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Event-related Functional Magnetic Resonance Imaging (event-related + functional_magnetic_resonance_imaging)
Selected AbstractsIMAGING STUDY: Exposure to smoking cues during an emotion recognition task can modulate limbic fMRI activation in cigarette smokersADDICTION BIOLOGY, Issue 4 2009Eric Artiges ABSTRACT Smoking cues (SCs) refer to smoking-associated environmental stimuli that may trigger craving and withdrawal symptoms, and predispose to relapse in smokers. Although previous brain imaging studies have explored neural responses to SCs, no study has characterized the effects of SCs on cerebral activity in smokers engaged in an attention-demanding cognitive task that is unrelated to smoking. Thirteen tobacco smokers and a demographically matched group of 13 healthy non-smokers participated in a fast event-related functional magnetic resonance imaging (fMRI) study that involved a visual task integrating SCs and neutral cues (NCs) during emotion recognition trials requiring a high level of attention. No significant SC-induced alterations were detected in smokers' behavioural performance. fMRI results show that non-smokers exhibited no difference between SC and NC trials; in contrast, smokers showed SC-induced widespread deactivations in a limbic, paralimbic and striatal network classically involved in addiction, and activation in the right dorsolateral prefrontal cortex. In addition, a correlation between deactivation of the right insula and the severity of smoking dependence (Fagerström test) was detected in smokers. These results suggest that the neural reactivity of smokers to SCs can be modified in the context of a cognitive challenge. This could reflect smokers' ability to inhibit cue-induced craving and may help in smoking cessation. [source] Auditory orienting and inhibition of return in mild traumatic brain injury: A FMRI studyHUMAN BRAIN MAPPING, Issue 12 2009Andrew R. Mayer Abstract The semiacute phase of mild traumatic brain injury (mTBI) is associated with deficits in the cognitive domains of attention, memory, and executive function, which previous work suggests may be related to a specific deficit in disengaging attentional focus. However, to date, there have only been a few studies that have employed dynamic imaging techniques to investigate the potential neurological basis of these cognitive deficits during the semiacute stage of injury. Therefore, event-related functional magnetic resonance imaging was used to investigate the neurological correlates of attentional dysfunction in a clinically homogeneous sample of 16 patients with mTBI during the semiacute phase of injury (<3 weeks). Behaviorally, patients with mTBI exhibited deficits in disengaging and reorienting auditory attention following invalid cues as well as a failure to inhibit attentional allocation to a cued spatial location compared to a group of matched controls. Accordingly, patients with mTBI also exhibited hypoactivation within thalamus, striatum, midbrain nuclei, and cerebellum across all trials as well as hypoactivation in the right posterior parietal cortex, presupplementary motor area, bilateral frontal eye fields, and right ventrolateral prefrontal cortex during attentional disengagement. Finally, the hemodynamic response within several regions of the attentional network predicted response times better for controls than for patients with mTBI. These objective neurological findings represent a potential biomarker for the behavioral deficits in spatial attention that characterize the initial recovery phase of mTBI. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source] Differential activity in left inferior frontal gyrus for pseudowords and real words: An event-related fMRI study on auditory lexical decisionHUMAN BRAIN MAPPING, Issue 2 2005Zhuangwei Xiao Abstract After Newman and Twieg ([2001]: Hum Brain Mapp 14:39,47) and others, we used a fast event-related functional magnetic resonance imaging (fMRI) design and contrasted the lexical processing of pseudowords and real words. Participants carried out an auditory lexical decision task on a list of randomly intermixed real and pseudo Chinese two-character (or two-syllable) words. The pseudowords were constructed by recombining constituent characters of the real words to control for sublexical code properties. Processing of pseudowords and real words activated a highly comparable network of brain regions, including bilateral inferior frontal gyrus, superior, middle temporal gyrus, calcarine and lingual gyrus, and left supramarginal gyrus. Mirroring a behavioral lexical effect, left inferior frontal gyrus (IFG) was significantly more activated for pseudowords than for real words. This result disconfirms a popular view that this area plays a role in grapheme-to-phoneme conversion, as such a conversion process was unnecessary in our task with auditory stimulus presentation. An alternative view was supported that attributes increased activity in left IFG for pseudowords to general processes in decision making, specifically in making positive versus negative responses. Activation in left supramarginal gyrus was of a much larger volume for real words than for pseudowords, suggesting a role of this region in the representation of phonological or semantic information for two-character Chinese words at the lexical level. Hum Brain Mapp 25:212,221, 2005. © 2005 Wiley-Liss, Inc. [source] Cross-modal temporal order memory for auditory digits and visual locations: An fMRI studyHUMAN BRAIN MAPPING, Issue 4 2004Daren Zhang Abstract A function of working memory is to remember the temporal sequence of events, often occurring across different sensory modalities. To study the neural correlates of this function, we conducted an event-related functional magnetic resonance imaging (fMRI) experiment with a cross-modal memory task. Subjects were required to recall auditory digits and visual locations either in mixed order (cross-modality) or in separate order (within-modality). To identify the brain regions involved in the memory of cross-modal temporal order, we compared the blood oxygenation level-dependent (BOLD) response between the mixed and the separate order tasks. As a control, cortical areas sensitive to the memory load were mapped by comparing the 10-item condition with the 6-item condition in the separate order task. Results show that the bilateral prefrontal, right premotor, temporo-parietal junction (TPJ) and left superior parietal cortices had significantly more activation in the mixed task than in the separate task. Some of these areas were also sensitive to the memory load, whereas the right prefrontal cortex and TPJ were relatively more sensitive to the cross-modal order but not the memory load. Our study provides potential neural correlates for the episodic buffer, a key component of working memory as proposed previously [Baddeley. Trends Cogn Sci 2000;4:417,423]. Hum. Brain Mapping 22:280,289, 2004. © 2004 Wiley-Liss, Inc. [source] | ||||||||||