Alpha/Beta Oscillations Indicate Inhibition of Interfering Visual Memories

Abstract

Selective retrieval of a specific target memory often leads to the forgetting of related but irrelevant memories. Current cognitive theory states that such retrieval-induced forgetting arises due to inhibition of competing memory traces. To date, however, direct neural evidence for this claim has not been forthcoming. Studies on selective attention suggest that cortical inhibition is mediated by increased brain oscillatory activity in the alpha/beta frequency band. The present study, testing 18 human subjects, investigated whether these mechanisms can be generalized to selective memory retrieval in which competing memories interfere with the retrieval of a target memory. Our experiment was designed so that each cue used to search memory was associated with a target memory and a competitor memory stored in separate brain hemispheres. Retrieval-induced forgetting was observed in a condition in which the competitor memory interfered with target retrieval. Increased oscillatory alpha/beta power was observed over the hemisphere housing the sensory representation of the competitor memory trace and predicted the amount of retrieval-induced forgetting in the subsequent memory test. These results provide the first direct evidence for inhibition of competing memories during episodic memory retrieval and suggest that competitive retrieval is governed by inhibitory mechanisms similar to those employed in selective attention.

Alpha oscillations during incidental encoding predict subsequent memory for new “foil” information

“…The current time-frequency results in combination with previous research indicate that neural oscillations are a useful tool for studying the temporal dynamics of encoding retrieval overlap (Jafarpour et al, 2014;Staresina et al, 2016;Staudigl & Hanslmayr, 2013;Staudigl et al, 2015;Waldhauser et al, 2012;Waldhauser et al, 2016). Burke et al (2013), for example, found that high gamma activity (44-100Hz) during successful encoding of information is also observed in similar brain areas during the memory test phase in which previously studied items need to be recalled.…”

Recognition-induced forgetting is not due to category-based set size

“…First, it has been well established that memory for pictures is better than memory for words (Durso & O'Sullivan, 1983;Gehring, Toglia, & Kimble, 1976;Hockley, 2008;Juola, Taylor, & Young, 1974;Madigan, 1974;Nelson, Reed, & McEvoy, 1977;Nelson, Reed, & Walling, 1976;Paivio & Csapo, 1973;Paivio, Rogers, & Smythe, 1968;Snodgrass & Burns, 1978;Snodgrass, Volvovitz, & Walfish, 1972;Snodgrass, Wasser, Finkelstein, & Goldberg, 1974), despite considerably more of the existing research on long-term memory having been conducted using verbal stimuli (Palmer, 1999). This led Maxcey and Woodman to predict that memory for pictoral stimuli in visual long-term memory would be immune to forgetting effects shown with words (e.g., retrieval-induced forgetting) and thus unimpaired following recognition practice (see also Ciranni & Shimamura, 1999;Fan & Turk-Browne, 2013;Shaw, Bjork, & Handal, 1995;Waldhauser, Johansson, & Hanslmayr, 2012). Contrary to their prediction, practice recognizing pictoral stimuli led to the forgetting of related stimuli.…”

Age-related changes in neural oscillations supporting context memory retrieval

“…Alpha and beta power decreases have also been linked to successful episodic memory retrieval in several studies (Duzel et al, 2010; Hanslmayr et al, 2012 for reviews). Alpha and beta power decreases as the number of retrieved items increases and varies spatially across the scalp according to the type of perceptual features associated with prior encoded events (Khader & Rosler, 2011; Waldhauser, Braun, & Hanslmayr, 2016; Waldhauser, Johansson, & Hanslmayr, 2012). …”