Group Differences In Amplitude Research Articles

Attribution of intentions in autism spectrum disorder: A study of event-related potentials.

Autism spectrum disorder (ASD) is characterized by social cognition deficits, including difficulties inferring the intentions of others. Although deficits in attribution of intentions (AI) have been consistently replicated in ASD, their exact nature remains unexplored. Here we registered the electrophysiological correlates of a nonverbal social cognition task to investigate AI in autistic adults. Twenty-one male autistic adults and 30 male neurotypical volunteers performed a comic strips task depicting either intentional action (AI) or physical causality with or without human characters, while their electroencephalographic signal was recorded. Compared to neurotypical volunteers, autistic participants were significantly less accurate in correctly identifying congruence in the AI condition, but not in the physical causality conditions. In the AI condition a bilateral posterior positive event-related potential (ERP) occurred 200-400 ms post-stimulus (the ERP intention effect) in both groups. This waveform comprised a P200 and a P300 component, with the P200 component being larger for the AI condition in neurotypical volunteers but not in autistic individuals, who also showed a longer latency for this waveform. Group differences in amplitude of the ERP intention effect only became evident when we compared autistic participants to a subgroup of similarly performing neurotypical participants, suggesting that the atypical ERP waveform in ASD is an effect of group, rather than a marker of low-task performance. Together, these results suggest that the lower accuracy of the ASD group in the AI task may result from impaired early attentional processing and contextual integration of socially relevant cues. LAY SUMMARY: To understand why autistic people have difficulties in inferring others' intentions, we asked participants to judge the congruence of the endings of comic strips depicting either intentional actions (e.g., fetching a chair to reach for something) or situations solely following physical rules (e.g., an apple falling on someone's head), while their electrical brain activity was recorded. Autistic individuals had more difficulties in inferring intentions than neurotypical controls, which may reflect impaired attention and contextual integration of social cues.

Effects of age on loudness-dependent auditory ERPs in young autistic and typically-developing children

Limited research has investigated the development of auditory ERPs in young children, and particularly how stimulus intensity may affect these auditory ERPs. Previous research has also yielded inconsistent findings regarding differences in the development of auditory ERPs in autism and typical development. Furthermore, stimulus intensity may be of particular interest in autism insofar as autistic people may have atypical experiences of sound intensity (e.g., hyperacusis). Therefore, the present study examined associations between age and ERPs evoked by tones of differing intensities (50, 60, 70, and 80 dB SPL) in a large sample of young children (2–5 years) with and without an autism diagnosis. Correlations between age and P1 latencies were examined, while cluster-based permutation testing was used to examine associations between age and neural response amplitudes, as well as group differences in amplitude, over all electrode sites in the longer time window of 1–350 ms. Older autistic participants had faster P1 latencies, but these effects only attained significance over the right hemisphere in response to soft 50 dB sounds. Autistic participants had slower P1 responses to 80 dB sounds over the right hemisphere. Over the scalp regions associated with the later N2 response, more negative response amplitudes (that is, larger N2 responses) were observed in typically-developing than autistic participants. Furthermore, continuous associations between response amplitudes and age suggested that older typically-developing participants exhibited stronger N2 responses to all intensities, though this effect may have at least in part reflected the absence of small positive voltage deflections in the N2 latency window. Age was associated with amplitudes of responses to 50 dB through 70 dB sounds in autism, but in contrast to Typical Development (TD), little evidence of relationships between age and amplitudes in the N2 latency window was found in autism in the 80 dB condition. Although caution should be exercised in interpretation due to the cross-sectional nature of this study, these findings suggest that developmental changes in auditory responses may differ across diagnostic groups in a manner that depends on perceived loudness and/or stimulus intensity.

Behavioral and electrophysiological indices of inhibitory control in maltreated adolescents and nonmaltreated adolescents.

Early adverse experiences are believed to have a profound effect on inhibitory control and the underlying neural regions. In the current study, behavioral and event-related potential (ERP) data were collected during a go/no-go task from adolescents who were involved with the child welfare system due to child maltreatment (n = 129) and low-income, nonmaltreated adolescents (n = 102). The nonmaltreated adolescents were more accurate than the maltreated adolescents on the go/no-go task, particularly on the no-go trials. Paralleling the results with typically developing populations, the nonmaltreated adolescents displayed a more pronounced amplitude of the N2 during the no-go trials than during the go trials. However, the maltreated adolescents demonstrated a more pronounced amplitude of the N2 during the go trials than during the no-go trials. Furthermore, while the groups did not differ during the go trials, the nonmaltreated adolescents displayed a more negative amplitude of the N2 than the maltreated adolescents during no-go trials. In contrast, there was not a significant group difference in amplitude of the P3. Taken together, these results provide evidence that the early adverse experiences encountered by maltreated populations impact inhibitory control and the underlying neural activity in early adolescence.

