Event-related Potential Recordings Research Articles

Separating normosmic and anosmic patients based on entropy evaluation of olfactory event-related potentials

ObjectiveMethods based on electroencephalography (EEG) are used to evaluate brain responses to odors which is challenging due to the relatively low signal-to-noise ratio. This is especially difficult in patients with olfactory loss. In the present study, we aim to establish a method to separate functionally anosmic and normosmic individuals by means of recordings of olfactory event-related potentials (OERP) using an automated tool. Therefore, Shannon entropy was adopted to examine the complexity of the averaged electrophysiological responses. MethodsA total of 102 participants received 60 rose-like odorous stimuli at an inter-stimulus interval of 10 s. Olfactory-related brain activity was investigated within three time-windows of equal length; pre-, during-, and post-stimulus. ResultsBased on entropy analysis, patients were correctly diagnosed for anosmia with a 75% success rate. ConclusionThis novel approach can be expected to help clinicians to identify patients with anosmia or patients with early symptoms of neurodegenerative disorders. SignificanceThere is no automated diagnostic tool for anosmic and normosmic patients using OERP. However, detectability of OERP in patients with functional anosmia has been reported to be in the range of 50%.

On the Neurophysiological Mechanisms Underlying the Adaptability to Varying Cognitive Control Demands.

Cognitive control processes are advantageous when routines would not lead to the desired outcome, but this can be ill-advised when automated behavior is advantageous. The aim of this study was to identify neural dynamics related to the ability to adapt to different cognitive control demands – a process that has been referred to as ‘metacontrol.’ A sample of N = 227 healthy subjects that was split in a ‘high’ and ‘low adaptability’ group based on the behavioral performance in a task with varying control demands. To examine the neurophysiological mechanisms, we combined event-related potential (ERP) recordings with source localization and machine learning approaches. The results show that individuals who are better at strategically adapting to different cognitive control demands benefit from automatizing their response processes in situations where little cognitive control is needed. On a neurophysiological level, neither perceptual/attentional selection processes nor conflict monitoring processes paralleled the behavioral data, although the latter showed a descriptive trend. Behavioral differences in metacontrol abilities were only significantly mirrored by the modulation of response-locked P3 amplitudes, which were accompanied by activation differences in insula (BA13) and middle frontal gyrus (BA9). The machine learning result corroborated this by identifying a predictive/classification feature near the peak of the response-locked P3, which arose from the anterior cingulate cortex (BA24; BA33). In short, we found that metacontrol is associated to the ability to manage response selection processes, especially the ability to effectively downregulate cognitive control under low cognitive control requirements, rather than the ability to upregulate cognitive control.

The organization of words and environmental sounds in the second year: Behavioral and electrophysiological evidence.

The majority of research examining early auditory-semantic processing and organization is based on studies of meaningful relations between words and referents. However, a thorough investigation into the fundamental relation between acoustic signals and meaning requires an understanding of how meaning is associated with both lexical and non-lexical sounds. Indeed, it is unknown how meaningful auditory information that is not lexical (e.g., environmental sounds) is processed and organized in the young brain. To capture the structure of semantic organization for words and environmental sounds, we record event-related potentials as 20-month-olds view images of common nouns (e.g., dog) while hearing words or environmental sounds that match the picture (e.g., "dog" or barking), that are within-category violations (e.g., "cat" or meowing), or that are between-category violations (e.g., "pen" or scribbling). Results show both words and environmental sounds exhibit larger negative amplitudes to between-category violations relative to matches. Unlike words, which show a greater negative response early and consistently to within-category violations, such an effect for environmental sounds occurs late in semantic processing. Thus, as in adults, the young brain represents semantic relations between words and between environmental sounds, though it more readily differentiates semantically similar words compared to environmental sounds.

Differences in working memory as a function of physical activity in children.

