Pz Electrode Research Articles

ERP recording shows subclinical differences in ADHD patients with and without Tuberous Sclerosis

To investigate whether among children and adolescents with attention deficit and hyperactivity disorder (ADHD) those with Tuberous Sclerosis (TS) show specific abnormalities of event-related potentials (ERPs). We recruited 10 ADHD patients: 5 with TS (mean age: 12.6 ± 4.3 years) and 5 without TS (mean age: 11.6 ± 3 years). By using an oddball paradigm, auditory mismatch negativity (MMN) and P3b responses were recorded from Fz and Pz electrodes, respectively. All patients were administered with cognitive, executive functioning, and behavioural questionnaires. No difference was found in cognitive and executive functioning between two groups. The P3b amplitude was significantly higher in TS patients (15.6 ± 9 μV) than in children and adolescents without TS (5.5 ± 2.7 μV) (p = 0.04). The MMN amplitude was higher in TS patients (19 ± 18 μV) than in those without TS (9 ± 6.9 μV), although the difference was not significant (p = 0.3). Our results show that P3 and MMN amplitudes are higher in ADHD patients with TS than in those without TS. This means that among children and adolescents with ADHD involuntary and mostly voluntary attention capabilities are better in those with TS. Since this difference was not found by neuropsychological testing, ERP recording can be useful to unravel subclinical differences between two groups.

Quantifying clinical improvements in patients with depression under the treatment of transcranial direct current stimulation using event related potentials.

The main goal of this study was to assess the changes in brain activities of patients with severe depression by applying transcranial direct current stimulation (tDCS) using event related potentials (ERPs). Seven patients (four males, with the mean age 34.85 ± 4.25) were asked to fill out Beck's depression questionnaires. EEG signals of subjects were recorded during Stroop test. This test entailed 360 stimulations, which included 120 congruent, 120 incongruent, and 120 neutral stimulations lasting for 12min. Subsequently, the dorso lateral prefrontal cortex in patients' left hemisphere was stimulated for six sessions using tDCS. At the end of tDCS treatment period, subjects filled out Beck's depression questionnaires again and EEG signal recordings were repeated simultaneously with Stroop test. Wavelet coefficients of EEG frequency bands in every stimulation type were extracted from ERP components. The changes in Beck score before and after tDCS were estimated using neural network model. The ERP results showed that the latency period of N400 component after applying tDCS decreased significantly. Moreover, a significant correlation was observed between percentage changes of congruent and incongruent accuracy and the increase in the average energy of wavelet coefficients in alpha band in Pz electrode with p = 0.0128, r = 0.9060 and p = 0.0037, r = 0.95, respectively. Additionally, the results of neural network model revealed that the changes in Beck score were estimated with an average error of 0.0519. Consequently, the improvement of depressed patients treated with tDCS could be estimated with good accuracy using average energy of wavelet coefficients in alpha band.

A Method for Simultaneous Evaluation of Muscular and Neural Prepulse Inhibition.

Prepulse inhibition (PPI) test has been widely used to evaluate sensorimotor gating. In humans, deficits in this mechanism are measured through the orbicularis muscle response using electromyography (EMG). Although this mechanism can be modulated by several brain structures and is impaired in some pathologies as schizophrenia and bipolar disorder, neural PPI evaluation is rarely performed in humans. Since eye blinks are a consequence of PPI stimulation, they strongly contaminate the electroencephalogram (EEG) signal. This paper describes a method to reduce muscular artifacts and enable neural PPI assessment through EEG in parallel to muscular PPI evaluation using EMG. Both types of signal were simultaneously recorded in 22 healthy subjects. PPI was evaluated by the acoustical startle response with EMG and by the P2-N1 event-related potential (ERP) using EEG in Fz, Cz, and Pz electrodes. In order to remove EEG artifacts, Independent Component Analysis (ICA) was performed using two methods. Firstly, visual inspection discarded components containing artifact characteristics as ocular and tonic muscle artifacts. The second method used visual inspection as gold standard to validate parameters in an automated component selection using the SASICA algorithm. As an outcome, EEG artifacts were effectively removed and equivalent neural PPI evaluation performance was obtained using both methods, with subjects exhibiting consistent neural as well as muscular PPI. This novel method improves PPI test, enabling neural gating mechanisms assessment within the latency of 100–200 ms, which is not evaluated by other sensory gating tests as P50 and mismatch negativity.

