Stimulus-driven changes in the direction of neural priming during visual word recognition

Abstract

Visual object recognition is generally known to be facilitated when targets are preceded by the same or relevant stimuli. For written words, however, the beneficial effect of priming can be reversed when primes and targets share initial syllables (e.g., "boca" and "bono"). Using fMRI, the present study explored neuroanatomical correlates of this negative syllabic priming. In each trial, participants made semantic judgment about a centrally presented target, which was preceded by a masked prime flashed either to the left or right visual field. We observed that the inhibitory priming during reading was associated with a left-lateralized effect of repetition enhancement in the inferior frontal gyrus (IFG), rather than repetition suppression in the ventral visual region previously associated with facilitatory behavioral priming. We further performed a second fMRI experiment using a classical whole-word repetition priming paradigm with the same hemifield procedure and task instruction, and obtained well-known effects of repetition suppression in the left occipito-temporal cortex. These results therefore suggest that the left IFG constitutes a fast word processing system distinct from the posterior visual word-form system and that the directions of repetition effects can change with intrinsic properties of stimuli even when participants' cognitive and attentional states are kept constant.

Left Amygdala Regulates the Cerebral Reading Network During Fast Emotion Word Processing

“…Specifically, the ventrolateral prefrontal region, which showed the highest effect of priming × valence interaction (see Table 2 and Figure 3), is known to receive inputs from the amygdala and play a role in regulating negative emotion (Quirk and Beer, 2006;Ray and Zald, 2012). This ventrolateral IFG may be also involved in switching the directions of fMRI priming according to the semantic content of visual stimuli (Pas et al, 2016). Moreover, the basal amygdala targeted in the present ROI analyses has dense reciprocal projections via the uncinate fasciculus to the orbital part of the IFG (Salzman and Fusi, 2010;Thiebaut de Schotten et al, 2012), i.e., an inferior frontal subregion which showed strong prime-by-valence interaction (see section "Results").…”

“…Our ROI analyses further showed significant valence x priming interaction in the bilateral amygdala (Figure 4), indicating the same trend of suppression and enhancement as the one seen in the left-hemisphere reading network. While the precise neurophysiological basis of repetition suppression and enhancement is an issue of controversy in neuroimaging research (Segaert et al, 2013;Barron et al, 2016;Henson, 2016), the direction of fMRI priming is known to change at different levels of word processing, e.g., lexicosemantic relations (Raposo et al, 2006;Pas et al, 2016), task requirements (Nakamura et al, 2007), and visibility of stimuli Qiao et al, 2010).…”

“…Participants determined whether visible targets represented concrete objects or abstract concepts. effects of behavioral and fMRI priming can be obtained with masked words in parafoveal vision (Nakamura et al, 2012b;Pas et al, 2016) and (2) the present level of prime duration still allows assessing early and automatic stages of reading (Greenwald et al, 1996;Qiao et al, 2010;Nakamura et al, 2012a). On each trial, participants decided as quickly and accurately as possible whether targets represented concrete objects or abstract concepts by pressing keys with their left and right thumbs.…”

“…Several past studies used similar hemifield paradigms to explore hemispheric lateralization during affective processing (Williams and Mattingley, 2004;Noesselt et al, 2005;Landis, 2006;Rochas et al, 2014). By delivering masked prime stimuli briefly to each hemifield, this priming paradigm enabled us to stimulate each hemispheric system separately during the early, automatic stage of word processing, since weak neural activation induced by such degraded primes occurs locally within each hemisphere and does not spread across hemispheres (Reynvoet and Ratinckx, 2004;Pas et al, 2016). We further performed functional connectivity analysis to assess long-distance interactions between the amygdala and the left-hemisphere reading network.…”

Power spectrum scale invariance as a neural marker of cocaine misuse and altered cognitive control

“…The IFG is part of the ventral attention system, which activates to the detection of a salient, behaviorally relevant target (for review, see ( Corbetta et al, 2008 ). Although the bulk of this literature has focused on the role of the right IFG in attention ( Hampshire, A., et al, 2010 , Konishi, S., et al, 1999 ) and its link to response inhibition ( Chao, H.H., et al, 2009 , Duann, J.R., et al, 2009 , Erika-Florence, M., et al, 2014 ), studies have implicated the left IFG in attentional processes including responses to mismatch negativity ( Hedge et al, 2015 ), as well as to repetition priming during word recognition ( Pas, M., et al, 2015 , Thiel, A., et al, 2005 ) and sound tone identification ( Asaridou et al, 2015 ). The left IFG responds to the resolution of semantic conflicts between linguistic inputs ( Ye and Zhou, 2009 ).…”