ERP assessment of visual and auditory language processing in schizophrenia.

Language disturbance in schizophrenia has been recently attributed to disturbed priming mechanisms. In the present study, event-related potentials (ERPs), were recorded to final words in sentences presented to 13 chronic patients with schizophrenia and 12 normal controls. Half of the final words fit a sentence context and another half did not. The N400 (the ERP sensitive to language) latency was prolonged, and its amplitude was more negative to both correct and incorrect sentence endings in the group with schizophrenia relative to the group of normal controls. The early ERP components, N100 and P200, were similar in both groups. These results suggest that language abnormalities in schizophrenia are related to a dysfunction in the language system and not to a general cognitive dysfunction, and may be related to poor use of context in patients with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parkinson's dementia and Alzheimer's dementia: an evoked potential comparison

Auditory endogenous event-related potentials (ERPs) and flash visual evoked potentials (VEPs) were recorded in 26 elderly patients with idiopathic Parkinson's disease (PD), 14 with dementia and 12 non-demented, 16 elderly patients with Alzheimer dementia (AD) and 15 cognitively intact controls. ERP P3 and flash-VEP N2, P2 and delta (P2-P1) latency measures were significantly increased in the demented PD group compared with controls. The ERP P3 latency was also significantly delayed in the AD group compared with controls, but the differences in the flash-VEP measures from controls were not significant. No significant differences were noted between the PD groups, except for a significantly shorter flash-VEP N1 latency in the demented PD group; this was also the only significant evoked potential difference between the AD and PD dementia groups, which were otherwise electrophysiologically similar.     

Event-related potential measures of 24-hour retention in 5-month-old infants.

Two experiments using event-related potentials (ERPs) investigated 24-hr recognition memory in infants. In each, ERPs were recorded to 100 identical stimuli in 5-mo-olds. After 24 hrs, 50 of these familiar stimuli and 50 novel stimuli were presented. In Exp 1, the 2 stimuli were a tone and a click. The amplitude of a negative peak (N2; approximate latency?=?350 msec) of the auditory ERP was larger on Day 2 for the familiar stimuli compared with ERPs for both Day 1-familiar stimuli and Day 2-novel stimuli. Trial-to-trial latency variability of N2 decreased from Day 1 to Day 2 for the familiar stimuli. In Exp 2, 2 tones differing only in frequency (pitch) were used. The results replicated those of Exp 1. In addition, an earlier positive peak (P2; approximate latency?=?200 msec) showed larger amplitudes and smaller latency variability to the familiar stimulus on Day 2. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human in vivo somatic mutation measured at two loci: individuals with stably elevated background erythrocyte glycophorin A (gpa) variant frequencies exhibit normal T-lymphocyte hprt mutant frequencies

The P3 event-related potential (ERP) component was recorded from 7- to 18-year-old children of alcoholics (COAs, n = 50) and age- and sex-matched control children (n = 50) using a visual oddball paradigm, involving nontarget (76%), target (12%), and novel (12%) stimuli. Topographic maps of P3 and associated scalp current density were obtained to supplement a topographic profile analysis. COAs manifested a smaller amplitude P3 to target stimuli over the centroparietal, parietal, and occipital scalp locations than controls. Also, COAs exhibited a smaller amplitude P3 to novel stimuli over the occipital scalp than controls. There were no significant differences between COAs and controls in the P3 scalp topography, indicating that differences in intracranial source strength rather than in source configuration were responsible for the between-group amplitude differences. Also, no significant group differences were observed in the P3 peak latency or in behavioral performance. These results support the notion that the visual P3 may provide a vulnerability marker of alcoholism.     

