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Auditory Evoked Potentials (auditory + evoked_potential)
Kinds of Auditory Evoked Potentials Selected AbstractsEnhancement of steady-state auditory evoked magnetic fields in tinnitusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2004Eugen Diesch Abstract The steady-state auditory evoked magnetic field and the Pbm, the magnetic counterpart of the second frontocentrally positive middle latency component of the transitory auditory evoked potential, were measured in ten tinnitus patients using a 122-channel gradiometer system. The patients had varying degrees of hearing loss. In all patients, the tinnitus frequency was located above the frequency of the audiometric edge, i.e. the location on the frequency axis above which hearing loss increases more rapidly. Stimuli were amplitude-modulated sinusoids with carrier frequencies at the tinnitus frequency, the audiometric edge, two frequencies below the audiometric edge, and two frequencies between the audiometric edge and the tinnitus frequency. Below the audiometric edge, the root-mean-square field amplitude of the steady-state response computed across the whole head as well as the contralateral and the ipsilateral dipole moment decreased as a function of carrier frequency. With carrier frequency above the audiometric edge, the steady-state response increased again. The amplitudes of the transitory Pbm component were patterned in a qualitatively similar way, but without the differences being significant. For the steady-state response, both whole-head root-mean-square field amplitude and the dipole moment of the sources at the tinnitus frequency showed significant positive correlations with subjective ratings of tinnitus intensity and intrusiveness. These correlations remained significant when the influence of hearing loss was partialled out. The observed steady-state response amplitude pattern likely reflects an enhanced state of excitability of the frequency region in primary auditory cortex above the audiometric edge. The relationship of tinnitus to auditory cortex hyperexcitability and its independence of hearing loss is discussed with reference to loss of surround inhibition in and map reorganization of primary auditory cortex. [source] Prenatal Antecedents of Newborn Neurological MaturationCHILD DEVELOPMENT, Issue 1 2010Janet A. DiPietro Fetal neurobehavioral development was modeled longitudinally using data collected at weekly intervals from 24 to 38 weeks gestation in a sample of 112 healthy pregnancies. Predictive associations between 3 measures of fetal neurobehavioral functioning and their developmental trajectories to neurological maturation in the first weeks after birth were examined. Prenatal measures included fetal heart rate (FHR) variability, fetal movement, and coupling between fetal motor activity and heart rate patterning; neonatal outcomes include a standard neurologic examination (n = 97) and brainstem auditory evoked potential (BAEP; n = 47). Optimality in newborn motor activity and reflexes was predicted by fetal motor activity, FHR variability, and somatic,cardiac coupling predicted BAEP parameters. Maternal pregnancy-specific psychological stress was associated with accelerated neurologic maturation. [source] Undulating toe movements in brain death,EUROPEAN JOURNAL OF NEUROLOGY, Issue 11 2004G. Saposnik For many years, death implied immobility. Nevertheless, there are anecdotal reports of spontaneous or reflex movements (SRMs) in patients with Brain death (BD). The presence of some movements can preclude the diagnosis of BD, and consequently, the possibility of organ donation for transplantation. McNair and Meador [(1992), Mov Dord7: 345,347] described the presence of undulating toe flexion movements (UTF) in BD patients. UTF consists in a sequential brief plantar flexion of the toes. Our aim was to determine the frequency, characteristics and predisposing factors of UTF movements in a prospective multicenter cohort study of patients with BD. Patients with confirmed diagnosis of BD were assessed to evaluate the presence of UTF using a standardized protocol. All patients had a routine laboratory evaluation, CT scan of the head, and EEG. Demographic, clinical, hemodynamic and blood gas concentration factors were analyzed. amongst 107 BD patients who fulfilled the AAN requirements, 47 patients (44%) had abnormal movements. UTF was observed in 25 (23%) being the most common movement (53%). Early evaluation (OR 4.3, CI95% 1.5,11.9) was a predictor