You're trying not to think about the argument you had this morning, but vivid images keep popping into your head. At the same time, you're preparing a report and holding numbers in your mind. It doesn't go well: memory interferes with work, and work prevents forgetting. Scientists set out to see how the brain copes with this dual load in people with varying levels of anxiety.
In the experiment, 47 healthy volunteers took part. They were shown pleasant and unpleasant images, then asked to either recall or suppress the memory of each picture. Simultaneously, they performed a second task — holding a visual pattern in memory. The researchers measured how successfully participants controlled their memories and also scanned their brains at rest to examine connections between brain regions.
But the brain networks differed. When people suppressed pleasant memories, the connection between the anterior cingulate cortex (which handles control) and posterior perceptual areas weakened, as did the link between the hippocampus (the memory storehouse) and the frontal pole. When suppressing unpleasant memories, the connection between the parietal and occipital regions strengthened. Anxiety meddled in these processes: in more anxious individuals, the prefrontal cortex worked differently when suppressing positive images and when recalling positive and neutral ones.
It seems the brain processes pleasant and unpleasant memories differently when you need to hold something else in mind at the same time. Anxiety selectively alters these networks, which could explain why anxious people find it harder to shake off intrusive thoughts about both good and bad things.
The hippocampus, a brain region named after the seahorse due to its shape, plays a key role in transferring memories from short-term to long-term storage.