Lasting EEG/MEG aftereffects on human brain oscillations after rhythmic transcranial brain stimulation: Level of control over oscillatory network activity

A number of rhythmic protocols have emerged for non-invasive brain stimulation (NIBS) in humans, including transcranial alternating current stimulation (tACS), oscillatory transcranial direct current stimulation (otDCS) and repetitive (also called rhythmic) transcranial magnetic stimulation (rTMS). With these techniques, it is possible to match the frequency of the externally applied electromagnetic fields to the intrinsic frequency of oscillatory neural population activity ("frequency-tuning"). Mounting evidence suggests that by this means tACS, otDCS, and rTMS can entrain brain oscillations and promote associated functions in a frequency-specific manner, in particular during (i.e. online to) stimulation. Here, we focus instead on the changes in oscillatory brain activity that persist after the end of stimulation. Understanding such aftereffects in healthy participants is an important step for developing these techniques into potentially useful clinical tools for the treatment of specific patient groups. Reviewing the electrophysiological evidence in healthy participants, we find aftereffects on brain oscillations to be a common outcome following tACS/otDCS and rTMS. However, we did not find a consistent, predictable pattern of aftereffects across studies, which is in contrast to the relative homogeneity of reported online effects. This indicates that aftereffects are partially dissociated from online, frequency-specific (entrainment) effects during tACS/otDCS and rTMS. We outline possible accounts and future directions for a better understanding of the link between online entrainment and offline aftereffects, which will be key for developing more targeted interventions into oscillatory brain activity

Prismatic adaptation modulates oscillatory EEG correlates of motor preparation but not visual attention in healthy participants

Prismatic adaption (PA) has been proposed as a tool to induce neural plasticity and is used to help neglect rehabilitation. It leads to a recalibration of visuo-motor coordination during pointing as well as to after-effects on a number of sensorimotor and attention tasks, but whether these effects originate at a motor or attentional level remains a matter of debate. Our aim was to further characterise PA after-effects by using an approach that allows distinguishing between effects on attentional and motor processes. We recorded electroencephalography (EEG) in healthy human participants (9 females and 7 males) while performing a new double step, anticipatory attention/motor preparation paradigm before and after adaptation to rightward shifting prisms, with neutral lenses as a control. We then examined PA after-effects through changes in known oscillatory EEG signatures of spatial attention orienting and motor preparation in the alpha and beta frequency bands. Our results were twofold. First, we found PA to rightward shifting prisms to selectively affect EEG signatures of motor but not attentional processes. More specifically, PA modulated preparatory motor EEG activity over central electrodes in the right hemisphere, contralateral to the PA-induced, compensatory leftward shift in pointing movements. No effects were found on EEG signatures of spatial attention orienting over occipito-parietal sites. Second, we found the PA effect on preparatory motor EEG activity to dominate in the beta frequency band. We conclude that changes to intentional visuo-motor rather than attentional visuo-spatial processes underlie the PA after-effect of rightward deviating prisms in healthy participants

Role of the cerebellum in adaptation to delayed action effects

Actions are typically associated with sensory consequences. For example, knocking at a door results in predictable sounds. These self-initiated sensory stimuli are known to elicit smaller cortical responses compared to passively presented stimuli, e.g., early auditory evoked magnetic fields known as M100 and M200 components are attenuated. Current models implicate the cerebellum in the prediction of the sensory consequences of our actions. However, causal evidence is largely missing. In this study, we introduced a constant delay (of 100 ms) between actions and action-associated sounds, and we recorded magnetoencephalography (MEG) data as participants adapted to the delay. We found an increase in the attenuation of the M100 component over time for self-generated sounds, which indicates cortical adaptation to the introduced delay. In contrast, no change in M200 attenuation was found. Interestingly, disrupting cerebellar activity via transcranial magnetic stimulation (TMS) abolished the adaptation of M100 attenuation, while the M200 attenuation reverses to an M200 enhancement. Our results provide causal evidence for the involvement of the cerebellum in adapting to delayed action effects, and thus in the prediction of the sensory consequences of our actions

Noninvasive brain stimulation techniques can modulate cognitive processing

Recent methods that allow a noninvasive modulation of brain activity are able to modulate human cognitive behavior. Among these methods are transcranial electric stimulation and transcranial magnetic stimulation that both come in multiple variants. A property of both types of brain stimulation is that they modulate brain activity and in turn modulate cognitive behavior. Here, we describe the methods with their assumed neural mechanisms for readers from the economic and social sciences and little prior knowledge of these techniques. Our emphasis is on available protocols and experimental parameters to choose from when designing a study. We also review a selection of recent studies that have successfully applied them in the respective field. We provide short pointers to limitations that need to be considered and refer to the relevant papers where appropriate

Prefrontal control over motor cortex cycles at beta-frequency during movement inhibition

