Dorsal Route Research Articles

Shared and distinct routes in speech and gesture imitation: Evidence from stroke

Dual-route models of high-level (praxis) actions distinguish between an “indirect” semantic route mediating meaningful gesture imitation, and a “direct” sensory-motor route mediates meaningless gesture imitation. Similarly, dual-route language models distinguish between an indirect route mediating production and repetition of words, and a direct route mediating non-word repetition. Although aphasia and limb apraxia frequently co-occur following left-hemisphere cerebrovascular accident (LCVA), it is unclear which aspects of these functional-neuroanatomic dual-route architectures are shared across praxis and language domains. This study focused on gesture imitation to test the hypothesis that semantic information (and portions of the indirect route) are shared across domains, whereas two distinct dorsal routes mediate sensory-motor mapping. Forty chronic LCVA and 17 neurotypical controls completed semantic memory and language tasks and imitated 3 types of gesture stimuli: (1) labeled/“named” meaningful, (2) unnamed meaningful, and (3) meaningless gestures. The comparison of accuracy between meaningless versus unnamed meaningful gestures examined the benefits of semantic information, while the comparison of unnamed meaningful versus named meaningful imitation examined additional benefits of linguistic cueing. Mixed-effects models examined group by task interaction effects on gesture ability. We found that for patients with LCVA, unnamed meaningful gestures were imitated more accurately than meaningless gestures, suggesting that semantic information was beneficial, but there was no benefit of labeling. Reduced benefit of semantic information on gesture accuracy was associated with lesions to inferior frontal and posterior temporal regions as well as semantic memory performance on a pictorial (non-gesture) task. In contrast, there was no relationship between meaningless gesture imitation and nonword repetition, indicating that measures of direct route performance are not associated across language and action. These results provide preliminary evidence that portions of the indirect semantic route are shared across the language and action domains, while two direct sensory-motor mapping routes mediate word repetition and gesture imitation.

Primary oral vaccination followed by a vaginal pull protects mice against genital HSV-2 infection.

HSV-2 infected more than 491 million people aged 15-49 world-wide in 2016. The morbidity associated with recurrent infections and the increased risk of HIV infection make this a major health problem. To date there is no effective vaccine. Because HSV-2 ascends to the dorsal route ganglion within 12-18 hours of infection, an effective vaccine will need to elicit a strong local resident CD8+ T cell response to prevent the infection from becoming life-long. Using a mouse model we investigated the potential of oral immunization with a novel lipid adjuvant (LiporaleTM) followed by local vaginal application of an inflammatory agents to protect against primary HSV-2 infections. Oral vaccination of mice with live-attenuated HSV-2 in LiporaleTM followed by vaginal application of DNFB or CXCL9/10 led to recruitment of tissue-resident CD8+ memory cells into the genital epithelia. This prime and pull vaccination strategy provided complete protection against wild-type HSV-2 challenge and prevented viral dissemination to the spinal cords. Activation of mucosal immunity by oral immunization, combined with induction of transient local genital inflammation can recruit long-lived tissue resident CD8+ T cells into the genital epithelium, providing significant protection against primary HSV-2 infection. This article is protected by copyright. All rights reserved.

Neural basis of visuospatial tests in behavioral variant frontotemporal dementia

BackgroundRecent models of visuospatial functioning suggest the existence of three main circuits emerging from the dorsal (“where”) route: parieto-prefrontal pathway, parieto-premotor, and parieto-medial temporal. Neural underpinnings of visuospatial task performance and the sparing of visuospatial functioning in bvFTD are unclear. We hypothesized different neural and cognitive mechanisms in visuospatial tasks performance in bvFTD and AD.MethodsTwo hundred and sixteen participants were enrolled for this study: 72 patients with bvFTD dementia and 144 patients with AD. Visual Object and Space Perception Battery Position Discrimination and Number Location (VOSP-PD and VOSP-NL) and Rey-Osterrieth Complex Figure (ROCF) were administered to examine visuospatial functioning, together with a comprehensive neuropsychological battery. FDG-PET was acquired to evaluate brain metabolism. Voxel-based brain mapping analyses were conducted to evaluate the brain regions associated with visuospatial function in bvFTD and AD.ResultsPatients with AD performed worst in visuospatial tasks in mild dementia, but not at prodromal stage. Attention and executive functioning tests showed higher correlations in bvFTD than AD with ROCF, but not VOSP subtests. Visuospatial performance in patients with bvFTD was associated with bilateral frontal regions, including the superior and medial frontal gyri, supplementary motor area, insula and middle cingulate gyrus.ConclusionThese findings support the role of prefrontal and premotor regions in visuospatial processing through the connection with the posterior parietal cortex and other posterior cortical regions. Visuospatial deficits should be interpreted with caution in patients with bvFTD, and should not be regarded as hallmarks of posterior cortical dysfunction.

