Spoken Word Comprehension Research Articles

QOL-24. TREATMENT- AND TIME-RELATED IMPACT ON LONG-TERM NEUROCOGNITIVE OUTCOMES IN ADULT SURVIVORS OF A PEDIATRIC BRAIN TUMOR

Abstract Treatment for pediatric brain tumors has been associated with the risk of developing long-term neurocognitive impairment. However, it is not well understood which neurocognitive profiles exist within this population. We investigated neurocognitive functioning (NF) in survivors in early adulthood and aimed to assess the impact of radiotherapy dose (RTD) and time since treatment (TxT) on NF. Forty-six survivors of pediatric brain tumors (mean age 23.99±4.71, mean age at diagnosis 9.29±4.54) performed an extensive neurocognitive test battery resulting in intelligence (n=5), memory (n=2), and language (n=3) scores. NF in long-term survivors was compared to sex-, age-, and education-matched controls, and between the different treatment strategies (surgery-only n=19, chemotherapy n=8, radiotherapy n=11, or chemo-radiotherapy n=8). Furthermore, relation between max-RTD (range 40.28 – 61.61 Gy) as well as TxT and NF was assessed. Three ANCOVA models were tested, and false discovery rate (FDR) was applied. For all scales and domain scores, survivors scored lower compared to controls. Scores were significant lower on full scale intelligence (pfdr< 0.001), verbal comprehension (pfdr< 0.001), working memory (pfdr= 0.003), perceptual reasoning (pfdr< 0.001), processing speed (pfdr< 0.001), spoken word comprehension (pfdr= 0.001), and semantic word generation (pfdr= 0.036) compared to controls. NF was not significantly different between the different treatments, nor did the association with max-RTD reach significance. TxT was associated with verbal comprehension and spoken word comprehension; albeit significance was not retained after FDR correction. In this study, the overall survivor cohort scored lower on multiple cognitive outcomes. More detailed analysis of various risk factors might further elucidate the different neurocognitive profiles for this population. Furthermore, more detailed analysis of RTD distributions and affected brain structures may provide greater insight on the impact of radiotherapy on NF.

Continuous cursor-captured conceptual competition: Investigating the spatiotemporal dynamics of spoken word comprehension.

Semantically related concepts are coactivated during spoken word comprehension. Two internet-mediated cursor-tracking experiments examined the spatiotemporal dynamics of this coactivation. Participants viewed visual arrays containing images of a target (e.g., accordion) and a semantically related (e.g., banjo) or unrelated (e.g., plum) distractor whilst hearing the target word (e.g., "accordion"). Participants were tasked with moving their cursor from the bottom of the visual array to the target in one of the upper corners. In contrast to Experiment 1, the onset of stimulus presentation was triggered by cursor movement in Experiment 2. Across both experiments, temporal (e.g., RT) and spatial (e.g., AUC) measures revealed significantly greater attraction to images of semantically related compared with unrelated distractors. These results reveal that online cursor-tracking methods are sensitive to semantic competition and suitable for studying the activation of semantic knowledge during language comprehension.

Lesions that do or do not impair digit span: a study of 816 stroke survivors.

Prior studies have reported inconsistency in the lesion sites associated with verbal short-term memory impairments. Here we asked: How many different lesion sites can account for selective impairments in verbal short-term memory that persist over time, and how consistently do these lesion sites impair verbal short-term memory? We assessed verbal short-term memory impairments using a forward digit span task from the Comprehensive Aphasia Test. First, we identified the incidence of digit span impairments in a sample of 816 stroke survivors (541 males/275 females; age at stroke onset 56 ± 13 years; time post-stroke 4.4 ± 5.2 years). Second, we studied the lesion sites in a subgroup of these patients (n = 39) with left hemisphere damage and selective digit span impairment—defined as impaired digit span with unimpaired spoken picture naming and spoken word comprehension (tests of speech production and speech perception, respectively). Third, we examined how often these lesion sites were observed in patients who either had no digit span impairments or digit span impairments that co-occurred with difficulties in speech perception and/or production tasks. Digit span impairments were observed in 222/816 patients. Almost all (199/222 = 90%) had left hemisphere damage to five small regions in basal ganglia and/or temporo-parietal areas. Even complete damage to one or more of these five regions was not consistently associated with persistent digit span impairment. However, when the same regions were spared, only 5% (23/455) presented with digit span impairments. These data suggest that verbal short-term memory impairments are most consistently associated with damage to left temporo-parietal and basal ganglia structures. Sparing of these regions very rarely results in persistently poor verbal short-term memory. These findings have clinical implications for predicting recovery of verbal short-term memory after stroke.

