Differences of latencies and amplitudes of brain stem evoked potentials in subgroups of a normal material

Brain stem auditory evoked potentials have been recorded in 40 normal subjects aged 13–48 years, by stimulating monaurally wiht random stimulus interval. The male subjects have latencies of the waves III-VII, which are significantly longer than female subjects ( P < 0.0005), the elongation increasing from 0.09 to 0.44 msec from wave III to VII. The female subjects have amplitudes significantly higher than male subjects, although the variations are very wide. No difference in latencies from tall versus short subjects is found, as well as no significant difference in latencies between subgroups of older and younger subjects of the material. It is found necessary to have different normal values for the two sexes.     

The effect of sex differences on event-related potentials in young adults.

Female/male cognitive differences have been studied for some time; however, such differences in Turkish population is unknown. Evoked potentials (EPs) of the brain have been applied as an index of information processing in a wide variety of normal and cognitive impaired subjects. Scalp event-related potentials (ERP) evoked by auditory stimuli were recorded in 20 male and 18 female neurologically and audiologically normal young Turkish subjects of 18-25 years (Av. 20.6) of age. Standard auditory "Oddball" paradigm involving simple discrimination task of concentrating on infrequent (target) stimulus and ignoring frequent (non-target) stimulus was employed. EEG activity was recorded at the Fz, Cz, Pz and Oz electrode sites of the 10-20 system using Ag/AgCl electrodes. Wave forms were collected and averaged off-line by a Pentium 100 computer, which also controlled the stimulus presentation. In general, significant main effects of gender and electrode site on evoked potential components were found. The interpeak amplitudes N1-P2 and N2-P3 were higher in the male subjects than in the female subjects at Cz. N2-P3 were higher in the male subjects than in the female subjects at Oz. The latencies of N1, P2, N2, P3 components were not different between both sex. For both sexes we found that N1-P2 amplitude was higher at Fz and Cz than Pz and Oz. N2-P3 amplitude was higher at Fz than Oz for only female subject. In male subjects, latency of N2 was longer at Fz than Oz. There were no significant differences in the latencies of N1, P2, and P3 components between electrode sites in both sexes. We suggest that ERP components could be affected by sex, electrode site, and cognitive performance.     

Auditory brain stem response (ABR) in eating disorder

Auditory brain stem responses were recorded in 10 eating disorder patients and 10 normal control subjects. Absolute latencies, interwave latencies, absolute amplitudes, and amplitude ratios were investigated. A nonsignificant difference was found between the eating disorder group and the normal control group as far as the absolute latencies and interwave latencies were concerned. But the eating disorder patients had significantly smaller amplitude ratios (III/I, IV-V/I) and absolute amplitude (V) than did the control subjects. These findings suggest that some dysfunction exists in the region of brain stem. It may be related with the pathophysiology in patients with eating disorder.     

Normative data for P1/N1-latencies of vestibular evoked myogenic potentials induced by air- or bone-conducted tone bursts.

OBJECTIVE: The response characteristics of acoustically elicited vestibular evoked myogenic potentials (VEMPs) largely depend on the stimuli applied. A tone-burst stimulation of 500 Hz seems to be clinically most appropriate because those VEMPs can be elicited at the lowest stimulus intensity possible. The aim of the present paper was to describe normative data for tone-burst evoked VEMPs. METHODS: VEMPs of 64 healthy subjects were recorded ipsilaterally during air- or bone-conducted tone burst stimulation. The EMG of the tonically activated sternocleidomastoid muscle was recorded ipsilaterally by surface electrodes. Averages were taken for P1/N1-latencies and -amplitudes of male and female volunteers within 3 different age groups. RESULTS: The latencies did not show any significant differences between female and male volunteers or between air- and bone-conducted stimulation. The latencies did also not show any significant difference among the 3 age groups. The limits for normal latencies (mean + 2 SD) are, therefore, 20.3 ms for P1 and 28.0 ms for N1. Although the P1/N1-amplitudes were decreased with increasing age, the tonic muscle activity was not significantly different between the age groups. CONCLUSIONS: The present findings strongly suggest the evaluation of VEMP latencies by using normative values obtained exactly with the same stimulus parameters. SIGNIFICANCE: Normative data as described in the present study are required to detect isolated saccular defects which are indicative of a vestibular disorder.     

