Automaticity of phonological and semantic processing during visual word recognition

Reading reshapes stimulus selectivity in the visual word form area

Reading depends on a brain region known as the "visual word form area" (VWFA) in left ventral occipito-temporal cortex. This region's function is debated because its stimulus selectivity is not absolute, it is modulated by a variety of task demands, and it is inconsistently localized. We used fMRI to characterize the combination of sensory and cognitive factors that activate word-responsive regions that we precisely localized in 16 adult humans (4 male). We then presented three types of character strings: English words, pseudowords, and unfamiliar characters with matched visual features. Participants performed three different tasks while viewing those stimuli: detecting real words, detecting color in the characters, and detecting color in the fixation mark. There were three primary findings about the VWFA's response: (1) It preferred letter strings over unfamiliar characters even when the stimuli were ignored during the fixation task; (2) Compared to those baseline responses, engaging in the word reading task enhanced the response to words but suppressed the response to unfamiliar characters. (3) Attending to the stimuli to judge their font color had little effect on the response magnitudes. Thus, the VWFA is uniquely modulated by a cognitive signal that is specific to voluntary linguistic processing and is not additive. Functional connectivity analyses revealed that communication between the VWFA and a left frontal language area increased when the participant engaged in the linguistic task. We conclude that the VWFA is inherently selective for familiar orthography, but it falls under control of the language network when the task demands it.

Distinct parallel activation and interaction between dorsal and ventral pathways during phonological and semantic processing: A cTBS-fMRI study

Successful visual word recognition requires the integration of phonological and semantic information, which is supported by the dorsal and ventral pathways in the brain. However, the functional specialization or interaction of these pathways during phonological and semantic processing remains unclear. Previous research has been limited by its dependence on correlational functional magnetic resonance imaging (fMRI) results or causal validation using patient populations, which are susceptible to confounds such as plasticity and lesion characteristics. To address this, the present study employed continuous theta-burst stimulation combined with fMRI in a within-subject design to assess rapid adaptation in regional activity and functional connectivity of the dorsal and ventral pathways during phonological and semantic tasks. This assessment followed the precise inhibition of the left inferior parietal lobule and anterior temporal lobe in the dorsal and ventral pathways, respectively. Our results reveal that both the dorsal and ventral pathways were activated during phonological and semantic processing, while the adaptation activation and interactive network were modulated by the task type and inhibited region. The two pathways exhibited interconnectivity in phonological processing, and disruption of either pathway led to rapid adaptation across both pathways. In contrast, only the ventral pathway exhibited connectivity in semantic processing, and disruption of this pathway alone resulted in adaptive effects primarily in the ventral pathway. These findings provide essential evidence supporting the interactive theory, phonological information processing in particular, potentially providing meaningful implications for clinical populations.

No conclusive evidence for number-induced attentional shifts in a temporal order judgement task

The Spatial Numerical Association of Response Codes (SNARC) effect refers to the observation that relatively small (e.g., 1) and large numbers (e.g., 9) elicit faster left- and right-sided manual responses, respectively. In a variation known as the attentional SNARC effect, merely looking at numbers caused a left- or right-ward shift in covert spatial attention, depending on the number's magnitude. In our study, we probed the notion that numbers induce shifts of spatial attention in accordance with their position on a mental number line (MNL). Critically, we removed any putative spatial response code that may contaminate the responses. We used a square and a tilted square as targets, thereby situating the decisive response dimension in the ventral, non-spatial processing stream. In two experiments where numbers were used as non-informative cues preceding a temporal order judgement (TOJ) task, we did not observe a deflection of the locus of spatial attention as a function of the numerical magnitude of the cue. In a third experiment, finding a significant modulation of TOJ performance as a function of the pointing direction of arrow cues allowed us to rule out the possibility that the absence of any significant modulation in Experiments 1 and 2 was due to a lack of sensitivity of our task set-up. We conclude from the current findings that the spatial codes that the perception and naming of numbers potentially elicit are not in and by themselves sufficient to elicit deflections of spatial attention.