P300, handedness, and corpus callosal size: gender, modality, and task

The P300 event-related potential (ERP) was elicited in left- and right-handed young adult male and female subjects (n = 20/group), with auditory and visual stimulus modalities from single-stimulus and oddball tasks. P300 amplitude was larger across all conditions for left- compared to right-handed subjects at anterior and central electrode sites. P300 latency was shorter across all conditions for left- compared to right-handers. Task type did not affect the ERP handedness differences. Male and female subjects demonstrated comparable ERP handedness effects, although smaller P300 components were obtained for males compared to females. When considered in the context of previously reported corpus callosal size differences for left- vs. right-handed and male vs. female participants, the findings suggest that the P300 reflects callosal size and inter-hemispheric transmission efficacy.     

The relation of ERP components to complex memory processing

The relation between various ERP components generated during encoding of a word and its subsequent recall were investigated using a "rote" serial-order and an "elaborative" category memory task. Words (flashed separately) were time-locked to EEG recordings from 21 cortical sites. ERP components from the five subjects having the highest recall scores were compared to the five lowest scoring subjects. Results based on the P200 peak amplitude data as well as the N400 and late positive component peak amplitude and latency data suggest that anterior and posterior distributional differences are elicited during encoding of words for rote and elaborative memory tasks. Furthermore, strong individual differences in these patterns were found as a function of task. A tentative argument was made that the obtained anterior and posterior differences may index different word feature selection and encoding processes, which are differentially utilized by high and low recallers.     

ERPs in schizophrenia: effects of antipsychotic medication

Thirty unmedicated schizophrenics were compared to 29 age-matched controls on auditory and visual event-related brain potential (ERP) paradigms. Twenty-one of these patients were tested again after 1 week on placebo and after 4 weeks on antipsychotic medication. Before treatment, N1, N2, and P3 components of the auditory ERP were smaller in the schizophrenics than in the controls. Although visual N2 was smaller in schizophrenics, visual P3 was not. In spite of significant clinical improvement with antipsychotic treatment, amplitudes of auditory and visual N1, N2, and P3 were not significantly changed. Higher blood levels of antipsychotic medication were related to reductions in auditory P3 latency, however. In addition, higher levels of cerebrospinal fluid (CSF) MHPG (methoxyhydroxyphenylglycol) were associated with larger auditory N1s and larger auditory and visual P3s, suggesting an influence of arousal on these components in schizophrenics. In spite of this influence, reduction of the auditory P3 in schizophrenia is an enduring trait of the disease, which is not affected by antipsychotic medication or clinical improvement.     

Microsurgical C-2 ganglionectomy for chronic intractable occipital pain

The P300 event-related brain potential (ERP) was elicited with visual stimuli using an oddball task in which the subjects made button press responses to discriminate target and standard stimuli. Each stimulus occurred randomly with a 0.50 probability, and 10 trial blocks were presented at 10-min inter-block-intervals (IBIs). P300 amplitude declined reliably across trial blocks, and an interaction between trial block number and electrode site was observed. No habituation effects were found for P300 latency or for N100, P200, or N200 amplitude. The results suggest that P300 amplitude from visual stimuli habituates when short IBIs and a sufficient number of trial blocks are employed. Theoretical implications are discussed with respect to attentional resource allocation and context updating.     

Microvasculature of crotaline snake pit organs: possible function as a heat exchange mechanism

BACKGROUND: Lasting cognitive dysfunction throughout remission has been regarded as a biological vulnerability in schizophrenia, which may produce psychotic relapses with characteristic symptoms. Our hypothesis was that an abnormality in event-related potentials (ERPs) may be a neurophysiological marker of vulnerability to psychotic relapse in remitted schizophrenia. We conducted a 2-year follow-up study after evaluating ERP abnormalities to find a new ERP marker for schizophrenic relapse. METHODS: Visual ERPs were recorded from outpatients with remitted schizophrenia under maintenance pharmacotherapy (n = 44) and normal controls (n = 20) during a letter discrimination task. Based on the prospective study, the patients were divided into a relapse group (n = 20) and a nonrelapse group (n = 24). ERP findings that related to psychotic relapse within 2 years were analyzed. RESULTS: Compared with controls, the relapsers showed ERP abnormalities in the NA, N2, and P3 components, and the nonrelapsers in the P3 component. The peak latency of the NA potential was delayed significantly in the relapse group relative to the nonrelapse group, and predicted a psychotic relapse with about 90% probability. CONCLUSIONS: The delayed NA, which reflects early perceptual disorganization, may be a promising neurophysiological predictor of psychotic relapse in remitted schizophrenia under maintenance pharmacotherapy.     