Topological reorganization of EEG functional network is associated with the severity and cognitive impairment in Alzheimer’s disease

Increasing interest is being directed to developing an objective marker that could be used for the assessment of symptom severity in Alzheimer’s disease (AD). This study assessed the utility of graph theory, an emerging topic in statistical physics, to identify the changes of brain topology in AD patients. A total of 108 AD patients were recruited and their scalp electroencephalogram (EEG) recordings were analyzed retrospectively. Weighted and undirected networks were constructed from EEG signals in different frequency bands and two fundamental measures of the whole-brain network, the average clustering coefficient (CC) and global efficiency (GE), were calculated. Meanwhile, the local structure of the network was investigated by nodal CC. We then examined the group differences of those measures and their association with cognitive assessments of AD patients. The results revealed a topological reorganization of alpha band network in AD patients. The nodal CCs from Fz and Pz electrodes seemed to be preserved in AD while those from frontal and central-parietal regions, such as F3, F4, C3, Cz, C4, P3 and P4, were affected significantly by the disease. Furthermore, significant correlations have been found between the global topological measures and the severity of AD, while the altered local structure was revealed to associate with cognitive impairment measured by the verbal fluency and digit-backward tests in AD patients. Overall, topological reorganization of the functional brain network is involved in the evolution of AD. Network measures, i.e., CC and GE, might serve as objective biomarkers for the evaluation of symptom severity in AD.

Electrophysiological and neuropsychological outcomes of severe obstructive sleep apnea: effects of hypoxemia on cognitive performance.

Obstructive sleep apnea syndrome (OSAS) is a sleep disorder characterized with upper airway obstructions. Some studies showed cognitive and electrophysiological changes in patients with OSAS; however, contradictory results were also reported. The purpose of the present study was twofold: (1) to investigate cognitive changes in severe OSAS patients by using neuropsychological tests and electrophysiological methods together, (2) to investigate influence of hypoxemia levels on cognition. Fifty-four severe OSAS patients and 34 age-, gender- and education matched healthy subjects were participated. OSAS patients were further divided into two subgroups according to minimum oxygen saturation levels. All participants underwent a detailed neuropsychological test battery. A classical visual oddball task was used to elicit ERP P300 and mean P300 amplitudes were measured from Fz, Cz and Pz electrode sites. OSAS patients showed reduced mean P300 amplitudes up to 43-51% on all electrode sites compared to healthy controls. Subgroup analysis revealed significant differences in neuropsychological test scores between healthy controls and high hypoxemia OSAS group, as well as between low and high hypoxemia groups. Moreover, both low and high hypoxemia OSAS groups had lower P300 amplitudes compared with healthy controls. P300 amplitudes showed a gradual decline in parallel with increasing hypoxemia severity; however, the difference between high and low hypoxemia OSAS groups did not reach significance. Moderate correlations were found between sleep parameters, neuropsychological test scores and P300 amplitudes. These results suggest that electrophysiological measures could be better indicators of cognitive changes than neuropsychological tests in OSAS, particularly in mildly affected patients.

Evaluation of electroencephalogram signals of the professional pianists during iconic memory and working memory tests using spectral coherence

Today, the neuroscience has growth in many aspects, and the effects of different factors on memory obtained many achievements. Several scientific and experimental studies evaluated effects of music on style and behavior of people; in this study, we evaluated memory between two groups of people, the professional pianists and normal people, through processing their electroencephalogram (EEG) signals using the coherence measure. In this study, EEG signals from 17 subjects during two memory tasks were recorded. After that, these signals were preprocessed, and spectral coherence connectivity measure between pair of electrodes was computed and then compared in the five frequency bands using independent t-test. This statistical analysis for working memory task showed significant differences in the temporal, central, and parietal lobes, especially in P7, P3, Pz, T8, C3, and C4 electrodes. As we know, these differences are related to learned skills and activities, words and sounds perception, and memory. Furthermore, for iconic memory task, significant differences were observed in the right hemisphere of these two groups. From this task, we can say professional pianists are different from normal people in the perception of images and creativity. Results of this study show the effects of music on human brain and memory.