Given previous research examining the relationship between physical activity (PA) and working memory in children has not taken into account of potentially confounders, this study specifically controlled for the effects of intelligence and fitness-related factors (i.e., aerobic and motor fitness) on this relationship. Thirty-two children were assigned to either the higher PA group (HP) (n = 16) or lower PA group (LP) (n = 16) based on their amount of PA as measured by an accelerometer. Working memory was measured by the delayed-matching test, with concurrent recordings of event-related potentials including the P3 and the positive slow wave (PSW) components. Data analysis controlling for the effects of potential confounders found that the HP group had higher response accuracy in both task conditions relative to the LP group. For reaction times (RT), the HP group showed shorter RT than the LP group in the delayed condition. Furthermore, the HP group had similar P3 amplitudes across task conditions, whereas amplitudes in the delayed condition were smaller than that in the non-delayed condition in the LP group. In addition, the HP group also showed larger PSW amplitudes than the LP group. Supplementary partial correlations analysis indicated negative correlations between levels of PA with RT in both task conditions, and positive correlations with P3 amplitude and PSW amplitude in the delayed condition. Children with higher levels of PA, while controlling for individual differences in intelligence and fitness-related factors, have better working memory as assessed by both behavioral and neuroelectric measures. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Selective Prefrontal Disinhibition in a Roving Auditory Oddball Paradigm Under N-Methyl-D-Aspartate Receptor Blockade

BackgroundDisturbances in N-methyl-D-aspartate receptors (NMDARs)—as implicated in patients with schizophrenia—can cause regionally specific electrophysiological effects. Both animal models of NMDAR blockade and clinical studies in patients with schizophrenia have suggested that behavioral phenotypes are associated with reduction in inhibition within the frontal cortex. MethodsHere we investigate event-related potentials to a roving auditory oddball paradigm under ketamine in healthy human volunteers (N= 18; double-blind, placebo-controlled, crossover design). Using recent advances in Bayesian modeling of group effects in dynamic causal modeling, we fit biophysically plausible network models of the auditory processing hierarchy to whole-scalp event-related potential recordings. This allowed us to identify regionally specific effects of ketamine in a distributed network of interacting cortical sources. ResultsWe show that the effect of ketamine is best explained as a selective change in intrinsic inhibition, with a pronounced ketamine-induced reduction of inhibitory interneuron connectivity in frontal sources, compared with temporal sources. Simulations of these changes in an integrated microcircuit model shows that they are associated with a reduction in superficial pyramidal cell activity that can explain drug effects observed in the event-related potential. ConclusionsThese results are consistent with findings from invasive recordings in animal models exposed to NMDAR blockers, and provide evidence that inhibitory interneuron–specific NMDAR dysfunction may be sufficient to explain electrophysiological abnormalities induced by NMDAR blockade in human subjects.

Email Overload? Brain and Behavioral Responses to Common Messaging Alerts Are Heightened for Email Alerts and Are Associated With Job Involvement.

We tested brain and behavioral responses to two common messaging alerts (Outlook and Android whistle) using an oddball paradigm, where participants had to detect the two alerts among a background of white noise and occasional matched, distractor stimuli. Twenty-nine participants were tested using a behavioral target detection task and a subset of 14 were tested both with event-related potential (ERP) and behavioral oddball detection. For the ERP recordings, participants were instructed to attend to a distractor DVD in one condition and in the other, to actively attend to the stimuli. We measured mismatch negativity (MMN) and P3a components and questionnaire responses to job involvement, rumination and work-life balance. There were significantly larger MMN responses to target alert signals, but only in the ignore condition. In both ignore and attend conditions, MMN was larger for the Android stimuli, probably as a result of the larger physical discriminability for the Android tone. On the other hand, there was a significant P3a for Outlook tones, but not for Android tones in the ignore condition. Neither alert showed significant P3a activity within the attend condition, but instead later frontal positivity, which was larger for the Outlook alert (in comparison to its matched distractor) and this effect was not seen for the Android tones. This was despite the Outlook alert being less perceptually discriminable compared to the Android alert. These findings suggest that the indices of attentional processing are more affected by the significance of the alert than the physical qualities. These effects were coupled with the finding that the faster reaction times to the Outlook sounds were correlated with greater job involvement. These data suggest that work-related messages might signal greater attentional switch and effort which in turn may feed into greater job involvement.

