Auditory extinction to nonverbal and verbal stimuli

The so-called auditory extinction phenomenon in a verbal dichotic listening test was investigated in seven brain damaged patients from the qualitative standpoint. As the result, it became evident that the phenomenon could result from competition between verbal materials presented to both ears in at least two different levels of auditory processing i.e., sound perception and linguistic recognition. From the present study, we emphasize the following: If Bender's definition is followed, it is advisable to use the term extinction only for the phenomenon at the acoustic level. If the use of the term extinction for the phenomenon is to be continued at the linguistic level, the presence of auditory extinction and/or obscuration to nonverbal stimuli should be noted.     

Auditory and somatosensory evoked potentials (AEPs and SEPs) and ballistic movements in parkinson disease

In five patients with initial idiopathic Parkinson disease AEPs (early and late components of auditory evoked potentials), SEPs (somatosensory evoked potentials) and arm ballistic movements (abduction of the humerus) were studied. Experimental sessions were conducted before starting treatment (L-Dopa plus Carbidopa) and at two and six month intervals. Before treatment evoked potential abnormalities were found in four out of five patients; EMG patterns underlying ballistic arm abduction movements were altered in all patients; corresponding prolonged duration of initial movements and low mean velocities were found. After treatment AEP and SEP showed a reduction of previously observed abnormalities and both EMG patterns and kinematic variables consistently improved. It is suggested that the electrophysiological investigations employed in this preliminary study may be a useful tool in clinical and pharmacological researches on Parkinson disease.

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Sommario Sono stati studiati in 5 pazienti affetti da sindrome di Parkinson idiopatica iniziale gli AEPs (componenti precoci e tardive), i SEPs ed i movimenti balistici (abduzione dell'omero). Lo studio è stato condotto prima dell'inizio della terapia (L-Dopa+Carbidopa), e due e sei mesi dopo l'inizio della terapia. Anomalie dei potenziali evocati sono state riscontrate prima dell'inizio della terapia in 4 pazienti. I dati elettromiografici relativi ai movimenti balistici di abduzione del braccio erano alterati in tutti i pazienti ed erano caratterizzati da un ritardo nell'inizio del movimento e da una diminuizione della velocità media.Dopo la terapia si è rivelata una riduzione delle anomalie precedentemente riscontrate per gli AEPs ed i SEPs ed anche i patterns EMG e le variabili kinematiche sono apparse notevolmente migliorati. Dall'analisi di questi risulati sembra emergere la possibilità che queste metodiche neurofisiologiche possano essere utilizzate quale mezzo per controllare la progressione della sindrome e l'efficacia di eventuali trials farmacologici.

     

Auditory evoked potentials recorded intracranially from the brain stem in man

Auditory evoked potentials were recorded in patients undergoing neurosurgical operations to manage cranial nerve dysfunctions. Recordings were made intra-operatively from the distal portion of the eighth nerve, from the entrance of the eighth nerve into the brain stem, and from a site overlying the superior olivary complex (rostral and medial to the entrance of the eighth nerve). The potentials at the three different loci showed characteristic differences: the responses recorded at the entrance of the eighth nerve into the brain stem showed three peaks about 1 ms apart. The earliest peaks had longer latencies than did those recorded at a distal locus on the eighth nerve, which is consistent with what we know about propagation of nerve impulses in the auditory nerve. The responses recorded on the brain stem, rostral-medial to the eighth nerve, also showed three peaks but the amplitude of the third peak was greater than those of the other two. It is assumed that the first peak originates in the auditory nerve, the second peak in the cochlear nucleus, and the third peak in the lateral superior olive. The latencies of these peaks match the latencies of peaks II, III, and IV of scalp-recorded brain stem evoked potentials.     

