Analytical methods and experimental approaches for electrophysiological studies of brain oscillations

Brain oscillations are increasingly the subject of electrophysiological studies probing their role in the functioning and dysfunction of the human brain. In recent years this research area has seen rapid and significant changes in the experimental approaches and analysis methods. This article reviews these developments and provides a structured overview of experimental approaches, spectral analysis techniques and methods to establish relationships between brain oscillations and behaviour

CoSMoMVPA: Multi-Modal Multivariate Pattern Analysis of Neuroimaging Data in Matlab/GNU Octave

Recent years have seen an increase in the popularity of multivariate pattern (MVP) analysis of functional magnetic resonance (fMRI) data, and, to a much lesser extent, magneto- and electro-encephalography (M/EEG) data. We present CoSMoMVPA, a lightweight MVPA (MVP analysis) toolbox implemented in the intersection of the Matlab and GNU Octave languages, that treats both fMRI and M/EEG data as first-class citizens. CoSMoMVPA supports all state-of-the-art MVP analysis techniques, including searchlight analyses, classification, correlations, representational similarity analysis, and the time generalization method. These can be used to address both data-driven and hypothesis-driven questions about neural organization and representations, both within and across: space, time, frequency bands, neuroimaging modalities, individuals, and species. It uses a uniform data representation of fMRI data in the volume or on the surface, and of M/EEG data at the sensor and source level. Through various external toolboxes, it directly supports reading and writing a variety of fMRI and M/EEG neuroimaging formats, and, where applicable, can convert between them. As a result, it can be integrated readily in existing pipelines and used with existing preprocessed datasets. CoSMoMVPA overloads the traditional volumetric searchlight concept to support neighborhoods for M/EEG and surface-based fMRI data, which supports localization of multivariate effects of interest across space, time, and frequency dimensions. CoSMoMVPA also provides a generalized approach to multiple comparison correction across these dimensions using Threshold-Free Cluster Enhancement with state-of-the-art clustering and permutation techniques. CoSMoMVPA is highly modular and uses abstractions to provide a uniform interface for a variety of MVP measures. Typical analyses require a few lines of code, making it accessible to beginner users. At the same time, expert programmers can easily extend its functionality. CoSMoMVPA comes with extensive documentation, including a variety of runnable demonstration scripts and analysis exercises (with example data and solutions). It uses best software engineering practices including version control, distributed development, an automated test suite, and continuous integration testing. It can be used with the proprietary Matlab and the free GNU Octave software, and it complies with open source distribution platforms such as NeuroDebian. CoSMoMVPA is Free/Open Source Software under the permissive MIT license. Website: http://cosmomvpa.org Source code: https://github.com/CoSMoMVPA/CoSMoMVPA

Examining the Role of Behavioral Inhibition in Harsh Parenting Preferences: An Analog Study

Understanding the cognitive processes involved in harsh parenting behavior would have broad implications for parenting interventions and training programs. Few studies have addressed how parental stressors, specifically infant crying, can influence individuals’ self-regulatory cognitive capacities and ultimately their preference for harsh parenting strategies. Furthermore, little research has explored the link between these cognitive processes and harsh parenting preferences; thus, little work has been done to establish a true causal relationship. This study examined the role of behavioral inhibition in harsh parenting preferences when individuals were exposed to an infant crying noise. Participants (n = 129) were undergraduate students (Mage = 19.97 years; 79.8% female; 47.3% African American, 39.5% Caucasian) who were randomly assigned to one of two conditions: (1) white noise and (2) infant crying noise. During the experiment they completed a cognitive task to capture their behavioral inhibition as well as measures of emotion regulation, parenting attitudes/beliefs, and other predictors of harsh parenting. Hierarchical multiple regression analyses indicated that infant crying noise did not moderate the relationship between behavioral inhibition and harsh parenting preferences. However, as hypothesized, the analyses indicated that lower behavioral inhibition predicted harsher physical parenting preferences. In addition, gender differences in harsh parenting preferences were explored using analysis of covariance analyses, which indicated that males and females did not differ in harsh parenting preferences. However, the current study did not collect enough males to meet power criteria, which may explain this non-significant effect. Methodological implications and recommendations for future research are discussed