Dissociable functional activities of cortical theta and beta oscillations in the lateral prefrontal cortex during intertemporal choice

The lateral prefrontal cortex (LPFC) plays an important role in the neural networks involved in intertemporal choice. However, little is known about how the neural oscillation of LPFC functions during intertemporal choice, owing to the technical limitations of functional magnetic resonance imaging and event-related brain potential recordings. Electrocorticography (ECoG) is a novel neuroimaging technique that has high spatial and temporal resolution. In this study, we used ECoG and projected the ECoG data onto individual brain spaces to investigate human intracranial cortex activity and how neural oscillations of the LPFC impact intertemporal choice. We found that neural activity of theta oscillation was significantly higher during impulsive decisions, while beta oscillation activity was significantly higher during non-impulsive ones. Our findings suggest a functional dissociation between cortical theta and beta oscillations during decision-making processes involved in intertemporal choice, and that decision outcomes may be determined by LPFC modulation, which involves neural oscillations at different frequencies.

Inhibition and attentional control in pedophilic child sexual offenders – An event-related potential study

ObjectiveImpaired response inhibition might play a role in child sexual offences. Recording of event-related potentials (ERPs) can help to clarify whether child sexual offenders (CSOs) show an altered processing of stop signals and commission errors. MethodsIn the current ERP study, we investigated these processes in a Go/Nogo task on two groups of CSOs, pedophilic contact CSOs and non-contact CSOs (child pornography offenders), as well as on non-offenders as controls. ResultsBehaviorally, CSOs showed a slight, but non-significant increase of the false alarm rate to Nogo cues, as compared to controls. The amplitudes of the ERP components N2 and P3 to Nogo cues followed by correctly withhold responses did not vary between CSOs and controls. The analysis of the ERPs to committed errors showed that the Ne amplitudes (reflecting error detection) did not differ between the groups either, whereas the Pe amplitudes (reflecting error evaluation and error awareness) were strongly diminished in CSOs. This diminishment was primarily found in contact CSOs. ConclusionsThe findings suggest that response inhibition, processing of stop signals, and error detection are not necessarily impaired in CSOs. However, CSOs appear to dedicate less cognitive resources to the evaluation of committed errors. SignificanceThis selective alteration could reflect a reduced sense of responsibility for misconduct in this offender group, which might contribute to their delinquent behavior.

Detecting Concealed Information with Fused Electroencephalography and Functional Near-infrared Spectroscopy

In this study, fused electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) techniques were utilized to examine the relationship between the ERP (event-related potential) component P300 and fNIRS hemodynamic signals for high-accuracy deception detection. During the performance of a modified concealed information test (CIT) task, a series of Chinese names were presented, which served as the target, irrelevant, or the probe stimuli for both the guilty and innocent groups. For participants in the guilty group, the probe stimulus was their individual name, whereas for the innocent group, the probe stimulus was one irrelevant name. In particular, data from concurrent fNIRS and ERP recordings were carefully inspected for participants from the two groups. Interestingly, we discovered that for the guilty group, the probe stimulus elicited significantly higher P300 amplitude at parietal site and also evoked significantly stronger oxyhemoglobin (HbO) concentration changes in the bilateral superior frontal gyrus and bilateral middle frontal gyrus than the irrelevant stimuli. However, this is not the case for the innocent group, in which participants exhibited no significant differences in both ERP and fNIRS measures between the probe and irrelevant stimuli. More importantly, our findings also demonstrated that the combined ERP and fNIRS feature was able to differentiate the guilty and innocent groups with enhanced sensitivity, in which AUC (the area under Receiver Operating Characteristic curve) is 0.94 for deception detection based on the combined indicator, much higher than that based on the ERP component P300 only (0.85) or HbO measure only (0.84).

The effect of a virtual reality learning environment on learners’ spatial ability