Efficacy of spoken word comprehension therapy in patients with chronic aphasia: a cross-over randomised controlled trial with structural imaging

ObjectiveThe efficacy of spoken language comprehension therapies for persons with aphasia remains equivocal. We investigated the efficacy of a self-led therapy app, ‘Listen-In’, and examined the relation between brain structure...

The Comprehension Boost in Early Word Learning: Older Infants Are Better Learners.

Recent research has revealed that infants begin understanding words at around 6 months. After that, infants' comprehension vocabulary increases gradually in a linear way over 8-18 months, according to data from parental checklists. In contrast, infants' word comprehension improves robustly, qualitatively, and in a nonlinear way just after their first birthday, according to data from studies on spoken word comprehension. In this review, I integrate observational and experimental data to explain these divergent results. I argue that infants' comprehension boost is not well-explained by changes in their language input for common words, but rather by proposing that they learn to take better advantage of relatively stable input data. Next, I propose potentially complementary theoretical accounts of what makes older infants better learners. Finally, I suggest how the research community can expand our empirical base in this understudied area, and why doing so will inform our knowledge about child development.

Neural processing critical for distinguishing between speech sounds

We aimed to identify neural regions where ischemia acutely after stroke is associated with impairment in phoneme discrimination, and to determine whether such deficits are associated with impairment of spoken word comprehension. We evaluated 33 patients within 48 h of left hemisphere ischemic stroke onset with tests of phoneme discrimination and word-picture matching. We identified Pearson correlations between accuracy in phoneme discrimination and accuracy of word comprehension and identified areas where the percentage of infarcted tissue was associated with severity of phoneme discrimination deficit. We found that 54% had deficits in phoneme discrimination relative to healthy controls. Accuracy in phoneme discrimination correlated with accuracy on word comprehension tests. Damage to left intraparietal sulcus and hypoperfusion and/or infarct of left superior temporal gyrus were associated with phoneme discrimination deficits acutely, although patients with these lesions showed improvement or resolution of the deficit by six months.

Visual working memory load constrains language non-selective activation under task-demands

Abstract Visual world studies with bilinguals have demonstrated spontaneous cross-linguistic activations. In two experiments, we examined whether concurrent visual working memory (VWM) load constrains bilingual parallel activation during spoken word comprehension. Hindi-English bilinguals heard a spoken word in Hindi (L1) or English (L2) and saw a display containing the spoken word-referent, a phonological cohort of the spoken word’s translation and two unrelated objects. Participants completed a concurrent WM task of remembering an array of five coloured squares and judging its similarity with a test array. Participants were asked to click on the spoken word-referent in Experiment 1 but not in Experiment 2. Reduced parallel activation and enhanced target activation was observed under the load for L2 spoken words in Experiment 1 (where the task-demands were high). The findings suggest that a VWM load can constrain the spontaneous activation of an irrelevant lexicon, under certain conditions.

Co-activation of Taxonomic and Thematic Relations in Spoken Word Comprehension: Evidence From Eye Movements.

Evidence from behavior, computational linguistics, and neuroscience studies supported that semantic knowledge is represented in (at least) two semantic systems (i.e., taxonomic and thematic systems). It remains unclear whether, and to what extent taxonomic and thematic relations are co-activated. The present study investigated the co-activation of the two types of semantic representations when both types of semantic relations are simultaneously presented. In a visual-world task, participants listened to a spoken target word and looked at a visual display consisted of a taxonomic competitor, a thematic competitor and two distractors. Growth curve analyses revealed that both taxonomic and thematic competitors attracted visual attention during the processing of the target word but taxonomic competitor received more looks than thematic competitor. Moreover, although fixations on taxonomic competitor rose faster than thematic competitor, these two types of competitors started to attract more fixations than distractor in a similar time window. These findings indicate that taxonomic and thematic relations are co-activated by the spoken word, the activation of taxonomic relation is stronger and rise faster than thematic relation.

