturation of the magnocellular visual pathway. [Copyright &y& Elsevier]

Abstract: Schizophrenia is characterized by anomalous perceptual experiences (e.g., sensory irritation, inundation, and flooding) and specific alterations in visual perception. We aimed to investigate the effects of short-term antipsychotic medication on these perceptual alterations. We assessed 28 drug-naïve first episode patients with schizophrenia and 20 matched healthy controls at baseline and follow-up 8weeks later. Contrast sensitivity was measured with steady- and pulsed-pedestal tests. Participants also received a motion coherence task, the Structured Interview for Assessing Perceptual Anomalies (SIAPA), and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Proton magnetic resonance spectroscopy was used to measure gamma-aminobutyric acid (GABA) levels in the occipital cortex (GABA/total creatine [Cr] ratio). Results revealed that, comparing baseline and follow-up values, patients with schizophrenia exhibited a marked sensitivity reduction on the steady-pedestal test at low spatial frequency. Anomalous perceptual experiences were also significantly ameliorated. Antipsychotic medications had no effect on motion perception. RBANS scores showed mild improvements. At baseline, but not at follow-up, patients with schizophrenia outperformed controls on the steady-pedestal test at low spatial frequency. The dysfunction of motion perception (higher coherence threshold in patients relative to controls) was similar at both assessments. There were reduced GABA levels in schizophrenia at both assessments, which were not related to perceptual functions. These results suggest that antipsychotics dominantly affect visual contrast sensitivity and anomalous perceptual experiences. The prominent dampening effect on low spatial frequency in the steady-pedestal test might indicate the normalization of putatively overactive magnocellular retino-geniculo-cortical pathways. [Copyright &y& Elsevier]

Abstract: Paired associates learning is impaired in both schizophrenia and amnestic mild cognitive impairment (aMCI), which may reflect hippocampal pathology. In addition, schizophrenia is characterized by the dysfunction of the retino-geniculo-striatal magnocellular (M) visual pathway. The purpose of this study was to investigate the interaction between visual perceptual and memory dysfunctions. We administered a modified version of the CANTAB paired associates learning task to patients with schizophrenia (n=20), aMCI (n=20), and two groups of matched healthy controls (n=20 for each patient group). The stimuli in the paired associates learning task biased information processing toward the M pathways (low contrast, low spatial frequency) and parvocellular (P) pathways (high contrast, high spatial frequency). Results revealed that patients with schizophrenia exhibited a more pronounced learning deficit for M-biased relative to P-biased stimuli. In aMCI, there were similar memory deficits for both types of stimuli. Orientation discrimination for M- and P-biased stimuli was intact in both groups of patients. The number of errors in the M-biased memory condition significantly and inversely correlated with the volume of the right hippocampus in schizophrenia. These results suggest an interaction between M-biased perceptual processing and short-term relational memory in schizophrenia, which may be associated with the structural alteration of the right hippocampus. [Copyright &y& Elsevier]

Abstract: Patients with schizophrenia exhibit decreased neuregulin 1 (NRG1)-stimulated AKT phosphorylation in peripheral lymphoblasts. Here, we examined this peripheral marker in monozygotic twins discordant for schizophrenia and in healthy monozygotic twins without psychiatric disorders. B lymphoblasts were stimulated with NRG1a (65 amino-acid residue recombinant protein from the epidermal growth factor [EGF] domain) for 30min. The protein isolated from the cells was analysed by Western blotting. The dependent measure was the ratio of phosphorylated AKT (pAKT) and total AKT at baseline (without NRG1 stimulation) and after NRG1 stimulation (pAKT/AKT). The results revealed that in the case of the unaffected co-twins of patients with schizophrenia, NRG1-stimulated pAKT/AKT ratio was in between the values of their co-twins with schizophrenia and that of the healthy control twin pairs. When the affected twins with schizophrenia were compared with their unaffected co-twins using a Mann–Whitney U-test, we found significantly lower NRG1-induced pAKT/AKT ratios in the patients relative to their unaffected co-twins (p =0.004). However, using a more conservative analysis (Kruskal–Wallis ANOVA followed tests for multiple comparisons), this difference was not significant. The unaffected co-twins of patients with schizophrenia did not differ significantly from the healthy control twins. In the baseline condition, the pAKT/AKT ratios were similar in all groups. These results indicate that impaired AKT-related intracellular signaling is partly related to the developed illness and cannot fully be explained by the genetic background of schizophrenia. [Copyright &y& Elsevier]

