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Stimulus degradation adds to working memory load during speech processing. We investigated whether this applies to sign processing and, if so, whether the mechanism implicates secondary auditory cortex. We conducted an fMRI experiment where 16 deaf early signers (DES) and 22 hearing non-signers performed a sign-based n-back task with three load levels and stimuli presented at high and low resolution. We found decreased behavioral performance with increasing load and decreasing visual resolution, but the neurobiological mechanisms involved differed between the two manipulations and did so for both groups. Importantly, while the load manipulation was, as predicted, accompanied by activation in the frontoparietal working memory network, the resolution manipulation resulted in temporal and occipital activation. Furthermore, we found evidence of cross-modal reorganization in the secondary auditory cortex: DES had stronger activation and stronger connectivity between this and several other regions. We conclude that load and stimulus resolution have different neural underpinnings in the visual-verbal domain, which has consequences for current working memory models, and that for DES the secondary auditory cortex is involved in the binding of representations when task demands are low., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Objective: The current update of the Ease of Language Understanding (ELU) model evaluates the predictive and postdictive aspects of speech understanding and communication., Design: The aspects scrutinised concern: (1) Signal distortion and working memory capacity (WMC), (2) WMC and early attention mechanisms, (3) WMC and use of phonological and semantic information, (4) hearing loss, WMC and long-term memory (LTM), (5) WMC and effort, and (6) the ELU model and sign language. Study Samples: Relevant literature based on own or others' data was used., Results: Expectations 1-4 are supported whereas 5-6 are constrained by conceptual issues and empirical data. Further strands of research were addressed, focussing on WMC and contextual use, and on WMC deployment in relation to hearing status. A wider discussion of task demands, concerning, for example, inference-making and priming, is also introduced and related to the overarching ELU functions of prediction and postdiction. Finally, some new concepts and models that have been inspired by the ELU-framework are presented and discussed., Conclusions: The ELU model has been productive in generating empirical predictions/expectations, the majority of which have been confirmed. Nevertheless, new insights and boundary conditions need to be experimentally tested to further shape the model.

Early deafness results in crossmodal reorganization of the superior temporal cortex (STC). Here, we investigated the effect of deafness on cognitive processing. Specifically, we studied the reorganization, due to deafness and sign language (SL) knowledge, of linguistic and nonlinguistic visual working memory (WM). We conducted an fMRI experiment in groups that differed in their hearing status and SL knowledge: deaf native signers, and hearing native signers, hearing nonsigners. Participants performed a 2-back WM task and a control task. Stimuli were signs from British Sign Language (BSL) or moving nonsense objects in the form of point-light displays. We found characteristic WM activations in fronto-parietal regions in all groups. However, deaf participants also recruited bilateral posterior STC during the WM task, independently of the linguistic content of the stimuli, and showed less activation in fronto-parietal regions. Resting-state connectivity analysis showed increased connectivity between frontal regions and STC in deaf compared to hearing individuals. WM for signs did not elicit differential activations, suggesting that SL WM does not rely on modality-specific linguistic processing. These findings suggest that WM networks are reorganized due to early deafness, and that the organization of cognitive networks is shaped by the nature of the sensory inputs available during development.

The perceptual clarity of speech is influenced by more than just the acoustic quality of the sound; it also depends on contextual support. For example, a degraded sentence is perceived to be clearer when the content of the speech signal is provided with matching text (i.e., form-based predictability) before hearing the degraded sentence. Here, we investigate whether sentence-level semantic coherence (i.e., meaning-based predictability), enhances perceptual clarity of degraded sentences, and if so, whether the mechanism is the same as that underlying enhancement by matching text. We also ask whether form- and meaning-based predictability are related to individual differences in cognitive abilities. Twenty participants listened to spoken sentences that were either clear or degraded by noise vocoding and rated the clarity of each item. The sentences had either high or low semantic coherence. Each spoken word was preceded by the homologous printed word (matching text), or by a meaningless letter string (nonmatching text). Cognitive abilities were measured with a working memory test. Results showed that perceptual clarity was significantly enhanced both by matching text and by semantic coherence. Importantly, high coherence enhanced the perceptual clarity of the degraded sentences even when they were preceded by matching text, suggesting that the effects of form- and meaning-based predictions on perceptual clarity are independent and additive. However, when working memory capacity indexed by the Size-Comparison Span Test was controlled for, only form-based predictions enhanced perceptual clarity, and then only at some sound quality levels, suggesting that prediction effects are to a certain extent dependent on cognitive abilities. (PsycINFO Database Record, ((c) 2018 APA, all rights reserved).)

