Neurological Basis of Decision-Making Shown by Brain Mapping in Rats

Mapping the brain and uncovering its very complex mechanisms is one of the biggest scientific projects, and it sees progress and breakthroughs every single day. After several years of research, a team of UC San Francisco scientists presented their discoveries how memory recall is linked to decision-making in rats, showing that activity in the hippocampus occurs when rats in a maze are playing out memories that help them decide which way to turn.

Importantly it could be experimentally shown that the more they play out these memories, the more likely they are to find their way correctly to the end of the maze.

The way to observe this was by implanting electrodes directly on the hippocampus, which is located deep within the brain and plays a central role in the formation and recall of memory. This region is also active when animals are learning, and it is damaged in people who have Alzheimer's and post-traumatic stress disorder.

The tools to observe brain activity, and single neurons indeed, are rapidly developing and become ever more compact and precise, resulting in implantable micro-chips that track neuronal activity. These advancements are crucial to narrow down the understanding of the brain, and also to shift research from animal brains to the human brain which is both more complex and sensitive.

The present study showed that when the rats paused before an upcoming choice, sometimes the hippocampus was more active and sometimes it was less active. When it was more active it did a better job of recalling memories of places the animal could go next, and the animal was more likely to go to the right place.

"We know that considering possibilities is important for decision-making, but we haven't really known how this happens in the brain," said neuroscientist Loren Frank, PhD, who led the research.

The work builds upon several years of investigations in Frank's laboratory that have shown how activity in the hippocampus is a fundamental constituent of memory retrieval. Their recent work shows that this activity is not just about remembering the past - it is also important for thinking about the future. When the brain does a better job of thinking about future possibilities, it makes better decisions.

The team said that their next steps would be to work out why sometimes the hippocampus does not do a good job of playing out future options. Problems with memory and decision-making are central to age-related cognitive decline, and a deeper understanding of how this works could pave the way for interventions that make the brain work better.

Study:

Annabelle C. Singer et al., Hippocampal SWR Activity Predicts Correct Decisions during the Initial Learning of an Alternation Task, Neuron, 2013, doi: 10.1016/j.neuron.2013.01.02