Event-related Potentials Parameters Research Articles

The relationship between event-related potentials, stress perception and personality type in patients with multiple sclerosis without cognitive impairment: A pilot study.

The clinical course of multiple sclerosis (MS) can vary significantly among patients and is affected by exogenous and endogenous factors. Among these, stress and personality type have been gaining more attention. The aim of this study was to investigate the parameters of event-related potentials (ERPs) with regards to stress perception and personality type, as well as cognitive performance in MS patients. The study group consisted of 30 MS patients and 26 healthy controls. Auditory ERPs were performed in both groups, including an analysis of P300 and N200 response parameters. The Perceived Stress Scale (PSS) was used in the MS group to measure the perception of stress. The D-type Scale (DS14) scale was used to determine the features of Type D personality, characterized by social inhibition and negative affectivity. The score on the PSS corresponded with a moderate or high level of stress perception in 63% of MS patients, while 23% of patients presented with a Type D personality. P300 latencies were significantly longer (p = 0.001), N200 amplitudes were significantly higher (p = 0.004), and N200 latencies were longer in MS patients than in the controls. Strong positive correlations were found between N200 and P300 amplitudes, as well as between the DS14 and PSS results. Most MS patients experience moderate to severe stress. ERP abnormalities were found in MS patients who did not have overt cognitive impairment and showed correlations with stress levels and negative affectivity. Event-related potentials may be useful in assessing the influence of stress and emotions on the course of MS.

Effects of Subanesthetic Ketamine Administration on Visual and Auditory Event-Related Potentials (ERP) in Humans: A Systematic Review.

Ketamine is a non-competitive N-Methyl-D-Aspartate (NMDA) receptor antagonist whose effect in subanesthetic doses has been studied for chronic pain and mood disorders treatment. It has been proposed that ketamine could change the perception of nociceptive stimuli by modulating the cortical connectivity and altering the top-down mechanisms that control conscious pain perception. As this is a strictly central effect, it would be relevant to provide fresh insight into ketamine's effect on cortical response to external stimuli. Event-related potentials (ERPs) reflect the combined synchronic activity of postsynaptic potentials of many cortical pyramidal neurons similarly oriented, being a well-established technique to study cortical responses to sensory input. Therefore, the aim of this study was to examine the current evidence of subanesthetic ketamine doses on patterns of cortical activity based on ERPs in healthy subjects. To answer the question whether ERPs could be potential markers of the cortical effects of ketamine, we conducted a systematic review of ketamine's effect on ERPs after single and repeated doses. We have searched PubMed, EMBASE and Cochrane Databases and pre-selected 141 articles, 18 of which met the inclusion criteria. Our findings suggest that after ketamine administration some ERP parameters are reduced (reduced N2, P2, and P3 amplitudes, PN and MMN) while others remain stable or are even increased (P50 reduction, PPI, P1, and N1 amplitudes). The current understanding of these effects is that ketamine alters the perceived contrast between distinct visual and auditory stimuli. The analgesic effect of ketamine might also be influenced by a decreased affective discrimination of sensorial information, a finding from studies using ketamine as a model for schizophrenia, but that can give an important hint not only for the treatment of mood disorders, but also to treat pain and ketamine abuse.

Selective attention and the "Asynchrony Theory" in native Hebrew-speaking adult dyslexics: Behavioral and ERPs measures.

The main aim of the present study was to determine whether adult dyslexic readers demonstrate the "Asynchrony Theory" (Breznitz [Reading Fluency: Synchronization of Processes, Lawrence Erlbaum and Associates, Mahwah, NJ, USA, 2006]) when selective attention is studied. Event-related potentials (ERPs) and behavioral parameters were collected from nonimpaired readers group and dyslexic readers group performing alphabetic and nonalphabetic tasks. The dyslexic readers group was found to demonstrate asynchrony between the auditory and the visual modalities when it came to processing alphabetic stimuli. These findings were found both for behavioral and ERPs parameters. Unlike the dyslexic readers, the nonimpaired readers showed synchronized speed of processing in the auditory and the visual modalities while processing alphabetic stimuli. The current study suggests that established reading is dependent on a synchronization between the auditory and the visual modalities even when it comes to selective attention.

