From the retina to the brain

The idea

The retina's light-sensitive cells are activated by light and generate electrical signals, which the optic nerves carry to the brain, where they are interpreted so that we perceive objects as they are.

A picture is not enough

An image falls on the retina at the back of the eye. But you also need to understand what the picture shows.

What happens to the image on the retina?

• Cells turn it into signals that the brain interprets
• The retina keeps the picture inside the eye
• The lens turns it into sound

Signals to the brain

Press Next step.

Seeing

Light switches on the cells of the retina. They make electrical signals. The optic nerves carry the signals to the brain, and the brain works out what we are looking at.

The retina's light-sensitive cells are activated by light and generate electrical signals, which the optic nerves carry to the brain, where they are interpreted so that we perceive objects as they are.

Notes

Light-sensitive cells of the retina make electrical signals; the optic nerves carry them to the brain, which interprets them.

Check yourself

What do the light-sensitive cells of the retina do when light falls on them?

What carries the signals from the eye to the brain?

What does the brain do with the signals?

• They get activated and generate electrical signals — correct. Yes!
• They change the size of the pupil. The iris controls the size of the pupil. The light-sensitive cells generate electrical signals.
• They bend the light rays. Most bending happens at the cornea. The light-sensitive cells generate electrical signals when illuminated.
• The ciliary muscles. The ciliary muscles change the curvature of the eye lens. The optic nerves carry the signals to the brain.
• The optic nerves — correct. Yes!
• The iris. The iris controls the size of the pupil. The optic nerves carry the signals to the brain.
• It sends them back to the retina to form the image. The image is formed on the retina by the eye lens. The brain interprets the signals it receives.
• It does nothing, because the retina interprets them. The brain interprets the signals and processes the information.
• It interprets them and processes the information so that we perceive objects as they are — correct. Yes!