201
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Binder JR, Desai RH. The neurobiology of semantic memory. Trends Cogn Sci 2011; 15:527-36. [PMID: 22001867 PMCID: PMC3350748 DOI: 10.1016/j.tics.2011.10.001] [Citation(s) in RCA: 1102] [Impact Index Per Article: 84.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/05/2011] [Accepted: 10/06/2011] [Indexed: 11/17/2022]
Abstract
Semantic memory includes all acquired knowledge about the world and is the basis for nearly all human activity, yet its neurobiological foundation is only now becoming clear. Recent neuroimaging studies demonstrate two striking results: the participation of modality-specific sensory, motor, and emotion systems in language comprehension, and the existence of large brain regions that participate in comprehension tasks but are not modality-specific. These latter regions, which include the inferior parietal lobe and much of the temporal lobe, lie at convergences of multiple perceptual processing streams. These convergences enable increasingly abstract, supramodal representations of perceptual experience that support a variety of conceptual functions including object recognition, social cognition, language, and the remarkable human capacity to remember the past and imagine the future.
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Affiliation(s)
- Jeffrey R Binder
- Department of Neurology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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202
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Purcell JJ, Turkeltaub PE, Eden GF, Rapp B. Examining the central and peripheral processes of written word production through meta-analysis. Front Psychol 2011; 2:239. [PMID: 22013427 PMCID: PMC3190188 DOI: 10.3389/fpsyg.2011.00239] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 09/01/2011] [Indexed: 11/24/2022] Open
Abstract
Producing written words requires “central” cognitive processes (such as orthographic long-term and working memory) as well as more peripheral processes responsible for generating the motor actions needed for producing written words in a variety of formats (handwriting, typing, etc.). In recent years, various functional neuroimaging studies have examined the neural substrates underlying the central and peripheral processes of written word production. This study provides the first quantitative meta-analysis of these studies by applying activation likelihood estimation (ALE) methods (Turkeltaub et al., 2002). For alphabet languages, we identified 11 studies (with a total of 17 experimental contrasts) that had been designed to isolate central and/or peripheral processes of word spelling (total number of participants = 146). Three ALE meta-analyses were carried out. One involved the complete set of 17 contrasts; two others were applied to subsets of contrasts to distinguish the neural substrates of central from peripheral processes. These analyses identified a network of brain regions reliably associated with the central and peripheral processes of word spelling. Among the many significant results, is the finding that the regions with the greatest correspondence across studies were in the left inferior temporal/fusiform gyri and left inferior frontal gyrus. Furthermore, although the angular gyrus (AG) has traditionally been identified as a key site within the written word production network, none of the meta-analyses found it to be a consistent site of activation, identifying instead a region just superior/medial to the left AG in the left posterior intraparietal sulcus. These meta-analyses and the discussion of results provide a valuable foundation upon which future studies that examine the neural basis of written word production can build.
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Affiliation(s)
- Jeremy J Purcell
- Department of Pediatrics, Center for the Study of Learning, Georgetown University Washington, DC, USA
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203
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Fisher JE, Cortes CR, Griego JA, Tagamets MA. Repetition of letter strings leads to activation of and connectivity with word-related regions. Neuroimage 2011; 59:2839-49. [PMID: 21982931 DOI: 10.1016/j.neuroimage.2011.09.047] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 09/14/2011] [Accepted: 09/20/2011] [Indexed: 10/17/2022] Open
Abstract
Individuals learn to read by gradually recognizing repeated letter combinations. However, it is unclear how or when neural mechanisms associated with repetition of basic stimuli (i.e., strings of letters) shift to involvement of higher-order language networks. The present study investigated this question by repeatedly presenting unfamiliar letter strings in a one-back matching task during an hour-long period. Activation patterns indicated that only brain areas associated with visual processing were activated during the early period, but additional regions that are usually associated with semantic and phonological processing in inferior frontal gyrus were recruited after stimuli became more familiar. Changes in activation were also observed in bilateral superior temporal cortex, also suggestive of a shift toward a more language-based processing strategy. Connectivity analyses reveal two distinct networks that correspond to phonological and visual processing, which may reflect the indirect and direct routes of reading. The phonological route maintained a similar degree of connectivity throughout the experiment, whereas visual areas increased connectivity with language areas as stimuli became more familiar, suggesting early recruitment of the direct route. This study provides insight about plasticity of the brain as individuals become familiar with unfamiliar combinations of letters (i.e., words in a new language, new acronyms) and has implications for engaging these linguistic networks during development of language remediation therapies.
