مکتب خانه ای برای اشتراک گذاری آموخته ها، خوانده ها و شنیده ها در باره ی مغز

۵ مطلب با کلمه‌ی کلیدی «fMRI» ثبت شده است

New insights about the nature of brain representations via pattern similarity analysis

سمینار بین‌المللی پژوهشکده مخابرات نظری و قطب علمی سیستم‌های مخابرات

سخنران:

Dr. Hamed Nili
Postdoctoral Researcher
Oxford University
Department of Experimental Psychology

عنوان سمینار:

New insights about the nature of brain representations via pattern
similarity analysis

دوشنبه 3 مهرماه از ساعت 16:30 تا 18

دانشکده مهندسی برق، دانشگاه صنعتی شریف (برق 4)


Abstract:
Recent advances in techniques for analyzing neuroimaging data has shed light into the nature of brain representations. In this talk, I will review some recent work covering a range of  topics from memory encoding and retrieval to concept formation. I will explain
how the paradigm shift from univariate analysis to multivariate pattern analysis of brain responses allows answering new questions
from brain measurements. Finally, I argue that  many of the questions rely on the concept of pattern distances and that a particular approach to multivariate analysis is most appropriate for data analysis.
About Speaker:
Dr. Nili received his BSc degree in Electrical Engineering at Sharif University  of Technology,  specialized in Control engineering. His undergraduate project
was an attempt to design a hands-free wheelchair control system. There, he used features from surface EMG signals to classify four types of hand motions
based on Artificial neural  networks. He  then  did an MSc on applied digital signal processing in Southampton. This was followed by two years of research
in Professor John Duncan's lab in the  University of Cambridge  MRC Cognition and Brain Sciences Unit.  Being John's Research Associate, he worked on
single-cell data to study target detection in the prefrontal cortex. He then started his PhD in the same division at Cambridge under the supervision of Dr
Nikolaus Kriegeskorte. His PhD mainly consisted of developing methods for multivariate data analysis (e.g. the  RSA toolbox) and also orientation
invariance in the human visual system (using fMRI).  Currently, in his post-doc in the Summerfield lab  at Oxford University, he is  mostly using the methods
that he developed in his  PhD as tools  for studying human learning. His  projects span a range from learning abstract categories to transfer learning (the
mechanisms by which learning a task would benefit our performance on similar tasks). He uses fMRI, EEG and behavioural analysis and modelling to  study
the questions of interest.


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مسابقه کشوری پردازش تصاویر تشدید مغناطیسی کارکردی از سوی آزمایشگاه نقشه برداری مغز

به نقل از سایت ستاد توسعه علوم و فناوری‌های شناختی:

آزمایشگاه ملی نقشه برداری مغز در نظر دارد مسابقه ای با موضوع "پردازش تصاویر تشدید مغناطیسی کارکردی (fMRI) برگزار نماید.

سؤال و داده های مسابقه به زودی بر روی وبسایت آزمایشگاه قرار خواهد گرفت. علاقمندان به صورت انفرادی در این مسابقه شرکت نموده و نتایج حاصل از پردازش تصاویر تشدید مغناطیسی را به آزمایشگاه ارسال خواهند نمود. در مرحلۀ بعد، نتایج توسط داوران برجسته ای ارزیابی می گردد. از میان تمامی شرکت کنندگان، از نفرات برتر برای مرحلۀ دوم مسابقه، که به صورت حضوری در محل آزمایشگاه برگزار خواهد شد، دعوت به عمل می آید. در پایان، به سه نفر برتر با حضور ریاست و معاونین محترم آزمایشگاه، جوایز نفیس به همراه لوح تقدیر اهدا خواهد شد. علاقمندان می بایست در گام اول از طریق وبسایت آزمایشگاه اقدام به ثبت نام نمایند. مهلت ثبت نام حداکثر تا تاریخ 96/5/30 می باشد.

جزئیات بیشتر بزودی از طریق وبسایت آزمایشگاه در اختیار ثبت نام کنندگان قرار خواهد گرفت.

برای مشاهدۀ کامل خبر اینجا کلیک کنید.


