Search results for "HALO"
showing 10 items of 2623 documents
Contrast sensitivity and glare disability by halogen light after monofocal and multifocal lens implantation
2000
BACKGROUND—Standard examination of contrast sensitivity under conditions of glare disability is performed with incandescent light. A new halogen glare test that simulates glare as seen with oncoming vehicle headlights was used to measure glare disability in patients implanted with multifocal and monofocal intraocular lenses (IOLs). METHODS—28 patients with an average age of 69 years (SD 12 years) were implanted with a monofocal IOL (SI-40NB, Allergan) and 28 patients with an average of 66 years (12 years) were implanted with a refractive multifocal IOL (Array-SA-40N, Allergan). All patients were followed for 5 months postoperatively. Contrast sensitivity at four spatial frequencies (3, 6, 1…
The development of involuntary and voluntary attention from childhood to adulthood: A combined behavioral and event-related potential study
2006
Abstract Objective This study investigated auditory involuntary and voluntary attention in children aged 6–8, 10–12 and young adults. The strength of distracting stimuli (20% and 5% pitch changes) and the amount of allocation of attention were varied. Methods In an auditory distraction paradigm event-related potentials (ERPs) and behavioral data were measured from subjects either performing a sound duration discrimination task or watching a silent video. Results Pitch changed sounds caused prolonged reaction times and decreased hit rates in all age groups. Larger distractors (20%) caused stronger distraction in children, but not in adults. The amplitudes of mismatch negativity (MMN), P3a, a…
Time course of human 40 Hz EEG activity accompanying P3 responses in an auditory oddball paradigm
1997
In order to quantify the time course of auditory P3-related gamma activity, root mean square (RMS) values were calculated from band-filtered (30-45 Hz) target and non-target responses in an auditory oddball experiment. Evoked (phase locked) gamma activity was evaluated from the time domain averages, whereas induced (not necessarily phase locked) activity was analyzed on the basis of single trials. Gamma RMS values were integrated across different time windows, namely the prestimulus, N50/P50, N100, pre P3, P3 and post P3 window. The single trial P3 window hereby was defined by a maximum amplitude criterion. In accordance with other studies, we found a pronounced increase of evoked gamma act…
Dysfunctional cortical inhibition in adult ADHD: neural correlates in auditory event-related potentials.
2013
In recent times, the relevance of an accurate diagnosis of attention-deficit/hyperactivity disorder (ADHD) in adults has been the focus of several studies. No longer considered a pathology exclusive to children and adolescents, and taking into account its social implications, developing enhanced support tools for the current diagnostic procedure becomes a priority. Here we present a method for the objective assessment of ADHD in adults using chirp-evoked, paired auditory late responses (ALRs) combined with a two-dimensional ALR denoising scheme to extract correlates of intracortical inhibition. Our method allows for an effective single-sweep denoising, thus requiring less trials to obtain r…
Auditory event-related potentials over medial frontal electrodes express both negative and positive prediction errors
2015
International audience; While the neuronal activation in the medial frontal cortex is thought to reflect higher-order evaluation processes of reward prediction errors when a reward deviates from our expectation, there is increasing evidence that the medial frontal activity might express prediction errors in general. However, given that several studies examined the medial frontal event-related potentials (ERPs) by comparing signals triggered by different stimuli and different anticipations, it remains an open question whether the medial frontal signals are sensitive to the valence of prediction errors. Here we orthogonally manipulated expectation magnitude (i.e., large/small expectation) and…
Effects of Selective Attention on Syntax Processing in Music and Language
2010
Abstract The present study investigated the effects of auditory selective attention on the processing of syntactic information in music and speech using event-related potentials. Spoken sentences or musical chord sequences were either presented in isolation, or simultaneously. When presented simultaneously, participants had to focus their attention either on speech, or on music. Final words of sentences and final harmonies of chord sequences were syntactically either correct or incorrect. Irregular chords elicited an early right anterior negativity (ERAN), whose amplitude was decreased when music was simultaneously presented with speech, compared to when only music was presented. However, t…
The auditory N1 suppression rebounds as prediction persists over time
2016
International audience; The predictive coding model of perception proposes that neuronal responses reflect prediction errors. Repeated as well as predicted stimuli trigger suppressed neuronal responses because they are associated with reduced prediction errors. However, many predictable events in our environment are not isolated but sequential, yet there is little empirical evidence documenting how suppressed neuronal responses reflecting reduced prediction errors change in the course of a predictable sequence of events. Here we conceived an auditory electroencephalography (EEG) experiment where prediction persists over series of four tones to allow for the delineation of the dynamics of th…
Processing of auditory stimuli during tonic and phasic periods of REM sleep as revealed by event-related brain potentials
1996
The brain has been reported to be more preoccupied with dreams during phasic than during tonic REM sleep. Whether these periods also differ in terms of the processing of external stimuli was examined. Event-related brain potentials (ERPs) to a frequent standard tone of 1000 Hz (P = 97%) and infrequent deviant tones of 1100 and 2000 Hz (P = 1.5% for each) were recorded (n = 13) during wakefulness and nocturnal sleep. An ERP wave (called REM-P3) resembling a waking P3 wave was larger for the 2000 Hz deviant during tonic than during phasic REM sleep. Also the P210 wave was larger during tonic than during phasic REM sleep. A reliable mismatch negativity component appeared only in wakefulness. I…
Speech- and sound-segmentation in dyslexia: evidence for a multiple-level cortical impairment
2006
Developmental dyslexia involves deficits in the visual and auditory domains, but is primarily characterized by an inability to translate the written linguistic code to the sound structure. Recent research has shown that auditory dysfunctions in dyslexia might originate from impairments in early pre-attentive processes, which affect behavioral discrimination. Previous studies have shown that whereas dyslexic individuals are deficient in discriminating sound distinctions involving consonants or simple pitch changes, discrimination of other sound aspects, such as tone duration, is intact. We hypothesized that such contrasts that can be discriminated by dyslexic individuals when heard in isolat…
Learning-induced neural plasticity of speech processing before birth
2013
Learning, the foundation of adaptive and intelligent behavior, is based on plastic changes in neural assemblies, reflected by the modulation of electric brain responses. In infancy, auditory learning implicates the formation and strengthening of neural long-term memory traces, improving discrimination skills, in particular those forming the prerequisites for speech perception and understanding. Although previous behavioral observations show that newborns react differentially to unfamiliar sounds vs. familiar sound material that they were exposed to as fetuses, the neural basis of fetal learning has not thus far been investigated. Here we demonstrate direct neural correlates of human fetal l…