Evoked potential topography in major depression. I. Comparisons with nonpatients and schizophrenics.

This study compared evoked potential (EP) topography in major depression (MD), schizophrenia and nonpatient controls. EPs to four kinds of stimuli were recorded from 15 locations. Patients were 69 MDs and 52 schizophrenics, currently unmedicated. EP waveforms of 195 controls were subjected to principal component factor analysis (PCA). The structures of 32 factors so extracted have been shown to encompass the data space of disparate groups; they were used to compute factor scores for all subjects. Age- and gender-matched groups were compared. Factor scores were normalized across leads (Z-transform) to distinguish between topographic and mean level differences. Topographic differences (P < 0.05) between MD and controls were demonstrated for scores of 8 factors, with 2 others at P = 0.053. Unlike those for schizophrenia/control comparisons, these topographic differences did not converge regionally in MD. EP findings were not related to duration of withdrawal from drugs. There were few differences between bipolar and unipolar patients. Topographies of 5 factors differed between MDs and schizophrenics; these involved all modalities and reflected long latency, cognition-related events, such as P300. These topographic differences were antero-posterior (AP); values were greater posteriorly in MDs and anteriorly in schizophrenics. Deviant AP gradients appear specific to MD; gradients were similar in schizophrenics and controls.     

Event-Related Potential Indices of Selective Attention and Cortical Lateralization in Schizophrenia

Auditory event-related potentials (ERPs) from a multidimensional selective attention task were recorded from 10 unmedicated schizophrenic patients and 10 age- and sex-matched healthy controls. Tone pip stimuli varying on the dimensions of pitch (high or low) and location (left or right ear) formed four 'channels' of stimuli: left low, left high, right low, and right high. The pitch difference was considerably more difficult to discriminate than the location difference. Subjects were instructed to pay attention to a designated channel and press a button whenever they detected a long-duration, rare target tone that occurred amongst frequent short-duration standard tones. There were a number of differences between unmedicated schizophrenics and controls in processing negativity elicited by standard tones. There was no evidence of hierarchical processing of stimulus dimensions in the early processing negativity component, and the late frontal component was virtually absent in schizophrenics. Furthermore, there was evidence that in schizophrenics the processing of the location dimension was delayed for standard tones having the same pitch as the target. The P300 component to attended target tones was substantially reduced in schizophrenics over parietal sites but there was no difference between the two groups over frontal sites. The results are interpreted in terms of multiple attentional deficits in schizophrenics that are indicative of a failure in the planning and execution of selective listening strategies. Such a failure may result from a dysfunction in the prefrontal regions of the brain.     

Untreated Hypertension Decreases Heritability of Cognition in Late Middle Age

Hypertension is a risk factor for cognitive decline, but the mechanisms underlying the effects of hypertension on cognition, particularly in midlife, are unclear. We examined whether hypertension modifies genetic influences on individual differences in cognition. Nine cognitive domains and general cognitive ability were assessed in a sample of 1,237 male twins aged 51–60 who were divided into three blood pressure groups: non-hypertensive; medicated hypertensive; and unmedicated hypertensive. Heritability was significantly lower among unmedicated hypertensives compared to medicated hypertensives and non-hypertensives for visual-spatial ability (p?=?0.013) and episodic memory (p?=?0.004). There were no heritability differences between non-hypertensives and medicated hypertensives. In addition, there were no significant differences in mean level cognition across the three blood pressure groups. These results suggest that in middle-aged men, untreated hypertension suppresses normal genetic influences on individual differences in certain domains of cognition prior to the emergence of hypertension-related effects on cognitive performance. These results further suggest that antihypertensive medication may protect against or reverse this effect.     