Mild cognitive impairment in mild brain injury (MBI) patients: An event related potential (ERP) and neuropsychology study.

Objectives: To evaluate auditory cognitive function in mild brain injury (MBI) patients, which is important to determine for rehabilitation and improve quality of their life.
 Methods: Participants (n=19/group) were divided into group 1 (G1-control), group 2 (G2/1st test-MBI/within 7 days of road traffic accident-RTA) and group 3 (G3/2nd test-MBI/2-6 months after RTA). Event related potentials (ERPs) were conducted using a 128-sensor net; participants counted silently rare target tone stimuli and ignored standard tones. Several neuropsychology tests like Verbal fluency test (PAS), Wisconsin Card Sorting Test (WCST), Rey Auditory Verbal and Learning Test (RAVLTIM, RAVLTDR and RAVLTTS) and Beck Depression Inventory (BDI) were subsequently administered.
 Results: Sensory (P50, N100) and cognitive (P300) ERP components were analysed from ERP waveforms. There were no significant group differences in amplitudes or latencies for all components across sites except P300 component amplitudes at T6 location. P50, N100 and P300 ERP components exhibited non-significantly increased amplitudes in G2 and G3 compared with G1 at all sites; non-significantly shorter latencies were identified at various sites. At several locations, G3 evoked non-significantly increased amplitudes and longer latencies with shorter latencies to other sites compared with G2 in all components. The MBI (G3) group exhibited significantly increased WCST, RAVLTIM and RAVLTDR scores compared with G1.
 Conclusion: These findings indicate MBI patients may have mild auditory, cognitive and executive dysfunctions with good auditory memory. MBI was associated with mild depression.
 Bangladesh Journal of Medical Science Vol.18(3) 2019 p.557-566

First Language Attrition Induces Changes in Online Morphosyntactic Processing and Re‐Analysis: An ERP Study of Number Agreement in Complex Italian Sentences

First language (L1) attrition in adulthood offers new insight on neuroplasticity and the role of language experience in shaping neurocognitive responses to language. Attriters are multilinguals for whom advancing L2 proficiency comes at the cost of the L1, as they experience a shift in exposure and dominance (e.g., due to immigration). To date, the neurocognitive mechanisms underlying L1 attrition are largely unexplored. Using event‐related potentials (ERPs), we examined L1‐Italian grammatical processing in 24 attriters and 30 Italian native‐controls. We assessed whether (a) attriters differed from non‐attriting native speakers in their online detection and re‐analysis/repair of number agreement violations, and whether (b) differences in processing were modulated by L1‐proficiency. To test both local and non‐local agreement violations, we manipulated agreement between three inflected constituents and examined ERP responses on two of these (subject, verb, modifier). Our findings revealed group differences in amplitude, scalp distribution, and duration of LAN/N400 + P600 effects. We discuss these differences as reflecting influence of attriters’ L2‐English, as well as shallower online sentence repair processes than in non‐attriting native speakers. ERP responses were also predicted by L1‐Italian proficiency scores, with smaller N400/P600 amplitudes in lower proficiency individuals. Proficiency only modulated P600 amplitude between 650 and 900 ms, whereas the late P600 (beyond 900 ms) depended on group membership and amount of L1 exposure within attriters. Our study is the first to show qualitative and quantitative differences in ERP responses in attriters compared to non‐attriting native speakers. Our results also emphasize that proficiency predicts language processing profiles, even in native‐speakers, and that the P600 should not be considered a monolithic component.

Same clock, different time read-out: Spontaneous brain oscillations and their relationship to deficient coding of cognitive content

