Pattern Of Priming Research Articles

Nicotine effects on general semantic priming in Parkinson's disease.

In young healthy nonsmokers, effects of nicotine on semantic processing have been observed under strategy-based priming procedures but not under more general priming procedures (Holmes, Chenery, & Copland, 2008; Holmes, Chenery, & Copland, 2010). Effects of nicotine under general priming procedures, however, may be mediated by baseline priming levels that are below optimum such as when compromised by disease. Nicotinic mechanisms may be involved in the cognitive sequalae of Parkinson's disease (PD). Evidence suggests that semantic processing may be compromised in PD but the potential benefit of nicotinic stimulation is unknown. This study investigated the effects of nicotine on semantic processing in nonsmokers with PD (n = 12) and nonsmoking matched controls (n = 17) using general priming procedures. Specifically, an automatic priming task (0.15 relatedness proportion, RP, and 200 ms stimulus onset asynchrony, SOA) and a controlled priming task (0.8 RP and 1000 ms SOA) were used. Prime-target category relation (category related, noncategory related) was also manipulated. Transdermal nicotine patches (7 mg/24 h) were administered in a double-blind, placebo-controlled, crossover design. For the automatic task, nicotine did not influence priming effects for PD. Unexpectedly, compromised automatic priming for controls was ameliorated. For the controlled task, nicotine influenced priming effects for PD but not controls. The patterns of priming and nicotine effects across the tasks suggest an age-related slowing of the rate of semantic activation for controls, which may be exacerbated in PD. Overall, the findings indicate that nicotine can improve compromised semantic processing in PD, and also influence semantic processing in healthy older individuals.

Symmetrical hemispheric priming in spatial neglect: A hyperactive left-hemisphere phenomenon?

Hemispheric rivalry models of spatial neglect suggest that the left hemisphere becomes hyperactive following right-hemisphere lesions since the two hemispheres normally exert an inhibitory influence on each other via callosal connections. Using a masked hemifield priming paradigm, we investigated whether the putative change in hemispheric balance involves other, higher-order abstract representational systems in spatial neglect. Participants consisted of 12 neglect patients with right-hemisphere damage and three groups of control participants, i.e., 12 young healthy controls, 10 age-matched healthy controls and 10 right-hemisphere patients without spatial neglect. In each trial, participants made semantic categorization about a centrally presented target word which was preceded by a masked prime flashed either to the left or right visual field. All three control groups exhibited strong left-hemisphere advantage in inhibitory syllabic priming, consistent with the known left-hemisphere dominance in lexical inhibition during reading. By contrast, neglect patients exhibited a symmetrical pattern of priming between the left and right visual fields. These results suggest that (1) the neglected hemifield can rapidly extract abstract information even from weak and normally non-perceptible visual stimuli, but that (2) the normal left hemispheric dominance in reading is absent in neglect patients probably because of the generalized hyperactivity of the left hemisphere. Our results demonstrate a covert behavioral change in spatial neglect which may reflect the altered inter-hemispheric balance in the bilateral word recognition system encompassing lexico-semantic memory.

Opposing patterns of neural priming in same-exemplar vs. different-exemplar repetition predict subsequent memory

The present neuroimaging study examines how repetition-related neural attenuation effects differ as a function of the perceptual similarity of the repetition and subsequent memory. One previous study (Turk-Browne et al., 2006) reported greater attenuation effects for subsequent hits than for misses. Another study (Wagner et al., 2000) found that neural attenuation is negatively correlated with subsequent memory. These opposing results suggest that repetition-related neural attenuation for subsequent hits and misses may be driven by different factors. In order to investigate the factors that affect the degree of neural attenuation, we varied perceptual similarity between repetitions in a scanned encoding phase that was followed by a subsequent memory test outside the scanner. We demonstrated that the degree of neural attenuation in the object processing regions depends on the interaction between perceptual similarity across repeated presentations and the quality their encodings. Specifically, the same areas that decreased neural signal for repetitions of same exemplars that were subsequently recognized with confidence that the repetitions were identical showed a decrease in neural signal for different-exemplar misses but not for the corresponding subsequently recognized hits. Our results imply that repetition-related neural attenuation should be related to the more efficient processing of perceptual properties of the stimuli only if subjects are able to subsequently remember the stimuli. Otherwise, the cause of attenuation may be in the failure to encode the stimuli on the second presentation as shown by the pattern of neural attenuation for the different-exemplar misses.

