Search results for "evoked potential"
showing 10 items of 604 documents
Auditory event-related potentials in subcortical vascular cognitive impairment and in Alzheimer's disease.
2006
Few studies exist on ERPs and patients with subcortical vascular cognitive impairment (SVCI). This latter is a quite homogeneous subtype of vascular dementia whose cognitive profile is quite different from that of Alzheimer disease (AD).The present study aims at comparing the ERPs profile both in patients with SVCI and in patients with AD.ERPs and psychometric tests were collected from 39 healthy elderly controls, 51 patients with SVCI and 43 patients with AD. Subjects mentally count high pitched target tones that were randomly intermixed with low pitched frequent tones. We measured ERPs latencies (N1, P2, N2 and P3), and interpeak latencies (N1-P3, N1-P2, N1-N2).Grand averaged potentials i…
Auditory event-related potentials at preschool age in children born very preterm.
2014
Abstract Objective To assess auditory event-related potentials at preschool age in children born very preterm (VP, 27.4±1.9 gestational weeks, n =70) with a high risk of cognitive dysfunction. Methods We used an oddball paradigm consisting of a standard tone randomly replaced by one of three infrequent deviants (differing in frequency, sound direction or duration). Results The P1 and N2 latencies were inversely correlated to age (50–63months) both in VP ( r =−0.451, p r =−0.305, p= 0.01, respectively) and term born controls (TC; n =15). VP children had smaller P1 than near-term ( n =12) or TC (1.70±0.17μV vs 2.68±0.41 and 2.92±0.43, respectively; p Conclusions Our data suggest a fast matura…
Habituation or lack of habituation: What is really lacking in migraine?
2015
Migraine is very prevalent disease with consistent disability and socioeconomic burden (Lipton et al., 2007). Despite intensive research effort, particularly in last decades, allowing significant insight in many aspects of the disease, its precise pathophysiological bases remain still to be defined. One influential view suggests that dysfunctions in sensory information processing could play a critical role (de Tommaso et al., 2014). In this frame a relevant phenomenological marker is considered the inability of migraine patients to habituate to repeated sensory stimulation.
Considerable deficits in the detection performance of the cat after lesion of the suprasylvian visual cortex
1989
The ability of two cats to discriminate between two geometrical outline patterns in the presence of superimposed structured background was tested before and after bilateral removal of the lateral suprasylvian visual areas (PMLS, PLLS, AMLS, ALLS, part of area 7). There were mild deficits when patterns and background were kept stationary; these deficits may be due to a partial undercutting of areas 17, 18 and 19. However, there was a severe impairment in performance when the patterns were moving on a stationary background which may be due to loss of the suprasylvian visual areas. Movement of the background relative to the figure resulted in an intermediate detection deficit.
Central Contribution to Electrically Induced Fatigue depends on Stimulation Frequency
2017
International audience; PURPOSE: This study analyzed the impact of several protocols of neuromuscular electrical stimulation (NMES), matched with a similar total torque-time integral, on muscle activation pathways and neuromuscular fatigue.METHODS: Ten young healthy participants (age: 24.6 +/- 4.2) performed 3 randomized NMES sessions on the triceps surae muscles with 20 Hz, 60 Hz or 100 Hz stimulation frequencies (pulse duration: 1 ms), with pulse amplitude (IES) set at 20 % of isometric maximal voluntary contraction (MVC). Muscle activity during NMES was assessed by means of the twitch, the soleus H-reflex and M wave responses evoked by single muscle stimulation at IES. Neuromuscular fati…
Impaired neuromuscular transmission during partial inhibition of acetycholinest-erase: The of stimulus-induced antiromic backfiring in the generation…
1992
Neuromuscular transmission was studied in the rat phrenic nerve-hemidiaphragm preparation with acetylcholinesterase (AChE) partially inactivated. Enzyme inhibition resulted in (1) increased single-twitch tension of the diaphragm; (2) compound muscle action potential (CMAP) containing repetitive discharges; (3) stimulus-induced antidromic backfiring (SIAB) seen in the phrenic nerve; and (4) repetitive nerve stimulation (RNS) eliciting a decrement-increment (D-I) phenomenon (i.e., amplitude reduction maximal with the second CMAP). Using a high-calcium and low-magnesium solution, SIAB and the decrement of the second CMAP during RNS were intensified, whereas closely spaced trains and (+)-tubocu…
Does mismatch negativity show differences in reading-disabled children compared to normal children and children with attention deficit?
2007
An auditory event-related potential (ERP) component called mismatch negativity (MMN) was examined in three groups of children (n = 63) aged 8-14 years. A control group comprised healthy children in second or sixth grade of comprehensive school (n = 21). The two clinical groups included children with reading disability (RD) (n = 21) and children with attention deficit (AD) (n = 21). MMN was elicited in a passive oddball paradigm by duration changes in a continuous sound, consisting of two alternating (600 and 800 Hz) 100 msec tones. The deviant tones were either 30 or 50 msec in duration. Both deviants elicited a clear MMN in all groups. Statistical analyses showed no systematic difference i…
Mismatch negativity (MMN) elicited by duration deviations in children with reading disorder, attention deficit or both.
2007
According to several studies auditory discrimination as measured by mismatch negativity (MMN) is compromised in participants with reading disorder. However, studies on duration discrimination have produced conflicting findings [Baldeweg, T., Richardson, A., Watkins, S., Foale, C., & Gruzelier, J., 1999. Impaired auditory frequency discrimination in dyslexia detected with mismatch evoked potentials. Annals of Neurology, 4, 1-9; Corbera, S., Escera, C., & Artigas, J., 2006. Impaired duration mismatch negativity in developmental dyslexia. Neuroreport, 17, 1051-1055]. Auditory sensitivity has not been as actively investigated among children with attention deficit, although attention problems of…
Visual evoked potentials in insulin-dependent diabetics
1985
The latency of pattern-reversal VEPs was studied in type I insulin-dependent diabetics without retinal and extraocular involvement. One hundred eyes of 50 diabetics (mean age 19.8 +/- 7.2 years) formed the study group; the duration of the disease ranged between 1 month and 15 years. The latencies of VEPs were progressively delayed in relation to the duration of the disease, becoming more and more evident and stabilizing after about 6 years from the onset of diabetes. The VEP alterations probably indicate alteration of membrane balance or demyelinization.
Time course of ERP generators to syllables in infants: A source localization study using age-appropriate brain templates
2011
article i nfo Event-related potentials (ERPs) have become an important tool in the quest to understand how infants pro- cess perceptual information. Identification of the activation loci of the ERP generators is a technique that pro- vides an opportunity to explore the neural substrates that underlie auditory processing. Nevertheless, as infant brain templates from healthy, non-clinical samples have not been available, the majority of source localization studies in infants have used non-realistic head models, or brain templates derived from older children or adults. Given the dramatic structural changes seen across infancy, all of which profoundly affect the electrical fields measured with …