The effect of handedness on mental rotation of hands: a systematic review and meta-analysis

Transformation but not generation of motor images is disrupted following stimulation over the left inferior parietal lobe

Motor imagery (MI) involves the generation, maintenance, and transformation of motor images; yet, the neural underpinnings of each stage are not well understood. Here, we investigated the role of the left inferior parietal lobe (IPL) in the stages of MI. Healthy participants (N = 20) engaged in a MI task (making judgments about hands presented on a screen; hand laterality judgment task) over two days. Past literature demonstrates the mental rotation of hands in this task involves implicit MI (i.e., where MI occurs spontaneously in the absence of explicit instructions). During the task, active (Day A; 120% resting motor threshold) or sham (Day B; placebo) neuronavigated transcranial magnetic stimulation (TMS) was applied to the left IPL (location determined from past neuroimaging work) on 50% of trials at 250, 500, or 750ms post-stimulus onset, corresponding to different stages of MI. A/B days were randomized across participants. Linear mixed effects (LME) modelling conducted on reaction time and accuracy revealed that longer reaction times were observed when TMS was delivered at 750ms after trial onset, and more greatly for active vs. sham stimulation. This effect was exacerbated for palm-vs. back-view stimuli and for left vs. right hands. Accuracy overall was decreased for active vs. sham stimulation, and to a greater extent for palm-vs. back-view stimuli. Findings suggest that the left IPL is involved in image transformation. Overall this work informs on the neural underpinnings of the stages of MI.

Degraded Visibility Body-Specifically Affects Mental Rotation

The way we perceive our own body is shaped by our perception. Changes in sensory input, such as visual degradation, can lead to visual-to-motor shifts in the reference frame used to mentally represent the body. While this effect has been demonstrated in mental representation of hands, it is still unknown whether it also affects mental representation of other body parts. To fill this gap, we asked 35 neurotypical participants to perform mental rotation (laterality judgement) of hand, foot, and full-body images, while the images' visibility (figure/background contrast) was manipulated. Visibility deteriorations increased the steepness of the response time (RT) slopes for mental rotation of hand images shown from a less common view (palm) and of foot images from a more common view (dorsum), but not of full-body images from either the common or uncommon views. Suggesting that steeper and flatter RT slopes evoke the activation of a motor- or vision-based cognitive strategy for mental rotation, respectively, we propose that visual deterioration induces body-specific visual-to-motor shifts in mental processing. These findings show that the reliance on visual or motor aspects to mentally represent the body can be modulated by a reduction in sensory input, which changes the employed cognitive strategy.

Slower but more accurate mental rotation performance in aphantasia linked to differences in cognitive strategies

Mental rotation tasks are frequently used as standard measures of mental imagery. However, aphantasia research has brought such use into question. Here, we assessed a large group of individuals who lack visual imagery (aphantasia) on two mental rotation tasks: a three-dimensional block-shape, and a human manikin rotation task. In both tasks, those with aphantasia had slower, but more accurate responses than controls. Both groups demonstrated classic linear increases in response time and error-rate as functions of angular disparity. In the three-dimensional block-shape rotation task, a within-group speed-accuracy trade-off was found in controls, whereas faster individuals in the aphantasia group were also more accurate. Control participants generally favoured using object-based mental rotation strategies, whereas those with aphantasia favoured analytic strategies. These results suggest that visual imagery is not crucial for successful performance in classical mental rotation tasks, as alternative strategies can be effectively utilised in the absence of holistic mental representations.

Handedness effects on imagery of dominant- versus non-dominant-hand movements: An electroencephalographic investigation

Mental representations of our bodies are thought to influence how we interact with our surroundings. We can examine these mental representations through motor imagery, the imagination of movement using scalp EEG recordings. The visual modality of motor imagery emphasises 'seeing' the imagined movement and is associated with increased activity in the alpha rhythm (8-14 Hz) measured over the occipital regions. The kinaesthetic modality emphasises 'feeling' the movement and is associated with decreased activity in the mu rhythm (8-14 Hz) measured over the sensorimotor cortices. These two modalities can be engaged in isolation or together. We recorded EEG activity while 37 participants (17 left-hand dominant) completed an objective hand motor imagery task. Left-handers exhibited significant activity differences between occipital and motor regions only during imagery of right-hand (non-dominant-hand) movements. This difference was primarily driven by less oscillatory activity in the mu rhythm, which may reflect a shift in imagery strategy wherein participants placed more effort into generating the kinaesthetic sensations of non-dominant-hand imagery. Spatial features of 8-14 Hz activity generated from principal component analysis (PCA) provide further support for a strategy shift. Right-handers also exhibited significant differences between alpha and mu activity during imagery of non-dominant movements. However, this difference was not primarily driven by either rhythm, and no differences were observed in the group's PCA results. Together, these findings indicate that individuals imagine movement differently when it involves their dominant versus non-dominant hand, and left-handers may be more flexible in their motor imagery strategies.

