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You take the same route to work every day, driving the same car, crossing the same intersection with the same median strip. Same old, same old. But this morning something new catches your eye: a cow grazing in the median. It takes a couple of honks to remind you that the light has turned green.
If you are like most people, you will remember this moment in your morning commute for a long time—the sun was shining, daffodils had just pushed up in the median, and “We Are the Champions” was playing on the radio. Yet all the other countless times you have driven through this intersection are long forgotten.
Psychologists have known for some time that if we experience a novel situation within a familiar context, we will more easily store this event in memory. But only recently have studies of the brain begun to explain how this process happens and to suggest new ways of teaching that could improve learning and memory.
One of the most important brain regions involved in discovering, processing and storing new sensory impressions is the hippocampus, located in the temporal lobe of the cerebral cortex. Novel stimuli tend to activate the hippocampus more than familiar stimuli do, which is why the hippocampus serves as the brain’s “novelty detector.”
The hippocampus compares incoming sensory information with stored knowledge. If these differ, the hippocampus sends a pulse of the messenger substance dopamine to the substantia nigra (SN) and ventral tegmental area (VTA) in the midbrain. From there nerve fibers extend back to the hippocampus and trigger the release of more dopamine. Researchers, including John Lisman of Brandeis University and Anthony Grace of the University of Pittsburgh, call this feedback mechanism the hippocampal-SN/VTA loop (above right).
This feedback loop is why we remember things better in the context of novelty. As Shaomin Li and his colleagues at Trinity College Dublin discovered in 2003, the release of dopamine in the hippocampus of rats activates the synapses among nerve cells, creating stronger connections that lead to long-term memory storage. We wondered whether this same neuronal loop facilitates the retention of other information that is perceived along with novel stimuli.
At the University of Magdeburg’s Institute for Cognitive Neurology, in collaboration with Emrah Düzel and Nico Bunzeck of University College London, we used functional magnetic resonance imaging to measure the activity of various brain regions based on blood flow. We presented one group of test subjects with a set of already known images and a second group with a combination of known and new images. Subjects in the second group were better at remembering the images than subjects in the first group were, and the fMRI data showed greater activity in the SN and VTA areas of the brain when the subjects were viewing unfamiliar images. This correlation may help explain how novelty improves memory.
Are the effects of novelty on memory merely temporary? To answer this question, we showed test subjects a variety of photographs and measured their brain activity using fMRI. We also gave the participants a series of words to sort according to their meaning.
The experiment continued the next day when we showed some of the test subjects new images while others viewed familiar ones. Then we asked all the subjects to recall as many words from the previous day’s exercise as they could. Recall was significantly better in the group that had just viewed new images.
In other words, novelty seems to promote memory. This finding gives teachers a potential tool for structuring their lessons more effectively. Although most teachers start a lesson by going over material from the previous class before moving on to new subject matter, they should probably do just the opposite: start with surprising new information and then review the older material.