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Long-term High-capacity Memories of Object Values in the Primate Brain

به نقل از مرکز تحقیقاتی مهندسی عصبی:


این سمینار چهارشنبه اول دی ماه 95 در تالار کنفرانس IPM نیاوران برگزار می‌شود:

Long-term High-capacity Memories of Object Values in the Primate Brain
Wednesday, DEC 21, 2016 (10:00 - 12:00)
Dr. Ali Ghazizadeh
Graduated from John Hopkins and Berkeley Universities
Post Doctoral Fellow at Laboratory of Sensorimotor Research, National Eye Institute (NIH)



Abstract
During our lifetime we are bombarded by a large number of visual stimuli that need to be memorized and discriminated based on their ecological relevance such as their reward value. The basal ganglia, especially their posterior part, play an important role in such visual discrimination (Hikosaka et al 2014). Beyond this basal ganglia circuitry, the neural mechanism involved in such discrimination is not well-known. We addressed this issue by doing whole brain functional magnetic resonance imaging (fMRI) in two rhesus monkeys. Before the scans, the monkeys repeatedly viewed many computer-generated fractals (n>80) which were consistently associated with a large reward (Good objects) or a small reward (Bad objects) for >10 days. During block design scans (>1 day after training), these objects were passively viewed in the periphery (left or right, 6deg) while the monkey kept central fixation with no contingent reward. Thus the differential coding of objects in passive viewing would represent acquired stable object values rather than immediate reward expectations. Scan results showed widespread object Goodness coding (Good > Bad) along the ventral bank of superior temporal sulcus (STS) particularly in areas V4, TEO, TEa as well as in orbitofrontal cortex (OFC) and lateral prefrontal cortex (LPFC). Weaker effects were also observed in early visual areas (V1-3) and lateral intraparietal area (LIP). Various subcortical areas such as basolateral amygdala, ventral claustrum also showed significant Goodness coding (cluster corrected, alpha<0.01). Concomitant with neuronal discrimination, we found strong behavioral discrimination outside the scanner measured as strong gaze bias toward Good objects during free viewing sessions. To test whether neural and behavioral discrimination is maintained in long-term memory, we retested the same objects after 8-12 months with no visual exposure (memory period). Importantly many of the same visual areas along the ventral bank of STS fully retained their Good object discrimination despite long memory interval. There was significant discrimination in areas such as LPFC but with reduced magnitude. Notably free viewing of objects following the memory period revealed persistent gaze bias toward Good objects despite absence of any encounter for many months. Our results reveal a robust and large capacity neural mechanism for discriminating and orienting toward valuable objects. It is not known how such diverse brain areas acquire and maintain Goodness coding. One possibility is that Goodness coding arises in basal ganglia first which in turn train cortical areas. This hypothesis remains to be tested.


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درسی در مورد fMRI

از 21 نوامبر سال جاری درسی با  عنوان Principles of fMRI 1 در مورد طراحی، یادگیری و آنالیز داده‌های Functional Magnetic Resonance Imaging (fMRI) در سایت Coursera آغاز می‌شود.

همچنین نسخه رایگانی از کتاب Principles of fMRI که راجع به مباحث مربوط به درس می‌باشد، نیز در دسترس گذاشته شده است.



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کارگاه عملی

کارگاه پردازش داده های تصویر برداری عملکردی مغز

محل برگزاری: ساختمان لارک پژوهشگاه دانش‌های بنیادی
زمان: 25 تا 27 مهر 95

The second workshop on fMRI data analysis
Instructors:
Reza Rajimehr: McGovern Institute for Brain Research, MIT
Maryam Vaziri: Department of Psychology, Harvard University
Tutors:
Elahe Yargholi: School of Electronical and Computer Engineering University of Tehran
Neda Afzalian: School of Cognitive Sciences, IPM
This
3-day workshop will be held in the Larak building of IPM. The workshop will cover the theoretical aspects of structural and functional MRI data analysis, and will provide hands-on experience in analyzing sample datasets from real experiments.
The workshop will have the following format:
Day 1: Analysis and visualization of structural data in Free surfer
Day 2:
Analysis and visualization of functional data in FS-FAST
Day 3:
Complimentary analysis of structural and functional data in Matlab
Free surefer/FS-FAST is operated in Linux environment. A brief introduction to Linux/Unix will be given at the beginning of the workshop. A basic knowledge of Matlab is required for day 3 of the workshop.
 
     

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