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Affiliation(s)
- Joscelyn E Fisher
- Maryland Psychiatric Research Center, University of Maryland Baltimore, P.O. Box 21247, Baltimore, MD 21228, USA
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204
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Savill NJ, Thierry G. Electrophysiological evidence for impaired attentional engagement with phonologically acceptable misspellings in developmental dyslexia. Front Psychol 2011; 2:139. [PMID: 21734903 PMCID: PMC3124829 DOI: 10.3389/fpsyg.2011.00139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 06/09/2011] [Indexed: 11/13/2022] Open
Abstract
Event-related potential (ERP) studies of word recognition have provided fundamental insights into the time-course and stages of visual and auditory word form processing in reading. Here, we used ERPs to track the time-course of phonological processing in dyslexic adults and matched controls. Participants engaged in semantic judgments of visually presented high-cloze probability sentences ending either with (a) their best completion word, (b) a homophone of the best completion, (c) a pseudohomophone of the best completion, or (d) an unrelated word, to examine the interplay of phonological and orthographic processing in reading and the stage(s) of processing affected in developmental dyslexia. Early ERP peaks (N1, P2, N2) were modulated in amplitude similarly in the two groups of participants. However, dyslexic readers failed to show the P3a modulation seen in control participants for unexpected homophones and pseudohomophones (i.e., sentence completions that are acceptable phonologically but are misspelt). Furthermore, P3a amplitudes significantly correlated with reaction times in each experimental condition. Our results showed no sign of a deficit in accessing phonological representations during reading, since sentence primes yielded phonological priming effects that did not differ between participant groups in the early phases of processing. On the other hand, we report new evidence for a deficient attentional engagement with orthographically unexpected but phonologically expected words in dyslexia, irrespective of task focus on orthography or phonology. In our view, this result is consistent with deficiency in reading occurring from the point at which attention is oriented to phonological analysis, which may underlie broader difficulties in sublexical decoding.
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Affiliation(s)
| | - Guillaume Thierry
- School of Psychology, Bangor UniversityBangor, UK
- Economic and Social Research Council Centre for Research on Bilingualism in Theory and Practice, Bangor UniversityBangor, UK
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205
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Vogel AC, Miezin FM, Petersen SE, Schlaggar BL. The putative visual word form area is functionally connected to the dorsal attention network. Cereb Cortex 2011; 22:537-49. [PMID: 21690259 DOI: 10.1093/cercor/bhr100] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The putative visual word form area (pVWFA) is the most consistently activated region in single word reading studies (i.e., Vigneau et al. 2006), yet its function remains a matter of debate. The pVWFA may be predominantly used in reading or it could be a more general visual processor used in reading but also in other visual tasks. Here, resting-state functional connectivity magnetic resonance imaging (rs-fcMRI) is used to characterize the functional relationships of the pVWFA to help adjudicate between these possibilities. rs-fcMRI defines relationships based on correlations in slow fluctuations of blood oxygen level-dependent activity occurring at rest. In this study, rs-fcMRI correlations show little relationship between the pVWFA and reading-related regions but a strong relationship between the pVWFA and dorsal attention regions thought to be related to spatial and feature attention. The rs-fcMRI correlations between the pVWFA and regions of the dorsal attention network increase with age and reading skill, while the correlations between the pVWFA and reading-related regions do not. These results argue the pVWFA is not used predominantly in reading but is a more general visual processor used in other visual tasks, as well as reading.
