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The structure of the brain

To understand epileptic seizures, it’s useful to know a little about the structure of the brain.

Lobes of the brain

The largest part of the brain is called the cerebrum, and this is divided into two halves, called hemispheres. Epileptic seizures can start in one hemisphere, or affect both hemispheres from the start. Where a seizure starts is known as the seizure onset.

Focal onset

Focal seizures (also called focal onset seizures) start in one hemisphere of the brain. Sometimes, a focal seizure can start in one hemisphere and then spread to involve both hemispheres of the brain.

Generalised onset

Generalised seizures (also called generalised onset seizures) affect both hemispheres of the brain from the start.

The lobes of the brain

Each hemisphere of the brain has four parts, called lobes, and each lobe is responsible for different functions.

Frontal lobes

  • Personality, behaviour and emotions
  • Judgement, planning and problem solving
  • Body movement
  • Intelligence, concentration and self-awareness

Parietal lobes

  • Processing language
  • Interpreting the signals from our senses of touch, vision and hearing
  • Understanding space and distance (spatial perception)

Occipital lobes

  • Processing visual information

Temporal lobes

  • Understanding language
  • Memory
  • Hearing

Find out more about focal seizures in different lobes.

See this information with references

If you would like to see this information with references, visit the Advice and Information references section of our website. If you are unable to access the internet, please contact our Epilepsy Action Helpline freephone on 0808 800 5050.


Epilepsy Action would like to thank Dr John Paul Leach, consultant neurologist at the Queen Elizabeth University Hospital, Glasgow, for this contribution to this information.

Dr Leach has declared no conflict of interest.

This information has been produced under the terms of Epilepsy Action's information quality standards.

  • Updated July 2019
    To be reviewed July 2022

Comments: read the 3 comments or add yours


My diagnosis just says

"Unprovoked generalised seizure"

So I'm none the wiser

Submitted by michael wevill

I'm 58, have had seizures my whole life. I've had many Neurologist's. The one I'm now seeing, only bout a year or so AND all the info on this page have given me quite the insight.
Thank YOU very much!

Submitted by Paul Young

I have been so shocked to read about Othahara Syndrome I have never heard of it until i came across a video . My Son is 27 years old and is undiagnosed. All the symptoms of this syndrome he has had since birth . He started fitting at 9 days old. We where told that his EEG's were all over the place ( like a childs drawing). I am wondering whether This is what my Son could have

Submitted by Lynne

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