Summary: Food insecurity has lasting effects on both behavior and brain function in mice. Mice raised with food insecurity were more resilient to uncertain situations.
source: University of California at Berkeley
While food insecurity is a problem for a growing segment of the US population – which has been exacerbated by the coronavirus pandemic – few studies have looked at the effect of holiday or famine on brain development in isolation from other factors that contribute to adversity.
A new study led by neuroscientists at the University of California, Berkeley, simulated the effects of food insecurity in young mice and found lasting changes later in life.
“We show that irregular access to food in late juvenile and early adolescence affects learning, decision-making, and dopamine neurons in adulthood,” said Linda Welbrecht, a professor of psychology at UC Berkeley and a member of the Helen Wells Institute of Neurosciences.
One of the main differences in behavior involved cognitive flexibility: the ability to find new solutions when the world changes.
“Mice seeking rewards may be inflexible, sticking to only one strategy even when it is not returning a reward, or they may be flexible and try new strategies quickly. We have found that the stability of the food supply when they were young governs how resilient they are under different conditions as they have grown up, “She said.
Epidemiological studies have linked food insecurity in children and adolescents to weight gain later in life, as well as learning problems and lower grades in math, reading, and vocabulary. But these studies are muddled by other issues related to poverty, such as maternal depression and environmental stresses.
The new study was designed to look at the developmental and behavioral effects of food insecurity in a controlled environment that is not possible with people.
The study has implications for humans. Policy makers recognize the importance of good nutrition in early childhood through high school, with free, federally funded or discounted breakfast and lunch programs available in schools across the United States.
The Federal Supplemental Nutrition Assistance Program (SNAP) also provides benefits to supplement the food budget for families in need. For families living paycheck to paycheck, these food programs have shown effects—in particular, they boosted performance in school and graduation rates.
But there may be times when kids don’t have access to food programs, like summer vacation. Programs may also inadvertently create a cycle of feast and famine when benefits are spread out weeks between payments, potentially leaving poor families unable to afford food at the end of each payment cycle. According to a recent report from the US Department of Agriculture, 6.2% of families with children – 2.3 million total households – were food insecure in 2021.
“I think we have to understand that even transient food insecurity is important, the brain doesn’t catch on later. Food insecurity can have long-term effects on how someone’s brain works.”
“The ability to learn and make decisions is something that develops during childhood and adolescence, and we see how these critical skills are affected by access to food. Access to food is something we can address in this province.”
“Nutrition and benefits programs exist, and we can improve them by making access to benefits or food more reliable and consistent. Supporting brain development is a good reason to support food programmes.”
The research, conducted with UC Berkeley faculty Helen Batyub, Stephane Lammel and their lab colleagues, will appear in an upcoming print edition of the journal. current biology. It was posted online on July 20.
Flexibility under changing rules
Wilbrecht and her colleagues, including Robert Wood Johnson Foundation health and society researcher Ezequiel Gallars, simulated human food insecurity in mice by delivering food on an irregular schedule while still allowing enough food to maintain a safe body weight.
This diet was started a week before puberty in mice, the equivalent of late childhood in humans, and continued for 20 days through the equivalent of late adolescence in mice. Food was given to another group of mice whenever they wanted it.
Then they tested cognition in adulthood using foraging tasks in which the mice searched in an altered environment for rewards. For example, the behavior—in this case, knowing the scent that led to the Honey Nut Cheerios—may be successful for a short time, but not forever. The second scent now predicted where the reward would be hidden.
Well-fed, food-insecure mice were tested as adults under certain and uncertain conditions, with notable differences in cognitive flexibility. Food-insecure mice were more resilient in uncertain situations than well-fed mice, while well-fed mice were more resilient in more sedentary situations.
“You have to test in the field to see how these different resilience traits affect survival,” she said. “The results are subtle, but hopeful, because we identify both job gain and loss in learning and decision-making that resulted from the experience of scarcity.”
While the effect of food insecurity on cognition in male rats was strong, female rats showed no effect on cognition.
“This is one of the strongest behavioral influences we’ve ever seen when we’re modeling adversity,” Wilbrecht said.
However, food insecurity had other negative effects on female rats. Women who were food insecure growing up tended to gain weight when given unrestricted food in adulthood, something that is mirrored in humans who grew up food insecure. Male rats did not show such an effect.
PhD student Wan Chin Lin and researchers in the labs of Patioub and Lamil also studied the brain’s reward network, which is governed by the neurotransmitter dopamine, and found changes there, too, in male mice.
“We found that neurons in the dopamine system, which is critical for learning, decision-making, and reward-related behaviors, such as addiction, were significantly altered in both their inputs and their outputs,” Wilbrecht said. “It indicates that there are broader changes in the brain’s learning and decision-making systems.”
For example, the researchers observed changes in the synapses of dopamine neurons that project to the nucleus accumbens and also found changes in dopamine release in the dorsal striatum. These dopamine neurons have been shown to play a role in learning and decision-making in many other studies.
Researchers are continuing their studies of food-insecure mice to determine whether they are more susceptible as adults to addictive behaviors, which are linked to the dopamine network.
About this research in Neuroscience News
original search: open access.
“Transient food insecurity during the juvenile and adolescent period affects adult weight, cognitive flexibility, and dopamine neurobiology.By Wan Chen Lin et al. current biology
Transient food insecurity during the juvenile and adolescent period affects adult weight, cognitive flexibility, and dopamine neurobiology.
- In males, evolutionary feeding history influences cognitive flexibility in adulthood
- Nutrition history groups respond differently to negative outcomes and uncertainty
- Feeding history affects synapses in dopamine neurons and dopamine release
- In females, evolutionary feeding history influences adult weight
A major challenge for neuroscience, public health, and developmental biology is to understand the effects of scarcity and uncertainty on brain development. Currently, a large portion of children and adolescents worldwide suffer from unsafe access to food.
The aim of our work was to test in mice whether the transient experience of insecurity versus safe access to food during the juvenile and adolescent period resulted in lasting differences in learning, decision-making, and the dopaminergic system in adulthood.
We manipulated feeding schedules in mice from postnatal day (P) 21 to P40 due to food insecurity or advertising fame They found that when tested in adulthood (after P60), males with different developmental feeding histories showed significant differences on multiple measures of cognitive flexibility in learning and decision-making.
Adult females with different developmental feeding histories showed no differences in cognitive flexibility, but did show significant differences in adult weight. We then applied reinforcement learning models to this behavioral data.
The best-fit models suggested that in males, evolutionary feeding history changed how mice update their behavior after negative outcomes. This effect was sensitive to the context of the task and the contingency reward.
Consistent with these findings, in males, we found that the two feeding history groups showed significant differences in the AMPAR/NMDAR ratio of excitatory synapses on dopaminergic neurons in the midbrain accumbens nucleus and elicited dopamine release in the dorsal striatum targets.
Together, in a rodent model, these data demonstrate that transient differences in feeding history in the juvenile and adolescent period can have significant effects on adult weight, learning, decision-making, and dopaminergic neurobiology.