of UTF in a multivariate regression model. The somato-sensory evoked potential (SSEPs) as well as brainstem auditory evoked potentials (BAEPs) did not elicit a cortical response in studied patients with UTF. This spinal reflex is probably integrated in the L5 and S1 segments of the spinal cord. Abnormal movements are common in BD, being present in more than 40% of individuals. UTF was the most common spinal reflex. In our sample, early evaluation was a predictor of UTF. Health care professionals, especially those involved in organ procurement for transplantation, must be aware of this sign. The presence of this motor phenomenon does not preclude the diagnosis of BD. [source] Central effects of botulinum toxin: study of brainstem auditory evoked potentialsEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2000P. Ce No abstract is available for this article. [source] Loudness dependence of evoked dipole source activity during acute serotonin challenge in femalesHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 1 2008Christine Norra Abstract Objectives Direct challenge of cortical serotonergic (5-hydroxytryptamine, 5-HT) availability by tryptophan depletion test (TDT) was used to assess the hypothesized inverse relationship between central 5-HT function and loudness dependence of auditory evoked potentials (LDAEPs). Gender must be taken into particular account here, since there are gender differences in 5-HT brain synthesis, with women reacting more strongly to TDT. Methods In a double-blind, controlled cross-over study, 16 healthy females were ingested two highly concentrated amino acid mixtures with (+TRP) or without TRP (,TRP). While monitoring TRP levels and mood states, the AEP of different loudness stimuli were recorded, followed by dipole source analysis. Results Under the ,TRP condition, free plasma TRP levels decreased by 81.10% (±5.14). Most of the loudness change rates of the relevant N1/P2 tangential dipole activities were significantly increased under ,TRP, but calculated LDAEP did not differ significantly between treatments. LDAEP and states of mood were not correlated. Conclusions Despite strong TRP depletion, the results did not reach sufficient evidence that LDAEP is a valid biological marker of central 5-HT activity in females when using TDT. This agrees with the literature and supports the view that LDAEP indicates predominantly biological vulnerability in predisposed individuals. Copyright © 2007 John Wiley & Sons, Ltd. [source] Linear and whorled nevoid hypermelanosis associated with developmental delay and generalized convulsionsINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2 2004Ahmad A. Alrobaee MD A 2-year-old Saudi boy was seen in our dermatology clinic with symmetrical, brown, linear macules over the legs, trunk, and arms (Figs 1,3). He was a product of a full-term vaginal delivery following an uneventful first pregnancy in a 22-year-old mother. The birth weight was 2.3 kg. The hyperpigmented macules followed the lines of Blaschko and were noticed a few months after birth; they had enlarged with body growth until the age of 18 months. There was no family history of a similar condition and the boy's parents were unrelated. No blistering or inflammatory changes preceded the hyperpigmentation. The palms, soles, nails, scalp, mucous membranes, and teeth were normal. In addition to the hyperpigmented macules, the patient started to have generalized convulsions at the age of 2 months. Figure 1. Linear hyperpigmented macules following the lines of Blaschko Figure 2. Close up view of the hyperpigmented macules Figure 3. Trunk: Hyperpigmented macules in whorled distribution Physical examination revealed delayed developmental milestones, microphthalmia, depressed nose, and high arched palate with no other abnormalities. Blood tests were normal. Magnetic resonance imaging of the brain showed changes suggestive of a demyelinating process at the parieto-occipital white matter. Echocardiography revealed an atrial septal defect. Electroretinography (ERG), visual evoked potentials (VEP), and auditory evoked potentials (AEP) were normal. Electroencephalogram (EEG) showed multifocal epileptic discharge in the posterior region. A punch skin biopsy taken from the hyperpigmented lesions showed an increase in the melanin content of the basal layer with no incontinence of pigment or melanophages in the dermis. [source] Visual and brainstem auditory evoked potentials in children with headachePEDIATRICS INTERNATIONAL, Issue 5 2008Bulent Unay Abstract