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Purpose: The clinical use of event-related potentials in patients with language disorders is increasingly acknowledged. For this purpose, normative data should be available. Within this context, healthy aging and gender effects on the electrophysiological correlates of semantic sentence comprehension were investigated. Method: One hundred and ten healthy subjects (55 men and 55 women), divided among three age groups (young, middle aged, and elderly), performed a semantic sentence congruity task in the visual modality during electroencephalographic recording. Results: The early visual complex was affected by increasing age as shown by smaller P2 amplitudes in the elderly compared to the young. Moreover, the N400 effect in the elderly was smaller than in the young and was delayed compared to latency measures in both middle-aged and young subjects. The topography of age-related amplitude changes of the N400 effect appeared to be gender specific. The late positive complex effect was increased at frontal electrode sites from middle age on, but this was not statistically significant. No gender effects were detected regarding the early P1, N1, and P2, or the late positive complex effect. Conclusion: Especially aging effects were found during semantic sentence comprehension, and this from the level of perceptual processing on. Normative data are now available for clinical use.

Background The semantic variant of primary progressive aphasia (PPA) is typically associated with a loss of semantic knowledge. Research on the semantic processing in the other clinical variants of PPA is, however, rather sparse and limited to off-line behavioural studies. Aims This study aimed to investigate verbal semantic processing in patients with the three variants of PPA by the event-related potential technique. The presence, latency, amplitude and/or topographic distribution of the N400 effect may be helpful in the diagnosis of PPA and its clinical variants and it provides temporal information about semantic processing (disturbances) in the three variants of PPA. Methods & Procedures The N400 effect was studied by a categorical word-priming paradigm and a semantic-anomaly paradigm at sentence level in eight persons with PPA(-plus) and 30 age-matched healthy controls. The mean amplitudes and onset latencies of the N400 effect were compared between each patient and the control group by two methods that are applicable in clinical practice, namely visual inspection and Z-scores. Outcomes & Results The N400 effect elicited by the categorical-priming paradigm was only present in the two patients with the non-fluent variant of PPA. This effect was absent in the two patients with the semantic variant(-plus), two patients with the logopenic variant(-plus), one patient with the non-fluent variant-plus, and the patient with PPA not otherwise specified. The results of the N400 effect elicited by the semantic-anomaly task at the sentence level were variable, but differences in the presence, mean amplitudes, onset latencies and/or topographic distributions of the effect were found in all patients with PPA(-plus) in comparison with the control group. Conclusions & Implications The results of our study showed that the evaluation of the N400 effect might have an added value in the diagnostic process of PPA in general and in the differentiation of patients with the non-fluent variant from patients with the logopenic and semantic variants. Furthermore, our results indicate the presence of difficulties with retrieving stored semantic knowledge or semantic integration of a word in the preceding context in patients with the three variants of PPA. These findings might help the speech-language pathologist in determining individualized therapy goals and indicate that it might be helpful to focus on verbal semantic processing in language therapy in patients with the three variants of PPA and not only in patients with the semantic variant. What this paper adds What is already known on the subject The semantic variant of PPA is characterized by an impaired object knowledge and single-word comprehension and these functions are relatively spared in the non-fluent and logopenic variants following the guidelines of Gorno-Tempini et al. (2011). Research on the semantic processing in patients with the non-fluent and logopenic variant is, however, rather sparse and limited to off-line behavioural studies. Only four group studies investigated verbal semantic processing by the N400 effect, and these studies indicate disturbances in the three variants of PPA. What this paper adds to existing knowledge Our results indicate the presence of difficulties with retrieving stored semantic knowledge or semantic integration of a word in the preceding context during a semantic-priming paradigm in patients with the semantic and logopenic variants of PPA and during a semantic-anomaly task at the sentence level in patients with the three variants of PPA. What are the potential or actual clinical implications of this work? The results of our study showed that the evaluation of the N400 effect might have an added value in the diagnostic process of PPA in general and in the differentiation of patients with the non-fluent variant from patients with the logopenic and semantic variants. The evaluation of the N400 effect might also help the speech-language pathologist in determining individualized therapy goals and indicate that it might be helpful to focus on verbal semantic processing in language therapy in patients with the three variants of PPA and not only in patients with the semantic variant.

Categorical and associative relationships among words are two key forms of semantic knowledge. In this study, we examined ageing and gender effects on the processing of both types of semantic relat...