Changes in the latencies of visual-evoked potentials in people undergoing tennis training——Dynamic comparison before and after 8 weeks training

BACKGROUND： Some previous studies have shown that exercise is an important factor that affects the latencies of visual-evoked potentials （VEPs）. OBJECTIVE： To investigate the effects of spending a period of time undergoing tennis training on the latencies of VEPs by comparing the latencies of VEPs before tennis training with those after 8 weeks of tennis training. DESIGN, TIME AND SETTING： The non-randomly concurrent controlled experiment was performed in the Department of Human Movement Sciences, Physical Education College, Shandong Normal University from April to June 2007. PARTICIPANTS： In total, 45 healthy volunteers from Shandong Normal University were selected as subjects, including 31 students majoring in physical education （11 males and 5 females participated in the tennis training plan for 8 weeks）, and 14 students from other subjects. Informed consent was obtained. According to whether they were majoring in physical education or not, and whether or not they took part in tennis training, the students were divided into 3 groups： a tennis group of physical education students （n = 16） a non-tennis group of physical education students （n =15） and a non-tennis group of non-physical education students （n = 14）. METHODS： The subjects in the tennis group took part in a regular tennis training plan of 2 hours a day and 3 days per week, for 8 weeks, while the subjects in two non-tennis groups were not in the tennis training plan The NDI-200 neural electricity tester （Shanghai Haishen Medical Electronic Instrument Co., Ltd.） was used to measure VEPs before and after the experiment in all three groups, and to compare the latencies of VEPs recorded before training with those recorded after training. MAIN OUTCOME MEASURES： Comparison of the changes in latencies of VEPs before and after 8 weeks of tennis training. RESULTS： All 45 subjects finished the test and datas from all were included in the statistical analysis. There were no significant differences among all the three group     

Platelet serotonin functions in untreated major depression

The uptake of [14C]5-HT, [3H]paroxetine and [3H]LSD binding was determined in platelets from 30 untreated patients with major depression and compared with corresponding variables from 30 healthy age-, sex- and season-matched control subjects. The maximum velocity (Vmax) for the 5-HT uptake was significantly decreased in patients (P = 0.014) compared to control subjects. Depressed women had significantly lower Vmax than female control subjects. In men, Vmax did not differ between patients and control subjects. Vmax was significantly lower in male inpatients compared with male outpatients (P = 0.05). The density (Bmax) of 5-HT uptake sites was found to be significantly increased in patients (P < 0.05) compared to control subjects and male patients had significantly higher Bmax than male control subjects, but there was no difference between female control subjects and female patients. No significant difference was found in Bmax of 5-HT2-receptors between patients and control subjects. A positive correlation was found between Bmax of 5-HT2-uptake sites and the degree of anxiety and between Bmax of 5-HT2 receptors and MADRS scores. Bmax of 5-HT2-receptors was positively correlated with the degree of suicidality. The results in the present study indicate that there may be a gender difference in serotonergic dysfunction in depression.     

The relationship of latency characteristics of the Hoffmann reflex from the right and left thenar muscles to serum testosterone levels in right-handed male and female subjects

The latency characteristics of the Hoffmann reflex from the right and left thenar muscles were analyzed in right-handed young men and women relative to serum testosterone levels. There was no correlation between the H-reflex latencies and serum testosterone levels in the female subjects. In the male subjects, the H-reflex latencies from the right and left sides were found to be negatively linearly related to the serum testosterone levels. The right minus left latencies were found to be inversely correlated with serum testosterone levels in women; there was no correlation between these variables in men. It was also established that the right-left differences in the H-reflex latencies were directly related to the degree of the right-hand preference in the female subjects. It was concluded that testosterone may, at least, contribute to the spinal-motor lateralization in women, but not in men. The results were also discussed with regard to the testosterone hypothesis of cerebral lateralization, sex-related differences, hand preference, hand skill, and intelligence.     

The interaction between sex and click polarity in brain-stem auditory potentials evoked from control subjects of Oriental and Caucasian origin

Brain-stem auditory evoked potentials (BAEPs) were performed on 30 male and 30 female young normal Oriental subjects, using both condensation and rarefaction stimulation. The effects of sex and click polarity on the BAEP latencies and amplitudes were studied. Females had shorter absolute and interpeak latencies and higher absolute amplitudes than the males. These sex-related BAEP differences were independent of the click polarity. Rarefaction clicks produced shorter wave I latency and longer I-III interpeak latency, but the differences were significant in the female only. The polarity-related BAEP amplitude differences were essentially independent of the sex. BAEPs performed on 60 sex- and age-matched young Caucasian subjects produced similar results. The importance of establishing control BAEP values according to the sex and click polarity is emphasised.     