Altered balance in the autonomic nervous system in schizophrenic patients

The aim of the present study was to evaluate the autonomic nervous function in schizophrenic patients. Twenty-eight patients (29 +/- 6 years) diagnosed as schizophrenics and in stable medication were included, together with ten schizophrenic patients (25 +/- 5 years) who were unmedicated. Eleven healthy subjects (32 +/- 7 years) served as controls. Immediate heart-rate responses to a single deep inspiration was used as a measure of parasympathetic function. Heart-rate response to standing was used as a measure of sympathetic function. Supine blood pressure, heart-rate and orthostatic changes in blood pressure did not differ between groups. Heart-rate response to standing was greater in both medicated and non-medicated schizophrenics compared to normal subjects (P less than 0.01). Heart-rate response to standing was greater in non-medicated compared to medicated schizophrenics (P less than 0.05). Heart-rate response to inspiration was greater in non-medicated schizophrenics compared to normal subjects (P less than 0.05), whereas no difference was found between medicated and non-medicated schizophrenics. The results show that the balance in the autonomic nervous system is altered in schizophrenic patients with a hyperexcitability in both the sympathetic and the parasympathetic division. Our study has thus indicated a dysfunction in the autonomic nervous system per se and the previous interpretations of attentional orienting responses in schizophrenia is questioned. Medication with neuroleptics seems to partly normalize the autonomic reactivity rather than being the cause of autonomic dysfunction.     

Multiple measures of hemispheric dysfunction in schizophrenia and depression

Electrodermal, electroencephalographic and perceptual measures of lateral hemispheric function were obtained from groups of chronic schizophrenics, depressives and normals on 2 occasions, separated by 4 weeks. The measures of hemispheric function were derived from previous research. About half of the schizophrenics were medicated on both occasions; the other schizophrenics underwent drug 'washout' before the first session. Results revealed that the measures of laterality were not strongly intercorrelated. In the perceptual task, the schizophrenics and normals displayed different laterality effects. Unlike the normals, the schizophrenics' left hemisphere function appeared to be inferior to the right hemisphere function in the perceptual task. The laterality effects of the depressives and normals differed on two electrodermal measures: skin conductance level and skin conductance response amplitude. The depressives' electrodermal activity from the right hand was diminished as compared with the left hand; the normals did not show this effect. Medication decreased electrodermal activity in the schizophrenics, but had no significant effect on laterality. These results suggest that the various measures of laterality used singly in previous research in psychopathology may not all assess the same phenomenon.     

Lateralization patterns of event-related potential and performance indices in schizophrenia: relationship to clinical state and neuroleptic treatment

In a previous study we assessed lateralization patterns of verbal stimuli processing, by means of behavioural and neurophysiological measures, in a sample of drug-free schizophrenics and one of normal controls. The main findings obtained were the following: (1) a right visual field (RVF) advantage on reaction time (RT) and late positive complex (LPC) peak of the ERPs in normal subjects but not in schizophrenics; (2) a left visual field (LVF) significant advantage on P360 and slow wave (SW) amplitude in schizophrenics but not in controls; (3) a significantly longer RT and smaller P360 and SW for RVF stimuli in schizophrenics as compared to normals; (4) a significant contralateral effect of visual field on N180 at both the left and the right parietal site in normal controls and only at the right parietal site in schizophrenics. As a further step of this investigation we re-tested 9 schizophrenics after 28 days of haloperidol treatment. The post-treatment lateralization pattern of verbal stimuli processing was characterized by a RVF advantage on LPC peak amplitude and no visual field effect on P360 and SW, resembling the normal group pattern. Moreover, the N180 amplitude was found to be reduced. Relationships between lateralization pattern and clinical picture changes induced by haloperidol treatment are discussed.     

Monocular and binocular neuronal activity in human visual cortex revealed by electrical brain activity mapping

In the present study, we investigated topographical differences between monocularly and binocularly evoked potential fields related to the retinal location and spatial frequency of grating stimuli. Electrical brain activity was recorded in 18 healthy adults using an array of 21 electrodes over the occipital areas. Vertical black-and-white grating patterns of different spatial frequencies were presented with central fixation or lateralized to the left or right hemiretina. Computation of global field power determined component latency. Topographic characteristics of the field distributions were examined at the individual component latency for each subject using statistical comparisons between experimental conditions. The strength of the potential fields was significantly larger with binocular stimuli, whereas no effects were observed when comparing component latencies. Pronounced differences occurred in the spatial distribution of electrical brain activity: with 2.5 cycles/deg, large, significant topographic differences between monocularly and binocularly evoked activity were obtained. The potential fields showed a more anterior and more lateralized component distribution with binocular than monocular stimuli. In addition, when the gratings were presented binocularly, significant topographic differences were observed when low and high spatial frequency stimuli were compared. Our results suggest that the relationship between the topography of evoked components and retinal stimulus location and spatial frequency is different for monocular and binocular stimuli, indicating that binocular information processing triggers different neuronal processes in the human visual cortex.     

