Cortical activity reductions during repetition priming can result from rapid response learning

Abstract

Recent observation of objects speeds up their subsequent identification and classification. This common form of learning, known as repetition priming, can operate in the absence of explicit memory for earlier experiences, and functional neuroimaging has shown that object classification improved in this way is accompanied by 'neural priming' (reduced neural activity) in prefrontal, fusiform and other cortical regions. These observations have led to suggestions that cortical representations of items undergo 'tuning', whereby neurons encoding irrelevant information respond less as a given object is observed repeatedly, thereby facilitating future availability of pertinent object knowledge. Here we provide experimental support for an alternative hypothesis, in which reduced cortical activity occurs because subjects rapidly learn their previous responses. After a primed object classification (such as 'bigger than a shoebox'), cue reversal ('smaller than a shoebox') greatly slowed performance and completely eliminated neural priming in fusiform cortex, which suggests that these cortical item representations were no more available for primed objects than they were for new objects. In contrast, prefrontal cortex activity tracked behavioural priming and predicted the degree to which cue reversal would slow down object classification--highlighting the role of the prefrontal cortex in executive control.

Global familiarity of visual stimuli affects repetition-related neural plasticity but not repetition priming

“…Consistent with this idea, large RS was also found in premotor cortex (BA 6), a region that is important for planning movements and that receives strong inputs from the superior parietal lobule (Schubotz & von Cramon, 2003;Wise, Boussaoud, Johnson, & Caminiti, 1997). The presence of large RS effects in the superior parietal lobule and premotor cortex is consistent with the view that priming may not only reflect more efficient processing of the perceptual and semantic properties of stimuli, but also greater efficiency in linking a particular decision (Schnyer, Dobbins, Nicholls, Schacter, & Verfaellie, 2006) and/or motor response (Dobbins et al, 2004) to a repeated stimulus. This interpretation is consistent with recent findings showing a correlation between repetition priming and RS in precentral gyrus (Orfanidou et al, 2006) and superior parietal lobule (Habeck et al, 2006).…”

“…The first latent pattern, thresholded for descriptive purposes, is depicted in Figure 5. Many of those regions with strong RS contributions have previously been reported to show RS in repetition priming tasks (Dobbins et al, 2004;Habeck et al, 2006;Maccotta & Buckner, 2004;Simons et al, 2003). See Table 1 for a list of RS and RE contribution maxima and Figure 6 for a horizontal slice through occipital-temporal cortex showing regions with a large RS contribution to latent spatial pattern 1.…”

“…This is thought to reflect the increased efficiency in the neural processing of a repeated stimulus, which leads to behavioral priming. Going against both models, there have been a few reports of dissociations between repetition priming and RS in occipital-temporal cortex, as measured by fMRI (Dobbins, Schnyer, Verfaellie, & Schacter, 2004;Sayres & Grill-Spector, 2006). This suggests that not all aspects of RS may be directly related to repetition priming and that further research is necessary to determine the precise relationship between them.…”

Aging Influences the Neural Correlates of Lexical Decision but Not Automatic Semantic Priming

“…The different anatomical foci of these findings likely relate to the differing emphasis on automatic versus strategic processes. Repetition priming can be based in part upon learning of stimulus--response associations and can thus be susceptible to strategic inhibitory effects (Dobbins et al 2004). In contrast, semantic priming at short SOA such as the one used here (SOA = 250 ms) is thought to be dominated by automatic facilitation processes because insufficient time is available to predict the target based upon the prime (Posner and Snyder 1975;Neely 1977).…”

Retrieval of bindings between task-irrelevant stimuli and responses can facilitate behaviour under conditions of high response certainty

“…Much of the literature has focused on S-R effects for attended task-relevant stimuli. At one end of the spectrum, they have been shown to last across many minutes and intervening stimuli in the case of perceptual or semantic classification of objects (e.g., Denkinger & Koutstaal, 2009;Dobbins, Schnyer, Verfaellie, & Schacter, 2004;Horner & Henson, 2008;Soldan, Clarke, Colleran, & Kuras, 2012;Waszak & Hommel, 2007), words (e.g., Dennis & Schmidt, 2003;Race et al, 2009), and faces (Valt, Klein, & Boehm, 2014). At the other end, S-R effects have been shown under immediate repetition conditions (i.e., no intervening stimuli) for simplistic stimuli (e.g., single X or O letters) under simple classification tasks (e.g., is the stimulus an X or O; Hommel, 1998;Hommel & Colzato, 2004).…”