Investigating Post-transcriptional Mechanism of Neuropathic Pain

Neuropathic pain is a chronic condition which can arise following damage to the somatosensory system and often involves both hyperalgesia and allodynia. The molecular mechanisms of neuropathic pain remain incompletely understood but require enduring alterations in specific gene programs and protein synthesis affecting neuronal signaling and excitability. We investigate non-coding RNA and RNA-binding protein regulatory pathways in impacting hyperalgesia and neuropathic pain using the mouse spared nerve injury model. Nerve injury alters the expression of many miRNAs, including the highly conserved let-7 family miRNAs, which repress pro-growth mRNAs and are implicated in axon growth, neuronal plasticity, and brain circuit development. The Lin28 RNA binding protein can prevent maturation of let-7 precursor RNAs; consequently, increased Lin28 signaling promotes pro-growth gene expression. The regulation and potential roles of Lin28/let-7 pathway in neuropathic pain remain largely unexplored. In preliminary data, we find that Lin28a loss of function in some, but not other, sensory neuron populations can result in a deficit in mechanical hypersensitivity post-injury. In the SNI mouse model, we evaluate molecular mechanisms underlying pain using single molecule detection. A specific RNA imaging assay, RNAscope in situ hybridization (ISH), is used to amplify single RNA target signals in fixed tissues to allow mapping of the spatiotemporal patterns and cell type specificity of changes. We find that Lin28 mRNAs are elevated in classes of injured neurons relative to uninjured neurons in dorsal route ganglia (DRG) which are ipsilateral at early, 3 day, timepoints post-SNI surgery. In contrast, Lin28 mRNAs are highly elevated following a more protracted time courses post-surgery in the compartment of injured neuronal processes. The spatiotemporal differences in Lin28 mRNA levels across compartments of the nervous system following nerve injury could indicate potential trafficking or local stabilization of Lin28 mRNAs and are the subject of ongoing investigations. Grant support from NIH NS103974.

Structural connectivity in ventral language pathways characterizes non-verbal autism

Language capacities in autism spectrum disorders (ASD) range from normal scores on standardized language tests to absence of functional language in a substantial minority of 30% of individuals with ASD. Due to practical difficulties of scanning at this severe end of the spectrum, insights from MRI are scarce. Here we used manual deterministic tractography to investigate, for the first time, the integrity of the core white matter tracts defining the language connectivity network in non-verbal ASD (nvASD): the three segments of the arcuate (AF), the inferior fronto-occipital (IFOF), the inferior longitudinal (ILF) and the uncinate (UF) fasciculi, and the frontal aslant tract (FAT). A multiple case series of nine individuals with nvASD were compared to matched individuals with verbal ASD (vASD) and typical development (TD). Bonferroni-corrected repeated measure ANOVAs were performed separately for each tract—Hemisphere (2:Left/Right) × Group (3:TD/vASD/nvASD). Main results revealed (i) a main effect of group consisting in a reduction in fractional anisotropy (FA) in the IFOF in nvASD relative to TD; (ii) a main effect of group revealing lower values of radial diffusivity (RD) in the long segment of the AF in nvASD compared to vASD group; and (iii) a reduced volume in the left hemisphere of the UF when compared to the right, in the vASD group only. These results do not replicate volumetric differences of the dorsal language route previously observed in nvASD, and instead point to a disruption of the ventral language pathway, in line with semantic deficits observed behaviourally in this group.

