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Electrophysiological studies in humans and animals suggest that noninvasive neurostimulation methods such as transcranial direct current stimulation (tDCS) can elicit long-lasting [1], polarity-dependent [2] changes in neocortical excitability. Application of tDCS can have significant and selective behavioral consequences that are associated with the(More)
Processing of speech is obligatory. Thus, during normal speech comprehension, the listener is aware of the overall meaning of the speaker's utterance without the need to direct attention to individual linguistic and paralinguistic (intonational, prosodic, etc.) features contained within the speech signal. However, most functional neuroimaging studies of(More)
An important and unresolved question is how the human brain processes speech for meaning after initial analyses in early auditory cortical regions. A variety of left-hemispheric areas have been identified that clearly support semantic processing, although a systematic analysis of directed interactions among these areas is lacking. We applied dynamic causal(More)
We investigated the relationship between cerebral activity (measured with positron emission tomography) and word rate in normal subjects and aphasic patients listening to monosyllabic words at rates up to those encountered in normal speech. By measuring the slope of the regression of the individual activity-word rate responses in the temporal cortex in(More)
Previous studies of patients with phonological and surface alexia have demonstrated a double dissociation between the reading of pseudo words and words with atypical spelling-to-sound relationships. A corresponding double dissociation in the neuronal activation patterns for pseudo words and exception words has not, however, been consistently demonstrated in(More)
Competing theories of short-term memory function make specific predictions about the functional anatomy of auditory short-term memory and its role in language comprehension. We analysed high-resolution structural magnetic resonance images from 210 stroke patients and employed a novel voxel based analysis to test the relationship between auditory short-term(More)
Although it is well established that thalamic lesions may lead to profound amnesia, the precise contribution of thalamic sub-regions to memory remains unclear. In an influential article Aggleton and Brown proposed that recognition memory depends on two processes supported by distinct thalamic and cortical structures. Familiarity is mediated by the(More)
We used a two stage procedure to predict which stroke patients would have chronic difficulties gesturing how to use an object when object recognition and hand movements were intact. First, we searched our PLORAS database by behavior and identified 5 patients who had chronic difficulty gesturing object use but no difficulty recognising objects, comprehending(More)
Focal brain lesions are assumed to produce language deficits by two basic mechanisms: local cortical dysfunction at the lesion site, and remote cortical dysfunction due to disruption of the transfer and integration of information between connected brain regions. However, functional imaging studies investigating language outcome after aphasic stroke have(More)
There have been many functional imaging studies that have investigated the neural correlates of speech perception by contrasting neural responses to speech and "speech-like" but unintelligible control stimuli. A potential drawback of this approach is that intelligibility is necessarily conflated with a change in the acoustic parameters of the stimuli. The(More)