Processing words in two languages: An event-related brain potential study of proficient bilinguals

In a previous study of native-English speaking university learners of a second language (Spanish) we observed an asymmetric pattern of ERP translation priming effects in L1 and L2 ( Alvarez, Holcomb, & Grainger, 2003, Brain & Language, 87, 290–304) with larger and earlier priming on the N400 component in the L2 to L1, compared with the L1 to L2 direction. In the current study 20 native-Russian speakers who were also highly proficient in English participated in a mixed-language lexical decision task in which critical words were presented in Russian (L1) and English (L2) and repetitions of these words (within and between languages) were presented on subsequent trials. ERPs were recorded to all items allowing for comparisons of repetition effects within and between (translation) languages. The results revealed a symmetrical pattern of within-language repetition and between-language translation ERP priming effects, which in conjunction with Alvarez et al. (2003), supports the hypothesis that L2 proficiency level rather than age or order of language acquisition is responsible for the observed patterns of translation priming. The ramifications of these results for models of bilingual word processing are discussed.

BH3 Profiling Demonstrates Decreased Mitochondrial Priming for Apoptosis In Primary CLL Cells Exposed to Stroma

AbstractAbstract 692Treatments for chronic lymphocytic leukemia (CLL) often kill malignant cells in the peripheral blood, but the disease inevitably relapses in the lymph nodes or bone marrow. BH3 profiling was developed in our laboratory to assess the degree to which malignant cells are primed to undergo apoptosis by the mitochondrial pathway, and to identify the anti-apoptotic proteins on which these cells depend for their survival. We hypothesized that BH3 profiling can help elucidate mechanisms underlying stromal-mediated resistance to the BH3-mimetic ABT-737 in CLL. BH3 profiling was performed by exposing malignant CD19+ B cells from 15 CLL patients to a panel of BH3-domain peptides, and the cell death induced was quantified by JC-1 based FACS to assess mitochondrial outer membrane permeabilization, as previously described (Ryan et al., PNAS 2010). To simulate lymph node and bone marrow microenvironments, we co-cultured CLL cells from a subset of these patients for 24 hours in the presence of IL-4 with CD154+ fibroblasts and with HS5 cells, respectively, and then repeated BH3 profiling. The status of the chemokine receptor CXCR4, which can serve as a marker for the residence of CLL cells in stromal microenvironments, was also evaluated by FACS. Additional co-culture experiments were done in the presence or absence of ABT-737 at 100 nM, and CLL cell viability was assessed at 24 hours by Annexin-PI. We also performed BH3 profiling on 7 additional CLL patients with matched peripheral blood, lymph node, and bone marrow samples. Circulating malignant CLL cells were highly primed to undergo apoptosis, and their survival was mainly dependent on Bcl-2, and to a lesser degree Mcl-1. CXCR4 decreased on CLL cells co-cultured for 24 hours with CD154+ fibroblasts (38.6%) compared to cells cultured with parental controls (76.3%) (p = 0.030), but did not decrease on cells cultured with HS5 cells (87.1%) (p > 0.05). When CLL cells were co-cultured with CD154+ fibroblasts in the presence of ABT-737, mean CLL cell viability by Annexin-PI increased to 85.1% compared to 31.8% (p < 0.001) in cells co-cultured with parental controls. BH3 profiling revealed that CD154+ fibroblast exposure led to decreased CLL cell mitochondrial depolarization in response to Bim, Noxa, Hrk, and particularly to ABT-737 (see figure). In contrast, CLL cells exposed to HS5 cells had unchanged CXCR4 status, but still had a decrease in apoptotic priming, which was observed in response to an even broader range of BH3-domain peptides, including Puma and Bmf. When gating on the whole CLL cell population, the pattern and degree of apoptotic priming was similar in matched peripheral blood, lymph node, and bone marrow biopsy samples from 7 additional patients. Interestingly, gating on CXCR4 status revealed heterogeneity in apoptotic priming in the different microenvironments, with a subset of patients showing that CXCR4- bone marrow-derived CLL cells were less primed than their CXCR4+ counterparts. Overall, BH3 profiling demonstrated that circulating primary CLL cells are highly primed to undergo apoptosis, and depend predominantly on the anti-apoptotic protein Bcl-2 for their survival. CLL cells co-cultured with lymph node-like stroma had decreased CXCR4 surface expression and became resistant to ABT-737. BH3 profiling demonstrated that this resistance was accompanied by decreased apoptotic priming in response to several BH3-domain peptides. An even broader decrease in apoptotic priming was observed in response to co-culture with a bone marrow-like microenvironment, apparently unrelated to changes in CXCR4 status. Matched peripheral blood, lymph node, and bone marrow CLL patient samples had similar BH3 profiles overall, but some patients showed decreased apoptotic priming in CXCR4- CLL cells, which likely represent the true bone marrow resident CLL cell population. This heterogeneity in mitochondrial priming may help to explain some of the resistance to therapy observed in bone marrow and lymph nodes as compared to peripheral blood. [Display omitted] Disclosures:Letai:Eutropics Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees.

