Research studies show how the brain helps regulate goal-directed behavior.
The researchers found that brain-directed movements are carried out by the paraventricular nucleus, a specialized group of neurons in the thalamus of the brain.
Scientists from the University of Alabama at Birmingham and the National Institute of Mental Health (NIMH) describe the phenomenon in an article published in the current issue of Biology.
Scientists conduct experiments on mice to determine the translation of motivation into action. Rats were trained in a large field with a trigger zone at one end and a reward zone more than 4 meters away, simulating a grass-eating task.
They are taught to wait until the runway is marked and then travel alone where they get a taste of the Safety strawberry before returning to the runway.
In the paraventricular nucleus, two groups of neurons were identified based on the presence or absence of dopamine D2 receptor expression, PVTD2 (+) and PVTD2 (−). Dopamine plays an important role in facilitating communication between neurons.
“We found that both PVTD2 (+) and PVTD2 (-) neurons encode activation and inhibition of the same target,” said Sofia Beas, associate professor of neurobiology at UAB and co-author. directed action.
In addition, the activity of the PVTD2 (+) neuron population reflected stimulus parameters such as strength and satiety.
After learning was completed, the activity of PVTD2(+) neurons decreased compared to their activity during reward anticipation.
In contrast, PVTD2 (-) neurons showed increased activity after testing but decreased activity during reward anticipation.
This discovery by Beas challenges the conventional wisdom that all PVT neurons work the same way. Although both release the neurotransmitter glutamate, PVTD2 (+) and PVTD2 (-) neurons have different roles, clarifying previously conflicting data on PVT function.
Traditionally considered a relay station like PVT, researchers led by Beas discovered their role in processing information.
The PVT transduces excitatory impulses from the hypothalamus to the nucleus accumbens (NAc) via axons such as PVTD2 (+) and PVTD2 (-) axons.
By connecting PVT axon terminals to NAc neurons using optical fibers, researchers observed a correspondence pattern between the PVT-NAc junction and PVT neuron activity.
Rice demonstrated the importance of PVTD2 (+) and PVTD2 (−) neuron terminals in transmitting motivational signals to the NAc, which is essential for encoding goal-directed behavior.
Through extensive recording and data analysis using functional linear mixed models, researchers identified correlations such as increased activity of PVTD2(+) neurons during rapid testing.
Understanding the neural mechanisms behind motivation provides insight into dealing with conditions such as addiction and depression.
This shows how the brain translates motivation into goal-directed action, which can lead to improvements in motivational disorders and thus improve mental health.
