Group A3 Presenters: Anastasia Christopher, Carol Rego, Sarah McNeil Technical Experts: Bonnie Chan, Herman Gill, Marisa Leung

 Brief overview of Module 3  Background information and important definitions  Anatomy of the brain  Lateral Geniculate Nucleus ◦ Method ◦ Results  Primary Visual Cortex ◦ Method ◦ Results  Conclusion Anastasia Christopher

By: Charles Gilbert and Torsten Wiesel Anastasia Christopher

 Receptive Field Size  Cortical Topography  Binocular Retinal Lesion  Scotoma Anastasia Christopher

Is the locus of change in regards to sensory input located at the cortical level (Primary Visual Cortex) or at a prior stage in the sensory pathway (Lateral Geniculate Nucleus)? Anastasia Christopher

Immediately After Lesion2 Months After Lesion LGN Primary Visual Cortex Anastasia Christopher

 Studied 2 cats and 1 monkey  Topographical mapping of the LGN  Multiple electrode penetrations across the LGN  Two injections of retrograde tracers in V1 Carol Rego

 Large silent area about 1mm in diameter  Shift in RF position Carol Rego

Immediately After Lesion2 Months After Lesion LGN ________________ Large silent area Shift in RF position No evidence in plasticity observed Primary Visual Cortex ________________ Carol Rego

 Studied 4 cats and 6 monkeys  RF maps were made using vertical electrode penetration  RF maps were made at the same sites before, immediately after, and 2 months after making the lesion Sarah McNeil

 Immediately after: ◦ Inactivity in original sites ◦ 5X larger sites ◦ Centrifugal shift Sarah McNeil Before lesion Immediately after lesion

 2 months after: ◦ RF field size shrunk ◦ 5˚ centrifugal shift in position ◦ Area of activity expanded beyond affected area Sarah McNeil Before Lesion 2 Months After Lesion

 Initial shock  Long term consolidation Sarah McNeil

Immediately After Lesion2 Months After Lesion LGN ________________ Large silent area Shift in RF position No evidence in plasticity observed Primary Visual Cortex 5X larger in RF sites Centrifugal shift >1 ˚ RF field size shrunk to several times the original size Area of activity expanded Centrifugal shift 5 ˚ Sarah McNeil

Anastasia Christopher Is the locus of change in regards to sensory input located at the cortical level (Primary Visual Cortex) or at a prior stage in the sensory pathway (Lateral Geniculate Nucleus)?

 Brain is high in plasticity  Compensation of damaged tissue as a result of binocular retinal lesions does not take place in LGN  Takes place at the cortical level of V1 Anastasia Christopher