- Larger, finer mapping of central region
- Less precise mapping of peripheral regions

University of Michigan - Ann Arbor

The primary visual cortex (V1) has a highly structured organization, which was largely uncovered by the research of David Hubel and Torsten Wiesel. It represents four main dimensions of visual stimuli:
- Location in the visual field
- Ocular dominance
- Orientation
- Color

Organization of primary visual cortex

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

Area V1 representation of location in visual field

- Cells in these columns respond best to stimuli at certain orientations, or angles.
    - For example: upright, or 0 degrees; horizontal, or 180 degrees; etc.
- All cells in a column respond best to stimuli of the same orientation

Orientation columns in area V1

- Depends on special channels from retina to area V4 of visual cortex
- 4 stages of color perception:
    - Cones in retina respond to different light wavelengths
    - Information is processed by retinal cells: retinal ganglion cells are excited by some light and inhibited by others
    - Ganglion cells send information to the LGN
    - Information goes to area V1, and then to additional cortical areas

Color perception

- Some cells in V1 respond equally signals to from each eye
- Some cells in V1 respond more to signals from a particular eye.
- All cells in a vertical column in V1 have the same ocular dominance
    - Respond best to the same eye
    - These columns are further organized into ocular dominance slabs
        - all cells in a slab respond best to the same eye

Ocular dominance columns in V1

A key discovery by Hubel and Wiesel was the highly organized arrangement of neurons in the visual cortex. They found that cells with similar response properties, such as reacting to the same line orientation, are grouped together into vertical structures known as columns. These columns are further organized into larger processing units called hypercolumns.

Columns and Hypercolumns in the Visual Cortex

Imagine a neuroscientist inserts a microelectrode perpendicularly into the surface of the primary visual cortex. As the electrode is slowly advanced, it records the activity of several neurons that lie in a direct line, one after the other. All of these neurons are found to be responsive to stimuli presented in the exact same small area of the visual field. Which of the following additional properties would this specific group of neurons most likely share?

Learn Before

Related