P381 Event-related potentials and personality type in patients with multiple sclerosis

Objectives The clinical course of multiple sclerosis (MS) can vary significantly among patients and is affected by many factors. Among these, psychoaffective aspects, including the type of personality, have been recently gaining attention. The aim of our study was to investigate the parameters of event-related potentials (ERP) with regards to personality type in MS patients. Methods 30 relapsing-remitting MS patients (26 women and 4 men, mean age 34.9 years) and 26 healthy, age- and gender-matched controls were included in the study. All the patients were being treated with disease-modifying agents (interferon beta or glatiramer acetate) and presented with mild degree of disability (up to 3.0 in Expanded Disability Status Scale) All MS patients and controls underwent auditory ERP with the assessment of N200 and P300 components. D-type Scale (DS 14) was performed in the patients to determine the features of type D personality, characterized by social inhibition and negative affectivity. Relationships were searched between ERP parameters and DS 14 results, using v.10 of STATISTICA statistical software. Results P300 and N200 latencies were significantly longer ( p p R = 0.53, p R = −0.28, p Conclusions MS patients presented with abnormalities of ERP in comparison with the controls. ERP parameters showed significant relationships with features of D-type personality, including negative affectivity.

Event-related potential parameters related to typicality effects during category-based induction

Previous event-related potential (ERP) studies investigating the typicality effects during category-based reasoning were conducted during the deduction and induction phases by comparing typical and atypical conclusion categories, without property inference processes. In the present study, the ERP responses to both conclusion typicality effects (strengthening of the inference from “durian has the novel property X1” to “apple has the novel property X1” [a typical conclusion]was stronger than the inference from “durian has the novel property X1” to “Chinese date has the novel property X1 [an atypical conclusion], experiment 1) and premise typicality effects (strengthening of the inference from “apple has the novel property X1”[a typical premise]to “durian has the novel property X1” was stronger than the inference from “Chinese date has the novel property X1”[an atypical premise] to “durian has the novel property X1”, experiment 2) during category-based induction were measured by separately presenting the conclusion categories and conclusion properties. The results of both the experiments showed that, during the conclusion-category stage, typical conditions elicited larger P2 responses than atypical conditions, suggesting increased semantic feature activity in typical conditions. Additionally, atypical conditions elicited larger N400 responses than typical conditions, suggesting the increased cognitive effort related to semantic integration in atypical conditions than in typical conditions. During the conclusion-property stage, when participants accepted the inferences, both the experiments showed that typical conditions elicited larger P3b responses than atypical conditions, reflecting the higher degree of expected satisfaction during reasoning. Therefore, when the inferences were positive during category-based induction, N400 responses indexed the typicality effects during the conclusion-category stage, whereas P3b responses indexed the typicality effects during the conclusion-property stage.

Categorical ERP repetition effects for human and furniture items in 7‐month‐old infants

AbstractBehavioural and recent neural evidence indicates that young infants discriminate broad stimulus categories. However, little is known about the categorical perception of humans represented as full bodies with heads and their discrimination from inanimate objects. This study compares infants' brain processing of human and furniture pictures, probing infants' categorization skills with an event‐related potential (ERP) paradigm. Seven‐month‐old infants (n = 23) were tested in a rapid repetition ERP paradigm. Trials consisted of two consecutive stimuli: prime and target. Different ERP parameters (Nc, PSW) were compared across human and furniture items and for repeated and unrepeated categories. The PSW was consistently enhanced for unrepeated compared to repeated categories, thus indicating category discrimination. Nc amplitude was enhanced for furniture primes compared to human primes, but not for corresponding targets. In sum, these findings suggest that ERP rapid repetition studies are suitable for probing perceptual category discrimination in infancy. 7‐month‐olds discriminated between humans, presented as full body pictures, and furniture exemplars, but did not seem to prefer either of these categories.Highlights 7‐month‐olds' ability to categorize humans and furniture items was tested using rapid repetition ERPs. The PSW was enhanced for unrepeated categories, indicating broad categorization. The Nc, indicating neural attention, was not enhanced for humans compared to furniture items.