Differential working memory function between phonological and visuospatial strategies: a magnetoencephalography study using a same visual task

Previous studies have reported that, in working memory, the processing of visuospatial information and phonological information have different neural bases. However, in these studies, memory items were presented via different modalities. Therefore, the modality in which the memory items were presented and the strategy for memorizing them were not rigorously distinguished. In the present study, we explored the neural basis of two working memory strategies. Nineteen right-handed young adults memorized seven sequential directions presented visually in a task in which the memory strategy was either visuospatial or phonological (visuospatial/phonological condition). Source amplitudes of theta-band (5-7 Hz) rhythm were estimated from magnetoencephalography during the maintenance period and further analyzed using cluster-based permutation tests. Behavioral results revealed that the accuracy rates showed no significant differences between conditions, while the reaction time in the phonological condition was significantly longer than that in the visuospatial condition. Theta activity in the phonological condition was significantly greater than that in the visuospatial condition, and the cluster in spatio-temporal matrix with p < 5% difference extended to right prefrontal regions in the early maintenance period and right occipito-parietal regions in the late maintenance period. The theta activity results did not indicate strategy-specific neural bases but did reveal the dynamics of executive function required for phonological processing. The functions seemed to move from attention control and inhibition control in the prefrontal region to inhibition of irrelevant information in the occipito-parietal region.

Ongoing Sign Processing Facilitates Written Word Recognition in Deaf Native Signing Children

Signed and written languages are intimately related in proficient signing readers. Here, we tested whether deaf native signing beginning readers are able to make rapid use of ongoing sign language to facilitate recognition of written words. Deaf native signing children (mean 10 years, 7 months) received prime target pairs with sign word onsets as primes and written words as targets. In a control group of hearing children (matched in their reading abilities to the deaf children, mean 8 years, 8 months), spoken word onsets were instead used as primes. Targets (written German words) either were completions of the German signs or of the spoken word onsets. Task of the participants was to decide whether the target word was a possible German word. Sign onsets facilitated processing of written targets in deaf children similarly to spoken word onsets facilitating processing of written targets in hearing children. In both groups, priming elicited similar effects in the simultaneously recorded event related potentials (ERPs), starting as early as 200 ms after the onset of the written target. These results suggest that beginning readers can use ongoing lexical processing in their native language - be it signed or spoken - to facilitate written word recognition. We conclude that intimate interactions between sign and written language might in turn facilitate reading acquisition in deaf beginning readers.

Reading abilities and dopamine D2/D3 receptor availability: An inverted U-shaped association in subjects with schizophrenia

Reading impairments are prominent trait-like features of cognitive deficits in schizophrenia, predictive of overall cognitive functioning and presumably linked to dopaminergic abnormalities. To evaluate this, we used ¹⁸F-fallypride PET in 19 healthy and 21 antipsychotic-naïve schizophrenia subjects and correlated dopamine receptor binding potentials in relevant AFNI-derived regions and voxelwise with group performance on WRAT4 single-word reading subtest. Healthy subjects' scores were positively and linearly associated with D₂/D₃ receptor availability in the rectus, orbital and superior frontal gyri, fusiform and middle temporal gyri, as well as middle occipital gyrus and precuneus, all predominantly in the left hemisphere and previously implicated in reading, hence suggesting that higher dopamine receptor density is cognitively advantageous. This relationship was weakened in schizophrenia subjects and in contrast to healthy participants followed an inverted U-shaped curve both in the cortex and dorsal striatum, indicating restricted optimal range of dopamine D₂/D₃ receptor availability for cognitive performance in schizophrenia.

How semantic knowledge enhances word recognition? New evidence from struggling readers performances

The current study examined the contribution of semantic knowledge to the process of reading aloud unfamiliar words among thirty non-typical readers from third grade. The performances of reading aloud were tested by using three lists of pseudowords: semantic, phonological, and un-trained. For each pseudoword in the list of semantic condition, an invented meaning was matched, and the participants orally trained to learn such invented meaning. For the list of the phonological condition, the participants were orally taught the pronunciation of the pseudowords only, while the third list of pseudowords was not trained at all. After the training phase, the subjects were examined by reading aloud the pseudowords which were presented randomly. For all lists of the pseudowords, there was no orthographic exposure before the reading trial. The findings showed that the higher levels of accuracy were significantly recorded for the semantic condition as compared to the other conditions, without a significant difference in the reading rate between all the conditions. The current findings were discussed in the context of the contribution of semantic activation to reading aloud of written words.

