Neural Correlates of First-Person Perspective as One Constituent of Human Self-Consciousness

Abstract

Taking the first-person perspective (1PP) centered upon one's own body as opposed to the third-person perspective (3PP), which enables us to take the viewpoint of someone else, is constitutive for human self-consciousness. At the underlying representational or cognitive level, these operations are processed in an egocentric reference frame, where locations are represented centered around another person's (3PP) or one's own perspective (1PP). To study 3PP and 1PP, both operating in egocentric frames, a virtual scene with an avatar and red balls in a room was presented from different camera viewpoints to normal volunteers (n = 11) in a functional magnetic resonance imaging experiment. The task for the subjects was to count the objects as seen either from the avatar's perspective (3PP) or one's own perspective (1PP). The scene was presented either from a ground view (GV ) or an aerial view (AV ) to investigate the effect of view on perspective taking. The factors perspective (3PP vs. 1PP) and view (GV vs. AV ) were arranged in a two-factorial way. Reaction times were increased and percent correctness scores were decreased in 3PP as opposed to 1PP. To detect the neural mechanisms associated with perspective taking, functional magnetic resonance imaging was employed. Data were analyzed using SPM'99 in each subject and non-parametric statistics on the group level. Activations common to 3PP and 1PP (relative to baseline) were observed in a network of occipital, parietal, and prefrontal areas. Deactivations common to 3PP and 1PP (relative to baseline) were observed predominantly in mesial (i.e., parasagittal) cortical and lateral superior temporal areas bilaterally. Differential increases of neural activity were found in mesial superior parietal and right premotor cortex during 3PP (relative to 1PP), whereas differential increases during 1PP (relative to 3PP) were found in mesial prefrontal cortex, posterior cingulate cortex, and superior temporal cortex bilaterally. The data suggest that in addition to joint neural mechanisms, for example, due to visuospatial processing and decision making, 3PP and 1PP rely on differential neural processes. Mesial cortical areas are involved in decisional processes when the spatial task is solved from one's own viewpoint, whereas egocentric operations from another person's perspective differentially draw upon cortical areas known to be involved in spatial cognition.

Imagined own-body transformations during passive self-motion

“…Whereas previous studies have highlighted the role of integrating motor signals and proprioceptive information (Amorim et al, 2006;Creem-Regehr, Neil, & Yeh, 2007;Keehner, Guerin, Miller, Turk, & Hegarty, 2006;Kessler & Thomson, 2010;Parsons, 1987;Vogeley et al, 2004;Wraga, 2003;Zacks & Michelon, 2005), this study underlines the central importance of vestibular information for embodied perspective taking. These signals may be of particular importance for mental imagery with respect to one's entire body as opposed to imagery for body parts (Parsons, 1987) where motor and proprioceptive mechanisms may predominate.…”

“…This finding suggests that spatial perspective taking involves the embodied transformation of one's body to adopt the imposed perspective. This 'embodied transformation account' is further supported by neuroimaging studies showing the involvement of motorrelated areas during perspective taking and indicating that spatial perspective taking involves comparable neural mechanisms that are involved in actual bodily movements as well (Vogeley et al, 2004;Wraga, Shephard, Church, Inati, & Kosslyn, 2005;Zacks & Michelon, 2005).…”

Where is my key? Where is his key? Perspective taking and social sensitivity of the Key Search task

“…It may be that FH's poorer performance on the 3rd person perspective version of the task is due to a deficit in Theory of Mind (ToM) which literally involves 'putting oneself in another person shoes' while searching for the key. Our results support the fMRI literature showing that performance on first versus third person perspective tasks depends on different neural processes (e.g., Vogeley, Ritzl, Falkai, Zilles & Fink, 2004). Of course, we cannot completely rule out the possibility of neglect without a more extensive neuropsychological assessment being carried out.…”

The timing of temporoparietal and frontal activations during mental own body transformations from different visuospatial perspectives

“…Other neuroimaging studies focused on the manipulation of the perspective during mental imagery and revealed activations within a network of brain areas including precuneus, prefrontal cortex, somatosensory cortex [Ruby and Decety, 2001], as well as right premotor cortex, superior temporal cortex, and cingulate cortex [David et al, 2006;Vogeley et al, 2004]. It is likely that subjects imagined changes in perspective and position jointly during most aforementioned studies, independently of whether investigators focused on body transformations or perspective changes.…”