A slide jammed in a projector revealed that neurons in the visual cortex respond to edges at particular angles — and opened up how the brain builds vision piece by piece.
History of Neuroscience
Intermediate
Hubel, Wiesel and the Visual Cortex
The Editors
April 28, 2026
2 min read
In plain English
In the late 1950s David Hubel and Torsten Wiesel recorded from single neurons in cats' visual cortex. They found cells that fire only for lines at a specific angle — the brain's building blocks for seeing shapes. They also showed that early visual experience shapes these circuits.
Intermediate level: Builds on the basics. Introduces the real vocabulary and the mechanisms behind it.
Concepts to know first
In 1958, at Johns Hopkins University, the Canadian David Hubel and the Swede Torsten Wiesel were trying to find out what makes neurons in the primary visual cortex of anaesthetised cats fire. They projected spots of light onto a screen in front of the cat, as other researchers had done successfully for the retina. Nothing much happened.
The lucky edge
Then, as they slid a glass slide into the projector, a neuron began firing furiously. It wasn't the spot on the slide that excited it — it was the faint edge of the glass, sweeping across the screen at a particular angle. Turn the edge a little, and the cell went quiet.
Simple and complex cells
Hubel and Wiesel went on to classify cells in the visual cortex. Simple cells respond to a line or edge at a specific orientation in a specific place. Complex cells respond to an orientation anywhere within a larger area, often to movement in a particular direction. Neighbouring cells share preferences, arranged in columns. Their picture was a hierarchy: simple features combine into more complex ones, step by step. That idea later inspired the design of artificial neural networks for image recognition.
Experience shapes the brain
They also covered one eye of young kittens for a few months. Afterwards, very few cortical cells responded to that eye, and the animal was effectively blind in it — even though the eye itself was fine. The same deprivation in adult cats had little effect. This revealed a critical period in which experience wires the brain, with direct implications for treating childhood conditions such as cataracts and lazy eye. Hubel and Wiesel shared the 1981 Nobel Prize with Roger Sperry.
Everyday examples & things to try
Picture it
Edge detectors
Imagine thousands of tiny inspectors, each holding a stencil of a line at a different angle. As an image arrives, each inspector shouts when its line matches. Together, their shouts outline every edge in the scene. That's roughly what the first stage of the visual cortex does.
Key takeaways
- Neurons in primary visual cortex respond to edges at specific orientations.
- Simple and complex cells suggested vision is built hierarchically.
- Kitten experiments revealed a critical period when experience wires the visual system.
Explore further
Search YouTube for…
Tap a phrase to copy it, then paste it into YouTube's search box. This site doesn't link to other websites — pick channels from universities, hospitals and established science educators.
Tagshistoryvisioncortex
Keep reading
History of Neuroscience
Beginner
Ancient Egypt and the Edwin Smith Papyrus
The oldest known written description of the brain comes from an Egyptian surgical text copied around 1600 BCE — a practical trauma manual that noticed head injuries could paralyse the body.
August 31, 2026 · 2 min read
History of Neuroscience
Beginner
Broca, Wernicke and the Language Areas
A patient who could only say 'tan', and another who spoke fluently but made no sense: how two 19th-century neurologists discovered that language lives largely in the left hemisphere.
May 17, 2026 · 3 min read
History of Neuroscience
Intermediate
Descartes and the Mechanical Reflex
René Descartes pictured the body as a machine of tubes and valves, sketched the first reflex, put the soul in the pineal gland — and left neuroscience the mind-body problem.
February 3, 2026 · 2 min read