Conceptual and perceptual priming and dissociation in chronic posttraumatic stress disorder.

Cognitive models of posttraumatic stress disorder (PTSD) assert that memory processes play a significant role in PTSD (see e.g., Ehlers & Clark, 2000). Intrusive reexperiencing in PTSD has been linked to perceptual processing of trauma-related material with a corresponding hypothesized lack of conceptual processing. In an experimental study that included clinical participants with and without PTSD (N = 50), perceptual priming and conceptual priming for trauma-related, general threat, and neutral words were investigated in a population with chronic trauma-induced complaints as a result of the Troubles in Northern Ireland. The study used a new version of the word-stem completion task (Michael, Ehlers, & Halligan, 2005) and a word-cue association task. It also assessed the role of dissociation in threat processing. Further evidence of enhanced perceptual priming in PTSD for trauma stimuli was found, along with evidence of lack of conceptual priming for such stimuli. Furthermore, this pattern of priming for trauma-related words was associated with PTSD severity, and state dissociation and PTSD group made significant contributions to predicting perceptual priming for trauma words. The findings shed light on the importance of state dissociation in trauma-related information processing and posttraumatic symptoms.

Priming effect of hearing‐impaired listeners in speech perception.

Unlike normal hearing (NH) listeners, the speech perception of hearing‐impaired (HI) listeners is much too complicated to be determined for certain. That is, HI listeners provide a varied profile of consonants that NH listeners record as 100% correct, with an error of less than 1/1000. Thus, we argue that there is an important factor that dominates the consonant errors in HI listeners: grouping errors, or priming. We hypothesize that when a cochlear dead region is present, a critical cue is lost, forcing priming errors (the listener cannot identify the sound within a group). We have tested over 50 sensorineural hearing‐impaired ears for consonant recognition both in quiet and in noise. Sixteen English CV syllables were analyzed. Preliminary results showed that there is a subject based trend for either temporal or spectral cue errors when explaining the priming pattern of HI ears. In particular, /ga/, /ba/, /Za/, and /sa/ were reported as /da/, /pa/, /Sa/, and /Ta/, respectively. Although more data collection and analysis will be needed to prove the current findings, we conclude that HI listeners hear the consonant feature differently from NH listeners. [Work supported by NIH Research Grant.]