Cognitive event-related potentials in multiple sclerosis: Correlation with MRI and neuropsychological findings

BackgroundCognitive event-related potentials (ERPs) have been previously correlated with T2 lesion load (Τ2LL) in patients with multiple sclerosis (MS). It is currently unknown, however, whether ERPs also correlate with brain atrophy or the presence of T1 hypointense lesions (“black holes”) which reflect tissue destruction and axonal loss. The primary aim of the current study is to explore the effect of neuroradiological parameters such as brain atrophy, T1 and T2 lesion load on auditory ERPs in MS patients. In addition, we correlated cognitive impairment with neurophysiological (ERP) and neuroradiological (MRI) variables and investigated whether a combination of ERP and MRI parameters is capable of distinguishing patients suffering from secondary progressive (SP), primary progressive (PP) and relapsing-remitting (RR) MS. Materials and methodsThe study sample consisted of fifty nine MS patients (mean age±SD: 37.82±1.38 years; average disease duration: 6.76±5.3 years) and twenty six age-matched controls (mean age±SD: 41.42±15.39 years). The patients’ EDSS and NRS scores were 3.77±2.14 (range: 1–7.5) and 75.88±11.99 (range: 42–94) respectively. ERPs were recorded using the auditory “odd-ball” paradigm. T1 and T2 lesions were automatically segmented using an edge-finding tool and total lesion volumes were calculated. MRI measures of brain atrophy included third ventricle width (THIRDVW) and the ratio of mid-sagittal corpus callosum area to the mid-sagittal intracranial skull surface area (CC/MISS). Statistical analysis was performed using multiple regression, principal component (PCA) and discriminant analysis. ResultsT1 lesion load emerged as the most significant predictor of P300 and N200 latency. The rest of the endogenous ERPs parameters (P300 amplitude, N200 amplitude) were not significantly correlated with the MRI variables. PCA of pooled neuroradiological and neurophysiological markers suggested that four components accounted for 64.6% of the total variability. Discriminant analysis based on ERP & MRI markers classified correctly 79.63% of patients in RR, PP and SP subgroups. ConclusionT1 lesion load is the most significant MRI correlate of auditory ERPs in MS patients. Importantly, ERPs in combination with MRI variables can be usefully employed for distinguishing patients with different subtypes of MS.

Rubberband Effect in Temporal Control of Mismatch Negativity.

Mismatch negativity (MMN) is a difference event-related potential (ERP) wave reflecting the brain’s automatic reaction to deviant sensory stimuli, and it has been proven to be a useful tool in research on cognitive functions or clinical disorders. In most MMN studies, amplitude, peak latency, or the integral of the responses, in rare cases also the slopes of the responses, have been employed as parameters of the ERP responses for quantitative analyses. However, little is known about correlations between these parameters. To better understand the relations between different ERP parameters, we extracted and correlated several different parameters characterizing the MMN waves. We found an unexpected correlation which gives new insight into the temporal control of MMN: response amplitudes are positively correlated with downside slopes, whereas barely correlated with upside slopes. This result suggests an efficient feedback mechanism for the MMN to return to the baseline within a predefined time window, contradicting an exponential decay function as one might expect. As a metaphor we suggest a rubberband effect for the MMN responses, i.e., the larger the distance of the response from neural equilibrium, the stronger the return force to equilibrium.

Effects of escitalopram with a Chinese traditional compound Jiuweizhenxin-keli on mismatch negativity and P50 in patients with major depressive disorders

