Repetition priming and cortical arousal in healthy aging and Alzheimer's disease

Abstract

Repetition priming refers to a form of implicit memory in which prior exposure to a stimulus facilitates the subsequent processing of the same or a related stimulus. One frequently used repetition priming task is word-stem completion priming. In this task, participants complete a series of beginning word stems with the first word that comes to mind after having viewed, in an unrelated context, words that can complete some of the stems. Patients with Alzheimer’s disease (AD) exhibit a significant deficit in word-stem completion priming, but the neural mechanisms underlying this deficit have yet to be identified. The present study examined the possibility that the word-stem completion priming deficit in AD is due to disruption of ascending neuromodulatory systems that mediate cortical arousal by comparing word-stem completion priming and behavioral measures of spatial orienting and phasic alerting. Results showed that in healthy elderly controls higher levels of phasic alerting were associated with a sharpening of the temporal dynamics of priming across two delay intervals: those with higher levels of alerting showed more immediate priming but less delayed priming than those with lesser levels of alerting. In patients with AD, priming was impaired despite intact levels of phasic alerting and spatial orienting, and group status rather than individual levels of alerting or orienting predicted the magnitude of their stem-completion priming. Furthermore, the change in priming across delays they displayed was not related to level of alerting or orienting. These findings support the role of the noradrenergic projection system in modulating the level of steady-state cortical activation (or “cortical tonus”) underlying both phasic alerting and the temporal dynamics of repetition priming. However, impaired priming in patients with AD does not appear to be due to disruption of this neuromodulatory system.

Repetition Priming in Individuals with Amnestic Mild Cognitive Impairment and Alzheimer’s Dementia: a Systematic Review and Meta-Analysis

“…As can be seen in Table 3 , the priming Z-scores were quite similar across the moderator. Further, authors of all articles that did not report statistics that allowed for the calculation of Z -scores reported that a priming effect was present for both (Bäckman et al, 1997 ; Carlesimo et al, 1995 ; Gabrieli et al, 1999a , b ; Kane et al, 2015 ; Lazzara et al, 2001 ; Passafiume et al, 2006 ; Randolph, 1991 ; Salmon et al, 1988 ) or one (Bondi & Kaszniak, 1991 ) of the groups.…”

“…The results reported in two dissertations were later published in peer reviewed journals. In these specific instances, the published results were used rather than the dissertations themselves, which were excluded to avoid repeated results within the meta-analytic model (Kane et al, 2015 ; Norton & Ostergaard, 2001 ), unless results on an additional task was reported in the dissertation but not in the published manuscript, in which case the results of the task that was not published were included from the dissertation (Kane, 2009 ). For studies that appeared to be from the same research group, authors were contacted to assess whether the study samples of these studies had overlap.…”

Word Priming and Interference Paradigms

“…Similarly, priming studies have implemented many different types of prime-target relationships. In addition to a substantial body of studies using various types of meaning-related prime-target pairs, there are numerous studies that used morphologically related pairs (e.g., related verb forms as in "fall -fell," Crepaldi, Rastle, Coltheart, & Nickels, 2010; or stems and compounds as in "butter -butter dish," Lüttmann et al, 2011), orthographically related pairs (e.g., "castfe -castle," Adelman et al, 2014), phonologically related pairs (e.g., "ma -mama," Becker, Schild, & Friedrich, 2014), and identical pairs (Kane et al, 2015). In most studies prime and target appear in the same language, but studies of word processing in bilingual speakers often present primes and targets in different languages (Wang, 2013).…”