Regional Brain Dysfunction Associated with Semantic Errors in Comprehension.

Here we illustrate how investigation of individuals acutely after stroke, before structure/function reorganization through recovery or rehabilitation, can be helpful in answering questions about the role of specific brain regions in language functions. Although there is converging evidence from a variety of sources that the left posterior-superior temporal gyrus plays some role in spoken word comprehension, its precise role in this function has not been established. We hypothesized that this region is essential for distinguishing between semantically related words, because it is critical for linking the spoken word to the complete semantic representation. We tested this hypothesis in 127 individuals with 48 hours of acute ischemic stroke, before the opportunity for reorganization or recovery. We identified tissue dysfunction (acute infarct and/or hypoperfusion) in gray and white matter parcels of the left hemisphere, and we evaluated the association between rate of semantic errors in a word-picture verification tasks and extent of tissue dysfunction in each region. We found that after correcting for lesion volume and multiple comparisons, the rate of semantic errors correlated with the extent of tissue dysfunction in left posterior-superior temporal gyrus and retrolenticular white matter.

Grey matter density in the right caudate nucleus predicts aphasic patients’ response to speech comprehension therapy

Grey matter density in the right caudate nucleus predicts aphasic patients’ response to speech comprehension therapy

Understanding environmental sounds in sentence context

There is debate about how individuals use context to successfully predict and recognize words. One view argues that context supports neural predictions that make use of the speech motor system, whereas other views argue for a sensory or conceptual level of prediction. While environmental sounds can convey clear referential meaning, they are not linguistic signals, and are thus neither produced with the vocal tract nor typically encountered in sentence context. We compared the effect of spoken sentence context on recognition and comprehension of spoken words versus nonspeech, environmental sounds. In Experiment 1, sentence context decreased the amount of signal needed for recognition of spoken words and environmental sounds in similar fashion. In Experiment 2, listeners judged sentence meaning in both high and low contextually constraining sentence frames, when the final word was present or replaced with a matching environmental sound. Results showed that sentence constraint affected decision time similarly for speech and nonspeech, such that high constraint sentences (i.e., frame plus completion) were processed faster than low constraint sentences for speech and nonspeech. Linguistic context facilitates the recognition and understanding of nonspeech sounds in much the same way as for spoken words. This argues against a simple form of a speech-motor explanation of predictive coding in spoken language understanding, and suggests support for conceptual-level predictions.

Temporal lobe networks supporting the comprehension of spoken words.

Auditory word comprehension is a cognitive process that involves the transformation of auditory signals into abstract concepts. Traditional lesion-based studies of stroke survivors with aphasia have suggested that neocortical regions adjacent to auditory cortex are primarily responsible for word comprehension. However, recent primary progressive aphasia and normal neurophysiological studies have challenged this concept, suggesting that the left temporal pole is crucial for word comprehension. Due to its vasculature, the temporal pole is not commonly completely lesioned in stroke survivors and this heterogeneity may have prevented its identification in lesion-based studies of auditory comprehension. We aimed to resolve this controversy using a combined voxel-based-and structural connectome-lesion symptom mapping approach, since cortical dysfunction after stroke can arise from cortical damage or from white matter disconnection. Magnetic resonance imaging (T1-weighted and diffusion tensor imaging-based structural connectome), auditory word comprehension and object recognition tests were obtained from 67 chronic left hemisphere stroke survivors. We observed that damage to the inferior temporal gyrus, to the fusiform gyrus and to a white matter network including the left posterior temporal region and its connections to the middle temporal gyrus, inferior temporal gyrus, and cingulate cortex, was associated with word comprehension difficulties after factoring out object recognition. These results suggest that the posterior lateral and inferior temporal regions are crucial for word comprehension, serving as a hub to integrate auditory and conceptual processing. Early processing linking auditory words to concepts is situated in posterior lateral temporal regions, whereas additional and deeper levels of semantic processing likely require more anterior temporal regions.10.1093/brain/awx169_video1awx169media15555638084001.

