An fMRI study of imagined self-rotation

Abstract

In the present study, functional magnetic resonance imaging was used to examine the neural mechanisms involved in the imagined spatial transformation of one's body. The task required subjects to update the position of one of four external objects from memory after they had performed an imagined self-rotation to a new position. Activation in the rotation condition was compared with that in a control condition in which subjects located the positions of objects without imagining a change in selfposition. The results indicated similar networks of activation to other egocentric transformation tasks involving decisions about body parts. The most significant area of activation was in the left posterior parietal cortex. Other regions of activation common among several of the subjects were secondary visual, premotor, and frontal lobe regions. These results are discussed relative to motor and visual imagery processes as well as to the distinctions between the present task and other imagined egocentric transformation tasks.

Mental Imagery for Full and Upper Human Bodies: Common Right Hemisphere Activations and Distinct Extrastriate Activations

“…Whereas some earlier studies showed that mental imagery of body parts (such as arms and hands) predominantly activates left parietal cortex (Bonda et al 1995;Kosslyn et al 1998;Zacks et al 1999;Creem et al 2001;de Jong et al 2001) we found bilateral or bilateral and right predominant parietal activations for both types of body stimuli that were used in the present study. We suggest that mental imagery of symmetrical body stimuli (such as full or upper bodies used here) activate parietal cortex bilaterally whereas mental imagery of asymmetrical or lateralized body parts more strongly relies on left parietal cortex.…”

“…Both OBTtasks led to strong bilateral activation of parietal cortex. This is concordant with activations at this site observed in most studies investigating the neural correlates of mental imagery of bodily stimuli (Bonda et al 1995;Kosslyn et al 1998;Zacks et al 1999;Creem et al 2001;de Jong et al 2001;Lenggenhager et al 2006), but also non-corporeal objects (Pegna et al 1997;Harris and Miniussi 2003;Vingerhoets et al 2001;Alivisatos and Petrides 1997;Carpenter et al 1999;Kawamichi et al 2007).…”

“…Behavioural, neuropsychological, and neuroimaging studies suggest that processing human bodily stimuli involves brain regions that are at least partially different from those sub-serving the processing of noncorporeal objects (Ionta et al 2010;Wraga et al 2005;Creem et al 2001;Bonda et al 1995;Parsons 1987a, b). With respect to neural mechanisms, neuropsychological findings suggest that the left hemisphere might be dominant for the processing of body parts (Schwoebel and Coslett 2005;Guariglia et al 2002;Sirigu et al 1991;Ogden 1985), although own body illusions and deficits in corporeal awareness have been linked primarily to the right hemisphere Berlucchi and Aglioti 1997).…”

Influence of galvanic vestibular stimulation on egocentric and object-based mental transformations

“…The histograms show the mean response time in milliseconds ( §standard error to the mean, vertical bars) for the plant presented at 60° and 120°( averaged over clockwise and counterclockwise stimuli) for subjects using (a) an object-based versus (b) an egocentric mental transformation strategy These authors found that right anodal GVS involved a bilateral hemispheric activation of the superior temporal gyrus, posterior insula, anterior inferior parietal cortex, as well as right lateral occipito-parietal activation, whereas activations during left anodal GVS were conWned to the right hemisphere only (superior temporal gyrus, posterior insula, anterior inferior parietal cortex). As mental transformation has been shown to rely on bilateral parietal and temporooccipital activations (bodies: Zacks et al 1999;Creem et al 2001;Blanke et al 2005, objects: Kosslyn et al 1998Vingerhoets et al 2001), we speculate that bilateral activations due to right GVS interfere more strongly with bilateral activations during mental transformation in superior temporal gyrus, posterior insula, and inferior parietal cortex. Interference of right GVS at these sites might thus lead to the observed decrease in task performance.…”

“…The exact anatomical location of these mental transformation processes is still controversial and seems to depend on additional variables such as sex, handedness, task diYculty and the control task (Kosslyn et al 1998;Jordan et al 2002). Nevertheless, as described in a meta-analysis by Zacks and Michelon (2005), object-based transformation would rely predominantly on unilateral right fronto-parietal cortex, while egocentric transformation would involve a more bilateral network (temporo-parieto-occipital junction; superior parietal lobule) with either right or left hemispheric predominance (Vallar et al 1999;Zacks et al 1999;Creem et al 2001;Vogeley and Fink 2003;Blanke et al 2005). Thus, the more bilateral cortical network activated by right GVS (see below) may interfere more strongly with mental transformation employing egocentric transformation.…”