Margaret A. Rogers

A Positron Emission Tomography Study of Binaurally and Dichotically Presented Stimuli: Effects of Level of Language and Directed Attention

Regional cerebral blood flow (rCBF) was measured using positron emission tomography with oxygen- 15 labeled water as 10 normal subjects listened to three types of auditory stimuli (environmental sounds, meaningless speech, and words) presented binaurally or dichotically. Binaurally presented environmental sounds and words caused similar bilateral rCBF increases in left and right superior temporal gyri. Dichotically presented stimuli (subjects attended to left or right ears) caused asymmetric activation in the temporal lobes, resulting from increased rCBF in temporal lobe regions contralateral to the attended ear and decreased rCBF in the opposite hemisphere. The results indicate that auditorily presented language and non-language stimuli activate similar temporal regions, that dichotic stimulation dramatically changes rCBF in temporal lobes, and that the change is due both to attentional mechanisms and to hemispheric specialization.

The effect of probabilistic phonotactics on lexical acquisition

The effect of probabilistic phonotactics on lexical acquisition in typically developing children was examined to determine whether a lexical or sublexical level of language processing dominates lexical acquisition. Sixty-one normally achieving 7, 10, and 13 year-old children participated in a word learning task, involving non-words of varying probabilistic phonotactics. Non-words were presented in a lecture format and recognition memory was tested following a 7 minute filled delay. Results showed that 10 and 13 year-old children recognized more high probability non-words than low probability non-words. In contrast, 7 year-old children showed no consistent effect of probabilistic phonotactics on lexical acquisition. These findings suggest that the sublexical level of processing dominates word learning during the initial phases in older children. This, in turn, raises questions about the mental representations of words and the effect of phonological knowledge on lexical acquisition in young children. Implic...The effect of probabilistic phonotactics on lexical acquisition in typically developing children was examined to determine whether a lexical or sublexical level of language processing dominates lexical acquisition. Sixty-one normally achieving 7, 10, and 13 year-old children participated in a word learning task, involving non-words of varying probabilistic phonotactics. Non-words were presented in a lecture format and recognition memory was tested following a 7 minute filled delay. Results showed that 10 and 13 year-old children recognized more high probability non-words than low probability non-words. In contrast, 7 year-old children showed no consistent effect of probabilistic phonotactics on lexical acquisition. These findings suggest that the sublexical level of processing dominates word learning during the initial phases in older children. This, in turn, raises questions about the mental representations of words and the effect of phonological knowledge on lexical acquisition in young children. Implications of these findings for children with specific language impairment (SLI) are discussed.

Speech motor programming in hypokinetic and ataxic dysarthria

It is widely accepted that the cerebellar and basal ganglia control circuits contribute to the programming of movement. Converging evidence from neuroimaging, limb control, and neuropsychological studies suggests that (1) people with cerebellar disease have reduced ability to program movement sequences in advance of movement onset and (2) people with Parkinsons disease are unable to maintain a programmed response or to rapidly switch between responses. Despite a substantial supporting literature, no studies have addressed these potential areas of speech programming disruption for speakers with ataxic and hypokinetic dysarthria. Control participants and adults with dysarthria completed speech reaction time protocols designed to capture these aspects of utterance preparation. Results provided initial support for processing deficits in speakers with ataxic and hypokinetic dysarthria that are separable from motor execution impairments.

Sound production treatment for apraxia of speech: overgeneralization and maintenance effects

This investigation was designed to examine the effects of a sound production training program on the production of selected sounds from a speaker with apraxia of speech and Brocas aphasia. Treatme...

Planning speech one syllable at a time: the reduced buffer capacity hypothesis in apraxia of speech

This investigation examined the phonologic similarity effect among individuals with aphasia (APH), with aphasia and apraxia of speech (APH/AOS) and normal controls (NC). Participants repeatedly produced pairs of rhyming words that contrasted with respect to the featural similarity of their onsets (i.e. shared voicing and manner, shared place and manner, no shared features). Rogers and Storkel (1998) used similar word pairs, but presented them one at a time, ostensibly requiring reprogramming of pre-motor processing buffers whenever a novel word was presented. They found that phonologic similarity delayed naming. In the present investigation, a parameter remapping task was used in which both words in the pair were presented before speakers began the rapid serial productions, thus alleviating the need to reprogram the processing buffer between the first and second word. Two measures of inter-word interval duration were obtained. The APH and NC groups showed no differences in inter-word interval length betwe...

