When we pause to contemplate before making a significant choice, we often envisage various potential outcomes from our options. This “mental simulation” process is fundamental to our everyday decision-making and planning, yet the underlying brain functions remain largely elusive.
International researchers have recently made significant strides in identifying the neural processes involved in planning. Their findings, detailed in Nature Neuroscience, significantly contribute to our understanding of decision-making. They indicate a dynamic interaction between the brain’s prefrontal cortex and hippocampus, enabling us to foresee and evaluate future possibilities to inform our decisions better.
Marcelo Mattar, an assistant professor at New York University’s Department of Psychology and co-author of the study, describes the prefrontal cortex as functioning akin to a ‘simulator’. It mentally explores various scenarios utilising a cognitive map held within the hippocampus. According to Mattar, this investigation highlights the intricate neural and cognitive frameworks underpinning planning, a critical aspect of intelligence in both humans and animals. Enhancing our understanding of these mechanisms could have profound implications for treating conditions that impair decision-making capabilities, offering hope for those affected.
The prefrontal cortex and hippocampus play crucial roles in planning and memory. However, their exact contributions to deliberative decision-making, where careful consideration is required before action, still need to be fully understood.
To probe these neural underpinnings further, Mattar, along with Kristopher Jensen, a computational neuroscientist at University College London, and Guillaume Hennequin, a professor at the University of Cambridge, developed a computational model to simulate brain activity during the planning process. Their collaborative effort, a recurrent neural network (RNN) that adapts based on incoming data, incorporates established theories of planning and introduces complex new elements, such as ‘imagined actions’. This approach is akin to a chess player contemplating a series of moves before deciding, thereby encapsulating how decision-making typically involves assessing the repercussions of various options.
The team validated their model through experiments with humans and laboratory rats, assessing its predictive accuracy against actual behavioural and neural data. They designed a novel experiment in which humans navigated a virtual maze on a computer screen, measuring the time they took to contemplate each move. They compared these findings with neural recordings from rats navigating a similarly configured physical maze, aligning human and animal data to draw comprehensive insights from both.
The results confirmed the validity of the computational model, illustrating a complex interaction between the prefrontal cortex and hippocampus during planning. In human subjects, increased brain activity was observed when participants took longer to consider their moves through the maze. Similarly, the neural responses of rats traversing the maze mirrored the model’s predictions.
Mattar notes that this research sheds light on the brain circuits that allow us to reflect before acting and provides a novel methodological approach by aligning tasks across human and animal studies and computational models. This innovative methodology offers a robust framework for gaining deeper insights into behaviour, reinforcing foundational knowledge about strategic decisions.
More information: Kristopher T. Jensen et al, A recurrent network model of planning explains hippocampal replay and human behavior, Nature Neuroscience. DOI: 10.1038/s41593-024-01675-7
Journal information: Nature Neuroscience Provided by New York University
