Semantic context effects on color categorization

A number of recent theories of semantic representation propose two-way interaction of semantic and perceptual information. These theories are supported by a growing body of experiments that show widespread interactivity of semantic and perceptual levels of processing. In the current experiment, participants classified ambiguous colors into one of two color categories. The ambiguous colors were presented either as a color patch (no semantic context), as an icon representing an object that is strongly associated with one of the color options, or as a word referring to such an object. Although the iconic and lexical contexts were incidental and irrelevant to the color categorization task, participants' responses were consistently biased toward the context color. These results extend previous findings by showing that lexical contexts, as well as iconic contexts influence color categorization.National Science Foundation (U.S.) (grant F32HD052364)National Science Foundation (U.S.) (Graduate Research Fellowship

Young adults with acquired brain injury show longitudinal improvements in cognition after intensive cognitive rehabilitation

PURPOSE: The aim of this study was to assess the effect of an intensive cognitive and communication rehabilitation (ICCR) program on language and other cognitive performance in young adults with acquired brain injury (ABI). METHOD: Thirty young adults with chronic ABI participated in this study. Treatment participants (n = 22) attended ICCR 6 hours/day, 4 days/week for at least one 12-week semester. Deferred treatment/usual care control participants (n = 14) were evaluated before and after at least one 12-week semester. Pre- and postsemester standardized cognitive assessment items were assigned to subdomains. Between-groups and within-group generalized linear mixed-effects models assessed the effect of time point on overall item accuracy and differences by item subdomain. Subdomain analyses were adjusted for multiple comparisons. RESULTS: Between-groups analyses revealed that treatment participants improved significantly faster over time than deferred treatment/usual care participants in overall item accuracy and specifically on items in the verbal expression subdomain. Investigating the three-way interaction between time point, group, and etiology revealed that the overall effects of the treatment were similar for individuals with nontraumatic and traumatic brain injuries. The treatment group showed an overall effect of treatment and significant gains over time in the verbal expression, written expression, memory, and problem solving subdomains. The control group did not significantly improve over time on overall item accuracy and showed significant subdomain-level gains in auditory comprehension, which did not survive correction. CONCLUSIONS: Sustaining an ABI in young adulthood can significantly disrupt key developmental milestones, such as attending college and launching a career. This study provides strong evidence that integrating impairment-based retraining of language and other cognitive skills with “real-world” application in academically focused activities promotes gains in underlying cognitive processes that are important for academic success as measured by standardized assessment items. These findings may prompt a revision to the current continuum of rehabilitative care for young adults with ABI. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.1932006

Difficulty and pleasure in the comprehension of verb-based metaphor sentences:A behavioral study

What is difficult is not usually pleasurable. Yet, for certain unfamiliar figurative language, like that which is common in poetry, while comprehension is often more difficult than for more conventional language, it is in many cases more pleasurable. Concentrating our investigation on verb-based metaphors, we examined whether and to what degree the novel variations (in the form of verb changes and extensions) of conventional verb metaphors were both more difficult to comprehend and yet induced more pleasure. To test this relationship, we developed a set of 62 familiar metaphor stimuli, each with corresponding optimal and excessive verb variation and metaphor extension conditions, and normed these stimuli using both objective measures and participant subjective ratings. We then tested the pleasure-difficulty relationship with an online behavioral study. Based on Rachel Giora and her colleagues’ ‘optimal innovation hypothesis’, we anticipated an inverse U-shaped relationship between ease and pleasure, with an optimal degree of difficulty, introduced by metaphor variations, producing the highest degree of pleasure when compared to familiar or excessive conditions. Results, however, revealed a more complex picture, with only metaphor extension conditions (not verb variation conditions) producing the anticipated pleasure effects. Individual differences in semantic cognition and verbal reasoning assessed using the Semantic Similarities Test, while clearly influential, further complicated the pleasure-difficulty relationship, suggesting an important avenue for further investigation

Impaired discourse content in aphasia is associated with frontal white matter damage