ObjectiveThe objective of this study was to investigate the therapeutic effects of escitalopram in conjunction with Jiuweizhenxin-keli on neuroelectrophysiology in patients with major depressive disorders (MDD).Patients and methodsPatients with depressive episode of MDD according to the criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, were randomly assigned to Esc group (30 patients) receiving escitalopram treatment and JK group (30 patients) treated with a combination of escitalopram and Jiuweizhenxin-keli. The healthy control (HC) group (30 persons with normal health condition) served as control. All groups were subject to examination of 24-item Hamilton Depression Rating Scale and Hamilton Anxiety Scale, mismatch negativity (MMN), and sensory gating potential P50 (SG-P50) of event-related potentials. Data were collected at three different time points: baseline (before treatment) and week 2 and week 6 post treatment.ResultsAt baseline, all electrophysiological parameters of patients with MDD were significantly higher than those of HCs. After treatment, in the Esc group, MMN latency, S2-P50 amplitude, and S2-P50/S1-P50 amplitude ratio decreased; however, the decrements were not statistically significant compared to either baseline or the HC group. Also, no significant changes were observed in the percentage of individuals whose S2-P50/S1-P50 ≥0.5 in the Esc group. On the other hand, in the JK group after a 6-week treatment, MMN latency (206.35±32.14 ms) was significantly shorter than that of the Esc group (219.57±36.51 ms), S2-P50 amplitude (7.27±4.85 μV) reduced significantly compared with the baseline level (10.21±4.10 μV), the percentage of individuals whose S2-P50/S1-P50 ≥0.5 in the JK group greatly decreased and this was not significantly different compared to that of the HC group (P≥0.05).ConclusionNeuroplasticity of patients with MDD is apparently disturbed, characterized by aberrant MMN latency and SG-P50-related event-related potential parameters. A combination of escitalopram and Jiuweizhenxin-keli treatment can markedly restore these neuroelectrophysiological features, and thus, could be a novel therapeutic solution for improving the impaired neuroplasticity of MDD patients.

Cognitive performance, fatigue and event-related potentials in patients with clinically isolated syndrome

ObjectivesCognitive impairment and fatigue are regarded as important aspects of multiple sclerosis. The aim of this study was to evaluate cognitive performance, the level of fatigue and parameters of event-related potentials (ERP) in patients diagnosed with clinically isolated syndrome (CIS). Patients and methodsThe study comprised 44 patients with CIS and 45 healthy controls. Cognitive performance was assessed using the Brief Repeatable Battery of Neuropsychological Tests (BRBNT), fatigue - using the Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS). Auditory ERP were performed and the parameters of N200 and P300 components were analyzed. Neuropsychological and electrophysiological measures were referred to clinical and radiological features of the disease activity. ResultsForty five% of patients failed in at least one test from BRBNT, mainly within the domains of memory and attention. In 18% of patients FSS corresponded with moderate or severe fatigue. The mean latency of N200 and P300 was significantly longer and amplitude of P300 was lower in those patients with CIS than in the controls. Significant correlations were found between the results of MFIS and tests evaluating verbal memory and attention, as well as between N200 latency and results of tests for verbal memory. ConclusionsCognitive performance and fatigue deserve attention from the earliest clinical stage of MS. Abnormalities of event-related potentials in CIS suggest early impact of the disease on functional neural networks.

Effect of Normal Aging and of Mild Cognitive Impairment on Event-Related Potentials to a Stroop Color-Word Task.

Event-related potentials (ERPs) were recorded from 84 adults (51 to 87 years old) with the aim of exploring the effects of aging (middle-aged and older groups) and cognitive status (healthy or with amnestic mild cognitive impairment, aMCI) on the neural functioning associated with stimulus and response processing in a Stroop color-word task. An interference (or Stroop) effect was observed in the Reaction Time (RT), and the RT and number of errors results were consistent with the age-related decline in performance. Cognitive status did not affect the behavioral performance of the task, but age and cognitive status affected several ERP parameters. Aging was associated with a) slowing of the neural processing of the stimuli (P150, N2, and P3b latencies were longer), b) greater activation of the motor cortex for response preparation (LRP-R amplitude was larger), and c) use of more neural resources for cognitive control of stimuli (N2 amplitude was larger to the congruent and incongruent stimuli than to the colored X-strings, in the older group). Independent of age, aMCI dedicated more neural resources to processing the irrelevant dimension of the stimulus (they showed a greater difference than the control participants between the P3b amplitude to the colored X-strings and to the congruent/incongruent stimuli) and showed a deficit in the selection and preparation of the motor response (with smaller LRP-S and LRP-R amplitudes). Furthermore, the middle-aged aMCI participants evaluated and classified both congruent and incongruent stimuli more slowly (they showed longer P3b latencies) relative to middle-aged controls.

