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Transcript of Need a textbook? Email Sheldon
Need a textbook? Email Sheldon
Goals and Methods
What is the goal of Cognitive Neuroscience?
Goals and Methods• Broad goal is to understand how the brain
accomplishes cognitive processes such as attention, memory, language and consciousness
• There are several smaller questions in this:– What structures do what jobs?– How is information represented in these structures?– How is information passed between these structures?
Anatomy
• What is the difference between Structural Anatomy and Functional Anatomy?
• What roles do each play in our understanding of the brain?
Structural Anatomy• Brain structures are identified in a hierarchical fashion
(with substantial randomness)• Hemispheres -> Lobes -> Sulci & Gyri• Sulci and Gyri are all named
– but somewhat variable across individuals
Structural Anatomy• Brodmann Areas defined by cytoarchitecture
– map of variations in cellular morphology– It is probably not coincidence that Broadman areas are
also generally functionally distinct
Connectivity
• Anatomists are also concerned with brain regions and how they are interconnected
• Interconnectedness occurs at various levels:– interneurons– cortico-cortical connections– thalamo-cortical and cortico-thalamic– afferent = “to” (e.g. sensory) and efferent =
“from” (e.g. motor)
Connectivity
• How do anatomists study connectivity?– Retrograde Tracers (e.g. horseradish
peroxidase) follow axons back to where they came from
– Anterograde Tracers (e.g. dextran) follow axons to where they are going
Connectivity
• Diffusion Tensor Imaging (DTI)– MRI Technique that
traces long white matter tracts
Connectivity
• “Ascending” and “descending” projections in sensory systems– estimate: for every
ascending projection there are ten descending projections
Connectivity
• “Ascending” and “descending” projections in sensory systems– estimate: for every ascending projection
there are ten descending projections
Why would we have descending projections?
Connectivity
• It is the inter-connectivity of the brain that (probably) allows it to perform the vastly complex processes of cognition
Structural and Functional Imaging
• There are a number of well known techniques to create images of brain anatomy– CAT scan, MRI, X-Ray,
• Note however that structural and functional images are not the same thing!
Structural and Functional Imaging
• There are a number of well known techniques to create images of brain anatomy– CAT scan, MRI, X-Ray,
• Note however that structural and functional images are not the same thing!
• Which is more useful? If you could go back in time and give one of these techniques to the earliest neuroscientists, which would it be?
Structural and Functional Imaging
• This is a Functional MRI Image !?
Structural and Functional Imaging
• This is a structural MRI image (an “anatomical” image)
Structural and Functional Imaging
• What you really want is both images co-registered
Structural and Functional Imaging
• What you really want is both images co-registered
• Why? What’s wrong with the functional image alone?
Structural and Functional Imaging
• Functional images tend to be lower resolution and fail to convey spatial information
Pixels
Structural and Functional Imaging
• Structural images have finer (smaller) pixels
Pixels