Evaluation of electroencephalogram signals of the professional pianists during iconic memory and working memory tests using spectral coherence

Today, the neuroscience has growth in many aspects, and the effects of different factors on memory obtained many achievements. Several scientifc and experimental studies evaluated effects of music on style and behavior of people; in this study, we evaluated memory between two groups of people, the professional pianists and normal people, through processing their electroencephalogram (EEG) signals using the coherence measure. In this study, EEG signals from 17 subjects during two memory tasks were recorded. After that, these signals were preprocessed, and spectral coherence connectivity measure between pair of electrodes was computed and then compared in the fve frequency bands using independent t ‑test. Results of this statistical analysis for working memory task showed signifcant differences in the temporal, central, and parietal lobes, especially in P7, P3, Pz, T8, C3, and C4 electrodes. As we know, these differences are related to learned skills and activities, words and sounds perception, and memory. Furthermore, for iconic memory task, signifcant differences were observed in the right hemisphere of these two groups. From this task, we can say professional pianists are different from normal people in the perception of images and creativity. Results of this study show the effects of music on human brain and memory.

An acute bout of aerobic or strength exercise specifically modifies circulating exerkine levels and neurocognitive functions in elderly individuals with mild cognitive impairment.

Although exercise is an effective way to decrease the risk of developing Alzheimer's disease, the biological basis for such benefits from the different exercise modes remains elusive. The present study thus aimed (i) to investigate the effects of acute aerobic or resistance exercise on neurocognitive performances and molecular markers when performing a cognitive task involving executive functioning in older adults with amnestic mild cognitive impairment (aMCI), and (ii) to explore relationships of acute exercise-induced neurocognitive changes with changes in circulating levels of neuroprotective growth factors (e.g., BDNF, IGF-1, VEGF, and FGF-2, collectively termed ‘exerkines’), elicited by different acute exercise modes. Sixty-six older adults with aMCI were recruited and randomly assigned to an aerobic exercise (AE) group, a resistance exercise (RE) group, or a non-exercise-intervention (control) group. The behavioral [i.e., accuracy rate (AR) and reaction time (RT)] and electrophysiological [i.e., event-related potential (ERP) P3 latency and amplitude collected from the Fz, Cz, and Pz electrodes] indices were simultaneously measured when participants performed a Flanker task at baseline and after either an acute bout of 30 min of moderate-intensity AE, RE or a control period. Blood samples were taken at three time points, one at baseline (T1) and two after an acute exercise intervention (T2 and T3: before and after cognitive task test, respectively). The results showed that the acute AE and RE not only improved behavioral (i.e., RTs) performance but also increased the ERP P3 amplitudes in the older adults with aMCI. Serum FGF-2 levels did not change with acute aerobic or resistance exercise. However, an acute bout of aerobic exercise significantly increased serum levels of BDNF and IGF-1 and tended to increase serum levels of VEGF in elderly aMCI individuals. Acute resistance exercise increased only serum IGF-1 levels. However, the exercise-induced elevated levels of these molecular markers returned almost to baseline levels in T3 (about 20 min after acute exercise). In addition, changes in the levels of neurotrophic and angiogenic factors were not correlated with changes in RTs and P3 amplitudes. The present findings of changes in neuroprotective growth factors and neurocognitive performances through acute AE or RE suggest that molecular and neural prerequisites for exercise-dependent plasticity are preserved in elderly aMCI individuals. However, the distinct pattern of changes in circulating molecular biomarkers induced by two different exercise modes in aMCI elderly individuals and the potentially interactive mechanisms of the effects of BDNF, IGF-1, and VEGF on amyloid-β provide a basis for future long-term exercise intervention to investigate whether AE relative to RE might be more effective in prevention/treatment of an early stage neurodegenerative disease.

Demonstration of Early Cognitive Impairment in Parkinson's Disease with Visual P300 Responses.

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. Cognitive changes in PD are less observable than motor symptoms; thus, research on cognitive processes, which are known to be impaired from the early stages of PD, is minimal. The purpose of this study is to research the brain dynamics of cognitively normal PD patients and healthy elderly controls using event-related potentials (ERPs) and to evaluate their relationships with neuropsychological tests. Eighteen cognitively normal PD patients and 18 age-, gender-, and education-matched healthy controls were included in the study. Detailed neuropsychological tests were applied to all participants. Electroencephalography (EEG) was performed according to the international 10-20 system, and a classical visual oddball paradigm was used in the experiments. ERP responses in the 0.5 to 25 Hz frequency range were examined. P300 amplitude and latency values were measured from the F3, Fz, F4, C3, Cz, C4, P3, Pz, P4, O1, Oz, and O2 electrode sites. In addition, the correlations between P300 responses and neuropsychological test scores were analyzed. Significant differences were found between the P300 amplitudes of cognitively normal PD patients and healthy elderly controls [F(1,31)=9.265; p=0.005]. P300 amplitudes were significantly lower for PD patients at the F3, FZ, Cz, C4, Pz, and P4 electrode sites than for healthy elderly controls. Moderate correlations were found between Stroop test score and P4 amplitude, digit span forward and C3 and Pz amplitude, and digit span backward and O1 amplitude. The major finding of this study was the detection of cognitive changes by electrophysiological methods in PD patients who were indicated to be cognitively normal by neuropsychological tests. These finding suggests that cognitive changes in PD patients, which are not yet reflected in neuropsychological tests, may be detected by electrophysiological methods in earlier stages.