Effects of unconscious perception of acoustic stimuli on event-related potential parameters

The influence of unconscious perception of acoustic stimuli on the event-related electrical activity of the human brain was determined. For this purpose, the event-related potentials (ERPs) evoked by the acoustic stimuli presented in the unconscious priming paradigm were recorded in the subjects. Monosyllabic Russian words with a single vowel letter substitution (‘sad’ and ‘sud’) and the pseudoword ‘sid’ were chosen as stimuli for priming. It was found that repetition and alternative priming significantly and similarly affected the ERP component amplitude with 200 ms latency after target application in the central, parietal, and temporal leads. Under the conditions of alternative priming, the direction of the potential amplitude modification with a latency of 400 ms was altered for the word and pseudoword targets. Alternative priming significantly increased the amplitude of this component with a pseudoword target and decreased it if the word existing in the language was used as a target stimulus. Since none of the participants was able to distinguish the applied prime stimuli, the changes in the ERP amplitude parameters might have been evoked by unconscious perception of acoustic stimuli by the subjects. The ERP amplitude dynamics revealed in this study demonstrates the possibility that subliminal acoustic stimuli modulate the electrical activity evoked by verbal acoustic stimulation.

Event-related potential parameters of category and property violations during semantic category-based induction

Previous studies have failed to clarify the event-related potentials (ERPs) that occur in response to categorization and property inferences during category-based induction. The present study examined ERP differences among acceptable-induction conclusions, unrelated-category conclusions, and unrelated-property conclusions to dissociate categorization and property-inference processing during category-based induction. The results showed that: (a) conclusions with categories that were unrelated to the premise evoked greater frontal N2 amplitudes, smaller P3b amplitudes, and greater N400 amplitudes, compared to conclusions with categories that were logically related to the premise; and (b) conclusions with unrelated properties evoked larger late positive components (LPCs) during the 700–800ms time interval compared to conclusions with related properties. These results suggest that the N2–P3b–N400 effects reflect categorization violations, while the LPCs are related to property violations during category-based induction, therefore, the ERP responses to category-related and property-related processes are dissociated respectively during category-based induction.

Neural Correlates Related to Anxiety in Attentional Inhibition Control: an ERP Study

We investigated the effect of anxiety on attentional inhibitory control using event-related potentials (ERPs) and measuring the response time. Nineteen participants performed a multi-source interference task; three-digit numbers and emotional faces were used as visual stimuli. The P100 and P300 ERPcomponents and response time values were used to evaluate whether ERP parameters and behavioral responses are associated with increased anxiety. Higher anxiety was associated with a longer latency and reduced amplitude of the P300 component at F3, whereas higher anxiety was associated with a shorter latency and higher amplitude of P300 at F4. The longer P300 latency at F3 was especially related to the response time to the target number with negative-expression faces as distracters.