Auditory evoked transient and sustained potentials in the human EEG: I. Effects of expectation of stimuli

The characteristics of auditory evoked transient and sustained potentials were recorded using trains of four-tone stimuli of 1-second duration (interstimulus interval = 1 second) presented once every minute. The subject either attentively expected the stimuli or ignored them while reading. The electroencephalogram was recorded from derivations Cz-Al and Fz-Al. Expectation of the stimuli was associated with increased amplitudes of the transient responses both at the first stimulus of the train and during stimulus repetition. In contrast, the sustained potential at the first stimulus of the train was unchanged or smaller when the subject expected the stimuli. During stimulus repetition, however, the amplitude of the potential was enhanced by expectation of the stimuli. The results support the hypothesis of two sustained potential components and stress the importance of stimulus repetition rate when sustained potentials are studied.     

正常成人处于气功态和催眠态脑诱发电位实验研究

目的　观察 4 9例正常成人处于“正常态”、“气功入静态”和“催眠状态”的脑诱发电位 ,分析气功发功和催眠诱导对大脑生理过程的不同效应。方法　观察视觉诱发电位 (VEP)、听觉诱发电位(AEP)、听觉脑干诱发电位 (ABR)、关联性负变 (CNV)和P3 0 0 的潜伏期和波幅。结果　催眠状态下P3 0 0(T P3 )波幅降低 ,与正常态相比有极显著差异 (P <0 .0 1) ;AEP(P2 ) ,CNV(M2 )波幅降低 ,与正常态和气功入静态相比均存在显著差异 (P <0 .0 5 ) ;VEP(P2 、P3 )波幅降低 ,与正常态或气功入静态相比分别存在显著差异 (P <0 .0 5 )。结论　催眠诱导对大脑生理过程的影响与气功发功存在差别。     

Auditory evoked potentials to speech and nonspeech stimuli are associated with verbal skills in preschoolers

Children’s obligatory auditory event-related potentials (ERPs) to speech and nonspeech sounds have been shown to associate with reading performance in children at risk or with dyslexia and their controls. However, very little is known of the cognitive processes these responses reflect. To investigate this question, we recorded ERPs to semisynthetic syllables and their acoustically matched nonspeech counterparts in 63 typically developed preschoolers, and assessed their verbal skills with an extensive set of neurocognitive tests. P1 and N2 amplitudes were larger for nonspeech than speech stimuli, whereas the opposite was true for N4. Furthermore, left-lateralized P1s were associated with better phonological and prereading skills, and larger P1s to nonspeech than speech stimuli with poorer verbal reasoning performance. Moreover, left-lateralized N2s, and equal-sized N4s to both speech and nonspeech stimuli were associated with slower naming. In contrast, children with equal-sized N2 amplitudes at left and right scalp locations, and larger N4s for speech than nonspeech stimuli, performed fastest. We discuss the possibility that children&rsquo;s ERPs reflect not only neural encoding of sounds, but also sound quality processing, memory-trace construction, and lexical access. The results also corroborate previous findings that speech and nonspeech sounds are processed by at least partially distinct neural substrates.     

Brain stem auditory and visual evoked potentials in multiple sclerosis

The diagnostic value of the checkerboard pattern-reversal visual evoked potential (VEP) and the random, low rate stimulated brain stem auditory evoked potential (BAEP) was compared in 99 patients with established or suspected multiple sclerosis (MS). In normal subjects examined by both techniques no abnormal recordings were found. In 49 patients with definite MS an incidence of abnormality was found in 100% of VEP and in 84% of BAEP recordings. In 50 patients with probable or possible MS an abnormal VEP was found in 70% and an abnormal BAEP in 50%. When the two examinations were combined, the diagnostic yield increased to 100 and 80%, respectively. 22 patients had only spinal symptoms; in these the VEP gave 73%, the BAEP 55% and the combination 82% abnormalities. The combination of the two techniques was found useful for demonstrating demyelinating lesions in the central nervous system, the diagnostic value being greatest when these lesions were clinically silent.     