Unconscious preparation: Effects of prime visibility on semantic generalization of task priming

Studies found that subliminal primes can be associated with specific tasks to facilitate task performance, and such learning is highly adaptive and generalizable. Meanwhile, conditioning studies suggest that aversive/reward learning and generalization actually occur at the semantic level. The current study shows that prime-task associations can also be generalized to novel word/neighbour primes from the same semantic category, and this occurs without contingency awareness. Previous studies have counterintuitively suggested that both the learning of task priming and the semantic priming of word neighbours depend on the lack of visibility. Here, we show that semantic generalization indeed depends on reduced visibility, but cannot occur subliminally. The current study shows for the first time that semantic learning and generalization can occur without any emotional or motivational factors, and that semantic priming can occur for arbitrary-linked stimuli in a context completely devoid of semantics.

Automaticity in the reading circuitry

Skilled reading requires years of practice associating visual symbols with speech sounds. Over the course of the learning process, this association becomes effortless and automatic. Here we test whether automatic activation of spoken-language circuits in response to visual words is a hallmark of skilled reading. Magnetoencephalography was used to measure word-selective responses under multiple cognitive tasks (N = 42, 7-12 years of age). Even when attention was drawn away from the words by performing an attention-demanding fixation task, strong word-selective responses were found in a language region (i.e., superior temporal gyrus) starting at ~300 ms after stimulus onset. Critically, this automatic word-selective response was indicative of reading skill: the magnitude of word-selective responses correlated with individual reading skill. Our results suggest that automatic recruitment of spoken-language circuits is a hallmark of skilled reading; with practice, reading becomes effortless as the brain learns to automatically translate letters into sounds and meaning.

How does inattention affect written and spoken language processing?

The classic cocktail party effect suggests that some, but probably not all levels of language processing can proceed without attention. We used whole-brain functional MRI to investigate how modality-specific and modality-independent language areas are modulated by the withdrawal of attention to another sensory modality (e.g., attending to vision during the presentation of auditory sentences, or vice-versa). We tested the hypotheses that inattention may abolish sentence-level integration and eliminate top-down effects. In both written and spoken modalities, language processing was strongly modulated by the distraction of attention, but this inattention effect varied considerably depending on the area and hierarchical level of language processing. Under inattention, a bottom-up activation remained in early modality-specific areas, particularly in superior temporal spoken-language areas, but the difference between sentences and words lists vanished. Under both attended and unattended conditions, ventral temporal cortices were activated in a top-down manner by spoken language more than by control stimuli, reaching posteriorily the Visual Word Form Area. We conclude that inattention prevents sentence-level syntactic and semantic integration, but preserves some top-down crossmodal processing, plus a large degree of bottom-up modality-specific processing, including a ventral occipito-temporal specialization for letter strings in a known alphabet.

Activation time-course of phonological code in silent word recognition in adult readers with and without dyslexia

In skilled adult readers, reading words is generally assumed to rapidly and automatically activate the phonological code. In adults with dyslexia, despite the main consensus on their phonological processing deficits, little is known about the activation time course of this code. The present study investigated this issue in both populations. Participants' accuracy and eye movements were recorded while they performed a visual lexical decision task in which phonological consistency of written words was manipulated. Readers with dyslexia were affected by phonological consistency during second fixation duration of visual word recognition suggesting a late activation of the phonological code. Regarding skilled readers, no influence of phonological consistency was found when the participants were considered a homogeneous population. However, a different pattern emerged when they were divided into two subgroups according to their phonological and semantic abilities: Those who showed better decoding than semantic skills were affected by phonological consistency at the earliest stage of visual word recognition while those who showed better semantic than decoding skills were not affected by this factor at any processing stage. Overall, the findings suggest that the presence of phonological deficits in readers with dyslexia is associated with a delayed activation of phonological representations during reading. In skilled readers, the contribution of phonology varies with their reading profile, i.e., being phonologically or semantically oriented.

Orthographic, Phonological, and Semantic Dynamics During Visual Word Recognition in Deaf Versus Hearing Adults

Purpose Studies on reading in individuals with severe-to-profound hearing loss (deaf) raise the possibility that, due to deficient phonological coding, deaf individuals may rely more on orthographic-semantic links than on orthographic-phonological links. However, the relative contribution of phonological and semantic information to visual word recognition in deaf individuals was not directly assessed in these studies. The aim of the present study, therefore, was to examine the interplay between orthographic, phonological, and semantic representations during visual word recognition, in deaf versus hearing adults. Method Deaf and hearing participants were asked to perform a visual lexical decision task in Hebrew. The critical stimuli consisted of three types of Hebrew words, which differ in terms of their relationship between orthography, phonology, and semantics: unambiguous words, homonyms, and homographs. Results In the hearing group, phonological effects were more pronounced than semantic effects: Homographs (multiple pronunciations) were recognized significantly slower than homonyms or unambiguous words (one pronunciation). However, there was no significant difference between homonyms (multiple meanings) and unambiguous words (one meaning). In contrast, in the deaf group, there was no significant difference among the three word types, indicating that visual word recognition, in these participants, is driven primarily by orthography. Conclusion While visual word recognition in hearing readers is accomplished mainly via orthographic-phonological connections, deaf readers rely mainly on orthographic-semantic connections.