5-HT(1A) receptor dysfunction in female patients with schizophrenia.

BACKGROUND: Serotonin (5-HT)(1A) receptors are of interest in the pathophysiology of schizophrenia (SCH) and the mechanism of action of atypical antipsychotic drugs. To test the hypothesis that 5-HT(1A) receptor responsivity is significantly different in patients with SCH compared to normal control subjects, the neuroendocrine study was performed using ipsapirone (IPS), a 5-HT(1A) partial agonist, as a probe. METHODS: Ipsapirone 0.5 mg/kg, p.o. or placebo were administered, in random order, to patients with SCH (n = 43; 32 male) and normal controls (n = 33; 21 male). Blood samples for plasma cortisol and body temperature were obtained from 30 min before to 180 min after administration of IPS or placebo. RESULTS: Female normal control subjects had markedly greater increases in plasma cortisol following IPS than did male control subjects. The placebo response-corrected plasma cortisol response to IPS was significantly blunted in female SCH compared to female normal control subjects (p =.0001). The IPS-stimulated plasma cortisol response in male SCH did not differ from that of male normal control subjects or female SCH. There were no significant differences in the IPS-induced hypothermia in men and women or between patients with SCH and normal control subjects. Behavioral responses to IPS, including nausea, dizziness, irritability, and feeling less well, did not differ between groups. CONCLUSIONS: These results suggest that the post-synaptic 5-HT(1A) receptor mediated endocrine response is diminished in female SCH compared to female normal control subjects, possibly secondary to an abnormality in intracellular signal transduction mechanism.     

Auditory Brain Stem Response (ABR) in Eating Disorder

Abstract: Auditory brain stem responses were recorded in 10 eating disorder patients and 10 normal control subjects. Absolute latencies, interwave latencies, absolute amplitudes, and amplitude ratios were investigated. A nonsignificant difference was found between the eating disorder group and the normal control group as far as the absolute latencies and interwave latencies were concerned. But the eating disorder patients had significantly smaller amplitude ratios (HI/I, IV-V/I) and absolute amplitude (V) than did the control subjects. These findings suggest that some dysfunction exists in the region of brain stem. It may be related with the pathophysiology in patients with eating disorder.     

Impulse conduction velocities in human biceps brachii muscles

Measurements of impulse conduction velocity were made in biceps brachii muscle fibers of male or female controls and of male body-builders. The technique involved exciting bundles of fibers with stimulating electrodes applied over the surface of the muscle, and recording compound action potentials with three small surface electrodes spaced 3 cm apart. By measuring latencies to the onsets and to the peaks of the negative deflections, it was possible to estimate conduction velocities in the fastest-conducting (FC) and intermediate-conducting (IC) fibers; the observed values ranged from 2.8 to 5.5 m·s⁻¹ in normal men and women. The mean conduction velocity for FC fibers was significantly higher in body-builders than in normal men and women; the mean IC value was significantly lower in women. In all three groups of subjects a decrease in conduction velocity could be demonstrated for FC fibers at the end of 1 min of maximal isometric contraction. In the body-builders, and probably in the other two groups of subjects, the FC fibers are considered to correspond to type II muscle fibers.     

There is a relatively left-biased grasp-reflex asymmetry in human newborns with familial sinistrality compared to those without familial sinistrality.

Grasp-reflex asymmetry was studied in human newborns with regard to familial sinistrality (FS). In the total sample, the following results were obtained. The mean grasp-reflex strength from the right hand was found to be significantly greater than that from the left hand in FS- subjects. There was no significant difference between these parameters in FS+ subjects. The mean right minus left (R-L) reflex strength was significantly greater than zero in FS- subjects. The mean R-L reflex did not significantly differ from zero in FS+ subjects. The mean reflex strength from the right hand was found to be significantly greater in FS- subjects than FS+ subjects. There was no significant difference between the mean reflex strengths from the left hands of the FS- and FS+ subjects. The mean R-L reflex in subjects FS- was found to be significantly greater than that in FS+ subjects. Similar results were obtained from the male and female subjects. It was concluded that FS is an important factor determining the degree of the grasp-reflex asymmetry in newborns. The relatively left-biased grasp-reflex asymmetry under the influence of FS indicates a genetic origin of the motor asymmetry in newborns. This, in turn, suggests that cerebral lateralization inducing manual asymmetry in humans may have been preprogrammed genetically.     