Interhemisphere differences during tasks involving attention and selection of lateralized stimuli

The state of cortical activation in the parietal and temporal areas of the right and left hemispheres was evaluated using evoked potentials (EP) during tasks consisting of selection of visual stimuli lateralized in the right and left visual fields and needing three different types of attention: to stimulus shape, to stimulus position, and simultaneously to stimulus shape and position. EP were recorded in 15 young healthy experimental subjects using six cortical leads: P3, P4, T3, T4, T5, and T6; the following endogenous EP components (in standard terminology) were analyzed: contingent negative variation (CNV), N1, P3, and the N1-P3 complex. Asymmetry in evoked potentials was assessed in terms of differences to contra-and ipsilateral stimuli in the right and left hemispheres. EP asymmetry was detected in the right hemisphere in all types of selection of lateralized stimuli. The magnitude of asymmetry in the right hemisphere depended on the level (or intensity) of attention: the degree of asymmetry increased with increases in the need for attention to analyze the stimuli. There was a significant relationship between the magnitude of asymmetry and the latent periods of the subjects’ responses. The functional significance of these data demonstrating asymmetry may be that it provides better spatial differentiation of visual signals in the right hemisphere, along with dominance of the right hemisphere in attention tasks. __________ Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 92, No. 6, pp. 709–722, June, 2006.     

Frequency tagging of steady‐state evoked potentials to explore the crossmodal links in spatial attention between vision and touch

The sustained periodic modulation of a stimulus induces an entrainment of cortical neurons responding to the stimulus, appearing as a steady‐state evoked potential (SS‐EP) in the EEG frequency spectrum. Here, we used frequency tagging of SS‐EPs to study the crossmodal links in spatial attention between touch and vision. We hypothesized that a visual stimulus approaching the left or right hand orients spatial attention toward the approached hand, and thereby enhances the processing of vibrotactile input originating from that hand. Twenty‐five subjects took part in the experiment: 16‐s trains of vibrotactile stimuli (4.2 and 7.2 Hz) were applied simultaneously to the left and right hand, concomitantly with a punctate visual stimulus blinking at 9.8 Hz. The visual stimulus was approached toward the left or right hand. The hands were either uncrossed (left and right hands to the left and right of the participant) or crossed (left and right hands to the right and left of the participant). The vibrotactile stimuli elicited two distinct SS‐EPs with scalp topographies compatible with activity in the contralateral primary somatosensory cortex. The visual stimulus elicited a third SS‐EP with a topography compatible with activity in visual areas. When the visual stimulus was over one of the hands, the amplitude of the vibrotactile SS‐EP elicited by stimulation of that hand was enhanced, regardless of whether the hands were uncrossed or crossed. This demonstrates a crossmodal effect of spatial attention between vision and touch, integrating proprioceptive and/or visual information to map the position of the limbs in external space.     

Lateralized cerebral dysfunction in schizophrenia and depression: gender and medication effects.

The neuropsychological functioning of 52 schizophrenic and 39 major depressive patients was examined using the four Luria-Nebraska Neuropsychological Battery lateralization scales, with the effects of gender and medication status examined alone and in interaction with diagnosis and laterality variables. Comparisons between the diagnostic groups revealed that gender influences some aspects of neuropsychological performance, particularly those involving bilateral complex cognitive-perceptual rather than sensorimotor skills. This effect was more distinct for depressives than schizophrenics when cerebral lateralization differences were present. There was no significant left hemisphere disadvantage for schizophrenics which was gender-related. Medication status revealed no appreciable effects for depressives, although both male and female schizophrenics receiving neuroleptics showed a greater degree of complex perceptual-cognitive dysfunction compared to unmedicated schizophrenics. Level of cerebral impairment was equivalent for the right and left hemispheres for both groups. Consequently, these data are not consistent with other findings demonstrating differential hemispheric disadvantages between schizophrenia and depression.     