Background: Headache is a common problem in the pediatric population. The purpose of the present study was to evaluate visual evoked potentials (VEP) and brainstem auditory evoked potentials (BAEP) in children with headache. Methods: Thirty-seven children fulfilling the International Headache Society Criteria for a diagnosis of migraine, 35 children with tension-type headache and 40 healthy children (control group) were enrolled in the study. Results: The mean age of patients and controls was 10.4 years. P100 latency and amplitudes of migraine patients were significantly higher than children with tension-type headache and control subjects. Children with tension-type headache also had higher P100 latency and amplitude values than control subjects but there was no statistical difference. BAEP responses were similar between all groups. Conclusion: Measurement of VEP latency and amplitude is a valuable and reliable test for the diagnosis of migraine and can be used safely in childhood. [source] Etiologic yield of autistic spectrum disorders: A prospective studyAMERICAN JOURNAL OF MEDICAL GENETICS, Issue 1 2006Agatino Battaglia Abstract Studies addressing etiologic yield in childhood developmental disabilities have mainly looked at individuals with developmental delay/mental retardation. The few studies addressing the question of etiologic yield in patients with pervasive developmental disorders (PDDs) had a major drawback, in that the enrolled subjects were diagnosed as having the autistic spectrum disorders based only on history and clinical examination, and/or on unspecified instruments. In addition, only some of these patients underwent a complete laboratory evaluation. To investigate the etiologic yield of PDDs, we undertook a large prospective study on subjects selected according to very strict criteria and diagnosed as having PDD based on the present "gold standard" (ADI-R and ADOS-G), and a clinical diagnosis made by a child psychiatrist. Eighty-five (85) patients with PDD and their first degree relatives participated in this study. These patients were selected from a sample of 236 subjects who had received a clinical diagnosis of PDD at the Stella Maris Institute between March 2002 and 2005. Selection criteria for entering the study were: (1) a diagnosis of PDD (with exclusion of the Rett syndrome) confirmed after the administration of the ADI-R (autism diagnostic interview-revised) and the ADOS-G (autism diagnostic observation schedule-generic). In addition, a clinical diagnosis was made by the child psychiatrist, on the basis of presence or absence of DSM-IV symptoms of autism; (2) chronological age between 4 and 18 years; (3) IQ>30; (4) availability of both biologic parents. Patients, 65/85 (76.5%), had autism, 18/85 (21.2%) had PDD-NOS, and the remaining 2/85 (2.3%) had Asperger syndrome. Ages varied between 4 years 2 months and 12 years 5 months (mean 7.6 years), and there was a marked male preponderance (68/85). All subjects underwent various laboratory studies and neuroimaging. With respect to possible etiologic determination, a detailed history and physical examination in this group of patients with PDD was informative in 10.5% (9/85). HRB karyotype was diagnostic in one, and molecular fragile X studies in one child. Brain MRI was informative in two children (2.3%) with relative macrocrania but no neurological features; and EEG was helpful in one child, identifying a Landau,Kleffner disorder. Audiometry and brainstem auditory evoked potentials (BAEPs) showed a bilateral sensorineural loss in another child. Metabolic evaluation gave normal results in all subjects. The results suggest an evaluation paradigm with reference to etiologic determination for individuals with PDDs that does not presently justify metabolic or neuroimaging on a screening basis. Recurrence risk, treatment implications, and significant and long-lasting emotional relief for the parents suggest that serious consideration be given to clinical genetic examination, genetic testing, EEG study (during wakefulness and sleep), and audiometry, despite a relatively low yield. © 2006 Wiley-Liss, Inc. [source] Hearing of note: An electrophysiologic and psychoacoustic comparison of pitch discrimination between vocal and instrumental musiciansPSYCHOPHYSIOLOGY, Issue 6 2008Dee A. Nikjeh Abstract Cortical auditory evoked potentials of instrumental musicians suggest that music expertise modifies pitch processing, yet less is known about vocal musicians. Mismatch negativity (MMN) to pitch deviances and difference