Annick De Paepe

Time causes forgetting from working memory

Although forgetting in the short term is a ubiquitous phenomenon, its exact causes remain undecided. The aim of the present study was to test the temporal decay hypothesis according to which memory traces fade away with time when attention is diverted by concurrent activities. In two experiments involving complex span tasks, adults were asked to remember series of items (either letters or spatial locations) while verifying multiplications. The duration of processing was manipulated by presenting multiplications either in word (three    ×    four    =    twelve) or digit (3    ×    4    =    12) format, the former taking longer to solve, while the time available to restore memory traces after each operation was kept constant across conditions. In line with the temporal decay hypothesis, the longer solution times elicited by solving word multiplications resulted in poorer recall performance. The fact that longer processing times had a comparable effect on both verbal and visuospatial memory and that the difference between conditions remained stable from the first to the last trials makes it difficult to account for these findings by assuming that forgetting is exclusively due to representation-based interference or buildup of proactive interference.

Pain, body, and space: What do patients with complex regional pain syndrome really neglect?

ion System Deficits Frame of reference Limb/side concerned by deficits Body representation Vision Impaired recognition [24], perception of the size [25], and the orientation of the limb [34] ? Affected limb Impaired perception of limb position [17] ? Affected and unaffected limbs Internal imagery Distorted mental images of the limb [16] ? Affected limb Proprioception Trend to somatoparaphrenia [5–7] ? Affected limb Impaired perception of limb position outside of vision [17] ? Affected and unaffected limbs Motor function Hypokinesia and motor neglect [6,7] ? Affected limb Spatial perception Somatosensory Impaired identification of fingers to somatosensory stimulation [4] Egocentric (hand-centered) Affected limb No tactile extinction to double stimulation [4] Egocentric (trunk-centered) — Trend to tactile extinction in temporal order judgment tasks, dependent of the posture [26] Egocentric personal Affected (normal posture) and unaffected (crossed posture) limbs Visual No deficit in line bisection [4] Egocentric peripersonal — Neglect in straight-ahead estimation tasks only in the dark [35,36,38] Egocentric extrapersonal Unaffected side Agnosia for object orientation [31] Allocentric (Deficits according to the horizontal

Mapping nociceptive stimuli in a peripersonal frame of reference: evidence from a temporal order judgment task.

The ability to localize nociceptive stimuli on the body surface is essential for an organism to respond appropriately to potential physical threats. This ability not only requires a representation of the space of the observer׳s body, but also of the external space with respect to their body. Therefore, localizing nociceptive stimuli requires coordinating multiple senses into an integrated frame of reference. The peripersonal frame of reference allows for the coding of the position of somatosensory stimuli on the body surface and the position of stimuli occurring close to the body (e.g., visual stimuli). Intensively studied for touch, this topic has been largely ignored when it comes to nociception. Here, we investigated, using a temporal order judgment task, whether the spatial perception of nociceptive stimuli is coordinated with that of proximal visual stimuli into an integrated representation of peripersonal space. Participants judged which of two nociceptive stimuli, one presented to either hand, had been presented first. Each pair of nociceptive stimuli was preceded by lateralized visual cues presented either unilaterally or bilaterally, and either close to, or far from, the participant׳s body. The perception of nociceptive stimuli was biased in favor of the stimulus delivered on the hand adjacent to the unilateral visual cue, especially when the cue was presented near the participant׳s hand. These results therefore suggest that a peripersonal frame of reference is used to map the position of nociceptive stimuli in multisensory space. We propose that peripersonal space constitutes a kind of margin of safety around the body to alert an organism to possible threats.