Abstract: Previous studies indicated that neuropsychological impairments are potential endophenotypes of schizophrenia. However, the sensitivity of these procedures is not sufficient and their brain substrates are poorly defined. The aim of this study was to measure the behavioral performance of siblings of schizophrenia patients and controls on a novel feature uncertainty (FU) task that selectively activates dorsal anterior cingulate cortex relative to orientation (OR) and spatial frequency (SF) discrimination. During the FU task, two subsequent sinusoidal gratings are presented and participants are asked to remember both the OR and SF of the gratings. After the disappearance of the gratings, a color cue signifies the perceptual dimension (OR or SF) to discriminate. Results revealed that the siblings of schizophrenia patients (n =25) showed a selective deficit on the FU task as compared with controls (n =20). The FU deficit was more severe than that found on neuropsychological tests of executive functions, psychomotor speed, and verbal memory. These results suggest that anterior cingulate dysfunction is a potential endophenotype of schizophrenia. [Copyright &y& Elsevier]

The aim of this study was to investigate lateral connectivity in early visual cortex of schizophrenia patients. Contrast thresholds were measured for centrally presented Gabor patches which were surrounded by two collinear or orthogonal flankers. The healthy subjects (n=15) showed lower contrast thresholds for central Gabor patches when collinear flankers were presented. This effect was significantly reduced in unmedicated highly functioning schizophrenia patients (n=20) who performed normally on the continuous performance test. The performance of the patients did not correlate with the positive and negative symptoms. The facilitation effect of collinear flankers is believed to reflect lateral interactions between feature-specific units in early visual cortex (V1). Our results therefore suggest abnormal lateral interactions in early visual cortex of schizophrenia patients. [Copyright &y& Elsevier]

Tourette syndrome (TS) is characterised by stereotyped involuntary movements, called tics. Some evidence suggests that structural and functional abnormalities of the basal ganglia may explain these motor symptoms. In this study, the probabilistic classification learning (PCL) test was used to evaluate basal ganglia functions in 10 children with less severe tics (Yale Global Tic Severity Scale (YGTSS) scores<30) and in 10 children with more severe symptoms (YGTSS score>30). In the PCL task, participants are asked to decide whether different combinations of four geometric forms (cues) predict rainy or sunny weather. Each cue is probabilistically related to a weather outcome, and feedback is provided after each decision. After completion of the probabilistic stimulus-response learning procedure, subjects received a transfer test to assess explicit knowledge about the cues. The children with TS exhibited impaired learning in the PCL task in comparison with the 20 healthy control subjects. This impairment was more pronounced in the TS patients with severe symptoms, and there was a significant negative relationship between the final classification performance and the YGTSS scores. The patients showed normal learning in the transfer test. These results suggest that the neostriatal habit learning system, which may play a central role in the acquisition of probabilistic associations, is dysfunctional in TS, especially in the case of more severe motor symptoms. The classification performance and the severity of tics were independent of the explicit knowledge obtained during the test. [Copyright &y& Elsevier]

Recent studies indicate that category learning is mediated by multiple neuronal systems. It has been shown that patients with marked impairments in executive functions, explicit memory and procedural learning can categorize the exemplars and prototype of a previously trained category. Simple, self-organizing neuronal networks can explain prototype learning and related dysfunctions in Alzheimer''s disease, and provide a model of how prototype learning is mediated by circumscribed mechanisms in the visual cortex. [ABSTRACT FROM AUTHOR]

