Cognitive effects of rhythmic auditory stimulation in Parkinson's disease: A P300 study

Probing Beat Perception with Event-Related Potentials (ERPs) in Human Adults, Newborns, and Nonhuman Primates

The aim of this chapter is to give an overview of how the perception of rhythmic temporal regularity such as a regular beat in music can be studied in human adults, human newborns, and nonhuman primates using event-related brain potentials (ERPs). First, we discuss different aspects of temporal structure in general, and musical rhythm in particular, and we discuss the possible mechanisms underlying the perception of regularity (e.g., a beat) in rhythm. Additionally, we highlight the importance of dissociating beat perception from the perception of other types of structure in rhythm, such as predictable sequences of temporal intervals, ordinal structure, and rhythmic grouping. In the second section of the chapter, we start with a discussion of auditory ERPs elicited by infrequent and frequent sounds: ERP responses to regularity violations, such as mismatch negativity (MMN), N2b, and P3, as well as early sensory responses to sounds, such as P1 and N1, have been shown to be instrumental in probing beat perception. Subsequently, we discuss how beat perception can be probed by comparing ERP responses to sounds in regular and irregular sequences, and by comparing ERP responses to sounds in different metrical positions in a rhythm, such as on and off the beat or on strong and weak beats. Finally, we will discuss previous research that has used the aforementioned ERPs and paradigms to study beat perception in human adults, human newborns, and nonhuman primates. In doing so, we consider the possible pitfalls and prospects of the technique, as well as future perspectives.

Dopamine dysregulation in Parkinson's disease flattens the pleasurable urge to move to musical rhythms

The pleasurable urge to move to music (PLUMM) activates motor and reward areas of the brain and is thought to be driven by predictive processes. Dopamine in motor and limbic networks is implicated in beat-based timing and music-induced pleasure, suggesting a central role of basal ganglia (BG) dopaminergic systems in PLUMM. This study tested this hypothesis by comparing PLUMM in participants with Parkinson's disease (PD), age-matched controls, and young controls. Participants listened to musical sequences with varying rhythmic and harmonic complexity (low, medium and high), and rated their experienced pleasure and urge to move to the rhythm. In line with previous results, healthy younger participants showed an inverted U-shaped relationship between rhythmic complexity and ratings, with preference for medium complexity rhythms, while age-matched controls showed a similar, but weaker, inverted U-shaped response. Conversely, PD showed a significantly flattened response for both the urge to move and pleasure. Crucially, this flattened response could not be attributed to differences in rhythm discrimination and did not reflect an overall decrease in ratings. For harmonic complexity, PD showed a negative linear pattern for both the urge to move and pleasure while healthy age-matched controls showed the same pattern for pleasure and an inverted U for the urge to move. This contrasts with the pattern observed in young healthy controls in previous studies, suggesting that both healthy aging and PD also influence affective responses to harmonic complexity. Together, these results support the role of dopamine within cortico-striatal circuits in the predictive processes that form the link between the perceptual processing of rhythmic patterns and the affective and motor responses to rhythmic music.

Top-down control of human motor thalamic neuronal activity during the auditory oddball task

The neurophysiology of selective attention in visual and auditory systems has been studied in animal models but not with single unit recordings in human. Here, we recorded neuronal activity in the ventral intermediate nucleus as well as the ventral oral anterior, and posterior nuclei of the motor thalamus in 25 patients with parkinsonian (n = 6) and non-parkinsonian tremors (n = 19) prior to insertion of deep brain stimulation electrodes while they performed an auditory oddball task. In this task, patients were requested to attend and count the randomly occurring odd or "deviant" tones, ignore the frequent standard tones and report the number of deviant tones at trial completion. The neuronal firing rate decreased compared to baseline during the oddball task. Inhibition was specific to auditory attention as incorrect counting or wrist flicking to the deviant tones did not produce such inhibition. Local field potential analysis showed beta (13-35 Hz) desynchronization in response to deviant tones. Parkinson's disease patients off medications had more beta power than the essential tremor group but less neuronal modulation of beta power to the attended tones, suggesting that dopamine modulates thalamic beta oscillations for selective attention. The current study demonstrated that ascending information to the motor thalamus can be suppressed during auditory attending tasks, providing indirect evidence for the searchlight hypothesis in humans. These results taken together implicate the ventral intermediate nucleus in non-motor cognitive functions, which has implications for the brain circuitry for attention and the pathophysiology of Parkinson's disease.

