No abstract

It is widely assumed that the short-term retention of information is accomplished via maintenance of an active neural trace. However, we demonstrate that memory can be preserved across a brief delay despite the apparent loss of sustained representations. Delay-period activity may in fact reflect the focus of attention, rather than short-term memory. We unconfounded attention and memory by causing external and internal shifts of attention away from items that were being actively retained. Multivariate pattern analysis of fMRI indicated that only items within the focus of attention elicited an active neural trace. Activity corresponding to representations of items outside the focus quickly dropped to baseline. Nevertheless, this information was remembered after a brief delay. Our data also show that refocusing attention towards a previously unattended memory item can reactivate its neural signature. The loss of sustained activity has long been thought to indicate a disruption of short-term memory, but our results suggest that, even for small memory loads not exceeding the capacity limits of short-term memory, the active maintenance of a stimulus representation may not be necessary for its short-term retention.

Neurofeedback has begun to attract the attention and scrutiny of the scientific and medical mainstream. Here, neurofeedback researchers present a consensus-derived checklist that aims to improve the reporting and experimental design standards in the field.

For decades, it has been assumed that sustained, elevated neural activity – the so-called active trace – is the neural correlate of the short-term retention of information. However, a recent functional magnetic resonance imaging (fMRI) study has suggested that this activity may be more related to attention than retention. Specifically, a multivariate pattern analysis (MVPA) failed to find evidence that information that was outside the focus of attention, but nonetheless in short-term memory (STM), was retained in an active state. Here, we replicate and extend this finding by querying the neural signatures of attended vs. unattended information within STM with electroencephalograpy (EEG), a method sensitive to oscillatory neural activity. We demonstrate that in the delay-period EEG activity, there is information only about memory items which are also in the focus of attention. Information about items outside the focus of attention is not present. This result converges with the fMRI findings to suggest that, contrary to conventional wisdom, an active memory trace may be unnecessary for the short-term retention of information.

Significance Forgetting is often considered to be bad, but selective forgetting of unreliable information can have the positive side effect of reducing mental clutter, thereby making it easier to access our most important memories. Prior studies of forgetting have focused on passive mechanisms (decay, interference) or on effortful inhibition by cognitive control. Here we report the discovery of an active mechanism for forgetting that weakens memories selectively and without burdening the conscious mind. Specifically, we show that the brain automatically generates predictions about which items should appear in familiar contexts; if these items fail to appear, their memories are weakened. This process is adaptive, because such memories may have been encoded incorrectly or may represent unstable aspects of the world.