Left Inferior Frontal Regions Research Articles

Localizing Syntactic Composition with Left-Corner Recurrent Neural Network Grammars.

In computational neurolinguistics, it has been demonstrated that hierarchical models such as recurrent neural network grammars (RNNGs), which jointly generate word sequences and their syntactic structures via the syntactic composition, better explained human brain activity than sequential models such as long short-term memory networks (LSTMs). However, the vanilla RNNG has employed the top-down parsing strategy, which has been pointed out in the psycholinguistics literature as suboptimal especially for head-final/left-branching languages, and alternatively the left-corner parsing strategy has been proposed as the psychologically plausible parsing strategy. In this article, building on this line of inquiry, we investigate not only whether hierarchical models like RNNGs better explain human brain activity than sequential models like LSTMs, but also which parsing strategy is more neurobiologically plausible, by developing a novel fMRI corpus where participants read newspaper articles in a head-final/left-branching language, namely Japanese, through the naturalistic fMRI experiment. The results revealed that left-corner RNNGs outperformed both LSTMs and top-down RNNGs in the left inferior frontal and temporal-parietal regions, suggesting that there are certain brain regions that localize the syntactic composition with the left-corner parsing strategy.

Bilingual Spatial Cognition: Spatial Cue Use in Bilinguals and Monolinguals.

Structural plasticity changes and functional differences in executive control tasks have been reported in bilinguals compared to monolinguals, supporting a proposed bilingual 'advantage' in executive control functions (e.g., task switching) due to continual usage of control mechanisms that inhibit one of the coexisting languages. However, it remains unknown whether these differences are also apparent in the spatial domain. The present fMRI study explores the use of spatial cues in 15 bilinguals and 14 monolinguals while navigating in an open-field virtual environment. In each trial, participants had to navigate towards a target object that was visible during encoding but hidden in retrieval. An extensive network was activated in bilinguals compared to monolinguals in the encoding and retrieval phase. During encoding, bilinguals activated the right temporal and left parietal regions (object trials) and left inferior frontal, precentral, and lingual regions more than monolinguals. During retrieval, the same contrasts activated the left caudate nucleus and the right dorsolateral prefrontal cortex (DLPFC), the left parahippocampal gyrus, as well as caudate regions. These results suggest that bilinguals may recruit neural networks known to subserve not only executive control processes but also spatial strategies.

Alterations in cerebral glucose metabolism measured by FDG PET in subjects performing a meditation practice based on clitoral stimulation

Background The relationship between sexuality, or the libido, and spirituality or religion has long been debated in psychiatry. Recent studies have explored the neurophysiology of both sexual experiences and spiritual practices such as meditation or prayer. In the present study, we report changes in cerebral glucose metabolism in a unique meditation practice augmented by clitoral stimulation called, Orgasmic Meditation, in which a spiritual state is described to be attained by both male and female participants engaged in the practice as a pair. Methods Male (N=20) and female (N=20) subjects had an intravenous catheter connected to a bag of normal saline inserted prior to the practice. During the practice, men stimulated their partner’s clitoris for exactly 15 minutes (he received no sexual stimulation). Midway through the practice, researchers injected 18F-fluorodeoxyglucose so the scan would reflect cerebral metabolism during the practice. Positron emission tomography (PET) imaging was performed approximately 30 minutes later. Results In the female participants, the meditation state showed significant decreases in the left inferior frontal, inferior parietal, insula, middle temporal, and orbitofrontal regions as well as in the right angular gyrus, anterior cingulate and parahippocampus compared to a neutral state (p<0.01). Male subjects had significant decreases in the left middle frontal, paracentral, precentral, and postcentral regions as well as the right middle frontal and paracentral regions during meditation (p<0.01). Men also had significantly increased metabolism in the cerebellum and right postcentral and superior temporal regions (p<0.01). Conclusions These findings represent a distinct pattern of brain activity, for both men and women, that is a hybrid between that of other meditation practices and sexual stimulation. Such findings have potential psychotherapeutic implications and may deepen our understanding of the relationship between spiritual and sexual experience.