A task-dependent causal role for low-level visual processes in spoken word comprehension.

It is well established that the comprehension of spoken words referring to object concepts relies on high-level visual areas in the ventral stream that build increasingly abstract representations. It is much less clear whether basic low-level visual representations are also involved. Here we asked in what task situations low-level visual representations contribute functionally to concrete word comprehension using an interference paradigm. We interfered with basic visual processing while participants performed a concreteness task (Experiment 1), a lexical-decision task (Experiment 2), and a word class judgment task (Experiment 3). We found that visual noise interfered more with concrete versus abstract word processing, but only when the task required visual information to be accessed. This suggests that basic visual processes can be causally involved in language comprehension, but that their recruitment is not automatic and rather depends on the type of information that is required in a given task situation. (PsycINFO Database Record

Neural signatures of language co-activation and control in bilingual spoken word comprehension

To examine the neural signatures of language co-activation and control during bilingual spoken word comprehension, Korean-English bilinguals and English monolinguals were asked to make overt or covert semantic relatedness judgments on auditorily-presented English word pairs. In two critical conditions, participants heard word pairs consisting of an English-Korean interlingual homophone (e.g., the sound /mu:n/ means “moon” in English and “door” in Korean) as the prime and an English word as the target. In the homophone-related condition, the target (e.g., “lock”) was related to the homophone’s Korean meaning, but not related to the homophone’s English meaning. In the homophone-unrelated condition, the target was unrelated to either the homophone’s Korean meaning or the homophone’s English meaning. In overtly responded situations, ERP results revealed that the reduced N400 effect in bilinguals for homophone-related word pairs correlated positively with the amount of their daily exposure to Korean. In covertly responded situations, ERP results showed a reduced late positive component for homophone-related word pairs in the right hemisphere, and this late positive effect was related to the neural efficiency of suppressing interference in a non-linguistic task. Together, these findings suggest 1) that the degree of language co-activation in bilingual spoken word comprehension is modulated by the amount of daily exposure to the non-target language; and 2) that bilinguals who are less influenced by cross-language activation may also have greater efficiency in suppressing interference in a non-linguistic task.

Important considerations in lesion-symptom mapping: Illustrations from studies of word comprehension.

Lesion-symptom mapping is an important method of identifying networks of brain regions critical for functions. However, results might be influenced substantially by the imaging modality and timing of assessment. We tested the hypothesis that brain regions found to be associated with acute language deficits depend on (1) timing of behavioral measurement, (2) imaging sequences utilized to define the "lesion" (structural abnormality only or structural plus perfusion abnormality), and (3) power of the study. We studied 191 individuals with acute left hemisphere stroke with MRI and language testing to identify areas critical for spoken word comprehension. We use the data from this study to examine the potential impact of these three variables on lesion-symptom mapping. We found that only the combination of structural and perfusion imaging within 48 h of onset identified areas where more abnormal voxels was associated with more severe acute deficits, after controlling for lesion volume and multiple comparisons. The critical area identified with this methodology was the left posterior superior temporal gyrus, consistent with other methods that have identified an important role of this area in spoken word comprehension. Results have implications for interpretation of other lesion-symptom mapping studies, as well as for understanding areas critical for auditory word comprehension in the healthy brain. We propose that lesion-symptom mapping at the acute stage of stroke addresses a different sort of question about brain-behavior relationships than lesion-symptom mapping at the chronic stage, but that timing of behavioral measurement and imaging modalities should be considered in either case. Hum Brain Mapp 38:2990-3000, 2017. © 2017 Wiley Periodicals, Inc.

Supplemental Material for A Task-Dependent Causal Role for Low-Level Visual Processes in Spoken Word Comprehension

Supplemental Material for A Task-Dependent Causal Role for Low-Level Visual Processes in Spoken Word Comprehension

Causal Influence of Articulatory Motor Cortex on Comprehending Single Spoken Words: TMS Evidence.