This study employed electroencephalography to record event-related potentials to investigate the difference in learning performance between learners with different levels of spatial ability in a traditional learning environment that utilizes presentation slides and a learning environment that incorporates virtual reality (VR). Thirty-two university students participated in the experiment. The N1 and P2 components were results that indicated selective attention at an early stage; their amplitudes were proportional to the cognitive loads. The experiment results revealed that the main effect of learning environment was significant. The N1 and P2 components had larger amplitudes and indicated higher cognitive loads in the presentation slides-based environment than in the VR-based environment. The main effect of spatial ability was also significant. The N1 and P2 amplitudes evoked in the high spatial ability (HSA) learners were smaller than those evoked in the low spatial ability (LSA) learners, indicating that the LSA learners possessed fewer cognitive resources and bore relatively high cognitive loads. The interaction effect of learning environment and spatial ability was significant. Larger P2 amplitude was observed in LSA learners in the presentation slides-based environment than in the VR-based environment, implying that VR facilitates the reduction of cognitive loads in LSA learners. The P2 amplitude detected in HSA learners did not show any significant difference in both learning environments, indicating that the VR-based learning environment did not enhance their learning. This result supports the ability-as-compensator hypothesis to a certain extent.

Neurophysiological Effects of Aging: A P200 ERP Study.

Age-related effects were studied in 14 younger (M = 34 years) and 14 (M = 47 years) older healthy participants. Event-related potential (ERP) recording was done using a 256-channel EEG system. Results indicated that ERP is affected by advanced age. There was a significant difference in P200 mean latency between the younger participants and older participants for the target (low-probability) stimuli, but no such significance was evident for the P200 mean latency during the presentation of the standard (high-probability) stimuli. As for the P200 mean peak amplitude, the results for the target (low-probability) stimuli did show a significant difference between the two age groups, while the results for the standard (high-probability) stimuli did not show any significant difference between the two age groups. The results of this study are explained in light of aging effects on attentional recruitment and frontal lobe intactness.

Altered perception-action binding modulates inhibitory control in Gilles de la Tourette syndrome.

Gilles de la Tourette Syndrome (GTS) is a multifaceted neuropsychiatric developmental disorder with onset in childhood or adolescence and frequent remissions in early adulthood. A rather new emerging concept of this syndrome suggests that it is a disorder of purposeful actions, in which sensory processes and their relation to motor responses (actions) play a particularly important role. Thus, this syndrome might be conceived as a condition of altered 'perception-action binding'. In the current study, we test this novel concept in the context of inhibitory control. We examined N=35 adolescent GTS patients and N=39 healthy controls in a Go/Nogo-task manipulating the complexity of sensory information triggering identical actions; i.e. to inhibit a motor response. This was combined with event-related potential recordings, EEG data decomposition and source localization. GTS patients showed worse performance compared to controls and larger performance differences when inhibitory control had to be exerted using unimodal visual compared to bimodal auditory-visual stimuli. This suggests increased binding between bimodal stimuli and responses leading to increased costs of switching between responses instructed by bimodal and those instructed by unimodal stimuli. The neurophysiological data showed that this was related to mechanisms mediating between stimulus evaluation and response selection; i.e. perception-action binding processes in the right inferior parietal cortex (BA40). Stimulus-action inhibition binding is stronger in GTS patients than healthy controls and affects inhibitory control corroborating the concept suggesting that GTS might be a condition of altered perception-action integration (binding); i.e. a disorder of purposeful actions.

An ERP study on metacognitive monitoring processes in children

Little is known about what exactly differentiates metacognitive processes from ordinary cognitive processes particularly early in development, and the underlying developmental aspects. To examine the time-course of metacognition, the present study investigated the neural underpinnings of judgments of learning (JoLs) and compared them with control judgments, using an event-related potentials (ERP) design. During ERP recording, children age seven to eight were presented with cue-target picture pairs and instructed to learn these pairs. After each pair, they either had to make a JoL (assess the likelihood of remembering the target when only presented with the cue) or a colour judgment (indicate whether the colour yellow had been present in one of the two pictures presented earlier). Results revealed a late slow wave divergence maximal pronounced from 550 ms to 950 ms post-stimulus that distinguished between JOLs and colour judgments. Over centro-parietal areas, JoLs showed a more negative going slow wave compared to the colour judgments, and this pattern was independent of performance. The results are in support of theories that assume a distinction between metacognitive and cognitive processes.

How face blurring affects body language processing of static gestures in women and men.