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Affiliation(s)
- Alecia C Vogel
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA.
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206
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Church JA, Balota DA, Petersen SE, Schlaggar BL. Manipulation of length and lexicality localizes the functional neuroanatomy of phonological processing in adult readers. J Cogn Neurosci 2011; 23:1475-93. [PMID: 20433237 PMCID: PMC2991592 DOI: 10.1162/jocn.2010.21515] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
In a previous study of single word reading, regions in the left supramarginal gyrus and left angular gyrus showed positive BOLD activity in children but significantly less activity in adults for high-frequency words [Church, J. A., Coalson, R. S., Lugar, H. M., Petersen, S. E., & Schlaggar, B. L. A developmental fMRI study of reading and repetition reveals changes in phonological and visual mechanisms over age. Cerebral Cortex, 18, 2054-2065, 2008]. This developmental decrease may reflect decreased reliance on phonological processing for familiar stimuli in adults. Therefore, in the present study, variables thought to influence phonological demand (string length and lexicality) were manipulated. Length and lexicality effects in the brain were explored using both ROI and whole-brain approaches. In the ROI analysis, the supramarginal and angular regions from the previous study were applied to this study. The supramarginal region showed a significant positive effect of length, consistent with a role in phonological processing, whereas the angular region showed only negative deflections from baseline with a strong effect of lexicality and other weaker effects. At the whole-brain level, varying effects of length and lexicality and their interactions were observed in 85 regions throughout the brain. The application of hierarchical clustering analysis to the BOLD time course data derived from these regions revealed seven clusters, with potentially revealing anatomical locations. Of note, a left angular gyrus region was the sole constituent of one cluster. Taken together, these findings in adult readers (1) provide support for a widespread set of brain regions affected by lexical variables, (2) corroborate a role for phonological processing in the left supramarginal gyrus, and (3) do not support a strong role for phonological processing in the left angular gyrus.
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Affiliation(s)
- Jessica A Church
- Department ofNeurology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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207
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Price CJ, Devlin JT. The interactive account of ventral occipitotemporal contributions to reading. Trends Cogn Sci 2011; 15:246-53. [PMID: 21549634 PMCID: PMC3223525 DOI: 10.1016/j.tics.2011.04.001] [Citation(s) in RCA: 448] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 04/04/2011] [Accepted: 04/05/2011] [Indexed: 11/16/2022]
Abstract
The ventral occipitotemporal cortex (vOT) is involved in the perception of visually presented objects and written words. The Interactive Account of vOT function is based on the premise that perception involves the synthesis of bottom-up sensory input with top-down predictions that are generated automatically from prior experience. We propose that vOT integrates visuospatial features abstracted from sensory inputs with higher level associations such as speech sounds, actions and meanings. In this context, specialization for orthography emerges from regional interactions without assuming that vOT is selectively tuned to orthographic features. We discuss how the Interactive Account explains left vOT responses during normal reading and developmental dyslexia; and how it accounts for the behavioural consequences of left vOT damage.
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Affiliation(s)
- Cathy J. Price
- Wellcome Trust Centre for Neuro-imaging, University College London, London WC1N 3BG, UK
| | - Joseph T. Devlin
- Cognitive, Perceptual and Brain Sciences, Division of Psychology and Language Sciences, University of London, London WC1E 6BT, UK
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208
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Price CJ, Devlin JT. The interactive account of ventral occipitotemporal contributions to reading. Trends Cogn Sci 2011. [PMID: 21549634 DOI: 10.1016/j.tics.2011.04.001.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ventral occipitotemporal cortex (vOT) is involved in the perception of visually presented objects and written words. The Interactive Account of vOT function is based on the premise that perception involves the synthesis of bottom-up sensory input with top-down predictions that are generated automatically from prior experience. We propose that vOT integrates visuospatial features abstracted from sensory inputs with higher level associations such as speech sounds, actions and meanings. In this context, specialization for orthography emerges from regional interactions without assuming that vOT is selectively tuned to orthographic features. We discuss how the Interactive Account explains left vOT responses during normal reading and developmental dyslexia; and how it accounts for the behavioural consequences of left vOT damage.
