‘Hyper-priming’ in thought-disordered schizophrenic patients

Moritz, Steffen; Mersmann, Kathrin; Kloss, Martin; Jacobsen, Dirk; Wilke, Uta; Andresen, Burghard; Naber, Dieter; Pawlik, Kurt

doi:10.1017/s0033291701003105

Cited by 87 publications

(66 citation statements)

References 30 publications

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“…Greater priming is thought to reflect greater activation of the target by the prime. Consistent with increased spread of activation to weak associates, an abnormally large priming effect for indirectly related words has been found in thought-disordered schizophrenia patients, although only when the prime-target interval (or stimulus-onset asynchrony (SOA)) is relatively short (≤300 ms) (Moritz et al, 2001;Moritz et al, 2003;Spitzer et al, 1993).…”

Section: Introductionmentioning

confidence: 74%

Electrophysiological insights into conceptual disorganization in schizophrenia

Kiang

Kutas

Light

et al. 2007

Schizophrenia Research

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Disorganized speech, or thought disorder, in schizophrenia may reflect abnormal processing of meaningful concepts. To examine whether schizophrenia involves abnormalities in how a meaningful context influences processing of concepts strongly, weakly, or not related to it, we used the N400, an event-related brain potential (ERP) index of semantic relatedness. ERPs were recorded from schizophrenia patients (n=18) and normal controls (n=18) while they viewed category definitions (e.g., a type of fruit), each followed by a target word that was either a hightypicality category exemplar (apple), low-typicality exemplar (cherry), or non-exemplar (clamp). Participants' task was to indicate via button-press whether or not the target belonged to the category. In both patients and controls, N400 amplitude was largest (most negative) for nonexemplars, intermediate for low-typicality exemplars, and smallest (least negative) for hightypicality exemplars. Compared to controls, patients showed a trend toward reduced N400 amplitude differences between non-exemplars and low-typicality exemplars. Most importantly, within patients, reduced N400 amplitude differences between high-and low-typicality exemplars were correlated with psychotic symptoms. In schizophrenia patients, an N400 index of semantic processing was associated with psychotic symptoms. Psychosis may be associated with greater similarity in how concepts strongly and weakly meaningfully related to their context are processed.

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Section: Introductionmentioning

confidence: 74%

Electrophysiological insights into conceptual disorganization in schizophrenia

Kiang

Kutas

Light

et al. 2007

Schizophrenia Research

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“…A contribution of controlled processes to the observed result is highly unlikely, since postlexical matching strategies are not thought to be involved in pronunciation tasks 5,45 and expectancy-based priming is unlikely to occur at such short SOAs. 5 Thus, this finding can be paralleled to observations of hyperpriming under automatic access conditions and for weak or indirect stimulus dimensions in patients with thought disorder, [9][10][11][18][19][20][21] rendering dopaminergic hyperactivity a plausible basis for priming abnormalities in patients with schizophrenia.…”

Section: Discussionmentioning

confidence: 68%

“…However, in patients with schizophrenia, hyperpriming ceases to exist at such "very short" SOAs, 18 possibly because of perceptual processing abnormalities. 9 Thus, although the investigation of healthy young participants under such "ideal" conditions might provide more accurate insights into the mechanisms governing priming, the generalizability of our findings to clinical populations should be confirmed in further studies.…”

Section: Limitationsmentioning

confidence: 78%

“…Several studies have reported increased single-word priming in patients with schizophrenia, especially those with formal thought disorder. [7][8][9][10][11][12] Although not always replicated, [13][14][15][16][17] this hyperpriming appears to be highly consistent under conditions favouring automatic processes 18 as well as for target words either indirectly (e.g., lemon-sweet) 10,[18][19][20] or weakly associated with the prime word. 21 Based on these observations, it has been suggested that automatic spreading of lexical activation is accelerated and/or travels abnormally large distances in thoughtdisordered patients with schizophrenia.…”

Section: Introductionmentioning

confidence: 89%

“…23 This excessive spread of activation has been hypothesized to constitute the cognitive correlate of positive formal thought disorder. 9,18,21 However, it is not clear how these findings relate to the dopaminergic dysfunction assumed to underlie schizophrenia. 24,25 Several studies showing a reduction of indirect semantic priming upon administration of levodopa (L-Dopa) or dopaminergic agonists in healthy individuals [26][27][28] have led to the suggestion that dopamine (DA) increases the signalto-noise ratio within the semantic network, resulting in a more focused activation pattern.…”

Section: Introductionmentioning

confidence: 99%

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Effects of dopaminergic modulation on automatic semantic priming: a double-blind study

