A new study from the University of Maryland, Baltimore County (UMBC) reveals how two different parts of the brain’s memory centers work together in a key reward region to help mice (and perhaps humans) combine memory of place and context with motivation to pursue rewards.
The findings provide new insights into how the brain integrates information about where and what feels good to make everyday decisions, such as going to a favorite restaurant to meet a friend or seeking a rewarding experience. Specifically, the findings, published in the Journal of Neuroscience, show that inputs from the dorsal and ventral hippocampi converge on the same individual neurons in separate brain regions, the nucleus accumbens, where they interact and amplify each other’s effects.
The hippocampus-nucleus accumbens connection is where your brain’s map of where to go meets your sense of why it’s worth going. ”
Tara LeGates, senior author, assistant professor in the UMBC School of Biological Sciences
For many years, scientists viewed connections from the dorsal hippocampus, which is more closely tied to spatial memory and navigation, and the ventral hippocampus, which is more tied to emotion and motivation, as largely separate entities. This paper challenges that understanding.
“A single neuron can receive input from different areas of the brain, and understanding how it integrates them is critical to understanding what drives goal-directed behavior,” Legates says.
Although the current research focuses on individual cells, the implications are much broader. A deeper understanding of how these reward-related circuits process and combine information could help us understand conditions in which motivation is inhibited, such as depression, addiction, and anxiety disorders.
Close-up of convergence
Using advanced methods, including using light to stimulate specific pathways (a technique called optogenetics), precise recording of neurons’ electrical activity, and detailed microscopic imaging, the researchers identified groups of neurons in specific parts of the accumbens that receive direct input from both the dorsal and ventral hippocampi.
Importantly, the synapses involved in these two pathways are located very close together, often within a few microns (thousandths of a millimeter), on the same branch of a neuron’s dendrites, which look like the roots of a tree on a neuron. Their proximity allows them to influence each other quickly. The researchers found that when both inputs were activated simultaneously, the combination produced a stronger response than either one alone.
The researchers collaborated with Tagide DeCarvalho, director of UMBC’s Keith Porter Imaging Facility, to obtain high-resolution imaging that confirms these close partnerships. The facility’s upgraded software allowed the team to capture ultrathin digital slices (0.2 microns thick) and create 3D reconstructions of neuron branches, clearly demonstrating that synapses are close enough to interact.
The study’s lead author, Ashley Copenhaver, Ph.D. ’25, Neuroscience and Cognitive Sciences, led much of the hands-on work on recording and imaging while mentoring members of the undergraduate team.
“One of the most exciting parts of this technically challenging project was performing dichromatic optogenetics during electrophysiology. I was literally able to shine small beams of red and blue light into the brain tissue, activate dorsal hippocampal neurons or ventral hippocampal neurons, and record the electrical responses of nucleus accumbens neurons. magical“In my opinion, not only do we love this technology, but we’ve identified some very important and fundamental mechanisms of signal integration in the brain.” I’m really excited to see where this work goes next. ”
From cells to behavior
Understanding how a single neuron processes signals from different areas of the brain is key to understanding complex behavior, says Le Gates, who also holds a post in the Department of Pharmacology and Physiology at the University of Maryland School of Medicine. Signals from the dorsal and ventral hippocampi “are probably more concentrated than we previously realized, and that could change the way people approach questions about motivation and learning,” she added.
This kind of convergence may help animals form associations between rewarding outcomes and the environments in which they occur, a capability essential for survival. Similar convergence has been seen in other brain regions involved in emotional learning, LeGates said, suggesting that the brain may widely use this strategy to associate specific situations with emotions and behaviors.
LeGates’ lab has already laid the groundwork for this paper by investigating how stress and substances such as food, medicines, and illicit drugs influence these same relationships, with the long-term goal of providing more targeted treatments for a variety of mental health conditions. In the near future, the research team aims to record the activity of these specially connected neurons during actual behavior and link the newly discovered crosstalk between the ventral and dorsal hippocampus directly to behavior.
By uncovering hidden layers of cooperation between hippocampal pathways, the LeGates lab has advanced our understanding of how the brain interweaves memory and motivation, fundamental processes that shape the decisions that drive our daily lives.
sauce:
University of Maryland, Baltimore County
Reference magazines:
Copenhaver, A.E.; Others. (2026). Heterosynaptic interactions between dorsal and ventral hippocampi in individual mesospinal neurons of the ventromedial shell of the nucleus accumbens. Journal of Neuroscience. DOI: 10.1523/JNEUROSCI.1225-25.2026. https://www.jneurosci.org/content/46/10/e1225252026