Sex differences in inferior parietal lobule volume in schizophrenia

OBJECTIVE: The inferior parietal lobule is a heteromodal association cortical region that has been implicated in the pathophysiology of schizophrenia. Inferior parietal lobule gray matter volumes have been shown to differ between healthy male and female subjects, with male subjects having larger left volumes. The authors sought to determine whether these volumetric sex differences also exist in patients with schizophrenia. METHOD: The authors used magnetic resonance imaging to measure inferior parietal lobule volumes of 15 pairs of male and female schizophrenic subjects who were individually matched to each other and to 15 pairs of healthy male and female subjects. RESULTS: Male schizophrenic patients exhibited a reversal of the normal left-greater-than-right male asymmetry in this region and had left inferior parietal lobule gray matter volumes that were significantly smaller than those of healthy male subjects. Female schizophrenic patients did not differ significantly from healthy female subjects in left or right inferior parietal lobule volume or in asymmetry. CONCLUSIONS: This study provides further evidence of brain morphology sex differences in schizophrenia that possibly contribute to the differential clinical disease expression in men and women.     

Are gender differences genetically related to catecholamine metabolism in schizophrenia?

Serum homovanillic acid (HVA) and norepinephrine (NE), serum dopamine-β-hydroxylase (DBH), platelet monoamine oxidase (MAO), and erythrocyte catechol-O-methyltransferase (COMT) have been measured in 86 healthy parents of schizophrenic patients and 36 normal control subjects. The t-test showed that serum HVA concentration was significantly higher in mothers of female patients than in mothers of male patients (p < .05); Kruskal-Wallis analysis revealed a significant difference in erythrocyte COMT activity among the mothers of male patients, mothers of female patients and female control subjects (H = 8.7, df = 2, p < .02); and the Mann-Whitney test demonstrated that erythrocyte COMT activity was significantly increased in mothers of male patients as compared with female control subjects (p < .01), but there were no significant differences in the HVA concentration and COMT activity between the fathers of male and female patients, and male control subjects. There were no significant changes in serum NE concentration, serum DBH and platelet MAO activity in these subjects. The present study suggests that catecholamine metabolism in mothers of schizophrenic patients may play a genetic role in the gender differences of schizophrenia.     

Areas of brain activation in males and females during viewing of erotic film excerpts

Various lines of evidence indicate that men generally experience greater sexual arousal (SA) to erotic stimuli than women. Yet, little is known regarding the neurobiological processes underlying such a gender difference. To investigate this issue, functional magnetic resonance imaging was used to compare the neural correlates of SA in 20 male and 20 female subjects. Brain activity was measured while male and female subjects were viewing erotic film excerpts. Results showed that the level of perceived SA was significantly higher in male than in female subjects. When compared to viewing emotionally neutral film excerpts, viewing erotic film excerpts was associated, for both genders, with bilateral blood oxygen level dependent (BOLD) signal increases in the anterior cingulate, medial prefrontal, orbitofrontal, insular, and occipitotemporal cortices, as well as in the amygdala and the ventral striatum. Only for the group of male subjects was there evidence of a significant activation of the thalamus and hypothalamus, a sexually dimorphic area of the brain known to play a pivotal role in physiological arousal and sexual behavior. When directly compared between genders, hypothalamic activation was found to be significantly greater in male subjects. Furthermore, for male subjects only, the magnitude of hypothalamic activation was positively correlated with reported levels of SA. These findings reveal the existence of similarities and dissimilarities in the way the brain of both genders responds to erotic stimuli. They further suggest that the greater SA generally experienced by men, when viewing erotica, may be related to the functional gender difference found here with respect to the hypothalamus.     

Relation of nonverbal intelligence assessed by Cattell's Culture Fair Intelligence Test to latencies of the somatosensory evoked potentials elicited by stimulation of the posterior tibial nerves in right-handed male and female subjects.

