The effect of chronic low back pain on tactile suppression during back movements

The aim of the present study was to examine whether tactile suppression, the phenomenon whereby tactile perception is suppressed during movement, would occur in the context of back movements. Of particular interest, it was investigated if tactile suppression in the back would be attenuated in those suffering from chronic low back pain. Individuals with chronic low back pain (N = 30) and a matched control group (N = 24) detected tactile stimuli on three possible locations (back, arm, chest) while performing a back or arm movement, or no movement. We hypothesized that the movements would induce tactile suppression, and that this effect would be largest for low-intense stimuli on the moving body part. We further hypothesized that, during back movements, tactile suppression on the back would be less pronounced in the chronic low back pain group than in the control group. The results showed the expected general tactile suppression effects. The hypothesis of back-specific attenuation of tactile suppression in the chronic low back pain group was not supported. However, back-specific tactile suppression in the chronic low back pain group was less pronounced in those who performed the back movements more slowly.     

Attention and suppression affect tactile perception in reach-to-grasp movements

Reaching with the hand is characterized by a decrease in sensitivity to tactile stimuli presented to the moving hand. Here, we investigated whether tactile suppression can be canceled by attentional orienting. In a first experiment, participants performed a dual-task involving a goal-directed movement paired with the speeded detection of a tactile pulse. The pulse was either delivered to the moving or stationary hand, during movement preparation, execution, or the post-movement phase. Furthermore, stimulation was delivered with equal probability to either hand, or with a higher probability to either the moving or resting hand. The results highlighted faster RTs under conditions of higher probability of stimulation delivery to both moving and resting hands, thus indicating an attentional effect. For the motor preparation period, RTs were faster only at the resting hand under conditions where tactile stimulation was more likely to be delivered there. In a second experiment, a non-speeded perceptual task was used as a secondary task and tactile discrimination thresholds were recorded. Tactile stimulation was delivered concomitantly at both index fingers either in the movement preparation period (both before and after the selection of the movement effector had taken place), in the motor execution period, or, in a control condition, in the time-window of motor execution, but the movement of the hand was restrained. In the preparation period, tactile thresholds were comparable for the two timings of stimulation delivery; i.e., before and after the selection of the movement effector had taken place. These results therefore suggest that shortly prior to, and during, the execution of goal-directed movements, a combined facilitatory and inhibitory influence acts on tactile perception.     

Tactile suppression in goal-directed movement

Sharing numerous characteristics with suppression in the other senses, tactile suppression is a reliable phenomenon that accompanies movement. By investigating the simplest of movements (e.g., finger flexions), early research tried to explain the origins of the phenomenon in terms of motor command generation together with sensory reafference. Here, we review recent research that has delved into (naturalistic) goal-directed movements. In connection with goal-directed movement, tactile suppression is evident as a decrease in behavioural performance measured shortly prior to, and during, movement execution. It is also reflected in a consistent response bias highlighting the (perceptual) uncertainty of the movement. Goal-directed movement supports the forward model and establishes contextual influences as the defining influences on tactile suppression. Depending on the task at hand, people prioritize a certain percept during movement. Future research, we argue, should focus on studying naturalistic movements, or sequences of movements, that share a common meaning or goal.     

Lost in the move? Secondary task performance impairs tactile change detection on the body

Change blindness, the surprising inability of people to detect significant changes between consecutively-presented visual displays, has recently been shown to affect tactile perception as well. Visual change blindness has been observed during saccades and eye blinks, conditions under which people’s awareness of visual information is temporarily suppressed. In the present study, we demonstrate change blindness for suprathreshold tactile stimuli resulting from the execution of a secondary task requiring bodily movement. In Experiment 1, the ability of participants to detect changes between two sequentially-presented vibrotactile patterns delivered on their arms and legs was compared while they performed a secondary task consisting of either the execution of a movement with the right arm toward a visual target or the verbal identification of the target side. The results demonstrated that a motor response gave rise to the largest drop in perceptual sensitivity (as measured by changes in d′) in detecting changes to the tactile display. In Experiment 2, we replicated these results under conditions in which the participants had to detect tactile changes while turning a steering wheel instead. These findings are discussed in terms of the role played by bodily movements, sensory suppression, and higher order information processing in modulating people’s awareness of tactile information across the body surface.     

