On Monday, I attended a captivating lecture about how we see the world around us titled “Vision”, part of a series of 8 lectures on “The Brain and its Mysteries”, presented by the exceptionally talented neuroscience student, Ethan Newnham, at U3A Box Hill. Vision is a fundamental way we navigate the world, and it was both enlightening and engaging.
Ethan began by emphasizing that while eyes are often called the windows to the soul, they are also windows to the brain. He guided us through the brain’s visual system, promising that the seemingly disconnected pieces of information would eventually make sense.
Neuroscience encompasses the entire nervous system, including the brain and its nerves. Ethan explained that vision starts with the retina, a complex set of light-sensitive nerves that transmit visual information to the brain. However, vision is not solely about the eyes; it is about how the brain processes this information. He highlighted this by stating, “We don’t see with our eyes; we see with our brain.”
We delved into the occipital lobe, home to the primary visual cortex, which processes information from the retina. Ethan explained that visual data travels along the optic nerve, through the thalamus, and finally to the occipital lobe. He used the example of seeing a beautiful image of Blenheim Palace to illustrate how visual processing works.
One of the most intriguing parts of the lecture was the discussion of the groundbreaking experiments by David H. Hubel and Torsten N. Wiesel at Harvard University. Their 1963 experiment involved recording the activity of neurons in a cat’s visual cortex as it observed a screen. They discovered that specific neurons responded to the orientation of a bar, revealing the concept of ‘feature detectors’. These neurons analyze input from neighboring neurons to identify specific features of the visual environment, all happening unconsciously before we even ‘see’ anything.
Ethan further explained that higher-order visual areas process more complex elements of our visual field, again largely unconsciously. He shared a video reenactment of a patient who couldn’t process movement, illustrating how crucial these neurons are for normal vision.
The lecture concluded with a thought-provoking comparison between our brain and modern technology. While cameras capture the world pixel by pixel, our brains process visual scenes instantaneously, integrating features like faces and words seamlessly. Ethan’s final point drove home the complexity and wonder of our visual system: we see not just with our eyes but with an intricate network of brain processes.
Overall, Ethan Newnham’s lecture was a fascinating exploration of the brain’s visual system, making complex neuroscience accessible and engaging for everyone in the audience.
The presentation slides are available in the course resources.