MRI reveals brain activity during gambling
People make risk-versus-reward decisions every day, whether making purchases or deciding how
to travel to work. Despite the important role of risk in decision-making, neuroscience
studies have focused on perceived reward. Furthermore, researchers have identified
the regions of the cerebral cortex involved in gauging risk versus reward, but data
for subcortical regions are ambiguous. However, Kerstin Preuschoff and colleagues
at the California Institute of Technology in Pasadena wagered that they could determine
the subcortical structures involved in gambling using functional MRI, which employs
radio signals and magnetic fields to measure blood flow in the brain.
In the study, subjects bet $1 that either the
first or second card in a deck of 10 would have a higher value. The reward probability
and risk varied with each bet. The scientists believed that they eliminated confounding
factors, such as varying complexity, learning, motivation and salience.
The scientists analyzed the period
between the revelation of the first and second cards. In the Aug. 3 issue of Neuron,
they reported that activity appeared in several subcortical brain regions that respond
to the neurotransmitter dopamine. Of particular interest, the ventral striatum exhibited
activity that initially corresponded to reward and later correlated with risk. Preuschoff
said that it is the first brain region discovered that encodes both.
The researchers said that their results
could apply to pathological conditions — such as gambling addiction, bipolar
disorder and schizophrenia — that are associated with risky behavior.
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