Elisa Filevich

Negative motor phenomena in cortical stimulation: implications for inhibitory control of human action

Electrical stimulation of the human cortex typically elicits positive sensorimotor effects. However, many neurosurgical studies have also reported negative motor areas (NMAs) in which stimulation produces inhibition of ongoing movement. The neurocognitive implications of these studies have not been systematically explored. Here we review the neurosurgical literature on NMAs and link this to cognitive mechanisms of inhibition and their role in voluntary control of action. In particular, we discuss the functional validity of NMAs. We contest the sceptical view that negative effects following stimulation merely reflect disruption of positive motor areas. Instead, we suggest that NMAs may produce an inhibitory mechanism under ecologically valid conditions.

There is no free won't: antecedent brain activity predicts decisions to inhibit.

Inhibition of prepotent action is an important aspect of self-control, particularly in social contexts. Action inhibition and its neural bases have been extensively studied. However, the neural precursors of free decisions to inhibit have hardly been studied. We asked participants to freely choose to either make a rapid key press in response to a visual cue, or to transiently inhibit action, and briefly delay responding. The task required a behavioural response on each trial, so trials involving inhibition could be distinguished from those without inhibition as those showing slower reaction times. We used this criterion to classify free-choice trials as either rapid or inhibited/delayed. For 13 participants, we measured the mean amplitude of the ERP activity at electrode Cz in three subsequent 50 ms time windows prior to the onset of the signal that either instructed to respond or inhibit, or gave participants a free choice. In two of these 50 ms time windows (−150 to −100, and −100 to −50 ms relative to action onset), the amplitude of prestimulus ERP differed between trials where participants ”freely” chose whether to inhibit or to respond rapidly. Larger prestimulus ERP amplitudes were associated with trials in which participants decided to act rapidly as compared to trials in which they decided to delay their responses. Last-moment decisions to inhibit or delay may depend on unconscious preparatory neural activity.

Brain correlates of subjective freedom of choice.

The subjective feeling of free choice is an important feature of human experience. Experimental tasks have typically studied free choice by contrasting free and instructed selection of response alternatives. These tasks have been criticised, and it remains unclear how they relate to the subjective feeling of freely choosing. We replicated previous findings of the fMRI correlates of free choice, defined objectively. We introduced a novel task in which participants could experience and report a graded sense of free choice. BOLD responses for conditions subjectively experienced as free identified a postcentral area distinct from the areas typically considered to be involved in free action. Thus, the brain correlates of subjective feeling of free action were not directly related to any established brain correlates of objectively-defined free action. Our results call into question traditional assumptions about the relation between subjective experience of choosing and activity in the brain’s so-called voluntary motor areas.

Resting-state fMRI correlations: From link-wise unreliability to whole brain stability

&NA; The functional architecture of spontaneous BOLD fluctuations has been characterized in detail by numerous studies, demonstrating its potential relevance as a biomarker. However, the systematic investigation of its consistency is still in its infancy. Here, we analyze within‐ and between‐subject variability and test‐retest reliability of resting‐state functional connectivity (FC) in a unique data set comprising multiple fMRI scans (42) from 5 subjects, and 50 single scans from 50 subjects. We adopt a statistical framework that enables us to identify different sources of variability in FC. We show that the low reliability of single links can be significantly improved by using multiple scans per subject. Moreover, in contrast to earlier studies, we show that spatial heterogeneity in FC reliability is not significant. Finally, we demonstrate that despite the low reliability of individual links, the information carried by the whole‐brain FC matrix is robust and can be used as a functional fingerprint to identify individual subjects from the population.

Metacognitive mechanisms underlying lucid dreaming

Lucid dreaming is a state of awareness that one is dreaming, without leaving the sleep state. Dream reports show that self-reflection and volitional control are more pronounced in lucid compared with nonlucid dreams. Mostly on these grounds, lucid dreaming has been associated with metacognition. However, the link to lucid dreaming at the neural level has not yet been explored. We sought for relationships between the neural correlates of lucid dreaming and thought monitoring. Human participants completed a questionnaire assessing lucid dreaming ability, and underwent structural and functional MRI. We split participants based on their reported dream lucidity. Participants in the high-lucidity group showed greater gray matter volume in the frontopolar cortex (BA9/10) compared with those in the low-lucidity group. Further, differences in brain structure were mirrored by differences in brain function. The BA9/10 regions identified through structural analyses showed increases in blood oxygen level-dependent signal during thought monitoring in both groups, and more strongly in the high-lucidity group. Our results reveal shared neural systems between lucid dreaming and metacognitive function, in particular in the domain of thought monitoring. This finding contributes to our understanding of the mechanisms enabling higher-order consciousness in dreams.

Just another tool for online studies (JATOS): An easy solution for setup and management of web servers supporting online studies

We present here “Just Another Tool for Online Studies” (JATOS): an open source, cross-platform web application with a graphical user interface (GUI) that greatly simplifies setting up and communicating with a web server to host online studies that are written in JavaScript. JATOS is easy to install in all three major platforms (Microsoft Windows, Mac OS X, and Linux), and seamlessly pairs with a database for secure data storage. It can be installed on a server or locally, allowing researchers to try the application and feasibility of their studies within a browser environment, before engaging in setting up a server. All communication with the JATOS server takes place via a GUI (with no need to use a command line interface), making JATOS an especially accessible tool for researchers without a strong IT background. We describe JATOS’ main features and implementation and provide a detailed tutorial along with example studies to help interested researchers to set up their online studies. JATOS can be found under the Internet address: www.jatos.org.

