Processing lexical semantic and syntactic information in first and second language: fMRI evidence from German and Russian

We introduce two experiments that explored syntactic and semantic processing of spoken sentences by native and non-native speakers. In the first experiment, the neural substrates corresponding to detection of syntactic and semantic violations were determined in native speakers of two typologically different languages using functional magnetic resonance imaging (fMRI). The results show that the underlying neural response of participants to stimuli across different native languages is quite similar. In the second experiment, we investigated how non-native speakers of a language process the same stimuli presented in the first experiment. First, the results show a more similar pattern of increased activation between native and non-native speakers in response to semantic violations than to syntactic violations. Second, the non-native speakers were observed to employ specific portions of the frontotemporal language network differently from those employed by native speakers. These regions included the inferior frontal gyrus (IFG), superior temporal gyrus (STG), and subcortical structures of the basal ganglia.     

Electrophysiological correlates of the drift diffusion model in visual word recognition

This study was designed to explore the electrophysiological correlates of the diffusion models drift rate parameter in cognitive decision making. Eighty‐two participants completed a lexical decision task while their stimulus‐dependent event‐related potentials (ERP) and theta frequency band power were measured. A mass univariate approach was applied to examine the timeline at which correlations were evident. Individual differences in drift rate parameter and condition‐wise within‐subject differences in drift rates for word emotionality and item repetition were found to be related to amplitude differences in the late positive complex (LPC). No relations to theta frequency band power changes were obtained. The drift rate parameter captures information accumulation of noisy evidence, while LPC amplitudes are discussed to reflect the strength of a memory trace. While these results point to a common underlying cognitive mechanism to explain drift rates and LPC modulation, they also provide a new angle on the timeline of visual word processing following word identification. Further confirmations of the results are needed to approve the LPC as neurophysiological marker of information accumulation. Hum Brain Mapp 38:5616–5627, 2017. © 2017 Wiley Periodicals, Inc.     

Structural atrophy of the right superior frontal gyrus in adolescents with severe irritability

Severe irritability is common in youths with psychiatric disorders and results in significant dysfunction across domains (academic, social, and familial). Prior structural MRI studies in the pediatric population demonstrated that aberrations of cortical thickness (CT) and gray matter volume (GMV) in the fronto‐striatal‐temporal regions which have been associated with irritability. However, the directions of the correlations between structural alteration and irritability in the individual indices were not consistent. Thus, we aim to address this by implementing comprehensive assessments of CT, GMV, and local gyrification index (LGI) simultaneously in youths with severe levels of irritability by voxel‐based morphometry and surface‐based morphometry. One hundred and eight adolescents (46 youths with severe irritability and 62 healthy youths, average age = 14.08 years, standard deviation = 2.36) were scanned with a T1‐weighted MRI sequence. The severity of irritability was measured using the affective reactivity index. In youths with severe irritability, there was decreased CT, GMV, and LGI in the right superior frontal gyrus (SFG) compared to healthy youths, and negative correlations between these indices of the SFG and irritability. Our findings suggest that structural deficits in the SFG, potentially related to its role in inhibitory control, may be critical for the neurobiology of irritability.     

Specialization of phonological and semantic processing in Chinese word reading

The purpose of this study was to examine the neurocognitive network for processing visual word forms in native Chinese speakers using functional magnetic resonance imaging (fMRI). In order to compare the processing of phonological and semantic representations, we developed parallel rhyming and meaning association judgment tasks that required explicit access and manipulation of these representations. Subjects showed activation in left inferior/middle frontal gyri, bilateral medial frontal gyri, bilateral middle occipital/fusiform gyri, and bilateral cerebella for both the rhyming and meaning tasks. A direct comparison of the tasks revealed that the rhyming task showed more activation in the posterior dorsal region of the inferior/middle frontal gyrus (BA 9/44) and in the inferior parietal lobule (BA 40). The meaning task showed more activation in the anterior ventral region of the inferior/middle frontal gyrus (BA 47) and in the superior/middle temporal gyrus (BA 22,21). These findings are consistent with previous studies in English that suggest specialization of inferior frontal regions for the access and manipulation of phonological vs. semantic representations, but also suggest that this specialization extends to the middle frontal gyrus for Chinese. These findings are also consistent with the suggestion that the left middle temporal gyrus is involved in representing semantic information and the left inferior parietal lobule is involved in mapping between orthographic and phonological representations.     