Comparison of the effects of tibolone and estrogen replacement therapy on echocardiographic basic cardiac functions in post-menopausal women: a randomized placebo controlled study

Objectives: This study is designed to investigate and compare the effects of synthetic steroid tibolone and HRT on systolic and diastolic heart functions in post-menopausal women. Methods: This prospective, randomized placebo controlled double blind study was conducted in a university clinic. Fifty-eight non-smoking, otherwise healthy post-menopausal women who did not receive any kind of HRT at least for 3 years within the onset of menopause were included in the study. The patients were randomly allocated to either 2.5 mg per day tibolone (OD, n=18), daily combined 0.625 mg of conjugated estrogens 2.5 mg⁻¹ of medroxy progesterone acetate pill (EP, n=20) or a vitamin pill (n=20) in a double blinded fashion. Their basic systolic and diastolic functions were investigated with HP Sonos-1000 echocardiography using standard positions and windows before and 6 months after the initiation of HRT. Results: Mean age, weight, length of post-menopausal period, heart rate, systolic and diastolic pressures were similar between the groups. At the initiation of the study all groups had similar echocardiographic measurements. However, at the end of 6 months, left ventricular end-systolic and -diastolic volumes were decreased significantly compared to pretreatment and placebo in both EP and OD treated groups. (55.5±18.4 and 53.7±19.1.8 ml; 109.9±19.9 and 110.7±20.8 ml versus 74.5±14.9 and 142.7±19.1 ml, respectively; P<0.05). Improvement in diastolic functions was significant in EP/OD groups compared to pre-treatment period and the placebo groups (E/A 1.34±0.1 and 1.38±0.1 versus 1.18±0.09, deceleration time 204±11.1 and 202.8±27.1 ms versus 237.6±26.9 ms, respectively). Besides increase in left ventricular mass adjusted for height, decrease in left ventricular relative wall thickness, and systemic vascular resistance were significant in EP and OD treated groups than placebo and the pre-treatment measurements. Although improved in both OD and EP groups, the changes in systolic and diastolic functions were significantly higher in the OD treated group. Based on our preliminary results, we may conclude that both EP and OD regimens may improve cardiac performance and age related dysfunctions. Conclusion: The present results may further support that both OD and EP exert many direct effects on cardiovascular system other than metabolic changes regarding lipoproteins. The greater improvement in the OD group may be explained by its weak androgenic activity which is consistent with the in vitro data that androgens are potent relaxing agents on coronary arteries and restores cardiac myosin isoenzyme and ATPase patterns which mandates further clinical studies.     

Electrode Positioning for Reliable Telemetry ECG Recordings During Social Stress in Unrestrained Rats

We describe a surgical procedure for optimizing the location of telemetry ECG leads in rats. The new location was aimed at obtaining an accurate representation of ECG features throughout the cardiac cycle by limiting the voltage instability usually observed during intense somatomotor activity and improving the signal-to-noise ratio. The two electrodes (wire loops) were fixed on the dorsal surface of the xiphoid process and in the anterior mediastinum close to the right atrium. The implantation procedure was fast, little invasive, and allowed animals to completely recover from intervention. The performance of the “improved” location (IL, n = 10) with respect to two subcutaneous (SC) positionings (“conventional positioning,” CSP, n = 5; “updated location,” USL, n = 5) was evaluated by comparing ECGs obtained in baseline, stress and recovery conditions and during different behavioral activities (immobility and grooming). The resident-intruder test (emotional/physical challenge) was chosen as experimental stress paradigm. The noise level of ECGs obtained from IL rats was lower than in CSP and USL animals, in all recording conditions. Percentages of correctly recognized beats (CRBs) over the total number of beats (TBs) were significantly higher in IL rats than in CSP and USL animals, both in baseline conditions (99% vs. 11% and 40%) and situations involving high somatomotor activity (stress: 97%, 5% and 16%; recovery: 97%, 7%, and 15%) (p < 0.01). The performance of IL as compared to CSP and USL was also better when percentages during grooming and immobility were considered (grooming: 93% vs. 4% and 23%; immobility: 97%, 6%, and 33%; p < 0.01).     