Aphasia is a common consequence of stroke with severe impacts on employability, social interactions and quality of life. Producing discourse-relevant information in a real-world setting is the most important aspect of recovery because it is critical to successful communication. This study sought to identify the lesion correlates of impaired production of relevant information in spoken discourse in a large, unselected sample of participants with post-stroke aphasia. Spoken discourse (n = 80) and structural brain scans (n = 66) from participants with aphasia following left hemisphere stroke were analysed. Each participant provided 10 samples of spoken discourse elicited in three different genres, and ‘correct information unit’ analysis was used to quantify the informativeness of speech samples. The lesion correlates were identified using multivariate lesion–symptom mapping, voxel-wise disconnection and tract-wise analyses. Amount and speed of relevant information were highly correlated across different genres and with total lesion size. The analyses of lesion correlates converged on the same pattern: impaired production of relevant information was associated with damage to anterior dorsal white matter pathways, specifically the arcuate fasciculus, frontal aslant tract and superior longitudinal fasciculus. Damage to these pathways may be a useful biomarker for impaired informative spoken discourse and informs development of neurorehabilitation strategies

Shared lesion correlates of semantic and letter fluency in post-stroke aphasia

Lesion–symptom mapping studies have reported a temporal versus frontal dissociation between semantic and letter fluency, and mixed evidence regarding the role of white matter. Mass-univariate and multivariate lesion–symptom mapping was used to identify regions associated with semantic and letter fluency deficits in post-stroke aphasia. Multivariate LSM revealed broad networks including underlying white matter, and substantial overlap between both types of fluency, suggesting that semantic fluency and letter fluency largely rely on the same neural system. All data are available on OSF

Representation of event and object concepts in ventral anterior temporal lobe and angular gyrus

Semantic knowledge includes understanding of objects and their features and also understanding of the characteristics of events. The hub-and-spoke theory holds that these conceptual representations rely on multiple information sources that are integrated in a central hub in the ventral anterior temporal lobes. The dual-hub theory expands this framework with the claim that the ventral anterior temporal lobe hub is specialized for object representation, while a second hub in angular gyrus is specialized for event representation. To test these ideas, we used representational similarity analysis, univariate and psychophysiological interaction analyses of fMRI data collected while participants processed object and event concepts (e.g. “an apple,” “a wedding”) presented as images and written words. Representational similarity analysis showed that angular gyrus encoded event concept similarity more than object similarity, although the left angular gyrus also encoded object similarity. Bilateral ventral anterior temporal lobes encoded both object and event concept structure, and left ventral anterior temporal lobe exhibited stronger coding for events. Psychophysiological interaction analysis revealed greater connectivity between left ventral anterior temporal lobe and right pMTG, and between right angular gyrus and bilateral ITG and middle occipital gyrus, for event concepts compared to object concepts. These findings support the specialization of angular gyrus for event semantics, though with some involvement in object coding, but do not support ventral anterior temporal lobe specialization for object concepts

Stroke lesion size:Still a useful biomarker for stroke severity and outcome in times of high-dimensional models

BACKGROUND The volumetric size of a brain lesion is a frequently used stroke biomarker. It stands out among most imaging biomarkers for being a one-dimensional variable that is applicable in simple statistical models. In times of machine learning algorithms, the question arises of whether such a simple variable is still useful, or whether high-dimensional models on spatial lesion information are superior. METHODS We included 753 first-ever anterior circulation ischemic stroke patients (age 68.4±15.2 years; NIHSS at 24 h 4.4±5.1; modified Rankin Scale (mRS) at 3-months median[IQR] 1[0.75;3]) and traced lesions on diffusion-weighted MRI. In an out-of-sample model validation scheme, we predicted stroke severity as measured by NIHSS 24 h and functional stroke outcome as measured by mRS at 3 months either from spatial lesion features or lesion size. RESULTS For stroke severity, the best regression model based on lesion size performed significantly above chance (p < 0.0001) with R2 = 0.322, but models with spatial lesion features performed significantly better with R2 = 0.363 (t(752) = 2.889; p = 0.004). For stroke outcome, the best classification model based on lesion size again performed significantly above chance (p < 0.0001) with an accuracy of 62.8%, which was not different from the best model with spatial lesion features (62.6%, p = 0.80). With smaller training data sets of only 150 or 50 patients, the performance of high-dimensional models with spatial lesion features decreased up to the point of being equivalent or even inferior to models trained on lesion size. The combination of lesion size and spatial lesion features in one model did not improve predictions. CONCLUSIONS Lesion size is a decent biomarker for stroke outcome and severity that is slightly inferior to spatial lesion features but is particularly suited in studies with small samples. When low-dimensional models are desired, lesion size provides a viable proxy biomarker for spatial lesion features, whereas high-precision prediction models in personalised prognostic medicine should operate with high-dimensional spatial imaging features in large samples