Automatic Detection of Cognitive Impairments through Acoustic Analysis of Speech

Background: Early detection of mild cognitive impairment is crucial in the prevention of Alzheimer’s disease. The aim of the present study was to identify whether acoustic features can help differentiate older, independent community-dwelling individuals with cognitive impairment from healthy controls.

Methods: A total of 8779 participants (mean age 74.2 ± 5.7 in the range of 65-96, 3907 males and 4872 females) with different cognitive profiles, namely healthy controls, mild cognitive impairment, global cognitive impairment (defined as a Mini Mental State Examination score of 20-23), and mild cognitive impairment with global cognitive impairment (a combined status of mild cognitive impairment and global cognitive impairment), were evaluated in short-sentence reading tasks, and their acoustic features, including temporal features (such as duration of utterance, number and length of pauses) and spectral features (F0, F1, and F2), were used to build a machine learning model to predict their cognitive impairments.

Results: The classification metrics from the healthy controls were evaluated through the area under the receiver operating characteristic curve and were found to be 0.61, 0.67, and 0.77 for mild cognitive impairment, global cognitive impairment, and mild cognitive impairment with global cognitive impairment, respectively.

Conclusion: Our machine learning model revealed that individuals’ acoustic features can be employed to discriminate between healthy controls and those with mild cognitive impairment with global cognitive impairment, which is a more severe form of cognitive impairment compared with mild cognitive impairment or global cognitive impairment alone. It is suggested that language impairment increases in severity with cognitive impairment.

Top-down activation of the visuo-orthographic system during spoken sentence processing

The left ventral occipitotemporal cortex (vOT) is considered the key area of the visuo-orthographic system. However, some studies reported that the area is also involved in speech processing tasks, especially those that require activation of orthographic knowledge. These findings suggest the existence of a top-down activation mechanism allowing such cross-modal activation. Yet, little is known about the involvement of the vOT in more natural speech processing situations like spoken sentence processing. Here, we addressed this issue in a functional Magnetic Resonance Imaging (fMRI) study while manipulating the impacts of two factors, i.e., task demands (semantic vs. low-level perceptual task) and the quality of speech signals (sentences presented against clear vs. noisy background). Analyses were performed at the levels of whole brain and region-of-interest (ROI) focusing on the vOT voxels individually identified through a reading task. Whole brain analysis showed that processing spoken sentences induced activity in a large network including the regions typically involved in phonological, articulatory, semantic and orthographic processing. ROI analysis further specified that a significant part of the vOT voxels that responded to written words also responded to spoken sentences, thus, suggesting that the same area within the left occipitotemporal pathway contributes to both reading and speech processing. Interestingly, both analyses provided converging evidence that vOT responses to speech were sensitive to both task demands and quality of speech signals: Compared to the low-level perceptual task, activity of the area increased when efforts on comprehension were required. The impact of background noise depended on task demands. It led to a decrease of vOT activity in the semantic task but not in the low-level perceptual task. Our results provide new insights into the function of this key area of the reading network, notably by showing that its speech-induced top-down activation also generalizes to ecological speech processing situations.

Task Engagement and the Vigilance Decrement Revisited: Expanding Upon the Work of Joel S. Warm Using a Semantic Vigilance Paradigm

OBJECTIVE

The goal of the present study is twofold: (1) demonstrate the importance of measuring and understanding the relationship between task engagement and vigilance performance, and (2) celebrate the work of Joel S. Warm and expand upon his previous research in two semantic vigilance paradigms.

BACKGROUND

The importance of measuring task engagement in cognitive and sensory vigilance tasks has been well documented. But to date, our understanding of the effects of task engagement on semantic vigilance performance is limited.

METHOD

Seventy-three participants completed either a standard semantic vigilance task or a lure semantic vigilance task. Participants also completed subjective measures of workload and stress.