P485: Event-related potentials in patients with primary Sjögren’s syndrome

s of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339 S179 Abstract P484 – Figure 2P484 – Figure 2 neuropathy with a high variable clinical course and outcome. Despite immunotherapy up to 20% of patients remain severely disabled and mortality in the first year is approximately 4%. Aim of this study is to perform an epidemiological analysis of clinical and electrophysiological features of patients admitted in our ward for GBS in last ten years; to test the incidence of different GBS subtypes and their clinical and electrophysiological evolution; to test on our sample the prognostic value of variables known in literature and we suggested integration with new prognostic markers. We collected data prospectively from 89 patients regarding: demographic features, previous infections, clinical manifestations, kind of therapy received, motor deficit and disability (evaluated respectively with MRC sumscore and GBS disability score (GBSDS)). We measured dosage of protein in the cerebrospinal fluid (CSF). Serial nerve conduction studies (NCS) were performed. Differences between groups were compared by Fisher’s exact test. Potential prognostic factors were tested in uni and multivariable logistic analysis and was estimated by regression analysis. 19% of GBS were acute motor axonal neuropathy (AMAN) and showed more severe prognosis. High age was predictive of poor prognosis in acute inflammatory demyelinating neuropathy (AIDP) but not in AMAN. High GBSDS at nadir and cranial nerves involvement were predictive of being enable to run at 1 year. Conduction block did not have a significant distribution in GBS subtypes and showed no correlation with clinical outcome. In NCS performed between 30 and 90 days from the clinical onset, a pathological distal cMAP duration (DcMAPD) represented a distinctive marker of primary demyelinating pathophysiological mechanism, in our sample of GBS. The endurance of pathological DcMAPD showed a predictive value on long term disability in AIDP. This study confirms the key-role of serial NCS for a proper diagnosis of GBS subtypes. Further clinical-electrophysiological studies are necessary to define more inclusive work-up in GBS enabling forecasting of the patients with poorest long term outcome.

Effects of extremely low-frequency electric fields at different intensities and exposure durations on mismatch negativity

The effects of extremely low-frequency electric fields (ELF-EFs, 3–300Hz) on lipid peroxidation levels and antioxidant enzyme activities have been shown in many tissues and plasma after exposure to 50-Hz alternating current (AC) electric fields. However, similar studies investigating brain lipid peroxidation status are limited. Moreover and as far as we know, no study has been conducted to examine mismatch negativity (MMN) response in rats following exposure to a 50-Hz AC electric field. Therefore, the purpose of the study was to investigate different intensities and exposure durations of ELF-EFs on MMN component of event-related potentials (ERPs) as well as apoptosis and oxidative brain damage in rats. Ninety male rats, aged 3months were used in our study. A total of six groups, composed of 15 animals each, was formed as follows: sham-exposed rats for 2weeks (C2), sham-exposed rats for 4weeks (C4), rats exposed to 12-kV/m and 18-kV/m electric fields for 2weeks (E12-2 and E18-2), rats exposed to 12- and 18-kV/m electric fields for 4weeks (E12-4 and E18-4). At the end of the experimental period, MMN responses were recorded in urethane-anesthetized rats by electrodes positioned stereotaxically to the surface of the dura. After MMN recordings, animals were killed by exsanguination and their brain tissues were removed for 4-hydroxy-2-nonenal (4-HNE), protein carbonyl and TUNEL analysis. In the current study, different change patterns in ERP parameters were observed dependent on the intensity and exposure duration of ELF-EFs. There were differences in the amplitudes of ERP between the responses to the standard and the deviant tones in all groups. When peak-to-peak amplitude of the difference curves was evaluated, MMN amplitude was significantly decreased in the E18-4 group compared with the C4 group. Additionally, the amount of 4-HNE was increased in all experimental groups compared with the control group. Consequently, it could be concluded that electric field decreased MMN amplitudes possibly induced by lipid peroxidation.

Correlation of Cerebral Blood Flow Velocities and Event-related Potentials in Patients with MS

Objective: Studies on the relationship between cerebral blood flow velocities and event related potential (ERP) changes in non-dementia multiple sclerosis (MS) are completely lacking. The aim of the present study was to evaluate the association between cerebral blood flow velocities and ERP parameters in MS patients. Methods: 30 patients (8 male, 22 female,) with a mean age of 37 ± 8 years (range: 21-56) with a diagnosis of relapsing remitting MS according to Mc Donald’s criteria were included. Their mean EDSS score was 1.8 ± 1.7 (range: 0-5.5) and mean duration of disease was 70 ± 64 (range: 3-228) months. The patients were subdivided according to their mean disease duration. The group with the shorter disease duration comprised 15 MS patients who had been diagnosed with MS for less than 5 years(MS-short), and the group with the longer duration comprised 15 patients with disease durations exceeding 5 years(MS-long) Results: In the MS patients, the N200 potentials recorded from the frontal, central, and parietal regions were prolonged relative to the controls and the differences were significant The P300 latencies recorded from the frontal, central and parietal regions were significantly longer in patients with disease durations exceeding 5 years. The mean middle cerebral artery (MCA) blood flow velocities did not differ from those of normal controls. Conclusion: Although there was a negative correlation between MCA velocity and frontal and parietal N100 latencies, there was no clear correlation between MCA blood flow velocity and ERP parameters. An important finding of this study is a positive correlation between MCA blood flow velocity and Mini Mental State Examination scores. This is the first study to evaluate the relationship between ERP and cerebral blood flow velocity using transcranial Doppler ultrasound. No definite relationship was shown.

