به امید خدا یکشنبه 2ام آبان ماه آقای "عرفان ذابح" دانشجوی
مهندسی برق و فیزیک دانشگاه شریف، که با جناب آقای دکتر لشگری همکاری
پژوهشی دارند، ارائه‌ای با موضوع "Horizontal Organization of Thalamic
Input in Visual Cortex"خواهند داشت. جلسه همانند گذشته ساعت 8:30 الی 10
در کلاس 415 دانشکده ریاضی دانشگاه صنعتی شریف برگزار می‌شود.
- توضیح آقای ذابح راجع به کار تحقیقاتیشون:
Thalamocortical
afferents are thought to play a major role in the organization of
visual cortical maps, however, we still have a poor understanding of how
they are horizontally arranged within the cortex. To address this
question, we measured horizontal changes in ON and OFF cortical
retinotopy within cat visual cortex by using multielectrode arrays. We
then performed computer simulations to estimate the horizontal pattern
of thalamic axons that best reproduced the ON-OFF cortical changes.
After giving random values of receptive field position/size/polarity,
synaptic strength per cortical point and axon-terminal size, thalamic
afferents went through two different stages of pruning. In the first
stage (retinotopic pruning), the synaptic weights and axonal branches
changed to match the ON-OFF cortical retinotopy. In the second stage
(fine pruning), we tested three different approaches: 1) minimize number
of thalamic inputs , 2) minimize size of axon terminals, 3) both. Among
the three approaches, the first method provided the best fits to the
cortical data. It reproduced more closely the ON/OFF receptive field
structures, the physiological correlation between the ratios of ON/OFF
axon number and synaptic strength at each cortical point and the larger
horizontal distances covered by OFF afferents.