Role of articulatory motor networks in perceptual categorization of speech signals: a 7T fMRI study.

Speech and language processing involve complex interactions between cortical areas necessary for articulatory movements and auditory perception and a range of areas through which these are connected and interact. Despite their fundamental importance, the precise mechanisms underlying these processes are not fully elucidated. We measured BOLD signals from normal hearing participants using high-field 7 Tesla fMRI with 1-mm isotropic voxel resolution. The subjects performed 2 speech perception tasks (discrimination and classification) and a speech production task during the scan. By employing univariate and multivariate pattern analyses, we identified the neural signatures associated with speech production and perception. The left precentral, premotor, and inferior frontal cortex regions showed significant activations that correlated with phoneme category variability during perceptual discrimination tasks. In addition, the perceived sound categories could be decoded from signals in a region of interest defined based on activation related to production task. The results support the hypothesis that articulatory motor networks in the left hemisphere, typically associated with speech production, may also play a critical role in the perceptual categorization of syllables. The study provides valuable insights into the intricate neural mechanisms that underlie speech processing.

Phonological and morphological literacy skills in English and Chinese: A cross-linguistic neuroimaging comparison of Chinese-English bilingual and monolingual English children.

Over the course of literacy development, children learn to recognize word sounds and meanings in print. Yet, they do so differently across alphabetic and character-based orthographies such as English and Chinese. To uncover cross-linguistic influences on children's literacy, we asked young Chinese-English simultaneous bilinguals and English monolinguals (N = 119, ages 5-10) to complete phonological and morphological awareness (MA) literacy tasks. Children completed the tasks in the auditory modality in each of their languages during functional near-infrared spectroscopy neuroimaging. Cross-linguistically, comparisons between bilinguals' two languages revealed that the task that was more central to reading in a given orthography, such as phonological awareness (PA) in English and MA in Chinese, elicited less activation in the left inferior frontal and parietal regions. Group comparisons between bilinguals and monolinguals in English, their shared language of academic instruction, revealed that the left inferior frontal was less active during phonology but more active during morphology in bilinguals relative to monolinguals. MA skills are generally considered to have greater language specificity than PA skills. Bilingual literacy training in a skill that is maximally similar across languages, such as PA, may therefore yield greater automaticity for this skill, as reflected in the lower activation in bilinguals relative to monolinguals. This interpretation is supported by negative correlations between proficiency and brain activation. Together, these findings suggest that both the structural characteristics and literacy experiences with a given language can exert specific influences on bilingual and monolingual children's emerging brain networks for learning to read.

Slow neural oscillations explain temporal fluctuations in distractibility

Human environments comprise various sources of distraction, which often occur unexpectedly in time. The proneness to distraction (i.e., distractibility) is posited to be independent of attentional sampling of targets, but its temporal dynamics and neurobiological basis are largely unknown. Brain oscillations in the theta band (3 - 8Hz) have been associated with fluctuating neural excitability, which is hypothesised here to explain rhythmic modulation of distractibility. In a pitch discrimination task (N=30) with unexpected auditory distractors, we show that distractor-evoked neural responses in the electroencephalogram and perceptual susceptibility to distraction were co-modulated and cycled approximately 3 - 5 times per second. Pre-distractor neural phase in left inferior frontal and insular cortex regions explained fluctuating distractibility. Thus, human distractibility is not constant but fluctuates on a subsecond timescale. Furthermore, slow neural oscillations subserve the behavioural consequences of a hitherto largely unexplained but ever-increasing phenomenon in modern environments - distraction by unexpected sound.

The neonate brain's sensitivity to repetition-based structure: Specific to speech?

