Modulating Effects of Emotional Valence on Recognition Memory for High-Arousal Pictures / Efectos moduladores de la valencia emocional sobre la memoria de reconocimiento para imágenes de alto arousal

ABSTRACT The main aim of this paper was to provide new evidence on the effects of valence on recognition memory of emotional pictures, on the basis of rigorous experimental control of stimulus material. Valence was manipulated using pleasant and unpleasant pictures, keeping arousal constant at a high level. A reference condition with a neutral value in both dimensions was also included. We found greater discrimination and a more conservative response bias, as well as slower recognition decisions, for pleasant pictures. Also worthy of mention is the high positive correlation between response times and discrimination measures just for such pictures. These results would be consistent with an adaptive interpretation based on motivation and personal relevance of emotional information.

RESUMEN El principal objetivo del presente trabajo fue aportar nueva evidencia sobre los efectos de la valencia en el reconocimiento de imágenes de contenido emocional, a partir de un riguroso control experimental del material estimular. Se manipuló la valencia a niveles agradable y desagradable, manteniendo constante el arousal a un nivel alto. Se incluyó también una condición de referencia con un valor neutro en ambas dimensiones. Se encontró una mejor discriminación, un sesgo de respuesta más conservador y un reconocimiento más lento para las imágenes agradables. Además, solo para estas imágenes existió alta correlación positiva entre tiempos de respuesta y discriminación. Estos resultados serían consistentes con una interpretación de carácter adaptativo basada en la motivación y relevancia personal de la información emocional.

Investigating motor imagery tasks by their neural effects - A case study.

Motor imagery, one of the first investigated neural process for Brain-Computer Interfaces (BCIs) still provides a great challenge nowadays. Aiming a better and more accurate control, multiple researches have been conducted by the scientific community. Nevertheless, there is still no robust and confident application developed. In order to augment the potential referring to motor imagery, and to attract user's interest, we propose multiple motor imagery tasks in combination with different visual or auditory stimuli. We use multi-class classification for discrimination and we observe confident classification performance for the task related to user's background.

Maximum entropy based common spatial patterns for motor imagery classification.

The common spatial pattern (CSP) is extensively used to extract discriminative feature from raw Electroencephalography (EEG) signals for motor imagery classification. The CSP is a statistical signal processing technique, which relies on sample based covariance matrix estimation to give discriminative information from raw EEG signals. The sample based estimation of covariance matrix becomes a problem when the number of training samples is limited, which causes the performance of CSP based brain computer interface (BCI) to degrade significantly. In this paper, we present a maximum entropy based CSP algorithm that incorporates principle of maximum entropy while estimating the sample based covariance matrix. The proposed algorithm is evaluated on publicly available data set samples. The classification results indicate that the proposed algorithm outperforms the traditional CSP algorithm by 13.38% on average.

Complexity and familiarity enhance single-trial detectability of imagined movements with electroencephalography.

OBJECTIVE: We sought to determine whether the sensorimotor rhythms (SMR) elicited during motor imagery (MI) of complex and familiar actions could be more reliably detected with electroencephalography (EEG), and subsequently classified on a single-trial basis, than those elicited during relatively simpler imagined actions. METHODS: Groups of healthy volunteers, including experienced pianists and ice hockey players, performed MI of varying complexity and familiarity. Their electroencephalograms were recorded and compared using brain-computer interface (BCI) approaches and spectral analyses. RESULTS: Relative to simple MI, significantly more participants produced classifiable SMR for complex MI. During MI of performance of a complex musical piece, the EEG of the experienced pianists was classified significantly more accurately than during MI of performance of a simpler musical piece. The accuracy of EEG classification was also significantly more sustained during complex MI. CONCLUSION: MI of complex actions results in EEG responses that are more reliably classified for more individuals than MI of relatively simpler actions, and familiarity with actions enhances these responses in some cases. SIGNIFICANCE: The accuracy of SMR-based BCIs in non-communicative patients may be improved by employing familiar and complex actions. Increased sensitivity to MI may also improve diagnostic accuracy for severely brain-injured patients in a vegetative state.

EEG-based motor imagery classification accuracy improves with gradually increased channel number.

The question of how many channels should be sed for classification remains a key issue in the study of Brain-Computer Interface. Several studies have shown that a reduced number of channels can achieve the optimal classification accuracy in the offline analysis of motor imagery paradigm, which does not have real-time feedback as in the online control. However, for the cursor movement control paradigm, it remains unclear as to how many channels should be selected in order to achieve the optimal classification. In the present study, we gradually increased the number of channels, and adopted the time-frequency-spatial synthesized method for left and right motor imagery classification. We compared the effect of increasing channel number in two datasets, an imagery-based cursor movement control dataset and a motor imagery tasks dataset. Our results indicated that for the former dataset, the more channels we used, the higher the accuracy rate was achieved, which is in contrast to the finding in the latter dataset that optimal performance was obtained at a subset number of channels. When gradually increasing the number of channels from 2 to all in the analysis of cursor movement control dataset, the average training and testing accuracies from three subjects improved from 68.7% to 90.4% and 63.7% to 87.7%, respectively.

Motor imagery in physical therapist practice.

Motor imagery is the mental representation of movement without any body movement. Abundant evidence on the positive effects of motor imagery practice on motor performance and learning in athletes, people who are healthy, and people with neurological conditions (eg, stroke, spinal cord injury, Parkinson disease) has been published. The purpose of this update is to synthesize the relevant literature about motor imagery in order to facilitate its integration into physical therapist practice. This update also will discuss visual and kinesthetic motor imagery, factors that modify motor imagery practice, the design of motor imagery protocols, and potential applications of motor imagery.

Imagery content during nonpharmacologic analgesia in the procedure suite: where your patients would rather be.

RATIONALE AND OBJECTIVES: Imagery as a hypnotic technique can produce analgesia and anxiolysis, but effective use may be restricted to select, highly hypnotizable individuals. This study assessed (a) whether patients not selected for hypnotizability can produce imagery during interventional radiologic procedures and (b) the type of imagery produced. A secondary goal of the study was to familiarize health care providers with a simple, time-efficient technique for imagery. MATERIALS AND METHODS: Fifty-six nonselected patients referred for interventional procedures were guided to a state of self-hypnotic relaxation by a health care provider according to a standardized protocol and script. Patient hypnotizability was assessed according to the Hypnotic Induction Profile test. RESULTS: Patients as a group had average distribution of hypnotizability. The induction script was started in all patients and completed in 53. All patients developed an imagery scenario. Chosen imagery was highly individual, but common trends were nature and travel, family and home, and personal skills. Being with loved ones was an important element of imagery for 14 patients. Thirty-two patients chose passive contemplation, and 24 were action oriented. CONCLUSION: Average patients who present for interventional radiologic procedures and are not preselected for hypnotizability can engage in imagery. Topics chosen are highly individual, thus making prerecorded tapes or provider-directed imagery unlikely to be equally successful.