The association of nonverbal intelligence (NVI) with latencies of the somatosensory evoked potentials from the right and left posterior tibial nerves (PTNs) was studied in right-handed male and female subjects without familial sinistrality (FS-). There was a significant negative linear correlation between N49-P39 interpeak latencies from the right and left PTNs in females and a significant positive linear correlation between these parameters in males. There was no significant correlation between P58-N49 interpeak latencies and NVI in females, but a significant negative linear correlation in males. The N76-P58 interpeak latencies were found to be positively linearly related to NVI only in females; there was no correlation between these parameters in males. There was no significant correlation between IQ and side differences in SEP latencies in females. The right minus left P39 latencies from the right and left PTN were found to be negatively linearly related to IQ in males. In females with nearly equal heights, latencies of N49 waves were found to be negatively linearly related to IQ. In males with nearly equal heights, only P39 and P58 waves from the right PTN were found to be negatively linearly related to IQ. These results did not support the hypothesis of speed of information processing by the brain in behavioral intelligence. An asymmetrical organization of the male brain seems to be disadvantageous for nonverbal intelligence; the female brain appeared to be independent of the degree of asymmetrical organization of the brain in this respect.     

Vep latency: sex and head size.

OBJECTIVE: To investigate whether differences in visual evoked potential (VEP) latencies in a large sample of healthy subjects are influenced by different head size or sex or both. METHODS: Black-and-white pattern-reversal checkerboard VEPs at a frequency of 2c/deg. were recorded in a group of 54 normal subjects of both sexes (age 30.15+/-9.12 years). P100 latency was measured in all subjects and the data were analyzed in the whole sample and in a selected subgroup of subjects of both sexes with comparable head size. RESULTS: In the study group overall, the P100 latency was slightly shorter in females than males and this small difference reached only weak statistical significance (P<0.04) whereas head size differed significantly between sexes (females相似文献   

Clinical validation of antidromic stimulation of the ring finger in early electrodiagnosis of mild carpal tunnel syndrome.

Median and ulnar sensory distal latencies were measured antidromically on the fourth finger in 158 patients (224 hands) with suspected carpal tunnel syndrome (CTS), in 60 normal subjects (100 hands), and in 30 patients (30 hands) who suffered from paresthesiae due to a cervical spondylotic radiculopathy (CSR). The difference between these 2 latencies was less than 0.4 msec in all normals and patients with CSR, while in all of the patients with CTS it was more than 0.5 msec. Median sensory nerve conduction was significantly slower for the fourth than for the second finger in the CTS group, but not in controls. The difference between median and ulnar sensory distal latencies on the fourth finger proved to be the most sensitive of the tested parameters and was the only abnormal one in 20% of the clinically affected hands. The ring finger technique is a quick and easy procedure, which should be recommended in the early diagnosis of mild CTS.     

Effects of exercise on somatosensory-evoked potentials

The aim of this study was to investigate the effect of acute and regular exercise on somatosensory-evoked potentials (SEP). The study group was designed as 9 female and 7 male volleyball players, and the control group as 9 female and 7 male sedentary students. The P1 and P2 latency and amplitude values were measured by tibial nerve stimulation on both lower extremities in the study groups before and after exercise on a treadmill. Intra-group comparison was made to evaluate the acute effects of exercise, and inter-group comparison for the chronic effects of it. Statistically significant difference was determined in pre-exercise right P2 amplitudes and post-exercise left P2 latencies of female volleyball players and sedentary girls. There was significant difference between only the pre-exercise left P2 latency when comparison was made between the sportsmen and sedentary male subject groups. There were significant differences between the pre-exercise left P1 and P2 latency values of sportswomen and right P2 amplitudes of sedentary female subjects. There was no significant difference between left P2 latency values of sportsmen and sedentary male subjects. In conclusion, it was determined that acute and regular exercise shortened the latency of sensory-evoked potentials while decreasing their amplitudes. When evaluating the sensory-evoked potentials in electrophysiology laboratories, the exercise capacity and physical activity levels of the subjects should be considered.     

Short-latency somatosensory and brainstem auditory evoked potentials in patients with Parkinson's disease

Short-latency somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) were recorded in 44 patients with Parkinson's disease (mean age 67.3 years) and 23 normal subjects (mean age 69.3 years). Patients with Parkinson's disease and normal subjects did not show any significant difference with regard to the interpeak latencies between N13 and N20 central conduction time (CCTs). Likewise, there were no significant differences in CCTs between patients with and without dementia. The interpeak latencies between waves I and V (I-V IPLs) in patients with Parkinson's disease were significantly longer than those of the normal subjects (p less than 0.05). In particular, patients with dementia revealed significant prolongation of I-V IPLs compared to patients without dementia and normal subjects (p less than 0.01, p less than 0.001) although no significant differences were observed between patients without dementia and normal subjects. These results show that auditory brainstem pathways are involved in Parkinson's disease patients with dementia.