Marina Laganaro

Predictors of picture naming speed.

We report the results of a large-scale picture naming experiment in which we evaluated the potential contribution of nine theoretically relevant factors to naming latencies. The experiment included a large number of items and a large sample of participants. In order to make this experiment as similar as possile to classic picture naming experiments, participants were familiarizedwith the materials during a training session. Speeded naming latencies were determined by a software key on the basis of the digital recording of the responses. The effects of various variables on these latencies were assessed with multiple regression techniques, using a repeated measures design. The interpretation of the observed effects is discussed in relation to previous studies and current views on lexical access during speech production.

Receptive amusia: temporal auditory processing deficit in a professional musician following a left temporo-parietal lesion

This study examined the musical processing in a professional musician who suffered from amusia after a left temporo-parietal stroke. The patient showed preserved metric judgement and normal performance in all aspects of melodic processing. By contrast, he lost the ability to discriminate or reproduce rhythms. Arrhythmia was only observed in the auditory modality: discrimination of auditorily presented rhythms was severely impaired, whereas performance was normal in the visual modality. Moreover, a length effect was observed in discrimination of rhythm, while this was not the case for melody discrimination. The arrhythmia could not be explained by low-level auditory processing impairments such as interval and length discrimination and the impairment was limited to auditory input, since the patient produced correct rhythmic patterns from a musical score. Since rhythm processing was selectively disturbed in the auditory modality, the arrhythmia cannot be attributed to a impairment of supra-modal temporal processing. Rather, our findings suggest modality-specific encoding of musical temporal information. Besides, it is proposed that the processing of auditory rhythmic sequences involves a specific left hemispheric temporal buffer.

Computerised treatment of anomia in acute aphasia: treatment intensity and training size.

In this study we analysed the outcome of computer-assisted therapy (CAT) for anomia on eight acute aphasic patients. Since therapy for anomia generally leads to an item-specific effect, the aim of the present study was to investigate whether it is possible to enhance recovery from anomia by increasing the number of treated items. Two periods of five daily written-naming CAT sessions were compared: In one period the CAT included one set of 48 words (single list) and in the other period a double list of 96 items was treated. Seven out of eight patients improved in naming performance for treated items. Overall gains were superior after practising the double list, despite fewer item repetitions. These results suggest that the size of the effect of therapy for anomia depends more on the number of treated items than on the number of repetitions per item. The integration of these results within the framework of studies on intensity is discussed.

Time course of word production in fast and slow speakers: a high density ERP topographic study

The transformation of an abstract concept into an articulated word is achieved through a series of encoding processes, which time course has been repeatedly investigated in the psycholinguistic and neuroimaging literature on single word production. The estimates of the time course issued from previous investigations represent the timing of process duration for mean processing speed: as production speed varies significantly across speakers, a crucial question is how the timing of encoding processing varies with speed. Here we investigated whether between-subjects variability in the speed of speech production is distributed along all encoding processes or if it is accounted for by a specific processing stage. We analysed event-related electroencephalographical (ERP) correlates during overt picture naming in 45 subjects divided into three speed subgroups according to their production latencies. Production speed modulated waveform amplitudes in the time window ranging from about 200 to 350 ms after picture presentation and the duration of a stable electrophysiological spatial configuration in the same time period. The remaining time windows from picture onset to 200 ms before articulation were unaffected by speed. By contrast, the manipulation of a psycholinguistic variable, word age-of-acquisition, modulated ERPs in all speed subgroups in a different and later time period, starting at around 400 ms after picture presentation, associated with phonological encoding processes. These results indicate that the between-subject variability in the speed of single word production is principally accounted for by the timing of a stable electrophysiological activity in the 200-350 ms time period, presumably associated with lexical selection.

Time course of evoked-potential changes in different forms of anomia in aphasia

Impaired word production after brain damage can be due to impairment at lexical–semantic or at lexical–phonological levels of word encoding. These processes are thought to involve different brain regions and to have different time courses. The present study investigated the time course of electrophysiological correlates of anomia in 16 aphasic speakers, divided in two subgroups according to their anomic pattern (8 with lexical–semantic impairment and 8 with lexical–phonological impairment), in comparison to 16 healthy control subjects performing the same picture naming task. Differences in amplitudes and in topographic maps between groups were differently distributed when the whole heterogeneous group of aphasic patients was compared to the control group and when the two more homogeneous subgroups of anomic patients were analyzed. The entire aphasic group expressed different waveforms and topographic patterns than the control group starting about 100 msec after picture presentation. When two subgroups of aphasic patients are considered according to the underlying cognitive impairment, early event-related potential (ERP) abnormalities (100–250 msec) appeared only in the lexical–semantic subgroup, whereas later ERP abnormalities (300–450 msec) occurred only in the lexical–phonological subgroup. These results indicate that the time windows of ERP abnormalities vary depending on the underlying anomic impairment. Moreover, the findings give support to current hypotheses on the time course of processes involved in word production during picture naming.

Selective impairment of lexical stress assignment in an italian-speaking aphasic patient

Psycholinguistic speech production models assume that lexical stress is stored and accessed separately during phonological encoding. We address the questions of the storage and computation of lexical stress in a case study of an Italian-speaking patient with an impairment of lexical stress assignment in naming, reading, and repeating single words. The patients stress error pattern and his performance on tasks examining lexical stress in perception suggest an impairment in the retrieval of the stress pattern of irregular words. In contrast, his assignment of stress to nonstored phonological forms suggests that the computation of stress is unimpaired.

