Search results for "Potentials"
showing 10 items of 1072 documents
Detrimental noise effects on brain's speech functions.
2009
Background noise has become part of our everyday life in modern societies. Its presence affects both the ability to concentrate and communicate. Some individuals, like children, the elderly, and non-native speakers have pronounced problems in noisy environments. Here we review evidence suggesting that background noise has both transient and Sustained detrimental effects on central speech processing. Studies on the effects of noise on neural processes have demonstrated hemispheric reorganization in speech processing in adult individuals during background noise. During noise, the well-known left hemisphere dominance in speech discrimination became right hemisphere preponderant. Furthermore, l…
Psychophysical and electrofunctional contrast sensitivity in cataractous patients treated with bendazac-lysine salt
1990
The clinical progression of the cataract may be influenced by drugs which reduce the denaturation of lens proteins. One of the most promising drugs is the bendazac-lysine salt. The drug was used in a double-blind study of a group of patients with initial cortical cataract in order to evaluate the changes in visual acuity and contrast sensitivity by means of a psychophysical and an electrophysiological method. After 6 months of treatment with bendazac the mean values of visual acuity showed a statistically significant increase in respect to baseline values, as well as an improvement of the threshold of contrast for most spatial frequencies. In the eyes treated with placebo there was no stati…
Brain event-related potentials (ERPs) measured at birth predict later language development in children with and without familial risk for dyslexia.
2005
We report associations between brain event-related potentials (ERPs) measured from newborns with and without familial risk for dyslexia and these same children's later language and verbal memory skills at 2.5, 3.5, and 5 years of age. ERPs to synthetic consonant-vowel syllables (/ba/, /da/, /ga/; presented equiprobably with 3,910-7,285 msec interstimulus intervals) were recorded from 26 newborns at risk for familial dyslexia and 23 control infants participating in the Jyvaskyla Longitudinal Study of Dyslexia. The correlation and regression analyses showed that the at-risk type of response pattern at birth (a slower shift in polarity from positivity to negativity in responses to /ga/ at 540-…
Deviance detection in sound frequency in simple and complex sounds in urethane-anesthetized rats
2019
Mismatch negativity (MMN), which is an electrophysiological response demonstrated in humans and animals, reflects memory-based deviance detection in a series of sounds. However, only a few studies on rodents have used control conditions that were sufficient in eliminating confounding factors that could also explain differential responses to deviant sounds. Furthermore, it is unclear if change detection occurs similarly for sinusoidal and complex sounds. In this study, we investigated frequency change detection in urethane-anesthetized rats by recording local-field potentials from the dura above the auditory cortex. We studied change detection in sinusoidal and complex sounds in a series of …
Intervention of two voltage-dependent calcium-entry pathways in the contractile response to acetylcholine and KCl in rat uterus.
1994
The contractile response of rat uterine smooth muscle was investigated. Verapamil and diltiazem concentration-dependently relax the sustained contractions induced by KCl (56 mmol/l) or acetylcholine (10(-4) mol/l). This inhibitory effect was not not freely reversed by washing the tissue and subsequently no contractile response was obtained in depolarized tissue, but a lower biphasic response (phasic and tonic) to acetylcholine was observed. Addition of cumulative concentrations of CaCl2 (1.2-19.2 mmol/l) induced a partial recovery of the contractile response to acetylcholine or KCl, but addition of MgCl2 (1.2-19.2 mmol/l did not. When the channel was reactivated by a third addition of KCl o…
Cl−uptake promoting depolarizing GABA actions in immature rat neocortical neurones is mediated by NKCC1
2004
GABA is the principal inhibitory neurotransmitter in the mature brain, but during early postnatal development the elevated [Cl−]i in immature neocortical neurones causes GABAA receptor activation to be depolarizing. The molecular mechanisms underlying this intracellular Cl− accumulation remain controversial. Therefore, the GABA reversal potential (EGABA) or [Cl−]i in early postnatal rat neocortical neurones was measured by the gramicidin-perforated patch-clamp method, and the relative expression levels of the cation−Cl− cotransporter mRNAs (in the same cells) were examined by semiquantitative single-cell multiplex RT-PCR to look for statistical correlations with [Cl−]i. The mRNA expression …
Vertigo and multiple sclerosis: aspects of differential diagnosis.
2002
Equilibrium disorders caused by involvement of brainstem and cerebellar structures are common in patients with multiple sclerosis (MS), but peripheral conditions such as benign paroxysmal positional vertigo (BPPV) can be sometimes confused with those of a central origin. Therefore, an accurate otoneurologic investigation paying attention to differential diagnosis aspects should be performed in these subjects. Among available diagnostic tools, electro-oculography, posturography and vestibular evoked myogenic potentials (VEMPs) are especially suited to assess vestibulo-oculomotor and vestibulospinal systems. This paper briefly describes the most recent otoneurologic diagnostic strategies for …
Study and modulation of human cortical excitability with transcranial magnetic stimulation.
1998
Transcranial magnetic stimulation (TMS) can be applied in different paradigms to obtain a measure of various aspects of cortical excitability. These different TMS paradigms provide information about different neurotransmitter systems, enhance our understanding about the pathophysiology of neuropsychiatric conditions, and in the future may be helpful as a guide for pharmacological interventions. In addition, repetitive TMS (rTMS) modulates cortical excitability beyond the duration of the rTMS trains themselves. Depending on rTMS parameters, a lasting inhibition or facilitation of cortical excitability can be induced. These effects can be demonstrated neurophysiologically or by combining rTMS…
Presence of muscarinic inhibitory and absence of nicotinic excitatory receptors at the terminal sympathetic nerves of chicken hearts.
1976
Nicotine (2 X 10(-4) M) or acetylcholine (5.5 X 10(-4) M) in the presence of 3 X 10(-6) M atropine did not increase the rate or amplitude of contraction in isolated atria or ventricular strips of the chicken heart; both drugs also did not cause an output of noradrenaline or adrenaline and did not evoke antidromic discharges in the right sympathetic nerves of isolated perfused chicken hearts. In contrast, "high K+-solutions" evoked an output of noradrenaline and adrenaline and caused a burst of antidromic discharges. Dimethylphenylpiperazine (DMPP; 3.1 X 10(-4) M), by a tyramine-like action, elicited a small output of noradrenaline and increased rate and amplitude of contraction" but did not…
Neurophysiological evaluation of visual function in iRBD: potential role in stratifying RBD conversion risk.
2021
Abstract Study objectives To evaluate neurophysiological alterations of visual function in idiopathic REM sleep Behavior Disorder (iRBD) both as markers and predictors of neurodegenerative disorders. Methods In a longitudinal follow-up study of 46 consecutive iRBD patients (follow-up duration 8.4 ± 3.4 years), the baseline parameters in luminance-contrast pattern (VEPp), red-green color (VEPc) and motion-onset (VEPm) Visual Evoked Potentials in iRBD were compared to early (ePD) and advanced (aPD) Parkinson's Disease subjects. Parameters of latency and amplitude of iRBD converters to neurodegenerative disease were compared with those of the non-converters. Results The VEP P100 mean latency v…