Changes in subcortical visual and auditory evoked potentials following amygdaloid kindling in cats

In this study we dealt with the changes in visual and auditory evoked potentials following kindling, to reveal the distant effects of epileptic activity. The experiments were performed using cats. Visual and auditory evoked potentials were obtained initially. Daily stimulation of 60 Hz (rectangular wave, 1 ms in duration, 500 microA in peak current, 2-s train) was given to the right amygdala, for kindling. After the completion of kindling, evoked responses were recorded again. In the auditory system the changes of responses in the cortex, medial geniculate nucleus, and cochlear nucleus were distinguished. The changes of potentials in the subcortex were larger than those at the cortical level. For visual evoked potentials there was a discrepancy between stimulation with light and electrical stimulation of the optic chiasm. There was no significant change in amplitude of visual evoked potentials by flash. In the case of optic chiasm stimulation, an enlargement of evoked responses was obtained. These results indicate modality-specific change of the auditory system and widespread subcortical change. These results might be caused by some vulnerability of the auditory system in the case of amygdaloid kindling, as a result of the epileptogenic process.     

Role of inter-trial phase coherence in atypical auditory evoked potentials to speech and nonspeech stimuli in children with autism

Objective

This autism study investigated how inter-trial phase coherence (ITPC) drives abnormalities in auditory evoked potential (AEP) responses for speech and nonspeech stimuli.

Variations of brain stem auditory evoked potentials correlated to duration and severity of multiple sclerosis

A total of 158 recordings of brain stem auditory evoked potentials (BAEPs) were obtained in 121 patients with multiple sclerosis. A statistically significant increased incidence of abnormality and diffusely abnormal recordings was found with increasing duration and severity of symptoms. Alterations in follow-up recordings might reflect changes in the clinical state, but also occurred in clinically stable patients. These findings suggested that transition from normality of BAEPs might occur either by successive disappearance of the later waves or by uniformly decreasing amplitudes of all the waves to diffusely abnormal recordings. It was concluded that the main value of BAEP recording in patients with multiple sclerosis was to indicate clinically silent lesions, and its value in monitoring the clinical condition of the individual patient was dubious.     

Brain-stem auditory evoked potentials in multiple sclerosis: the relation to VEP,SEP and CSF immunoglobulins

Summary One hundred patients with multiple sclerosis (MS) were analysed retrospectively with respect to investigations of brain-stem auditory evoked potentials (BAEP), pattern reversal visual evoked potentials (VEP), somatosensory evoked potentials (SEP), and cerebrospinal fluid immunoglobulins (CSF-IG). BAEP were abnormal in 42% of those with normal VEP and SEP examinations, and in 38% of patients with normal CSF-IG. The chance of obtaining at least one abnormal EP was lower in patients with normal CSF-IG than in patients with abnormal CSF. When a dispersion ratio was included in the criteria for BAEP abnormality, the sensitivity increased compared with conventional BAEP criteria. We recommend that BAEP should still be included in the EP test battery for patients with suspected MS.     

Evaluation and graduation of brain stem auditory evoked potentials in patients with neurological diseases

Based on normative data from 40 subjects, criteria for evaluating brain stem auditory evoked potentials have been elaborated. This system contained six grades from normal to diffusely abnormal, and was used in evaluating recordings from 142 patients, including 38 patients with definite and 48 with probable and possible multiple sclerosis, 18 patients with brain stem infarctions, six patients with other organic brain stem lesions, six patients with a postcommotional syndrome and 26 patients without any brain stem involvement. A statistically significant difference was found between normal persons and patients without evidence of brain stem lesions versus patients with such evidence, as well as between subgroups of slightly and severely affected patients. The system was found useful as a way of describing recordings, in company groups of patients and in a follow up of a few patients.     