Newborns are able to extract and learn repetition-based regularities from the speech input, that is, they show greater brain activation in the bilateral temporal and left inferior frontal regions to trisyllabic pseudowords of the form AAB (e.g., "babamu") than to random ABC sequences (e.g., "bamuge"). Whether this ability is specific to speech or also applies to other auditory stimuli remains unexplored. To investigate this, we tested whether newborns are sensitive to regularities in musical tones. Neonates listened to AAB and ABC tones sequences, while their brain activity was recorded using functional Near-Infrared Spectroscopy (fNIRS). The paradigm, the frequency of occurrence and the distribution of the tones were identical to those of the syllables used in previous studies with speech. We observed a greater inverted (negative) hemodynamic response to AAB than to ABC sequences in the bilateral temporal and fronto-parietal areas. This inverted response was caused by a decrease in response amplitude, attributed to habituation, over the course of the experiment in the left fronto-temporal region for the ABC condition and in the right fronto-temporal region for both conditions. These findings show that newborns' ability to discriminate AAB from ABC sequences is not specific to speech. However, the neural response to musical tones and spoken language is markedly different. Tones gave rise to habituation, whereas speech was shown to trigger increasing responses over the time course of the study. Relatedly, the repetition regularity gave rise to an inverted hemodynamic response when carried by tones, while it was canonical for speech. Thus, newborns' ability to detect repetition is not speech-specific, but it engages distinct brain mechanisms for speech and music. RESEARCH HIGHLIGHTS: The ability of newborns' to detect repetition-based regularities is not specific to speech, but also extends to other auditory modalities. The brain mechanisms underlying speech and music processing are markedly different.

The Development of Left Hemisphere Lateralization for Sentence-Level Prosodic Processing.

The fine-tuning of linguistic prosody in later childhood is poorly understood, and its neurological processing is even less well studied. In particular, it is unknown if grammatical processing of prosody is left- or right-lateralized in childhood versus adulthood and how phonological working memory might modulate such lateralization. Furthermore, it is virtually unknown how prosody develops neurologically among children with cochlear implants (CIs). Normal-hearing (NH) children ages 6-12 years and NH adults ages 18-28 years completed a functional near-infrared spectroscopy neuroimaging task, during which they heard sentence pairs and judged whether the sentences did or did not differ in their overall prosody (declarative, question, with or without narrow focus). Children also completed standard measures of expressive and receptive language. Age group differences emerged; children exhibited stronger bilateral temporoparietal activity but reduced left frontal activation. Furthermore, children's performance on a nonword repetition test was significantly associated with activation in the left inferior frontal gyrus-an area that was generally more activated in adults than in children. The prosody-related findings are generally consistent with prior neurodevelopmental works on sentence comprehension, especially those involving syntax and semantics, which have also noted a developmental shift from bilateral temporal to left inferior frontal regions typically associated with increased sensitivity to sentence structure. The findings thus inform theoretical perspectives on brain and language development and have implications for studying the effects of CIs on neurodevelopmental processes for sentence prosody. https://doi.org/10.23641/asha.22255996.

Spared speech fluency is associated with increased functional connectivity in the speech production network in semantic variant primary progressive aphasia.

Semantic variant primary progressive aphasia is a clinical syndrome characterized by marked semantic deficits, anterior temporal lobe atrophy and reduced connectivity within a distributed set of regions belonging to the functional network associated with semantic processing. However, to fully depict the clinical signature of semantic variant primary progressive aphasia, it is necessary to also characterize preserved neural networks and linguistic abilities, such as those subserving speech production. In this case-control observational study, we employed whole-brain seed-based connectivity on task-free MRI data of 32 semantic variant primary progressive aphasia patients and 46 healthy controls to investigate the functional connectivity of the speech production network and its relationship with the underlying grey matter. We investigated brain-behaviour correlations with speech fluency measures collected through clinical tests (verbal agility) and connected speech (speech rate and articulation rate). As a control network, we also investigated functional connectivity within the affected semantic network. Patients presented with increased connectivity in the speech production network between left inferior frontal and supramarginal regions, independent of underlying grey matter volume. In semantic variant primary progressive aphasia patients, preserved (verbal agility) and increased (articulation rate) speech fluency measures correlated with increased connectivity between inferior frontal and supramarginal regions. As expected, patients demonstrated decreased functional connectivity in the semantic network (dependent on the underlying grey matter atrophy) associated with average nouns' age of acquisition during connected speech. Collectively, these results provide a compelling model for studying compensation mechanisms in response to disease that might inform the design of future rehabilitation strategies in semantic variant primary progressive aphasia.