Beyond body image: what body schema and motor imagery can tell us about the way patients with anorexia nervosa experience their body

AIM

Recent evidence suggests that the body image disturbance often observed in patients with anorexia nervosa also extends to the body schema. According to the embodiment approach, the body schema is not only involved in motor execution, but also in tasks that only require a mental simulation of a movement such as motor imagery, mental rotation of bodies, and visuospatial perspective-taking. The aim of the present study was to assess the ability of patients with anorexia to mentally simulate movements.

METHODS

The sample included 52 patients with acute anorexia and 62 healthy controls. All participants completed three tests of explicit motor imagery, a mental rotation test and a test of visuospatial perspective-taking.

RESULTS

Patients with anorexia nervosa, with respect to controls, reported greater difficulties in imagining movements according to a first-person perspective, lower accuracy in motor imagery, selective impairment in the mental rotation of human figures, and reduced ability in assuming a different egocentric visuospatial perspective.

CONCLUSION

These results are indicative of a specific alteration in motor imagery in patients with anorexia nervosa. Interestingly, patients' difficulties appear to be limited to those tasks which specifically rely on the body schema, while patients and controls performed similarly in the 3D objects mental rotation task.

Implicit motor imagery performance and cortical activity throughout the menstrual cycle

Studies show that female motor and visuospatial skills are modulated by the menstrual cycle. Implicit motor imagery, meaning the involuntary imagination of movements during a task, involves kinesthetic, visual, and spatial aspects of the corresponding action and can be investigated by using the hand laterality judgment task (HLJT). In this study we aimed to investigate whether implicit motor imagery performance and cortical activity are altered throughout the menstrual cycle, as demonstrated by motor skills in females. Thus, 31 healthy women underwent HLJT during the menstrual, follicular and luteal phases of their menstrual cycles. Right-handed participants had to recognize the laterality (right or left) of hands presented in different views (palm or back) and orientations on a computer screen. Test performance and EEG event-related potentials were analyzed. Participants performed better in the test in the follicular and luteal phases when compared to the menstrual phase, and the accuracy of the test was positively correlated with estradiol levels in the follicular phase. The difference between medial and lateral hand orientations for rotation-related negativity was significant in the medial and left parieto-occipital regions only in the follicular phase. These findings suggest positive modulating action of estradiol in performing implicit motor imagery.

Blots and brains. A note on the centenary of Hermann Rorschach's death

This historical note is a commemorial of Rorschach, the person, and Rorschach the test. Hermann Rorschach died 100 years ago, not quite a year after the publication of his book containing the 10 inkblots. These have reached an iconic status, but the "Rorschach Test" as used in psychiatry, legal organizations and aptitude assessments is not quite what Hermann Rorschach designed it for in the first line. A first section of this article introduces Hermann Rorschach as a man with very broad interests and an inclination to ask cognitive science questions that are still challenging today. A second section provides a critical summary of the fate of the ten inkblots after Rorschach's death - how they conquered the whole world in a time with a pronouced "psychometric attitude", and also how they failed in some attempts to measure personality traits in special populations. A final section focuses on recent research on one particular aspect of a testee's associations to the inkblots: "movement responses", i.e. the perception of implied motion. Here, neural and behavioral correlates have been demonstrated by modern neuroimaging techniques. One study, which set out to validate both the Rorschach as a personality test and the view that the two cerebral hemispheres correspond to divergent "personalities" is also summarized. The viewpoint concludes by suggesting that future work with inkblots should consider Rorschach's original intention to use inkblots to uncover basic laws of perception. Modern applications of computer-generated pseudorandom stimuli (random dot arrays or stochastic noise) would have been embraced by Hermann Rorschach as he appreciated the impact of visual noise for the study of vision and visual cognition.

Is the left/right judgment task performance altered in unilateral carpal tunnel syndrome: And associated with symptom severity?

BACKGROUND

Left/right judgment task performance (LRJT) is impaired in severe neuropathic pain conditions. However, comparison of LRJT performance in patients with carpal tunnel syndrome (CTS) with a control group with similar cognitive functions has not been investigated.

OBJECTIVE

The aim of the study was to compare the LRJT performance of CTS patients with healthy controls and the unaffected side.

METHODS

Seventy-five CTS patients with dominant, right-hand involvement and 75 control subjects were included in the study. The Recognize® tablet application was used for LRJT performance. Tactile acuity (Two-point discrimination) and handgrip strength; pain severity (Visual Analog Scale) and neuropathic component of pain (Pain Detect Questionnaire); symptom severity and functional impact of CTS (Boston CTS Assessment Test) were evaluated. Mixed-design ANOVAs and correlation analyses were used for data analysis.