Experimental work has shown better visuospatial working memory (VSWM) in profoundly deaf individuals compared to those with normal hearing. Other data, including the UK Biobank resource shows poorer VSWM in individuals with poorer hearing. Using the same database, the authors investigated VSWM in individuals who reported profound deafness. Included in this study were 112 participants who were profoundly deaf, 1310 with poor hearing and 74,635 with normal hearing. All participants performed a card-pair matching task as a test of VSWM. Although variance in VSWM performance was large among profoundly deaf participants, at group level it was superior to that of participants with both normal and poor hearing. VSWM in adults is related to hearing status but the association is not linear. Future study should investigate the mechanism behind enhanced VSWM in profoundly deaf adults.

Everyday listening may be experienced as effortful, especially by individuals with hearing loss. This may be due to internal factors, such as cognitive load, and external factors, such as noise. Even when speech is audible, internal and external factors may combine to reduce cognitive spare capacity, or the ability to engage in cognitive processing of spoken information. A better understanding of cognitive spare capacity and how it can be optimally allocated may guide new approaches to rehabilitation and ultimately improve outcomes. This article presents results of three tests of cognitive spare capacity:1. Sentence-final Word Identification and Recall (SWIR) test2. Cognitive Spare Capacity Test (CSCT)3. Auditory Inference Span Test (AIST)Results show that noise reduces cognitive spare capacity even when speech intelligibility is retained. In addition, SWIR results show that hearing aid signal processing can increase cognitive spare capacity, and CSCT and AIST results show that increasing load reduces cognitive spare capacity. Correlational evidence suggests that while the effect of noise on cognitive spare capacity is related to working memory capacity, the effect of load is related to executive function. Future studies should continue to investigate how hearing aid signal processing can mitigate the effect of load on cognitive spare capacity, and whether such effects can be enhanced by developing executive skills through training. The mechanisms modulating cognitive spare capacity should be investigated by studying their neural correlates, and tests of cognitive spare capacity should be developed for clinical use in conjunction with developing new approaches to rehabilitation.

Working memory (WM) for spoken language improves when the to-be-remembered items correspond to preexisting representations in long-term memory. We investigated whether this effect generalizes to the visuospatial domain by administering a visual n-back WM task to deaf signers and hearing signers, as well as to hearing nonsigners. Four different kinds of stimuli were presented: British Sign Language (BSL; familiar to the signers), Swedish Sign Language (SSL; unfamiliar), nonsigns, and nonlinguistic manual actions. The hearing signers performed better with BSL than with SSL, demonstrating a facilitatory effect of preexisting semantic representation. The deaf signers also performed better with BSL than with SSL, but only when WM load was high. No effect of preexisting phonological representation was detected. The deaf signers performed better than the hearing nonsigners with all sign-based materials, but this effect did not generalize to nonlinguistic manual actions. We argue that deaf signers, who are highly reliant on visual information for communication, develop expertise in processing sign-based items, even when those items do not have preexisting semantic or phonological representations. Preexisting semantic representation, however, enhances the quality of the gesture-based representations temporarily maintained in WM by this group, thereby releasing WM resources to deal with increased load. Hearing signers, on the other hand, may make strategic use of their speech-based representations for mnemonic purposes. The overall pattern of results is in line with flexible-resource models of WM.