Socioeconomic dissociations in the neural and cognitive bases of reading disorders

Childhood socioeconomic status (SES) strongly predicts disparities in reading development, yet it is unknown whether early environments also moderate the cognitive and neurobiological bases of reading disorders (RD) such as dyslexia, the most prevalent learning disability. SES-diverse 6–9-year-old children (n = 155, half with RD) completed behavioral and functional magnetic resonance imaging (fMRI) tasks engaging phonological and orthographic processing, which revealed corresponding double-dissociations in neurocognitive deficits. At the higher end of the SES spectrum, RD was most strongly explained by differences in phonological skill and corresponding activation in left inferior frontal and temporoparietal regions during phonological processing—widely considered the “core deficit” of RD. However, at the lower end of the SES spectrum, RD was most strongly explained by differences in rapid naming skills and corresponding activation in left temporoparietal and fusiform regions during orthographic processing. Findings indicate that children’s early environments systematically moderate the neurocognitive systems underlying RD, which has implications for assessment and treatment approaches to reduce SES disparities in RD outcomes. Further, results suggest that reliance on high-SES convenience samples may mask critical heterogeneity in the foundations of both typical and disordered reading development.

Alterations in cerebral glucose metabolism measured by FDG PET in subjects performing a meditation practice based on clitoral stimulation

Background: The relationship between sexuality, or the libido, and spirituality or religion has long been debated in psychiatry. Recent studies have explored the neurophysiology of both sexual experiences and spiritual practices such as meditation or prayer. In the present study, we report changes in cerebral glucose metabolism in a unique meditation practice augmented by clitoral stimulation called, Orgasmic Meditation, in which a spiritual state is described to be attained by both male and female participants engaged in the practice as a pair. Methods: Male (N=20) and female (N=20) subjects had an intravenous catheter connected to a bag of normal saline inserted prior to the practice. During the practice, men stimulated their partner’s clitoris for exactly 15 minutes (he received no sexual stimulation). Midway through the practice, researchers injected 18F-fluorodeoxyglucose so the scan would reflect cerebral metabolism during the practice. Positron emission tomography (PET) imaging was performed approximately 30 minutes later. Results: In the female participants, the meditation state showed significant decreases in the left inferior frontal, inferior parietal, insula, middle temporal, and orbitofrontal regions as well as in the right angular gyrus, anterior cingulate and parahippocampus compared to a neutral state (p<0.01). Male subjects had significant decreases in the left middle frontal, paracentral, precentral, and postcentral regions as well as the right middle frontal and paracentral regions during meditation (p<0.01). Men also had significantly increased metabolism in the cerebellum and right postcentral and superior temporal regions (p<0.01). Conclusions: These findings represent a distinct pattern of brain activity, for both men and women, that is a hybrid between that of other meditation practices and sexual stimulation. Such findings have potential psychotherapeutic implications and may deepen our understanding of the relationship between spiritual and sexual experience.

The Functional Neuroanatomy of Reading Intervention.

The present article reviews the literature on the brain mechanisms underlying reading improvements following behavioral intervention for reading disability. This includes evidence of neuroplasticity concerning functional brain activation, brain structure, and brain connectivity related to reading intervention. Consequently, the functional neuroanatomy of reading intervention is compared to the existing literature on neurocognitive models and brain abnormalities associated with reading disability. A particular focus is on the left hemisphere reading network including left occipito-temporal, temporo-parietal, and inferior frontal language regions. In addition, potential normalization/compensation mechanisms involving right hemisphere cortical regions, as well as bilateral sub-cortical and cerebellar regions are taken into account. The comparison of the brain systems associated with reading intervention and the brain systems associated with reading disability enhances our understanding of the neurobiological basis of typical and atypical reading development. All in all, however, there is a lack of sufficient evidence regarding rehabilitative brain mechanisms in reading disability, which we discuss in this review.

