A new study published in Science Advances has shown how the brain gives credit to events, along with how transcranial ultrasound (TUS) can disrupt this process.
Imagine passing an exam, and thinking your success was down to the socks you wore or the number of biscuits you’d eaten, rather than the hours of study you’d put in.
This is issue of ‘credit assignment’, where a person or animal attributes the wrong outcome to an event, exists in a variety of psychiatric disorders, like addiction or OCD where people still believe that drug consumption on engaging in certain rituals will lead to positive outcomes.
Now a new study in macaque monkeys has shed light on which parts of the brain support credit assignment processes and, for the first time, how low-intensity transcranial ultrasound stimulation (TUS) can modulate both brain activity and behaviors related to these credit assignment processes.
While currently developed in an animal model, this line of research and the use of TUS could one day be applied to clinical research to tackle psychiatric conditions where maladaptive decisions are observed.
Led by the University of Plymouth and published in the journal Science Advances, the study shows that credit assignment-related activity in the lateral prefrontal area of the brain, which supports adaptive behaviors, can be safely and quickly disrupted with TUS.
After stimulating this brain area, the animals in the study became more exploratory in their decisions. As a consequence of the ultrasound neuromodulation, behavior was no longer guided by choice value – meaning that they could not understand that some choices would cause better outcomes – and decision-making was less adaptive in the task.
The study also showed that this process remained intact if another brain region (also part of the prefrontal cortex) was stimulated; showing for the first time how task-related brain modulation is specific to stimulation of areas that mediate a certain cognitive process.
The work was co-led by the Wellcome Centre for Integrative Neuroimaging at the DOI: 10.1126/sciadv.abg7700