Structural white matter connectometry of reading and dyslexia

Current views on the neural network subserving reading and its deficits in dyslexia rely largely on evidence derived from functional neuroimaging studies. However, understanding the structural organization of reading and its aberrations in dyslexia requires a hodological approach, studies of which have not provided consistent findings. Here, we adopted a whole brain hodological approach and investigated relationships between structural white matter connectivity and reading skills and phonological processing in a cross-sectional study of 44 adults using individual local connectome matrix from diffusion MRI data. Moreover, we performed quantitative anisotropy aided differential tractography to uncover structural white matter anomalies in dyslexia (23 dyslexics and 21 matched controls) and their correlation to reading-related skills. The connectometry analyses indicated that reading skills and phonological processing were both associated with corpus callosum (tapetum), forceps major and minor, as well as cerebellum bilaterally. Furthermore, the left dorsal and right thalamic pathways were associated with phonological processing. Differential tractography analyses revealed structural white matter anomalies in dyslexics in the left ventral route and bilaterally in the dorsal route compared to the controls. Connectivity deficits were also observed in the corpus callosum, forceps major, vertical occipital fasciculus and corticostriatal and thalamic pathways. Altered structural connectivity in the observed differential tractography results correlated with poor reading skills and phonological processing. Using a hodological approach, the current study provides novel evidence for the extent of the reading-related connectome and its aberrations in dyslexia. The results conform current functional neuroanatomical models of reading and developmental dyslexia but provide novel network-level and tract-level evidence on structural connectivity anomalies in dyslexia, including the vertical occipital fasciculus.

Analysis on the route of conception vessel and governor vessel in Huangdi Neijing (The Yellow Emperor's Inner Classic)

On the base of the analysis on the original text in Huangdi Neijing (The Yellow Emperor ¢s Inner Classic) and in association with the meridian tracing experiment results in transparent fish, rats and human body, the routes of conception vessel and governor vessel were recognized de novo. The starting site of conception vessel has been described as "the center of uterus" and "the inferior part of Zhongji (CV 3)", which refer to the same region. The running course of conception vessel includes 3 routes, named the deep abdominal route, the deep dorsal route and the superficial abdominal route. The governor vessel starts at Qugu (CV 2) on the pubis and its running course includes 4 routes, named the buttock-spine ascending route, the head-back descending route, the abdomen-face ascending route and the head-back midline route. Both the conception vessel and the governor vessel distribute on the anterior and the posterior aspects of the trunk, head and face, but they are in deep and shallow layers respectively, forming two cycles internally and externally. Such recognition is really not the pattern, known by the people, that conception vessel distributes in the front, while the governor vessel on the back.

Vasomotor Function of Radial Artery after Conventional Transradial Approach and Dorsal (Snuff Box) Approach

The trans outspread way to deal with cardiovascular catheterization has numerous benefits over the transfemoral approach and is progressively being utilized for both analytic coronary angiography and percutaneous coronary intercession. This investigation is intended to gauge the stream intervened expansion of the outspread supply route preceding and after the transradial approach for coronary angiography utilizing traditional transradial approach and dorsal transradial approach through snuff box. Patient and strategies: This is a planned observational investigation included 100 patients for transradial approach for coronary angiography. Patients were separated into two groups:Group (I): through ordinary transradial approach Group (II): through dorsal snuff box approach. All patients went through spiral conduit B-mode ultrasound imaging, and stream interceded dilatation (FMD) was utilized preceding catheterization and inside 10 days following the catheterization.Diameter of the outspread vein was estimated by high-goal outer vascular ultrasound because of an increment in blood stream (causing shear-stress) Results: A critical distinction between the ordinary and dorsal snuff box course in spiral corridor width after FMD pre and post strategy (estimated inside 10 days follow up of the patient ) with a pre-procedural mean breadth 0.275± 0.619mm (2.92 ± 0.747 versus 2.59 ± 0.491in traditional and dorsal gathering separately, P =0.010). There were ten instances of outspread course impediment at multi week follow up, 2 and 8 patients in traditional (4%) and dorsal routes(16%) individually, P=0.046 in any case, none of them was suggestive. We regularly utilized either IV or intra-blood vessel heparin for prophylaxis of spiral corridor impediment. End: Distal spiral methodology through the anatomical snuff box is arising as a practical and safe option in contrast to traditional one with a few benefits.

Taking the sublexical route: brain dynamics of reading in the semantic variant of primary progressive aphasia.