From a Somatotopic to a Spatiotopic Frame of Reference for the Localization of Nociceptive Stimuli

To react efficiently to potentially threatening stimuli, we have to be able to localize these stimuli in space. In daily life we are constantly moving so that our limbs can be positioned at the opposite side of space. Therefore, a somatotopic frame of reference is insufficient to localize nociceptive stimuli. Here we investigated whether nociceptive stimuli are mapped into a spatiotopic frame of reference, and more specifically a peripersonal frame of reference, which takes into account the position of the body limbs in external space, as well as the occurrence of external objects presented near the body. Two temporal order judgment (TOJ) experiments were conducted, during which participants had to decide which of two nociceptive stimuli, one applied to either hand, had been presented first while their hands were either uncrossed or crossed over the body midline. The occurrence of the nociceptive stimuli was cued by uninformative visual cues. We found that the visual cues prioritized the perception of nociceptive stimuli applied to the hand laying in the cued side of space, irrespective of posture. Moreover, the influence of the cues was smaller when they were presented far in front of participants’ hands as compared to when they were presented in close proximity. Finally, participants’ temporal sensitivity was reduced by changing posture. These findings are compatible with the existence of a peripersonal frame of reference for the localization of nociceptive stimuli. This allows for the construction of a stable representation of our body and the space closely surrounding our body, enabling a quick and efficient reaction to potential physical threats.

Abnormal proactive and reactive cognitive control during conflict processing in major depression.

According to the Dual Mechanisms of Control framework, cognitive control consists of two complementary components: proactive control refers to anticipatory maintenance of goal-relevant information, whereas reactive control acts as a correction mechanism that is activated when a conflict occurs. Possibly, the well-known diminished inhibitory control in response to negative stimuli in Major Depressive Disorder (MDD) patients stems from a breakdown in proactive control, and/or anomalies in reactive cognitive control. In our study, MDD patients specifically showed increased response latencies when actively inhibiting a dominant response to a sad compared with a happy face. This condition was associated with a longer duration of a dominant ERP topography (800-900 ms poststimulus onset) and a stronger activity in the bilateral dorsal anterior cingulate cortex, reflecting abnormal reactive control when inhibiting attention to a negative stimulus. Moreover, MDD patients showed abnormalities in proactive cognitive control when preparing for the upcoming imperative stimulus (abnormal modulation of the contingent negative variation component), accompanied by more activity in brain regions belonging to the default mode network. All together, deficits to inhibit attention to negative information in MDD might originate from an abnormal use of both proactive resources and reactive control processes.

What’s Coming Near? The Influence of Dynamical Visual Stimuli on Nociceptive Processing

Objects approaching us may pose a threat, and signal the need to initiate defensive behavior. Detecting these objects early is crucial to either avoid the object or prepare for contact most efficiently. This requires the construction of a coherent representation of our body, and the space closely surrounding our body, i.e. the peripersonal space. This study, with 27 healthy volunteers, investigated how the processing of nociceptive stimuli applied to the hand is influenced by dynamical visual stimuli either approaching or receding from the hand. On each trial a visual stimulus was either approaching or receding the participant’s left or right hand. At different temporal delays from the onset of the visual stimulus, a nociceptive stimulus was applied either at the same or the opposite hand, so that it was presented when the visual stimulus was perceived at varying distances from the hand. Participants were asked to respond as fast as possible at which side they perceived a nociceptive stimulus. We found that reaction times were fastest when the visual stimulus appeared near the stimulated hand. Moreover, investigating the influence of the visual stimuli along the continuous spatial range (from near to far) showed that approaching lights had a stronger spatially dependent effect on nociceptive processing, compared to receding lights. These results suggest that the coding of nociceptive information in a peripersonal frame of reference may constitute a safety margin around the body that is designed to protect it from potential physical threat.

Remapping nociceptive stimuli into a peripersonal reference frame is spatially locked to the stimulated limb

ABSTRACT The localization of harmful stimuli approaching our body is essential for survival. Here we investigated whether the mapping of nociceptive stimuli is based on a spatial representation that is anchored to the stimulated limb. In three experiments, we measured the effect of unilateral visual stimuli on the perceived temporal order of nociceptive stimuli, applied to each hand. Crucially, the position of the hands and the visual stimuli was manipulated, so that visual and nociceptive stimuli occurred in an adjacent or non‐adjacent spatial position. Temporal order judgments of nociceptive stimuli were biased in favor of the stimulus applied to the hand most adjacent to the visual stimulus, irrespective to their positions in space. This suggests that the ability to determine the position of a nociceptive stimulus on a specific body area is based on a peripersonal representation of the stimulated limb following it during limb displacement. HIGHLIGHTSThree temporal order judgment tasks with visual cues and nociceptive targets were conducted.Both the position of the visual stimuli and the position of the nociceptive stimuli was manipulated.Visual and nociceptive stimuli occurred in an adjacent or non‐adjacent spatial position.Judgments were biased towards the stimulus applied to the hand most adjacent to the visual stimulus.Nociceptive stimuli are mapped in a reference frame spatially locked to a specific body area.