Neuronal oscillations provide an efficient means of communication, fostering functional neural states supporting action and reaction. High in the action hierarchy, cognitive abilities are severely compromised in neuropsychiatric disease such as schizophrenia. Current thinking highlights a clocking mechanism provided by the phase of an ongoing slow oscillation that offers a temporal frame for coding of perceptual and computational elements. Yet unclear is whether and how a dysregulated clocking mechanism accounts for diminished cognitive performance. Neuromagnetic oscillatory activity was related to cognitive performance assessed by the MATRICS Consensus Cognitive Battery in 58 healthy individuals (HC) and 46 schizophrenia patients (SZ). HC showed a correlation between gamma-band oscillations (>40Hz) and working memory performance. This relationship was disrupted in several ways in SZ. First, patients evidenced lower gamma power, poorer working memory performance, and no relationship between these measures. Second, the power spectra were dominated by ~10Hz alpha oscillations with no group differences in amplitude. However, analysis of phase-to-amplitude coupling (PAC) revealed exaggerated clocking of gamma activity by alpha phase in SZ, associated with poor working memory performance. Third, despite entrainment by the same 10Hz clock, gamma amplitude was abnormally distributed across the duty cycle in SZ, a potential consequence of compromised interneuron inhibition. Fourth, SZ showed over-engagement of a fronto-parietal network measured by gamma phase coherence, suggesting a brain state hindering cognitive output.Such an endogenous temporal organization may be a core dysfunction in SZ: a segregation/integration input imbalance fostering reduced cognitive performance and compromised behavioral output.

Localizing Functional Damage in the Neural Retina of Adolescents and Young Adults With Type 1 Diabetes

It is unknown which regions of the retina are most susceptible to damage by diabetes mellitus. We hypothesized that the standard and slow-flash (sf-) multifocal electroretinogram (mfERG) will localize retinal regions of greatest vulnerability. A total of 55 adolescents and young adults with type 1 diabetes and without diabetic retinopathy (DR) or with mild nonproliferative DR and 54 typically-developing, age-similar control participants underwent mfERG and sf-mfERG testing. The amplitude and implicit time of the first order response of the standard mfERG and of three multifocal oscillatory potentials (mfOPs) of the sf-mfERG were compared between groups at the level of hexagons, quadrants, and rings using separate mixed model ANOVAs. Spatial mapping of the P values from post hoc pairwise comparisons illustrated patterns of retinal dysfunction. Delays in mfERG implicit times were evident across the tested retinal areas in the diabetes group. Delays in sf-mfERG implicit times were found at different eccentricities for each mfOP in the diabetes group. The greatest delays were noted in the periphery for mfOP1, in the midperiphery for mfOP2, and in the macular region for mfOP3. There were no significant group differences in amplitude for the mfERG and sf-mfERG protocols. Delays in mfERG and sf-mfERG responses suggest that the inner retina is particularly vulnerable to diabetes. Localizing regions of early dysfunction will help guide future studies to examine early structural damage associated with DR.

Resting-State Functional Magnetic Resonance Imaging Activity and Connectivity and Cognitive Outcome in Traumatic Brain Injury

The study of brain activity and connectivity at rest provides a unique opportunity for the investigation of the brain substrates of cognitive outcome after traumatic axonal injury. This knowledge may contribute to improve clinical management and rehabilitation programs. To study functional magnetic resonance imaging abnormalities in signal amplitude and brain connectivity at rest and their relationship to cognitive outcome in patients with chronic and severe traumatic axonal injury. Observational study. University of Barcelona and Hospital Clinic de Barcelona, Barcelona, and Institut Guttmann-Neurorehabilitation Hospital, Badalona, Spain. Twenty patients with traumatic brain injury (TBI) were studied, along with 17 matched healthy volunteers. Resting-state functional magnetic resonance imaging and diffusion tensor imaging data were acquired. After exploring group differences in amplitude of low-frequency fluctuations (ALFF), we studied functional connectivity within the default mode network (DMN) by means of independent component analysis, followed by a dual regression approach and seed-based connectivity analyses. Finally, we performed probabilistic tractography between the frontal and posterior nodes of the DMN. Signal amplitude and functional connectivity during the resting state, tractography related to DMN, and the association between signal amplitudes and cognitive outcome. Patients had greater ALFF in frontal regions, which was correlated with cognitive performance. Within the DMN, patients showed increased connectivity in the frontal lobes. Seed-based connectivity analyses revealed augmented connectivity within surrounding areas of the frontal and left parietal nodes of the DMN. Fractional anisotropy of the cingulate tract was correlated with increased connectivity of the frontal node of the DMN in patients with TBI. Increased ALFF is related to better cognitive performance in chronic TBI. The loss of structural connectivity produced by damage to the cingulum tract explained the compensatory increases in functional connectivity within the frontal node of the DMN.

