Posterior Middle Temporal Gyrus Research Articles

Perception drives production across sensory modalities: A network for sensorimotor integration of visual speech

Sensory information is critical for movement control, both for defining the targets of actions and providing feedback during planning or ongoing movements. This holds for speech motor control as well, where both auditory and somatosensory information have been shown to play a key role. Recent clinical research demonstrates that individuals with severe speech production deficits can show a dramatic improvement in fluency during online mimicking of an audiovisual speech signal suggesting the existence of a visuomotor pathway for speech motor control. Here we used fMRI in healthy individuals to identify this new visuomotor circuit for speech production. Participants were asked to perceive and covertly rehearse nonsense syllable sequences presented auditorily, visually, or audiovisually. The motor act of rehearsal, which is prima facie the same whether or not it is cued with a visible talker, produced different patterns of sensorimotor activation when cued by visual or audiovisual speech (relative to auditory speech). In particular, a network of brain regions including the left posterior middle temporal gyrus and several frontoparietal sensorimotor areas activated more strongly during rehearsal cued by a visible talker versus rehearsal cued by auditory speech alone. Some of these brain regions responded exclusively to rehearsal cued by visual or audiovisual speech. This result has significant implications for models of speech motor control, for the treatment of speech output disorders, and for models of the role of speech gesture imitation in development.

Automatic and Controlled Semantic Retrieval: TMS Reveals Distinct Contributions of Posterior Middle Temporal Gyrus and Angular Gyrus.

We demonstrate a novel functional dissociation between the angular gyrus (AG) and posterior middle temporal gyrus (pMTG) in conceptual processing. These sites are often coactivated during neuroimaging studies using semantic tasks, but their individual contributions are unclear. Using transcranial magnetic stimulation and tasks designed to assess different aspects of semantics (item identity and thematic matching), we tested two alternative theoretical accounts. Neither site showed the pattern expected for a "thematic hub" (i.e., a site storing associations between concepts) since stimulation disrupted both tasks. Instead, the data indicated that pMTG contributes to the controlled retrieval of conceptual knowledge, while AG is critical for the efficient automatic retrieval of specific semantic information.

Voxel-Based Lesion Symptom Mapping of Coarse Coding and Suppression Deficits in Patients With Right Hemisphere Damage.

This study examined right hemisphere (RH) neuroanatomical correlates of lexical-semantic deficits that predict narrative comprehension in adults with RH brain damage. Coarse semantic coding and suppression deficits were related to lesions by voxel-based lesion symptom mapping. Participants were 20 adults with RH cerebrovascular accidents. Measures of coarse coding and suppression deficits were computed from lexical decision reaction times at short (175 ms) and long (1000 ms) prime-target intervals. Lesions were drawn on magnetic resonance imaging images and through normalization were registered on an age-matched brain template. Voxel-based lesion symptom mapping analysis was applied to build a general linear model at each voxel. Z score maps were generated for each deficit, and results were interpreted using automated anatomical labeling procedures. A deficit in coarse semantic activation was associated with lesions to the RH posterior middle temporal gyrus, dorsolateral prefrontal cortex, and lenticular nuclei. A maintenance deficit for coarsely coded representations involved the RH temporal pole and dorsolateral prefrontal cortex more medially. Ineffective suppression implicated lesions to the RH inferior frontal gyrus and subcortical regions, as hypothesized, along with the rostral temporal pole. Beyond their scientific implications, these lesion-deficit correspondences may help inform the clinical diagnosis and enhance decisions about candidacy for deficit-focused treatment to improve narrative comprehension in individuals with RH damage.

Surgical challenges for lateral ventricle meningiomas: A consecutive series of 21 patients.

