Columns and Hypercolumns

1. Columns and Hypercolumns Erin Berrisford, Lisa Fenske, Adam Justin, Sara Duxbury, Joe Tuzinski, & Ryan Mastellar

2. History • Hubel and Wiesel • Used a recording electrode to push farther and farther down into the cortex, finding neurons with similar response properties • Neurons with similar orientation are arranged in vertical columns throughout the cortex

3. What is a column? • A column is a trio of vertical cells • Respond to similar stimuli and characteristics • The cells in each column work together to interpret a stimuli • Take a thick, yellow, slanted line • One cell interprets the yellow, another the thickness, another orientation- all these cells work together to see a yellow line that is thick and slanted • Each column prefers input from the left or right eye • Located in the striate cortex • Each column covers about .5mm

4. Hypercolumns • Contains at least two sets of columns that function as a unit • Each is like a mini computer • Each perceives one small portion of the visual field • Enough columns to cover every possible orientation (0-180 degrees) • Each hypercolumn is about 1mm across • Half of the hypercolumn responds to light falling on the left retina, the other half responds to light falling on the right retina • Each hypercolumn has enough cells to respond to light, orientation, and bar width • Includes a pair of columns called blobs

5. Blobs • Function unclear • CO blob columns are thought to aid in processing color (CO stands for cytochrom oxidase- a staining technique enzyme) • Interblob regions process motion and spatial structure

6. Demonstration • http://www.sinauer.com/wolfe2e/chap3/hypercolumnsF.htm

7. Scan in picture and place here

8. To Sum up • Hypercolumns are used by the striate cortex to analyze size, shape, speed, and direction • Each cell is in charge of a certain characteristic but all work together to create the pictures we interpret from the visual world