Combined ERP/fMRI evidence for early word recognition effects in the posterior inferior temporal gyrus

Two brain regions with established roles in reading are the posterior middle temporal gyrus and the posterior fusiform gyrus (FG). Lesion studies have also suggested that the region located between them, the posterior inferior temporal gyrus (pITG), plays a central role in word recognition. However, these lesion results could reflect disconnection effects since neuroimaging studies have not reported consistent lexicality effects in pITG. Here we tested whether these reported pITG lesion effects are due to disconnection effects or not using parallel Event-related Potentials (ERP)/functional magnetic resonance imaging (fMRI) studies. We predicted that the Recognition Potential (RP), a left-lateralized ERP negativity that peaks at about 200–250 msec, might be the electrophysiological correlate of pITG activity and that conditions that evoke the RP (perceptual degradation) might therefore also evoke pITG activity. In Experiment 1, twenty-three participants performed a lexical decision task (temporally flanked by supraliminal masks) while having high-density 129-channel ERP data collected. In Experiment 2, a separate group of fifteen participants underwent the same task while having fMRI data collected in a 3T scanner. Examination of the ERP data suggested that a canonical RP effect was produced. The strongest corresponding effect in the fMRI data was in the vicinity of the pITG. In addition, results indicated stimulus-dependent functional connectivity between pITG and a region of the posterior FG near the Visual Word Form Area (VWFA) during word compared to nonword processing. These results provide convergent spatiotemporal evidence that the pITG contributes to early lexical access through interaction with the VWFA.     

Near‐infrared spectroscopy reveals neural perception of vocal emotions in human neonates

Processing affective prosody, that is the emotional tone of a speaker, is fundamental to human communication and adaptive behaviors. Previous studies have mainly focused on adults and infants; thus the neural mechanisms underlying the processing of affective prosody in newborns remain unclear. Here, we used near‐infrared spectroscopy to examine the ability of 0‐to‐4‐day‐old neonates to discriminate emotions conveyed by speech prosody in their maternal language and a foreign language. Happy, fearful, and angry prosodies enhanced neural activation in the right superior temporal gyrus relative to neutral prosody in the maternal but not the foreign language. Happy prosody elicited greater activation than negative prosody in the left superior frontal gyrus and the left angular gyrus, regions that have not been associated with affective prosody processing in infants or adults. These findings suggest that sensitivity to affective prosody is formed through prenatal exposure to vocal stimuli of the maternal language. Furthermore, the sensitive neural correlates appeared more distributed in neonates than infants, indicating a high‐level of neural specialization between the neonatal stage and early infancy. Finally, neonates showed preferential neural responses to positive over negative prosody, which is contrary to the “negativity bias” phenomenon established in adult and infant studies.     

Visceromotor roots of aesthetic evaluation of pain in art: an fMRI study

Empathy for pain involves sensory and visceromotor brain regions relevant also in the first-person pain experience. Focusing on brain activations associated with vicarious experiences of pain triggered by artistic or non-artistic images, the present study aims to investigate common and distinct brain activation patterns associated with these two vicarious experiences of pain and to assess whether empathy for pain brain regions contributes to the formation of an aesthetic judgement (AJ) in non-art expert observers. Artistic and non-artistic facial expressions (painful and neutral) were shown to participants inside the scanner and then aesthetically rated in a subsequent behavioural session. Results showed that empathy for pain brain regions (i.e. bilateral insular cortex, posterior sector of the anterior cingulate cortex and the anterior portion of the middle cingulate cortex) and bilateral inferior frontal gyrus are commonly activated by artistic and non-artistic painful facial expressions. For the artistic representation of pain, the activity recorded in these regions directly correlated with participants’ AJ. Results also showed the distinct activation of a large cluster located in the posterior cingulate cortex/precuneus for non-artistic stimuli. This study suggests that non-beauty-specific mechanisms such as empathy for pain are crucial components of the aesthetic experience of artworks.     