Purpose This systematic review aimed to establish language and speech markers to support the clinical diagnosis of primary progressive aphasia (PPA) and its clinical phenotypes. Our first objective was to identify behavioral language and speech markers of early-stage PPA. Our second objective was to identify the electrophysiological correlates of the language and speech characteristics in PPA. Method The databases MEDLINE, Web of Science, and Embase were searched for relevant articles. To identify behavioral markers, the initial subjective complaints and the language and speech deficits detected during the initial diagnostic evaluation were summarized for PPA in general and each clinical variant according to the 2011 consensus diagnostic criteria (nonfluent variant [NFV], semantic variant, and logopenic variant [LV]). To identify electrophysiological markers, the studies in which event-related potentials (ERPs) were elicited by a language or speech paradigm in patients with PPA were included. Results In total, 114 relevant studies were identified, including 110 behavioral studies and only four electrophysiological studies. This review suggests that patients with the semantic variant could be accurately differentiated from the NFV and LV in the initial stages based on the consensus criteria. Nonetheless, the early differentiation between the NFV and LV is not straightforward. In the four electrophysiological studies, differences in the latency, amplitude, and topographical distribution of the semantic N400 component were found between patients with PPA and healthy controls. Conclusions To accurately differentiate the NFV from the LV, it could be important to assess the language and speech degeneration by more specific assessments and by more objective diagnostic methods that offer insights into the language-related processes. Electrophysiological markers of PPA were not identified in this review due to the low number of studies that investigated language-related ERPs. More controlled ERP studies in larger patient cohorts are needed to investigate the diagnostic applicability of language-related ERPs in PPA. Supplemental Material https://doi.org/10.23641/asha.12798080

Semantic processing is a fundamental aspect in human communication. The cortical organization of semantic processing has been exhaustively described, in contrast to inconsistent results on the function of subcortical grey matter structures. Hence, this manuscript reports a systematic review and meta-analysis on the subcortical involvement in verbal semantic comprehension in healthy individuals. The 50 included studies indicate specific contributions by the cerebellum, thalamus and caudate nucleus respectively. In particular, the right posterior cerebellum is proposed to be involved in a semantic executive system and in adequate decision-making. The left thalamus, regulated by the caudate nucleus, might function as a subcortical hub, controlling the access and integration of cortically organized semantic features. Furthermore, a contribution of the cerebellum, thalamus and caudate nucleus in semantic prediction generation and evaluation at sentence level is preliminarily suggested. More research is required to gain insights into the role of the putamen, globus pallidus and subthalamic nucleus.

Language-related potentials are increasingly used to objectify (mal)adaptive neuroplasticity in stroke-related aphasia recovery. Using preattentive [mismatch negativity (MMN)] and attentive (P300) phonologically related paradigms, neuroplasticity in sensory memory and cognitive functioning underlying phonological processing can be investigated. In aphasic patients, MMN amplitudes are generally reduced for speech sounds with a topographic source distribution in the right hemisphere. For P300 amplitudes and latencies, both normal and abnormal results have been reported. The current study investigates the preattentive and attentive phonological discrimination ability in 17 aphasic patients (6 monolinguals and 11 bilinguals, aged 41–71 years) at two timepoints during aphasia recovery. Between the two timepoints, a significant improvement of behavioral language performance in both languages is observed in all patients with the MMN latency at timepoint 1 as a predictive factor for aphasia recovery. In contrast to monolinguals, bilingual aphasic patients have a higher probability to improve their processing speed during rehabilitation, resulting in a shortening of the MMN latency over time, which sometimes progresses toward the normative values.

Stroke in the language dominant hemisphere is the most frequent cause of aphasia. In the course of post-stroke aphasia different mechanisms can contribute to the recovery of language: recovery from ischemia, compensatory rerouting of language modalities and neuroplasticity occur at different time scales after the initial injury. These mechanisms may occur spontaneously or may be induced or influenced by various therapeutic interventions. This report contains a systematic review of the literature concerning the debated role of the right hemisphere in the recovery from stroke-related aphasia. The existing literature was approached using the PICOS principle and well-established inclusion and exclusion criteria. Although many gaps remain in the knowledge on the role of the right hemisphere, there is some evidence of a facilitation of spontaneous language recovery in the acute and subacute phase. In the subacute and chronic phase, the right hemisphere homologous language areas, along with memory and attention-related areas, facilitate treatment related improvement. In contrast, in therapy-free periods in the chronic stage, the right hemisphere no longer contributes to language recovery or may even be inhibitory. Injury-, language- and therapy-related variables impact on the role of the right hemisphere in aphasia recovery.

Recovery of stroke-related aphasia can be affected by language therapy in the early and chronic stage. Objectively monitoring therapy-induced neuroplasticity is possible by several measurement techniques including electro- and magneto-encephalography. The obtained event-related potentials (ERPs) and fields (ERFs) provide insights into the neural basis of intact or deficient language processing with milliseconds precision. In this literature review, we highlight the sensitivity of ERPs and ERFs to logopedic interventions by providing an overview of therapy-induced changes in the amplitude, latency and topography of early and mid-to-late components.