Mapping temporal constructs: actions reveal that time is a place

Many languages employ metaphors that associate temporal constructs with locations in space (e.g., back in the old days). However, whether such space-time mappings extend beyond the linguistic domain has received little empirical attention. Noting that motor action represents a pathway through which the integration of spatial and temporal information can be revealed, the current work examined the dynamics of hand movements during a time-classification task. Results revealed that when participants were instructed to process information pertaining to the past (or future), their movements were drawn towards the left (or right). This affirms that spatiotemporal processing is grounded in the sensory-motor systems that regulate human movement.     

Adults with probable developmental coordination disorder selectively process early visual,but not tactile information during action preparation. An electrophysiological study

Developmental coordination disorder (DCD) is a neurodevelopmental condition affecting motor coordination in children and adults. Here, EEG signals elicited by visual and tactile stimuli were recorded while adult participants with and without probable DCD (pDCD) performed a motor task. The task cued reaching movements towards a location in visible peripersonal space as well as an area of unseen personal space. Event-related potentials elicited by visual and tactile stimuli revealed that visual processing was strongly affected by movement preparation in the pDCD group, even more than in controls. However, in contrast to the controls, tactile processing in unseen space was unaffected by movement preparation in the pDCD group. The selective use of sensory information from vision and proprioception is fundamental for the adaptive control of movements, and these findings suggest that this is impaired in DCD. Additionally, the pDCD group showed attenuated motor rhythms (beta: 13–30 Hz) over sensorimotor regions following cues to prepare movements towards unseen personal space. The results reveal that individuals with pDCD exhibit differences in the neural mechanisms of spatial selection and action preparation compared to controls, which may underpin the sustained difficulties they experience. These findings provide new insights into the neural mechanisms potentially disrupted in this highly prevalent disorder.     

Assessing the automaticity of the exogenous orienting of tactile attention

We examined whether or not abrupt tactile onsets are capable of exogenously capturing tactile spatial attention when visual spatial attention is focused elsewhere. In experiment 1, we compared performance under dual-task conditions (where participants performed a tactile exogenous cuing task and a rapid serial visual presentation--RSVP--task at the same time) with their performance under single-task conditions (where the participants had to perform only the cuing task, although the RSVP stream was still presented in the background) and to a no-stream condition (where only the cuing task was presented). Tactile cuing was completely suppressed in both the dual-task and single-task conditions, showing that exogenous tactile spatial orienting is modulated by visual-spatial attention, which hence appears to be far from truly automatic. In experiment 2, we demonstrated that the abolishment of exogenous tactile orienting was not caused by the transient presentation of abrupt onset stimuli (letters). These results therefore show that exogenous spatial attentional orienting toward abrupt peripheral tactile stimuli is possible as long as perceptual resources are not depleted by a perceptually demanding (RSVP) task.     

Motor Planning Influences the Perceived Timing of Vibrotactile Stimuli in an Amplitude-Dependent Manner

The authors characterized how motor planning influences temporal order judgment (TOJ) tasks. They examined this by applying vibrotactile stimulation during the planning stages of a bimanual arm movement that would bring the arms into a crossed configuration. The authors have previously shown that planning to cross the arms induces a subjective reversal of spatially defined temporal order judgments that evolves over the course of the planning period. It was unclear, however, whether this effect is modulated by the extent to which the arms would be crossed after movement. The authors examined this issue by having participants plan to move to 4 different targets that would leave the arms in crossed configurations of varying extents. The results demonstrate that even though cutaneous stimuli were applied before the movements, if participants were planning to move into a more crossed configuration, performance on the TOJ task worsened depending on where they were in the planning process. This data suggest the brain uses planning signals to predict sensations from impending movements in a context-dependent manner.     

