Body Picture Physical Effects Of Mental Rotation Task

Mental rotation, as a kind of representation transformation, is a very important issue in the field of spatial cognition. Recently, body representation has become a hot point in studies of mental rotation. Numbers of studies found that when presented with rotated body-parts stimuli, the subjects tend to imagine rotating their own body parts to the target position and then make the judgment. The influence of body postures on the rotated body presentation and their neural mechanism have gained more and more attention.This study aimed to investigate the embodied effects involved in the processing of body parts related pictures.18healthy volunteers (9males and9females, age range22-27) were recruited. By using functional magnetic resonance imaging (fMRI), blood oxygen level dependent (BOLD) signals were collected when subjects viewed rotated body parts drawings like hands or feet under different arm postures.Behavioral results suggested a significant main effect on the compatibility of hand postures and pictures. The RTs under compatible condition were significantly faster than incompatible condition. Besides, The RTs on hands picture were faster than feet pictures. Significant difference on orientation was also found which suggested that the judgments on medially rotated pictures were faster than laterally rotated pictures. A significant interaction was also found between body parts and compatibility.The mental rotation task on body parts materials evoked stronger activation in parietal-frontal cortex. In specific, when the left hand was flexed in clockwise orientation (CW), the compatible hand drawings evoked stronger activation in the left supplementary motor area (SMA), left precentral gyrus and left superior parietal lobule (SPL) compared with incompatible hand drawings. When the right hand was flexed in counter clockwise orientation (CCW), the comparison between compatible and incompatible hand drawings revealed significant activations in left inferior parietal lobule (IPL), right SMA, bilaterally middle frontal gyrus (MFG), left inferior frontal gyrus (IFG) and bilaterally superior frontal gyrus (SFG). Same contrasts conducted on feet pictures suggested that there was no significant activated region between the compatible and incompatible feet drawings, which means that the mental rotation of feet drawings remain unaffected by upper limb posture. The posture influences the body parts related mental rotation in an effector-specific way. A direct comparison between medially and laterally rotated pictures revealed activations in right IPL, left precentral gyrus, bilaterally inferior frontal gyrus and bilaterally superior frontal gyrus. This suggested that when subjects imagined the rotation of their hands or feet, the biomechanical constraints affected embodied cognitive process. This result supports the embodied nature of body related mental rotation by suggesting that the inner process of body parts related mental rotation is affected by body status and the biomechanical constriants also influence the body information related cognitive process.