Hunger is a stronger motivational force than thirst, fear or anxiety

Monday, October 17, 2016 by: Daniel Barker
Tags: hunger, motivational behavior, scientific findings

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(NaturalNews) A new study published in the journal Neuron provides a fascinating glimpse into the forces that drive human behavior. The researchers found that hunger is a stronger motivational force than others, including "thirst, anxiety-related behavior, innate fear, and social interactions."

Both humans and animals operate under what has been termed the "hierarchy of needs." In other words, our behavior is based on motivational factors that compete with one another, and in general terms, one motivational driver will dominate depending on the surrounding circumstances.

Motivational forces originate from deep within the brain

In 1906, physiologist Sir Charles Sherrington published the results of his groundbreaking research into animal behavior and its basis in neurological principles. His work introduced the "singleness of action" principle, which established the basis of modern behavioral theory.

In short, this principle means that competing motivational behaviors originate in the central nervous system.

From the introduction of the study:

"Hunger provides one of the strongest homeostatic motivations for behavior in the animal kingdom. Despite the wide diversity of stimuli and competing demands that naturally impinge upon animals, they must select and pursue food in times of caloric insufficiency. To address this homeostatic imbalance, animals must often navigate their environment in ways that require switching between exploratory, defensive, and competing behaviors, indicating tremendous plasticity in feeding behavior."

In layman's terms, this simply means that one motivational factor dominates the actions of animals (and humans), and although shifting from one dominant factor to another is necessary to survival, hunger is the most powerful of these various behavioral instincts.

Previous research into the neurological mechanisms that drive behavior tended to focus on only one motivational factor at a time. In this study, however, the research team set out to explore how the competing behavioral motivations interacted with each other, using mice as test subjects.

Using light to stimulate neurons

To accomplish this, the researchers relied partly on technology capable of stimulating various regions of the brain:

"For the study, the team used optogenetics - a technique that uses light to control cells - to govern nerve cells in the brain known as agouti-related peptide (AgRP) neurons.

"AgRP neurons are situated in the brain's hypothalamus. They are known to regulate appetite and are crucial for survival."

In one of the experiments, the team either withheld food or used the optogenetic techniques to activate the neurons that made the mice feel hunger. These mice were also deprived of water to make them thirsty. A control group was given food but no water.

The team observed that the mice deprived of both food and water opted for food when given a choice between the two. The control group chose water, indicating that hunger is a more powerful motivational factor than thirst.

In another experiment, the team activated the hunger-causing neurons before exposing them to a space containing the scent of foxes – creating an environment that triggered fear and anxiety. The hungry mice overcame their fear to obtain food, while the control group stayed in the "safe" zone.

This suggested that hunger overrides fear as a motivational factor.

Yet another experiment involved giving socially-isolated mice the choice between a chamber containing other mice and one containing food. The hungry mice chose food over companionship, while the non-hungry control made the opposite choice. This experiment indicated that hunger also trumps the need for social interaction.

Interestingly, the neurons associated with hunger became more active when other mice were nearby, suggesting that these neurons are capable of reacting to potential competition for a meal.

Findings shed light on evolutionary development, may also lead to treatments for obesity

The overall findings of these experiments indicated that competing motivational forces "are more deeply connected than previously thought."

The experiments have shed more light on how animals and humans evolved, and how selecting the appropriate motivational factors may have led to the survival of certain species over others.

Further research in this direction may eventually lead to possible treatments for obesity, the researchers said.

Sources:

MedicalNewsToday.com

Cell.com

Brain.OxfordJournals.org