Effects on working memory performance relating to item similarity have been linked to prior categorisation of representations in long-term memory. However, there is evidence from gesture processing that this link may not be obligatory. The present study investigated whether working memory for incidentally generated meaningless manual gestures is influenced by formational similarity and whether this effect is modulated by working-memory load. Results showed that formational similarity did lower performance, demonstrating that similarity effects are not dependent on prior categorisation. However, this effect was only found when working-memory load was low, supporting a flexible resource allocation model according to which it is the quality rather than quantity of working memory representations that determines performance. This interpretation is in line with proposals suggesting language modality specific allocation of resources in working memory., ((PsycINFO Database Record (c) 2015 APA, all rights reserved).)

Objectives: A hearing aid noise reduction (NR) algorithm reduces the adverse effect of competing speech on memory for target speech for individuals with hearing impairment with high working memory capacity. In the present study, we investigated whether the positive effect of NR could be extended to individuals with low working memory capacity, as well as how NR influences recall performance for target native speech when the masker language is non-native., Design: A sentence-final word identification and recall (SWIR) test was administered to 26 experienced hearing aid users. In this test, target spoken native language (Swedish) sentence lists were presented in competing native (Swedish) or foreign (Cantonese) speech with or without binary masking NR algorithm. After each sentence list, free recall of sentence final words was prompted. Working memory capacity was measured using a reading span (RS) test., Results: Recall performance was associated with RS. However, the benefit obtained from NR was not associated with RS. Recall performance was more disrupted by native than foreign speech babble and NR improved recall performance in native but not foreign competing speech., Conclusions: Noise reduction improved memory for speech heard in competing speech for hearing aid users. Memory for native speech was more disrupted by native babble than foreign babble, but the disruptive effect of native speech babble was reduced to that of foreign babble when there was NR.

The present study aimed to investigate the changing relationship between aided speech recognition and cognitive function during the first 6 months of hearing aid use. Twenty-seven first-time hearing aid users with symmetrical mild to moderate sensorineural hearing loss were recruited. Aided speech recognition thresholds in noise were obtained in the hearing aid fitting session as well as at 3 and 6 months postfitting. Cognitive abilities were assessed using a reading span test, which is a measure of working memory capacity, and a cognitive test battery. Results showed a significant correlation between reading span and speech reception threshold during the hearing aid fitting session. This relation was significantly weakened over the first 6 months of hearing aid use. Multiple regression analysis showed that reading span was the main predictor of speech recognition thresholds in noise when hearing aids were first fitted, but that the pure-tone average hearing threshold was the main predictor 6 months later. One way of explaining the results is that working memory capacity plays a more important role in speech recognition in noise initially rather than after 6 months of use. We propose that new hearing aid users engage working memory capacity to recognize unfamiliar processed speech signals because the phonological form of these signals cannot be automatically matched to phonological representations in long-term memory. As familiarization proceeds, the mismatch effect is alleviated, and the engagement of working memory capacity is reduced., (© The Author(s) 2014.)

This study examined how semantically related information facilitates the intelligibility of spoken sentences in the presence of masking sound, and how this facilitation is influenced by masker type and by individual differences in cognitive functioning. Dutch sentences were masked by stationary noise, fluctuating noise, or an interfering talker. Each sentence was preceded by a text cue; cues were either three words that were semantically related to the sentence or three unpronounceable nonwords. Speech reception thresholds were adaptively measured. Additional measures included working memory capacity (reading span and size comparison span), linguistic closure ability (text reception threshold), and delayed sentence recognition. Word cues facilitated speech perception in noise similarly for all masker types. Cue benefit was related to reading span performance when the masker was interfering speech, but not when other maskers were used, and it did not correlate with text reception threshold or size comparison span. Better reading span performance was furthermore associated with enhanced delayed recognition of sentences preceded by word relative to nonword cues, across masker types. The results suggest that working memory capacity is associated with release from informational masking by semantically related information, and additionally with the encoding, storage, or retrieval of speech content in memory.