Reading aloud requires mapping an orthographic form to a phonological one. The mapping process relies on sublexical statistical regularities (e.g. 'oo' to |uː|) or on learned lexical associations between a specific visual form and a series of sounds (e.g. yacht to/jɑt/). Computational, neuroimaging, and neuropsychological evidence suggest that sublexical, phonological and lexico-semantic processes rely on partially distinct neural substrates: a dorsal (occipito-parietal) and a ventral (occipito-temporal) route, respectively. Here, we investigated the spatiotemporal features of orthography-to-phonology mapping, capitalizing on the time resolution of magnetoencephalography and the unique clinical model offered by patients with semantic variant of primary progressive aphasia (svPPA). Behaviourally, patients with svPPA manifest marked lexico-semantic impairments including difficulties in reading words with exceptional orthographic to phonological correspondence (irregular words). Moreover, they present with focal neurodegeneration in the anterior temporal lobe, affecting primarily the ventral, occipito-temporal, lexical route. Therefore, this clinical population allows for testing of specific hypotheses on the neural implementation of the dual-route model for reading, such as whether damage to one route can be compensated by over-reliance on the other. To this end, we reconstructed and analysed time-resolved whole-brain activity in 12 svPPA patients and 12 healthy age-matched control subjects while reading irregular words (e.g. yacht) and pseudowords (e.g. pook). Consistent with previous findings that the dorsal route is involved in sublexical, phonological processes, in control participants we observed enhanced neural activity over dorsal occipito-parietal cortices for pseudowords, when compared to irregular words. This activation was manifested in the beta-band (12-30 Hz), ramping up slowly over 500 ms after stimulus onset and peaking at ∼800 ms, around response selection and production. Consistent with our prediction, svPPA patients did not exhibit this temporal pattern of neural activity observed in controls this contrast. Furthermore, a direct comparison of neural activity between patients and controls revealed a dorsal spatiotemporal cluster during irregular word reading. These findings suggest that the sublexical/phonological route is involved in processing both irregular and pseudowords in svPPA. Together these results provide further evidence supporting a dual-route model for reading aloud mediated by the interplay between lexico-semantic and sublexical/phonological neurocognitive systems. When the ventral route is damaged, as in the case of neurodegeneration affecting the anterior temporal lobe, partial compensation appears to be possible by over-recruitment of the slower, serial attention-dependent, dorsal one.

The effects of exogenous melatonin administration on bone in ovariectomized and pinealectomized rats

Introduction: One of the most common metabolic bone disease is postmenopausal osteoporosis. There is data that pineal melatonin (MLT) is decreased with age and that menopause is correlate with a substantial decrease in melatonin secretion and increased rate of pineal gland calcification. Because of this, in the present study, the authors aimed to assess pinealectomy-induced melatonin deficiency in menopause which may be a contributing factor in the development of postmenopausal osteoporosis. Materials and Methods: A total of 49 young Wistar-Albino rats were included in the study. Some groups underwent bilateral ovariectomy (OVX) via the dorsal route, and pinealectomy (PX) was performed with Kuszack and Rodin method. Following PX and OVX, selected groups were given a dose of 5 mg /kg/day injected intraperitoneally. The authors evaluated bone mineral density (BMD) of the femur by dual-energy X-ray absorptiometry. The BMD of femur named as proximal 1/3 (RI), middle 1/3 (R2), distal 1/3 (R3), and total (R4). Results: Compared with the sham group, PX + MLT group had significantly higher BMD values at R3 subregion. There is no statistically significant relationship between PX+OVX group and PX+OVX+MLT group at subregions. Compared with the OVX + MLT group, PX+OVX+MLT group had significantly higher BMD values at R1, R3, and R4 subregions. Conclusion: PX significantly increases BMD at R3 subregion, but its not reversed by exogenous MLT administration. OVX cancelled the effects of PX with respect to increases in the levels of reached bone mass. Exogenous MLT administration to OVX and PX group did not increase BMD values.

Dorsal and ventral visual streams: Typical and atypical development

ABSTRACTThe literature on visuospatial processing describes two distinct pathways within the brain: a dorsal route extending from the visual cortex into the parietal lobes that is critical for spatial processing and a ventral route extending from the visual cortex into the temporal lobes that is critical for form perception. These visual streams appear to differ in their developmental trajectories and their vulnerabilities to diverse neurodevelopmental conditions. The present work aims to investigate development and vulnerability in two aspects of dorsal and ventral visual-stream function, namely attention to location and attention to identity. In Study 1, we compare typically-developing (TD) youth aged 9 to 16 years with young adults aged 18 to 22 years on computerized location and identity tasks. In Study 2, we compare children and adolescents who have congenital hypothyroidism (CH), a pediatric endocrine disorder, with age-matched TD controls on the same tasks. The results from Study 1 show that the youths were less accurate than the adults at judging identity, whereas both groups were equally accurate at judging location. The results from Study 2 show that the youths with CH were slower but not less accurate than the TD youths in making both identity and location judgments. The results are interpreted as signifying later development of ventral (identity) stream functions compared to dorsal (location) but equal vulnerability of both functions in CH.

