Speakers show syntactic priming – that is, a tendency to repeat syntactic constructions they have recently comprehended or produced – and this tendency is even stronger when adjacent utterances share ...the same main verb, termed the lexical boost. Some have suggested that abstract syntactic priming (i.e., with no lexical overlap) derives from implicit learning, whereas the lexical boost derives from explicit short-term memory (STM) for the prime (e.g., Chang, Dell, & Bock, 2006). To address this issue, we assessed twelve people with aphasia (PWA) with varying degrees of STM and language deficits and eleven age-matched healthy control speakers in a syntactic priming experiment. Despite the PWA's difficulty in maintaining phonological, semantic, and structural information, as evidenced by various STM and sentence repetition measures, they showed lexical boost effects comparable to those of healthy speakers. Moreover, the size of the lexical boost was unrelated to the degree of STM deficit, suggesting that the lexical boost does not rely on explicit memory. Alternative explanations for the differing patterns for syntactic priming with and without lexical overlap are discussed.
•People with aphasia (PWA) showed syntactic priming and a lexical boost.•The lexical boost effects in PWA were comparable to those of healthy control speakers.•The lexical boost effects in PWA were unrelated to their degree of short-term memory deficits.•The lexical boost does not depend on explicit short-term memory.
Some early studies of people with aphasia reported strikingly better performance on lexical than on sublexical speech perception tasks. These findings challenged the claim that lexical processing ...depends on sublexical processing and suggested that acoustic information could be mapped directly to lexical representations. However, Dial and Martin (Neuropsychologia 96: 192-212, 2017) argued that these studies failed to match the discriminability of targets and distractors for the sublexical and lexical stimuli and showed that when using closely matched tasks with natural speech tokens, no patient performed substantially better at the lexical than at the sublexical processing task. In the current study, we sought to provide converging evidence for the dependence of lexical on sublexical processing by examining the perception of synthetic speech stimuli varied on a voice-onset time continuum using eye-tracking methodology, which is sensitive to online speech perception processes. Eight individuals with aphasia and ten age-matched controls completed two visual world paradigm tasks: phoneme (sublexical) and word (lexical) identification. For both identification and eye-movement data, strong correlations were observed between the sublexical and lexical tasks. Critically, no patient within the control range on the lexical task was impaired on the sublexical task. Overall, the current study supports the claim that lexical processing depends on sublexical processing. Implications for inferring deficits in people with aphasia and the use of sublexical tasks to assess sublexical processing are also discussed.
Prior evidence suggests domain-specific working memory (WM) buffers for maintaining phonological (i.e., speech sound) and semantic (i.e., meaning) information. The phonological WM buffer's proposed ...location is in the left supramarginal gyrus (SMG), whereas semantic WM has been related to the left inferior frontal gyrus (IFG), the middle frontal gyrus (MFG), and the angular gyrus (AG). However, less is known about the white matter correlates of phonological and semantic WM. We tested 45 individuals with left hemisphere brain damage on single word processing, phonological WM, and semantic WM tasks and obtained T1 and diffusion weighted neuroimaging. Virtual dissections were performed for each participants' arcuate fasciculus (AF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), middle longitudinal fasciculus (MLF), and uncinate fasciculus (UF), which connect the proposed domain-specific WM buffers with perceptual or processing regions. The results showed that the left ILF, MLF, IFOF, and the direct segment of the AF were related to semantic WM performance. Phonological WM was related to both the left ILF and the MLF. This work informs our understanding of the white matter correlates of WM, especially semantic WM, which has not previously been investigated. In addition, this work helps to adjudicate between theories of verbal WM, providing some evidence for separate pathways supporting phonological and semantic WM.
Earlier formulations of the relation of language and the brain provided oversimplified accounts of the nature of language disorders, classifying patients into syndromes characterized by the ...disruption of sensory or motor word representations or by the disruption of syntax or semantics. More recent neuropsychological findings, drawn mainly from case studies, provide evidence regarding the various levels of representations and processes involved in single-word and sentence processing. Lesion data and neuroimaging findings are converging to some extent in providing localization of these components of language processing, particularly at the single-word level. Much work remains to be done in developing precise theoretical accounts of sentence processing that can accommodate the observed patterns of breakdown. Such theoretical developments may provide a means of accommodating the seemingly contradictory findings regarding the neural organization of sentence processing.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study investigated the nature of the underlying working memory system supporting sentence processing through examining individual differences in sensitivity to retrieval interference effects ...during sentence comprehension. Interference effects occur when readers incorrectly retrieve sentence constituents which are similar to those required during integrative processes. We examined interference arising from a partial match between distracting constituents and syntactic and semantic cues, and related these interference effects to performance on working memory, short-term memory (STM), vocabulary, and executive function tasks. For online sentence comprehension, as measured by self-paced reading, the magnitude of individuals' syntactic interference effects was predicted by general WM capacity and the relation remained significant when partialling out vocabulary, indicating that the effects were not due to verbal knowledge. For offline sentence comprehension, as measured by responses to comprehension questions, both general WM capacity and vocabulary knowledge interacted with semantic interference for comprehension accuracy, suggesting that both general WM capacity and the quality of semantic representations played a role in determining how well interference was resolved offline. For comprehension question reaction times, a measure of semantic STM capacity interacted with semantic but not syntactic interference. However, a measure of phonological capacity (digit span) and a general measure of resistance to response interference (Stroop effect) did not predict individuals' interference resolution abilities in either online or offline sentence comprehension. The results are discussed in relation to the multiple capacities account of working memory (e.g., Martin and Romani, 1994; Martin and He, 2004), and the cue-based retrieval parsing approach (e.g., Lewis et al., 2006; Van Dyke et al., 2014). While neither approach was fully supported, a possible means of reconciling the two approaches and directions for future research are proposed.
