Olivier Renaud

On neuro-wavelet modeling

We survey a number of applications of the wavelet transform in time series prediction. The Haar a trous wavelet transform is proposed as a means of handling time series data when future data is unknown. Results are exemplified on financial futures and S&P500 data. Nonlinear and linear multiresolution autoregressionmodels are studied. Experimentally, we show that multiresolution approaches can outperform the traditional single resolution approach to modeling and prediction.

Wavelet-based nonlinear multiscale decomposition model for electricity load forecasting

We propose a wavelet multiscale decomposition-based autoregressive approach for the prediction of 1-h ahead load based on historical electricity load data. This approach is based on a multiple resolution decomposition of the signal using the non-decimated or redundant Haar a trous wavelet transform whose advantage is taking into account the asymmetric nature of the time-varying data. There is an additional computational advantage in that there is no need to recompute the wavelet transform (wavelet coefficients) of the full signal if the electricity data (time series) is regularly updated. We assess results produced by this multiscale autoregressive (MAR) method, in both linear and non-linear variants, with single resolution autoregression (AR), multilayer perceptron (MLP), Elman recurrent neural network (ERN) and the general regression neural network (GRNN) models. Results are based on the New South Wales (Australia) electricity load data that is provided by the National Electricity Market Management Company (NEMMCO).

Do age differences between young and older adults in inhibitory tasks depend on the degree of activation of information

Three inhibition/interference tasks (Stroop colour, Negative priming embedded within the Stroop colour, and Hayling) were administered to young and older adults, with two main objectives, each of which embedded within a developmental perspective: First manipulate the level of activation of the irrelevant information, and second, assess the number of individuals presenting a reliable effect rather than analyse the results only at the group level. For each task, two versions were used, corresponding to two levels at which the irrelevant information was likely to be activated. Analyses were conducted on relative difference scores rather than on raw response times. Results indicated that age differences in the magnitude of an interference effect were small and even null in the Negative priming task, independently of the salience of the irrelevant information. A bootstrap procedure showed that whereas the majority of both young and older adults presented a reliable interference effect in the Stroop colour and in the Hayling tasks, it was not the case in the Negative priming task. Moreover, correlations between the indices of interference/inhibition were very weak questioning the dimensionality of inhibition. Altogether these findings suggest that highly activated versions of the inhibitory tasks used do not really influence age-related differences in inhibitory control. It is also recommended to use bootstrap procedures more frequently instead of restricting analyses at a group level.

Poor reward sensitivity and apathy after stroke: Implication of basal ganglia

Objective: To examine the relationship between reward sensitivity and self-reported apathy in stroke patients and to investigate the neuroanatomical correlates of both reward sensitivity and apathy. Methods: In this prospective study, 55 chronic stroke patients were administered a questionnaire to assess apathy and a laboratory task to examine reward sensitivity by measuring motivationally driven behavior (“reinforcement-related speeding”). Fifteen participants without brain damage served as controls for the laboratory task. Negative mood, working memory, and global cognitive functioning were also measured to determine whether reward insensitivity and apathy were secondary to cognitive impairments or negative mood. Voxel-based lesion-symptom mapping was used to explore the neuroanatomical substrates of reward sensitivity and apathy. Results: Participants showed reinforcement-related speeding in the highly reinforced condition of the laboratory task. However, this effect was significant for the controls only. For patients, poorer reward sensitivity was associated with greater self-reported apathy (p < 0.05) beyond negative mood and after lesion size was controlled for. Neither apathy nor reward sensitivity was related to working memory or global cognitive functioning. Voxel-based lesion-symptom mapping showed that damage to the ventral putamen and globus pallidus, dorsal thalamus, and left insula and prefrontal cortex was associated with poorer reward sensitivity. The putamen and thalamus were also involved in self-reported apathy. Conclusions: Poor reward sensitivity in stroke patients with damage to the ventral basal ganglia, dorsal thalamus, insula, or prefrontal cortex constitutes a core feature of apathy. These results provide valuable insight into the neural mechanisms and brain substrate underlying apathy.

Sex hormones and mental rotation: an intensive longitudinal investigation.

The present study used an intensive longitudinal design to examine whether mental rotation performance varies according to a monthly cycle in both males and females and whether these variations are related to variations in progesterone, estradiol, and testosterone levels. We collected reaction time and accuracy data for 10 males and seven females each workday over eight weeks using 136 pairs of mental rotation stimuli/day, and measured sexual hormones concentrations in the saliva twice a week. A mixed linear model statistical analysis revealed that all females and seven males showed significant cycle effects in mental rotation performance. The female cycle showed an amplitude that was twice as large compared with the amplitude found in males. For males and females, estradiol and testosterone were significantly linearly and quadratically related to interindividual variation in performance at the beginning of the study (progesterone was linearly related to performance for females). The association between testosterone and performance differed across sexes: for males, it had an inverse U-shape, for females it was U-shaped. Towards the end of the study, none of the hormones were significantly related to performance anymore. Thus, the relationship between hormones and mental rotation performance disappeared with repeated testing. Only estradiol levels were significantly elevated at the lowest point of the cycle in mental rotation performance in females. In conclusion, in this intensive longitudinal study spanning two months, a monthly cycle in mental rotation performance was found among both males and females, with a larger cycles amplitude for females.