Brain temporal complexity in explaining the therapeutic and cognitive effects of seizure therapy.

Over 350 million people worldwide suffer from depression, a third of whom are medication-resistant. Seizure therapy remains the most effective treatment in depression, even when many treatments fail. The utility of seizure therapy is limited due to its cognitive side effects and stigma. The biological targets of seizure therapy remain unknown, hindering design of new treatments with comparable efficacy. Seizures impact the brains temporal dynamicity observed through electroencephalography. This dynamicity reflects richness of information processing across distributed brain networks subserving affective and cognitive processes. We investigated the hypothesis that seizure therapy impacts mood (depressive symptoms) and cognition by modulating brain temporal dynamicity. We obtained resting-state electroencephalography from 34 patients (age = 46.0 ± 14.0, 21 females) receiving two types of seizure treatments-electroconvulsive therapy or magnetic seizure therapy. We used multi-scale entropy to quantify the complexity of the brain's temporal dynamics before and after seizure therapy. We discovered that reduction of complexity in fine timescales underlined successful therapeutic response to both seizure treatments. Greater reduction in complexity of fine timescales in parieto-occipital and central brain regions was significantly linked with greater improvement in depressive symptoms. Greater increase in complexity of coarse timescales was associated with greater decline in cognition including the autobiographical memory. These findings were region and timescale specific. That is, change in complexity in occipital regions (e.g. O2 electrode or right occipital pole) at fine timescales was only associated with change in depressive symptoms, and not change in cognition, and change in complexity in parieto-central regions (e.g. Pz electrode or intra and transparietal sulcus) at coarser timescale was only associated with change in cognition, and not depressive symptoms. Finally, region and timescale specific changes in complexity classified both antidepressant and cognitive response to seizure therapy with good (80%) and excellent (95%) accuracy, respectively. In this study, we discovered a novel biological target of seizure therapy: complexity of the brain resting state dynamics. Region and timescale dependent changes in complexity of the brain resting state dynamics is a novel mechanistic marker of response to seizure therapy that explains both the antidepressant response and cognitive changes associated with this treatment. This marker has tremendous potential to guide design of the new generation of antidepressant treatments.

ERPs Differentially Reflect Automatic and Deliberate Processing of the Functional Manipulability of Objects.

It is known that the functional properties of an object can interact with perceptual, cognitive, and motor processes. Previously we have found that a between-subjects manipulation of judgment instructions resulted in different manipulability-related memory biases in an incidental memory test. To better understand this effect we recorded electroencephalography (EEG) while participants made judgments about images of objects that were either high or low in functional manipulability (e.g., hammer vs. ladder). Using a between-subjects design, participants judged whether they had seen the object recently (Personal Experience), or could manipulate the object using their hand (Functionality). We focused on the P300 and slow-wave event-related potentials (ERPs) as reflections of attentional allocation. In both groups, we observed higher P300 and slow wave amplitudes for high-manipulability objects at electrodes Pz and C3. As P300 is thought to reflect bottom-up attentional processes, this may suggest that the processing of high-manipulability objects recruited more attentional resources. Additionally, the P300 effect was greater in the Functionality group. A more complex pattern was observed at electrode C3 during slow wave: processing the high-manipulability objects in the Functionality instruction evoked a more positive slow wave than in the other three conditions, likely related to motor simulation processes. These data provide neural evidence that effects of manipulability on stimulus processing are further mediated by automatic vs. deliberate motor-related processing.

P300 amplitude and latency in autism spectrum disorder: a meta-analysis.

