Body Context and Posture Affect Mental Imagery of Hands (original) (raw)
Related papers
The influence of hands posture on mental rotation of hands and feet
Experimental Brain Research, 2007
Behavioural and functional neuroanatomy studies demonstrate that mental rotation of body parts is carried out through a sort of inner motor simulation. Here we examined whether changes of hands posture influence the mental rotation of hands and feet. Twenty healthy subjects were asked to verbally judge the laterality of hands and feet pictures in two different postural conditions. In one condition, subjects kept hands on their knees in anatomical position; in the other, their hands were kept in an unusual posture with intertwined fingers, behind the back. Results show that mental rotation of hands but not of feet was influenced by changes in hands posture. Indeed, while mental rotation of hands was faster in the front than in the back hands position, no similar effect was found when mentally rotating feet. Thus, sensory-motor and postural information coming from the body may influence mental rotation of body parts according to specific, somatotopic rules.
Experimental Brain Research, 2009
The representation of the body in the brain is continuously updated with regard to peripheral factors such as position or movement of body parts. In the present study, we investigated the eVects of arm posture on the mental rotation of hands and feet. Sixteen right-handed and ten left-handed participants verbally judged the laterality of visually presented pictures of hands and feet in two diVerent postural conditions. In one condition they placed their right hand on their right knee and their left hand behind the back, in the other condition the hand position was reversed. For right-handed participants response times for the laterality judgment of right hands increased when participants kept their right hand behind the back. This was not found for images of the left hand nor for images of the feet. For the left-handed participants, there was no eVect of arm posture on hand or feet stimulus judgments. Thus, the body-part posture eVect on mental rotation was found to be speciWc for the side and the body part for which the posture was modiWed only in right-handed participants, but it was absent for left-handed participants. For both samples, we also found a progressive disruption of the mental rotation function depending on the view from which the body parts were seen (i.e. dorsal, thumb/big toe, palm/plantar, little Wnger/toe). Posture and view eVects on body parts representations are discussed with respect to proprioception, handedness, visual familiarity and the inXuence of anatomical joint constraints on motor imagery.
Experimental Brain Research, 2019
Left/right judgement (LRJ) tasks involve determining the laterality of presented hand or feet images. Allocentric images (third-person perspective; 3PP) take longer to identify than egocentric images (first-person perspective; 1PP), supporting that implicit motor imagery (IMI)-mentally manoeuvring one's body to match the shown posture-is used. While numerous cognitive processes are involved during LRJs, it remains unclear whether features of the individual (e.g., visual exposure, experience, task-dependent use) influence the type of recognition strategy used during LRJs (IMI versus non-IMI). To investigate whether an individual's routine visual exposure to hands/feet in 3PP disrupts the typical perspective-reaction time (RT) relationship in LRJs, hand therapists, podiatrists, and healthy controls completed online LRJ tasks of hand and feet images. A group-specific reduction in RT for only allocentric images would represent a switch to non-IMI strategies. The results show that routine visual exposure to feet in 3PP (podiatrists) results in quicker RTs only for allocentric images of feet, suggesting a switch from IMI to non-IMI (e.g., visual object-based recognition) strategies. In contrast, routine visual exposure to hands in 3PP (hand therapists) does not alter RT for allocentric images, suggesting maintenance of IMI. However, hand therapists have quicker RTs (vs other groups) for egocentric hand images, supporting enhanced sensorimotor processing for the hand, consistent with task-dependent use (precise hand use). Higher accuracy in health professionals (vs control) on both tasks supports enhanced body schema. Combined, this suggests that 3PP visual exposure to body parts and task-dependent use contribute to LRJ performance/recognition strategy.