Complementary circuits connecting the orbital and medial prefrontal networks with the temporal, insular, and opercular cortex in the macaque monkey

The origin and termination of axonal connections between the orbital and medial prefrontal cortex (OMPFC) and the temporal, insular, and opercular cortex have been analyzed with anterograde and retrograde axonal tracers, injected in the OMPFC or temporal cortex. The results show that there are two distinct, complementary, and reciprocal neural systems, related to the previously defined "orbital" and "medial" prefrontal networks. The orbital prefrontal network, which includes areas in the central and lateral part of the orbital cortex, is connected with vision-related areas in the inferior temporal cortex (especially area TEav) and the fundus and ventral bank of the superior temporal sulcus (STSf/v), and with somatic sensory-related areas in the frontal operculum (OPf) and dysgranular insular area (Id). No connections were found between the orbital network and auditory areas. The orbital network is also connected with taste and olfactory cortical areas and the perirhinal cortex and appears to be involved in assessment of sensory objects, especially food. The medial prefrontal network includes areas on the medial surface of the frontal lobe, medial orbital areas, and two caudolateral orbital areas. It is connected with the rostral superior temporal gyrus (STGr) and the dorsal bank of the superior temporal sulcus (STSd). This region is rostral to the auditory parabelt areas, and there are only relatively light connections between the auditory areas and the medial network. This system, which is also connected with the entorhinal, parahippocampal, and cingulate/retrosplenial cortex, may be involved in emotion and other self-referential processes.     

Neurophysiological correlates of word processing deficits in isolated reading and isolated spelling disorders

Objective

In consistent orthographies, isolated reading disorders (iRD) and isolated spelling disorders (iSD) are nearly as common as combined reading-spelling disorders (cRSD). However, the exact nature of the underlying word processing deficits in isolated versus combined literacy deficits are not well understood yet.

Syllable frequency effects in French visual word recognition: an ERP study

This study examined event-related potentials (ERPs) associated with differences in the frequency of the initial syllable of target words whose syllabic structure provided either a match or mismatch with the /CV/ and /CVC/ syllables under analysis. Results showed ERP effects that were consistent with syllabic activation between 300 and 600 ms, with high frequency syllables producing more positive potentials than those of low frequency. The syllabic locus of these effects was verified by their presence only in the matched syllabic condition, showing that frequency effects respected known syllable boundaries. Syllable frequency effects were also noted in an earlier time window, between 150 and 300 ms. However, these effects were only seen when manipulating /CVC/ frequency, not /CV/, and were common to both the matched and unmatched conditions. These results suggest that phoneme representations are directly activated following presentation of a printed word, and syllable representations are only activated following phoneme activation.     

Subdivisions and connectional networks of the lateral prefrontal cortex in the macaque monkey