Effects of motor intention on the perception of somatosensory events: A behavioural and functional magnetic resonance imaging study

The intention to execute a movement can modulate our perception of sensory events, and this modulation is observed ahead of both ocular and upper limb movements. However, theoretical accounts of these effects, and also the empirical data, are often contradictory. Accounts of “active touch”, and the premotor theory of attention, have emphasized how movement intention leads to enhanced perceptual processing at the target of a movement, or on the to-be-moved effector. By contrast, recent theories of motor control emphasize how internal “forward” model (FM) estimates may be used to cancel or attenuate sensory signals that arise as a result of self-generated movements. We used behavioural and functional brain imaging (functional magnetic resonance imaging, fMRI) to investigate how perception of a somatosensory stimulus differed according to whether it was delivered to a hand that was about to execute a reaching movement or the alternative, nonmoving, hand. The results of our study demonstrate that a somatosensory stimulus delivered to a hand that is being prepared for movement is perceived to have occurred later than when that same stimulus is delivered to a nonmoving hand. This result indicates that it takes longer for a tactile stimulus to be detected when it is delivered to a moving limb and may correspond to a change in perceptual threshold. Our behavioural results are paralleled by the results of our fMRI study that demonstrated that there were significantly reduced blood-oxygen-level-dependent (BOLD) responses within the parietal operculum and insula following somatosensory stimulation of the hand being prepared for movement, compared to when an identical stimulus was delivered to a nonmoving hand. These findings are consistent with the prediction of FM accounts of motor control that postulate that central sensory suppression of somatosensation accompanies self-generated limb movements, and with previous reports indicating that effects of sensory suppression are observed in higher order somatosensory regions.     

Effects of motor intention on the perception of somatosensory events: a behavioural and functional magnetic resonance imaging study

The intention to execute a movement can modulate our perception of sensory events, and this modulation is observed ahead of both ocular and upper limb movements. However, theoretical accounts of these effects, and also the empirical data, are often contradictory. Accounts of "active touch", and the premotor theory of attention, have emphasized how movement intention leads to enhanced perceptual processing at the target of a movement, or on the to-be-moved effector. By contrast, recent theories of motor control emphasize how internal "forward" model (FM) estimates may be used to cancel or attenuate sensory signals that arise as a result of self-generated movements. We used behavioural and functional brain imaging (functional magnetic resonance imaging, fMRI) to investigate how perception of a somatosensory stimulus differed according to whether it was delivered to a hand that was about to execute a reaching movement or the alternative, nonmoving, hand. The results of our study demonstrate that a somatosensory stimulus delivered to a hand that is being prepared for movement is perceived to have occurred later than when that same stimulus is delivered to a nonmoving hand. This result indicates that it takes longer for a tactile stimulus to be detected when it is delivered to a moving limb and may correspond to a change in perceptual threshold. Our behavioural results are paralleled by the results of our fMRI study that demonstrated that there were significantly reduced blood-oxygen-level-dependent (BOLD) responses within the parietal operculum and insula following somatosensory stimulation of the hand being prepared for movement, compared to when an identical stimulus was delivered to a nonmoving hand. These findings are consistent with the prediction of FM accounts of motor control that postulate that central sensory suppression of somatosensation accompanies self-generated limb movements, and with previous reports indicating that effects of sensory suppression are observed in higher order somatosensory regions.     

Shifts of spatial attention cued by irrelevant numbers: Electrophysiological evidence from a target discrimination task

Fischer et al. demonstrated that a centrally presented number can shift attention to the left/right when its magnitude is small/large. Two electrophysiological studies described these attentional effects as event-related potentials (ERPs) at centro-parietal sites. Since both studies used target detection tasks, it remains currently unknown whether similar results would be obtained with a discrimination task. We used ERPs to test whether digit cues also induce attention shifts when participants perform a feature-discrimination task on targets. ERPs were recorded whereas subjects discriminated the colour of lateral targets that were preceded by a central non-predictive digit. Analysis of cue-locked controlateral vs. ipsilateral ERP activity showed the emergence of early preparatory attention-directing components in parietal and frontal regions. Moreover, target-locked P1 components at occipito-parietal sites were significantly modulated by digit magnitude-target side congruency. These results demonstrate that irrelevant digit cues also bias sensory processing when embedded in a feature-discrimination task.     