Autism spectrum disorder (ASD) is an early onset neurodevelopmental disorder. Evidence suggests that ASD patients have abnormalities in information processing. Event-related potential (ERP) technique can directly record brain neural activity in real time. P300 is a positive ERP component which can measure the neuroelectrophysiological characteristics of human beings and has the potential to discover the pathological mechanism of ASD. However, P300 studies on ASD patients are incongruent and the disparities may be caused by several factors. By searching PubMed, Embase and Cochrane Library databases, a meta-analysis of P300 component difference between ASD group and typically developed (TD) control group was conducted. Results of amplitude and latency of P3b and P3a from included studies were synthesized. Random effect model was chosen and standardized mean difference (SMD) was calculated. Subgroup analysis was used to identify the source of heterogeneity and to test the effect of different experiment factors. A total of 407 ASD patients and 457 TD controls from 32 studies were included in this analysis. Reduced amplitude of P3b was found in ASD group (SMD=-0.505, 95% CI -0.873, -0.138) compared with TD group, but no difference of P3b latency, P3a amplitude, or P3a latency was found between groups. Subgroup analysis showed that oddball paradigm elicited attenuated P3b amplitude in Pz electrode among ASD subjects. This meta-analysis suggests ASD patients have abnormalities in P300 component, which may represent for deficits in cognition, attention orientation and working memory processing, particularly in the decision-making processing condition.

Event-related potentials reflect the efficacy of pharmaceutical treatments in children and adolescents with attention deficit/hyperactivity disorder

Few objective biological measures of pharmacological treatment efficacy exist for attention deficit/hyperactivity disorder (ADHD). Although we have previously demonstrated that event-related potentials (ERPs) reflect the effects of osmotic-release methylphenidate in treatment of naïve pediatric patients with ADHD, whether this is true for the therapeutic effects of atomoxetine (ATX) is unknown. Here, we used the Japanese version of the ADHD rating-scale IV to evaluate 14 patients with ADHD, and compared their ERP data with 14 age- and sex-matched controls. We measured P300 and mismatch negativity (MMN) components during an auditory oddball task before treatment (treatment naïve) and after 2 months of ATX treatment. Compared with controls, P300 components at baseline were attenuated and prolonged in the ADHD group at Fz (fronto-central), Cz (centro-parietal), Pz (parietal regions), C3 and C4 electrodes. ATX treatment reduced ADHD symptomology, and after 2 months of treatment, P300 latencies at Fz, Cz, Pz, C3, and C4 electrodes were significantly shorter than those at baseline. Moreover, MMN amplitudes at Cz and C3 electrodes were significantly greater than those at baseline. Thus, ERPs may be useful for evaluating the pharmacological effects of ATX in pediatric and adolescent patients with ADHD.

Preference for Sucrose Solutions Modulates Taste Cortical Activity in Humans.

High time resolution is required to reliably measure neuronal activity in the gustatory cortex in response to taste stimuli. Hedonic aspects of gustatory processing have never been explored using gustatory evoked potentials (GEPs), a high-time-resolution technique. Our aim was to study cerebral processing of hedonic taste in humans using GEPs in response to sucrose solutions in subjects with different ratings of pleasantness regarding sucrose. In this exploratory study, 30 healthy volunteers were randomly stimulated with 3 sucrose solutions. The sucrose stimulus was presented to the tongue for 1s 20 times. GEPs were recorded from 9 cortical sites with EEG sensors at Cz, Fz, Pz, C3, C4, F3, F4, Fp1, and Fp2 (10/20 system). The main result was that subjects who preferred the high-concentration (20g/100mL) sucrose solution had higher GEP amplitudes on the Pz, Cz, and Fz electrodes than did subjects who preferred the low-concentration (5g/100mL) or the moderate-concentration (10g/100mL) solutions regardless of stimulus intensity. The difference in P1N1 amplitude on the Pz, Cz, and Fz electrodes according to sucrose preference of the subjects was described with stronger significance with stimulation by the 20 g-sucrose solution than by the 5 and 10g sucrose solutions. Using the reliable and safe GEP technique, we provide an original demonstration of variability of the gustatory response on the Pz, Cz, and Fz electrodes according to a sweet preference in humans. Further studies are needed to correlate the electric signal recorded by surface electrodes to the neural generator.

Go and NoGo: modulation of electrophysiological correlates by female sex steroid hormones.

