Stress can be a very usefull mechanism to improve our concentration, focus and power at certain moments. On the other hand, everybody also knows the feeling that, due to stress, one tends to be more forgetful and distracted in other tasks. You forget, for example, a short meeting with a colleague, or you don’t remember where you put your keys.
New research, published last week in PLOS Computational Biology, reveals how this is possible. It turns out that stress influences how our short-term memory works. This memory system, situated in the prefrontal cortex, helps us to temporarily remember large amounts of perceived information. It stores the first part of this sentence, so that you can finish reading it without forgetting the first half again. After one to one-an-a-half second, the information in the neurons is erased and replaced by something new that attracts our attention. It thus helps us to complete tasks that seem so simple: you can actually do them without thinking about it.
Researchers Devilbiss, Jenison and Berridge found out that for neuron cells in the prefrontal cortex to keep this stored information ‘at hand’, they have to keep on firing and re-firing. Berridge explains: “Even though these neurons communicate on a scale of every thousandth of a second, they know what they did one second to one-and-a-half seconds ago. But if the neuron doesn’t stimulate itself again within a little more than a second, it’s lost that information.”
When stress was applied to test rats, the researchers found that this caused the neurons in the short-term memory to interrupt this firing cycle. In other words, the neurons stopped reminding themselves what they had to remember. This led the researchers to the conclusion that stress significantly impairs our short-term memory capacities and thereby turns us into entangled stress sufferers, looking for our keys while we try to remember what to bring from the grocery store.
Devilbiss D.M., Jenison R.L., Berridge C.W. (2012). Stress-Induced Impairment of a Working Memory Task: Role of Spiking Rate and Spiking History Predicted Discharge PLoS Comput Biol : doi:10.1371/journal.pcbi.1002681