Speech sound categorization: The contribution of non-auditory and auditory cortical regions

Which processes in the human brain lead to the categorical perception of speech sounds? Investigation of this question is hampered by the fact that categorical speech perception is normally confounded by acoustic differences in the stimulus. By using ambiguous sounds, however, it is possible to dissociate acoustic from perceptual stimulus representations. Twenty-seven normally hearing individuals took part in an fMRI study in which they were presented with an ambiguous syllable (intermediate between /da/ and /ga/) in one ear and with disambiguating acoustic feature (third formant, F3) in the other ear. Multi-voxel pattern searchlight analysis was used to identify brain areas that consistently differentiated between response patterns associated with different syllable reports. By comparing responses to different stimuli with identical syllable reports and identical stimuli with different syllable reports, we disambiguated whether these regions primarily differentiated the acoustics of the stimuli or the syllable report. We found that BOLD activity patterns in left perisylvian regions (STG, SMG), left inferior frontal regions (vMC, IFG, AI), left supplementary motor cortex (SMA/pre-SMA), and right motor and somatosensory regions (M1/S1) represent listeners’ syllable report irrespective of stimulus acoustics. Most of these regions are outside of what is traditionally regarded as auditory or phonological processing areas. Our results indicate that the process of speech sound categorization implicates decision-making mechanisms and auditory-motor transformations.

Development of infants’ neural speech processing and its relation to later language skills: A MEG study

The ‘sensitive period’ for phonetic learning (∼6–12 months) is one of the earliest milestones in language acquisition where infants start to become specialized in processing speech sounds in their native language. In the last decade, advancements in neuroimaging technologies for infants are starting to shed light on the underlying neural mechanisms supporting this important learning period. The current study reports on a large longitudinal dataset with the aim to replicate and extend on two important questions: 1) what are the developmental changes during the ‘sensitive period’ for native and nonnative speech processing? 2) how does native and nonnative speech processing in infants predict later language outcomes? Fifty-four infants were recruited at 7 months of age and their neural processing of speech was measured using Magnetoencephalography (MEG). Specifically, the neural sensitivity to a native and a nonnative speech contrast was indexed by the mismatch response (MMR). They repeated the measurement again at 11 months of age and their language development was further tracked from 12 months to 30 months of age using the MacArthur-Bates Communicative Development Inventory (CDI). Using an a priori Region-of-Interest (ROI) approach, we observed significant increases for the Native MMR in the left inferior frontal region (IF) and superior temporal region (ST) from 7 to 11 months, but not for the Nonnative MMR. Complementary whole brain comparison revealed more widespread developmental changes for both contrasts. However, only individual differences in the left IF and ST for the Nonnative MMR at 11 months of age were significant predictors of individual vocabulary growth up to 30 months of age. An exploratory machine-learning based analysis further revealed that whole brain time series for both Native and Nonnative contrasts can robustly predict later outcomes, but with very different underlying spatial-temporal patterns. The current study extends our current knowledge and suggests that native and nonnative speech processing may follow different developmental trajectories and utilize different mechanisms that are relevant for later language skills.

Fluency test generation and errors in focal frontal and posterior lesions

The number produced on fluency tasks is widely used to measure voluntary response generation. To further evaluate the relationship between generation, errors, and the area of anatomical damage we administered eight fluency tasks (word, design, gesture, ideational) to a large group of focal frontal (n = 69) and posterior (n = 43) patients and controls (n = 150). Lesions were analysed by a finer-grained frontal localisation method, and traditional subdivisions (anterior/posterior, left/right frontal). Thus, we compared patients with Lateral lesions to patients with Medial lesions. Our results show that all fluency tasks are sensitive to frontal lobe damage for the number of correct responses and, for the first time, we provide evidence that seven fluency tasks show frontal sensitivity in terms of errors (perseverations, rule-breaks). Lateral (not Medial) patients produced the highest error rates, indicative of task-setting or monitoring difficulties. There was a right frontal effect for perseverative errors when retrieving known or stored items and rule-break errors when creating novel responses. Left lateral effects were specific to phonemic word fluency rule-breaks and perseverations for meaningless gesture fluency. In addition, our generation output and error findings support a frontal role in novelty processes. Finally, we confirm our previous generation findings suggesting critical roles of the superior medial region in energization and the left inferior frontal region in selection (Robinson et al., 2012). Overall, these results support the notion that frontal functions comprise a set of highly specialised cognitive processes, supported by distinct frontal regions.

