Temporal processing capabilities in repetition conduction aphasia

Acoustic and phonemic processing are impaired in individuals with aphasia

Acoustic and phonemic processing are understudied in aphasia, a language disorder that can affect different levels and modalities of language processing. For successful speech comprehension, processing of the speech envelope is necessary, which relates to amplitude changes over time (e.g., the rise times). Moreover, to identify speech sounds (i.e., phonemes), efficient processing of spectro-temporal changes as reflected in formant transitions is essential. Given the underrepresentation of aphasia studies on these aspects, we tested rise time processing and phoneme identification in 29 individuals with post-stroke aphasia and 23 healthy age-matched controls. We found significantly lower performance in the aphasia group than in the control group on both tasks, even when controlling for individual differences in hearing levels and cognitive functioning. Further, by conducting an individual deviance analysis, we found a low-level acoustic or phonemic processing impairment in 76% of individuals with aphasia. Additionally, we investigated whether this impairment would propagate to higher-level language processing and found that rise time processing predicts phonological processing performance in individuals with aphasia. These findings show that it is important to develop diagnostic and treatment tools that target low-level language processing mechanisms.

[Conduction aphasia in patients with glioma in the left hemisphere]

Background. According to Wernicke-Geschwind model, conduction aphasia following arcuate tract lesion was canonized as primary disorder of repetition in relatively intact speech.

OBJECTIVE

Syndromic analysis of speech and writing disorders in patients with arcuate tract lesion using the method by A.R. Luria and their comparison with well-known types of aphasia.

MATERIAL AND METHODS

Clinical and neuropsychological survey was performed in 14 patients with gliomas who underwent surgical treatment at the Burdenko Neurosurgical Center (10 gliomas of the frontal lobe and 4 tumors of the temporal lobe). All patients underwent MRI, HARDI MRI tractography and A.R. Luria's neuropsychological examination prior to surgery and after 5-6 postoperative days. Thirteen patients underwent awake craniotomy, 3 of them were examined one year after surgery.

RESULTS

In all patients, the tumor was localized near arcuate tract and its infiltration was noted. No intraoperative damage to the tract was ever noted according to speech monitoring data. However, postoperative edema followed by infiltration and dislocation of the tract (in all patients), as well as local ischemia in 4 patients were observed. After resection of prefrontal and premotor gliomas, aphasia included frontal (perseveration) and temporal components (disorders of naming, auditory-speech memory). Unusual verbal paraphrases were noted. We also observed severe violation of writing (temporal type) even if spontaneous speech and repetition were preserved. In case of resection of deep posterior temporal gliomas, speech disorders included signs of frontal lobe lesion (perseveration) and writing disorders. Similar motor abnormalities were identified in writing.

CONCLUSION

Arcuate tract lesion can result speech and writing disorders as signs of damage to certain cortical speech zones (frontal and temporal lobe). Violations of repetition were not predominant in any case. At the same time, interruption of connection between motor and auditory image of the word could be revealed in writing.

The Treatment Based on Temporal Information Processing Reduces Speech Comprehension Deficits in Aphasic Subjects

Experimental studies have reported a close association between temporal information processing (TIP) and language comprehension. Brain-injured subjects with aphasia show disturbed TIP which was evidenced in elevated temporal order threshold (TOT) as compared to control subjects. The present study is aimed at improving auditory speech comprehension in aphasic subjects using a specific temporal treatment. Fourteen patients having deficits in both speech comprehension and TIP were tested. The Token Test, phoneme discrimination tests (PDT) and Voice-Onset-Time (VOT) Test were employed to assess speech comprehension. The TOT was measured using two 10 ms tones (400 Hz, 3000 Hz) presented binaurally. The patients participated in eight 45-min sessions of either the specific temporal treatment (n = 7) aimed at improving the perception of sequencing abilities, or in a non-temporal control treatment (n = 7) on volume discrimination. The temporal treatment yielded an improvement in TIP. Moreover, a transfer of improvement from the time domain to the language domain was observed. The control treatment did not improve either TIP or speech comprehension in any of the applied tests.