Lateral ventricular meningiomas (LVMs) are especially rare, and they often remain "silent" until they become very large. Several surgical approaches exist, but the optimal surgical strategy for them remains a challenge. The incidence, clinical features, radiological manifestations, pathological findings, and especially the surgical strategy in 21 patients with LVMs were analyzed retrospectively. The mean age of patients was 42.7 years (range, 17 to 78 years). Raised intracranial pressure was the main presenting symptom. The definite diagnosis of LVMs in most cases was made by computed tomography (CT) or magnetic resonance imaging (MRI). Six patients were subjected to plain CT scans, 15 to contrast MR scans, and 4 to a magnetic resonance angiogram (MRA). Large tumors were seen in most cases with an average diameter of more than 4.3 cm. Of the 21 cases of LVMs in our series, LVMs were resected in 16 cases via a posterior parieto-occipital transcortical approach, 2 cases via a transcallosal approach, and 3 cases via a posterior middle temporal gyrus approach. In 8 out of 21 cases, the tumors were located in the left lateral ventricle. The gross total surgical excision was achieved in 18 (86%) patients, and all LVMs were pathologically confirmed to be benign. Nine patients were followed up (range: 11 months-4.6 years). Eight (88.9%) cases obtained good recovery and one (11.1%) obtained moderate disability. Four approaches are available for the surgical treatment of LVMs. The choice of surgical approaches depends on tumor location, laterality, size and extension, and the function of the brain must be taken into account. Intracapsular resection and piecemeal resection of LVMs can be safely and easily performed. Preoperative MRA scan is important to know the feeder of LVMs and peripheral blood supply.

Ventral simultanagnosia and prosopagnosia for unfamiliar faces due to a right posterior superior temporal sulcus and angular gyrus lesion

We report a patient with ventral simultanagnosia, prosopagnosia for “unfamiliar faces” (dorsal prosopagnosia), spatial agraphia, and constructional disorder, particularly on the left spatial side, due to a lesion in the right posterior superior and middle temporal gyri and angular gyrus. The patient showed impairment of fundamental visual and visuospatial recognition, such as in object size, configuration, and horizontal point location, which probably underlay the mechanism of simultanagnosia and prosopagnosia. This case also suggests that the coexistence of simultanagnosia and prosopagnosia results from a right hemispheric insult, and damage to the temporoparietal area interrupts the incorporation of spatial information into object recognition. This disconnection of information flow, together with impaired object recognition per se, may impair the parallel processing of multiple objects, leading to object-by-object or part-by-part recognition.

Separate Brain Circuits Support Integrative and Semantic Priming in the Human Language System

Semantic priming is a crucial phenomenon to study the organization of semantic memory. A novel type of priming effect, integrative priming, has been identified behaviorally, whereby a prime word facilitates recognition of a target word when the 2 concepts can be combined to form a unitary representation. We used both functional and anatomical imaging approaches to investigate the neural substrates supporting such integrative priming, and compare them with those in semantic priming. Similar behavioral priming effects for both semantic (Bread-Cake) and integrative conditions (Cherry-Cake) were observed when compared with an unrelated condition. However, a clearly dissociated brain response was observed between these 2 types of priming. The semantic-priming effect was localized to the posterior superior temporal and middle temporal gyrus. In contrast, the integrative-priming effect localized to the left anterior inferior frontal gyrus and left anterior temporal cortices. Furthermore, fiber tractography showed that the integrative-priming regions were connected via uncinate fasciculus fiber bundle forming an integrative circuit, whereas the semantic-priming regions connected to the posterior frontal cortex via separated pathways. The results point to dissociable neural pathways underlying the 2 distinct types of priming, illuminating the neural circuitry organization of semantic representation and integration.

Aberrant functional connectivity of resting state networks associated with trait anxiety

Trait anxiety, a personality dimension, has been characterized by functional consequences such as increased distractibility, attentional bias in favor of threat-related information and hyper-responsive amygdala. However, literature on the association between resting state brain functional connectivity, as studied using resting state functional magnetic resonance imaging (rs-fMRI), and reported anxiety levels in the sub-clinical population is limited. In the present study, we employed rs-fMRI to investigate the possible alterations in the functional integrity of Resting State Networks (RSNs) associated with trait anxiety of the healthy subjects (15 high anxious and 14 low anxious). The rs-fMRI data was analyzed using independent component analysis and a dual regression approach that was applied on 12 RSNs that were identified using FSL. High anxious subjects showed significantly reduced functional connectivity in regions of the default mode network (posterior cingulate gyrus, middle and superior temporal gyrus, planum polare, supramarginal gyrus, temporal pole, angular gyrus and lateral occipital gyrus) which has been suggested to be involved in episodic memory, theory of mind, self-evaluation, and introspection, and perceptual systems including medial visual network, auditory network and another network involving temporal, parieto-occipital and frontal regions. Reduction in resting state connectivity in regions of the perceptual networks might underlie the perceptual, attentional and working memory deficits associated with trait anxiety. To our knowledge, this is the first study to relate trait anxiety to resting state connectivity using independent component analysis.