The value of brain stem auditory, visual and somatosensory evoked potentials and blink reflexes in the diagnosis of multiple sclerosis

Cervical and cortical somatosensory evoked potentials (SEP) following electrical stimulation of the median nerve and blink reflexes (BR) following electrical stimulation of the supraorbital nerve were recorded in 30 normal subjects aged 20–49 years. Subjects aged 40–49 had longer SEP latencies than subjects aged 20–39 years.
A total of 29 slightly affected patients with multiple sclerosis (MS) aged 26–49 years, including four patients without clinical signs (suspected MS) and 19 patients with signs indicating only one lesion (possible MS) were examined by low-rate random-stimulated brain stem auditory (BAEP), checkerboard pattern-reversal visual evoked potentials (VEP), SEP and BR. Abnormal recordings by at least one of the examinations were found in all but three patients, and by all four tests in five patients.
In patients with definite or probable MS, demonstration of clinically recognized or subclinical lesions was of minor diagnostic value, in contrast to the importance such findings had in patients with suspected or possible MS. Silent lesions were shown by at least one of the tests in the four suspected and in 13 of the possible MS patients, so these 17 patients could be transferred to a more certain diagnostic category. This reclassification was most often due to the BAEP recording.
In patients with spinal signs, the combination of BAEP and VEP recording was sufficiently efficient. In patients with optic neuritis a combination of BAEP and SEP was preferred. No abnormal recordings were found in 15 normal subjects examined by all four tests.     

The comparative analyses of the auditory evoked potentials and color Doppler sonography findings in patients diagnosed with vertebrobasilar insufficiency

Abstract

Auditory evoked potentials (AEP) represent an electrophysiological method used in the diagnostics of pathological changes of the brainstem. Patients with vertebrobasilar insufficiency (VBI) show changes in the AEP-caused ischemia of the brain structures that generate their responses.

The aim of the study was to determine the diagnostic significance and correlation among the findings of AEP in patients with VBI established by color Doppler sonography.

The cross-sectional and prospective research included 48 inpatients and outpatients treated at the Clinic of Neurology, Clinical Center Nis. Ultrasound Doppler of blood vessels in the neck included an examination of the carotid blood vessels, the outcome and all sonographically available parts of the vertebral artery (VA) with particular emphasis on the intravertebral segment (V2). The morphological and hemodynamic characteristics of VA in this segment were monitored, and it was important to test the systolic velocity in two adjacent intervertebral spaces. Auditory evoked potentials were used to monitor the amplitudes, absolute latencies of waves I, II, III, IV, and V, as well as interwave latencies (IWLs) I–III, III–V, and I–V.

There is statistically significant difference in the more frequent pathological finding of AEP in patients with higher degree of the reduced flow of VA established by color Doppler (P < 0·05) compared to patients with less reduction in the flow. Pathological findings of AEP are well correlated with pathological findings of VBI in color Doppler, and it may be applied as an additional and useful marker in diagnosis of VBI.     

Auditory evoked brain potentials as markers of chronic effects of mild traumatic brain injury in mid-life

ObjectiveAuditory event-related potential (ERP) correlates of pre-dementia in late-life may also be sensitive to chronic effects of mild traumatic brain injury (mTBI) in mid-life. In addition to mTBI history, other clinical factors may also influence ERP measures of brain function. This study’s objective was to evaluate the relationship between mTBI history, auditory ERP metrics, and common comorbidities.MethodsERPs elicited during an auditory target detection task, psychological symptoms, and hearing sensitivity were collected in 152 combat-exposed veterans and service members, as part of a prospective observational cohort study. Participants, with an average age of 43.6 years, were grouped according to positive (n = 110) or negative (n = 42) mTBI history. Positive histories were subcategorized into repetitive mTBI (3 + ) (n = 40) or non-repetitive (1–2) (n = 70).ResultsPositive history of mTBI was associated with reduced N200 amplitude to targets and novel distractors. In participants with repetitive mTBI compared to non-repetitive and no mTBI, P50 was larger in response to nontargets and N100 was smaller in response to nontargets and targets. Changes in N200 were mediated by depression and anxiety symptoms and hearing loss, with no evidence of a supplementary direct mTBI pathway.ConclusionsAuditory brain function differed between the positive and negative mTBI groups, especially for repetitive injury, which implicated more basic, early auditory processing than did any mTBI exposure. Symptoms of internalizing psychopathology (depression and anxiety) and hearing loss are implicated in mTBI’s diminished brain responses to behaviorally relevant and novel stimuli.SignificanceA mid-life neurologic vulnerability conferred by mTBI, particularly repetitive mTBI, may be detectable using auditory brain potentials, and so auditory ERPs are a target for study of dementia risk in this population.     

