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Identifier 000348330
Title Αναγνώριση και εκτέλεση κινήσεων σύλληψης τρισδιάστατων αντικειμένων με την άκρα χείρα παρουσία και απουσία οπτικής πληροφορίας. In vivo λειτουργική χαρτογράφηση των εμπλεκόμενων περιοχών του φλοιού εγκεφάλου πιθήκου με τη χρήση της ποσοτικής αυτοραδιογραφικής μεθόδου της 2-[14C] δεοξυγλυκόζης
Alternative Title Observation and execution of grasping of three dimensional objects in presence and in absence of visual information. In vivo functional mapping of the monkey brain cortical areas involved, by the use of the quantitative autoradiographic method of 2[14C]-deoxyglucose
Author Ευαγγελίου, Ασημίνα
Thesis advisor Σαββάκη, Ελένη
Reviewer Μοσχοβάκης, Αντώνης
Δαλέζιος, Γιάννης
Χριστάκος, Κώστας
Τραχανιάς, Παναγιώτης
Αργυρός, Αντώνης
Ράος, Βασίλης
Abstract The aim of the present study was to elucidate the cortical regions that are activated during grasping execution in the presence or absence of visual information, as well as the ones implicated in grasping observation. For this reason, we employed the quantitative autoradiographic method of 2 [14C]-deoxyglucose (2DG). This method uses radioactive deoxyglucose, an analog of glucose, to trace glucose consumption and therefore local functional activity, since glucose is the main source of energy for brain cells. Furthermore, it provides direct quantitative assessment of the brain activity based on glucose consumption, has the highest spatial resolution (20μm) as compared to other imaging methods and allows the identification of the affected cortical areas by means of cytoarchitectonic criteria. The 2DG method was applied in Macaca mulatta monkeys, trained at the following tasks: a) execution of grasping in light (EL), b) execution of grasping in dark (ED), c) observation of grasping performed by the experimenter (O), d) observation of the experimenter’s hand reaching towards the behavioural apparatus with hand/fingers extended (Cm), and e) exposure to experimental conditions similar to the ED task, without grasping execution (Cd). In this study we focused on the cortical areas located in the medial parietal convexity, the anterior bank of the parietooccipital cortex and the posterior part of the medial intraparietal bank namely V6, V6A, 5IPp, PGm/7m, area 31 and retrosplenial cortex (areas 29 and 30). The net activations induced by the EL task, involve areas 5IPp, PGm/7m, RSC and V6 at both hemispheres, and area V6Ad at the hemisphere contralateral to the moving forelimb. The ED task influenced the metabolic activity in areas V6Ad and 60 PGm/7m contralaterally and 5IPp and V6 bilaterally. The O task increased the metabolic activity of areas PGm/7m, 31, RSC and V6 at both hemispheres. Common activations for the EL and the O tasks were observed in RSC and PGm/7m at both hemispheres. Execution of grasping in light or in dark (EL and ED tasks), induced common activations in areas V6Ad and PGm/7m at the contralateral hemispheres and in area 5IPp and part of area V6 at both hemispheres. As far as area V6 is concerned, it could be involved in the visual and somatosensory quidance of grasping movements. In support with this view are its connections with arm-related areas such as MIP and V6A which in turn project to premotor area 6. The contralateral activation of area V6A only in the grasping-execution tasks, demonstrates that V6A is related with the execution of grasping only and not with the observation of the same action. Presumably, the arm-movement related activity observed in the dorsal part of V6A, corresponds to neurons that integrate motorsignals related to arm movements with somatosensory signals evoked by these movements, in the service of online quidance of the reaching-to-grasp behaviour. Area PGm/7m which was found bilaterally activated during the EL and O tasks and contralaterally activated during the ED tasks, may be involved in the combination of visuomanual and oculomotor signals for the composition of motor commands (based on kinesthetic and visual signals) for movement generation. The higher metabolic activity observed in this area for the execution tasks as compared to the observation task, may be an indication for the stronger involvement of this area in execution than in recognition of actions. Area 31, which was activated only during observation and not during execution of grasping, may contribute to memory proccesses and in attribution of an action (i.e. grasping) to another agent and not to the self. Similarly, area V6A which was activated during execution and not during observation of the reaching-to-grasp behaviour, could also be involved in the attribution of grasping to the performer (self) and not to another agent. The RSC which was bilaterally activated during the EL and the O tasks, may process contextual associations during object recognition, encoding the current salience of objects in the immediate (visual) scene for orienting and navigating towards them. Also it may be involved in topographic spatial navigation, for situating oneself within a larger environment, using the immediate scene as a cue. Area 5IPp is an area which is reported for the first time in the literature and only partially corresponds to area PIP. The strong bilateral involvement of area 5IPp in the grasping execution tasks performed either in light or in darkness, suggests that 61 this area could participate in the visual and somatosensory quidance of the reachingto- grasp behaviour. More specifically, it could be implicated in providing object positional information, useful for reaching, and object feature/shape information by cross modal (visual and tactile) matching, useful for grasping. The involvement of area 5IPp only in execution and not in observation tasks, implies a possible role of this area in the attribution of an action to the performer (i.e. the monkey) and not to another agent (i.e. the experimenter).
Physical description 73 σ. : πιν. ; 30 εκ.
Language English, English
Subject Neurophysiology
Sense Organs
Issue date 2008-07-30
Collection   School/Department--School of Medicine--Department of Medicine--Doctoral theses
  Type of Work--Doctoral theses
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