BOLD response to deviant face detection informed by P300 event-related potential parameters: A simultaneous ERP–fMRI study

Faces are multi-dimensional stimuli conveying parallel information about identity and emotion. Although event-related potential (ERP) studies have disclosed a P300 component in oddball responses to both deviant identity and emotional target faces, it is hypothesized that partially different neural processes should subtend emotion vs. identity within the core network of face processing. In the present study, we used simultaneous ERP-fMRI recordings and ERP-informed analysis of functional magnetic resonance imaging (fMRI) data to evidence the specific neural networks underlying P300 generation in response to different deviant emotional vs. identity faces. 18 participants were scanned during a visual oddball task in which they had to detect 3 types of deviant faces representing a change in emotion-fear or happiness-or in identity, within a series of frequent neutral ones. Amplitude and latency parameters of the P300 component, recorded for each type of deviant faces, were used to constrain fMRI analyses. Analysis of fMRI data informed by single-trial parameters of the P300 component disclosed specific activation patterns for fearful, happy and identity deviant faces. For fearful faces, P300 amplitudes were associated with BOLD changes in the left fusiform gyrus whereas latencies were linked to left superior orbito-frontal and right fusiform activations. P300 amplitude modulations for happy deviant faces involved the left posterior cingulate gyrus and right parahippocampal regions whereas P300 latencies related to the right insula and left caudate regions. Finally, identity deviant faces were associated with widespread activities involving cortical and subcortical regions when P300 amplitudes were considered, and P300 latencies were associated with activity in right hippocampal/parahippocampal regions. Our results suggest the existence of differential cerebral functional processes involved in the responses to deviant face stimuli, depending on the quality of the deviance (fear vs. happiness vs. identity).

Stability of Auditory Discrimination and Novelty Processing in Physiological Aging

Complex higher-order cognitive functions and their possible changes with aging are mandatory objectives of cognitive neuroscience. Event-related potentials (ERPs) allow investigators to probe the earliest stages of information processing. N100, Mismatch negativity (MMN) and P3a are auditory ERP components that reflect automatic sensory discrimination. The aim of the present study was to determine if N100, MMN and P3a parameters are stable in healthy aged subjects, compared to those of normal young adults. Normal young adults and older participants were assessed using standardized cognitive functional instruments and their ERPs were obtained with an auditory stimulation at two different interstimulus intervals, during a passive paradigm. All individuals were within the normal range on cognitive tests. No significant differences were found for any ERP parameters obtained from the two age groups. This study shows that aging is characterized by a stability of the auditory discrimination and novelty processing. This is important for the arrangement of normative for the detection of subtle preclinical changes due to abnormal brain aging.

Stability of auditory discrimination and novelty processing in physiological aging.

Complex higher-order cognitive functions and their possible changes with aging are mandatory objectives of cognitive neuroscience. Event-related potentials (ERPs) allow investigators to probe the earliest stages of information processing. N100, Mismatch negativity (MMN) and P3a are auditory ERP components that reflect automatic sensory discrimination. The aim of the present study was to determine if N100, MMN and P3a parameters are stable in healthy aged subjects, compared to those of normal young adults. Normal young adults and older participants were assessed using standardized cognitive functional instruments and their ERPs were obtained with an auditory stimulation at two different interstimulus intervals, during a passive paradigm. All individuals were within the normal range on cognitive tests. No significant differences were found for any ERP parameters obtained from the two age groups. This study shows that aging is characterized by a stability of the auditory discrimination and novelty processing. This is important for the arrangement of normative for the detection of subtle preclinical changes due to abnormal brain aging.