Purpose: The purpose of the present study was to evaluate the new Cognitive Spare Capacity Test (CSCT), which measures aspects of working memory capacity for heard speech in the audiovisual and auditory-only modalities of presentation., Method: In Experiment 1, 20 young adults with normal hearing performed the CSCT and an independent battery of cognitive tests. In the CSCT, they listened to and recalled 2-digit numbers according to instructions inducing executive processing at 2 different memory loads. In Experiment 2, 10 participants performed a less executively demanding free recall task using the same stimuli., Results: CSCT performance demonstrated an effect of memory load and was associated with independent measures of executive function and inference making but not with general working memory capacity. Audiovisual presentation was associated with lower CSCT scores but higher free recall performance scores., Conclusions: CSCT is an executively challenging test of the ability to process heard speech. It captures cognitive aspects of listening related to sentence comprehension that are quantitatively and qualitatively different from working memory capacity. Visual information provided in the audiovisual modality of presentation can hinder executive processing in working memory of nondegraded speech material.

Neural networks underpinning working memory demonstrate sign language specific components possibly related to differences in temporary storage mechanisms. A processing approach to memory systems suggests that the organisation of memory storage is related to type of memory processing as well. In the present study, we investigated for the first time semantic, phonological and orthographic processing in working memory for sign- and speech-based language. During fMRI we administered a picture-based 2-back working memory task with Semantic, Phonological, Orthographic and Baseline conditions to 11 deaf signers and 20 hearing non-signers. Behavioural data showed poorer and slower performance for both groups in Phonological and Orthographic conditions than in the Semantic condition, in line with depth-of-processing theory. An exclusive masking procedure revealed distinct sign-specific neural networks supporting working memory components at all three levels of processing. The overall pattern of sign-specific activations may reflect a relative intermodality difference in the relationship between phonology and semantics influencing working memory storage and processing., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Unlabelled: Acquired hearing impairment is associated with gradually declining phonological representations. According to the Ease of Language Understanding (ELU) model, poorly defined representations lead to mismatch in phonologically challenging tasks. To resolve the mismatch, reliance on working memory capacity (WMC) increases. This study investigated whether WMC modulated performance in a phonological task in individuals with hearing impairment. A visual rhyme judgment task with congruous or incongruous orthography, followed by an incidental episodic recognition memory task, was used. In participants with hearing impairment, WMC modulated both rhyme judgment performance and recognition memory in the orthographically similar non-rhyming condition; those with high WMC performed exceptionally well in the judgment task, but later recognized few of the words. For participants with hearing impairment and low WMC the pattern was reversed; they performed poorly in the judgment task but later recognized a surprisingly large proportion of the words. Results indicate that good WMC can compensate for the negative impact of auditory deprivation on phonological processing abilities by allowing for efficient use of phonological processing skills. They also suggest that individuals with hearing impairment and low WMC may use a non-phonological approach to written words, which can have the beneficial side effect of improving memory encoding., Learning Outcomes: Readers will be able to: (1) describe cognitive processes involved in rhyme judgment, (2) explain how acquired hearing impairment affects phonological processing and (3) discuss how reading strategies at encoding impact memory performance., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Recently there has been interest in using subjective ratings as a measure of perceived effort during speech recognition in noise. Perceived effort may be an indicator of cognitive load. Thus, subjective effort ratings during speech recognition in noise may covary both with signal-to-noise ratio (SNR) and individual cognitive capacity., Purpose: The present study investigated the relation between subjective ratings of the effort involved in listening to speech in noise, speech recognition performance, and individual working memory (WM) capacity in hearing impaired hearing aid users., Research Design: In two experiments, participants with hearing loss rated perceived effort during aided speech perception in noise. Noise type and SNR were manipulated in both experiments, and in the second experiment hearing aid compression release settings were also manipulated. Speech recognition performance was measured along with WM capacity., Study Sample: There were 46 participants in all with bilateral mild to moderate sloping hearing loss. In Experiment 1 there were 16 native Danish speakers (eight women and eight men) with a mean age of 63.5 yr (SD = 12.1) and average pure tone (PT) threshold of 47. 6 dB (SD = 9.8). In Experiment 2 there were 30 native Swedish speakers (19 women and 11 men) with a mean age of 70 yr (SD = 7.8) and average PT threshold of 45.8 dB (SD = 6.6)., Data Collection and Analysis: A visual analog scale (VAS) was used for effort rating in both experiments. In Experiment 1, effort was rated at individually adapted SNRs while in Experiment 2 it was rated at fixed SNRs. Speech recognition in noise performance was measured using adaptive procedures in both experiments with Dantale II sentences in Experiment 1 and Hagerman sentences in Experiment 2. WM capacity was measured using a letter-monitoring task in Experiment 1 and the reading span task in Experiment 2., Results: In both experiments, there was a strong and significant relation between rated effort and SNR that was independent of individual WM capacity, whereas the relation between rated effort and noise type seemed to be influenced by individual WM capacity. Experiment 2 showed that hearing aid compression setting influenced rated effort., Conclusions: Subjective ratings of the effort involved in speech recognition in noise reflect SNRs, and individual cognitive capacity seems to influence relative rating of noise type., (American Academy of Audiology.)