The behavioral and electrophysiological responses in a Go/NoGo task are objective measures of executive functioning that may be impaired in clinical conditions. Prior to the wider application of Go/NoGo tasks in clinics, it is tempting to evaluate factors causing modulation of the responses. We aimed to evaluate the effect of different levels of female sex steroids on Go/NoGo task-related ERPs in healthy females. Thirty-four young healthy females performed an equiprobable (50/50) auditory Go/NoGo task. Amplitudes and latencies of N2 and P3 peaks from Fz, Cz, and Pz electrodes were evaluated. 17β-estradiol and progesterone levels in saliva samples were measured. Electrophysiological measures were correlated to 17β-estradiol and progesterone concentrations. The diverse pattern of modulation of P3 latencies was shown: higher levels of 17β-estradiol contributed to Go-P3 latency prolongation, and higher levels of progesterone contributed to NoGo-P3 latency shortening. Higher levels of 17β-estradiol were associated with more negative frontal N2 amplitude in both conditions. The relationship between electrophysiological correlates of executive functioning to individual hormonal levels points to a broader range of variation sources in healthy subjects which might mask or pronounce between-group differences in clinical studies.

Attenuation of visual search deficits through complimentary tactile stimulation in low luminance environments: evidence from ERP and eye tracking analyses.

Event Abstract Back to Event Attenuation of visual search deficits through complimentary tactile stimulation in low luminance environments: evidence from ERP and eye tracking analyses. Mathew Hunter1*, Bettina Olk2 and Ben Godde1 1 Jacobs University, Germany 2 HSD Hochschule Döpfer, University of Applied Sciences, Germany Searching for a visual target among distractors is one of the most common yet complex tasks we are facing in our everyday lives. Despite the fact that our visual search mechanisms are quite adept, we are still subject to limitations of our visual processing which is particularly evident in environments of extremely low luminance (<0.5 cd/m2). Even with a thorough understanding of visual perception in low luminance environments, little is known regarding search processes within these conditions [1], and subsequently, the primary contributing factors to decreases in performance that are observed in these environments and if there are any mechanisms for attenuation. Hunter et al. [2] have provided contrast efficiency functions for simple visual search tasks within the low luminance spectrum, which specifically relate the cumulative effects of relative contrast luminance and the innate contrast of complex target stimuli to search performance. In an attempt to understand the mechanisms behind decreases in performance and how such decreases could be attenuated we have also demonstrated that different aspects of tactile stimulation, such as the predictive probability of a tactile stimulus, or type of tactile stimulation (spatial or frequency information regarding the location of a target), could be used to improve search performance and their fitting along an efficiency function [3]. We suggested a “gating window” providing the psychophysical boundaries pertaining to when in the visual search process tactile information can improve performance, and how this changes with respect to different tactile properties. We observed that coding of a tactile stimulus is only beneficial when a minimum mean response time of 500 ms is required in order to solve the task. The goal of the present study was to assess the neurophysiological mechanisms related to the reception of visual and complimentary tactile information and the visual scanning process. To this end we incorporated measurements of scan patterns (eye tracking) and of event related potentials (ERP). To isolate the temporal determinants of the “gating window”, we specifically focused on the early perceptual components that relate to the visual and tactile reception and integration spanning the first 500 ms of a trial. We targeted seven individual ERP components: P45, N80, P100, N140, N180, N2, and P300 and selected from the Fz, Cz, Pz, C3, C4, P3, P4, O1 and O2 electrodes. Eleven participants performed three different tactile-visual search (target present/absent) paradigms incorporating three different types of tactile encoding, i.e. frequency (20 Hz and 40 Hz stimulation), spatial (left vs right), and frequency and spatial, to provide information regarding the location of a target. We assessed in how far a given type of tactile stimulation was beneficial in improving visual search performance (adapted from [3]). Behavioural results replicated previous findings. The addition of a tactile stimulus designed to provide information about the target, improved performance (RT and d’) which is normally affected in low luminance environments; however, no differences were observed with respect to a specific tactile encoding type. Quantitative analyses of scan patterns measuring the number of saccades, fixation durations, search array dwell time and location were completed. Results revealed that the scan pattern variables were primarily influenced by tactile spatial coding (left vs right) with minimal effects observed in the frequency coding condition. The ERP results primarily implicated the N2 component at Fz, Cz and Pz electrodes as a contributing factor to performance demonstrated by a significant positive correlation with RT (0.87 p < 0.01) and a negative correlation (0.83 p < 0.01) for d’. More specifically, increased peak latencies reflected slower RTs and decreased performance. These correlations remained consistent independent of the type of tactile stimulation. With respect to scanning behavior, the N2 component over the C4 (0.75, p < 0.05) electrode correlated positively with the total number of fixations and negatively with the peak amplitude over the Cz electrode (Cz = -0.67, p < 0.005). The N2 component has been previously implicated in visual tactile cross-modal congruency paradigms [4], where incongruency reflects greater negative potential amplitudes. Consistent with our results, a greater incongruency or conflict would reflect poorer performance (slower RTs and poorer d’ score). Our results provide preliminary evidence with respect to the distinct integration gating component reported by Hunter et al. [3] and ultimately insight into the interactions of multi-sensory integration and performance. The individual components allowed verification of the gating, but more neural processing post this gating process that we did not examine with our study will contribute to response execution.