Pre-stimulus beta power varies as a function of auditory-motor synchronization and temporal predictability

Introduction

Auditory-motor interactions can support the preparation for expected sensory input. We investigated the periodic modulation of beta activity in the electroencephalogram to assess the role of active auditory-motor synchronization. Pre-stimulus beta activity (13–30 Hz) has been interpreted as a neural signature of the preparation for expected sensory input.

Methods

In the current study, participants silently counted frequency deviants in sequences of pure tones either during a physically inactive control condition or while pedaling on a cycling ergometer. Tones were presented either rhythmically (at 1 Hz) or arrhythmically with variable intervals. In addition to the pedaling conditions with rhythmic (auditory-motor synchronization, AMS) or arrhythmic stimulation, a self-generated stimulus condition was used in which tones were presented in sync with the participants’ spontaneous pedaling. This condition served to explore whether sensory predictions are driven primarily by the auditory or by the motor system.

Results

Pre-stimulus beta power increased for rhythmic compared to arrhythmic stimulus presentation in both sitting and pedaling conditions but was strongest in the AMS condition. Furthermore, beta power in the AMS condition correlated with motor performance, i.e., the better participants synchronized with the rhythmic stimulus sequence, the higher was pre-stimulus beta power. Additionally, beta power was increased for the self-generated stimulus condition compared with arrhythmic pedaling, but there was no difference between the self-generated and the AMS condition.

Discussion

The current data pattern indicates that pre-stimulus beta power is not limited to neuronal entrainment (i.e., periodic stimulus presentation) but represents a more general correlate of temporal anticipation. Its association with the precision of AMS supports the role of active behavior for auditory predictions.

The sweet spot between predictability and surprise: musical groove in brain, body, and social interactions

Groove-defined as the pleasurable urge to move to a rhythm-depends on a fine-tuned interplay between predictability arising from repetitive rhythmic patterns, and surprise arising from rhythmic deviations, for example in the form of syncopation. The perfect balance between predictability and surprise is commonly found in rhythmic patterns with a moderate level of rhythmic complexity and represents the sweet spot of the groove experience. In contrast, rhythms with low or high complexity are usually associated with a weaker experience of groove because they are too boring to be engaging or too complex to be interpreted, respectively. Consequently, the relationship between rhythmic complexity and groove experience can be described by an inverted U-shaped function. We interpret this inverted U shape in light of the theory of predictive processing and provide perspectives on how rhythmic complexity and groove can help us to understand the underlying neural mechanisms linking temporal predictions, movement, and reward. A better understanding of these mechanisms can guide future approaches to improve treatments for patients with motor impairments, such as Parkinson's disease, and to investigate prosocial aspects of interpersonal interactions that feature music, such as dancing. Finally, we present some open questions and ideas for future research.

Predictive value of P300 event-related potential component in early cognitive impairment in patients with uncomplicated newly diagnosed hepatitis C virus

Background

Cognitive impairment in patients with hepatitis C virus (HCV) is reported in the early onset of HCV infection without hepatic cirrhosis or marked liver impairment. Methods currently available to identify the risk for early cognitive impairment in hepatitis C virus (HCV) infection do not combine enough sensitivity and specificity. The present study aimed to evaluate the P 300 components of event-related potential (ERP) abnormalities as valid biomarkers for prediction and diagnosis of the cognitive impairment in newly diagnosed hepatitis C virus infection. This study is a case–control involved fifty patients newly diagnosed HCV and fifty age and sex-matched healthy controls. Assessments of cognitive functions were carried out by the Mini-mental State Examination, Wechsler Memory Scale Revised short form, and The Wechsler Adult Intelligence Scale, in addition to estimation of the amplitude and the latency of the P300 by the event-related potentials.

Results

Neuropsychological scales suggested the early incidence of cognitive impairment among hepatitis C virus patients. The electrophysiological study showed significant prolongation of P300 latency and decreased amplitude in HCV patients group compared with the control group. A binary logistic regression detected that P 300 latency ≥ 369 ms was significantly accompanied by a threefold increased risk of impaired cognition (OR 3.09, 95% CI 1.59–5.72, P < 0.01), while P 300 amplitude ≤ 8.2 μv was significantly accompanied by a twofold increased risk of impaired cognition (OR 2.18, 95% 1.43–4.05, P < 0.01).

Conclusion

This study concluded that the P300 event-related potentials components are valid biomarker as easy, noninvasive assessment and cost-effective method of early cognitive impairment in patients with uncomplicated newly diagnosed hepatitis C virus.