The use of standardised short-term and working memory tests in aphasia research: a systematic review

Impairments of short-term and working memory (STM, WM), both verbal and non-verbal, are ubiquitous in aphasia. Increasing interest in assessing STM and WM in aphasia research and clinical practice as well as a growing evidence base of STM/WM treatments for aphasia warrant an understanding of the range of standardised STM/WM measures that have been utilised in aphasia. To date, however, no previous systematic review has focused on aphasia. Accordingly, the goals of this systematic review were: (1) to identify standardised tests of STM and WM utilised in the aphasia literature, (2) to evaluate critically the psychometric strength of these tests, and (3) to appraise critically the quality of the investigations utilising these tests. Results revealed that a very limited number of standardised tests, in the verbal and non-verbal domains, had robust psychometric properties. Standardisation samples to elicit normative data were often small, and most measures exhibited poor validity and reliability properties. Studies using these tests inconsistently documented demographic and aphasia variables essential to interpreting STM/WM test outcomes. In light of these findings, recommendations are provided to foster, in the future, consistency across aphasia studies and confidence in STM/WM tests as assessment and treatment outcome measures.

The Application of Timing in Therapy of Children and Adults with Language Disorders

A number of evidence revealed a link between temporal information processing (TIP) and language. Both literature data and results of our studies indicated an overlapping of deficient TIP and disordered language, pointing to the existence of an association between these two functions. On this background the new approach is to apply such knowledge in therapy of patients suffering from language disorders. In two studies we asked the following questions: (1) can the temporal training reduce language deficits in aphasic patients (Study 1) or in children with specific language impairment (SLI, Study 2)? (2) can such training ameliorate also the other cognitive functions? Each of these studies employed pre-training assessment, training application, post-training and follow-up assessment. In Study 1 we tested 28 patients suffering from post-stroke aphasia. They were assigned either to the temporal training (Group A, n = 15) in milliseconds range, or to the non-temporal training (Group B, n = 13). Following the training we found only in Group A improved TIP, accompanied by a transfer of improvement to language and working memory functions. In Study 2 we tested 32 children aged from 5 to 8 years, affected by SLI who were classified into the temporal training (Group A, n = 17) or non-temporal training (Group B, n = 15). Group A underwent the multileveled audio-visual computer training Dr. Neuronowski^®, recently developed in our laboratory. Group B performed the computer speech therapy exercises extended by playing computer games. Similarly as in Study 1, in Group A we found significant improvements of TIP, auditory comprehension and working memory. These results indicated benefits of temporal training for amelioration of language and other cognitive functions in both aphasic patients and children with SLI. The novel powerful therapy tools provide evidence for future promising clinical applications.

Temporal information processing as a basis for auditory comprehension: clinical evidence from aphasic patients

BACKGROUND

Temporal information processing (TIP) underlies many aspects of cognitive functions like language, motor control, learning, memory, attention, etc. Millisecond timing may be assessed by sequencing abilities, e.g. the perception of event order. It may be measured with auditory temporal-order-threshold (TOT), i.e. a minimum time gap separating two successive stimuli necessary for a subject to report their temporal order correctly, thus the relation 'before-after'. Neuropsychological evidence has indicated elevated TOT values (corresponding to deteriorated time perception) in different clinical groups, such as aphasic patients, dyslexic subjects or children with specific language impairment.

AIMS

To test relationships between elevated TOT and declined cognitive functions in brain-injured patients suffering from post-stroke aphasia.

METHODS & PROCEDURES

We tested 30 aphasic patients (13 male, 17 female), aged between 50 and 81 years. TIP comprised assessment of TOT. Auditory comprehension was assessed with the selected language tests, i.e. Token Test, Phoneme Discrimination Test (PDT) and Voice-Onset-Time Test (VOT), while two aspects of attentional resources (i.e. alertness and vigilance) were measured using the Test of Attentional Performance (TAP) battery.

OUTCOMES & RESULTS

Significant correlations were indicated between elevated values of TOT and deteriorated performance on all applied language tests. Moreover, significant correlations were evidenced between elevated TOT and alertness. Finally, positive correlations were found between particular language tests, i.e. (1) Token Test and PDT; (2) Token Test and VOT Test; and (3) PDT and VOT Test, as well as between PDT and both attentional tasks.

CONCLUSIONS & IMPLICATIONS

These results provide further clinical evidence supporting the thesis that TIP constitutes the core process incorporated in both language and attentional resources. The novel value of the present study is the indication for the first time in Slavic language users a clear coexistence of the 'timing-auditory comprehension-attention' relationships.

