Year: 2013
Type: dissertation
Abstract: The ability to imagine is regarded as an extraordinary human capacity.Humans are capable of mentally manipulating internal representations.People are for instance able to imagine a beautiful mountain landscape that they have seen during their holiday or imagine how it feels to drive your motorcycle through the tight corners in that same landscape.The visualization of the mountain scene is likely to encompass mainly visual environmental cues, whereas imagining steering your motorcycle is likely to also encompass the imagery of vestibular and movement related information.These two examples suggest that there are different sorts of mental imagery.In general, imagery is understood as a reconstruction of actual perceptual experience from the past (Guillot & Collet, 2010).There is an accompanying type of imagery for every perceptual modality, namely visual imagery, olfactory imagery, auditory imagery, vestibular imagery and kinaesthetic imagery.In addition, there is also motor imagery, combining simulations in multiple modalities.A typical example of motor imagery is imagining walking down a corridor.In a formal definition motor imagery is defined as a dynamic state during which a subject mentally simulates a given action without overt movement (Decety, 1996c;Sharma, Pomeroy, & Baron, 2006).The content of motor imagery is subject to debate as motor imagery often relates to actions that are accompanied with visual experiences of that same action and, consequently, cannot be completely segregated from visual imagery (Jeannerod, 1994).A possible way to solve this conceptual confusion is to distinguish between visual imagery and kinaesthetic imagery (Callow & Hardy, 2004;Jeannerod, 1994), in which the latter refers to the experience of the proprioceptive and tactile sensations accompanying a movement.Visual imagery refers to the process of visualizing a movement of non-corporeal objects or one's own body (parts) without simulating the kinaesthetic aspects of that movement (Guillot & Collet, 2010;Jeannerod, 1995).As an imagined movement is a mixture of both visual and kinaesthetic information, motor imagery can be seen as a combination of kinaesthetic imagery and visual imagery (Callow & Hardy, 2004).For consistency, we will use the term motor imagery as encompassing both the visual and kinaesthetic experience of the movement of one's own body parts from a first person perspective.Furthermore, we will use visual imagery as a more general term for mental visual transformations (i.e., external or internal visual imagery).This thesis focuses on the factors that affect motor imagery engagement.This topic is addressed in four main topics, namely: (1) context dependency (Chapter 2), (3) kinaesthetic influences (Chapters 3, 4), (3) Neural and cognitive mechanisms of motor imageryNeuroimaging studies have shown that motor imagery involves the activation of widely distributed cerebral structures (Annett, 1995) (For a comprehensive review and meta-analyses see Grezes & Decety, 2001;Zacks, 2008.)During both explicit and implicit motor imagery tasks increases in activation have been found in the primary motor cortex (M1), premotor cortex, supplementary motor area and parietal lobe.All areas are known to be involved during action execution (Grezes & Decety, 2001;Lotze et al., 1999;Zacks, 2008).These findings imply a neural overlap between motor imagery and motor planning and execution (de Lange, Roelofs, et al., 2008).The involvement of M1 is however subject to debate.Several studies have reported an (attenuated) activation of M1 in motor imagery (e.g., Dechent, Merboldt, & Frahm, 2004;Lotze et al., 1999).But others did not find M1 involvement during motor imagery (e.g., de Lange et al., 2005;L. M. Parsons et al., 1995;Richter et al., 2000).This discrepancy might be explained by the different types of paradigms used (de Lange, Roelofs, et al., 2008).The parietal lobe has been shown to play a crucial role during motor imagery.It is known to be involved in the multimodal integration of sensory information and efferent copy signals for the construction of spatial representations (Andersen, Snyder, Bradley, & Xing, 1997).These spatial representations can be coordinated in both an allocentric-or egocentric frame of reference (Andersen & Buneo, 2002;Snyder, Grieve, Brotchie, & Andersen, 1998).In allocentric coordinates an object is spatially represented with respect to the environment.Egocentrically mapped objects are represented relative to the body on the basis of kinaesthetic information (e.g., proprioceptive and tactile sensory input), vestibular information and motor signals (Galati, Pelle, Berthoz, & Committeri, 2010).The intraparietal sulcus is involved in the merging of the motor plan with the allocentric and egocentric representation of (non-) corporal objects (Colby & Goldberg, 1999;de Lange et al., 2005;Graziano, Cooke, & Taylor, 2000).Higher activation of the intraparietal sulcus with larger incongruence between the own posture and the desired end posture exemplifies this notion (de Lange et al., 2006).The topic of Chapter 5 is the Chapter 2Mental Rotation Task of Hands: Differential Influence of the number of Rotational Axes
Author: Arjan C. ter Horst
Language: English
Subfield: Developmental and Educational Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
OpenAlex ID: W269637978