What do fully visible primes and brain potentials reveal about morphological decomposition?

To examine the role of meaning in morphological decomposition ({re-}+{play}), researchers have employed the priming paradigm. Perceptually masked primes lead to facilitation both when decomposition is semantically appropriate (hunter-HUNT) and when it is not (corner-CORN), whereas with fully visible primes facilitation is observed only in the former case. We investigated the N400 brain potential time-locked to words preceded by fully visible primes. At ∼300-380 ms, N400 was equally attenuated in the semantically "transparent" condition (hunter-HUNT) and semantically "opaque" condition (corner-CORN). In the transparent condition, N400 remained attenuated after 380 ms, whereas in the opaque condition it returned to the level of a nonmorphological form condition (brothel-BROTH). This pattern of N400 priming is consistent with an orthography-based, morphological decomposition mechanism, "licensed" at a later stage by semantic information.

Place and summation coding for canonical and non-canonical finger numeral representations

Fingers can be used to express numerical magnitudes, and cultural habits about the fixed order in which fingers are raised determine which configurations become canonical and which non-canonical. Although both types of configuration carry magnitude information, it has been shown that the canonical ones are recognized faster and directly linked to number semantics. Here we tested whether this difference is a consequence of differences in the qualitative way of processing the two types of configurations. When participants named Arabic digits (Experiment 1) or verbal numerals (Experiment 2) primed by canonical and non-canonical finger configurations, qualitatively different priming patterns were observed for the two types of configurations. Canonical configurations activated a place coding representation, with priming spreading to close smaller and larger magnitudes as a function of the prime–target distance. Conversely, non-canonical configurations activated a summation coding representation priming smaller and equal magnitudes independently of the prime–target distance, and larger targets depending on this distance.

Motivational priming and processing interrupt: Startle reflex modulation during shallow and deep processing of emotional words

Valence-driven modulation of the startle reflex, that is larger eyeblinks during viewing of unpleasant pictures and inhibited blinks while viewing pleasant pictures, is well documented. The current study investigated, whether this motivational priming pattern also occurs during processing of unpleasant and pleasant words, and to what extent it is influenced by shallow vs. deep encoding of verbal stimuli. Emotional and neutral adjectives were presented for 5 s, and the acoustically elicited startle eyeblink response was measured while subjects memorized the words by means of shallow or deep processing strategies. Results showed blink potentiation to unpleasant and blink inhibition to pleasant adjectives in subjects using shallow encoding strategies. In subjects using deep-encoding strategies, blinks were larger for pleasant than unpleasant or neutral adjectives. In line with this, free recall of pleasant words was also better in subjects who engaged in deep processing. The results suggest that motivational priming holds as long as processing is perceptual. However, during deep processing the startle reflex appears to represent a measure of “processing interrupt”, facilitating blinks to those stimuli that are more deeply encoded.

Masked priming effect reflects evidence accumulated by the prime

In the same-different match task, masked priming is observed with the same responses but not different responses. Norris and Kinoshita's (2008) Bayesian reader account of masked priming explains this pattern based on the same principle as that explaining the absence of priming for nonwords in the lexical decision task. The pattern of priming follows from the way the model makes optimal decisions in the two tasks; priming does not depend on first activating the prime and then the target. An alternative explanation is in terms of a bias towards responding "same" that exactly counters the facilitatory effect of lexical access. The present study tested these two views by varying both the degree to which the prime predicts the response and the visibility of the prime. Unmasked primes produced effects expected from the view that priming is influenced by the degree to which the prime predicts the response. In contrast, with masked primes, the size of priming for the same response was completely unaffected by predictability. These results rule out response bias as an explanation of the absence of masked priming for different responses and, in turn, indicate that masked priming is not a consequence of automatic lexical access of the prime.