This study focuses on the important question whether brain activity recorded from anesthetized, paralyzed animals is comparable to that recorded from awake, behaving ones. We compared neuronal activity recorded from the caudate nucleus (CN) of two halothane-anesthetized, paralyzed and two awake, behaving cats. In both models, extracellular recordings were made from the CN during static and dynamic visual stimulation. The anesthesia was maintained during the recordings by a gaseous mixture of air and halothane (1.0%). The behaving animals were trained to perform a visual fixation task. Based on their electrophysiological properties, the recorded CN neurons were separated into three different classes: phasically active (PANs), high firing (HFNs), and tonically active (TANs) neurons. Halothane anesthesia significantly decreased the background activity of the CN neurons in all three classes. The anesthesia had the most remarkable suppressive effect on PANs, where the background activity was consistently under 1 spike/s. The analysis of these responses was almost impossible due to the extremely low activity. The evoked responses during both static and dynamic visual stimulation were obvious in the behaving cats. On the other hand, only weak visual responses were found in some neurons of halothane anesthetized cats. These results show that halothane gas anesthesia has a marked suppressive effect on the feline CN. We suggest that for the purposes of the visual and related multisensory/sensorimotor electrophysiological exploration of the CN, behaving animal models are preferable over anesthetized ones. [ABSTRACT FROM AUTHOR]

The question regarding the exact function of the primary visual cortex (V1) in vision has been around ever since the description of residual vision after damage to this cortical area by Riddoch in 1917. In 2002, Schoenfeld and colleagues proposed that V1 can be saturated by flashes of light, by which the function of V1-bypassing visual pathways can be “unmasked”. The Schoenfeld group found that light flashes applied on stimulus onset led to the elevation of brightness increment detection thresholds, but left motion detection thresholds unaltered. Although the proposed method (i.e. the use of light flashes to induce refractoriness in V1) could be a simple, cheap and elegant way of exploring V1 functions, no study has followed up on this. Therefore it is not known if it works at all with other types of stimuli. For that reason, we decided to revisit the idea in a modified form. Global form and motion perception thresholds were assessed with static Glass pattern stimuli and random dot kinematograms, with and without 12 Hz flickering light stimulation. Global motion thresholds were almost unaltered by flickering stimulation, while a significant threshold elevation was caused in the global form perception task. The strongest conclusion allowed by our data is that simultaneous flickering photostimulation elevates global form perception thresholds but not global motion perception thresholds. This is in some way related to the refractoriness generated in an unsatisfactorily defined part of V1. We suggest that this does not necessarily reflect the activity of V1-bypassing pathways, and propose that the application of light flashes is a method that deserves more attention in the exploration of the V1-dependent and independent elements of visual consciousness in human subjects. [ABSTRACT FROM AUTHOR]

Abstract: Capsaicin desensitization leads to behavioral changes, some of which are related to schizophrenia, but investigations into these effects have been scarce. The goal of this study was to characterize the consequences of juvenile capsaicin desensitization on different functions: acute and inflammation-induced thermal and mechanical sensitivity, urinary bladder capacity and thermoregulation, and also on the potentially schizophrenia-related impairments in sensory-motor gating, motor activity and cognitive functioning. Male Wistar rats desensitized with increasing doses of subcutaneous capsaicin after weaning were investigated. Heat and mechanical pain sensitivity did not change significantly; however, morphine produced a prolonged decrease in the nociceptive response to inflammation in desensitized animals. Ultrasound examination of the bladder revealed enhanced bladder volume in treated animals. Capsaicin-treated animals had higher body temperature at 22°C in both dark and light periods, and they also showed prolonged hyperthermia in new environmental circumstances. Warm environment induced a profound impairment of thermoregulation in desensitized animals. The treated animals also showed higher levels of activity during the active phase and at both cool and warm temperatures. The amplitude of the responses to auditory stimuli and prepulse inhibition did not differ between the two groups, but the desensitized animals showed learning impairments in the novel object recognition test. These results suggest that juvenile capsaicin desensitization leads to sustained changes in several functions that may be related to schizophrenia. We propose that capsaicin desensitization, together with other interventions, may lead to an improved chronic animal model of schizophrenia. [Copyright &y& Elsevier]