Electrocortical correlates of intra-subject variability in reaction times: Average and single-trial analyses

Intra-subject variability of reaction times (ISV), generally considered secondary to measures of central tendency, has become increasingly important for cognitive neuroscience. Event-related potential (ERP) research suggests an inverse relationship between ISV and P3b amplitude; however ERP methods’ reliance on averaged waveforms may be unsuitable for studying ISV due to potentially distorting effects of latency jitter. The present study investigates the neural bases of ISV through single-trial analysis of P3bs in groups with low and high ISV, using Infomax-rotated principal components analysis of ERP data. Results indicate that while latency jitter contributes to the reduced P3b amplitude seen in average ERPs of high ISV participants, group differences in amplitude survive the use of single-trial methods that are robust to such distortions. A decoupling of P3b and RT was also seen in the high ISV group. The results are discussed in the context of the P3b's dimensionality, and its possible catecholaminergic underpinnings.

Cardiovascular and muscle activity during chewing in whiplash-associated disorders (WAD)

Objective The present study aimed to elucidate possible physiological mechanisms behind impaired endurance during chewing as previously reported in WAD. We tested the hypothesis of a stronger autonomic reaction in WAD than in healthy subjects in response to dynamic loading of the jaw–neck motor system. Design Cardiovascular reactivity, muscle fatigue indicies of EMG, and perceptions of fatigue, exhaustion and pain were assessed during standardised chewing. Twenty-one WAD subjects and a gender/age matched control group participated. Baseline recordings were followed by two sessions of alternating unilateral chewing of a bolus of gum with each session followed by a rest period. Results More than half of the WAD subjects terminated the test prematurely due to exhaustion and pain. In line with our hypothesis the chewing evoked an increased autonomic response in WAD exhibited as a higher increase in heart rate as compared to controls. Furthermore, we saw consistently higher values of arterial blood pressure for WAD than for controls across all stages of the experiment. Masseter EMG did not indicate muscle fatigue nor were there group differences in amplitude and mean power frequency. Pain in the WAD group increased during the first session and remained increased, whereas no pain was reported for the controls. Conclusion More intense response to chewing in WAD might indicate pronounced vulnerability to dynamic loading of the jaw–neck motor system with increased autonomic reactivity to the test. Premature termination and autonomic involvement without EMG signs of muscle fatigue may indicate central mechanisms behind insufficient endurance during chewing.

The Impact of Early Institutional Rearing on the Ability to Discriminate Facial Expressions of Emotion: An Event‐Related Potential Study

Event-related potentials (ERPs), in response to 4 facial expressions of fear, angry, happy, and sad, were collected from 72 institutionalized children (IG), ages 7 to 32 months, in Bucharest, Romania, and compared with ERPs from 33 children, ages 8 to 32 months, who had never been institutionalized (NIG). The NIG and IG exhibited different patterns of responding in early latency components. Moreover, group differences in amplitude were evident across all components. Such differences may point to the role of early deprivation in disrupting the development of the neural circuitry involved in the recognition of facial expressions.

Recognition memory for unfamiliar faces does not differ for adult normal and dyslexic readers: an event-related brain potential study.

Differences in recognition memory for unfamiliar faces between adult developmental dyslexic (n=12) and normal readers (n=12) were studied by means of event-related brain potentials. Subjects performed a continuous face recognition task, in which 240 unfamiliar faces were presented on a computer screen, 100 of which were repetitions. For each face, subjects had to indicate whether it was presented before or not. Performance did not differ between normal and dyslexic readers. Old/repeated faces elicited more positive event-related potentials (ERPs) starting 250 ms poststimulus. These were analyzed in two time-windows encompassing the early (250-450 ms) and the late phase (450-750 ms) of the old/new effect. No group difference in amplitude or topography of the old/new effect emerged. However, ERPs for all faces were more positive for normal compared with those of dyslexic readers. These results show that a previously described recognition memory deficit for words in dyslexic readers is likely to be specific for verbal material.

Adrenalectomy reduces peripheral neural responses to gustatory stimuli in the rat.

In the rat, sodium need leads to an increase in sodium intake, which depends on salt taste sensitivity. The adrenalectomized rat, because of excessive body sodium loss, has been an important animal model for studying the physiological mechanisms underlying salt ingestion. In order to investigate the mediation by peripheral taste responsivity of changes in salt intake, multiunit responses of the chorda tympani nerve to various concentrations of sodium chloride, potassium chloride, lithium chloride, hydrochloric acid, and quinine hydrochloride were recorded from adrenalectomized and control rats. In order to control for a generalized decrease in sensory sensitivity, recordings from the auriculotemporal nerve to tactile stimulation of the pinna were also performed. There were no group differences in amplitude of the integrated neural responses to tactile stimulation. The largest decrease in gustatory responsivity occurred for suprathreshold concentrations of sodium chloride and lithium chloride. The data are discussed with reference to possible mechanisms underlying this neural alteration and to the role that reductions in salt taste responsivity play in mediating increases in salt intake.