Neuroanatomical studies have long indicated that corticocortical connections are organized in networks that relate distinct sets of areas. Such networks have been emphasized by development of functional imaging methods for correlating activity across the cortex. Previously, two networks were recognized in the orbitomedial prefrontal cortex, the “orbital” and “medial” networks (OPFC and MPFC, respectively). In this study, three additional networks are proposed for the lateral prefrontal cortex: 1) a ventrolateral network (VLPFC) in and ventral to the principal sulcus; 2) a dorsal network (DPFC) in and dorsal to the principal sulcus and in the frontal pole; 3) a caudolateral network (CLPFC) in and rostral to the arcuate sulcus and the caudal principal sulcus. The connections of the first two networks are described here. Areas in each network are connected primarily with other areas in the same network, with overlaps around the principal sulcus. The VLPFC and DPFC are also connected with the OPFC and MPFC, respectively. Outside the prefrontal cortex, the VLPFC connects with specific areas related to somatic/visceral sensation and vision, in the frontoparietal operculum, insula, ventral bank/fundus of the superior temporal sulcus, inferior temporal gyrus, and inferior parietal cortex. In contrast, the DPFC connects with the rostral superior temporal gyrus, dorsal bank of the superior temporal sulcus, parahippocampal cortex, and posterior cingulate and retrosplenial cortex. Area 45a, in caudal VLPFC, is unique, having connections with all the networks. Its extrinsic connections resemble those of the DPFC. In addition, it has connections with both auditory belt/parabelt areas, and visual related areas. J. Comp. Neurol. 522:1641–1690, 2014. © 2013 Wiley Periodicals, Inc.     

The neural basis of semantic cognition in Mandarin Chinese: A combined fMRI and TMS study

While converging sources of evidence point to the possibility of a large‐scale distributed network for semantic cognition, a consensus regarding the underlying subregions and their specific function in this network has not been reached. In the current study, we combined functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) methodology to investigate the neural basis of semantic cognition in Mandarin Chinese. In the fMRI experiment, strong activations were observed in left inferior frontal gyrus (IFG) and left middle temporal gyrus (MTG) for semantic judgment task. Moreover, functional connectivity was found from seed region left IFG to left MTG. Meanwhile, negative correlation between performance and extracted parameter estimates from left IFG to left MTG was detected in semantic task. Subsequent TMS stimulation over left IFG resulted in performance deficits in semantic judgment task, in contrast to other three sites: left MTG, right intraparietal sulcus (IPS) and a control site. We concluded that the neural basis of semantic processing for Mandarin Chinese closely resembled that for alphabetic languages such as English, supporting a language‐universal view on semantic cognition.     

The neural correlates of morphological complexity processing: Detecting structure in pseudowords

Morphological complexity is a highly debated issue in visual word recognition. Previous neuroimaging studies have shown that speakers are sensitive to degrees of morphological complexity. Two‐step derived complex words (bridging through bridge_N > bridge_V > bridging) led to more enhanced activation in the left inferior frontal gyrus than their 1‐step derived counterparts (running through run_V > running). However, it remains unclear whether sensitivity to degrees of morphological complexity extends to pseudowords. If this were the case, it would indicate that abstract knowledge of morphological structure is independent of lexicality. We addressed this question by investigating the processing of two sets of pseudowords in German. Both sets contained morphologically viable two‐step derived pseudowords differing in the number of derivational steps required to access an existing lexical representation and therefore the degree of structural analysis expected during processing. Using a 2 × 2 factorial design, we found lexicality effects to be distinct from processing signatures relating to structural analysis in pseudowords. Semantically‐driven processes such as lexical search showed a more frontal distribution while combinatorial processes related to structural analysis engaged more parietal parts of the network. Specifically, more complex pseudowords showed increased activation in parietal regions (right superior parietal lobe and left precuneus) relative to pseudowords that required less structural analysis to arrive at an existing lexical representation. As the two sets were matched on cohort size and surface form, these results highlight the role of internal levels of morphological structure even in forms that do not possess a lexical representation.     