Event-related potentials to repeated speech in 9-month-old infants at risk for autism spectrum disorder

Background

Atypical neural responses to repeated auditory and linguistic stimuli have been reported both in individuals with autism spectrum disorder (ASD) and their first-degree relatives. Recent work suggests that the younger siblings of children with ASD have atypical event-related potentials (ERPs) to repeated tones at 9 months of age; however, the functional significance is unclear, and it is unknown whether this atypicality is also present in response to linguistic stimuli.

Methods

We analyzed ERPs to repetitive and deviant consonant-vowel stimuli at 9 months in 35 unaffected high-risk-for-autism (HRA) infant siblings of children with ASD and 45 low-risk control (LRC) infants. We examined a positive component, the P150, over frontal and central electrode sites and investigated the relationships between this component and later behavior.

Results

Over frontal electrodes, HRA infants had larger-amplitude ERPs to repetitions of the standard than LRC infants, whereas ERPs to the deviant did not differ between HRA and LRC infants. Furthermore, for HRA infants, the amplitude of ERPs to the standards was positively correlated with later language ability.

Conclusions

Our work suggests that atypical ERPs to repeated speech during infancy are a possible endophenotype of ASD but that this atypicality is associated with beneficial, rather than disordered, language development. Potential mechanisms driving these relationships and implications for development are discussed.     

Auditory evoked potentials in schizophrenic patients before and during neuroleptic treatment

Summary The auditory evoked potential (AEP) components N1 and P2 were investigated under a no-task condition in a group of 14 acutely ill unmedicated schizophrenic patients and compared with the findings in an age- and sex-matched control group. In the patients, N1 latency was significantly increased, P2 latency and N1-P2 interpeak latency were reduced. There were significant relationships between AEP parameters and the psychopathological state evaluated by means of the brief psychiatric ratings scale (BPRS). The N1 and P2 latencies were negatively correlated with the BPRS subscore anergia and positively correlated with agitation. In 8 of the patients, a standardized neuroleptic treatment was started with 10 mg haloperidol/day. After 2 weeks of treatment, BPRS scores and N1 amplitude had significantly decreased. However, there was no relationship between BPRS improvement and N1 amplitude reduction. N1 latency in the unmedicated state was negatively correlated with subsequent therapeutic response measured as proportional improvement of the BPRS score within 2 weeks. Thus, N1 latency may be seen as a psychophysiological measure with prognostic applications.     

Motor evoked potentials to magnetic stimulation: technical considerations and normative data from 50 subjects

Summary Magnetic stimulation of the brain and cervical and lumbar spinal roots was performed on 50 healthy volunteers. Compound muscle action potentials (CMAPs) were recorded from biceps brachii, abductor digiti minimi (ADM), rectus femoris and tibiahs anterior (TA). We assessed central conduction times by subtraction of peripheral from central latencies and compared results using either spinal root stimulation or the F-wave method. Side-to-side differences of total conduction time, peripheral conduction time and central conduction time (CCT) were measured and the effect of clockwise vs counterclockwise stimulations on latencies and sizes of CMAPs is emphasized. Amplitudes and areas of CMAPs were expressed as a percentage of the peripheral M response for ADM and TA. There was a positive correlation between CCT to the lumbosacral region and height, but not between the cervical region and height. No correlation was observed between genders and central conduction times, amplitudes or areas of CMAPs.