Brain potentials as indices of orthographic and phonological interaction during word matching.

Studied the interaction between orthographic and phonological codes in a same–different judgment task by requiring 40 undergraduates to decide if 2 visually presented words either looked alike or rhymed. Word pairs were selected from 4 lists: words rhymed and looked alike, rhymed but did not look alike, looked alike but did not rhyme, or neither looked alike nor rhymed. The reaction time (RT) and percent error increased when there was a conflict between the orthography and phonology of the words. The N200 component of the event-related brain potential (ERP) indicated that Ss were capable of detecting phonological differences between words within 260 msec from the presentation of a word pair. The amplitude of the N200s also varied with the degree of mismatch between words. N200s were largest when both the orthography and phonology mismatched, of intermediate amplitude when either orthography or phonology mismatched, and smallest when both orthograpy and phonology matched. P300 latency was consistent with RT, increasing whenever there was a conflict between the 2 codes. Behavioral measures and the ERP data suggest that the extraction of the orthographic and phonological aspects of words occurs early in the information-processing sequence. (55 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual event-related potentials in schizotypal personality disorder and schizophrenia.

Schizophrenia (SZ) occurs among a spectrum of disorders with similar characteristics, including schizotypal personality disorder (SPD). Visual processing disturbances have been reported in both disorders, but it is not yet clear which processes are disturbed in both SZ and SPD, suggestive of a common endophenotype, and which appear only in SZ. In order to address this question, the authors evaluated visual event-related potentials (ERPs) elicited during a line-orientation discrimination task in control, SPD, and SZ participants. Visual ERPs allow specification of both the time course and physiological correlates of visual perception and cognition. SZ patients had smaller P100 and P300a amplitudes and prolonged P300b latency compared to the control group. SZ patients also had smaller N160, N200, P300a, and P300b amplitudes compared to the SPD group. SPD participants did not differ from control participants on any ERP measure. These data documented pervasive abnormalities in visual perception and attention in SZ but not in SPD, suggesting that these visual ERP disturbances may not represent a common endophenotype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory event-related potentials in Parkinson's disease

We studied 49 patients with Parkinson's disease (PD) by a neuropsychological battery examining the temporo-spatial orientation, short-term memory, comprehension, non-verbal intelligence, long-term memory and anomia and the Auditory Event-Related Potentials. In the patients the latencies of the N100 and N200 waves were prolonged and the amplitude of the P300 wave was reduced compared with controls. No difference was found in the ERP of patients with and without cognitive deficits. Equally, no correlation was found between the ERP, the cognitive impairment, the length or the severity of the disease evaluated by Hoehn-Yahr's and Webster's scales.     

Electrophysiological indices of information processing in methylphenidate responders

Event-related potential (ERP) studies report that the positive deflection following stimulus evaluation at 300 msec (P3) in hyperactive children is augmented by methylphenidate (MP). This study investigates P3 and preceding ERP components using an auditory oddball task in attention-deficit hyperactivity disorder (ADHD). Mismatch negativity, negativity at 100 and 200 msec, and positivity at 200 msec and 300 msec (P3) were obtained from 14 control and hyperkinetic children. ADHD children who responded to MP were tested on two separate days while receiving either MP or placebo. Controls were tested once. No differences were found between groups for ERP components preceding P3. P3 amplitude was significantly larger under MP than under placebo, but did not differ from controls. Under MP, differences in P3 amplitude unexpectedly occurred when no response was required. A P3 amplitude increase under MP and the unexpected P3 suggest that MP affects attention regulation.     

