P50 variations in Behcet`s patients without neurologic findings.

Objective: In the present study, subclinical lesion involvement was investigated using the P50 component in Behcet`s patients without neurological manifestation.

Methods: We performed this clinical research in Erciyes University, Faculty of Medicine between December 2000 and November 2001. The studies were carried out on 18 Behcet`s patients without neurologic findings and 18 volunteers for control.

Effect of hyperglycemia on electrodermal activity in diabetic rats.

This study investigated the relationship between hyperglycemia and electrodermal activity (EDA) parameters in streptozotocin (STZ) induced diabetic rats. The article evaluates the course of development of neurophysiological alterations in the peripheral nervous system in diabetic rats through EDA. Rats were made diabetic using a moderate dose of STZ (DI) and high dose (DII).

Effect of PUVA therapy on electrodermal activity parameters in vitiligo patients.

Unlabelled: Recent electrophysiological studies on autonomic dysfunction in vitiligo patients show an autonomic dysfunction as measured by absent sympathetic skin response (SSR). Nothing is known about the reversibility of these autonomic parameters with treatment. The present study examined how Electrodermal Activity (EDA) parameters were affected from vitiligo illness before PUVA therapy and whether any electrophysiological gains acquired from PUVA therapy would influence the progression of the condition itself.

Sex-related differences in time estimation and the role of expectancy.

In this study, using auditory sequences, the authors designed an examination with three phases of stimulus-driven attention that is based on the possibility that involuntarily time shifts of attention are caused by nonunique stimulus properties. The purpose was to investigate whether attending and temporal expectancies are influenced by stimulus's properties and by sex. In each phase, an auditory stimulus train was presented, and the participant was asked to tap rhythmically in order to anticipate every fifth stimulus (or, in the third phase, the lack of it).

Utility of P300 auditory event related potential latency in detecting cognitive dysfunction in growth hormone (GH) deficient patients with Sheehan's syndrome and effects of GH replacement therapy.

Objective: Impaired cognitive function has been demonstrated in adults with growth hormone (GH) deficiency (GHD) by using different neuropsychological tests. Despite several studies, present knowledge about the impact of GHD and GH replacement therapy (GHRT) on cognitive function is limited. P300 event-related potential (ERP) application is a well-established neurophysiological approach in the assessment of cognitive functions including the updating of working memory content and the speed of stimulus evaluation.

Effects of cigarette smoking on cognitive processing.

Several previous studies have reported that cigarette smoking enhances performance of cognitive processing. These enhancements are generally attributed to the pharmacological effects of nicotine, while there is some debate whether the effects of smoking/nicotine are a result of recovery from abstinence. Evoked potentials (EPs) and event related potentials (ERPs) of the brain have been applied as an index of information processing in a wide variety of normal and cognitive impaired subjects.

The effect of immobilization stress on sensory gating in mice.

Central sensory filtering processes can be demonstrated using a paired stimulus paradigm. Normal humans show a diminished, vertex-recorded mid-latency (50 ms) of auditory evoked potential to the second of paired clicks (0.5 s apart), a phenomenon termed as auditory gating.

Effects of olanzapine on auditory P300 in schizophrenia.

Reduced auditory P300 amplitude generally has been considered to be a trait marker of schizophrenia, independent of antipsychotic treatment and clinical symptoms. However, several seemingly well-conducted studies have found P300 amplitude to be a state marker correlated with clinical symptoms. Recent research on atypical antipsychotics indicate that these medications may alter P300 amplitude as well as having beneficial clinical effects.

Evaluation of auditory evoked potentials from the inferior colliculus in rat.

This study aimed to investigate the usefulness of auditory evoked potentials (AEPs) in rats. To this end, N1, P2 latencies, and the N1-P2 amplitude of responses to different acoustic stimuli from rats, which were implanted with permanent electrodes in the inferior colliculus (IC), were evaluated and used to demonstrate the frequency characteristics of IC region. Permanent electrodes were implanted in IC regions of 7 male albino rats by the stereotaxic method.

A comparison of the different interpair intervals in the conditioning-testing P50 paradigms.

The conditioning-testing P50 paradigm is used to demonstrate sensory gating of responsiveness to auditory stimuli. Sensory gating is measured in terms of a suppression of the second (test) P50 component in that paradigm. The time course of sensory gating can be determined by examining subjects' gating of responsiveness to stimuli repeated at various interpair intervals.

Gamma response of the brain: a multifunctional oscillation that represents bottom-up with top-down processing.

This paper deals with the functional correlates of the gamma response of the brain. A critical review of the literature findings reveals the existence of two types of gamma responses: an early gamma that fulfills sensory functions and a late gamma that fulfills perceptual-cognitive functions. However, even the early gamma shows individual differences.

Habituation of the auditory evoked potential in a short interstimulus interval paradigm.

The present experiment was carried out to investigate elicitation and habituation of the auditory event related potentials with stimulus trains utilizing a short interstimulus intervals (ISI) of 1500 ms. Scalp event related potentials elicited by auditory stimuli were recorded in 10 male subjects. Thirty auditory stimuli were presented binaurally over headphones to every subject with a duration of 1000 ms, each with a constant ISI of 1500 ms.