Registration of Clinical Trial Research

ClinicalTrials.gov ID: NCT04389268. https://clinicaltrials.gov/ct2/show/NCT04389268

Executive deficits in neuropsychological testing differentiate between autoimmune temporal lobe epilepsy caused by limbic encephalitis and temporal lobe epilepsies with non-autoimmune etiologies

OBJECTIVE

Patients with temporal lobe epilepsy caused by autoimmune limbic encephalitis (AI-TLE) clinically resemble patients with temporal lobe epilepsy with non-autoimmune etiologies (NAI-TLE) but have a different prognosis and require specific adjusted therapies. The objective of this study was to investigate whether patients with these forms of TLE can be discerned by means of neuropsychological assessment.

METHODS

Data from 103 patients with TLE (n = 39 with AI-TLE and n = 64 with NAI-TLE, including n = 39 with hippocampal sclerosis [HS] and n = 25 with low-grade epilepsy-associated tumors [LEAT]) and 25 healthy controls who underwent comprehensive neuropsychological assessments were analyzed retrospectively. The neuropsychological characteristics (mean z-scores) were compared between groups using one-way ANOVA, independent-samples t-tests, and discriminant function analysis (DFA).

RESULTS

The groups of patients with TLE showed significantly lower performance in attentional, visuospatial, verbal memory, and nonverbal memory functions compared to the healthy controls. Solely in the domain of executive functions, patients with AI-TLE showed significantly lower performance compared to patients with NAI-TLE regarding cognitive flexibility (p = 0.002) and verbal fluency (p = 0.018). Moreover, the DFA identified cognitive flexibility to be most appropriate to differentiate between patients with AI-TLE and patients with HS. Group membership was correctly predicted through neuropsychological assessment alone in 66.7% of the patients using cross-validation.

SIGNIFICANCE

We were able to identify specific neuropsychological features in our sample of patients with AI-TLE. While all groups of patients with TLE showed the expected TLE-typical memory impairments, significant differences between patients with AI-TLE and NAI-TLE were present only in the cognitive domain of executive functions. This finding facilitates the choice of suitable psychometric tests in clinical routine and, thus, the clinical differential diagnosis between these entities.

The Application of P300-Long-Latency Auditory-Evoked Potential in Parkinson Disease

Introduction Parkinson disease (PD) is a degenerative and progressive neurological disorder characterized by resting tremor, stiffness, bradykinesia, and postural instability. Despite the motor symptoms, PD patients also consistently show cognitive impairment or executive dysfunction. The auditory event-related potential P300 has been described as the best indicator of mental function, being highly dependent on cognitive skills, including attention and discrimination.

Objective To review the literature on the application and findings of P300 as an indicator of PD.

Data Analysis The samples ranged from 7 to 166 individuals. Young adult and elderly male patients composed most study samples. The Mini-Mental State Examination test, the Unified Parkinson Disease Rating Scale, and the Hoehn and Yahr Scale were used to assess neurological and cognitive function. In terms of testing hearing function, few studies have focused on parameters other than the P300. The factors we focused on were how the P300 was modified by cognitive effects, its correlation with different PD scales, the effect of performing dual tasks, the effect of fatigue, and the influence of drug treatments.

Conclusion The use of the P300 appears to be an effective assessment tool in patients with PD. This event-related potential seems to correlate well with other neurocognitive tests that measure key features of the disease.

Effect of Short-Term Metro-Rhythmic Stimulations on Gait Variability

The aim of the study was to define the effect of different short-term metro-rhythmic stimulations on the time and spatial parameters of gait. The secondary goal was to test whether prior instructions on how to respond to stimulations played a significant role in the stimulation by sound stimuli. Experimental tests of gait were conducted on a group of 36 healthy participants: group 1—subjects who were not informed how to react after hearing sound stimuli, group 2—subjects who received a clear instruction before the test to adjust the frequency of taking steps to the rhythm of the music. The gait research was carried out on a Zebris FDM-S (zebris Medical Gmbh, Isny, Germany) treadmill for various sound stimuli (arrhythmic stimulus, rhythmic stimuli at different rate). It was shown that a short-term influence of metro-rhythmic stimulations changes the time and spatial parameters of gait, i.e., gait frequency, length and duration of the gait cycle. The greatest impact on the modification of the time–space parameters of walking is exerted by rhythmic stimuli at a pace different from the frequency of gait at a preferred velocity. Providing information on how to respond to sounds heard may be important in gait therapy with RAS (rhythmic auditory stimulation).