Anatomically plausible illusory posture affects mental rotation of body parts
Cognitive, Affective, & Behavioral Neuroscience, 2013
During mental rotation (MR) of body parts, people internally simulate the movement of their corresponding body segments. These sensory-motor mechanisms render MR sensitive to proprioceptive information (e.g., posture). Similar mechanisms can alter illusory hand ownership following synchronous visuotactile stimulation (e.g., the rubber hand illusion [RHI]). In the present study, we first showed that illusory ownership for a fake hand can also be induced when the posture of the fake hand (palm-up) does not correspond with the subject's physical hand posture (palm-down). Then we tested whether illusory ownership for a fake hand in such a posture impacts the MR of hands carried out immediately and repeatedly after the RHI. The results showed that MR was altered for the view corresponding to the fake hand's posture, but not for other views. Additionally, these effects depended on illusory ownership, as only synchronous visuotactile stimulation was found to lead to these changes, characterized by a modulation of the rotation-dependent profile of MR response times. These findings show that similar sensory-motor mechanisms are recruited during the MR of hands and illusory hand ownership manipulated through multisensory mismatch, and that bottom-up visuotactile stimulation interferes with highlevel imagery processes.
Hand posture and motor imagery: a body part recognition study
Objective: Recognition of body parts activates specifi c somatosensory representations in a way that is similar to motor imagery. These representations are implicitly activated to compare the body with the stimulus. In the present study, we investigate the infl uence of proprioceptive information relating to body posture on the recognition of body parts (hands). It proposes that this task could be used for rehabilitation of neurological patients. Methods: Ten right-handed volunteers participated in this experiment. The task was to recognize the handedness of drawings of a hand that were presented in different perspectives and several orientations. For drawings of a right hand, the volunteers pressed the right key, and for drawings of a left hand, they pressed the left key. The volunteers underwent two sessions: one with their hands in a prone posture and the other with their hands in a supine posture. Results: The manual reaction time was longer for perspectives and orientations for which the real movement was diffi cult to achieve. This showed that, during the task, motor representations were activated to compare the body with the stimulus. Furthermore, the subject’s posture had an infl uence in relation to specifi c perspectives and orientations. Conclusions: These results showed that motor representations are activated to compare the body with the stimulus, and that the position of the hand infl uences this resonance between the stimulus and the body part.
Does thumb posture influence the mental rotation of hands?
Neuroscience Letters, 2013
We tested the effect of thumb posture in a hand laterality judgement task. Thumb posture was modified in the stimulus pictures and for participants' hands. Effect of stimulus thumb posture occurred only when participants' thumbs were fixed. In palmar view, RTs for 90 • orientations were influenced by biomechanical constraints.
Perceptual and motor mechanisms for mental rotation of human hands
Neuroreport, 2001
We measured brain potentials from human subjects performing a mental rotation task requiring right-left judgments of misoriented hands, and a control task requiring palm-back judgments of the same stimuli. High-density, 128-channel event-related potentials (ERPs) were recorded from 16 normal, right-handed subjects. There was a main effect of task at ®ve different latencies: 148 ms (occipital), 180 ms (parietal), 388 ms (vertex), 556 ms (central-parietal), and 900 ms (vertex). Source estimations derived from topographic data indicate that frontal brain regions were strongly activated after 300 ms in the control task, but not until about 900 ms in the rotation task. We conclude that the neural computations underlying mental hand rotation may be recruited from relatively early stages of visuo-perceptual analysis; these early computations in¯uence subsequent processing within a parietal-prefrontal system for the integration of perception with action. NeuroReport 12:3433± 3437
Allocentric visual cues influence mental transformation of bodies
Journal of vision, 2013
Identifying a human body stimulus involves mentally rotating an embodied spatial representation of one's body (motoric embodiment) and projecting it onto the stimulus (spatial embodiment). Interactions between these two processes (spatial and motoric embodiment) may thus reveal cues about the underlying reference frames. The allocentric visual reference frame, and hence the perceived orientation of the body relative to gravity, was modulated using the York Tumbling Room, a fully furnished cubic room with strong directional cues that can be rotated around a participant's roll axis. Sixteen participants were seated upright (relative to gravity) in the Tumbling Room and made judgments about body and hand stimuli that were presented in the frontal plane at orientations of 08, 908, 1808 (upside down), or 2708 relative to them. Body stimuli have an intrinsic visual polarity relative to the environment whereas hands do not. Simultaneously the room was oriented 08, 908, 1808 (upside down), or 2708 relative to gravity resulting in sixteen combinations of orientations. Body stimuli were more accurately identified when room and body stimuli were aligned. However, such congruency did not facilitate identifying hand stimuli. We conclude that static allocentric visual cues can affect embodiment and hence performance in an egocentric mental transformation task. Reaction times to identify either hands or bodies showed no dependence on room orientation.