Purpose: Diagnostic recommendations for acquired apraxia of speech (AOS) have been contradictory concerning whether speech sound errors are consistent or variable. Studies have reported divergent findings that, on face value, could argue either for or against error consistency as a diagnostic criterion. The purpose of this study was to explain…

Background: Knowledge of the discourse performance of non-brain-damaged individuals is critical not only for its differentiation from disordered expression but also for more accurate models of ageing and communication. The effect of ageing and cognitive skills on the cohesive adequacy of discourse has, until now, presented a confusing and…

Purpose: Individuals with primary progressive apraxia of speech (PPAOS) have apraxia of speech (AOS) in which disruptions in articulation or prosody predominate the speech pattern, referred to, respectively, as phonetic or prosodic subtypes. Many develop aphasia and/or dysarthria. Past research has demonstrated that simple temporal acoustic…

The neurocognitive impairments associated with restricted and repetitive behaviors (RRBs) in autism spectrum disorder (ASD) are not yet clear. Prior studies indicate that individuals with ASD show reduced cognitive flexibility, which could reflect difficulty shifting from a previously learned response pattern or a failure to maintain a new…

The study of homophones--words with different meanings that sound the same--has great potential to inform models of language production. Of particular relevance is a phenomenon termed "frequency" inheritance, where a low-frequency word (e.g., "deer") is produced more fluently than would be expected based on its frequency…

Executive function is best measured in loosely structured, multi-component tasks that reflect real-life demands. These tasks require participants to develop a strategy, keep a plan in mind and monitor time. Errors include ignoring stated goals ("goal neglect"), over-allocation of time to one task and violating rules. Teasing apart such…

Neglect dyslexia--a peripheral reading disorder generally associated with left spatial neglect--is characterized by omissions or substitutions of the initial letters of words. Several observations suggest that neglect dyslexia errors are independent of viewer-centered coordinates; the disorder is therefore thought to reflect impairment at the…

This study evaluates spelling errors in the three subtypes of primary progressive aphasia (PPA): agrammatic (PPA-G), logopenic (PPA-L), and semantic (PPA-S). Forty-one PPA patients and 36 age-matched healthy controls were administered a test of spelling. The total number of errors and types of errors in spelling to dictation of regular words,…

Semantic errors in aphasia (e.g., naming a horse as "dog") frequently arise from faulty mapping of concepts onto lexical items. A recent study by our group used voxel-based lesion-symptom mapping (VLSM) methods with 64 patients with chronic aphasia to identify voxels that carry an association with semantic errors. The strongest associations were…

Objective: The error-related negativity (ERN) is a negative deflection in the event-related potential after an incorrect response, which is often increased in patients with obsessive-compulsive disorder (OCD). However, the relation of the ERN to comorbid tic disorders has not been examined in patients with OCD. This study compared ERN amplitudes…

Behavioral and functional neuroimaging studies indicate deficits in verbal working memory (WM) and frontoparietal dysfunction in individuals with dyslexia. Additionally, structural brain abnormalities in dyslexics suggest a dysconnectivity of brain regions associated with phonological processing. However, little is known about the functional…

Studies of sentence comprehension deficits in Parkinson's disease (PD) patients suggest that language processing involves circuits connecting subcortical and cortical regions. Anatomically segregated neural circuits appear to support different cognitive and motor functions. To investigate which functions are implicated in PD comprehension…

In a previous study (Dronkers, 1996), stroke patients identified as having apraxia of speech (AOS), an articulatory disorder, were found to have damage to the left superior precentral gyrus of the insula (SPGI). The present study sought (1) to characterize the performance of patients with AOS on a classic motor speech evaluation, and (2) to…