Purpose: To test the relationship between degree of hearing loss and different memory systems in hearing aid users., Method: Structural equation modeling (SEM) was used to study the relationship between auditory and visual acuity and different cognitive and memory functions in an age-hetereogenous subsample of 160 hearing aid users without dementia, drawn from the Swedish prospective cohort aging study known as Betula (L.-G. Nilsson et al., 1997)., Results: Hearing loss was selectively and negatively related to episodic and semantic long-term memory (LTM) but not short-term memory (STM) performance. This held true for both ears, even when age was accounted for. Visual acuity alone, or in combination with auditory acuity, did not contribute to any acceptable SEM solution., Conclusions: The overall relationships between hearing loss and memory systems were predicted by the ease of language understanding model (J. Rönnberg, 2003), but the exact mechanisms of episodic memory decline in hearing aid users (i.e., mismatch/disuse, attentional resources, or information degradation) remain open for further experiments. The hearing aid industry should strive to design signal processing algorithms that are cognition friendly.

Background: Previous studies have demonstrated a relation between cognitive capacity, in particular working memory, and the ability to understand speech in noise with different types of hearing aid signal processing., Purpose: The present study investigates the relation between working memory capacity and the speech recognition performance of persons with hearing impairment under both aided and unaided conditions, following a period of familiarization to both fast- and slow-acting compression settings in the participants' own hearing aids., Research Design: Speech recognition was tested in modulated and steady state noise with fast and slow compression release settings (for aided conditions) with each of two materials. Working memory capacity was also measured., Study Sample: Thirty experienced hearing aid users with a mean age of 70 yr (SD = 7.8) and pure-tone average hearing threshold across the frequencies 0.25, 0.5, 1, 2, 3, 4, and 6 kHz (PTA7) and for both ears of 45.8 dB HL (SD = 6.6., Intervention: 9 wk experience with each of fast-acting and slow-acting compression., Data Collection and Analysis: Speech recognition data were analyzed using repeated measures analysis of variance with the within-subjects factors of material (high constraint, low constraint), noise type (steady state, modulated), and compression (fast, slow), and the between-subjects factor working memory capacity (high, low)., Results: With high constraint material, there were three-way interactions including noise type and working memory as well as compression, in aided conditions, and performance level, in unaided conditions, but no effects of either working memory or compression with low constraint material. Investigation of simple main effects showed a significant effect of working memory during speech recognition under conditions of both "high degradation" (modulated noise, fast-acting compression, low signal-to-noise ratio [SNR]) and "low degradation" (steady state noise, slow-acting compression, high SNR). The finding of superior performance of persons with high working memory capacity in modulated noise with fast-acting compression agrees with findings of previous studies including a familiarization period of at least 9 wk, in contrast to studies with familiarization of 4 wk or less that have shown that persons with lower cognitive capacity may benefit from slow-acting compression., Conclusions: Working memory is a crucial factor in speech understanding in noise for persons with hearing impairment, irrespective of whether hearing is aided or unaided. Working memory supports speech understanding in noise under conditions of both "high degradation" and "low degradation." A subcomponent view of working memory may contribute to our understanding of these phenomena. The effect of cognition on speech understanding in modulated noise with fast-acting compression may only pertain after a period of 4-9 wk of familiarization and that prior to such a period, persons with lower cognitive capacity may benefit more from slow-acting compression., (American Academy of Audiology.)

