Imaging tactile imagery: changes in brain connectivity support perceptual grounding of mental images in primary sensory cortices.
Constructing mental representations in the absence of sensory stimulation is a fundamental ability of the human mind and has been investigated in numerous brain imaging studies. However, it is still unclear how brain areas facilitating mental construction processes interact with brain regions related to specific sensory representations. In this fMRI study subjects formed mental representations of tactile stimuli either from memory (imagery) or from presentation of actual corresponding vibrotactile patterned stimuli. First our analysis addressed the question of whether tactile imagery recruits primary somatosensory cortex (SI), because the activation of early perceptual areas is classically interpreted as perceptual grounding of the mental image. We also tested whether a network, referred to as 'core construction system', is involved in the generation of mental representations in the somatosensory domain. In fact, we observed imagery-induced activation of SI. We further found support for the notion of a modality independent construction network with the retrosplenial cortices and the precuneus as core components, which were supplemented with the left inferior frontal gyrus (IFG). Finally, psychophysiological interaction (PPI) analyses revealed robust imagery-modulated changes in the connectivity of these construction related areas, which suggests that they orchestrate the assembly of an abstract mental representation. Interestingly, we found increased coupling between prefrontal cortex (left IFG) and SI during mental imagery, indicating the augmentation of an abstract mental representation by reactivating perceptually grounded sensory details.
Neurocomputation and Neuroimaging Unit (NNU), Department of Education and Psychology, Freie Universität Berlin, 14195 Berlin, Germany; Bernstein Center for Computational Neuroscience, 10115 Berlin, Germany; Max Planck Institute for Human Development, Center for Adaptive Rationality (ARC), 14195 Berlin, Germany. Electronic address: timo.schmidt@bccn-berlin.de.
Timo Torsten
TT
Schmidt
Bernstein Center for Computational Neuroscience, 10115 Berlin, Germany; Max Planck Institute for Human Development, Center for Adaptive Rationality (ARC), 14195 Berlin, Germany.
Dirk
D
Ostwald
Neurocomputation and Neuroimaging Unit (NNU), Department of Education and Psychology, Freie Universität Berlin, 14195 Berlin, Germany; Bernstein Center for Computational Neuroscience, 10115 Berlin, Germany; Max Planck Institute for Human Development, Center for Adaptive Rationality (ARC), 14195 Berlin, Germany.
Felix
F
Blankenburg
D000328:Adult; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D055815:Young Adult
Connectivity; Core construction system; Mental imagery; Perceptual grounding; Psychophysiological interaction (PPI); Vibrotactile; fMRI