The role of facial coding in body language comprehension was investigated by event-related potential recordings in 31 participants viewing 800 photographs of gestures (iconic, deictic and emblematic), which could be congruent or incongruent with their caption. Facial information was obscured by blurring in half of the stimuli. The task consisted of evaluating picture/caption congruence. Quicker response times were observed in women than in men to congruent stimuli, and a cost for incongruent vs congruent stimuli was found only in men. Face obscuration did not affect accuracy in women as reflected by omission percentages, nor reduced their cognitive potentials, thus suggesting a better comprehension of face deprived pantomimes. N170 response (modulated by congruity and face presence) peaked later in men than in women. Late positivity was much larger for congruent stimuli in the female brain, regardless of face blurring. Face presence specifically activated the right superior temporal and fusiform gyri, cingulate cortex and insula, according to source reconstruction. These regions have been reported to be insufficiently activated in face-avoiding individuals with social deficits. Overall, the results corroborate the hypothesis that females might be more resistant to the lack of facial information or better at understanding body language in face-deprived social information.

Uncanny valley as a window into predictive processing in the social brain

Uncanny valley refers to humans' negative reaction to almost-but-not-quite-human agents. Theoretical work proposes prediction violation as an explanation for uncanny valley but no empirical work has directly tested it. Here, we provide evidence that supports this theory using event-related brain potential recordings from the human scalp. Human subjects were presented images and videos of three agents as EEG was recorded: a real human, a mechanical robot, and a realistic robot in between. The real human and the mechanical robot had congruent appearance and motion whereas the realistic robot had incongruent appearance and motion. We hypothesize that the appearance of the agent would provide a context to predict her movement, and accordingly the perception of the realistic robot would elicit an N400 effect indicating the violation of predictions, whereas the human and the mechanical robot would not. Our data confirmed this hypothesis suggesting that uncanny valley could be explained by violation of one's predictions about human norms when encountered with realistic but artificial human forms. Importantly, our results implicate that the mechanisms underlying perception of other individuals in our environment are predictive in nature.

Neural bases of sensorimotor adaptation in the vocal motor system.

The present study used event-related potential (ERP) recordings to investigate the neural mechanisms of sensorimotor adaptation in response to altered auditory feedback (AAF) during vocal production. 12 healthy speakers were tested under a vocal motor adaptation paradigm in which the fundamental frequency (F0) of their voice auditory feedback was pitch-shifted downward by one semi-tone (- 100 cents) during vowel vocalizations. Behavioral results revealed that subjects adapted to AAF by producing opposing (upward) responses to pitch-shift stimuli, and this adaptive behavior persisted after feedback alteration was removed (washout). We found that adaptation to AAF was accompanied by a significant increase in the amplitude of a parietal ERP activityelicited after the onset of vocalization. However, no such effect was observed for pre-motor ERPs elicited before vocalization onset. Moreover, we found that adaptive vocal responses were negatively correlated with ERPs over the parietal and positively correlated with those over the fronto-central areas after vocalization onset. These findings suggest that vocal motor adaptation is mediated by sensorimotor reprogramming of feedforward motor commands through incorporating auditory feedback, which is indexed by modulation of behavioral and ERP responses to AAF. We suggest that modulation of neural activities in the parietal cortex highlights its significance as a neural interface for sensorimotor integration and indicates its critical role in vocal motor adaptation. Our findings support the notion that the parietal mechanisms are involved in driving adaptive motor behavior to cope with unexpected changes in the sensory environment to accomplish communication goals during vocal production and motor control.

Evidence of impaired proactive control under positive affect

If it can be assumed that positive affect modulates cognitive control, the underlying mechanisms remain unclear. The main aim of this study was to investigate how positive affect influences proactive and reactive modes of control and to explore the temporal dynamic of this influence, in terms of its transient and/or sustained effects. We used the AX-continuous performance task, combined with event-related potentials (ERP) recording. The results showed that positive affect impaired proactive control. More specifically, response preparation was weaker, as highlighted by a decreased contingent negative variation (CNV), prior to the target. As a consequence, conflict detection, as reflected by the N2 component, was decreased under positive affect. The P3a, associated with conflict resolution, remained unaffected by positive emotion, suggesting a lack of reactive control modulation. These effects were diffuse and did not appear on a transient timescale, highlighting the importance of positive emotion's time course for how it influences cognitive control processes.

Saliency of Vowel Features in Neural Responses of Cochlear Implant Users.

