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Identifier 000346818
Title Quantitative mapping of monkey cortical areas during oculomotor bahavior : in vivo functional imaging with the autoradiographic method of [14C]-deoxyglucose
Alternative Title Ποσοτική χαρτογράφηση φλοιϊκών εγκεφαλικών περιοχών πιθήκου που εμπλέκονται στην οφθαλμοκινητική συμπεριφορά:in vibo λειτουργική απεικόνιση με τη χρήση της αυτοραδιογραφικής μεθόδου [14C]-δεοξυγλυκόζης
Author Μπακόλα, Σοφία
Thesis advisor Σαββάκη, Ελένη
Reviewer Μοσχοβάκης, Αντώνης
Δερμών, Κατερίνα
Abstract We applied the quantitative autoradiographic method of [14C]‐deoxyglucose to study the location and extent of intraparietal and superior temporal cortical activation in monkeys performing: i) fixation of a central visual target, ii) visually‐guided saccades, and iii) memory‐guided saccades, of similar amplitude and direction as in the visually‐guided paradigms, in complete darkness. By eliminating visual stimulation in the memory‐guided task, we dissociated the effects related to the sensory component from the effects related to the motor component of saccadic behavior. This is the first study to provide high‐resolution two‐dimensional functional and anatomical maps of metabolic activity of the intraparietal and the superior temporal cortices that allowed for direct comparisons between different experimental conditions. In the intraparietal cortex, visually‐guided saccades induced enhanced metabolic activation in approximately the middle and anterior third of the lateral bank of the IPs. The effect spread in both the ventral and dorsal subdivisions of area LIP (LIPv and LIPd, respectively), as we confirmed with histological examination. Our results demonstrate that the oculomotor‐related area LIP extends further rostrally than traditionally reported to include most of the anterior part of the bank. Besides saccade execution, area LIPd requires visual stimulation for maximal activation. The effect induced by memoryguided saccades was equally robust as that induced in the visual‐guided paradigm, but was confined to the middle third of the lateral bank within LIPv. Active fixation of a visual target induced significant metabolic activation in the border of LIPd/LIPv and extended in the anterior part of the lateral bank within area LIPd, covering approximately one‐third of the neuronal space allocated to visually‐guided saccades. We propose that the lateral intraparietal cortex represents visual and motor space in functionally segregated subregions. A rostral subregion located superficially (close to the crown) within the cytoarchitectonically‐defined area LIPd is mainly dedicated to the visuo‐spatial aspect of oculomotor behavior. A caudal one deeper in the bank (close to the fundus) within the cytoarchitectonically‐defined area LIPv is predominantly associated with the motor component of saccadic activity. In the superior temporal cortex, oculomotor behavior activated a constellation of brain areas, providing evidence for their involvement in saccadic eye movements. All areas that comprise the motion‐complex network traditionally implicated in the analysis of visual motion and in smooth‐pursuit execution i.e., MT/V5, in the lower bank of the STs, MST, in the upper bank of the STs, and FST, in the floor of the STs, were significantly activated during visually‐guided saccades. Areas MT/V5 and MST were also activated during memory‐guided saccades. Interestingly, we observed enhanced metabolic activation in the rest of the regions of the caudal STs, which are not usually implicated in oculomotor/fixational behavior. Both the posterior and the anterior subdivisions of area V4t in the lower bank were activated during the execution of visually‐ and memory‐guided saccades, whereas the intermediate part of polysensory area TPO (TPOi) in the upper bank displayed significant activation in the visually‐guided saccade task. Fixation‐related metabolic increases were observed in the areas with central field representations, i.e. the foveal part of MT (MTf), ventrally, in the anterior part of V4t (V4ta), in FST and in area TEO. Our findings demonstrate that areas MT/V5, MST and V4t receive and/or process extra‐retinal saccaderelated information.
Language English, Greek
Subject Visual Cortex
Visual Perception
Οπτική αντίληψη
Οπτικός φλοιός
Issue date 2007-07-26
Collection   School/Department--School of Medicine--Department of Medicine--Doctoral theses
  Type of Work--Doctoral theses
Notes Διατμηματικό μεταπτυχιακό πρόγραμμα σπουδών: ''Εγκέφαλος και Νούς''
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