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Affiliation(s)
- Cathy J Price
- Wellcome Trust Centre for Neuro-imaging, University College London, London WC1N 3BG, UK
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209
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Wu HC, Nagasawa T, Brown EC, Juhasz C, Rothermel R, Hoechstetter K, Shah A, Mittal S, Fuerst D, Sood S, Asano E. γ-oscillations modulated by picture naming and word reading: intracranial recording in epileptic patients. Clin Neurophysiol 2011; 122:1929-42. [PMID: 21498109 DOI: 10.1016/j.clinph.2011.03.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 01/14/2011] [Accepted: 03/11/2011] [Indexed: 11/30/2022]
Abstract
OBJECTIVE We measured cortical gamma-oscillations in response to visual-language tasks consisting of picture naming and word reading in an effort to better understand human visual-language pathways. METHODS We studied six patients with focal epilepsy who underwent extraoperative electrocorticography (ECoG) recording. Patients were asked to overtly name images presented sequentially in the picture naming task and to overtly read written words in the reading task. RESULTS Both tasks commonly elicited gamma-augmentation (maximally at 80-100 Hz) on ECoG in the occipital, inferior-occipital-temporal and inferior-Rolandic areas, bilaterally. Picture naming, compared to reading task, elicited greater gamma-augmentation in portions of pre-motor areas as well as occipital and inferior-occipital-temporal areas, bilaterally. In contrast, word reading elicited greater gamma-augmentation in portions of bilateral occipital, left occipital-temporal and left superior-posterior-parietal areas. Gamma-attenuation was elicited by both tasks in portions of posterior cingulate and ventral premotor-prefrontal areas bilaterally. The number of letters in a presented word was positively correlated to the degree of gamma-augmentation in the medial occipital areas. CONCLUSIONS Gamma-augmentation measured on ECoG identified cortical areas commonly and differentially involved in picture naming and reading tasks. Longer words may activate the primary visual cortex for the more peripheral field. SIGNIFICANCE The present study increases our understanding of the visual-language pathways.
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Affiliation(s)
- Helen C Wu
- MD-PhD Program, Wayne State University, School of Medicine, Detroit, MI 48201, USA
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210
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Pegado F, Nakamura K, Cohen L, Dehaene S. Breaking the symmetry: Mirror discrimination for single letters but not for pictures in the Visual Word Form Area. Neuroimage 2011; 55:742-9. [PMID: 21111052 DOI: 10.1016/j.neuroimage.2010.11.043] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 10/23/2010] [Accepted: 11/12/2010] [Indexed: 11/15/2022] Open
Affiliation(s)
- Felipe Pegado
- INSERM, U992, Cognitive Neuroimaging Unit, Gif/Yvette, France.
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211
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Affiliation(s)
- Raymond A. Mar
- Department of Psychology, York University, Toronto M3J 1P3 Canada;
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212
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Graves WW, Binder JR, Desai RH, Conant LL, Seidenberg MS. Neural correlates of implicit and explicit combinatorial semantic processing. Neuroimage 2010; 53:638-46. [PMID: 20600969 PMCID: PMC2930088 DOI: 10.1016/j.neuroimage.2010.06.055] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 06/15/2010] [Accepted: 06/19/2010] [Indexed: 11/27/2022] Open
Abstract
Language consists of sequences of words, but comprehending phrases involves more than concatenating meanings: A boat house is a shelter for boats, whereas a summer house is a house used during summer, and a ghost house is typically uninhabited. Little is known about the brain bases of combinatorial semantic processes. We performed two fMRI experiments using familiar, highly meaningful phrases (lake house) and unfamiliar phrases with minimal meaning created by reversing the word order of the familiar items (house lake). The first experiment used a 1-back matching task to assess implicit semantic processing, and the second used a classification task to engage explicit semantic processing. These conditions required processing of the same words, but with more effective combinatorial processing in the meaningful condition. The contrast of meaningful versus reversed phrases revealed activation primarily during the classification task, to a greater extent in the right hemisphere, including right angular gyrus, dorsomedial prefrontal cortex, and bilateral posterior cingulate/precuneus, areas previously implicated in semantic processing. Positive correlations of fMRI signal with lexical (word-level) frequency occurred exclusively with the 1-back task and to a greater spatial extent on the left, including left posterior middle temporal gyrus and bilateral parahippocampus. These results reveal strong effects of task demands on engagement of lexical versus combinatorial processing and suggest a hemispheric dissociation between these levels of semantic representation.