Improved Activity Recognition Combining Inertial Motion Sensors and Electroencephalogram Signals

Human activity recognition and neural activity analysis are the basis for human computational neureoethology research dealing with the simultaneous analysis of behavioral ethogram descriptions and neural activity measurements. Wireless electroencephalography (EEG) and wireless inertial measurement units (IMU) allow the realization of experimental data recording with improved ecological validity where the subjects can be carrying out natural activities while data recording is minimally invasive. Specifically, we aim to show that EEG and IMU data fusion allows improved human activity recognition in a natural setting. We have defined an experimental protocol composed of natural sitting, standing and walking activities, and we have recruited subjects in two sites: in-house ([Formula: see text]) and out-house ([Formula: see text]) populations with different demographics. Experimental protocol data capture was carried out with validated commercial systems. Classifier model training and validation were carried out with scikit-learn open source machine learning python package. EEG features consist of the amplitude of the standard EEG frequency bands. Inertial features were the instantaneous position of the body tracked points after a moving average smoothing to remove noise. We carry out three validation processes: a 10-fold cross-validation process per experimental protocol repetition, (b) the inference of the ethograms, and (c) the transfer learning from each experimental protocol repetition to the remaining repetitions. The in-house accuracy results were lower and much more variable than the out-house sessions results. In general, random forest was the best performing classifier model. Best cross-validation results, ethogram accuracy, and transfer learning were achieved from the fusion of EEG and IMUs data. Transfer learning behaved poorly compared to classification on the same protocol repetition, but it has accuracy still greater than 0.75 on average for the out-house data sessions. Transfer leaning accuracy among repetitions of the same subject was above 0.88 on average. Ethogram prediction accuracy was above 0.96 on average. Therefore, we conclude that wireless EEG and IMUs allow for the definition of natural experimental designs with high ecological validity toward human computational neuroethology research. The fusion of both EEG and IMUs signals improves activity and ethogram recognition.

P300 Measures and Drive-Related Risks: A Systematic Review and Meta-Analysis

Detecting signs for an increased level of risk during driving are critical for the effective prevention of road traffic accidents. The current study searched for literature through major databases such as PubMed, EBSCO, IEEE, and ScienceDirect. A total of 14 articles that measured P300 components in relation to driving tasks were included for a systematic review and meta-analysis. The risk factors investigated in the reviewed articles were summarized in five categories, including reduced attention, distraction, alcohol, challenging situations on the road, and negative emotion. A meta-analysis was conducted at both behavioral and neural levels. Behavioral performance was measured by the reaction time and driving performance, while the neural response was measured by P300 amplitude and latency. A significant increase in reaction time was identified when drivers were exposed to the risk factors. In addition, the significant effects of a reduced P300 amplitude and prolonged P300 latency indicated a reduced capacity for cognitive information processing. There was a tendency of driving performance decrement in relation to the risk factors, however, the effect was non-significant due to considerable variations and heterogeneity across the included studies. The results led to the conclusion that the P300 amplitude and latency are reliable indicators and predictors of the increased risk in driving. Future applications of the P300-based brain–computer interface (BCI) system may make considerable contributions toward preventing road traffic accidents.

The P300 Event-Related Potential Component and Cognitive Impairment in Epilepsy: A Systematic Review and Meta-analysis

Background: Epilepsy is one of the most prevalent chronic brain diseases worldwide and is often accompanied by cognitive impairment. Event-related potentials (ERPs) are an objectively non-invasive approach for studying information processing and cognitive functions in the brain. The P300 is an important and extensively explored late component of ERPs that has been widely applied to assess cognitive function in epilepsy in previous studies. However, consistent conclusions have not yet been reached for various reasons.

Objective: We conducted a comprehensive systematic review and meta-analysis of P300-related studies to assess the latency and amplitude of the P300 in epileptic patients.

Methods: PubMed, EMBASE, and Cochrane Library databases were systematically searched for eligible studies. The standard mean difference (SMD) and the 95% confidence interval (CI) were calculated as the effect size of the P300 component.

Results: The main results of the present meta-analysis indicated that epileptic patients have a longer P300 latency and a lower P300 amplitude than controls. Subgroup analysis based on age group demonstrated that these differences can be observed in both children and adult patients compared with healthy controls. In addition, the P300 latency was longer in patients with the five main types of epileptic seizures than in controls.

Conclusion: This study revealed that epileptic patients have abnormalities in the P300 component, which may reflect deficits in cognitive function. Thus, the P300 may be a potential objective approach for evaluating cognitive function in epileptic patients.