IWGDF guidance on the diagnosis and management of foot infections in persons with diabetes.

RecommendationsClassification/diagnosis Diabetic foot infection must be diagnosed clinically, based on the presence of local or systemic signs or symptoms of inflammation (strong; low). Assess the severity of any diabetic foot infection using the Infectious Diseases Society of America/International Working Group on the Diabetic Foot classification scheme (strong; moderate). Osteomyelitis For an infected open wound, perform a probe‐to‐bone test; in a patient at low risk for osteomyelitis, a negative test largely rules out the diagnosis, while in a high‐risk patient, a positive test is largely diagnostic (strong; high). Markedly elevated serum inflammatory markers, especially erythrocyte sedimentation rate, are suggestive of osteomyelitis in suspected cases (weak; moderate). A definite diagnosis of bone infection usually requires positive results on microbiological (and, optimally, histological) examinations of an aseptically obtained bone sample, but this is usually required only when the diagnosis is in doubt or determining the causative pathogen's antibiotic susceptibility is crucial (strong; moderate). A probable diagnosis of bone infection is reasonable if there are positive results on a combination of diagnostic tests, such as probe‐to‐bone, serum inflammatory markers, plain X‐ray, magnetic resonance imaging (MRI) or radionuclide scanning (strong; weak). Avoid using results of soft tissue or sinus tract specimens for selecting antibiotic therapy for osteomyelitis as they do not accurately reflect bone culture results (strong; moderate). Obtain plain X‐rays of the foot in all cases of non‐superficial diabetic foot infection (strong; low). Use MRI when an advanced imaging test is needed for diagnosing diabetic foot osteomyelitis (strong; moderate). When MRI is not available or contraindicated, consider a white blood cell‐labelled radionuclide scan, or possibly single‐photon emission computed tomography (CT) and CT (SPECT/CT) or fluorine‐18‐fluorodeoxyglucose positron emission tomography/CT scans (weak; moderate). Assessing severity At initial evaluation of any infected foot, obtain vital signs and appropriate blood tests, debride the wound and probe and assess the depth and extent of the infection to establish its severity (strong; moderate). At initial evaluation, assess arterial perfusion and decide whether and when further vascular assessment or revascularization is needed (strong; low). Microbiological considerations Obtain cultures, preferably of a tissue specimen rather than a swab, of infected wounds to determine the causative microorganisms and their antibiotic sensitivity (strong; high). Do not obtain repeat cultures unless the patient is not clinically responding to treatment, or occasionally for infection control surveillance of resistant pathogens (strong; low). Send collected specimens to the microbiology laboratory promptly, in sterile transport containers, accompanied by clinical information on the type of specimen and location of the wound (strong; low). Surgical treatment Consult a surgical specialist in selected cases of moderate, and all cases of severe, diabetic foot infection (weak; low). Perform urgent surgical interventions in cases of deep abscesses, compartment syndrome and virtually all necrotizing soft tissue infections (strong; low). Consider surgical intervention in cases of osteomyelitis accompanied by spreading soft tissue infection, destroyed soft tissue envelope, progressive bone destruction on X‐ray or bone protruding through the ulcer (strong; low). Antimicrobial therapy While virtually all clinically infected diabetic foot wounds require antimicrobial therapy, do not treat clinically uninfected wounds with antimicrobial therapy (Strong; Low) Select specific antibiotic agents for treatment based on the likely or proven causative pathogens, their antibiotic susceptibilities, the clinical severity of the infection, evidence of efficacy of the agent for diabetic foot infection and costs (strong; moderate). A course of antibiotic therapy of 1–2 weeks is usually adequate for most mild and moderate infections (strong; high). Administer parenteral therapy initially for most severe infections and some moderate infections, with a switch to oral therapy when the infection is responding (strong; low). Do not select a specific type of dressing for a diabetic foot infection with the aim of preventing an infection or improving its outcome (strong; high). For diabetic foot osteomyelitis, we recommend 6 weeks of antibiotic therapy for patients who do not undergo resection of infected bone and no more than a week of antibiotic treatment if all infected bone is resected (strong; moderate). We suggest not using any adjunctive treatments for diabetic foot infection (weak; low). When treating a diabetic foot infection, assess for use of traditional remedies and previous antibiotic use and consider local bacterial pathogens and their susceptibility profile (strong; low).

