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Stenner, M.-P.

Publications and source records attributed to Stenner, M.-P..

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The Role of Visual Imagery in Face Recognition and Confidence Revisited: New Evidence from Aphantasia, Sampling Context Effects, and a Meta-Analysis

The absence of voluntary visual imagery, known as aphantasia, offers a unique lens into the role of visual imagery in visual memory processes such as face recognition. While aphantasics often report difficulties, behavioral differences in standard tasks have generally been small. One possibility is that the contribution of visual imagery becomes apparent only when face recognition is especially demanding. We compared age- and gender-matched aphantasics and typical imagers on the more challenging long-form version of the Cambridge Face Memory Test (CFMT+) and on a measure of inverted face recognition. We also included tasks assessing object recognition and face perception. No group differences emerged for face perception or object recognition. By contrast, typical imagers outperformed aphantasics under high visual and mnemonic demands in face recognition in the laboratory cohort, particularly at the highest difficulty level of the CFMT+ and in inverted face recognition. This effect was attenuated or even absent in the online cohort. Drift-diffusion modelling indicated that this discrepancy was primarily driven by reduced response caution in online typical imagers. A meta-analysis of published short-form CFMT studies (total N = 432) revealed a moderate and reliable advantage for typical imagers (hedges g [≤] 0.41). Finally, across cohorts and tasks, aphantasics reported consistently lower subjective confidence, independent of accuracy. Overall, these findings suggest that visual imagery benefits face recognition, and highlight the need for caution in online testing, the predominant approach in aphantasia research.

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A domain-general neural signature of serial order memory across action and perception

Remembering events in the correct order, and generating ordered sequences of actions, are fundamental abilities across species. Behavioral studies, and theoretical work, raise the possibility that the brain represents serial order by a domain-general neural code, following the principle of Competitive Queuing. However, direct neurophysiological evidence for Competitive Queuing exists only in the motor domain. When humans and non-human primates prepare for a series of movements, several of the upcoming movements are represented in parallel, with their representational strength reflecting ordinal position in the sequence. We test the generalizability of this so-called primacy gradient across motor sequences and memorized auditory sequences. Using a multivariate decoding approach, Experiment 1 replicated the presence of a Competitive Queuing primacy gradient in magnetoencephalography (MEG) data of young healthy adults (n = 23) when they prepared a sequence of finger movements from memory. Importantly, we observed a similar primacy gradient when participants anticipated a sequence of tones they had learned before, in the absence of any movement. In Experiment 2 (n = 23; naive cohort), we rule out the possibility that this primacy gradient in auditory memory is explained by any learnt association between tones and movements, or by MEG signal fluctuations that are unrelated to discrete sequential events. In sum, we find a similar neural signature of serial order coding when humans prepare a sequence of movements, and when they anticipate a sequence of sounds. This lends support to the generalizability of Competitive Queuing.

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Flexibility and Neural Correlates of Action-Sound Predictions

To interact efficiently with our environment, our brain predicts the sensory effects of our actions and compares them with the actual outcomes. This allows us to adapt our actions when predictions and sensory outcomes mismatch. While this process is generally well understood for action-sound predictions, it is an open question how flexibly these predictions can adapt in frequently changing environments, as they occur in real life. To investigate the flexibility of top-down predictions, we asked participants (N = 41) to press one of two buttons, a left-hand and a right-hand button, and switch hands autonomously. One button frequently produced a sound (80%) and rarely no sound. The other button frequently generated no sound (80%) and rarely produced a sound. In a third, separate condition, each button produced a sound in 50% of the trials. Unexpected sounds and unexpected sound omissions elicited a series of error-related brain responses in the electroencephalogram (EEG) at different levels of auditory processing, including a mismatch negativity (MMN) and the P3 complex for unexpected sounds, and the oN1, oN2, and oP3 complex for unexpected omissions. Moreover, unexpected sounds elicited an equivalent MMN--regardless of whether silence was expected (80%) or no reliable expectation was possible (50%), while later P3 components showed different amplitudes. Our results demonstrate flexible action-sound predictions at sensory and higher cortical levels. Furthermore, they indicate that predicted silence does not have an explicit sensory representation at lower levels but emerges at later stages, when higher-level information has been integrated.

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Post-movement beta rebound reflects strategic re-aiming during motor adaptation, but not re-aiming accuracy

Motor adaptation results from several interacting learning mechanisms, including learning via cognitive strategies and implicit adaptation. While strategy-based and implicit learning can be dissociated at a behavioural level, their underlying systems-level physiology is poorly understood. A neural signal that undergoes pronounced changes during motor adaptation is the post-movement beta-rebound (PMBR). However, it is unclear how these changes relate to the specific learning mechanisms that contribute to motor adaptation. We measured electroencephalography (EEG) while healthy participants (N=27) performed reaching movements towards a target. In most trials, a cursor showed the veridical position of the unseen hand, however, for some reaches, the direction of the cursor was rotated relative to the position of the hand. Participants were informed that, once a rotation occurred, it could persist for a single trial (1x condition), or for two consecutive trial (2x condition). In the 2x condition, participants could therefore redirect the rotated cursor through the target in the second rotated trial by re-aiming, while they had to continue aiming at the target in the 1x condition. We observed a stronger decrease of PMBR following the first rotated reach in the 2x condition, compared to the 1x condition, despite similar kinematics. This corroborates our previous results that PMBR reflects strategic re-aiming (Korka et al., 2023). However, when we collapsed data from the two studies (total N=53), we found that the degree to which the PMBR decreases does not predict re-aiming accuracy. We discuss the role of PMBR in motor adaptation, including implications for clinical disorders.

