An fMRI investigation of the effects of attempted naming on word retrieval in aphasia.

In healthy controls, picture naming performance can be facilitated by a single prior exposure to the same picture ("priming"). This priming phenomenon is utilized in the treatment of aphasia, which often includes repeated picture naming as part of a therapeutic task. The current study sought to determine whether single and/or multiple exposures facilitate subsequent naming in aphasia and whether such facilitatory effects act through normal priming mechanisms. A functional magnetic resonance imaging paradigm was employed to explore the beneficial effects of attempted naming in two individuals with aphasia and a control group. The timing and number of prior exposures was manipulated, with investigation of both short-term effects (single prior exposure over a period of minutes) and long-term effects (multiple presentations over a period of days). Following attempted naming, both short-term and long-term facilitated items showed improvement for controls, while only the long-term condition showed benefits at a behavioral level for the participants with aphasia. At a neural level, effects of long-term facilitation were noted in the left precuneus for one participant with aphasia, a result also identified for the equivalent contrast in controls. It appears that multiple attempts are required to improve naming performance in the presence of anomia and that for some individuals with aphasia the source of facilitation may be similar to unimpaired mechanisms engaged outside the language network.

I'm sitting here feeling aphasic! A study of recurrent perseverative errors elicited in unimpaired speakers.

In this study, the recurrent perseverative errors produced by 44 speakers without impairment were examined in picture naming and reading aloud tasks under a fast response deadline. The proportion of perseverative relative to non-perseverative errors was greater in picture naming, the more error-prone task, than in reading aloud. Additionally, although perseverative errors were less likely to be related to the target than non-perseverative errors, the overall distribution of perseverative and non-perseverative errors in each task was similar. It is concluded that the perseverative errors produced by the participants reflected both the degree and level at which language processing efficiency was reduced in each task. This is consistent with a more recent account of perseveration as a result of normally existing persistent activation overcoming weakened activation of a target at any level of language processing. These results are compared with recent studies of recurrent perseverative errors produced by people with aphasia in light of the cognitive neuropsychological assumption that speakers with and without impairment utilise a common language processing system.

Augmenting melodic intonation therapy with non-invasive brain stimulation to treat impaired left-hemisphere function: two case studies.

The purpose of this study was to investigate whether or not the right hemisphere can be engaged using Melodic Intonation Therapy (MIT) and excitatory repetitive transcranial magnetic stimulation (rTMS) to improve language function in people with aphasia. The two participants in this study (GOE and AMC) have chronic non-fluent aphasia. A functional Magnetic Resonance Imaging (fMRI) task was used to localize the right Broca's homolog area in the inferior frontal gyrus for rTMS coil placement. The treatment protocol included an rTMS phase, which consisted of 3 treatment sessions that used an excitatory stimulation method known as intermittent theta burst stimulation, and a sham-rTMS phase, which consisted of 3 treatment sessions that used a sham coil. Each treatment session was followed by 40 min of MIT. A linguistic battery was administered after each session. Our findings show that one participant, GOE, improved in verbal fluency and the repetition of phrases when treated with MIT in combination with TMS. However, AMC showed no evidence of behavioral benefit from this brief treatment trial. Post-treatment neural activity changes were observed for both participants in the left Broca's area and right Broca's homolog. These case studies indicate that a combination of MIT and rTMS applied to the right Broca's homolog has the potential to improve speech and language outcomes for at least some people with post-stroke aphasia.

Disentangling the web: neologistic perseverative errors in jargon aphasia.

This article explores the relationship between the neologisms and perseverative errors produced by KVH, a man with severe neologistic jargon aphasia. Detailed examination of KVH's level of language processing breakdown revealed mild difficulties with phonological encoding and severe difficulties accessing the lexical form of the word. Many of KVH's neologisms contained phonemes perseverated from previous neologisms, suggesting an integral relationship between the production of neologisms and the perseveration of phonemes. Furthermore, KVH's patterns of whole word (total)and phonological (blended) perseverations reflected his proposed underlying language processing deficits, consistent with recent literature on perseveration (e.g.,Cohen and Dehaene, 1998). However, the simple binary distinction oftotalandblendedperseveration is proposed to be somewhat limited for understanding the underlying nature of KVH's complex neologistic errors. Possible explanations regarding the mechanisms underlying the production of KVH's neologistic and perseverative errors also are discussed.