Research - Neurofunctional Imaging

PAPERS

Visual cortical inhibitory function in migraine is not generally impaired: evidence from a combined psychophysical test with an fMRI study *

Reduction in V1 Activation Associated with Decreased Visibility of a Visual Target - Abstract *

Visual stress theory and its application to reading and reading tests *

Asymmetry of Subinsular Anisotropy by in vivo Diffusion Tensor Imaging *

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Visual Distortion Provoked by a Stimulus in Migraine Associated With Hyperneuronal Activity

An ER-fMRI investigation of morphological inflection in German reveals that the brain makes a distinction between regular and irregular forms

The brain is not single-minded about inflectional morphology: A response to the commentaries

COMPARING CORTICAL ACTIVATIONS FOR SILENT AND OVERT SPEECH USING EVENT-RELATED fMRI

At present, functional magnetic resonance imaging (fMRI) of cortical language functions favors silent task paradigms with no overt speaking, due to severe motion artifacts in MR images induced by vocalization. To the extent that the neural substrate of silent speaking might differ from that of overt speaking, this is a problem for understanding spoken language. The present study combined event related fMRI methodology with a set of techniques for motion reduction, detection, and correction to further investigate overt speech and compare it to silent speech. The purpose of the study was two-fold. We aimed to test a multiple-step image processing protocol involving discrimination and separation of motion-induced signals from activation-induced signals and we aimed to use this multi-step image processing protocol to compare the similarity of activation of cortical pathways potentially relevant to language production during silent and overt speech, focusing on Broca area and primary motor cortex as test cases. If the problem of motion artifact can be handled effectively, fMRI can add greatly to the tools available to investigate human language. Hum. Brain Mapping 15:39-53, 2001. © 2001 Wiley-Liss, Inc.

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PRESENTATIONS

DIVISION OF COMPUTATIONAL LABOR BETWEEN BROCA'S AREA AND WERNICKE'S AREA IN READING VISUALLY PRESENTED WORDS

Considerable effort has been devoted to identifying the neural substrate of word reading, and in particular how the brain represents and coordinates rule-governed spelling-to-pronunciation translation based on something like “phonics” versus associative translation based on retrieval from lexical memory. (continued)

ASYMMETRY OF SUBINSULAR ANISOTROPY BY IN VIVO DIFFUSION TENSOR IMAGING

A cortical asymmetry has been described in human auditory cortex (the planum temporal) and Wernicke’s area. The asymmetry of the Wernicke’s area mainly concerns the size of the cortex, usually larger in the left side that specializes in speech and language, implying an association of the cortical asymmetry with the hemispheric functional lateralization.
(continued)

ATTENTION - EVOKED ACTIVATION IN THE VISUAL CORTEX

A recent study demonstrated that visual attention, without presentation of a stimulus, evoked a response in the early visual cortex (V1, V2, and V3), and the attention-related activity strongly depended upon the difficulty of tasks [1]. In this study, we investigate contributions of visual attention and pattern stimulation to measured BOLD responses in the visual cortex during ultra-short visual stimulation.  (continued)

AN fMRI STUDY OF REGULAR AND IRREGULAR INFLECTION IN GERMAN

Symbol-manipulating and associative accounts of the nature of cognitive processing have both focused on inflectional morphology. These conflicting accounts are in general agreement that irregular inflection is accomplished by associative memory. The conflict arises with regard to regular inflection.  (continued)

PATTERN-INDUCED VISUAL STRESS AND CORTICAL ACTIVATION IN MIGRAINE PATIENTS

Migraine affects nearly 12% of the population in the United States. People suffering from migraine (migraineurs) are highly susceptible to visual discomfort and distortion. During migraine attacks, photophobia is one of the most common complaints. Between migraine attacks, migraineurs are also sensitive to bright light and certain visual patterns. For example, migraineurs frequently report illusions of color, shape, and motion while viewing a black-and-white stripe pattern. In this preliminary study, we investigate visual neuronal activity and its association with self-described visual distortion and discomfort in migraineurs.  (continued)

USING fMRI TO COMPARE TALKING ALOUD TO "THE LITTLE VOICE IN THE HEAD"

Vocalization-induced motion artifact has limited the ability to apply fMRI to speech production. We describe a set of techniques for motion reduction, detection, and correction intended to remove these artifacts from cortical activation during overt speech. We combined these techniques with Event-Related fMRI to compare overt speech with silent speech, focusing on Broca’s area and its right-hemisphere homologue plus two inferior regions of left and right primary motor cortex as regions of interest.  (continued)