How does a brain made of cells produce thoughts?

How do brain cells pass information?

Neurons are cells that communicate through electrical and chemical signals. An electrical pulse reaching a cell’s sending end can release chemicals called neurotransmitters. At a chemical synapse, the junction between cells, these chemicals cross a tiny gap and attach to receptors on the receiving cell. Receptors are proteins that respond to particular messengers.

Some messages make the receiving cell more likely to send an electrical signal; others make it less likely. The messenger is then removed or recycled. These interactions let connected cells influence one another.

Why do thoughts pop into your head?

In a 2009 study, Christoff and colleagues scanned participants during a simple task and periodically asked whether their attention had wandered. Off-task reports were associated with activity in several groups of brain regions, including default and executive networks.

This connects people’s reports with measured activity. It does not identify the exact content or cause of every passing thought.

Do we use only 10% of our brains?

No. The 10% claim is a myth. Brain imaging shows several areas working during an activity, depending on the function needed. Different activities draw on different regions. That does not mean every part is equally active during every task, or that every neuron fires at once. There is no unused 90% waiting to be switched on.

For the broader question of what these findings mean for the mind, see is the mind just the brain?.