Perceptual load and cognitive load can be separately manipulated and dissociated in their effects on speech understanding in noise. The Ease of Language Understanding model assumes a theoretical position where perceptual task characteristics interact with the individual's implicit capacities to extract the phonological elements of speech. Phonological precision and speed of lexical access are important determinants for listening in adverse conditions. If there are mismatches between the phonological elements perceived and phonological representations in long-term memory, explicit working memory (WM)-related capacities will be continually invoked to reconstruct and infer the contents of the ongoing discourse. Whether this induces a high cognitive load or not will in turn depend on the individual's storage and processing capacities in WM. Data suggest that modulated noise maskers may serve as triggers for speech maskers and therefore induce a WM, explicit mode of processing. Individuals with high WM capacity benefit more than low WM-capacity individuals from fast amplitude compression at low or negative input speech-to-noise ratios. The general conclusion is that there is an overarching interaction between the focal purpose of processing in the primary listening task and the extent to which a secondary, distracting task taps into these processes.

Deaf native signers have a general working memory (WM) capacity similar to that of hearing non-signers but are less sensitive to the temporal order of stored items at retrieval. General WM capacity declines with age, but little is known of how cognitive aging affects WM function in deaf signers. We investigated WM function in elderly deaf signers (EDS) and an age-matched comparison group of hearing non-signers (EHN) using a paradigm designed to highlight differences in temporal and spatial processing of item and order information. EDS performed worse than EHN on both item and order recognition using a temporal style of presentation. Reanalysis together with earlier data showed that with the temporal style of presentation, order recognition performance for EDS was also lower than for young adult deaf signers. Older participants responded more slowly than younger participants. These findings suggest that apart from age-related slowing irrespective of sensory and language status, there is an age-related difference specific to deaf signers in the ability to retain order information in WM when temporal processing demands are high. This may be due to neural reorganisation arising from sign language use. Concurrent spatial information with the Mixed style of presentation resulted in enhanced order processing for all groups, suggesting that concurrent temporal and spatial cues may enhance learning for both deaf and hearing groups. These findings support and extend the WM model for Ease of Language Understanding.

The working memory model for Ease of Language Understanding (ELU) proposes that language understanding under taxing conditions is related to explicit cognitive capacity. We refer to this as the mismatch hypothesis, since phonological representations based on the processing of speech under established conditions may not be accessed so readily when input conditions change and a match becomes problematic. Then, cognitive capacity requirements may differ from those used for processing speech hitherto. In the present study, we tested this hypothesis by investigating the relationship between aided speech recognition in noise and cognitive capacity in experienced hearing aid users when there was either a match or mismatch between processed speech input and established phonological representations. The settings in the existing digital hearing aids of the participants were adjusted to one of two different compression settings which processed the speech signal in qualitatively different ways ("fast" or "slow"). Testing took place after a 9-week period of experience with the new setting. Speech recognition was tested under different noise conditions and with match or mismatch (i.e. alternative compression setting) manipulations of the input signal. Individual cognitive capacity was measured using a reading span test and a letter monitoring test. Reading span, a reliable measure of explicit cognitive capacity, predicted speech recognition performance under mismatch conditions when processed input was incongruent with recently established phonological representations, due to the specific hearing aid setting. Cognitive measures were not main predictors of performance under match conditions. These findings are in line with the ELU model.