Low-frequency rTMS over the Parieto–frontal network during a sensorimotor task: The role of absolute beta power in the sensorimotor integration

Several studies have demonstrated that Repetitive Transcranial Magnetic Stimulation (rTMS) promotes alterations in the Central Nervous System circuits and networks. The focus of the present study is to examine the absolute beta power patterns in the Parieto–frontal network. We hypothesize that rTMS alters the mechanisms of the sensorimotor integration process during a visuomotor task. Twelve young healthy volunteers performed a visuomotor task involving decision making recorded (Catch a ball in a free fall) by Electroencephalography. rTMS was applied on the Superior Parietal Cortex (SPC; Brodmann area [BA] 7) with low-frequency (1Hz – 15min – 80% Resting Motor Threshold). For each Frontal and Parietal region, a two-way ANOVA was used to compare the absolute beta power before and after TMS for each condition of the study (Rest 1, Task and Rest 2). The results demonstrated interactions (TMS vs. Condition) for the Frontal electrodes: Fp1, Fp2 and F7 and an effect of TMS (before and after) for F4.The results for the Parietal region showed a main effect of Condition for the P3, PZ and P4 electrodes. Thus, our paradigm was useful to better understand the reorganization and neural plasticity mechanisms in the parieto–frontal network during the sensorimotor integration process.

Psychophysiological classification and experiment study for spontaneous EEG based on two novel mental tasks.

Study of imagination offers a perfect setting for study of a large variety of states of consciousness. Here, we studied the characteristics of two electroencephalographic (EEG) patterns evoked by two different imaginary tasks and evaluated the binary classification performance. Fifteen individuals (11 male and 4 female, age range of 22 to 33) participated in five sessions of 32-channel EEG recordings. Only by analyzing the subjects' output EEG signals from the central parieto-occipital region of PZ electrode, under the circumstances of consciousness of relaxation-meditation or tension-imagination, we carried out the experiment of feature extraction for spontaneous EEG, as the subjects were blindfolded but asked to open their eyes all the same. The Hilbert-Huang Transform (HHT) was utilized to obtain the Hilbert time-frequency amplitude spectrum, and then with the feature vector set extracted, a two-class Fisher linear discriminant analysis classifier was trained for classification of data epochs of those two tasks. The overall result was that about 90% (± 5%) of the epochs could be correctly classified to their originating task. This study not only brings new opportunities for consciousness studies, but also provides a new classification paradigm for achieving control of robots based on the brain-computer interface (BCI).