Assessing tactile perception: effects of different visual barriers on performance

Blindfolding candidates when testing their tactile performance may increase their anxiety. This study examined whether different visual barriers would influence tactile performance on timed tasks. It was hypothesised that candidates using a blindfold would be more anxious, but that they would benefit by the potentially positive effects of arousal on performance and not differ from candidates using a screen to limit visual access to task material. 200 participants (ages 19 to 30 years), randomly assigned to the two conditions, completed a tactile perception task, as well as an anxiety scale. In contrast to the expected outcome, the screen sample took significantly longer to complete the task. This was hypothesised to be the result of increased distraction given competing cross-modal attentional demands and the consequent visual and tactile attention switching. Practitioners may need to consider the influences of visual interference when assessing tactile performance.     

Tactile short-term memory for stimuli presented on the fingertips and across the rest of the body surface

The aim of this study was to investigate the extent to which tactile information that is unavailable for full conscious report can be accessed using partial-report procedures. In Experiment 1, participants reported the total number of tactile stimuli (up to six) presented simultaneously to their fingertips (numerosity judgment task). In another condition, after being presented with the tactile display, they had to detect whether or not the position indicated by a (visual or tactile) probe had previously contained a tactile stimulus (partial-report task). Participants correctly reported up to three stimuli in the numerosity judgment task, but their performance was far better in the partial-report task: Up to six stimuli were perceived at the shortest target-probe intervals. A similar pattern of results was observed when the participants performed a concurrent articulatory suppression task (Exp. 2). The results of a final experiment revealed that performance in the partial-report task was overall better for stimuli presented on the fingertips than for stimuli presented across the rest of the body surface. These results demonstrate that tactile information that is unavailable for report in a numerosity task can nevertheless sometimes still be accessed when a partial-report procedure is used instead.     

The distinction between tapping and circle drawing with and without tactile feedback: an examination of the sources of timing variance

An internal clock-like process has been implicated in the control of rhythmic movements performed for short (250-2,000 ms) time scales. However, in the past decade, it has been claimed that a clock-like central timing mechanism is not required for smooth cyclical movements. The distinguishing characteristic delineating clock-like (event) from non-clock-like (emergent) timing is thought to be the kinematic differences between tapping (discrete-like) and circle drawing (smooth). In the archetypal event-timed task (tapping), presence of perceptual events is confounded with the discrete kinematics of movement (table contact). Recently, it has been suggested that discrete perceptual events help participants synchronize with a metronome. However, whether discrete tactile events directly elicit event timing has yet to be determined. In the present study, we examined whether a tactile event inserted into the circle drawing timing task could elicit event timing in a self-paced (continuation) timing task. For a majority of participants, inserting an event into the circle drawing task elicited timing behaviour consistent with the idea that an internal timekeeper was employed (a correlation of circle drawing with tapping). Additionally, some participants exhibited characteristics of event timing in the typically emergently timed circle drawing task. We conclude that the use of event timing can be influenced by the insertion of perceptual events, and it also exhibits persistence over time and over tasks within certain individuals.     

The distinction between tapping and circle drawing with and without tactile feedback: An examination of the sources of timing variance

An internal clock-like process has been implicated in the control of rhythmic movements performed for short (250–2,000 ms) time scales. However, in the past decade, it has been claimed that a clock-like central timing mechanism is not required for smooth cyclical movements. The distinguishing characteristic delineating clock-like (event) from non-clock-like (emergent) timing is thought to be the kinematic differences between tapping (discrete-like) and circle drawing (smooth). In the archetypal event-timed task (tapping), presence of perceptual events is confounded with the discrete kinematics of movement (table contact). Recently, it has been suggested that discrete perceptual events help participants synchronize with a metronome. However, whether discrete tactile events directly elicit event timing has yet to be determined. In the present study, we examined whether a tactile event inserted into the circle drawing timing task could elicit event timing in a self-paced (continuation) timing task. For a majority of participants, inserting an event into the circle drawing task elicited timing behaviour consistent with the idea that an internal timekeeper was employed (a correlation of circle drawing with tapping). Additionally, some participants exhibited characteristics of event timing in the typically emergently timed circle drawing task. We conclude that the use of event timing can be influenced by the insertion of perceptual events, and it also exhibits persistence over time and over tasks within certain individuals.     

Does mental rotation ability depend on sensory-specific experience?

