The Control of Event-File Management

Computation on Demand: Action-Specific Representations of Visual Task Features Arise during Distinct Movement Phases

The intention to act influences the computations of various task-relevant features. However, little is known about the time course of these computations. Furthermore, it is commonly held that these computations are governed by conjunctive neural representations of the features. But, support for this view comes from paradigms arbitrarily combining task features and affordances, thus requiring representations in working memory. Therefore, the present study used electroencephalography and a well-rehearsed task with features that afford minimal working memory representations to investigate the temporal evolution of feature representations and their potential integration in the brain. Female and male human participants grasped objects or touched them with a knuckle. Objects had different shapes and were made of heavy or light materials with shape and weight being relevant for grasping, not for "knuckling." Using multivariate analysis showed that representations of object shape were similar for grasping and knuckling. However, only for grasping did early shape representations reactivate at later phases of grasp planning, suggesting that sensorimotor control signals feed back to the early visual cortex. Grasp-specific representations of material/weight only arose during grasp execution after object contact during the load phase. A trend for integrated representations of shape and material also became grasp-specific but only briefly during the movement onset. These results suggest that the brain generates action-specific representations of relevant features as required for the different subcomponents of its action computations. Our results argue against the view that goal-directed actions inevitably join all features of a task into a sustained and unified neural representation.

Instructed speed and accuracy affect binding

In the past few decades, binding and retrieval mechanisms have gained increased interest in research on human action control. Recent studies show that these mechanisms also play a role in the control of multiple independent actions. Here, two or more successively executed responses seem to be bound to each other so that repeating one of them can retrieve the other, affecting performance in this second response and resulting in so-called response-response binding effects. Binding effects are typically found in the response time data and, somewhat less reliably, also in the error rates. Whether binding effects show in the response times, the error rates, or both, is likely influenced by the current speed-accuracy settings of the participants, with binding effects more likely showing in error rates under a speed setting, while more likely showing in RTs under an accuracy setting. Alternatively, different speed-accuracy settings might also entail changes in executive control, affecting the size of observed binding effects. In this study, we tested these assumptions by comparing binding effects under different speed-accuracy settings that were induced via instructions focusing on speed, accuracy, or both (ambivalent). Binding effects were observed in response times independent of instructions, while in error rates, they only showed under speed or ambivalent instructions. These findings indicate that binding effects can be affected by instructions regarding speed and accuracy.

Separated hands further response-response binding effects

Action control is hierarchically organized. Multiple consecutive responses can be integrated into an event representation of higher order and can retrieve each other upon repetition, resulting in so-called response-response binding effects. Previous research indicates that the spatial separation of responses can affect how easily they can be cognitively separated. In this study, we introduced a barrier between the responding hands to investigate whether the spatial separation of two responses also influences response-response binding effects. In line with previous research on stimulus-response binding, we expected an increased separability of responses to result in stronger response-response binding effects when responding hands were separated by a barrier. We indeed found stronger response-response binding effects with separated hands. Results indicate that a more distinct representation of individual actions through increased separability might benefit the control of hierarchical actions.

Imagined object files: Visual imagery produces partial repetition costs where perception does not

The present study explored whether object (or event) files can be formed that integrate color imagery and perceptual location features. To assess this issue, a cue-target procedure was used whereby color imagery was cued to be generated at a particular location in space, which was then followed by a perceptual color discrimination task. Partial repetition costs (PRCs) were then measured by varying the overlap of the color and location features of the cue and target to evaluate whether an object/event file was formed. Robust PRCs were observed when imagery was generated at a location, supporting the idea that imagery and perception can be incorporated into a common event file. It was also revealed that the PRC effects for perceptual color cues were tenuous-they did not reach significance in the present study. Overall, the present study indicates that imagery can produce stronger binding effects than perception, offering important insights into the role that active engagement plays in the formation of object/event files.

Sensorimotor memories influence movement kinematics but not associated tactile processing

When interacting with objects, we often rely on visual information. However, vision is not always the most reliable sense for determining relevant object properties. For example, when the mass distribution of an object cannot be inferred visually, humans may rely on predictions about the object's dynamics. Such predictions may not only influence motor behavior but also associated processing of movement-related afferent information, leading to reduced tactile sensitivity during movement. We examined whether predictions based on sensorimotor memories influence grasping kinematics and associated tactile processing. Participants lifted an object of unknown mass distribution and reported whether they detected a tactile stimulus on their grasping hand during the lift. In Experiment 1, the mass distribution could change from trial to trial, whereas in Experiment 2, we intermingled longer with shorter parts of constant and variable mass distributions, while also providing implicit or explicit information about the trial structure. In both experiments, participants grasped the object by predictively choosing contact points that would compensate the mass distribution experienced in the previous trial. Tactile suppression during movement, however, was invariant across conditions. These results suggest that predictions based on sensorimotor memories can influence movement kinematics but not associated tactile perception.