limen for frequency (DLF) were examined among 61 young adult women, including 20 vocalists, 21 instrumentalists, and 20 nonmusicians. Stimuli were harmonic tone complexes from the mid-female vocal range (C4,G4). MMN was elicited by multideviant paradigm. DLF was obtained by an adaptive psychophysical paradigm. Musicians detected pitch changes earlier and DLFs were 50% smaller than nonmusicians. Both vocal and instrumental musicians possess superior sensory-memory representations for acoustic parameters. Vocal musicians with instrumental training appear to have an auditory neural advantage over instrumental or vocal only musicians. An incidental finding reveals P3a as a sensitive index of music expertise. [source] Source localization of auditory evoked potentials after cochlear implantationPSYCHOPHYSIOLOGY, Issue 1 2008Stefan Debener Abstract Little is known about how the auditory cortex adapts to artificial input as provided by a cochlear implant (CI). We report the case of a 71-year-old profoundly deaf man, who has successfully used a unilateral CI for 4 years. Independent component analysis (ICA) of 61-channel EEG recordings could separate CI-related artifacts from auditory-evoked potentials (AEPs), even though it was the perfectly time-locked CI stimulation that caused the AEPs. AEP dipole source localization revealed contralaterally larger amplitudes in the P1,N1 range, similar to normal hearing individuals. In contrast to normal hearing individuals, the man with the CI showed a 20-ms shorter N1 latency ipsilaterally. We conclude that ICA allows the detailed study of AEPs in CI users. [source] Habituation of auditory evoked potentials in intracranial and extracranial recordingsPSYCHOPHYSIOLOGY, Issue 2 2006Timm Rosburg Abstract Effects of stimulus repetition are investigated in short-term habituation experiments. In these experiments, trains of stimuli are applied with longer intervals of no stimulation between the trains. In scalp recordings, an amplitude and latency decrease of the auditory N100 is usually observed at the beginning of the train. This contrasts to a recent finding with intracranial recordings, exhibiting an effect on N100 amplitude, but not on its latency. In the current study, P50 and N100 were simultaneously recorded intra- and extracranially in epilepsy patients. The amplitudes of P50 and N100 decreased in both recordings, whereas the P50 latency was not significantly affected. A latency decrease was revealed for the extracranially recorded N100, but not for the intracranial N100. This dissociation between the intracranial and scalp recordings might be explained by a different sensitivity of the two measurements for N100 generators. [source] An initial report of a new biological marker for bipolar disorder: P85 evoked brain potentialBIPOLAR DISORDERS, Issue 6 2009Julie V Patterson Objectives:, Progress toward understanding the neurobiological and genetic underpinnings of bipolar disorder has been limited by the scarcity of potential biological markers that predict its occurrence. A measure of the integrity of brain inhibitory function, sensory gating, measured using the amplitude of the evoked potential at 50 ms to the first of two paired clicks divided by the response to the second, has been characterized as a biological marker for schizophrenia. Currently, no such biological marker exists for bipolar disorder. The goal of this research was to determine how gating of an auditory brain potential at 85 ms (P85), not previously examined in sensory gating studies, differentiated control and patient groups. Methods:, P50 and P85 auditory evoked potentials were collected from individuals diagnosed with schizoaffective disorder (n = 45), paranoid schizophrenia (n = 66), and bipolar I disorder (n = 42) using DSM-IV criteria and the Structured Clinical Interview for DSM-IV; and from 56 healthy controls. Results:, The P85 gating ratio was significantly larger in the bipolar disorder group compared to each of the other groups (F3,204 = 5.47, p = 0.001, and post-hoc tests). The P50 gating ratio was significantly larger for the schizoaffective group than for the control group (F3,204 = 2.81, p = 0.040), but did not differ from the ratio for the schizophrenia, paranoid type (p = 0.08) and bipolar groups. Conclusions:, The previously unstudied P85 gating ratio may provide a new marker specific to bipolar disorder. The findings will promote further studies to investigate the unique contribution of this measure as an endophenotype. [source] | ||||||||||||||||