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Is it possible to read dreams with a brain scan?
Humans have been attempting to decipher dreams for thousands of years, trying to answer the big questions - why do we dream and do our dreams reveal anything about our subconscious? Collecting information about dreams is challenging because they are notoriously difficult to remember. Some scientists claim that they can decode dreams using modern technology, potentially bringing us closer to understanding the function and significance of dreams. In order to find out if we really can read dreams using brain scans we asked 4 experts in neuroimaging, neuroscience and sleep research, ‘Is it possible to read dreams with a brain scan?’, here is what they said…
Is it possible to read dreams with a brain scan?
Can we read dreams by scanning the brain?
3 out of 4 of the experts answered ‘no’. Professor Markus Barth, a neuroimaging expert from Queensland University in Australia, says “you can scan a person’s brain while dreaming and map the activity pattern using a method called fMRI or (with lower spatial, but higher temporal resolution) EEG. But it is currently not possible (and will not for quite a while) to know what a person is dreaming as in e.g. read their dreams.”
What can brain scans tell us?
Professor Barth says “First steps in developing brain reading (aka decoding of brain signals) are being taken, but are currently limited to read very basic static shapes (e.g. letters, see our reference below).”
Dr Rebecca Dewey, a neuroimaging and neuroscience expert from Nottingham University in England, says “There are methods of imaging brain function (fMRI, EEG) that allow us to see which areas of the brain are more active than others, or become more active over time.”. She explains that “However, there isn't a one-to-one correspondence for many brain regions. For example, you can tell if someone is experiencing intense visual stimulation because their visual processing areas will be active. With good spatial information (like in fMRI) you might be able to see if someone is processing faces (there is a known area for facial processing) or tracking the movement of an object like a bird or a football (there is a brain area associated with the processing of visual motion) but beyond that level, you don't get a lot of fine-grained information.”
Dr Dewey concludes, “You might be able, using electrophysiological measures like EEG or MEG, to tell THAT someone is dreaming, because the amount of brain activity in certain frequency bands increases or decreases. What that means is the rate at which nerves send their electrochemical messages can change. So we can tell if someone is alert, or calm, or sleepy, or in deep sleep. We might be able to use that to tell us if someone is dreaming - but we're a long way off knowing what they're dreaming *about*.”
Why can’t we read dreams?
If brain scanning technologies like fMRI and EEG can provide so much information, why can’t we use them to read dreams?
Dr Raphael Vallat, an expert in sleep research and neuroscience from California University in the USA, says “One of the fundamental obstacle to this is that there is no way to know for sure whether someone asleep is dreaming or not just by looking at his/her brain activity (measured using EEG or fMRI). Instead, researchers must wake up the sleeper and ask if he/she was dreaming or not before being awakened (and even there one may argue that there is no evidence that the dream actually took place in the seconds/minutes just before awakening). In simpler words, there are no real-time brain activity markers of dreaming that one could use to read dreams.”
Dr Vallat highlights another complication, saying “A second obstacle is that dreams are (most of the time) multi-sensory experiences involving a complex temporal narrative, social interactions, past memories, and emotions. Even though some researchers have attempted to decode the visual content of sleep-onset dreams using template-matching machine-learning models, I highly doubt that we'll be able to fully decode dreams in all their richness and complexity anytime soon.”
We cannot currently decode dreams using brain scans.
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