Multi-model mapping of phonemic fluency.

The voluntary generation of non-overlearned responses is usually assessed with phonemic fluency. Like most frontal tasks, it draws upon different complex processes and systems whose precise nature is still incompletely understood. Many claimed aspects regarding the pattern of phonemic fluency performance and its underlying anatomy remain controversial. Major limitations of past investigations include small sample size, scant analysis of phonemic output and methodologically insufficient lesion analysis approaches. We investigated a large number of patients with focal unilateral right or left frontal (n = 110) or posterior (n = 100) or subcortical (n = 65) lesions imaged with magnetic resonance or computed tomography and compared their performance on the number of overall responses, words produced over time, extremely infrequent/unknown words and inappropriate words generated. We also employed, for the first time parcel‐based lesion-symptom mapping, tract-wise statistical analysis as well as Bayesian multi-variate analysis based on meta-analytically defined functional region of interest, including their interactions. We found that left frontal damage was associated with greater impairment than right frontal or posterior damage on overall fluency performance, suggesting that phonemic fluency shows specificity to frontal lesions. We also found that subcorticals, similar to frontals, performed significantly worse than posteriors on overall performance suggesting that subcortical regions are also involved. However, only frontal effects were found for words produced over time, extremely infrequent/unknown and inappropriate words. Parcel‐based lesion-symptom mapping analysis found that worse fluency performance was associated with damage to the posterior segment of the left frontal middle and superior gyrus, the left dorsal anterior cingulate gyrus and caudate nucleus. Tract-wise statistical analysis revealed that disconnections of left frontal tracts are critical. Bayesian multi-variate models of lesions and disconnectome maps implicated left middle and inferior frontal and left dorsomedial frontal regions. Our study suggests that a set of well localized left frontal areas together with subcortical regions and several left frontal tracts are critical for word generation. We speculate that a left lateralized network exists. It involves medial, frontal regions supporting the process of ‘energization’, which sustains activation for the duration of the task and middle and inferior frontal regions concerned with ‘selection’, required due to the competition produced by associated stored words, respectively. The methodology adopted represents a promising and empirically robust approach in furthering our understanding of the neurocognitive architecture underpinning executive processes.

Associated functional network development and language abilities in children

During childhood, the brain is gradually converging to the efficient functional architecture observed in adults. How the brain's functional architecture evolves with age, particularly in young children, is however, not well understood. We examined the functional connectivity of the core language regions, in association with cortical growth and language abilities, in 175 young children in the age range of 4 to 9 years. We analyzed the brain's developmental changes using resting-state functional and T1-weighted structural magnetic resonance imaging data. The results showed increased functional connectivity strength with age between the pars triangularis of the left inferior frontal gyrus and left temporoparietal regions (cohen's d = 0.54, CI: 0.24 - 0.84), associated with children's language abilities. Stronger functional connectivity between bilateral prefrontal and temporoparietal regions was associated with better language abilities regardless of age. In addition, the stronger functional connectivity between the left inferior frontal and temporoparietal regions was associated with larger surface area and thinner cortical thickness in these regions, which in turn was associated with superior language abilities. Thus, using functional and structural brain indices, coupled with behavioral measures, we elucidate the association of functional language network development, language ability, and cortical growth, thereby adding to our understanding of the neural basis of language acquisition in young children.