Personality, reaction time, and event-related potentials.

Reaction time (RT), movement time (MT), and the amplitude and latency of the P300 ERP were recorded from 30 Ss during the performance of 6 simple cognitive tasks. Extraversion was negatively associated with MT, a result that endorses the view that extraversion is determined, in part, by individual differences in motor mechanisms. Higher neuroticism scores were associated with faster P300 latency, a measure that is regarded as an index of stimulus evaluation time that is independent of response production. Paradoxically, higher neuroticism scores were associated with slower RT, a measure that is also regarded as an index of speed of information processing. Higher psychoticism scores were associated with smaller P300 amplitude, an effect that may be indicative of less attentional effort invested in the tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Markers from event-related potential subcomponents and reaction time for information processing dysfunction in schizophrenia

Event-related potentials (ERPs) can serve as markers for cognitive processing stages. Identification of those ERPs altered in schizophrenia offer information about cognitive dysfunction. Auditory evoked potentials (AEPs) were elicited within an oddball paradigm in 35 schizophrenic patients and compared with 35 healthy controls. N100 and P200, as well as N200, frontal P300 and parietal P300 subcomponents, were separated using dipole source analysis. The amplitudes of the N100 and the parietal P300 measured in schizophrenics were diminished. The input-related processing stages (N100 and P200) were not altered, whereas later, the deviant and task-related processes (N200, frontal P300, parietal P300 and reaction time) were significantly prolonged in schizophrenia.     

Does audiovisual speech offer a fountain of youth for old ears? An event-related brain potential study of age differences in audiovisual speech perception.

The current study addressed the question whether audiovisual (AV) speech can improve speech perception in older and younger adults in a noisy environment. Event-related potentials (ERPs) were recorded to investigate age-related differences in the processes underlying AV speech perception. Participants performed an object categorization task in three conditions, namely auditory-only (A), visual-only (V), and AVspeech. Both age groups revealed an equivalent behavioral AVspeech benefit over unisensory trials. ERP analyses revealed an amplitude reduction of the auditory P1 and N1 on AVspeech trials relative to the summed unisensory (A + V) response in both age groups. These amplitude reductions are interpreted as an indication of multisensory efficiency as fewer neural resources were recruited to achieve better performance. Of interest, the observed P1 amplitude reduction was larger in older adults. Younger and older adults also showed an earlier auditory N1 in AVspeech relative to A and A + V trials, an effect that was again greater in the older adults. The degree of multisensory latency shift was predicted by basic auditory functioning (i.e., higher hearing thresholds were associated with larger latency shifts) in both age groups. Together, the results show that AV speech processing is not only intact in older adults, but that the facilitation of neural responses occurs earlier in and to a greater extent than in younger adults. Thus, older adults appear to benefit more from additional visual speech cues than younger adults, possibly to compensate for more impoverished unisensory inputs because of sensory aging. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Alcohol abuse and traumatic brain injury: effect on event-related potentials

OBJECTIVE: To examine the individual and combined impact that traumatic brain injury (TBI) and heavy social use of alcohol have on electrophysiologic correlates of working memory and evaluation of task-relevant information. DESIGN: Case-control study. SETTING: University hospital brain injury rehabilitation unit. PARTICIPANTS: Forty male volunteers divided into four groups on the basis of their history of TBI and alcohol intake. Subjects with TBI had experienced a severe closed head injury at least 1 year before testing. MAIN OUTCOME MEASURE: Event-related potentials (ERPs) and neuropsychometric tests. RESULTS: Groups showed no significant differences in average age or neuropsychological tests. TBI groups did not differ in time postinjury or on severity measures. Alcohol use measures were significantly greater in the two alcohol groups. N200 latency and P300 amplitude were impaired in heavy social drinkers and in nondrinking subjects with TBI relative to controls, but were significantly impaired in subjects with TBI who were also heavy social drinkers. CONCLUSION: The results indicate that although alcohol use and TBI independently produce mile alterations in some aspects of late ERP components, the ERP changes are significantly greater when alcohol use and TBI are combined. This study provides evidence that heavy social drinking after TBI has a measurable impact on electrophysiologic correlates of cognition.     

