How brain turns motivation into goal-oriented action?
Study helps to determine treatments and possible solutions for mental health
(Web Desk) - The study by researchers highlights how brain assist in goal-directed behaviour regulations.
The study found out that the goal-oriented actions are performed by paraventricular nucleus, a particular group of neurons in the brain’s thalamus.
The scientists at the University of Alabama at Birmingham and the National Institute of Mental Health (NIMH) have described the phenomenon in a published paper in Current Biology.
Researchers performed an experiment on mice to determine the motivation translation into action. Mice underwent training in a spacious enclosure featuring a trigger zone at one end and a reward zone over 4 feet away, simulating a foraging-like task.
They learned to wait in the trigger zone until signalled by a beep, then autonomously travelled to the reward zone to receive a small amount of strawberry-flavoured Ensure, before returning to the trigger zone.
Within the paraventricular nucleus, two neuron groups were identified based on the presence or absence of the dopamine D2 receptor, labelled as PVTD2(+) and PVTD2(-) respectively. Dopamine plays a crucial role in facilitating communication between neurons.
Sofia Beas, Ph.D., assistant professor in the UAB Department of Neurobiology and a co-corresponding author of the study, said, “We discovered that PVTD2(+) and PVTD2(–) neurons encode the execution and termination of goal-oriented actions, respectively.
Furthermore, activity in the PVTD2(+) neuronal population mirrored motivation parameters such as vigor and satiety.”
As the trial approached its conclusion, the activity of PVTD2(+) neurons decreased compared to their heightened activity during the anticipation of reward.
In contrast, PVTD2(-) neurons showed increased activity after the trial ended but decreased activity during reward anticipation.
This discovery by Beas challenges the conventional understanding that all PVT neurons are uniform in function. Despite both releasing the neurotransmitter glutamate, PVTD2(+) and PVTD2(-) neurons have distinct roles, providing clarity to previously conflicting data on PVT function.
Traditionally seen as mere relay stations, such as the PVT, researchers led by Beas have uncovered its role in information processing.
The PVT transforms motivational impulses from the hypothalamus into needs and transmits them to the nucleus accumbens (NAc) via axon projections like PVTD2(+) and PVTD2(-) axons.
By connecting PVT axon terminals to NAc neurons with an optical fiber, researchers observed closely aligned activity patterns between the PVT-NAc connection and PVT neuron activity.
Beas highlighted the significance of PVTD2(+) and PVTD2(-) neuron terminals in delivering motivation-related signals to the NAc, crucial for encoding goal-oriented behaviors.
Through extensive data recording and analysis using Functional Linear Mixed Modeling, researchers identified correlations such as increased PVTD2(+) neuron activity during faster trial times.
This understanding of the neural mechanisms behind motivation offers insights into addressing conditions like substance abuse and depression.
It sheds light on how the brain translates motivation into purposeful actions, potentially leading to improved treatments for motivational disorders, thus enhancing mental health.