Neural correlates of the processing of visually simulated self-motion

Successful interaction with our environment requires the perception of our surroundings. For coping with everyday challenges our own movements in this environment are important. In my thesis, I have investigated the neural correlates of visually simulated self-motion. More specifically, I have analyzed the processing of two key features of visual self-motion: the self-motion direction (heading) and the traveled distance (path integration) by means of electroencephalogram (EEG) measurements and transcranial magnetic stimulation (TMS). I have focused on investigating the role of prediction about the upcoming sensory event on the processing of these self-motion features. To this end, I applied the approach of the predictive coding theory. In this context, prediction errors induced by the mismatch between predictions and the actual sensory input are used to update the internal model responsible for creating the predictions. Additionally, I aimed to combine my findings with the results of previous studies on monkeys in order to further probe the role of the macaque monkey as an animal model for human sensorimotor processing. In my first study, I investigated the processing of different self-motion directions using a classical oddball EEG measurement. The frequently presented self-motion stimuli to one direction were interspersed with a rarely presented different self-motion direction. The headings occurred with different probabilities which modified the prediction about the upcoming event and allowed for the formulation of an internal model. Unexpected self-motion directions created a prediction error. I could prove this in my data by detecting a specific EEG-component, the mismatch negativity (MMN). This MMN-component does not only reveal the influence of predictions on the processing of visually simulated self-motion directions according to the predictive coding theory, but is also known to indicate the preattentive processing of the analyzed feature, here the heading. EEG data from monkeys was recorded with identical equipment during the presentation of the previously described stimulus by colleagues from my lab in order to test for the similarities in monkey and human processing of visually simulated self-motion. Remarkably, data showing a MMN-component similar to the human data was recorded. This led us to suggest that the underlying processes are comparable across human and non-human primates. In my second study, the objective was to causally link the human functional equivalent of macaque medial superior temporal area (hMST) to the perception of self-motion directions. In previous studies this area has been shown to be important for the processing of self-motion. Applying TMS to right hemisphere area hMST resulted in an increase in variance when participants were asked to estimate heading to the left, i.e. to the direction contraversive to the stimulation site. The results of this study were used to test a model developed by colleagues of my lab. They used findings from single cell recordings in macaque monkeys to create it. Simulating the influence of lateralized TMS pulses on one hemisphere hMST this model hypothesized an increase in variance for estimation of headings contraversive to the TMS stimulated hemisphere. This is exactly what I observed in data of my TMS experiment. In this second study I verified the finding of previous studies that hMST is important for the processing of self-motion directions. In addition, I showed that a model based on recordings from macaque monkeys can predict the outcome of an experiment with human participants. This indicates the similarity of the processing of visually simulated self-motion in humans and macaque monkeys. The third study focused on the representation of traveled distance using EEG recordings in human participants. The goal of this study was two-fold: First, I analyzed the influence of prediction on the processing of traveled distance. Second, I aimed to find a neural correlate of subjective traveled distance. Participants were asked to passively observe a forward self-motion. The movement onset and offset could not be predicted by them. In a next step participants reproduced double the distance of the previously observed self-motion. Since they actively modulated the movement to reach the desired distance, the resulting self-motion onset and offset could be predicted. Comparing the visually evoked potentials (VEPs) after self-motion onset and offsets of the predicted and unpredicted self-motion, I found differences supporting the predictive coding theory. Amplitudes for self-motion onset VEPs were larger in the passive condition. For self-motion offset, I found larger latencies for the VEP-components in the passive condition. In addition to these results I searched for a neural correlate of the subjective estimation of the distance presented in the passive condition. During the active reproduction of double the distance obviously the single distance was passed. I assumed that half of the reproduced double distance would be the subjective estimation of the single distance. When passing this subjective single distance, an increase in the alpha band activity was detected in half of the participants. At this point in time prediction about the upcoming movement changed since participants started reproducing the single distance again. In context of the predictive coding theory these prediction changes are considered to be feedback processes. It has been shown in previous studies that these kinds of feedback processes are associated with alpha oscillations. With this study, I demonstrated the influence of prediction on self-motion onset and offset VEPs as well as on brain oscillations during a distance reproduction experiment. In conclusion, with this thesis I analyzed the neural correlates of the processing of self-motion directions and traveled distance. The underlying neural mechanisms seem to be very similar in humans and macaque monkeys, which suggests the macaque monkey as an appropriate animal model for human sensorimotor processing. Lastly, I investigated the influence of prediction on EEG-components recorded during the processing of self-motion directions and traveled distances