Allocentric coding in ventral and dorsal routes during real-time reaching: Evidence from imaging-guided multi-site brain stimulation

Recent evidence has revealed an advantage for movements to last target positions in a structured visual display, suggesting a mediating role of allocentric, in addition to egocentric, information in goal-directed reaching. This notion is accommodated by the recently updated perception-action model (Milner and Goodale, 2008), which postulates functional roles of ventral and dorsal neural areas in allocentric coding. In the present study, we used imaging-guided multi-site continuous theta burst stimulation (cTBS) over regions of the ventral and dorsal processing streams to unravel their functional contribution on visually guided reaching in two display conditions: the “egocentric” condition where the target appeared in an empty display and the “allocentric” condition where the target appeared in a structured display with placeholders marking possible target locations. Cortical sites for cTBS were identified individually for each participant via coregistration with magnetic resonance scans. Results indicated that cTBS in the egocentric condition did not affect movement time, but cTBS in the allocentric condition modulated movement time contingent on stimulation site and target position. In particular, cTBS over the lateral occipital cortex (part of the ventral stream) and over the angular gyrus (part of the dorsal stream) eliminated the last-target advantage by slowing down reaching to the salient last target position. cTBS over the superior parietal occipital cortex did not affect the last-target advantage. These outcomes provide the first causal evidence for allocentric coding in ventral and dorsal routes during real-time reaching, thereby supporting the updated perception-action model.

Double-letter processing in surface dyslexia and dysgraphia following a left temporal lesion: A multimodal neuroimaging study

Neuropsychological data about acquired impairments in reading and writing provide a strong basis for the theoretical framework of the dual-route models. The present study explored the functional neuroanatomy of the reading and spelling processing system. We describe the reading and writing performance of patient CF, an Italian native speaker who developed an extremely selective reading and spelling deficit (his spontaneous speech, oral comprehension, repetition and oral picture naming were almost unimpaired) in processing double letters associated with surface dyslexia and dysgraphia, following a tumor in the left temporal lobe. In particular, the majority of CF's errors in spelling were phonologically plausible substitutions, errors concerning letter numerosity of consonants, and syllabic phoneme-to-grapheme conversion (PGC) errors. A similar pattern of impairment also emerged in his reading behavior, with a majority of lexical stress errors (the only possible type of surface reading errors in the Italian language, due the extreme regularity of print-to-sound correspondence).CF's neuropsychological profile was combined with structural neuroimaging data, fiber tracking, and functional maps and compared to that of healthy control participants. We related CF's deficit to a dissociation between impaired ventral/lexical route (as evidenced by a fractional anisotropy – FA decrease along the inferior fronto-occipital fasciculus – IFOF) and relatively preserved dorsal/phonological route (as evidenced by a rather full integrity of the superior longitudinal fasciculus – SLF). In terms of functional processing, the lexical-semantic ventral route network was more activated in controls than in CF, while the network supporting the dorsal route was shared by CF and the control participants. Our results are discussed within the theoretical framework of dual-route models of reading and spelling, emphasize the importance of the IFOF both in lexical reading and spelling, and offer a better comprehension of the neurological and functional substrates involved in written language and, in particular, in surface dyslexia and dysgraphia and in doubling/de-doubling consonant sounds and letters.

Evaluating proposed dorsal and ventral route functions in speech perception and phonological short-term memory: Evidence from aphasia

Evaluating proposed dorsal and ventral route functions in speech perception and phonological short-term memory: Evidence from aphasia

Adapting Dynamic Causal Modeling to Investigate the Cooperation between the Ventral and Dorsal Routes of Reading Neural Network

Adapting Dynamic Causal Modeling to Investigate the Cooperation between the Ventral and Dorsal Routes of Reading Neural Network

The left inferior fronto-occipital fasciculus subserves language semantics: a multilevel lesion study.