Background: Recovery from stroke-related aphasia follows different stages, evolving from the acute and subacute phase (< 6 months post stroke) into the chronic phase (> 6 months post stroke). In general, phonology remains tenaciously disturbed, making it a relevant language marker to assess in every stage of recovery. The classical behavioural evaluation of phonological abilities in patients with aphasia can be extended with a registration of event-related potentials (ERPs), for example the Mismatch Negativity (MMN) and the P300. ERPs have been suggested 1) to contain indications towards the language recovery progress (Nolfe et al., 2006) and 2) to provide additional and (more) sensitive information along with the behavioural results (Aerts, Batens et al., 2015). In this longitudinal study, we aimed to corroborate these previous findings. Methods and procedures: In four patients with aphasia after a first-ever stroke, we administered behavioural language tasks as well as phonological ERPs in the (sub)acute and in the chronic stage of recovery. Outcomes and results: The results demonstrate that the early presence of a P300 could be considered as an indicator of better recovery of language comprehension over time. For the MMN, such an indicative value remains to be confirmed. Moreover, abnormal ERP amplitudes or latencies accompanied behavioural ceiling effects in the chronic stage, suggesting a sensitivity of phonological ERPs for subtle language deficits that could not be detected by the established behavioural instruments. Conclusions: The added values of phonological ERPs advocate their implementation in aphasia rehabilitation.

Purpose: This systematic review aimed to establish language and speech markers to support the clinical diagnosis of primary progressive aphasia (PPA) and its clinical phenotypes. Our first objective was to identify behavioral language and speech markers of early-stage PPA. Our second objective was to identify the electrophysiological correlates of the language and speech characteristics in PPA.Method: The databases MEDLINE, Web of Science, and Embase were searched for relevant articles. To identify behavioral markers, the initial subjective complaints and the language and speech deficits detected during the initial diagnostic evaluation were summarized for PPA in general and each clinical variant according to the 2011 consensus diagnostic criteria (nonfluent variant [NFV], semantic variant, and logopenic variant [LV]). To identify electrophysiological markers, the studies in which event-related potentials (ERPs) were elicited by a language or speech paradigm in patients with PPA were included.Results: In total, 114 relevant studies were identified, including 110 behavioral studies and only four electrophysiological studies. This review suggests that patients with the semantic variant could be accurately differentiated from the NFV and LV in the initial stages based on the consensus criteria. Nonetheless, the early differentiation between the NFV and LV is not straightforward. In the four electrophysiological studies, differences in the latency, amplitude, and topographical distribution of the semantic N400 component were found between patients with PPA and healthy controls. Conclusions: To accurately differentiate the NFV from the LV, it could be important to assess the language and speech degeneration by more specific assessments and by more objective diagnostic methods that offer insights into the language-related processes. Electrophysiological markers of PPA were not identified in this review due to the low number of studies that investigated language-related ERPs. More controlled ERP studies in larger patient cohorts are needed to investigate the diagnostic applicability of language-related ERPs in PPA.Supplemental Material S1. Search strategies.Supplemental Material S2. Quality assessments and results.Supplemental Material S3. Demographic characteristics.Stalpaert, J., Cocquyt, E.-M., Criel, Y., Segers, L., Miatton, M., Van Langenhove, T., van Mierlo, P., & De Letter, M. (2020). Language and speech markers of primary progressive aphasia: A systematic review. American Journal of Speech-Language Pathology. https://doi.org/10.1044/2020_AJSLP-20-00008

From a holistic point of view, semantic processes are subserved by large-scale subcortico-cortical networks. The dynamic routing of information between grey matter structures depends on the integrity of subcortical white matter pathways. Nonetheless, controversy remains on which of these pathways support semantic processing. Therefore, a systematic review of the literature was performed with a focus on anatomo-functional correlations obtained from direct electrostimulation during awake tumor surgery, and conducted between di usion tensor imaging metrics and behavioral semantic performance in healthy and aphasic individuals. The 43 included studies suggest that the left inferior fronto-occipital fasciculus contributes to the essential connectivity that allows semantic processing. However, it remains uncertain whether its contributive role is limited to the or- ganization of semantic knowledge or extends to the level of semantic control. Moreover, the functionality of the left uncinate fasciculus, inferior longitudinal fasciculus and the posterior segment of the indirect arcuate fas- ciculus in semantic processing has to be con rmed by future research.