Abstract: Recent morphological and physiological studies support the assumption that the extrageniculate ascending tectofugal pathways send visual projection to the caudate nucleus (CN) in amniotes. In the present study we investigate the anatomical connection between the visual associative cortex along the anterior ectosylvian sulcus (AES) and the CN in adult domestic cats. An anterograde tracer – fluoro-dextrane-amine – was injected into the AES cortex. The distribution of labeled axons was not uniform in the CN. The majority of labeled axons and terminal like puncta was found only in a limited area in the dorsal part of the CN between the coordinates anterior 12–15. Furthermore, a retrograde tracer – choleratoxin-B – was injected into the dorsal part of the CN between anterior 12 and 13. We detected a large number of labeled neurons in the fundus and the dorsal part of the AES between the coordinates anterior 12–14. Based upon our recent results we argue that there is a direct monosynaptic connection between the visual associative cortex along the AES and the CN. Beside the posterior thalamus, the AES cortex should also participate in the transmission of the tectal visual information to the CN. This pathway is likely to convey complex information containing both sensory and motor components toward the basal ganglia, which supports their integrative function in visuomotor actions such as motion and novelty detection and saccade generation. [Copyright &y& Elsevier]

Abstract: Recent studies stress the importance of the caudate nucleus in visual information processing. Although the processing of moving visual signals depends upon the capability of a system to integrate spatial and temporal information, no study has investigated the spectral receptive field organization of the caudate nucleus neurons yet. Therefore, we tested caudate neurons of the feline brain by extracellular single-cell recording applying drifting sinewave gratings of various spatial and temporal frequencies, and reconstructed their spectral receptive fields by plotting their responsiveness as a function of different combinations of spatial and temporal frequencies. The majority of the caudate cells (74%) exhibited peak tuning, which means that their spatio-temporal frequency response profile had a characteristic region of increased activity with a single maximum in the spatio-temporal frequency domain. In one-quarter of the recorded caudate neurons ridge tuning was found, where the region of increased activity, forming an elongated ridge of maximal sensitivity parallel or angled to the spatial or the temporal frequency axis, indicating temporal (16%), spatial (5%) or speed (5%) tuning, respectively. The velocity preference of the ridge tuned caudate nucleus neurons is significantly lower than that of the peak tuned neurons. The peak tuned neuron could encode high velocities, while the ridge tuned neurons were responsible for the detection of moderate and lower velocities. Based upon our results, we suggest that the wide variety of spatio-temporal frequency response profiles might represent different functional neuronal groups within the caudate nucleus that subserve different behaviors to meet various environmental requirements. [Copyright &y& Elsevier]

Abstract: It has been suggested that visual contrast sensitivity and contour integration functions exhibit a late maturation during adolescence. However, the relationship between these functions has not been investigated. The aim of this study was to assess the development of visual contrast sensitivity and contour integration in 152 healthy volunteers aged between 5 and 30 years. The results revealed a significant maturation of contrast sensitivity at low spatial frequencies (0.5, 1.2, and 1.9cycles/degree) and contour integration. The largest developmental step was observed for both contrast sensitivity and contour integration tasks when the 5–8-year olds were compared with the 9–11-year olds. There was a significant correlation between the development of low spatial frequency contrast sensitivity and contour integration. These results raise the possibility that the development of low spatial frequency processing may affect attentional mechanisms, which may have an impact on early contour integration. [Copyright &y& Elsevier]

Abstract: The suprageniculate nucleus (Sg) of the feline thalamus, which subserves largely unimodal sensory and orientation behavior, receives input from the deep layers of the superior colliculus (SC), and projects to the suprasylvian cortical areas, such as the anterior ectosylvian visual area and the insular visual area (IVA), which contain visually responsive neurons. Through a double tract-tracing procedure involving the injection of wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) into the IVA and the injection of kainic acid into the SC, this study sought to determine the nature of the synaptic relationship between the SC afferents and the thalamo-cortical projection neurons. WGA-HRP injections labeled numerous neurons in the Sg, while kainic acid injections destroyed many tectothalamic terminals in the Sg. The distributions of the WGA-HRP-labeled neurons and the degenerated axon terminals overlapped in the dorsal part of the Sg. Electron microscopic observations demonstrated that the degenerated axon terminals made synaptic contacts with the dendrites of the WGA-HRP-labeled neurons in this overlapping region of the Sg. These results provide the first anatomical evidence that the Sg may play a role in the key relay of visual information from the SC to the IVA, within an identified extrageniculo-cortical pathway. [Copyright &y& Elsevier]