Working memory (WM) for sign language has an architecture similar to that for speech-based languages at both functional and neural levels. However, there are some processing differences between language modalities that are not yet fully explained, although a number of hypotheses have been mooted. This article reviews some of the literature on differences in sensory, perceptual and cognitive processing systems induced by auditory deprivation and sign language use and discusses how these differences may contribute to differences in WM architecture for signed and speech-based languages. In conclusion, it is suggested that left-hemisphere reorganization of the motion-processing system as a result of native sign-language use may interfere with the development of the order processing system in WM.

A body of work has accumulated to show that the cognitive process of binding information from different mnemonic and sensory sources as well as in different linguistic modalities can be fractionated from general executive functions in working memory both functionally and neurally. This process has been defined in terms of the episodic buffer (Baddeley in Trends Cogn Sci 4(11):417-423, 2000). This paper considers behavioural, neuropsychological and neuroimaging data that elucidate the role of the episodic buffer in language processing. We argue that the episodic buffer seems to be truly multimodal in function and that while formation of unitary multidimensional representations in the episodic buffer seems to engage posterior neural networks, maintenance of such representations is supported by frontal networks. Although, the episodic buffer is not necessarily supported by executive processes and seems to be supported by different neural networks, it may operate in tandem with the central executive during effortful language processing. There is also evidence to suggest engagement of the phonological loop during buffer processing. The hippocampus seems to play a role in formation but not maintenance of representations in the episodic buffer of working memory.

The episodic buffer accommodates formation and maintenance of unitary multidimensional representations based on information in different codes from different sources. Formation, based on submorphemic units, engages posterior brain regions, while maintenance engages frontal regions. Using a hybrid fMRI design, that allows separate analysis of transient and sustained components, an n-back task and an experimental group of 13 hearing native signers, with experience of Swedish Sign Language and Swedish since birth, we investigated binding of lexical signs and words in working memory. Results show that the transient component of these functions is supported by a buffer-specific network of posterior regions including the right middle temporal lobe, possibly relating to binding of phonological loop representations with semantic representations in long-term memory, as well as a loop-specific network, in line with predictions of a functional relationship between loop and buffer. The left hippocampus was engaged in transient and sustained components of buffer processing, possibly reflecting the meaningful nature of the stimuli. Only a minor role was found for executive functions in line with other recent work. A novel representation of the sustained component of working memory for audiovisual language in the right inferior temporal lobe may be related to perception of speech-related facial gestures. Previous findings of sign and speech loop representation in working memory were replicated and extended. Together, these findings support the notion of a module that mediates between codes and sources, such as the episodic buffer, and further our understanding of its nature.

Eight, early bilingual, sign language interpreters participated in a PET study, which compared working memory for Swedish Sign Language (SSL) with working memory for audiovisual Swedish speech. The interaction between language modality and memory task was manipulated in a within-subjects design. Overall, the results show a previously undocumented, language modality-specific working memory neural architecture for SSL, which relies on a network of bilateral temporal, bilateral parietal and left premotor activation. In addition, differential activation in the right cerebellum was found for the two language modalities. Similarities across language modality are found in Broca's area for all tasks and in the anterior left inferior frontal lobe for semantic retrieval. The bilateral parietal activation pattern for sign language bears similarity to neural activity during, e.g., nonverbal visuospatial tasks, and it is argued that this may reflect generation of a virtual spatial array. Aspects of the data suggesting an age of acquisition effect are also considered. Furthermore, it is discussed why the pattern of parietal activation cannot be explained by factors relating to perception, production or recoding of signs, or to task difficulty. The results are generally compatible with Wilson's [Psychon. Bull. Rev. 8 (2001) 44] account of working memory.