Consequential works in cognitive neuroscience have led to the formulation of an interactive dual-stream model of language processing: the dorsal stream may process the phonological aspects of language, whereas the ventral stream may process the semantic aspects of language. While it is well-accepted that the dorsal route is subserved by the arcuate fasciculus, the structural connectivity of the semantic ventral stream is a matter of dispute. Here we designed a longitudinal study to gain new insights into this central but controversial question. Thirty-one patients harboring a left diffuse low-grade glioma—a rare neurological condition that infiltrates preferentially white matter associative pathways—were assessed with a prototypical task of language (i.e. verbal fluency) before and after surgery. All were operated under local anesthesia with a cortical and subcortical brain mapping—enabling to identify and preserve eloquent structures for language. We performed voxel-based lesion-symptom (VLSM) analyses on pre- and postoperative behavioral data. Preoperatively, we found a significant relationship between semantic fluency scores and the white matter fibers shaping the ventro-lateral connectivity (P < 0.05 corrected). The statistical map was found to substantially overlap with the spatial position of the inferior fronto-occipital fasciculus (IFOF) (37.7%). Furthermore, a negative correlation was observed between semantic fluency scores and the infiltration volumes in this fasciculus (r = -0.4, P = 0.029). Postoperatively, VLSM analyses were inconclusive. Taken as a whole and when combined with the literature data, our findings strengthen the view that the IFOF plays an essential role in semantic processing and may subserve the direct ventral pathway of language.

Modeling activation and effective connectivity of VWFA in same script bilinguals.

Previous neuroimaging research revealed a small area in the inferior occipito-temporal cortex (VWFA), which seems to be involved in recognition of written words. The specialized response of the VWFA to words could result from repeated exposure to print in the course of functional fine-tuning of the brain. Research with bilingual speakers holds promise in helping to reveal response properties of the VWFA by assessing its sensitivity to language proficiency, word-form similarity, and meaning overlap across two languages. Using fMRI, we compared VWFA activity for cognate and homograph prime-target pairs in a group of fluent Spanish-English speakers. Cognates share form and meaning in two languages, while homographs only share form. Relative to baseline, the VWFA showed repetition suppression to pairs of homographs, but not to pairs of cognates, suggesting that this area is sensitive to word meaning. The different response to cognates and homographs was only observed when English was the prime language and Spanish was the target language. To help explain this result we compared patterns of effective connectivity between the VWFA and other parts of the reading network implicated in semantic and phonological processing. Our neural models showed that English targets engaged a direct ventral route from the VWFA to the frontal lobe and Spanish targets engaged an indirect dorsal route. Considering that frontal cortex has been implicated in semantic processing, a direct connection to this area could signal a fast and automatic access to meaning and would facilitate early semantic influences in visual word recognition.

AB0691 Ultrasonography signs in metacarpophalangeal and metatarsophalangeal joints in children suffering from juvenile idiopathic arthritis in morocco : comparison of clinical evaluation

ObjectivesThe objective of our study was to search the ultrasonography afflictions metacarpophalangeal and metatarsophalangeal joints notably ultrasonography synovitis, the intra articular liquid accumulations, the cartilaginous vascularisation, bone erosion and to...

Automatic Phoneme Category Selectivity in the Dorsal Auditory Stream

Debates about motor theories of speech perception have recently been reignited by a burst of reports implicating premotor cortex (PMC) in speech perception. Often, however, these debates conflate perceptual and decision processes. Evidence that PMC activity correlates with task difficulty and subject performance suggests that PMC might be recruited, in certain cases, to facilitate category judgments about speech sounds (rather than speech perception, which involves decoding of sounds). However, it remains unclear whether PMC does, indeed, exhibit neural selectivity that is relevant for speech decisions. Further, it is unknown whether PMC activity in such cases reflects input via the dorsal or ventral auditory pathway, and whether PMC processing of speech is automatic or task-dependent. In a novel modified categorization paradigm, we presented human subjects with paired speech sounds from a phonetic continuum but diverted their attention from phoneme category using a challenging dichotic listening task. Using fMRI rapid adaptation to probe neural selectivity, we observed acoustic-phonetic selectivity in left anterior and left posterior auditory cortical regions. Conversely, we observed phoneme-category selectivity in left PMC that correlated with explicit phoneme-categorization performance measured after scanning, suggesting that PMC recruitment can account for performance on phoneme-categorization tasks. Structural equation modeling revealed connectivity from posterior, but not anterior, auditory cortex to PMC, suggesting a dorsal route for auditory input to PMC. Our results provide evidence for an account of speech processing in which the dorsal stream mediates automatic sensorimotor integration of speech and may be recruited to support speech decision tasks.