Auditory event related potentials in major depression: prolonged P300 latency and increased P200 amplitude

BACKGROUND: Some studies have shown disturbances in auditory event related potentials (AERPs) in patients with major depression. METHODS: In this exploratory study, the late AERP components, N100 (latency), P200 (amplitude and latency) and P300 (amplitude and latency) were recorded in 68 subjects, i.e. 39 major depressed subjects, with (n=4) or without (n=35) cognitive deterioration, 18 patients with Alzheimer's dementia (SDAT) and 11 normal volunteers. Twenty-five major depressed patients had repeated measurements of AERPs both before and after treatment with antidepressants. RESULTS: Major depressed subjects without cognitive deterioration had significantly higher P300 latency and P200 amplitude than normal volunteers. SDAT patients and major depressed patients with cognitive impairment had a significantly higher P300 latency than depressed patients without cognitive impairment. In the latter, no significant alterations in any of the AERP components upon subchronic treatment with antidepressants were recorded. Nonresponders to antidepressant therapy had significantly higher pretreatment P300 latency and P200 amplitude than responders to treatment (P=0.006) and normal volunteers (P=0.0004). CONCLUSIONS: The findings may suggest that delayed P300 latency as well as increased P200 amplitude accompany major depression and may predict a nonresponse to subsequent antidepressive therapy.     

Event-related potential correlates of linguistic information processing in schizophrenics

Event-related potentials (ERPs) were recorded from adult schizophrenics and age- and education-matched normal controls during performance of an idiom recognition task involving judgments of the meaningfulness of idiomatic, literal, and nonsense phrases. Schizophrenics produced more errors and had prolonged reaction times while attempting to correctly differentiate meaningful from meaningless phrases. An ERP correlate of that deficit was a larger than normal N400 to idioms and literals, with no difference in N400 amplitude to nonsense phrases. This result was interpreted as evidence that the influence of the linguistic context provided by the first word of two-word idiomatic and literal phrases is reduced in schizophrenia. Schizophrenics also showed reduced amplitude P300.     

Morphological variations of the human gastric mucosa after omeprazole treatment: a scanning electron microscopic study

The effects of antiepileptic drugs on cognitive function in 48 healthy volunteers were assessed using event-related potentials (ERP) and the Attention Index included in the Wechsler Memory Scale, revised edition (WMS-R). The study was conducted over 1 week, using a double-blind design. Four drugs, carbamazepine (CBZ), phenytoin (PHT), valproate (VPA) and zonisamide (ZNS) were tested. Using an auditory oddball task, ERP measurements were made under two conditions with different tone intensities: Condition 1 used 70 db SPL; and Condition 2 used 30 db SPL. Results showed that CBZ prolonged target N1 and P3 latencies in Condition 1, and reduced frequent N1 amplitude in Condition 2, which suggests that CBZ may cause a change in sensory memory and prolong stimulus evaluation time. It is suggested that under a low stimulus intensity level, the sensory function itself was affected. Phenytoin was found to prolong target N1 latency in Condition 2, which also indicates a change in the sensory memory function. However, VPA did not significantly affect ERP components, except for the shortened frequent N1 latency, which could not be explained due to the limited information. It was found that ZNS augmented P3 amplitude in Condition 2, and reduced scores on the Attention Index. It is suggested that the augmentation of P3 amplitude was caused by the reduction of processing negativity as a result of the detrimental effect of ZNS on subjects' attention. However, the apparent difference between the ERP and behavioral indices suggests that caution should be exercised in assessing the results obtained only from ERP measurements.