Where perception meets memory: A review of repetition priming in visual search tasks

What we have recently seen and attended to strongly influences how we subsequently allocate visual attention. A clear example is how repeated presentation of an object's features or location in visual search tasks facilitates subsequent detection or identification of that item, a phenomenon known as priming. Here, we review a large body of results from priming studies that suggest that a short-term implicit memory system guides our attention to recently viewed items. The nature of this memory system and the processing level at which visual priming occurs are still debated. Priming might be due to activity modulations of low-level areas coding simple stimulus characteristics or to higher level episodic memory representations of whole objects or visual scenes. Indeed, recent evidence indicates that only minor changes to the stimuli used in priming studies may alter the processing level at which priming occurs. We also review recent behavioral, neuropsychological, and neurophysiological evidence that indicates that the priming patterns are reflected in activity modulations at multiple sites along the visual pathways. We furthermore suggest that studies of priming in visual search may potentially shed important light on the nature of cortical visual representations. Our conclusion is that priming occurs at many different levels of the perceptual hierarchy, reflecting activity modulations ranging from lower to higher levels, depending on the stimulus, task, and context-in fact, the neural loci that are involved in the analysis of the stimuli for which priming effects are seen.

Semantic ambiguity resolution in positive schizotypy: A right hemisphere interpretation.

Positive schizotypal traits have been associated with right hemisphere activation. Previous research has indicated that the left and right hemispheres differ in their processing of semantic ambiguity; specifically, given sufficient time, the left hemisphere primes dominant meanings and inhibits subordinate meanings, and the right hemisphere primes both dominant and subordinate meanings. The authors examined whether individuals who differed in positive schizotypy demonstrated different patterns of priming on a semantic ambiguity task, reflective of differences in hemispheric activation. Individuals low in schizotypy demonstrated the expected pattern of priming the dominant meaning while inhibiting the subordinate meaning. Individuals high in schizotypy demonstrated similar priming of the dominant meaning but no inhibition of the subordinate meaning. The role of this failure of inhibition in the generation of schizotypal thought is discussed.

Does masked and unmasked priming reflect Bayesian inference as implemented in the Bayesian Reader?

Norris and Kinoshita (2008) describe a Bayesian theory of masked and unmasked priming designed to explain a complex pattern of word and nonword priming across a range of tasks. Their theory is implemented within the Bayesian Reader model, and the model makes some predictions that are confirmed in a set of experiments. The authors consider alternative accounts of priming and conclude that only their theory can account for the results obtained. However, contrary to the authors' claims, the Bayesian Reader makes a number of incorrect predictions regarding masked and unmasked priming phenomena, whereas alternative theories can accommodate current findings.

Neural Priming in Human Frontal Cortex: Multiple Forms of Learning Reduce Demands on the Prefrontal Executive System

Past experience is hypothesized to reduce computational demands in PFC by providing bottom-up predictive information that informs subsequent stimulus-action mapping. The present fMRI study measured cortical activity reductions ("neural priming"/"repetition suppression") during repeated stimulus classification to investigate the mechanisms through which learning from the past decreases demands on the prefrontal executive system. Manipulation of learning at three levels of representation-stimulus, decision, and response-revealed dissociable neural priming effects in distinct frontotemporal regions, supporting a multiprocess model of neural priming. Critically, three distinct patterns of neural priming were identified in lateral frontal cortex, indicating that frontal computational demands are reduced by three forms of learning: (a) cortical tuning of stimulus-specific representations, (b) retrieval of learned stimulus-decision mappings, and (c) retrieval of learned stimulus-response mappings. The topographic distribution of these neural priming effects suggests a rostrocaudal organization of executive function in lateral frontal cortex.