Andreou

Veith

Bozikas

et al. 2014

J Psychiatry Neurosci

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IntroductionThe semantic priming effect refers to the observation that reaction times (i.e., pronunciation or speeded lexical decision) to a target word, such as "dog" are faster when the word is preceded by a related prime (e.g., "cat") than when it is preceded by an unrelated word (e.g., "pen").1,2 This effect is attributed to an automatic spreading of activation, initiated by the prime word, to adjacent nodes within the semantic network, 3,4 but also to controlled processes not related to the semantic store, such as attention-based expectancy (i.e., generation of predictions) and postlexical matching (i.e., evaluation of the semantic association between prime and target). 4,5 These processes can be differentially tapped by manipulating various aspects of priming paradigms, such as the primetarget interval (stimulus onset asynchrony [SOA]), the proportion of related word pairs or the nonword ratio in lexical decision designs. It is generally accepted that the contribution of controlled processes to priming becomes more pronounced with the increase of any of the aforementioned variables and is greater in lexical decision tasks than word pronunciation tasks. 5,6 Semantic priming tasks have been widely used in the schizophrenia literature. Several studies have reported increased single-word priming in patients with schizophrenia, especially those with formal thought disorder. Background: Enhanced automatic spreading of activation in the semantic network has been suggested to underlie formal thought disorder in patients with schizophrenia, but it is not clear how this relates to the dopaminergic dysfunction implicated in the disorder. Previous studies on dopaminergic modulation of priming in healthy volunteers have focused on controlled rather than automatic processes. The present study aimed to examine the effects of both a dopaminergic agonist and a dopaminergic antagonist on semantic priming while minimizing the contribution of controlled processes. Methods: We investigated the effects of levodopa (L-Dopa; 100 mg), haloperidol (2 mg) and placebo on priming in healthy participants within a randomized, double-blind, crossover design. We used a pronunciation priming task with word triplets; the middle word was an ambiguous word, whereas the first word of the triplet served to provide either a congruent, incongruent or unbiased context for the target word. Two stimulus onset asynchronies (SOA) were used: 150 ms and 750 ms. Results:The study involved 34 participants. At an SOA of 150 ms, L-Dopa accelerated responses to incongruent targets and subordinate targets of ambiguous words, whereas haloperidol was associated with faster responses in congruent contexts and dominant targets. At an SOA of 750 ms, haloperidol accelerated responses to subordinate targets. Limitations: Modulations in the relative magnitude of priming according to substance and condition rather than absolute priming were assessed. Conclusion: Effects of L-Dopa on automatic priming processes appear to be different than those on controlled processes....

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Increased Temporal and Prefrontal Activity in Response to Semantic Associations in Schizophrenia

Kuperberg

Deckersbach²,

Holt³

et al. 2007

Arch Gen Psychiatry

103

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Context: Loosening of associations has long been considered a core feature of schizophrenia, but its neural correlate remains poorly understood.Objective: To test the hypothesis that, in comparison with healthy control subjects, patients with schizophrenia show increased neural activity within inferior prefrontal and temporal cortices in response to directly and indirectly semantically related (relative to unrelated) words.Design: A functional neuroimaging study using a semantic priming paradigm.Setting: Lindemann Mental Health Center, Boston, Mass.Participants: Seventeen right-handed medicated outpatients with chronic schizophrenia and 15 healthy volunteers, matched for age and parental socioeconomic status.Interventions: Functional magnetic resonance imaging as participants viewed directly related, indirectly related, and unrelated word pairs and performed a lexical decision task.Main Outcome Measures: Event-related functional magnetic resonance imaging measures of blood oxygenation level−dependent activity (1) within a priori temporal and prefrontal anatomic regions of interest and (2) at all voxels across the cortex.Results: Patients and controls showed no behavioral differences in priming but opposite patterns of hemodynamic modulation in response to directly related (relative to unrelated) word pairs primarily within inferior prefrontal cortices, and to indirectly related (relative to unrelated) word pairs primarily within temporal cortices. Whereas controls showed the expected decreases in activity in response to semantic relationships (hemodynamic response suppression), patients showed inappropriate increases in response to semantic relationships (hemodynamic response enhancement) in many of the same regions. Moreover, hemodynamic response enhancement within the temporal fusiform cortices to indirectly related (relative to unrelated) word pairs predicted positive thought disorder. Conclusion:Medicated patients with chronic schizophrenia, particularly those with positive thought disorder, show inappropriate increases in activity within inferior prefrontal and temporal cortices in response to semantic associations.

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‘Hyper-priming’ in thought-disordered schizophrenic patients

Cited by 87 publications

References 30 publications

Electrophysiological insights into conceptual disorganization in schizophrenia

Electrophysiological insights into conceptual disorganization in schizophrenia

Effects of dopaminergic modulation on automatic semantic priming: a double-blind study

Increased Temporal and Prefrontal Activity in Response to Semantic Associations in Schizophrenia

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