Nocturnal Regrets and Insomnia in Elderly People

Despite their importance for general health, emotion-related factors have rarely been considered in the etiology of late-life insomnia. This study explored the relations between impulsivity, regret experiences, use of different thought-control strategies, and insomnia severity in a sample of older adults whose age ranged from 51 to 98 years. Results revealed that: (a) regret frequency varies across the hours of the day, with a peak in the evening when people are trying to fall asleep; (b) individuals scoring high on impulsive urgency are particularly prone to experience nocturnal regrets; (c) nocturnal regrets are associated with insomnia severity, independently of other well-known risk factors such as depression, sleep-interfering medical conditions, and medications; and (d) the thought-control strategies of self-attacking, thought suppression, and worry are positively associated with the frequency of nocturnal regrets and insomnia severity. These findings indicate that dysfunctional regret regulation plays an important role for sleep disturbances in elderly people.

A tutorial for analyzing human reaction times: How to filter data, manage missing values, and choose a statistical model

This tutorial for the statistical processing of reaction times collected through a repeated-measure design is addressed to researchers in psychology. It aims at making explicit some important methodological issues, at orienting researchers to the existing solutions, and at providing them some evaluation tools for choosing the most robust and precise way to analyze their data. The methodological issues we tackle concern data filtering, missing values management, and statistical modeling (F1, F2, F1 + F2, quasi-F, mixed-effects models with hierarchical, or with crossed factors). For each issue, references and remedy suggestions are given. In addition, modeling techniques are compared on real data and a benchmark is given for estimating the precision and robustness of each technique. The experimental method provides a highly efficient means for confronting theoretical models with reality in order to build and improve our understanding of nature. In an attempt to increase the scientific nature of their young discipline, psychologists adopted the experimental method as away to systematically describe and study human behavior. For this enterprise, they needed to “measure variables objectively,” and “accurately infer that the observed pattern of results reflects what typically happens” (Mitchell & Jolley, 2007). In other words, they needed to use statistical quantitative techniques. Statistical quantitative techniques are complex mathematical methods mainly used to draw linear relations between variables. These methods must be handled carefully in order to avoid biased conclusions and the creation of fallacious

Numerical Abilities in Children With Congenital Hemiplegia: An Investigation of the Role of Finger Use in Number Processing

In this study, we assessed basic and more complex non-symbolic and symbolic numerical task abilities in children with hemiplegia and obtained a detailed picture of their strengths and weaknesses in the numerical domain. Those children, who experience difficulties in finger gnosia and spontaneous use of fingers in counting, exhibit difficulties in finger pattern recognition and symbolic numerical tasks. However, their non-symbolic numerical abilities and arithmetic skills are preserved. These original results are discussed in light of the “manumerical cognition” hypothesis, which postulates that the use of fingers in numerical activities during childhood shapes our comprehension of numbers.

Robust analysis of the central tendency, simple and multiple regression and ANOVA: a step by step tutorial.

After much exertion and care to run an experiment in social science, the analysis of data should not be ruined by an improper analysis. Often, classical methods, like the mean, the usual simple and multiple linear regressions, and the ANOVA require normality and absence of outliers, which rarely occurs in data coming from experiments. To palliate to this problem, researchers often use some ad-hoc methods like the detection and deletion of outliers. In this tutorial, we will show the shortcomings of such an approach. In particular, we will show that outliers can sometimes be very difficult to detect and that the full inferential procedure is somewhat distorted by such a procedure. A more appropriate and modern approach is to use a robust procedure that provides estimation, inference and testing that are not influenced by outlying observations but describes correctly the structure for the bulk of the data. It can also give diagnostic of the distance of any point or subject relative to the central tendency. Robust procedures can also be viewed as methods to check the appropriateness of the classical methods. To provide a step-by-step tutorial, we present descriptive analyses that allow researchers to make an initial check on the conditions of application of the data. Next, we compare classical and robust alternatives to ANOVA and regression and discuss their advantages and disadvantages. Finally, we present indices and plots that are based on the residuals of the analysis and can be used to determine if the conditions of applications of the analyses are respected. Examples on data from psychological research illustrate each of these points and for each analysis and plot, R code is provided to allow the readers to apply the techniques presented throughout the article.

Vocal emotion decoding in the subthalamic nucleus: An intracranial ERP study in Parkinson’s disease

&NA; Using intracranial local field potential (LFP) recordings in patients with Parkinsons disease (PD) undergoing deep brain stimulation (DBS), we explored the electrophysiological activity of the subthalamic nucleus (STN) in response to emotional stimuli in the auditory modality. Previous studies focused on the influence of visual stimuli. To this end, we recorded LFPs within the STN in response to angry, happy, and neutral prosodies in 13 patients with PD who had just undergone implantation of DBS electrodes. We observed specific modulation of the right STN in response to anger and happiness, as opposed to neutral prosody, occurring at around 200–300 ms post‐onset, and later at around 850–950 ms post‐onset for anger and at around 3250–3350 ms post‐onset for happiness. Taken together with previous reports of modulated STN activity in response to emotional visual stimuli, the present results appear to confirm that the STN is involved in emotion processing irrespective of stimulus valence and sensory modality. Graphical abstract Figure. No caption available. HighlightsWe explored the STNs electrophysiological activity in response to auditory emotions.We recorded LFPs in 13 patients with Parkinsons disease who had undergone DBS.We observed a specific activity of the right STN in response to angry and happy voices.STN is involved in human emotion, irrespective of valence and sensory modality.