Priming of luminance-defined motion direction in visual search

Features that we have recently attended to strongly influence how we allocate visual attention across a subsequently viewed visual scene. Here, we investigate the characteristics of any such repetition effects during visual search for Gabor patch targets drifting in the odd direction relative to a set of distractors. The results indicate that repetition of motion direction has a strong effect upon subsequent allocation of attention. This was the case for judgments of a target's presence or absence, of a target's location, and of the color of a target drifting in the odd direction. Furthermore, distractor repetition on its own can facilitate search performance on subsequent trials, indicating that the benefits of repetition of motion direction are not confined to repetition of target features. We also show that motion direction need not be the target-defining dimension throughout a trial block for motion priming to occur, but that priming can build up with only one presentation of a given target direction, even within blocks of trials where the target may, unpredictably, be defined by a different feature (color, in this case), showing that dimensional-weighting accounts cannot, on their own, account for motion direction priming patterns. Finally, we show by randomizing the set size between trials that priming of motion direction can decrease search rates in visual search.

Priming of luminance-defined motion direction in visual search

Features that we have recently attended to strongly influence how we allocate visual attention across a subsequently viewed visual scene. Here, we investigate the characteristics of any such repetition effects during visual search for Gabor patch targets drifting in the odd direction relative to a set of distractors. The results indicate that repetition of motion direction has a strong effect upon subsequent allocation of attention. This was the case for judgments of a target’s presence or absence, of a target’s location, and of the color of a target drifting in the odd direction. Furthermore, distractor repetition on its own can facilitate search performance on subsequent trials, indicating that the benefits of repetition of motion direction are not confined to repetition of target features. We also show that motion direction need not be the target-defining dimension throughout a trial block for motion priming to occur, but that priming can build up with only one presentation of a given target direction, even within blocks of trials where the target may, unpredictably, be defined by a different feature (color, in this case), showing that dimensional-weighting accounts cannot, on their own, account for motion direction priming patterns. Finally, we show by randomizing the set size between trials that priming of motion direction can decrease search rates in visual search.

The Time Course of Verb Processing in Dutch Sentences

The verb has traditionally been characterized as the central element in a sentence. Nevertheless, the exact role of the verb during the actual ongoing comprehension of a sentence as it unfolds in time remains largely unknown. This paper reports the results of two Cross-Modal Lexical Priming (CMLP) experiments detailing the pattern of verb priming during on-line processing of Dutch sentences. Results are contrasted with data from a third CMLP experiment on priming of nouns in similar sentences. It is demonstrated that the meaning of a matrix verb remains active throughout the entire matrix clause, while this is not the case for the meaning of a subject head noun. Activation of the meaning of the verb only dissipates upon encountering a clear signal as to the start of a new clause.

Morphological priming by itself: A study of Portuguese conjugations

Does the language processing system make use of abstract grammatical categories and representations that are not directly visible from the surface form of a linguistic expression? This study examines stem-formation processes and conjugation classes, a case of ‘pure’ morphology that provides insight into the role of grammatical structure in language processing. We report results from a cross-modal priming experiment examining 1st and 3rd conjugation verb forms in Portuguese. Although items were closely matched with respect to a range of non-morphological factors, distinct priming patterns were found for 1st and 3rd conjugation stems. We attribute the observed priming patterns to different representations of conjugational stems, combinatorial morphologically structured ones for 1st conjugation and unanalyzed morphologically unstructured ones for 3rd conjugation stems. Our findings underline the importance of morphology for language comprehension indicating that morphological analysis goes beyond the identification of grammatical morphemes.

Seeing the world through another person’s eyes: Simulating selective attention via action observation

Selective attention is usually considered an egocentric mechanism, biasing sensory information based on its behavioural relevance to oneself. This study provides evidence for an equivalent allocentric mechanism that allows passive observers to selectively attend to information from the perspective of another person. In a negative priming task, participants reached for a red target stimulus whilst ignoring a green distractor. Distractors located close to their hand were inhibited strongly, consistent with an egocentric frame of reference. When participants took turns with another person, the pattern of negative priming shifted to an allocentric frame of reference: locations close to the hand of the observed agent (but far away from the participant’s hand) were inhibited strongly. This suggests that witnessing another’s action leads the observer to simulate the same selective attention mechanisms such that they effectively perceive their surroundings from the other person’s perspective.