•Greater fMRI activity was observed in the left than the right STG during a sublexical speech perception task.•TMS disrupted performance during a speech perception task when applied to the left ...anterior STG relative to a control region.•TMS on the left posterior STG and the right STG during a speech perception task did not significantly disrupt performance.•A causal role of the left anterior STG on speech perception was established but not of the right STG.
Debate continues regarding the necessary role of right superior temporal gyrus (STG) regions in sublexical speech perception given the bilateral STG activation often observed in fMRI studies. To evaluate the causal roles, TMS pulses were delivered to inhibit and disrupt neuronal activity at the left and right STG regions during a nonword discrimination task based on peak activations from a blocked fMRI paradigm assessing speech vs. nonspeech perception (N = 20). Relative to a control region located in the posterior occipital lobe, TMS to the left anterior STG (laSTG) led to significantly worse accuracy, whereas TMS to the left posterior STG (lpSTG) and right anterior STG (raSTG) did not. Although the disruption from TMS was significantly greater for the laSTG than for raSTG, the difference in accuracy between the laSTG and lpSTG did not reach significance. The results argue for a causal role of the laSTG but not raSTG in speech perception. Further research is needed to establish the source of the differences between the laSTG and lpSTG.
Two individual differences experiments examined the relationship between executive control and the revision of misinterpretations in sentence comprehension. Garden-path sentences were used as they ...often lead to initial misinterpretations, necessitating revision during comprehension. In addition to garden-path revision, verbal and non-verbal executive controls were assessed by using the verbal and non-verbal version of the Stroop task. Experiment 1 showed that garden-path revision errors in a grammaticality judgement task correlated with verbal Stroop interference errors. Experiment 2 further showed that the time taken to revise the garden-path interpretation correlated with the time taken to resolve verbal Stroop interference, but not with the time taken to resolve non-verbal Stroop interference. Together, the results argue for a role of executive control, which is possibly domain-specific, in the revision of misinterpretations during sentence comprehension.
This study investigates concreteness effects in tasks requiring short-term retention. Concreteness effects were assessed in serial recall, matching span, order reconstruction, and free recall. Each ...task was carried out both in a control condition and under articulatory suppression. Our results show no dissociation between tasks that do and do not require spoken output. This argues against the redintegration hypothesis according to which lexical-semantic effects in short-term memory arise only at the point of production. In contrast, concreteness effects were modulated by task demands that stressed retention of item versus order information. Concreteness effects were stronger in free recall than in serial recall. Suppression, which weakens phonological representations, enhanced the concreteness effect with item scoring. In a matching task, positive effects of concreteness occurred with open sets but not with closed sets of words. Finally, concreteness effects reversed when the task asked only for recall of word positions (as in the matching task), when phonological representations were weak (because of suppression), and when lexical semantic representations overactivated (because of closed sets). We interpret these results as consistent with a model where phonological representations are crucial for the retention of order, while lexical-semantic representations support maintenance of item identity in both input and output buffers.
In cognitive network neuroscience, the connectivity and community structure of the brain network is related to measures of cognitive performance, like attention and memory. Research in this emerging ...discipline has largely focused on two measures of connectivity-modularity and flexibility-which, for the most part, have been examined in isolation. The current project investigates the relationship between these two measures of connectivity and how they make separable contribution to predicting individual differences in performance on cognitive tasks. Using resting state fMRI data from 52 young adults, we show that flexibility and modularity are highly negatively correlated. We use a Brodmann parcellation of the fMRI data and a sliding window approach for calculation of the flexibility. We also demonstrate that flexibility and modularity make unique contributions to explain task performance, with a clear result showing that modularity, not flexibility, predicts performance for simple tasks and that flexibility plays a greater role in predicting performance on complex tasks that require cognitive control and executive functioning. The theory and results presented here allow for stronger links between measures of brain network connectivity and cognitive processes.
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