What is the Human Sense of Agency, and is it Metacognitive?

Agency refers to an individual’s capacity to initiate and perform actions, and thus to bring about change, both in their own state, and in the state of the outside world. The importance of agency in human life cannot be understated. Social responsibility is built on the principle that there are “facts” of agency, on which individuals can generally agree. At the individual level, the experience of agency is considered a crucial part of normal mental life. Abnormal sense of agency (SoA)—such as in the well-documented “delusion of control”—is recognised as one of the key symptoms of mental disorders. Yet, beyond abnormalities of control that pertain to psychiatric conditions, normal SoA can be easily fooled. Errors in agency attribution and agency experience have received much attention in recent experimental literature. In everyday life, coincidental conjunctions between our actions and external events commonly occur. The fact that the SoA can be over or underestimated, or that judgements of agency can be wrong, testifies to a significant gap between what individuals think or believe their control capabilities are, and what these capabilities really are. The ability to experience these computations as the causes driving and shaping our actions may account for our ability to correct our behaviours when, precisely, they seem to escape our control. In this sense, any reliable theory about human agency must explain how we can sometimes be deluded about our own agency, but also must account for why we are not deluded all the time. In this chapter, we first identify which signals may contribute to an SoA, and how they might be integrated. We will ask whether human cognition of agency is best analysed as an experience or as an inference. We evaluate the existing data in relation to two contrasting accounts for agency, namely prospective versus purely retrospective approaches. We draw on two major classes of data throughout: psychological data that aims to capture the experience of agency, and physiological data that aims to identify the neural basis of this experience. Finally, we will consider whether the human SoA should really be called ‘metacognitive’. In particular, we directly compare key features of metacognition of agency with perceptual metacognition.

Persistence of Internal Representations of Alternative Voluntary Actions

We have investigated a situation in which externally available response alternatives and their internal representations could be dissociated, by suddenly removing some action alternatives from the response space during the interval between the free selection and the execution of a voluntary action. Choice reaction times in this situation were related to the number of initially available response alternatives, rather than to the number of alternatives available effectively available after the change in the external environment. The internal representations of response alternatives appeared to persist after external changes actually made the corresponding action unavailable. This suggests a surprising dynamics of voluntary action representations: counterfactual response alternatives persist, and may even be actively maintained, even when they are not available in reality. Our results highlight a representational basis for the counterfactual course of action. Such representations may play a key role in feelings of regret, disappointment, or frustration. These feelings all involve persistent representation of counterfactual response alternatives that may not actually be available in the environment.

Behavioural, modeling, and electrophysiological evidence for supramodality in human metacognition

Human metacognition, or the capacity to introspect on ones own mental states, has been mostly characterized through confidence reports in visual tasks. A pressing question is to what extent results from visual studies generalize to other domains. Answering this question allows determining whether metacognition operates through shared, supramodal mechanisms or through idiosyncratic, modality-specific mechanisms. Here, we report three new lines of evidence for decisional and postdecisional mechanisms arguing for the supramodality of metacognition. First, metacognitive efficiency correlated among auditory, tactile, visual, and audiovisual tasks. Second, confidence in an audiovisual task was best modeled using supramodal formats based on integrated representations of auditory and visual signals. Third, confidence in correct responses involved similar electrophysiological markers for visual and audiovisual tasks that are associated with motor preparation preceding the perceptual judgment. We conclude that the supramodality of metacognition relies on supramodal confidence estimates and decisional signals that are shared across sensory modalities. SIGNIFICANCE STATEMENT Metacognitive monitoring is the capacity to access, report, and regulate ones own mental states. In perception, this allows rating our confidence in what we have seen, heard, or touched. Although metacognitive monitoring can operate on different cognitive domains, we ignore whether it involves a single supramodal mechanism common to multiple cognitive domains or modality-specific mechanisms idiosyncratic to each domain. Here, we bring evidence in favor of the supramodality hypothesis by showing that participants with high metacognitive performance in one modality are likely to perform well in other modalities. Based on computational modeling and electrophysiology, we propose that supramodality can be explained by the existence of supramodal confidence estimates and by the influence of decisional cues on confidence estimates.

Grin and bear it! Neural consequences of a voluntary decision to act or inhibit action

Action inhibition is an important part of everyday human behaviour. Most previous studies of action inhibition have focussed on stop-signals. Here, we consider the case where participants themselves decide to inhibit, or not inhibit, a prepotent action. Participants received electric stimulation that elicited an itchy feeling on the wrist. If they made a hand withdrawal movement, this would interrupt the stimulation, and halt the itch. In a factorial design, participants were given external instructions to withdraw their hand when they felt the itch, or to inhibit the natural withdrawal response, and bear the itch. In another condition, they were asked to internally choose between withdrawal and inhibition of withdrawal. Event-related potentials revealed differences between processing of the sensory consequences of internally decided and externally–instructed action and inhibition decisions. Specifically, potentials evoked by itchy stimuli were enhanced in internally decided inhibition trials, as compared to externally instructed inhibition trials. In contrast, processing of itchy stimuli was reduced in internally decided action trials, as compared to externally instructed action trials. These results show that internal decisions lead to different perceptual processing of the consequences of action and inhibition and suggest that features of decision processes can be measured via their consequences.