Early onset consumption of coca paste associated with executive-attention vulnerability markers linked to caudate-frontal structural and functional abnormalities

Coca paste is the most popular form of smoked cocaine (SC) in Latin America and also the most widespread among adolescents in vulnerable sectors of society, thus representing a significant public health concern. Despite evidence suggesting that abnormal executive-attention function is predictive of addiction to stimulant drugs, no study to date has compared clinically relevant neuropsychological (NPS) and physiological variables between individuals with histories of smoked cocaine dependence (SCD) and insufflated cocaine hydrochloride dependence (ICD). In this study we evaluated 25 SCD and 22 ICD subjects matched by poly-consumption profiles, and 25 healthy controls (CTR) matched by age, gender, education, and socioeconomic status. An exhaustive NPS battery was used to assess cognitive domains (attention, executive functions, fluid intelligence, memory, language and social cognition). We complemented this assessment with structural (MRI) and functional (fMRI) neuroimaging data. We found that executive function and attention impairments could be explained by the administration route of cocaine, with strongest impairments for the SCD group. SCD also presented reduced grey matter density relative to ICD and CTR in the bilateral caudate, a key area for executive and attentional function. Functional connectivity between left caudate and inferior frontal regions mediated the association between brain structure and behavioral performance. Our results highlight the relevance of assessing the route of administration of stimulants, both in clinical and research settings.

The neurocognitive basis of morphological processing in typical and impaired readers.

Morphological awareness, or sensitivity to units of meaning, is an essential component of reading comprehension development. Current neurobiological models of reading and dyslexia have largely been built upon phonological processing models, yet reading for meaning is as essential as reading for sound. To fill this gap, the present study explores the relation between children's neural organization for morphological awareness and successful reading comprehension in typically developing and impaired readers. English-speaking children ages 6-11 (N = 97; mean age = 8.6years, 25% reading impaired) completed standard literacy assessments as well as an auditory morphological awareness task during functional near-infrared spectroscopy (fNIRS) neuroimaging, which included root (e.g., PERSON + al) and derivational (e.g., quick + LY) morphology. Regression analyses revealed that children's morphological awareness predicted unique variance in reading comprehension above and beyond demographic factors, vocabulary knowledge, and decoding ability. Neuroimaging analyses further revealed that children with stronger reading comprehension showed greater engagement of brain regions associated with integrating sound and meaning, including left inferior frontal, middle temporal, and inferior parietal regions. This effect was especially notable for the derivational morphology condition that involved manipulating more analytically demanding and semantically abstract units (e.g., un-, -ly, -ion). Together, these findings suggest that successful reading comprehension, and its deficit in dyslexia, may be related to the ability to manipulate morpho-phonological units of word meaning and structure. These results inform theoretical perspectives on literacy and children's neural architecture for learning to read.

Spectrum of clinical and FDG-PET patterns of patients with frontotemporal dementia (FTD) in a tertiary care hospital

Introduction. Frontotemporal dementia (FTD) is a common cause of cognitive impairment, behavioral changes and language deficits. in this study we assessed the clinical and FDG-PET characteristics of our patients and compared them with available international and Indian data on FTD. Methods. All patients were evaluated with a neuropsychological battery followed by 18F-FDG-PET scan, in addition to all necessary dementia work-up. Results. 15 FTD patients (m:f = 11:4) had a mean age of presentation of 67.4 (8.6) years, with a mean interval of 1.7 (0.7) years from the symptom onset to diagnosis. those with 10 or less years of education had an earlier presentation. a positive family history was present in 20%. The mean MMSE score was 18.8 (4.6). Disinhibition was the most common symptom seen in 60%. Apathy was less frequently noted. FDG-PET scan showed predominantly anterior cingulate and anterior temporal hypometabolism, with asymmetry in 67%. 2 cases diagnosed as fvAD had a revised diagnosis of bvFTD after FDG-PET scan. 1 patient of nfvPPA was mute at presentation with a history of agrammatism with hypometabolism in left inferior frontal and superior temporal regions. Conclusions. There were significant variations compared to international/Western literature, with later age of presentation, shorter interval from onset to presentation, lower MMSE scores, with disinhibition rather than apathy as the commonest symptom. FDG-PET showed similar areas of involvement but with less extensive hypometabolism compared to other studies with a lesser frequency of asymmetry. FDG-PET scan is a useful adjunct for evaluation of FTD patients.