Watching what’s coming near increases tactile sensitivity: An experimental investigation

During medical examinations, doctors regularly investigate a patients somatosensory system by approaching the patient with a medical device (e.g. Von Frey hairs, algometer) or with their hands. It is assumed that the obtained results reflect the true capacities of the somatosensory system. However, evidence from crossmodal spatial research suggests that sensory experiences in one modality (e.g. touch) can be influenced by concurrent information from other modalities (e.g. vision), especially near the body (i.e. in peripersonal space). Hence, we hypothesized that seeing someone approaching your body could alter tactile sensitivity in that body-part. In the In Vivo Approaching Object (IVAO) paradigm, participants detected and localized threshold-level vibrotactile stimuli administered on the left of right hand (=tactile targets). In Experiment 1, this was always preceded by the experimenter approaching the same (congruent trials) or the other (incongruent trials) hand with a pen (=visual cue). In Experiment 2, a condition was added in which a point further away from the hands (also left vs. right) was approached. Response Accuracy was calculated for congruent and incongruent trials (Experiment 1 & 2) and compared between the close and far condition (Experiment 2). As expected, Response Accuracy was higher in congruent trials compared to incongruent trials, but only near the body. As a result, evidence was found for a crossmodal interaction effect between visual and tactile information in peripersonal space. These results suggest that somatosensory evaluations-both medical or research-based-may be biased by viewing an object approaching the body.

Maternal distress in the context of their child’s type 1 diabetes: exploring the role of adaptive maternal emotion regulation on child outcomes

Abstract Parents of children with Type 1 diabetes (T1D) experience high levels of distress, which may negatively impact child functioning. However, little is known about mechanisms that may buffer the adverse impact of parental distress. The current study explored the possible buffering role of maternal adaptive cognitive emotion regulation (CER) for the relationship between maternal distress and child psychological functioning. Forty-three children with T1D (8–15 years) completed measures assessing trait anxiety and depressive symptoms. Their mothers reported on general distress, illness-related parenting stress, and adaptive CER. Maternal illness-related parenting stress (but not general distress) was significantly associated with child psychological functioning. No buffering role for maternal adaptive CER was observed. As the current study is rather preliminary, future research using other methods to examine maternal adaptive CER, and examining other parental variables that may buffer against the negative impact of parental distress is warranted.

Visual stimuli within peripersonal space prioritize pain

Localizing pain not only requires a simple somatotopic representation of the body, but also knowledge about the limb position (i.e., proprioception), and a visual localization of the pain source in external space. Therefore, nociceptive events are remapped into a multimodal representation of the body and the space nearby (i.e., a peripersonal schema of the body). We investigated the influence of visual cues presented either in peripersonal, or in extrapersonal space on the localization of nociceptive stimuli in a temporal order judgement (TOJ) task. 24 psychology students made TOJs concerning which of two nociceptive stimuli (one applied to each hand) had been presented first (or last). A spatially non-predictive visual cue (i.e., lighting of a LED) preceded (80 ms) the nociceptive stimuli. This cue was presented randomly either on the hand of the participant (in peripersonal space), or 70 cm in front of the hand (in extrapersonal space), and either on the left or on the right side of space. Biases in spatial attention are reflected by the point of subjective simultaneity (PSS). The results revealed that TOJs were more biased towards the visual cue in peripersonal space in comparison with the visual cue in extrapersonal space. This study provides evidence for the crossmodal integration of visual and nociceptive stimuli in a peripersonal schema of the body. Future research with this paradigm will explore crossmodal attention deficits in chronic pain populations.