טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentKhateb Mohamed
SubjectInformation Processing in the Cortical
Sensory-Motor Loop
DepartmentDepartment of Medicine
Supervisors Professor Jackie Schiller
Professor Yitzhak Schiller
Full Thesis textFull thesis text - English Version


Abstract

The sensory-motor loop of the cortex has become a popular and attractive field in neuroscience in the last two decades. A lot of research has been performed in order to understand how this loop works and what is the function of each of the components of it and how each of them affects the others during active and passive sensation, especially at the cortical level. In other words, understanding the sensory-motor loop is necessary for proper understanding of normal sensation.

In my phd, I investigated more than one important aspect of this loop. First, we investigate the mysterious and poorly-understood area, SII, and tried to better understand its function. We found that it is crucial for texture discrimination by being a higher station for texture coding than SI. Moreover, we proved functional clustering and columns within SII.

Second, we investigate how the connections within the cortical sensory-motor loop affects the sensory responses and coding in the SI barrel cortex. This was performed by optogenetically activating the VM1 while presenting an external somatosensory stimulus to the contralateral whiskers. The activation of VM1 enhances the SI responses in a supralinear manner. In addition, we investigated the kinetical profile of this phenomenon by stimulating VM1 at different time windows in relation to the onset of the peripheral stimulation. Stimulating at about 20 ms before the onset of the peripheral stimulus yields the maximal SI responses. This supra-linearity possibly implies on the involvement of regenerative active mechanism in dendrites. At the functional level, we proved that VM1 activation caused enhancing of the sensory coding reflected in sharpening the SI angular tuning.

Third, we investigated the interesting issue of synchronization in the cortical somatosensory networks during stimulus evoked activity. We found that the networks undergo desynchronization during evoked activity in comparison with spontaneous activity. Moreover, we proposed a specific mechanism to explain this finding- decaying to Rich-club structure of 'small-world-networks' according to two parameters mainly- distance and functionality (neuron's preference).