DESIGN

Cross-sectional study.

RESULTS

Analysis of variance showed that there was no significant effect of side (affected versus unaffected) or group (CTS versus control group) on recognition accuracy or time. Significant group*site interactions were found for the two-point discrimination F (1,148) = 6.388, p = 0.013; and for handgrip strength F (1,148) = 17.552, p < 0.01. A statistically significant negative correlation was found between recognition accuracy and symptom duration and a significant positive correlation was found between recognition accuracy and handgrip strength in CTS patients (r = -0.267, p = 0.020; r = 0.290, p = 0.012).

CONCLUSION

CTS patients recognize the affected side as accurately and quickly as the unaffected side and control group. Further research is needed to clarify the relationship between LRJT performance in the severely affected CTS group.

GOV REGISTRATION NUMBER

NCT04967144 CLINICALTRIALS.

GOV REGISTRATION DATE

19 July 2021.

Does mental rotation emulate motor processes? An electrophysiological study of objects and body parts

Several arguments suggest that motor planning may share embodied neural mechanisms with mental rotation (MR). However, it is not well established whether this overlap occurs regardless of the type of stimulus that is manipulated, in particular manipulable or non-manipulable objects and body parts. We here used high-density electroencephalography (EEG) to examine the cognitive similarity between MR of objects that do not afford specific hand actions (chairs) and bodily stimuli (hands). Participants had identical response options for both types of stimuli, and they gave responses orally in order to prevent possible interference with motor imagery. MR of hands and chairs generated very similar behavioral responses, time-courses and neural sources of evoked-response potentials (ERPs). ERP segmentation analysis revealed distinct time windows during which differential effects of stimulus type and angular disparity were observed. An early period (90-160 ms) differentiated only between stimulus types, and was associated with occipito-temporal activity. A later period (290-330 ms) revealed strong effects of angular disparity, associated with electrical sources in the right angular gyrus and primary motor/somatosensory cortex. These data suggest that spatial transformation processes and motor planning are recruited simultaneously, supporting the involvement of motor emulation processes in MR.

Viewer and object mental rotation in young adults with psychotic disorders

Schizophrenia patients have difficulty with processing visuo-spatial information, which may explain their deficits with considering other people's point-of-view. Processing visuo-spatial information operates on egocentric and allocentric frames of reference. Here, we tested the ability of individuals at different stages of psychotic disorders, specifically ultra-high-risk for psychosis individuals, as well as first-episode psychosis, and chronic schizophrenia patients, to perform a viewer mental rotation task and an object mental rotation task. The two tasks were differentiated only by the instruction given. Healthy individuals and patients with a diagnosis of anxiety/depressive mood disorder served as non-patient and patient controls, respectively. The results show that first-episode psychosis and chronic schizophrenia patients, but not ultra-high-risk individuals, had more errors and longer response times with both mental rotation tasks than the two control groups. In addition, chronic schizophrenia patients had additional difficulty with the object rotation task. The difference in performance between groups and tasks remained significant even after controlling for age, IQ, and antipsychotic medication dose. The results indicate that patients with psychotic disorders have a deficit of mental spatial imagery that include both egocentric and allocentric representations. This deficit may explain the difficulty of these patients with perspective-taking, and inferring other people's point of view, thoughts or intentions which is at the core of the pathogenesis of schizophrenia.

Handedness effects on motor imagery during kinesthetic and visual-motor conditions

Recent studies show that during a simple movement imagery task, the power of sensorimotor rhythms differs according to handedness. However, the effects of motor imagery perspectives on these differences have not been investigated yet. Our study aimed to check how handedness impacts the activity of alpha (8-13 Hz) and beta (15-30 Hz) oscillations during creating a kinesthetic (KMI) or visual-motor (VMI) representation of movement. Forty subjects (20 right-handed and 20 left-handed) who participated in the experiment were tasked with imagining sequential finger movement from a visual or kinesthetic perspective. Both the electroencephalographic (EEG) activity and behavioral correctness of the imagery task performance were measured. After the registration, we used independent component analysis (ICA) on EEG data to localize visual- and motor-related EEG sources of activity shared by both motor imagery conditions. Significant differences were obtained in the visual cortex (the occipital ICs cluster) and the right motor-related area (right parietal ICs cluster). In comparison to right-handers who, regardless of the task, demonstrated the same pattern in the visual area, left-handers obtained higher power in the alpha waves in the VMI task and better performance in this condition. On the other hand, only the right-handed showed different patterns in the alpha waves in the right motor cortex during the KMI condition. The results indicate that left-handers imagine movement differently than right-handers, focusing on visual experience. This provides new empirical evidence on the influence of movement preferences on imagery processes and has possible future implications for research in the area of neurorehabilitation and motor imagery-based brain-computer interfaces (MI-BCIs).