Effect-less? Event-files are not terminated by distal action effects

Event-files that bind features of stimuli, responses, and action effects figure prominently in contemporary views of action control. When a previous feature repeats, a previous event-file is retrieved and can influence current performance. It is unclear, however, what terminates an event-file. A tacit assumption is that registering the distal (e.g., visual or auditory) sensory consequences of an action (i.e., the "action effect") terminates the event-file, thereby making it available for retrieval. We tested three different action-effect conditions (no distal action effect, visual action effect, or auditory action effect) in the same stimulus-response (S-R) binding task and observed no modulation of S-R binding effects. Instead, there were comparably large binding effects in all conditions. This suggests that proximal (e.g., somatosensory, proprioceptive) action effects terminate event-files independent of distal (e.g., visual, auditory) action effects or that the role event-file termination plays for S-R binding effects needs to be corrected. We conclude that current views of action control require further specification.

Optogenetic stimulation of the primary visual cortex drives activity in the visual association cortex

Developing optogenetic methods for research in non-human primates (NHP) is important for translational neuroscience and for delineating brain function with unprecedented specificity. Here we assess, in macaque monkeys, the selectivity by which optogenetic stimulation of the primary visual cortex (V1) drives the local laminar and widespread cortical connectivity related to visual perception. Towards this end, we transfected neurons with light-sensitive channelrhodopsin in dorsal V1. fMRI revealed that optogenetic stimulation of V1 using blue light at 40 Hz increased functional activity in the visual association cortex, including areas V2/V3, V4, motion-sensitive area MT and frontal eye fields, although nonspecific heating and eye movement contributions to this effect could not be ruled out. Neurophysiology and immunohistochemistry analyses confirmed optogenetic modulation of spiking activity and opsin expression with the strongest expression in layer 4-B in V1. Stimulating this pathway during a perceptual decision task effectively elicited a phosphene percept in the receptive field of the stimulated neurons in one monkey. Taken together, our findings demonstrate the great potential of optogenetic methods to drive the large-scale cortical circuits of the primate brain with high functional and spatial specificity.

Core Mechanisms in Action Control: Binding and Retrieval

This special collection focuses on action control and its two postulated core processes, namely feature binding and retrieval. Action control is an important topic as humans interact with their environment by means of goal-directed behavior, i.e. by means of actions. Cognitive processes were developed and shaped to enhance preparation, execution, and regulation of action. Therefore, it is the current consensus that cognition serves action. To date, research on human action control is comprised mainly of an abundance of paradigm-specific results and models. To gain a better understanding of action control, an integrative framework was proposed (the BRAC framework - for Binding and Retrieval in Action Control, Frings et al., 2020) that can explain a wide range of findings across different experimental paradigms by assuming two core processes as key functions in action control: feature binding and feature retrieval. In this special collection, 20 articles present and discuss different types of sequential paradigms in terms of this integrative account. This editorial explains the major assumptions of the BRAC framework and provides an integrative overview of the articles that are included in this special collection.

Predictability reduces event file retrieval

There is growing consensus that stimulus-response bindings (event files) play a central role in human action control. Here, we investigated how the integration and the retrieval of event files are affected by the predictability of stimulus components of event files. We used the distractor-response binding paradigm, in which nominally task-irrelevant distractors are repeated or alternated from a prime to a probe display. The typical outcome of these kinds of tasks is that the effects of distractor repetition and response repetition interact: Performance is worse if the distractor repeats but the response does not, or vice versa. This partial-repetition effect was reduced when the distractor was highly predictable (Experiment 1). Separate manipulations of distractor predictability in the prime and probe trial revealed that this pattern was only replicated if the probe distractors were predictable (Experiment 2b, 3), but not if prime distractors were predictable (Experiment 2a). This suggests that stimulus predictability does not affect the integration of distractor information into event files, but the retrieval of these files when one or more of the integrated features are repeated. We take our findings to support theoretical claims that integration and retrieval of event files might differ concerning their sensitivity to top-down factors.

What Belongs Together Retrieves Together – The Role of Perceptual Grouping in Stimulus-Response Binding and Retrieval

Nowadays there is consensus that stimulus and response features are partially represented in the same coding format furthering the binding of these features into event files. If some or all features comprised in an event file repeat later, the whole file can be retrieved thereby modulating ongoing performance (leading to so-called stimulus-response binding effects). Stimulus-response binding effects are usually investigated in sequential priming paradigms where it is assumed that binding occurs in the prime and retrieval in the probe. Importantly, binding and retrieval are not exclusive for targets but also apply to distractor stimuli. A previous study showed that distractor-binding effects were affected by perceptual grouping: Binding effects were significantly larger when stimuli were grouped compared to ungrouped stimuli. Recent theorizing suggests that binding and retrieval are two separate processes that can be individually modulated. Against this background, it is not possible to pinpoint the modulating influence of perceptual grouping on either process at this point in time. Therefore, we adapted the previous study design in two experiments to observe the effect of perceptual grouping on both processes in isolation. Results indicate that perceptual grouping did not impact binding but retrieval: Distractor-response retrieval was reduced when target and distractor were presented in separate objects. Our results thus support recent theorizing on the separation of binding and retrieval.