Abstract: Neuregulin 1 (NRG1) has been implicated in the pathophysiology of psychotic disorders. NRG1 exerts its effects via the Ras-MAPK and phosphatidylinositol-3 kinase-protein kinase B (PI3K-PKB/AKT) intracellular signaling pathways through ErbB receptors. The aim of this study was to investigate the relationship between NRG1-stimulated AKT phosphorylation and neurocognitive functions in patients with schizophrenia and in patients with other psychotic disorders. B lymphoblasts of patients (n =40) and controls (n =20) were stimulated with NRG1a (65 amino-acid residue recombinant protein from the epidermal growth factor [EGF] domain) for 30-min. The protein isolated from the cells was analyzed by Western blotting. The dependent measure was the ratio of phosphorylated AKT (pAKT) and total AKT at baseline (without NRG1 stimulation) and after NRG1 stimulation (pAKT/AKT). The neurocognitive functions (attention, immediate and long-term memory, language, visual-spatial skills) were evaluated by the repeatable brief assessment of neuropsychological status (RBANS) battery. The results revealed a significantly reduced pAKT/AKT ratio in patients with schizophrenia as compared with healthy controls and with patients with other psychotic disorders. The patients with other psychotic disorders did not differ from the healthy controls. Despite the fact that neurocognitive functions were significantly impaired in the patients, these functions did not reveal significant correlations with the pAKT/AKT ratio. In conclusion, NRG1-induced AKT phosphorylation is decreased in schizophrenia but not in other psychotic disorders. This peripheral marker is not related to neurocognitive functions. [Copyright &y& Elsevier]

Abstract: Although the visual perception depends on the integration of spatial and temporal information, no knowledge is available concerning the responsiveness of neurons in the intermediate layers of the superior colliculus (SCi) to extended visual grating stimuli. Accordingly, we set out to investigate the responsiveness of these neurons in halothane-anesthetized cats to drifting sinewave gratings at various spatial and temporal frequencies. The SCi units responded optimally to gratings of low spatial frequencies (none of the analyzed SCi units exhibited maximal activity to spatial frequencies higher than 0.3c/deg) and exhibited low spatial resolution and narrow spatial frequency tuning. On the other hand, the SCi neurons preferred high temporal frequencies and exhibited high temporal resolution. Thus, the SCi neurons seem to be good spatio–temporal filters of visual information in the low spatial and high temporal frequency domain. Based upon the above summarized results we suggest that the SCi units can detect large contours moving at high velocities well, but are unable to distinguish small details. This is in line with the generally held view that the SCi could possess visuomotor function, such as organizing the complex, sensory-guided oculomotor and skeletomotor responses during the self-motion of the animal. [Copyright &y& Elsevier]

Abstract: Both anandamide and adenosine have significant roles in pain mechanisms, but no data are available concerning their interaction at the spinal level. The goal of this study was to determine how adenosine and the adenosine receptor antagonist caffeine affect the antinociceptive effect of anandamide. The pain sensitivity was assessed by the acute tail-flick test and by paw withdrawal test after carrageenan-induced inflammation. The substances were administered intrathecally to male Wistar rats. Anandamide alone (1, 30 and 100 μg) dose-dependently decreased the hyperalgesia, however it had low potency in the tail-flick test. Neither adenosine (100 μg) nor caffeine (400 μg) alone changed the pain sensitivity markedly. Their combination caused a short-lasting antihyperalgesia, but it did not influence the tail-flick latency. Both adenosine and caffeine decreased the antihyperalgesic potential of 100 μg anandamide, while adenosine–caffeine pretreatment temporarily enhanced its effect. As regards acute heat pain sensitivity, no combination with anandamide influenced the effect of anandamide. These findings provide new data concerning the interaction between two endogenous ligands and caffeine. Since these substances may exert effects on several receptors and/or systems, their interaction in vivo must be very complex and the net outcome after their coadministration could not been predicted from the in vitro results. [Copyright &y& Elsevier]