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"Micro-offline gains" convey no benefit for motor skill learning

While practising a new motor skill, resting for a few seconds can improve performance immediately after the rest. This improvement has been interpreted as rapid offline learning1,2 ("micro-offline gains", MOG), supported by neural replay of the trained movement sequence during rest3. Here, we provide evidence that MOG reflect transient performance benefits, partially mediated by motor planning, and not replay-mediated offline learning. In five experiments, participants trained to produce a sequence of finger movements as many times as possible during fixed-duration practice periods. When participants trained during 10-second practice periods, each followed by a 10-second rest period, they produced more correct keypresses during training than participants who trained without taking breaks. However, this benefit vanished within seconds after the end of training, when both groups performed under comparable conditions, revealing similar levels of skill acquisition. This challenges the idea that MOG reflect offline learning, which, if present, should result in sustained performance benefits, compared to training without breaks. Furthermore, sequence-specific replay was not necessary for MOG, given that we observed persistent MOG when participants produced random sequences that never repeated, preventing any effect of (sequence-specific) replay on the performance. Importantly, we observed diminished MOG when participants could not pre-plan the first few movements of an upcoming practice period. We conclude that "micro-offline gains" represent short-lived performance benefits that are partially driven by motor pre-planning, rather than replay-mediated offline learning.

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Imprecise perception of hand position during early motor adaptation

Localizing ones body parts is important for movement control and motor learning. Recent studies have shown that the precision with which people localize their hand places constraints on motor adaptation. While these studies have assumed that hand localization remains equally precise across learning, we show that precision decreases rapidly during early motor learning. In three experiments, healthy young participants (n=92) repeatedly adapted to a 45{degrees} visuomotor rotation for a cycle of two to four reaches, followed by a cycle of two to four reaches with veridical feedback. Participants either used an aiming strategy that fully compensated for the rotation (experiment 1), or always aimed directly at the target, so that adaptation was implicit (experiment 2). We omitted visual feedback for the last reach of each cycle, after which participants localized their unseen hand. We observed an increase in the variability of angular localization errors when subjects used a strategy to counter the visuomotor rotation (experiment 1). This decrease in precision was less pronounced in the absence of re-aiming (experiment 2), and when subjects knew that they would have to localize their hand on the upcoming trial, and could thus fully allocate attention to hand position (experiment 3). We propose that attention to vision during strategic re-aiming decreases the precision of perceived hand position. We discuss how these dynamics in precision during early motor learning could impact on motor control, and shape the interplay between implicit and strategy-based motor adaptation. NEW & NOTEWORTHYRecent studies indicate that the precision with which people localize their hand limits implicit visuomotor learning. We found that localization precision is not static, but decreases early during learning. This decrease is pronounced when people apply a re-aiming strategy to compensate for a visuomotor perturbation, and diminishes when the hand is fully attended. We propose that these attention-dependent dynamics in position sense during learning may influence how implicit and strategy-based motor adaption interact.

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Altered Dynamics of Cortical Beta-Oscillations during Motor Learning in Cerebellar Ataxia

Cerebellar ataxia is associated with an implicit motor learning dysfunction, specifically, a miscalibration of internal models relating motor commands to state changes of the body. Explicit cognitive strategies could compensate for deficits in implicit calibration. Surprisingly, however, patients with cerebellar ataxia use insufficient strategies compared to healthy controls. We report a candidate physiological phenomenon of disrupted strategy use in cerebellar ataxia, reflected in an interaction of implicit and explicit learning effects on cortical beta oscillations. We recorded electroencephalography in patients with cerebellar ataxia (n=18), age-matched healthy controls (n=19), and young, healthy individuals (n=34) during a visuomotor rotation paradigm in which an aiming strategy was either explicitly instructed, or had to be discovered through learning. In young, healthy individuals, learning a strategy, but not implicit learning from sensory prediction error alone, decreased the post-movement beta rebound. Disrupted learning from sensory prediction error in patients, on the other hand, unmasked effects of explicit and implicit control that are normally balanced. Specifically, the post-movement beta rebound increased during strategy use when implicit learning was disrupted, i.e., in patients, but not controls. We conclude that a network disturbance due to cerebellar degeneration surfaces in imbalanced cortical beta oscillations normally involved in strategy learning.

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A Visuomotor Model Enhances Human Position Sense

Integrating information from multiple sources reduces uncertainty. Besides sensory input, animals have access to another source of information about their body and the environment, i.e., their own motor commands, which alter the body and environment in a predictable way. Does this predictability reduce perceptual uncertainty, i.e., variance? Participants moved their unseen arm and reported movement endpoint locations. In two conditions, a predictive model of visuomotor contingencies could either be fully formed, and used for this estimation, or remained incomplete. This was achieved through context trials that provided visual endpoint feedback at a predictable vs. unpredictable latency, while carrying identical spatial information. In two experiments, we found that endpoint estimation was less variable when a full, spatiotemporal, model could be formed. Higher perceptual precision was paralleled by enhanced movement accuracy. We conclude that a visuomotor model provides a separate source of information, additional to sensory input, which enhances human position sense.

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