Cochlear implants restore hearing in deaf individuals, but speech perception remains challenging. Poor discrimination of spectral components is thought to account for limitations of speech recognition in cochlear implant users. We investigated how combined variations of spectral components along two orthogonal dimensions can maximize neural discrimination between two vowels, as measured by mismatch negativity. Adult cochlear implant users and matched normal-hearing listeners underwent electroencephalographic event-related potentials recordings in an optimum-1 oddball paradigm. A standard /a/ vowel was delivered in an acoustic free field along with stimuli having a deviant fundamental frequency (+3 and +6 semitones), a deviant first formant making it a /i/ vowel or combined deviant fundamental frequency and first formant (+3 and +6 semitones /i/ vowels). Speech recognition was assessed with a word repetition task. An analysis of variance between both amplitude and latency of mismatch negativity elicited by each deviant vowel was performed. The strength of correlations between these parameters of mismatch negativity and speech recognition as well as participants' age was assessed. Amplitude of mismatch negativity was weaker in cochlear implant users but was maximized by variations of vowels' first formant. Latency of mismatch negativity was later in cochlear implant users and was particularly extended by variations of the fundamental frequency. Speech recognition correlated with parameters of mismatch negativity elicited by the specific variation of the first formant. This nonlinear effect of acoustic parameters on neural discrimination of vowels has implications for implant processor programming and aural rehabilitation.

Stereo viewing modulates three-dimensional shape processing during object recognition: A high-density ERP study.

The role of stereo disparity in the recognition of 3-dimensional (3D) object shape remains an unresolved issue for theoretical models of the human visual system. We examined this issue using high-density (128 channel) recordings of event-related potentials (ERPs). A recognition memory task was used in which observers were trained to recognize a subset of complex, multipart, 3D novel objects under conditions of either (bi-) monocular or stereo viewing. In a subsequent test phase they discriminated previously trained targets from untrained distractor objects that shared either local parts, 3D spatial configuration, or neither dimension, across both previously seen and novel viewpoints. The behavioral data showed a stereo advantage for target recognition at untrained viewpoints. ERPs showed early differential amplitude modulations to shape similarity defined by local part structure and global 3D spatial configuration. This occurred initially during an N1 component around 145–190 ms poststimulus onset, and then subsequently during an N2/P3 component around 260–385 ms poststimulus onset. For mono viewing, amplitude modulation during the N1 was greatest between targets and distracters with different local parts for trained views only. For stereo viewing, amplitude modulation during the N2/P3 was greatest between targets and distracters with different global 3D spatial configurations and generalized across trained and untrained views. The results show that image classification is modulated by stereo information about the local part, and global 3D spatial configuration of object shape. The findings challenge current theoretical models that do not attribute functional significance to stereo input during the computation of 3D object shape.

When repetitive mental sets increase cognitive flexibility in adolescent obsessive-compulsive disorder.

A major facet of obsessive-compulsive disorder (OCD) is cognitive inflexibility. However, sometimes, cognitive flexibility can be needed to reuse recently abandoned mental sets. Therefore, cognitive flexibility can in certain cases be useful to reinstate some form of rigid, repetitive behavior characterizing OCD. We test the counterintuitive hypothesis that under such circumstances, cognitive flexibility is better in OCD patients than controls. We examined N=20 adolescent OCD patients and N=22 controls in a backward inhibition (BI) paradigm. This was combined with event-related potential (ERP) recordings and source localization. The BI effect describes the cost of overcoming the inhibition of a recently abandoned mental set that is relevant again. Therefore, a strong BI effect is disadvantageous for cognitive flexibility. Compared to controls, OCD patients revealed a smaller backward inhibition effect. The EEG data revealed larger P1 amplitudes in backward inhibition trials in the OCD group, which was due to activation differences in the inferior frontal gyrus (BA47). The severity of clinical symptoms predicted these neurophysiological modulations. The power of the observed effects was about 95%. The study shows that cognitive flexibility can be better in OCD than controls. This may be the case insituations where superior abilities in the reactivation of repeating mental sets and difficulties to process new ones coincide. This may be accomplished by intensified inhibitory control mechanisms. The results challenge the view on OCD, since OCD is not generally associated with cognitive inflexibility.