Neurophysiological studies in humans employing magneto- and electro- encephalography increasingly suggest that oscillatory rhythmic activity of the brain may be a core mechanism for binding sensory information across space, time, and object features to generate a unified perceptual representation. To distinguish whether oscillatory activity is causally related to binding processes or whether, on the contrary, it is a mere epiphenomenon, one possibility is to employ neuromodulatory techniques such as transcranial alternating current stimulation. tACS has seen a rising interest due to (...) its ability to modulate brain oscillations in a frequency-dependent manner. In the present review, we critically summarize current tACS evidence for a causal role of oscillatory activity in spatial, temporal, and feature binding in the context of visual perception. For temporal binding, the emerging picture supports a causal link with the power and the frequency of occipital alpha rhythms ; however, there is no consistent evidence on the causal role of the phase of occipital tACS. For feature binding, the only study available showed a modulation by occipital alpha tACS. The majority of studies that successfully modulated oscillatory activity and behavioral performance in spatial binding targeted parietal areas, with the main rhythms causally linked being the theta and beta frequency bands. On the other hand, spatio-temporal binding has been directly modulated by parieto-occipital gamma and alpha tACS, suggesting a potential role of cross-frequency coupling when binding across space and time. Nonetheless, negative or partial results have also been observed, suggesting methodological limitations that should be addressed in future research. Overall, the emerging picture seems to support a causal role of brain oscillations in binding processes and, consequently, a certain degree of plasticity for shaping binding mechanisms in visual perception, which, if proved to have long lasting effects, can find applications in different clinical populations. (shrink)

Mental causation is a predominantly theoretical topic rather than a topic studied in the laboratory. The purpose of this paper is to outline a general approach for studying mental causation by empirical means for philosophers and scientists interested in the topic. The aim is to outline how we can infer mental causation by empirical methods given an unknown solution to the mind-body problem. The approach is based on the principles of causal inference to find causal relations among observed variables used (...) in all branches of science. With these principles, it is possible to estimate the causal effects of mental events: Make an experimental manipulation of a mental event, control confounding variables, and estimate causal effects on the outcome. The caveat is that we cannot separate the causal effects of a mental event from the physical base of the mental event, independent of whether we assume mental events can be reduced to their physical base. A challenge to estimating causal effects of mental events is that measured physical variables, such as electrophysiological potentials from the brain, might reflect processes that are part of “higher-order” phenomena, such as mental events. This means that controlling “downwards” for confounding variables is challenging. It is, however, not impossible. It also means that inferring non-mental causes of action cannot be done by measuring only physical variables alone. Keeping the mind-body problem in mind when designing experiments, it is possible to infer mental causation. (shrink)