An event-related potential study on the impairment of automatic processing of auditory input in schizophrenia

Summary Mismatch negativity (MMN) and P300 to auditory stimuli was carried out using global field power (GFP) in 25 schizophrenics and 25 normal controls. The peak latencies of MMN and P300 were significantly longer in schizophrenics than in normal controls, and the differences in MMN were marked in the frontal regions. The peak amplitudes of MMN and P300 were significantly smaller in schizophrenics. The scalp distribution of MMN to 1050 Hz tone differed between the two groups, although that to 1100 Hz was similar to each other. The results indicate an impairment in the automatic discrimination process of auditory input in schizophrenics.     

Brain Event-Related Potentials as Indicators of Early Selective Processes in Auditory Target Localization

To establish the stages of brain processing in an auditory stimulus localization task, event-related potentials (ERPs) were recorded from 24 normal subjects listening to brief white noise stimuli in a free-field situation from front, back, left and right loudspeakers. The subject's task was to respond to ‘target’ stimuli from one designated speaker. Performance varied as a function of sound location, stimuli in the front/back dimension being more difficult to localize than those in the left/right. ERP results, based on averaged waveforms, difference waveforms and the factors derived from a principal components analysis, revealed a series of task related components. Some were relatively transient, others more sustained in character. One brain component showed task related amplitude changes with an onset as early as 15 msec. These changes were target specific for sounds in the easier left/right dimension only. Later components, such as the P300, also varied in amplitude between targets and non-targets, but showed no significant amplitude or latency differences to target stimuli as a function of location, despite the significant performance differences.     

Evoked potential correlates of intelligence in nonpatient subjects

To evaluate possible influences of intelligence on evoked potential (EP) characteristics in nonpatients. EPs of age and gender matched groups (N = 19 each) of 'high', 'medium', and 'low' IQ groups were compared. EPs elicited by left and right median nerve stimulation, checkerboard pattern visual flash, and acoustic clicks were recorded from 15 scalp leads. The results confirmed previous findings showing that higher IQs are associated with higher EP amplitudes. An unexpected finding was a trend towards higher IQ/EP correlations for left than right recording sites. It appears that intelligence is an important subject variable to be controlled in any EP investigation, and furthermore that EP topography should be considered in seeking IQ/EP correlations.     

Trait anxiety impact on the EEG theta band power changes during appraisal of threatening and pleasant visual stimuli

The main objective of the present investigation was to examine whether trait anxiety construct would influence EEG event-related synchronization (ERS) of the theta power during viewing of visual threatening stimuli. The 62-channel EEG was recorded while low (LA, n=18) and high (HA, n=18) trait-anxious subjects viewed sequentially presented neutral, threatening and pleasant pictures. Between-group differences, related to stimulus emotionality, were linked to the test period of 0–1000 ms after stimulus onset. In the low theta (4–6 Hz) at prefrontal sites HA exhibited deficient ERS in response to both threatening and pleasant stimuli in the right hemisphere, whereas LA yielded larger right than left hemisphere ERS in response to all the three stimulus categories. In the upper theta (6–8 Hz) group differences were associated with posterior cortical regions: HA exhibited the largest ERS to threatening and the lowest to pleasant stimuli, whereas LA prompted the largest ERS to pleasant and the lowest to neutral pictures. It is suggested that low theta right prefrontal hypoactivation favoring left hemispheric (i.e. more analytical) activity along with higher upper theta ERS of posterior cortical regions (i.e. enhanced higher order visual processing) to threatening stimuli could form the basis for neuropsychologically observed general bias towards threatening information in HA.     