No study has investigated the link between vision and touch with respect to spatial abilities using a within-subjects design. With this design, we compared participants’ tactile and visual mental rotation abilities, as measured by the Mental Rotations Test (Vandenberg & Kuse, 1978). Participants in four groups completed two consecutive sessions under no-switch (visual-visual or tactile-tactile) or switch conditions (visual-tactile or tactile-visual) to determine whether mental rotation abilities assessed in Session 2 depend on previous sensory-specific experiences (Session 1). Analysis of response accuracy revealed that all groups improved their performance in Session 2. Analysis of response time showed an improvement in visual and tactile performance during Session 2 for participants who first performed the task with the same modality. No effect of task repetition appeared for participants who performed in two different sensory conditions. These results reveal that mental rotation ability partly depends on sensory-specific conditions and that ability developed in a sensory-specific condition does not necessarily transfer to another sensory condition.     

Cerebellar contributions to tactile perception in people with varying sensorimotor experiences: Examining the sensory acquisition hypothesis

The sensory acquisition hypothesis states that the sensory demand of a task is the most crucial factor in determining the level of cerebellar activity. The present study was conducted to examine whether the prediction of sensory demand holds when participants have different sensorimotor training experiences. Archery athletes and non-athletic control participants were asked to perform tactile discrimination tasks during fMRI scanning. In archery athletes, a pattern of reduced cerebellar activation accompanying higher sensory cortical activity was observed, whereas in non-athletic control participants the visual network was found to be in concert with extensive cerebellar activation. These findings are in accordance with the prediction that the cerebellum plays a supportive role for the cerebral cortex in sensory data acquisition.     

Attention and movement execution during handwriting

Two studies were performed in order to test the hypothesis that movement execution during handwriting in skilled writers is independent of attention. Study I examined the relationship between attentional functioning and kinematic aspects of handwriting movements in 24 adult participants. A digitizing tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task and various components of their attention were assessed. Correlation analysis indicated no significant relationship between attention functions and both kinematic aspects of handwriting movements and quality of handwriting. In Study II, 20 participants underwent total sleep deprivation (TSD) for 24h. While attention, as assessed with alertness and vigilance tasks, deteriorated during TSD, the execution of handwriting movements, as assessed with a digitizing tablet, improved markedly. The quality of handwriting was not affected by TSD. These findings may suggest an independence between attention and movement generation during handwriting.     

高、低趋近积极情绪对不同注意加工阶段的影响

本研究采用事件相关电位(ERP)技术和Flanker任务, 探讨由甜点和风景图片分别诱发的高、低趋近积极情绪对注意的早期和晚期加工的影响。同时, 为更精细考察情绪对视觉注意范围早期加工阶段的影响, 在75%的Flanker试次中加入了一个白色方块探测刺激, 该刺激位于中央Flanker字母的左侧或右侧。研究结果表明, 在注意加工的早期感知阶段, 高趋近积极情绪下, 带有白色探测刺激的Flanker字母比低趋近积极情绪条件下诱发了更小的P1, 表明高趋近积极情绪窄化了早期注意加工范围; 在注意加工的晚期选择阶段, 高趋近积极情绪下的Flanker字母诱发了更大的N2b成分, 低趋近积极情绪下诱发了更大的P3成分, 表明高趋近积极情绪增强了对干扰的抑制能力, 而低趋近积极情绪下个体调用了更多的注意资源用以加工周边刺激。     

Painful semantic context modulates the relationship between action words and biological movement perception

Studies have revealed a close relationship between action–word processing and the detection of point-light biological movements and that this effect can be modulated by the context of action-verb presentation. The goal of the present study was to further examine the extent to which motor representation activation plays a role in this relationship by testing the influence of painless/painful sentence understanding during a listening task. Participants judged the presence or absence of a point-light biological movement that was embedded in a scrambled mask after a congruent or incongruent action sentence was presented. The sentences varied according to the context of action-verb presentation (painful, painless). Perceptual judgments of human movements improved after a prior presentation of a congruent action sentence but only in the painless context. Thus, our findings show that pain included in a semantic context of sentence presentation can preclude the relationship between action–word understanding and point-light biological movement judgments.