Taking a different look at the brain
A chemical produced during sex and linked to addiction has been visualised in a scanner as it washes across rats鈥� brains. The feat means that functional magnetic resonance imaging (fMRI), a workhorse of neuroscience, can now be used to observe the flow of brain chemicals, not just oxygen-rich blood.
By pinpointing increases in blood oxygenation in the brain in response to different events 鈥� a sign that specific groups of neurons are active 鈥� fMRI is responsible for some of the hottest findings about the brain. Now at the Massachusetts Institute of Technology and colleagues have extended its power.
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His team repeatedly mutated a magnetic, iron-containing enzyme that 鈥渓ights up鈥� in fMRI readings. With each mutation, the researchers tested its tendency to bind to dopamine, a learning and reward chemical in the brain involved in sex and addictive behaviours. Mutations that increased this tendency were combined, resulting in a molecule that was both magnetic and strongly attracted to dopamine.
The team injected the molecule into the brains of rats, in a region laden with dopamine-producing cells. When given a chemical that triggers dopamine release, that area 鈥渓it up鈥� under fMRI.
Animal minds
Because the molecule must be injected into the brain, this kind of chemical-based fMRI won鈥檛 be applied to humans anytime soon, says Jasanoff, but it could be used to probe addiction and disease using animals.
His lab is now using the enzyme to view how dopamine-sensitive neurons across animal brains react when the chemical is produced in a specific region. The technique could also be used to probe dopamine鈥檚 role in diseases such as 贬耻苍迟颈苍驳迟辞苍鈥檚.
The magnetic enzyme can in theory be 鈥渆volved鈥� to bind to other brain chemicals.
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