Projection onto Centroids Difference Vectors: A new approach to determine between group topographical differences,applied to P3 amplitude in Schizophrenia

Summary A common problem in electrophysiological research concerns between group analysis of EEG and ERP topography. This paper proposes a new technique for determining whether or not a significant difference exists between multiple scalp site measurements from two groups. The method requires noa priori assumptions about the data and is thus ideal for exploratory data analysis, and it also requires that only one statistical test need be performed (significantly reducing the possibility of type I errors). The Projection onto Centroids Difference Vectors (PCDV) method involves deriving a measure from each individual of whether their measurements across sites are closer overall to the mean measurements of the rest of their experimental group, or to the other group. These measures from each individual are then compared between groups using a Student'st test, which indicates whether one group's data is significantly spatially different from the other. In this study we describe the method in detail and apply it to both simulated data and to real auditory P3 data in unmedicated, medicated schizophrenics and matched normal controls. The PCDV method was also compared with statistical probability mapping (SPM). The PCDV method revealed the differences between the normal and patient groups more unambiguously than SPM, and the simulated data revealed that it was not liable to type I errors. PCDV provides an appropriate method for testing any between group EEG and ERP topographical differences.We wish to thank Mr. John Anderson, Research Officer in the Department of Psychiatry, Westmead Hospital, for his role in collecting the data which was analysed in this study, and Mr. Chris Rennie, Senior Scientific Officer in the Department of Medical Physics, for the development of the acquisition system used in this study.     

Lateralization patterns of verbal stimuli processing assessed by reaction time and event-related potentials in schizophrenic patients

Event-related potentials (ERPs), reaction time (RT), number of errors and number of omissions were recorded by using a visual target detection paradigm in which consonant pairs were presented in a central and in a lateral condition. Fourteen DSM III drug-free schizophrenics and 19 healthy subjects took part in the study. All of them were male and right-handed. Independent principal component analysis and varimax rotation were performed for each condition. Separate ANOVAs were performed on factor scores computed for each rotated principal component. In the central condition, schizophrenic patients showed a reduction of the late positive complex (LPC) peak with respect to normal controls, and this reduction was associated with a predominant negative symptomatology. No pattern of lateral asymmetry was found in either group for behavioural and ERP measures. For the lateral condition, a significant advantage of the right visual field (RVF) presentation (shorter RT and larger LPC peak for RVF stimuli) was observed in normal subjects, while no visual field effect on these two measures was detected in schizophrenics. Significant differences were found between the two groups on both behavioural and ERP measures for the RVF only. Furthermore, two ERP components showed a marked advantage of the left visual field in the patient group, associated with a predominance of positive symptoms in the clinical picture.     

92例恢复期女性精神分裂症患者述情障碍临床研究

目的探讨恢复期女性精神分裂症患者述情障碍及相关因素。方法应用多伦多述情障碍量表(TA S)对92例恢复期女性精神分裂症患者评定,并对不同文化程度、病程患者TA S评分进行比较。结果①恢复期女性精神分裂症患者TA S总均分及因子分均明显高于常模,差异具有显著性(t=3.04~10.56,均P<0.01);②不同文化程度患者的TA S总均分、因子Ⅰ、Ⅱ、Ⅳ分均存在显著差异性(t=1.98~8.06,P<0.05或P<0.01);③不同病程患者的TA S总均分、因子分存在显著差异(t=1.97~7.53,P<0.05或P<0.01)。结论恢复期女性精神分裂症患者存在着严重的述情障碍,文化程度低、病程长者述情障碍更严重。     

Anticoccodial protection and development of immunity to turkey coccidiosis while using monensin

Monensin at 60, 80 or 100 ppm provided sufficient early protection against coccidiosis in floor-pens seeded with a mixture of Eimeria adenoeides, E. gallopavonis and E. meleagrimitis oocysts to prevent mortality due to coccidiosis and permit satisfactory weight gains. Unmedicated poults suffered 7% mortality and significantly (P相似文献