Effect of the Orientation Difference on Components of Visual Event-Related Potentials

Changes in the components of visual event-related potentials (VERPs) depending on the difficulty of the identification counting tasks (“coarse” and “fine”) were studied in healthy humans. The basic finding is that much greater changes in the VERPs waves were observed within a 5 to 15 deg range than those within the range of 15 to 90 deg. The amplitude of the second sensory component (P2), the latencies of both sensory components, and that of the second cognitive one increased with increase in the task difficulty, while the amplitudes of both cognitive components N2/P3 decreased. Additionally, small changes in the task difficulty affected the attentional effort and modulated the N1 amplitude and P2 latency. These VERP changes are considered an electrophysiological correlate of the psychophysical data when the “label” of an activated orientation-selective channel is sufficient for “coarse” discrimination, and an additional computational process comparing the responses of the activated channels makes discrimination possible in “fine” discrimination.У здорових суб’єктів досліджувалися зміни компонентів візуальних пов’язаних із подією потенціалів (ВППП), залежні від труднощів ідентифікації в завданнях із підрахунком (“грубим” або “тонким”). Основним спостереженням було наступне: в діапазоні 5–15 град відмічалися набагато більші зміни хвиль ВППП порівняно з такими в діапазоні 15–90 град. Амплітуда другого сенсорного компонента (P2), латентні періоди обох сенсорних компонентів і даний параметр другого когнітивного компонента зростали із збільшенням складності завдання, тоді як амплітуди обох когнітивних компонентів N2/P3 зменшувалися. Крім того, невеликі зміни складності завдання впливали на концентрацію уваги і модулювали амплітуду N1 та латентний період P2. Такі зміни ВППП розглядаються як електрографічні кореляти психофізіологічних даних, згідно з якими „мітка” активованого орієнтаційно селективного каналу є достатньою для „грубої” дискримінації, а додатковий процес розрахунків, забезпечуючий порівняння відповідей активованих каналів, робить можливою „тонку” дискримінацію

Sensing with the Motor Cortex

The primary motor cortex is a critical node in the network of brain regions responsible for voluntary motor behavior. It has been less appreciated, however, that the motor cortex exhibits sensory responses in a variety of modalities including vision and somatosensation. We review current work that emphasizes the heterogeneity in sensorimotor responses in the motor cortex and focus on its implications for cortical control of movement as well as for brain-machine interface development

Linking differences in action perception with differences in action execution.

Successful human social interactions depend upon the transmission of verbal and non-verbal signals from one individual to another. Non-verbal social communication is realized through our ability to read and understand information present in other people's actions. It has been proposed that employing the same motor programs, we use to execute an action when observing the same action underlies this action understanding. The main prediction of this framework is that action perception should be strongly correlated with parameters of action execution. Here, we demonstrate that subjects' sensitivity to observed movement speeds is dependent upon how quickly they themselves executed the observed action. This result is consistent with the motor theory of social cognition and suggests that failures in non-verbal social interactions between individuals may in part result from differences in how those individuals move

Gamma band oscillations in parietooccipital areas during performance of a sensorimotor integration task: a qEEG coherence study

This study aimed to elucidate cortical mechanisms involved in anticipatory actions when 23 healthy right-handed subjects had to catch a free falling object through quantitative electroencephalogram (qEEG). For this reason, we used coherence that represents a measurement of linear covariation between two signals in the frequency domain. In addition, we investigated gamma-band (30-100 Hz) activity that is related to cognitive and somatosensory processes. We hypothesized that gamma coherence will be increase in both parietal and occipital areas during moment after ball drop, due to their involvement in manipulation of objects, visuospatial processing, visual perception, stimuli identification and attention processes. We confirmed our hypothesis, an increase in gamma coherence on P3-P4 (t= -2.15; p=0.033) and PZ-OZ (t= -2.16; p=0.034) electrode pairs was verified for a paired t-test. We conclude that to execute tasks involving anticipatory movements (feedforward mechanisms), like our own task, probably, there is no need of a strong participation of visual areas in the process of information organization to manipulate objects and to process visuospatial information regarding the contact hand-object

Bridging a yawning chasm: EEG investigations into the debate concerning the role of the human mirror neuron system in contagious yawning

Ongoing debate in the literature concerns whether there is a link between contagious yawning and the human mirror neuron system (hMNS). One way of examining this issue is with the use of the electroencephalogram (EEG) to measure changes in mu activation during the observation of yawns. Mu oscillations are seen in the alpha bandwidth of the EEG (8-12 Hz) over sensorimotor areas. Previous work has shown that mu suppression is a useful index of hMNS activation and is sensitive to individual differences in empathy. In two experiments, we presented participants with videos of either people yawning or control stimuli. We found greater mu suppression for yawns than for controls over right motor and premotor areas, particularly for those scoring higher on traits of empathy. In a third experiment, auditory recordings of yawns were compared against electronically scrambled versions of the same yawns. We observed greater mu suppression for yawns than for the controls over right lateral premotor areas. Again, these findings were driven by those scoring highly on empathy. The results from these experiments support the notion that the hMNS is involved in contagious yawning, emphasise the link between contagious yawning and empathy, and stress the importance of good control stimuli. © Psychonomic Society, Inc. 2011