Parameters of semantic and phonologic activation in speakers with aphasia with and without apraxia of speech

A cross-modal picture-word interference paradigm was employed to investigate parameters of semantic and phonologic activation in four speakers with aphasia (APH), four speakers with aphasia and a concomitant apraxia of speech (APH/AOS) and ten speakers with normal speech and language (NC). Participants named pictured objects in the context of listening to words that were either semantically or phonologically related to the picture labels. Relative to the presentation of the target picture, these semantic and phonologic interfering stimuli (IS) were presented at seven different temporal asynchronies, labelled stimulus onset asynchronies (SOA). Speech onset latencies were analysed and SOAs at which the semantic and phonologic IS began and ceased to slow naming latencies were obtained. The time course of semantic and phonologic processing was inferred using the following four activation parameters: (1) interference onset SOA; (2) interference offset SOA; (3) peak interference SOA; and (4) activation period. ...

Dual isotope brain SPECT imaging for monitoring cognitive activation: initial studies in humans

A dual isotope, single photon emission tomography (SPECT) technique using 99Tcm-hexamethylpropyleneamine oxime (HMPAO) and 123I-iodoamphetamine (IMP) was investigated to determine its suitability for assessing regional cerebral blood flow (rCBF) changes resulting from cognitive activation. The similarity of the 123I-IMP and 99Tcm-HMPAO distributions under the same physiological conditions was first investigated by administering the two agents to human subjects (n = 8) either simultaneously or at different times but during the performance of the same task. Normalized ratio images generated from the 99Tcm and 123I data showed that the two tracers distributed similarly in the left and right cerebral hemispheres when administered under similar physiological conditions. There was, however, a significant anterior/posterior gradient that appears to be the result of partial volume effects due to small differences in spatial resolution of the two agents. In two subjects, 99Tcm-HMPAO was administered during a resting period with eyes-closed and 123I-IMP was injected later during visual checkerboard stimulation. Ratio images showed a localized increase in the occipital lobes during the visual stimulation consistent with the expected increase in rCBF. The dual isotope strategy appears promising for study of changes in rCBF due to cognitive activation.

The vowel lengthening exaggeration effect in speakers with apraxia of speech: Compensation, artifact, or primary deficit?

Vowel duration functions contrastively in English to signal the voicing feature of syllable-final stop consonants. This study examines three hypotheses posited to explain why speakers with apraxia of speech and a concomitant aphasia exhibit an exaggerated vowel lengthening effect relative to speakers with dysarthria, aphasia without apraxia and controls. The investigation addresses the hypotheses that the vowel lengthening exaggeration effect is attributable to: (1) a compensatory strategy, (2) an artifact of slow speaking rate, (3) the concomitant language impairment, or (4) a primary deficit reflecting the underlying nature of the apraxia disorder. The results do not support the first three of these hypotheses. It is hypothesized that the temporal measures most likely to reveal abnormalities which are uniquely characteristic of speakers with apraxia of speech are those which are relational in nature, either with respect to inter- articulator timing or contrastive durations.

Features of Spontaneous Language in Speakers With Amyotrophic Lateral Sclerosis and Dysarthria

Language samples (picture description) produced by moderately dysarthric speakers with ALS were compared with those of gender- and age-matched controls. Results indicated that dysarthric speakers p...

The impact of dose on naming accuracy with persons with aphasia

Background: Although aphasia rehabilitation has been shown to be efficacious, many questions remain regarding how best to deliver treatment to maximise functional gains for persons with aphasia. Treatment-delivery variables, such as intensity and dosage, are likely to influence both behavioural and structural changes during anomia treatment. While numerous protocols have concluded that treatment intensity positively impacts functional outcomes, few studies to date have examined the role that dose plays in patient outcomes for anomia treatment. Aims: This study sought to investigate how manipulating dose of repeated confrontation naming within sessions influences naming in persons with aphasia. Repeated practice of confrontation naming, without feedback, was hypothesised to improve trained but not untrained words, to be persistent after withdrawal, and to be sensitive to the number of trials (i.e., dose) within sessions. Methods and Procedures: A single-subject ABA design, with replication across seven participants with aphasia, was used to investigate the influence of repeated confrontation naming attempts on the acquisition and maintenance of trained pictures relative to untrained pictures. Training involved repeated attempts to name pictures, along with repeated exposure to pictures of objects (nouns) and their names, without feedback. The primary independent variable was within session dose; the dependent variable was naming accuracy. Outcomes and Results: Naming accuracy improved for all participants for trained pictures across both acquisition and maintenance phases per visual inspection; such positive effects were not observed for untrained pictures. Effect-size calculations indicate that three of seven participants demonstrated considerable change for trained items, while one of seven participants demonstrated meaningful change for untrained items. The high-dose condition elicited small effect sizes for one participant, and large effect sizes for two of seven participants, while the low-dose condition elicited small and medium effect sizes for two of seven participants. Conclusions: Participants across a variety of aphasia severity levels responded positively to two doses of repeated confrontation naming practice, without feedback, across phases of this naming protocol. Results are in line with principles of neuroplasticity and demonstrate that repeated practice, without feedback, can produce significant and persistent changes in naming ability for some persons with aphasia.