A fully adapted behavior requires maximum efficiency to inhibit processes in the motor domain [ 1 ]. Although a number of cortical and subcortical brain regions have been implicated, converging evidence suggests that activation of right inferior frontal gyrus (r-IFG) and right presupplementary motor area (r-preSMA) is crucial for successful response inhibition [ 2, 3 ]. However, it is still unknown how these prefrontal areas convey the necessary signal to the primary motor cortex (M1), the cortical site where the final motor plan eventually has to be inhibited or executed. On the basis of the widely accepted view that brain oscillations are fundamental for communication between neuronal network elements [ 4–6 ], one would predict that the transmission of these inhibitory signals within the prefrontal-central networks (i.e., r-IFG/M1 and/or r-preSMA/M1) is realized in rapid, periodic bursts coinciding with oscillatory brain activity at a distinct frequency. However, the dynamics of corticocortical effective connectivity has never been directly tested on such timescales. By using double-coil transcranial magnetic stimulation (TMS) and electroencephalography (EEG) [ 7, 8 ], we assessed instantaneous prefrontal-to-motor cortex connectivity in a Go/NoGo paradigm as a function of delay from (Go/NoGo) cue onset. In NoGo trials only, the effects of a conditioning prefrontal TMS pulse on motor cortex excitability cycled at beta frequency, coinciding with a frontocentral beta signature in EEG. This establishes, for the first time, a tight link between effective cortical connectivity and related cortical oscillatory activity, leading to the conclusion that endogenous (top-down) inhibitory motor signals are transmitted in beta bursts in large-scale cortical networks for inhibitory motor control

Governing Emotions. Husserl and Personal Vocation

Husserl’s work contains a central ethical question: the creation of a personal order in relation to values and their cognition. An order in which the fundamental structure of the actual idea of a person is revealed: that of being the essential tie between feeling, motivation of volition and logical-argumentative coherence. This value is felt emotionally but the true understanding of the value only occurs in rational choice, when feeling is concretely translated into value; only when the intellect recognises what has become manifest in emotional acts, does the value actually become such and can act as a motivation for rational action. As its consequent result, the ability of evaluation makes use of the understanding of the meaning of the personal unit: the actual faculty of self-evaluation and selfdetermination, of self-regulation towards the good and right. It is the theme of centrality that the process of self-formation as the education of the self assumes in Husserlian ethical discourse as the capacity to relate the general norm to one’s own order of values, to one’s best, that corresponds to the very question of personal vocation according to Husserl. This is certainly an individual ideal but at the same time, also a social ideal since the actual life of a community can take on the form of an ethical life characterised by collective renewal, but only on the basis of the capacity for individual renewal

Epoché. Husserl e lo scetticismo

According to Husserl there is not only a negative meaning of scepticism, in which reason dissolves itself in an exasperated relativism, but also a completely opposite one, in which the idea of scepticism is a necessary transition for rational argumentation that reflects the actual ability of radically questioning those certainties that are fideistically interwoven in the relationship between life and scientific knowledge. It is therefore equally unquestionable that the objective of such scepticism is to seek, with untiring fatigue, solid, persuasive terrain for one’s own argumentation that has the constant backdrop of revealing a new idea of subjectivity in its intrinsic tie with science and the common world of practical life. These two forms of scepticism, the anti-philosophical and the critical-rational therefore share an important trait: their unavoidable reference to subjectivity. However, whilst the discovery of the absolute intimacy of subjectivity with the world as a theatre of cognitive operations and of the creation of meaning fills the alleged fracture of a reality in itself that transcends the subject, it does not however eliminate the actual reasons of the concrete existence of the world and of the actual influence of such a reality on operations in the process of their creation. It is this that is the crucial question, the essential correlation between self and world, which progressively gains more and more importance in the evolution of Husserl’s notion of epoché and phenomenological reduction. A notion that corresponds to the critical exercise of reason, the necessary exercise of a scepticism that is never exhausted in itself as it never exhausts the view of the constantly changing meaning of the world in the wealth of its infinite essential traits

Note attorno ad alcune aporie del concetto moderno di democrazia

Il concetto di democrazia sembrerebbe possedere un valore universale, un concetto, non solo condivisibile da tutti ma che viene usato spesso, in una sua pretesa purezza, come arma polemica nello scontro tra le parti politiche. In estrema sintesi, tra le maggiori questioni essenziali che nella contemporaneità vengono alla luce rispetto a ciò che chiamiamo democrazia vi sono, elencate in forma non assolutamente esaustiva, le seguenti: la sempre più emergente personalizzazione del potere politico nella figura del leader. Una personalizzazione che emerge di fronte alla crisi radicale delle forme di mediazione tra la vita politica delle istituzioni e i singoli cittadini tipiche della tradizione occidentale, quali il regime parlamentare, i partiti, i sindacati e le associazioni civili. Una situazione complessiva, inoltre, nella quale si va drammaticamente e radicalmente approfondendo la diseguaglianza economica trai i ceti sociali. Si tratta, infine, di un quadro di crisi generale al quale si accompagna, inevitabilmente, una totale carenza di una classe dirigente all’altezza della gestione di tale complessità. Credo, a riguardo, allora, che non sia del tutto inutile, ad una riflessione critico-​politica sul presente, cercare di ripensare la genealogia e le origini stesse del concetto di democrazia. Ci limiteremo naturalmente a mettere in rilievo, nei limiti circoscritti dalle nostre osservazioni, solo alcuni aspetti essenziali della questione, cercando di mostrare alcuni tratti della genesi storica del concetto moderno di democrazia, a nostro giudizio cruciali, nella sostanziale distanza e differenza di tale concetto rispetto all’antichità

Characterizing the cortical oscillatory response to TMS pulse

No abstract available