The relation between event related potential and working memory in healthy subjects.

In numerous investigations the P300-component of the event related potential has proved a valid indicator of memory activities. The present study explores the amplitude and latency of the components of event-related potential regarding short-term memory task. Event related potentials, elicited by auditory stimuli, were recorded in 40 healthy subjects.

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.

Electrodermal activity in hypothyroid patients and healthy subjects.

The involvement of the central nervous system either in hypothyroidism or in hyperthyroidim has previously been shown on the basis of visual, auditory, somatosensory, and central motor evoked potential studies by some investigators. In to our previous study, we found that abnormal electrodermal activity in nonmedicated hyperthyroid patients was not associated with psychiatric symptoms. In this study, our purpose was to investigate whether hypothyroidism results in electrodermal abnormalities in the absence of measurable psychiatric symptoms.

Effect of reversed light-dark cycle on skin conductance in male rats.

Reversal of light-dark cycle was used to investigate the effect of the circadian changes on skin conductance, a tonic electrodermal activity parameter, in rats. Rats were adapted for 3 wk. to one of two lighting programs.

ELECTRODERMAL RESPONDING IN HYPERTHYROID PATIENTS.

The effects of hyperthyroidism on electrodermal habituation and responsiveness were examined in 43 hyperthyroid patients who were divided in two groups (medicated and unmedicated). In a comparison of 43 hyperthyroid and 43 normal controls; among patients with hyperthyroidism a great number of nonresponders were found. The distributions of SCR in habituation series in both group were almost the same but hyperthyroid patients were in slower habituation status than controls.

The relation between skin conductance level and plus-maze behavior in male mice.

The present study examined the correlation between anxiety scores and skin conductance level in 29 male Swiss Albino mice. Skin conductance (SC) was recorded with the SC unit and IBM-AT computer. Anxiety scores of mice were obtained from the elevated plus-maze test.

Zinc-induced alterations in contractile properties of rat diaphragm muscle in vitro.

The effect of zinc ions on the isometric contraction of rat diaphragm muscles in the presence and in the absence of external calcium was studied. Using a transducer, the isometric force was measured as a function of supramaximal electrical stimulation, either directly or indirectly applied to the muscle. The following parameters were measured: peak twitch tension, PT, twitch contraction time, CT, relaxation half-time, RT-1/2, and peak rates of tension increase and decrease, +dP/dt and -dP/dt.

Electrodermal activity in nonmedicated hyperthyroid patients having no depressive symptoms.

The aim of the present study was to investigate whether the alteration in hypothalamic-pituitary-thyroid axis function results in electrodermal abnormality without causing marked psychiatric manifestations or not. Electrodermal activity was recorded with the skin conductance unit and IBM-AT computer. Basal levels of electrodermal activity (EDA), as well as responsivity to repeated insignificant acoustic stimulation were studied in 24 nonmedicated hyperthyroid patients and 35 healthy controls.

Effects of grayanotoxin-I on threshold intensity and compound action potential of frog sciatic nerve.

Effects of (Grayanotoxin-I) GTX-I, one of the second group of sodium channel toxins, have been investigated on threshold stimulus voltage and upstroke velocity of isolated frog sciatic nerve. GTX-I was isolated from toxic honey obtained from the Black Sea Region of Turkey, and used in the experiments at the concentrations of 3.50(-5), 3.

Dependence of fatigue properties on the pattern of stimulation in the rat diaphragm muscle.

Diaphragm fatigue was studied in isolated phrenic nerve diaphragm strips from 28 Swiss Albino rats. Three procedures were used to estimate the isometric twitch characters and force frequency responses to fatigue of the rat diaphragm at different rates of phrenic nerve stimulation. Diaphragm fatigue was induced by using low frequency stimulation (0.

Rat diaphragm muscle contraction with and without oxygen enrichment.

We investigated the effect of deprivation of oxygen circulation in the organ bath on the tension generation of the diaphragm in vitro. Adult male Swiss Albino rats were quickly killed and the left hemidiaphragms removed. Isolated phrenic nerve-diaphragmatic strip preparations were placed in an individual organ chamber containing Krebs solution and were connected to a force displacement transducer.

The effects of theophylline and caffeine on the isolated rat diaphragm.

It is a well known fact that theophylline enhances the force of diaphragmatic contraction and delays fatigue. The action of caffeine which is a methylxanthine analogue on skeletal muscle are complex. It was claimed in few studies that the caffeine was more effective on the diaphragmatic contractility than the theophylline.

Effects of honey containing grayanotoxin I on frog gastrocnemius muscle.

The presence of grayanotoxins (GTX-I, GTX-II and GTX-III) in honey samples from the Mediterranean Sea and Black Sea regions of Turkey and the effect of honey containing GTX-I on the threshold stimulus voltage of frog gastrocnemius muscle were studied. We used 2 groups of gastrocnemius muscles isolated from curarized or noncurarized frogs. The threshold voltage was measured by external perfusion with a polygraphic system.