Recent reports suggest that speech perception deficits, typical in aphasia, can be remediated by behavioral training. The nature of this effect and its physiological basis are unclear. One possible mechanism relates to enhancement of auditory attention and working memory related to speech and language processing, which in turn facilitates cerebral re-organization of damaged neural networks. Attention and working memory are often impaired in people with aphasia. Past studies have demonstrated improved auditory processing using behavioral treatments that enhance attention and perceptual learning. The interpretation of the improvements reported in these studies is confounded by limitations in theory, design, and methodology.; The study was conducted in two parts. The first experiment retrospectively analyzed data from 11 participants with aphasia that had been in a double-blind, placebo controlled, event-related potential (ERP) drug study of auditory attention deficits conducted by Gerry Stefanatos, D.Phil. These data were used to answer several questions regarding the effects of amphetamines on auditory attention deficits and cerebral plasticity in people with aphasia. The second experiment was an exploratory singleparticipant study that evaluated the effects an experimental behavioral therapy on auditory attention, working memory, and speech perception in a participant with aphasia. The effects of treatment were compared against a neurologically intact control subject after undergoing the same treatment procedures. Utilizing an ABA design, the second experiment compared the effect of reinforcement learning on three auditory working memory span tasks (complex tones, consonant-vowels, and consonant-vowel-consonants). This clinical experiment tested the hypothesis that auditory working memory and speech comprehension deficits will be improved by operant training.; The results of the first experiment demonstrated a large drug effect (r = .98) on P3 amplitude, an ERP measure of auditory working memory and attention. The second experiment supported the hypothesis that operant training improves auditory working memory (p .05). The increase in span task ability related to improvements observed on a measure of speech comprehension over the course of training.; Practically, these results may have implications for treating problems of understanding, processing, and learning speech that impacts education (e.g., dyslexia) and psychotherapy (e.g., depression, psychosis). Theoretically, this clinical study elaborated a treatment effect at the neural, cognitive, and functional levels and furthered our understanding of the association among auditory attention, working memory, and speech comprehension.
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