title: Spatio-temporal processing of words and nonwords: hemispheric laterality and acute alcohol intoxication.
abstract: This study examined neurofunctional correlates of reading by modulating semantic, lexical, and orthographic attributes of letter strings. It compared the spatio-temporal activity patterns elicited by real words (RW), pseudowords, orthographically regular, pronounceable nonwords (PN) that carry no meaning, and orthographically illegal, nonpronounceable nonwords (NN). A double-duty lexical decision paradigm instructed participants to detect RW while ignoring nonwords and to additionally respond to words that refer to animals (AW). Healthy social drinkers (N=22) participated in both alcohol (0.6 g/kg ethanol for men, 0.55 g/kg for women) and placebo conditions in a counterbalanced design. Whole-head MEG signals were analyzed with an anatomically-constrained MEG method. Simultaneously acquired ERPs confirm previous evidence. Spatio-temporal MEG estimates to RW and PN are consistent with the highly replicable left-lateralized ventral visual processing stream. However, the PN elicit weaker activity than other stimuli starting at ~230 ms and extending to the M400 (magnetic equivalent of N400) in the left lateral temporal area, indicating their reduced access to lexicosemantic stores. In contrast, the NN uniquely engage the right hemisphere during the M400. Increased demands on lexicosemantic access imposed by AW result in greater activity in the left temporal cortex starting at ~230 ms and persisting through the M400 and response preparation stages. Alcohol intoxication strongly attenuates early visual responses occipito-temporally overall. Subsequently, alcohol selectively affects the left prefrontal cortex as a function of orthographic and semantic dimensions, suggesting that it modulates the dynamics of the lexicosemantic processing in a top-down manner, by increasing difficulty of semantic retrieval.
authors.affiliation: Department of Radiology, University of California, San Diego, 9500 Gilman Dr., 0841, La Jolla, CA 92093-0841, USA; Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: xenia@ucsd.edu.
authors.forename: Ksenija
authors.initials: K
authors.lastname: Marinkovic
authors.affiliation: Department of Radiology, University of California, San Diego, 9500 Gilman Dr., 0841, La Jolla, CA 92093-0841, USA.
authors.forename: Burke Q
authors.initials: BQ
authors.lastname: Rosen
authors.affiliation: Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Brendan
authors.initials: B
authors.lastname: Cox
authors.affiliation: Department of Radiology, University of California, San Diego, 9500 Gilman Dr., 0841, La Jolla, CA 92093-0841, USA.
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Hagler
mesh_terms: D000328:Adult; D000435:Alcoholic Intoxication / Q000473:pathology*; D001931:Brain Mapping; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011578:Psycholinguistics; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D012660:Semantics; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Anatomically-constrained MEG; ERP; Lexical decision; N400; Pseudoword; Reading