Relación do ritmo alfa coa memoria de traballo e a demanda de recursos cognitivos no envellecemento san e con deterioracióncognitiva lixeira

A actividade oscilatoria na banda alfa tense relacionado co mantemento da información en memoria de traballo xogando tanto un papel inhibitorio en rexións irrelevantes para o procesamento da información como un papel facilitador da comunicación neural en rexións relevantes. Non obstante, hai unha escaseza de literatura sobre o seu papel nos cambios que acompañan ao envellecemento, tanto san como con deterioro cognitivo lixeiro (DCL). Dado que a memoria de traballo é unha das funcións cognitivas que se ve máis afectada tanto no envellecemento san como con DCL; nesta tese de doutoramento estudaremos a actividade alfa en fontes neurais durante o mantemento de información visoespacial en memoria de traballo, e ante diferentes niveis de demanda cognitiva, en mozos universitarios e en maiores cognitivamente sans e con DCL amnésico (DCLa). Os resultados obtidos sinalan que a actividade alfa en mozos actúa inhibindo rexións irrelevantes para a memoria de traballo; mentres que en maiores cognitivamente sans non só inhibe rexións irrelevantes, senon qué a menores niveis de demandas cognitiva tamén actúa como facilitador en rexións relevantes. Pola súa parte, os maiores con DCLa parecen non poder modular de maneira efectiva a súa actividade alfa, pois semellan inhibir rexións corticais relevantes para a tarefa. Á súa vez, observamos que o esforzo cognitivo previo parece afectar á actividade alfa espontánea en maiores cognitivamente sans pero non en maiores con DCLa; pois a actividade alfa en repouso relacionouse co rendemento e ca función cognitiva global nos primeiros, pero non nos maiores con DCLa

Cortical mechanisms for tinnitus in humans /

PhD ThesisThis work sought to characterise neurochemical and neurophysiological processes underlying tinnitus in humans. The first study involved invasive brain recordings from a neurosurgical patient, along with experimental manipulation of his tinnitus, to map the cortical system underlying his tinnitus. Widespread tinnitus-linked changes in low- and high-frequency oscillations were observed, along with inter-regional and cross-frequency patterns of communication. The second and third studies compared tinnitus patients to controls matched for age, sex and hearing loss, measuring auditory cortex spontaneous oscillations (with magnetoencephalography) and neurochemical concentrations (with magnetic resonance spectroscopy) respectively. Unlike in previous studies not controlled for hearing loss, there were no group differences in oscillatory activity attributable to tinnitus. However, there was a significant correlation between gamma oscillations (>30Hz) and hearing loss in the tinnitus group, and between delta oscillations (1-4Hz) and perceived tinnitus loudness. In the neurochemical study, tinnitus patients had significantly reduced GABA concentrations compared to matched controls, and within this group there was a positive correlation between choline concentration (potentially linked to acetylcholine and/or neuronal plasticity) and both hearing loss, and subjective tinnitus intensity and distress. In light of present and previous findings, tinnitus may be best explained by a predictive coding model of perception, which was tested in the final experiment. This directly controlled the three main quantities comprising predictive coding models, and found that delta/theta/alpha oscillations (1-12Hz) encoded the precision of predictions, beta oscillations (12-30Hz) encoded changes to predictions, and gamma oscillations represented surprise (unexpectedness of stimuli based on predictions). The work concludes with a predictive coding model of tinnitus that builds upon the present findings and settles unresolved paradoxes in the literature. In this, precursor processes (in varying combinations) synergise to increase the precision associated with spontaneous activity in the auditory pathway to the point where it overrides higher predictions of ‘silence’.Medical Research Council Wellcome Trust and the National Institutes of Healt