Is there a syllable frequency effect in aphasia or in apraxia of speech or both

Background: The observation of a syllable frequency effect on production latencies in healthy speakers has been an argument in favour of stored syllables in speech production. In Levelt, Roelofs, and Meyers (1999) model of speech production, syllabic representations are accessed during phonetic encoding. Neurolinguistic studies have provided convergent evidence of a syllable frequency effect on production accuracy in speakers with acquired language disorders. However, the observation that syllable frequency also affected production in aphasic speakers with a pre‐phonetic impairment (conduction aphasia and Wernickes aphasia) seems in contradiction to the phonetic locus of syllabic representations. Aims: We illustrate the points of convergences and divergences between psycholinguistic and neurolinguistic results on the locus of the syllable frequency effect and explore whether a syllable frequency effect is observed in apraxia of speech (AoS) and in conduction aphasia when participants are tested with the same material. Methods & Procedures: Reading and repetition was elicited with monosyllabic words (Experiment A) and with bisyllabic pseudowords (Experiment B) composed of high‐ or low‐frequency syllables. Three speakers with AoS and three speakers with conduction aphasia participated in each experiment. Outcomes & Results: Both subgroups displayed a tendency for a syllable frequency effect on production accuracy. A significant effect of syllable frequency was observed in each experiment in a participant with AoS and in a participant with conduction aphasia. Conclusions: The data confirmed similar syllable frequency effects in speakers with AoS and in conduction aphasia when tested with the same eliciting material. We discuss these apparently contradictory observations and suggest an explanation for the origin of the syllable frequency effect in these two populations. I wish to thank Lindsey Nickels and Manuel Carreiras for their meticulous review and helpful comments on a previous version of the manuscript. Research supported by Swiss National Science Foundation Grant No. 105312‐108284.

Electrophysiological correlates of different anomic patterns in comparison with normal word production.

Different forms of anomia are observed in aphasia, which can be related to impaired semantic, lexical or phonological processes. In the present study, we analysed electrophysiological correlates of different patterns of anomia in six aphasic speakers. Event-related potentials (ERPs) were recorded during picture naming in each anomic speaker and in 15 healthy controls. Waveform analysis and temporal segmentation indicated a difference between high and low frequency words in the control group between 270 and 330 msec after picture onset. The ERPs recorded in the patients were compared to the control group. The time-windows of divergent ERP correlates were very similar between successful and erroneous naming, but they were differently distributed in the 6 patients. Two patients with conduction aphasia and impaired phonological encoding had normal electro-cortical activity during the first 300 msec and abnormal patterns between 300 and 450 msec. Two patients with lexical-semantic impairment had earlier ERP abnormalities starting immediately after visual processes. The two patients with less severe anomia and preponderance of omission errors displayed abnormal ERPs between 280 and 350 msec. These results indicate that abnormal electro-cortical correlates of anomic profiles can be observed in different time-windows, which seem to correspond to the time course of the impaired encoding processes.

French normative data and naming times for action pictures

The aim of the present study was to provide French normative data for 112 action line drawings. The set of action pictures consisted of 71 drawings taken from Masterson and Druks (1998) and 41 additional drawings. It was standardized on six psycholinguistic variables—that is, name agreement, image agreement, image variability, visual complexity, conceptual familiarity, and age of acquisition (AoA). Naming latencies to the action pictures were collected, and a regression analysis was performed on the naming latencies, with the standardized variables, as well as with word frequency and length, taken as predictors. A reliable influence of AoA, name agreement, and image agreement on the naming latencies was observed. The findings are consistent with previous published studies in other languages. The full set of these norms may be downloaded fromwww.psychonomic.org/archive/.

Computerised treatment of anomia in chronic and acute aphasia: An exploratory study

Background: Studies on computer assisted therapy (CAT) show encouraging outcomes with chronic aphasic speakers. However, there have been no studies investigating efficacy of CAT carried out with acute in-patients. Aims: This paper aims to evaluate the effects and feasibility of an unsupervised computer-based therapy for anomia in chronic out-patient and acute in-patient aphasic participants. The computerised training programmes were selected according to each participants anomic syndrome. Methods & Procedures: A multiple single-case design was used with two subgroups of aphasic participants. In the out-patients group (N = 4), CAT sessions were alternated with an equal number of clinical treatment sessions. In a second group of seven in-patients with acute aphasia, CAT was added to daily individual aphasia therapy. Outcomes & Results : In four chronic out-patients, a significant item-specific effect of CAT was shown. For two participants, this effect was similar to the effect of an equal number of individual clinical therapy sessions. Results were more heterogeneous in the in-patient group: an item-specific effect of CAT, not accounted for by spontaneous recovery, was observed in three of the seven participants. Conclusions: The present data suggest that individually adapted CAT can be effective as an adjunct to clinical therapy for anomia, not only with chronic aphasic out-patients but also in acute in-patients. Further investigation is needed in order to specify the conditions of application of CAT, given the varied results among our participants specially in the in-patients group.