RESULTS

The results indicated that changes in task engagement are associated with correct detection performance. Changes in task engagement may be related to individual differences in the distress associated with performing semantic vigilance tasks.

CONCLUSION

In line with the work of Warm and his colleagues (Dember, Warm, Bowers, & Lanzetta, 1984), participants who reported increased task engagement after the vigil outperformed their peers who noted decreased task engagement upon conclusion of the task. Participants reporting increases in engagement with the semantic vigilance tasks also reported significantly greater distress pretask, but not posttask. Instead, increases in postvigil distress were driven by the task to which participants were assigned, not task engagement.

APPLICATION

The present study has several implications for applied settings that involve long duration semantic processing or semantic target identification. Such real-world tasks include aviation, cyber threat detection and analysis, driving, and reading.

Steady state visual evoked potentials in reading aloud: Effects of lexicality, frequency and orthographic familiarity

The present study explored the possibility to use Steady-State Visual Evoked Potentials (SSVEPs) as a tool to investigate the core mechanisms in visual word recognition. In particular, we investigated three benchmark effects of reading aloud: lexicality (words vs. pseudowords), frequency (high-frequency vs. low-frequency words), and orthographic familiarity ('familiar' versus 'unfamiliar' pseudowords). We found that words and pseudowords elicited robust SSVEPs. Words showed larger SSVEPs than pseudowords and high-frequency words showed larger SSVEPs than low-frequency words. SSVEPs were not sensitive to orthographic familiarity. We further localized the neural generators of the SSVEP effects. The lexicality effect was located in areas associated with early level of visual processing, i.e. in the right occipital lobe and in the right precuneus. Pseudowords produced more activation than words in left sensorimotor areas, rolandic operculum, insula, supramarginal gyrus and in the right temporal gyrus. These areas are devoted to speech processing and/or spelling-to-sound conversion. The frequency effect involved the left temporal pole and orbitofrontal cortex, areas previously implicated in semantic processing and stimulus-response associations respectively, and the right postcentral and parietal inferior gyri, possibly indicating the involvement of the right attentional network.

Neural correlates of the lexicality effect in children

The comparison of words and pseudowords has been extensively used in adult neuroimaging studies to inform neurocognitive models of reading but has rarely been used to inform models of reading acquisition. Using a rhyming judgment task, the current study examined age-related differences in the spelling to sound mapping mechanisms involved in word and pseudoword reading. We hypothesized a developmental increase in specialization of the brain mechanisms engaged for word and pseudoword processing. Consistent with adult studies, children in the current study demonstrated a greater activation for words as compared to pseudowords in the anterior left ventral occipito-temporal cortex (vOT). Inconsistent with adult studies, children also showed greater activation for words as compared to pseudowords in the mid-posterior left vOT, indicating a robust semantic influence on orthographic processing in young readers. Furthermore, our results did not indicate a lexicality by age interaction for 8- to 13-year-old children, suggesting that the adult-like specialization in the left vOT only appears later in development.

The Pre-attentive L2 Orthographic Perception Mechanism Utilized by Bilinguals with Different Proficiency Levels

Language proficiency is predicted to modulate orthographic-semantic association in second language (L2) vocabulary acquisition, in accordance with the assumptions of the Developmental Bilingual Interactive-Activation model (BIA-d) (Grainger et al., 2010). The current study explored this modulation during pre-attentive L2 orthographic perception. ERPs were recorded from Chinese–English bilinguals with different L2 proficiency during their pre-attentive response to deviant and standard stimuli arranged in the oddball paradigm. Two stimulus types were investigated separately: L2 orthography and L1 orthography. In the L2 orthography condition, a MMN-N400 complex (i.e., deviancy effect) was found in the high L2 proficiency bilinguals, but only a marginally significant reduced negativity in an early time window was found in the low L2 proficiency bilinguals. In the L1 orthography condition, the high and low L2 proficiency bilinguals showed similar deviancy effect in the form of MMN-P3a-LPC complex. The current findings suggest that proficiency modulates pre-attentive L2 orthographic perception, such that the high L2 proficiency bilinguals activate the associated semantic representation instantly upon orthographic decoding, while the orthographic-semantic connection is not activated for the low L2 proficiency bilinguals. This is probably due to their difference in the strength of orthographic-semantic association. These findings contribute to the understanding of orthographic processing by bilinguals at the pre-attentive level and provide supporting evidence for the BIA-d model.