Selective visual attention to emotional words: Early parallel frontal and visual activations followed by interactive effects in visual cortex

Human brains spontaneously differentiate between various emotional and neutral stimuli, including written words whose emotional quality is symbolic. In the electroencephalogram (EEG), emotional–neutral processing differences are typically reflected in the early posterior negativity (EPN, 200–300 ms) and the late positive potential (LPP, 400–700 ms). These components are also enlarged by task‐driven visual attention, supporting the assumption that emotional content naturally drives attention. Still, the spatio‐temporal dynamics of interactions between emotional stimulus content and task‐driven attention remain to be specified. Here, we examine this issue in visual word processing. Participants attended to negative, neutral, or positive nouns while high‐density EEG was recorded. Emotional content and top‐down attention both amplified the EPN component in parallel. On the LPP, by contrast, emotion and attention interacted: Explicit attention to emotional words led to a substantially larger amplitude increase than did explicit attention to neutral words. Source analysis revealed early parallel effects of emotion and attention in bilateral visual cortex and a later interaction of both in right visual cortex. Distinct effects of attention were found in inferior, middle and superior frontal, paracentral, and parietal areas, as well as in the anterior cingulate cortex (ACC). Results specify separate and shared mechanisms of emotion and attention at distinct processing stages. Hum Brain Mapp 37:3575–3587, 2016. © 2016 Wiley Periodicals, Inc .     

EEG reveals an early influence of social conformity on visual processing in group pressure situations

Humans are social beings and often have to perceive and perform within groups. In conflict situations, this puts them under pressure to either adhere to the group opinion or to risk controversy with the group. Psychological experiments have demonstrated that study participants adapt to erroneous group opinions in visual perception tasks, which they can easily solve correctly when performing on their own. Until this point, however, it is unclear whether this phenomenon of social conformity influences early stages of perception that might not even reach awareness or later stages of conscious decision-making. Using electroencephalography, this study has revealed that social conformity to the wrong group opinion resulted in a decrease of the posterior-lateral P1 in line with a decrease of the later centro-parietal P3. These results suggest that group pressure situations impact early unconscious visual perceptual processing, which results in a later diminished stimulus discrimination and an adaptation even to the wrong group opinion. These findings might have important implications for understanding social behavior in group settings and are discussed within the framework of social influence on eyewitness testimony.     

Brain regions involved in human movement perception: a quantitative voxel-based meta-analysis

Face, hands, and body movements are powerful signals essential for social interactions. In the last 2 decades, a large number of brain imaging studies have explored the neural correlates of the perception of these signals. Formal synthesis is crucially needed, however, to extract the key circuits involved in human motion perception across the variety of paradigms and stimuli that have been used. Here, we used the activation likelihood estimation (ALE) meta-analysis approach with random effect analysis. We performed meta-analyses on three classes of biological motion: movement of the whole body, hands, and face. Additional analyses of studies of static faces or body stimuli and sub-analyses grouping experiments as a function of their control stimuli or task employed allowed us to identify main effects of movements and forms perception, as well as effects of task demand. In addition to specific features, all conditions showed convergence in occipito-temporal and fronto-parietal regions, but with different peak location and extent. The conjunction of the three ALE maps revealed convergence in all categories in a region of the right posterior superior temporal sulcus as well as in a bilateral region at the junction between middle temporal and lateral occipital gyri. Activation in these regions was not a function of attentional demand and was significant also when controlling for non-specific motion perception. This quantitative synthesis points towards a special role for posterior superior temporal sulcus for integrating human movement percept, and supports a specific representation for body parts in middle temporal, fusiform, precentral, and parietal areas.     

Dissociable effects of phonetic competition and category typicality in a phonetic categorization task: an fMRI investigation

The current study used fMRI to explore the extent to which neural activation patterns in the processing of speech are driven by the quality of a speech sound as a member of its phonetic category, that is, its category typicality, or by the competition inherent in resolving the category membership of stimuli which are similar to other possible speech sounds. Subjects performed a phonetic categorization task on synthetic stimuli ranging along a voice-onset time continuum from [da] to [ta]. The stimulus set included sounds at the extreme ends of the voicing continuum which were poor phonetic category exemplars, but which were minimally competitive, stimuli near the phonetic category boundary, which were both poor exemplars of their phonetic category and maximally competitive, and stimuli in the middle of the range which were good exemplars of their phonetic category. Results revealed greater activation in bilateral inferior frontal areas for stimuli with the greatest degree of competition, consistent with the view that these areas are involved in selection between competing alternatives. In contrast, greater activation was observed in bilateral superior temporal gyri for the least prototypical phonetic category exemplars, irrespective of competition, consistent with the view that these areas process the acoustic-phonetic details of speech to resolve a token's category membership. Taken together, these results implicate separable neural regions in two different aspects of phonetic categorization.     