Classic wisdom had been that motor and premotor cortex contribute to motor execution but not to higher cognition and language comprehension. In contrast, mounting evidence from neuroimaging, patient research, and transcranial magnetic stimulation (TMS) suggest sensorimotor interaction and, specifically, that the articulatory motor cortex is important for classifying meaningless speech sounds into phonemic categories. However, whether these findings speak to the comprehension issue is unclear, because language comprehension does not require explicit phonemic classification and previous results may therefore relate to factors alien to semantic understanding. We here used the standard psycholinguistic test of spoken word comprehension, the word-to-picture-matching task, and concordant TMS to articulatory motor cortex. TMS pulses were applied to primary motor cortex controlling either the lips or the tongue as subjects heard critical word stimuli starting with bilabial lip-related or alveolar tongue-related stop consonants (e.g., “pool” or “tool”). A significant cross-over interaction showed that articulatory motor cortex stimulation delayed comprehension responses for phonologically incongruent words relative to congruous ones (i.e., lip area TMS delayed “tool” relative to “pool” responses). As local TMS to articulatory motor areas differentially delays the comprehension of phonologically incongruous spoken words, we conclude that motor systems can take a causal role in semantic comprehension and, hence, higher cognition.

Cerebral localization of impaired phonological retrieval during rhyme judgment.

Computation of a prearticulatory phonological representation (phonological access, or phonological retrieval) is an essential process in speech production whose neural localization is not clear. This study combined a specific behavioral measure of phonological access and multivariate voxel-based lesion-symptom mapping (VLSM) in a series of left hemisphere stroke patients to identify brain regions critical for this process. Phonological access was assessed in 40 chronic ischemic stroke patients using a silent rhyming task to avoid confounds with motor planning and articulation deficits. Additional covariates were incorporated in the VLSM analysis to control for orthographic and working memory demands of the rhyming task, and for age, education, and total lesion volume. The resulting t statistic maps were thresholded at voxelwise p < 0.001 and cluster-corrected at a familywise error of p < 0.05. Phonological access impairment was correlated with damage to a focal region of cortex and white matter caudal to the posterior sylvian fissure, which included the posterior supramarginal gyrus and adjacent anterior angular gyrus, planum temporale, and posterior superior temporal gyrus. No correlation was observed with Broca's area, insula, or sensorimotor cortex. An additional VLSM showed no correlation between damage in this posterior perisylvian region and spoken word comprehension. This is the first demonstration of a specific lesion correlate for phonological access impairment. Although this posterior perisylvian region overlaps with some versions of the classical Wernicke area, the present results demonstrate its involvement in prearticulatory phonological production rather than speech perception or lexical-semantic processes.

The interplay between semantic and phonological constraints during spoken-word comprehension.

This study addresses how top-down predictions driven by phonological and semantic information interact on spoken-word comprehension. To do so, we measured event-related potentials to words embedded in sentences that varied in the degree of semantic constraint (high or low) and in regional accent (congruent or incongruent) with respect to the target word pronunciation. The data showed a negative amplitude shift following phonological mismatch (target pronunciation incongruent with respect to sentence regional accent). Here, we show that this shift is modulated by sentence-level semantic constraints over latencies encompassing auditory (N100) and lexical (N400) components. These findings suggest a fast influence of top-down predictions and the interplay with bottom-up processes at sublexical and lexical levels of analysis.

Automatic ultrarapid activation and inhibition of cortical motor systems in spoken word comprehension.

To address the hotly debated question of motor system involvement in language comprehension, we recorded neuromagnetic responses elicited in the human brain by unattended action-related spoken verbs and nouns and scrutinized their timecourse and neuroanatomical substrates. We found that already very early on, from ∼80 ms after disambiguation point when the words could be identified from the available acoustic information, both verbs and nouns produced characteristic somatotopic activations in the motor strip, with words related to different body parts activating the corresponding body representations. Strikingly, along with this category-specific activation, we observed suppression of motor-cortex activation by competitor words with incompatible semantics, documenting operation of the neurophysiological principles of lateral/surround inhibition in neural word processing. The extremely early onset of these activations and deactivations, their emergence in the absence of attention, and their similar presence for words of different lexical classes strongly suggest automatic involvement of motor-specific circuits in the perception of action-related language.