Brain Health Blog

Elizabeth Buchen, neuroscientist, science writer and advisor to Lumos Labs, explains why working memory is such a critical cognitive process, and how it works:

In an earlier post, I described the cognitive process of “attention,” which allows the brain to manage the surfeit of the world’s information by selecting only the most relevant information at any one time. What happens to this information once it successfully passes through the attentional funnel?

If cognitive processing ended at attention, you would conduct your life strictly from information received at the present instant, without any internal state of the mind or abstract thought. The words of this sentence would dart ephemerally in and out of your brain, becoming wholly devoid of perceptible meaning…

Instead of this mercifully unlikely scenario, however, your attention grants the words access to your brain’s working memory, which briefly holds and evaluates them for the duration of their relevance (i.e. until you have finished the sentence or idea).

Working memory, though operating over a timescale of mere seconds, is central to human thought processes. It allows you to temporarily hold and evaluate information in your mind, whether from the environment, stored memories, or internal state, thus allowing you to process the world within your personal context. Thus, working memory not only allows you to remember a phone number and find your way home, but is also central to language, reasoning, and most of the mental functions associated with human intelligence.

So what is the neural manifestation of this extraordinary ability? Working memory requires cooperation between multiple brain areas (depending on whether the information comprises locations, objects, or words), but the critical orchestrating structure is the prefrontal cortex (PFC). Lying directly behind the forehead at the front of the brain, the PFC contains neurons that exhibit the special properties of working memory; that is, they are activated by a specific stimulus, and remain activated for the duration of the stimulus’s relevance.

Consider, for example, the Lumosity Birdwatching game. When the bird flashes onto the screen, a certain population of neurons in your PFC will experience a surge in electrical activity. Importantly, these neurons will continue to fire at this elevated rate even after the bird disappears, allowing you to maintain a memory of the location while you move your mouse cursor to the proper location and “take a picture.” Moreover, in a different location of your PFC, another set of neurons remembers the letter that flashed in the middle of the screen, remaining electrically activated during the same time period.

The activity of these neurons allows you to maintain the bird’s location in your mind even when the visual stimulus is gone, exploiting the basic, fundamental mechanisms of your working memory. In your daily life, these mechanisms allow you to evaluate and manipulate select information from the world in the framework of your internal state and stored memories. Accordingly, working memory is crucial for effective decision-making and for the elaboration of goals and intentions; it enables you to manipulate abstract ideas, form coherent lines of reasoning, and overall act like the intelligent being you are.