Abstract: Evidence suggests that dopaminergic mechanisms in the basal ganglia (BG) are important in the learning of sequential associations. To test the specificity of this hypothesis, we assessed never-medicated patients with Parkinson''s disease (PD) and amnestic mild cognitive impairment (aMCI) using a chaining task. In the training phase of the chaining task, each link in a sequence of stimuli leading to reward is trained step-by-step using feedback after each decision, until the complete sequence is learned. In the probe phase of the chaining task, the context of stimulus-response associations must be used (the position of the associations in the sequence). Results revealed that patients with PD showed impaired learning during the training phase of the chaining task, but their performance was spared in the probe phase. In contrast, patients with aMCI with prominent medial temporal lobe (MTL) dysfunctions showed intact learning during the training phase of the chaining task, but their performance was impaired in the probe phase of the chaining task. These results indicate that when dopaminergic mechanisms in the BG are dysfunctional, series of stimulus-response associations are less efficiently acquired, but their sequential manner is maintained. In contrast, MTL dysfunctions may result in a non-sequential learning of associations, which may indicate a loss of contextual information. [Copyright &y& Elsevier]

Abstract: This study was designed to investigate the relationship between abnormal neurological signs, visual contrast sensitivity, and the deficit syndrome of schizophrenia. Visual contrast sensitivity for counterphase-modulated low spatial frequency gratings was measured in 32 non-deficit and 12 deficit schizophrenia patients and 20 healthy controls subjects. Abnormal neurological signs were evaluated with the Neurological Evaluation Scale (NES). Compared with the controls, patients with schizophrenia displayed impaired visual contrast sensitivity, which was associated with sensory integration deficits, as measured with the NES. The deficit syndrome was predicted by negative symptoms and sensory integration deficits. These results suggest that early-stage perceptual dysfunctions, which may reflect the abnormality of precortical magnocellular visual pathways, are related to a specific group of abnormal neurological signs. [Copyright &y& Elsevier]

Abstract: Objective: Nonarteritic ischemic optic neuropathy (NAION) is one of the most frequent causes of sudden visual loss in middle-aged or elderly patients. Although several electrophysiological methods are available for an objective evaluation of the visual deficits, these are not generally used in the assessment of the clinical condition of NAION patients. To evaluate the severity of the optic nerve and retinal damage, electrophysiological tests were performed on 8 patients with NAION. Methods: Visual evoked potentials (VEPs), scotopic, photopic and flicker electroretinograms (ERGs), multifocal ERGs and pattern ERGs were recorded. Results: The results demonstrated that the VEPs fairly reliably reflected the visual loss caused by NAION. The VEPs were extinguished in cases with a serious visual acuity loss, while a decrease in amplitude and a lengthening of the P100 latency were observed in cases with good visual acuity and a severe visual field loss and in the nonattacked fellow eye of the patients with monocular involvement. The pattern ERGs failed to show signs of retrograde degeneration. The photopic, scotopic and flicker ERGs, and the oscillatory potentials (OPs) were close to normal in these NAION patients. Conclusions: Our observations permit the conclusion that electrophysiological methods can provide an objective indication of the clinical condition of these patients. The new data obtained promote an understanding of the pathomechanism of the disease. Significance: Electrophysiological tests are suitable for monitoring of the progression of the disease in NAION patients. [Copyright &y& Elsevier]