Predictability affects early perceptual processing of word onsets in continuous speech

Event-related potential (ERP) evidence indicates that listeners selectively attend to word onsets in continuous speech, but the reason for this preferential processing is unknown. The current study measured ERPs elicited by syllable onsets in an artificial language to test the hypothesis that listeners direct attention to word onsets because their identity is unpredictable. Both before and after recognition training, participants listened to a continuous stream of six nonsense words arranged in pairs, such that the second word in each pair was completely predictable. After training, first words in pairs elicited a larger negativity beginning around 100 ms after onset. This effect was not evident for the completely predictable second words in pairs. These results suggest that listeners are most likely to attend to the segments in speech that they are least able to predict.     

Neural correlates of processing emotional prosody in unipolar depression

Major depressive disorder (MDD) is characterized by a biased emotion perception. In the auditory domain, MDD patients have been shown to exhibit attenuated processing of positive emotions expressed by speech melody (prosody). So far, no neuroimaging studies examining the neural basis of altered processing of emotional prosody in MDD are available. In this study, we addressed this issue by examining the emotion bias in MDD during evaluation of happy, neutral, and angry prosodic stimuli on a five‐point Likert scale during functional magnetic resonance imaging (fMRI). As expected, MDD patients rated happy prosody less intense than healthy controls (HC). At neural level, stronger activation in the middle superior temporal gyrus (STG) and the amygdala was found in all participants when processing emotional as compared to neutral prosody. MDD patients exhibited an increased activation of the amygdala during processing prosody irrespective of valence while no significant differences between groups were found for the STG, indicating that altered processing of prosodic emotions in MDD occurs rather within the amygdala than in auditory areas. Concurring with the valence‐specific behavioral effect of attenuated evaluation of positive prosodic stimuli, activation within the left amygdala of MDD patients correlated with ratings of happy, but not neutral or angry prosody. Our study provides first insights in the neural basis of reduced experience of positive information and an abnormally increased amygdala activity during prosody processing.     

Neural networks involved in voluntary and involuntary vocal pitch regulation in experienced singers

In an fMRI experiment, we tested experienced singers with singing tasks to investigate neural correlates of voluntary and involuntary vocal pitch regulation. We shifted the pitch of auditory feedback (±25 or 200 cents), and singers either: (1) ignored the shift and maintained their vocal pitch or (2) changed their vocal pitch to compensate for the shift. In our previous study, singers successfully ignored and compensated for 200-cent shifts; in the present experiment, we hypothesized that singers would be less able to ignore 25-cent shifts, due to a prepotent, corrective pitch-shift response. We expected that voluntary vocal regulation during compensate tasks would recruit the anterior portion of the rostral cingulate zone (RCZa) and posterior superior temporal sulcus (pSTS), as our earlier study reported; however, we predicted that a different network may be engaged during involuntary responses to 25-cent shifts. Singers were less able to ignore 25-cent shifts than 200-cent shifts, suggesting that pitch-shift responses to small shifts are under less voluntary control than responses to larger shifts. While we did not find neural activity specifically associated with involuntary pitch-shift responses, compensate tasks recruited a functionally connected network consisting of RCZa, pSTS, and anterior insula. Analyses of stimulus-modulated functional connectivity suggest that pSTS and intraparietal sulcus may monitor auditory feedback to extract pitch-shift direction in 200-cent tasks, but not in 25-cent tasks, which suggests that larger vocal corrections are under cortical control. During the compensate tasks, the pSTS may interact with the RCZa and anterior insula before voluntary vocal pitch correction occurs.