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Affiliation(s)
- William W Graves
- Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, USA.
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213
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Fernández-Espejo D, Junque C, Cruse D, Bernabeu M, Roig-Rovira T, Fábregas N, Rivas E, Mercader JM. Combination of diffusion tensor and functional magnetic resonance imaging during recovery from the vegetative state. BMC Neurol 2010; 10:77. [PMID: 20815871 PMCID: PMC2941677 DOI: 10.1186/1471-2377-10-77] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Accepted: 09/03/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The rate of recovery from the vegetative state (VS) is low. Currently, little is known of the mechanisms and cerebral changes that accompany those relatively rare cases of good recovery. Here, we combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to study the evolution of one VS patient at one month post-ictus and again twelve months later when he had recovered consciousness. METHODS fMRI was used to investigate cortical responses to passive language stimulation as well as task-induced deactivations related to the default-mode network. DTI was used to assess the integrity of the global white matter and the arcuate fasciculus. We also performed a neuropsychological assessment at the time of the second MRI examination in order to characterize the profile of cognitive deficits. RESULTS fMRI analysis revealed anatomically appropriate activation to speech in both the first and the second scans but a reduced pattern of task-induced deactivations in the first scan. In the second scan, following the recovery of consciousness, this pattern became more similar to that classically described for the default-mode network. DTI analysis revealed relative preservation of the arcuate fasciculus and of the global normal-appearing white matter at both time points. The neuropsychological assessment revealed recovery of receptive linguistic functioning by 12-months post-ictus. CONCLUSIONS These results suggest that the combination of different structural and functional imaging modalities may provide a powerful means for assessing the mechanisms involved in the recovery from the VS.
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214
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Hinojosa JA, Méndez-Bértolo C, Carretié L, Pozo MA. Emotion modulates language production during covert picture naming. Neuropsychologia 2010; 48:1725-34. [PMID: 20188114 DOI: 10.1016/j.neuropsychologia.2010.02.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 01/19/2010] [Accepted: 02/17/2010] [Indexed: 11/28/2022]
Abstract
Previous studies have shown that emotional content modulates the activity of several components of the event-related potentials during word comprehension. However, little is known about the impact of affective information on the different processing stages involved in word production. In the present study we aimed to investigate the influence of positive and negative emotions in phonological encoding, a process that have been shown to take place between 300 and 450 ms in previous studies. Participants performed letter searching in a picture naming task. It was found that grapheme monitoring in positive and negative picture names was associated with slower reaction times and enhanced amplitudes of a positive component around 400 ms as compared to monitoring letters in neutral picture names. We propose that this modulation reflects a disruption in phonological encoding processes as a consequence of the capture of attention by affective content. Grapheme monitoring in positive picture names also elicited higher amplitudes than letter searching in neutral image names in a positive component around 100 ms. This amplitude enhancement might be interpreted as a manifestation of the 'positive offset' during conceptual preparation processes. The results of a control experiment with a passive viewing task showed that both effects cannot be simply attributed to the processing of the emotional images per se. Overall, it seems that emotion modulates word production at several processing stages.
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Affiliation(s)
- José A Hinojosa
- Instituto Pluridisciplinar, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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