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Have a question about the brain? Send it to us. Each month, a question is selected and a scientist with relevant expertise responds, with answers posted here.

Past Questions and Answers

What causes déjà vu?

Source: Society for Neuroscience
While it’s difficult to study déjà vu directly in a laboratory, scientists can test how the brain responds to familiar faces and places.

Does practice make perfect?

Source: Society for Neuroscience
While experts debate the type and length of practice that is optimal for success, one thing is clear: training improves performance and changes the brain.

Why are some people left-handed?

Source: Society for Neuroscience
There are likely advantages to having both left- and right-handed individuals in a population.

Do people with depression experience worse symptoms at certain times of the day?

Source: Society for Neuroscience
People with depression often report dramatic changes in mood over the course of the day.

What are hallucinations?

Source: Society for Neuroscience
Hallucinations emerge when inner thoughts and expectations overpower sensory experience.

How does marijuana affect brain function?

Source: Society for Neuroscience
The main active ingredient in marijuana alters the normal communication between cells and circuits in the brain.

SfN welcomes all your brain-related questions.

Every month, we choose one reader question and get an answer from a top neuroscientist. Always been curious about something?