Brain Function and Hemispheric Specialization

Early Brain Mapping by Wilder Penfield

In the 1940s, Wilder Penfield, a Canadian neurosurgeon, treated epileptic patients at McGill University’s Montreal Neurological Institute by surgically removing specific brain areas that triggered seizures.

✔ Before surgery, he used electrical stimulation on the motor and sensory cortex to identify which body parts responded to specific brain regions.

✔ Along with Herbert Jasper, he created the homunculus map, illustrating the connection between brain sites and body functions.

The Discovery of Brain Lateralization

During the 1960s, studies at the California Institute of Technology provided deeper insights into brain lateralization (functional specialization of brain hemispheres).

✔ The left and right hemispheres look similar but have distinct functional roles.

✔ The corpus callosum, a thick nerve band, allows the two hemispheres to communicate.

✔ In severe epilepsy cases, parts of the corpus callosum were surgically severed, creating split-brain patients (now a rare procedure).

Roger Sperry’s Split-Brain Experiments

In 1964, Roger Sperry and his student Michael Gazzaniga studied split-brain patients and monkeys, testing each hemisphere independently.

✔ They found that each hemisphere could learn separately but had no awareness of what the other hemisphere had learned.

✔ Their research confirmed that the left and right hemispheres specialize in different functions.

✔ Sperry won the 1981 Nobel Prize for his groundbreaking work on split-brain studies.

Left Brain vs. Right Brain: Myth or Reality?

The concept of left-brained vs. right-brained individuals has become a popular belief:

✔ Left-brain thinkers: Logical, analytical, structured, and fact-oriented.

✔ Right-brain thinkers: Intuitive, creative, emotional, and artistic.

However, scientific evidence does not support these labels. The brain works as an integrated whole, with both hemispheres contributing to various tasks rather than operating independently.

The idea that the left brain governs analytical and structured thinking, while the right brain drives creativity, is widely recognized but has been largely debunked by neuroscientists.