Emotional and cognitive processing in Parkinson's disease

Event Abstract Back to Event Emotional and cognitive processing in Parkinson's disease Nadeeka Dissanayaka1, 2*, Tiffany Au1, Anthony Angwin3, John O'Sullivan2, Gerard Byrne4, 5, Peter Silburn1, 2, Rodney Marsh4, 5, George Mellick2, 6 and David Copland1, 3 1 The University of Queensland Centre for Clinical Research and RBWH, UQ Centre for Clinical Research, Australia 2 Royal Brisbane & Women's Hospital, Neurology Research Centre, Australia 3 The University of Queensland Centre for Clinical Research and RBWH, School of Health & Rehabilitation Sciences, Australia 4 The University of Queensland Centre for Clinical Research and RBWH, School of Medicine, Australia 5 Royal Brisbane & Women's Hospital, Department of Psychiatry, Australia 6 Griffith University , Eskitis Institute for Cell & Molecular Therapies, Australia Background: Emotional dysfunction and cognitive impairment are frequent non-motor complications in Parkinson's disease (PD). Over 50% experience anxiety and depression, 25% experience mild cognitive impairment (MCI), and a further 25% experience dementia at end stage PD. However, mechanisms underpinning these neuropsychiatric disturbances in PD are poorly understood. This study aims to identify event related potentials (ERPs) associated with cognitive and affective processes in PD. Methods: Fifty three (53) PD patients completed a visual word affective priming task while ERPs were recorded. The task presented negative or neutral word pairs with a stimulus onset asynchrony of 250ms. Participants evaluated the valance of the second word (target word). Repeated measures ANOVAs were used to investigate the effects of Target Valence and Congruency on P3 and LPP ERP amplitudes. We also investigated the interactions between these factors and depression, anxiety and cognitive rating scale scores using covariance and subsequent partial correlations. Results: P3 and LPP amplitude deflections were larger for negative targets compared to neutral targets at Pz electrode (P3 F=6.82, p=0.01; for LPP F=5.88, p=0.01). Target valence X Congruency X Covariate interactions were observed for depression (P3 F=7.8, p<0.01; LPP F=4.30, p=0.04) and cognitive impairment (P3 F=10.3, p<0.01, LPP F=5.84, p=0.01). The P3 difference wave (incongruent - congruent) for neutral targets positively and independently correlated with depression (r=0.39, p=0.005) and cognitive impairment (r=0.33, p=0.02). Similarly, the LPP difference wave for neutral targets positively correlated with depression when adjusted for cognitive impairment and anxiety (r=0.35, p=0.02). Conclusion: P3 and LPP allow discrimination of negative biases associated with stimulus processing. These results demonstrate that depression and cognitive impairment independently influence the processing of negative prime words in PD. Keywords: Cognition, Depression, Parkinson's disease, Event Related Potentials, LPP, P3, negative biases Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Emotional and Social Processes Citation: Dissanayaka N, Au T, Angwin A, O'Sullivan J, Byrne G, Silburn P, Marsh R, Mellick G and Copland D (2015). Emotional and cognitive processing in Parkinson's disease. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00166 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Ms. Nadeeka Dissanayaka, The University of Queensland Centre for Clinical Research and RBWH, UQ Centre for Clinical Research, Brisbane, Australia, n.dissanayaka@uq.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Nadeeka Dissanayaka Tiffany Au Anthony Angwin John O'Sullivan Gerard Byrne Peter Silburn Rodney Marsh George Mellick David Copland Google Nadeeka Dissanayaka Tiffany Au Anthony Angwin John O'Sullivan Gerard Byrne Peter Silburn Rodney Marsh George Mellick David Copland Google Scholar Nadeeka Dissanayaka Tiffany Au Anthony Angwin John O'Sullivan Gerard Byrne Peter Silburn Rodney Marsh George Mellick David Copland PubMed Nadeeka Dissanayaka Tiffany Au Anthony Angwin John O'Sullivan Gerard Byrne Peter Silburn Rodney Marsh George Mellick David Copland Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Meta-analysis of P300 waveform in panic disorder.

The P300 waveform has been inconsistently linked to the maladaptive information-processing characterized in panic disorder (PD). The purpose of this study was to synthesize previous event-related potential (ERP) findings and determine whether patients with PD have significant abnormalities in the P300 wave compared to controls. We performed a systematic literature search for studies published between 1980 and 2013 that reported P300 measurements in patients with PD and controls. Effect size estimates were computed using the restricted maximum likelihood model. We identified 14 ERP studies that analyzed P300 amplitude (461 PD and 355 controls), and 11 ERP studies that analyzed latency (320 PD and 282 controls). Patients with PD had reduced P300 amplitudes compared to controls, but this difference was non significant at midline electrodes (n = 14, ES -0.16; z = -1.55, p = 0.122). However, P300 amplitude was significantly reduced when analyzing the Pz electrode independently (n = 7, ES -0.48, z = -3.92, p < 0.001). No significant differences between cases and controls in P300 latency were observed at the midline electrodes (n = 11, ES 0.11, z = 0.64, p = 0.524). This meta-analysis included non-peer reviewed literature and ERP stimuli with varying levels of emotional salience, which may have introduced bias into the analysis. There is no robust evidence that P300 latency alterations are present in patients with PD; however, there are indications of reduced amplitude at Pz relative to controls. Reductions in amplitude may be associated with reduced neural resources allocated to contextual updating, selective attention, and neural inhibition mechanisms.