Temporal Resolution of the Normal Ear in Listeners with Unilateral Hearing Impairment

Unilateral hearing loss (UHL) leads to an imbalanced input to the brain and results in cortical reorganization. In listeners with unilateral impairments, while the perceptual deficits associated with the impaired ear are well documented, less is known regarding the auditory processing in the unimpaired, clinically normal ear. It is commonly accepted that perceptual consequences are unlikely to occur in the normal ear for listeners with UHL. This study investigated whether the temporal resolution in the normal-hearing (NH) ear of listeners with long-standing UHL is similar to those in listeners with NH. Temporal resolution was assayed via measuring gap detection thresholds (GDTs) in within- and between-channel paradigms. GDTs were assessed in the normal ear of adults with long-standing, severe-to-profound UHL (N = 13) and age-matched, NH listeners (N = 22) at two presentation levels (30 and 55 dB sensation level). Analysis indicated that within-channel GDTs for listeners with UHL were not significantly different than those for the NH subject group, but the between-channel GDTs for listeners with UHL were poorer (by greater than a factor of 2) than those for the listeners with NH. The hearing thresholds in the normal or impaired ears were not associated with the elevated between-channel GDTs for listeners with UHL. Contrary to the common assumption that auditory processing capabilities are preserved for the normal ear in listeners with UHL, the current study demonstrated that a long-standing unilateral hearing impairment may adversely affect auditory perception--temporal resolution--in the clinically normal ear. From a translational perspective, these findings imply that the temporal processing deficits in the unimpaired ear of listeners with unilateral hearing impairments may contribute to their overall auditory perceptual difficulties.

The relationship between verbal and nonverbal auditory signal processing in conduction aphasia: behavioral and anatomical evidence for common decoding mechanisms

The processing of nonverbal auditory stimuli has not yet been sufficiently investigated in patients with aphasia. On the basis of a duration discrimination task, we examined whether patients with left-sided cerebrovascular lesions were able to perceive time differences in the scale of approximately 150 ms. Further linguistic and memory-related tasks were used to characterize more exactly the relationships in the performances between auditory nonverbal task and selective linguistic or mnemonic disturbances. All examined conduction aphasics showed increased thresholds in the duration discrimination task. The low thresholds on this task were in a strong correlative relation to the reduced performances in repetition and working memory task. This was interpreted as an indication of a pronounced disturbance in integrating auditory verbal information into a long-term window (sampling disturbance) resulting in an additional load of working memory. In order to determine the lesion topography of patients with sampling disturbances, the anatomical and psychophysical data were correlated on the basis of a voxelwise statistical approach. It was found that tissue damage extending through the insula, the posterior superior temporal gyrus, and the supramarginal gyrus causes impairments in sequencing of time-sensitive information.

Temporal order perception of auditory stimuli is selectively modified by tonal and non-tonal language environments

The close relationship between temporal perception and speech processing is well established. The present study focused on the specific question whether the speech environment could influence temporal order perception in subjects whose language backgrounds are distinctively different, i.e., Chinese (tonal language) vs. Polish (non-tonal language). Temporal order thresholds were measured for both monaurally presented clicks and binaurally presented tone pairs. Whereas the click experiment showed similar order thresholds for the two language groups, the experiment with tone pairs resulted in different observations: while Chinese demonstrated better performance in discriminating the temporal order of two "close frequency" tone pairs (600 Hz and 1200 Hz), Polish subjects showed a reversed pattern, i.e., better performance for "distant frequency" tone pairs (400 Hz and 3000 Hz). These results indicate on the one hand a common temporal mechanism for perceiving the order of two monaurally presented stimuli, and on the other hand neuronal plasticity for perceiving the order of frequency-related auditory stimuli. We conclude that the auditory brain is modified with respect to temporal processing by long-term exposure to a tonal or a non-tonal language. As a consequence of such an exposure different cognitive modes of operation (analytic vs. holistic) are selected: the analytic mode is adopted for "distant frequency" tone pairs in Chinese and for "close frequency" tone pairs in Polish subjects, whereas the holistic mode is selected for "close frequency" tone pairs in Chinese and for "distant frequency" tone pairs in Polish subjects, reflecting a double dissociation of function.

Assessment of Attention in People With Aphasia: Challenges and Recommendations

Assessing nonverbal cognitive constructs, such as attention, in persons with aphasia is particularly challenging. The most difficult aspect of this task is determining whether language deficits are independent of attention deficits or whether the pattern of preserved and impaired performance reflects a combination of deficits of language and attention. As difficult as the task of assessing attention in people with aphasia may be, teasing apart contributions of language and attention to communication is crucial for appropriate treatment planning and goal-setting for people with communication deficits. Assessment tools, both standardized and non-standardized, are reviewed to help in determining the extent to which types of attention are affected in people with aphasia.