Abstract: This study describes the visual information coding ability of single neurons in the suprageniculate nucleus (Sg), and provides new data concerning the visual information flow in the suprageniculate/anterior ectosylvian pathways of the feline brain. The visual receptive fields of the Sg neurons have an internal structure rather similar to that described earlier in the anterior ectosylvian visual area (AEV). The majority of the Sg units can provide information via their discharge rate at the site of the visual stimulus within their large receptive fields. This suggests that they may serve as panoramic localizers. The sites of maximum responsivity of the Sg neurons are distributed over the whole investigated part of the visual field. There is no significant difference between the distributions of spatial location of maximum sensitivity of the AEV and the Sg neurons. The mean visual response latency of the Sg units was found to be significantly shorter than the mean latency of the AEV neurons, but there was no difference between the shortest latency values of the thalamic and the cortical single-units. This suggests that the visual information flows predominantly from the Sg to the AEV, though the cortico-thalamic route is also active. The Sg seems to represent a thalamic nucleus rather similar in function to both the first-order relays and the higher-order thalamic nuclei. These results, together with the fact that the superior colliculus provides the common ascending source of information to the suprageniculate/anterior ectosylvian pathway, suggest a unique function of the AEV and the Sg in sensorimotor integration. [Copyright &y& Elsevier]

Abstract: Impaired neuronal energy metabolism, oxidative changes and microvascular abnormalities lead to altered lactate levels in Alzheimer''s dementia. The aim of the present study was to assess whether intravenous sodium-lactate, a metabolic alternative and vasodilator that is thought to improve cognition, advances the cognitive performance of Alzheimer patients. Semantic categorization paradigm was used to present the electrophysiological correlates of natural scene categorization of Alzheimer patients before and after intravenous saline or sodium-lactate infusion. Mean amplitudes of event-related potentials (ERPs) were measured in two time windows before and after the treatments; two negative components (N1 between 150 and 250ms and N2 between 400 and 600ms) and one positive component (P2 between 250 and 400ms) were identified. The negative components were more negative for the non-animal trials than for the animal trials while the positive component was similar for both categories. After the lactate treatment the amplitudes of the negative components became more negative mainly for the non-animal trials while the amplitude of the positive component turned more positive for the animal trials, however these changes were not significant. No changes have been observed after normal saline infusion. These results suggest that, contrary to its anticipated beneficial effects, sodium-lactate fails to significantly improve semantic categorization processes in Alzheimer''s disease and this enhancement can be detected by recording ERPs. The effect of sodium-lactate to slightly improve semantic memory might be based on its positive effect on cardio- and cerebro-vascular function and neuronal metabolism. [Copyright &y& Elsevier]

The purpose of this study was to investigate the effects of light therapy on visual contrast sensitivity in patients with seasonal affective disorder (n=10) and healthy control subjects (n=10). Static and dynamic visual contrast sensitivity was measured using a Venus system before and after 4 weeks of light therapy (10 000 lux, 30 min, 5 times a week). Light therapy increased static visual contrast sensitivity in the patients. We found no significant difference between the patients and controls either before or after light therapy. These results raise the possibility that light therapy induces retinal sensitization in seasonal affective disorder. [Copyright &y& Elsevier]

The goal of this study was to investigate the effects of endomorphin-1 on Na+,K+-ATPase activity in mouse brain synaptosome in vitro, and its antinociceptive interaction with the Na+,K+-ATPase inhibitor ouabain. Endomorphin-1 (0.1 nM–10 μM) produced a concentration-dependent (EC50: 43.19 nM, CI: 23.38–65.71 nM, Emax: 25.86%, CI: 24.53–27.20%), naloxone-reversible increase of the synaptosomal Na+,K+-ATPase activity. The intrathecally (i.t.) administered endomorphin-1 (2–20 μg) produced a dose-dependent short-lasting increase in the tail-flick latency. Ouabain itself (1–1000 ng, i.t.) did not cause antinociception. Treatment with 10 ng ouabain significantly decreased the antinociceptive effect of 2 μg endomorphin-1, but none of the other combinations did significantly differ from the endomorhin-1-treated groups. These data indicate that endomorphin-1 increases the activity of Na+,K+-ATPase in vitro but this effect may play a weak role in the antinociception induced by intrathecal endomorphin-1. [Copyright &y& Elsevier]