Spatio-temporal aspects in the control of the visuomotor system

• Autores: Borja Rodríguez Herreros
• Directores de la Tesis: Hans Supèr (dir. tes.), Joan López Moliner (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2014
• Idioma: inglés
• Tribunal Calificador de la Tesis: Yann Coello (presid.), Josep Marco Pallares (secret.), María Pilar Aivar Rodríguez (voc.)
• Materias:
  • Psicología
    • Psicología experimental
      • Psicología fisiológica
• Enlaces
  • Tesis en acceso abierto en:  TDX  Dipòsit Digital de la UB 
• Resumen

  • The complex voluntary motor behavior of higher primates is often regarded as a consequence of the development of sophisticated and adaptive perceptual and motor systems. Theoretical and behavioral investigations suggest that the control of motor acts involves a sequence of neural operations that select, plan and execute a movement. The visuomotor system integrates visual and proprioceptive signals to exert control on visually-guided actions, which generally allows to efficient localization of the stimuli and generation of the appropriate motor commands. Although the last two decades have witnessed a considerable progress on the understanding of the neural basis of visuomotor control, the shortage of the literature assessing directly this process boost the necessity of developing new spatio-temporal frameworks of how this process might work. The present dissertation is focused on providing strong insights about the neural and behavioral aspects subserving the use of spatio-temporal information through vision and proprioception to accomplish accurate goal-directed actions. This dissertation encloses five different studies to shed some light on these issues, by combining neuroimaging and psychophysical tools. These empirical data are presented in Chapters 3 to 7, in the form of five articles. Two studies (Chapters 3 and 4) addressed object localization in reaching, by investigating the neural and behavioral mechanisms by which the integration of visual motion affects the execution of hand movements. We demonstrate that visual illusory percepts affect the hand trajectory toward a misperceived object, in a form that casts some doubts on the suitability of feedback circuits to sustain early motion-position interaction. Two other independent studies (Chapter 5 and 6) focused on the coding of hand location, by examining how the use of proprioception and the felt position of the arm influenced our temporal and spatial accuracy in interception. We uncover an increase in the weighting of proprioceptive signals when intercepting objects under poor visual conditions. In addition, the study of Chapter 6 reveals that proprioceptive cues of the hand location completely adapted to induced displacements of the visual input of the hand. The last study (Chapter 7) dealt with the online monitoring of a reaching movement. We have indentified a causal structure/function relationship between deficits in online motor control and the induction of inhibitory plastic changes over the medial intraparietal sulcus, suggesting this area as the neural locus in charge of the ability to update a motor command. We have found anatomical differences in white matter parietofrontal pathways responsible for the individual differences in the impairment of the online motor control. Taken together, the research presented here strengthens the idea that our visuomotor system acts as a coordinated system that efficiently encodes relevant spatial and temporal features at different neural levels to ascertain a precise reaching behavior. Moreover, the combination of the sensory inputs that provide this information seems to depend on the reliability of the sensory source. I hope the work presented here will encourage the reader to explore deeper in the many aspects of this part of the brain still unrevealed.