P12. Neural correlates of apraxia in mild dementia of Alzheimer’s disease – A voxel-based morphometry study

Introduction Apraxia is a neuropsychological syndrome with the hallmark of impaired imitation and/or pantomiming of gestures and postures despite normal motor function and comprehension. Whereas key brain regions for apraxia in patients with left-hemispheric stroke have been suggested, it is unclear whether similar areas contribute to praxis disturbances observed in Alzheimer’s disease (AD). Methods 18 patients with mild AD received high-resolution 3.0 Tesla T1-weighted MRI scans of the brain and were tested for praxis disturbances with the help of a modern apraxia screening test (Cologne Apraxia Screening; CAS) incorporating tasks on limb and face imitation as well as pantomime of object-use. We used a voxel-based morphometry (VBM) analysis to explore associations between gray matter (GM) volume and CAS scores. Results All apraxia scores showed significant associations with GM volume within posterior brain regions. Limb imitation (CAS 2.2) was associated with GM volume in bilateral inferior occipital gyrus, right middle temporal gyrus as well as medial parietal areas, mainly the precuneus. Pantomime of object-use (CAS 1) showed a pattern of right lateralized clusters in posterior middle temporal gyrus, and both inferior and superior parietal areas, again stretching into the precuneus. Imitation of face postures (CAS 2.1) was mainly correlated with GM volume in inferior occipital and left fusiform gyrus. Discussion Limb apraxia in patients after stroke has consistently been associated with lesions in a left lateralized temporo-parieto-frontal brain network with an emphasis on the inferior parietal lobe. Our results from apraxic patients with AD are compatible with the suggested networks, however a more posterior and more bilateral (or even right-lateralized) distribution of associated brain areas emerged, suggesting a stronger influence of visuo-perception on apraxic phenomena in AD. In line with this, both tasks of limb apraxia (imitation and pantomime) showed associations with medial/dorsal areas within the parietal lobe, in particular with the precuneus. The precuneus is a target of early neurodegeneration in AD, shows extensive connections to both, inferior parietal lobe and supplementary motor cortex and is involved in motor imagery processes (i.e., mental visualization of spatially complex motor actions). It may thus constitute a key region for limb apraxia in AD. Face imitation however, was not correlated with parietal GM volume, corroborating previous results of body-part specificity in apraxia.

The effect of synesthetic associations between the visual and auditory modalities on the Colavita effect.

The Colavita effect refers to the phenomenon that when confronted with an audiovisual stimulus, observers report more often to have perceived the visual than the auditory component. The Colavita effect depends on low-level stimulus factors such as spatial and temporal proximity between the unimodal signals. Here, we examined whether the Colavita effect is modulated by synesthetic congruency between visual size and auditory pitch. If the Colavita effect depends on synesthetic congruency, we expect a larger Colavita effect for synesthetically congruent size/pitch (large visual stimulus/low-pitched tone; small visual stimulus/high-pitched tone) than synesthetically incongruent (large visual stimulus/high-pitched tone; small visual stimulus/low-pitched tone) combinations. Participants had to identify stimulus type (visual, auditory or audiovisual). The study replicated the Colavita effect because participants reported more often the visual than auditory component of the audiovisual stimuli. Synesthetic congruency had, however, no effect on the magnitude of the Colavita effect. EEG recordings to congruent and incongruent audiovisual pairings showed a late frontal congruency effect at 400–550 ms and an occipitoparietal effect at 690–800 ms with neural sources in the anterior cingulate and premotor cortex for the 400- to 550-ms window and premotor cortex, inferior parietal lobule and the posterior middle temporal gyrus for the 690- to 800-ms window. The electrophysiological data show that synesthetic congruency was probably detected in a processing stage subsequent to the Colavita effect. We conclude that—in a modality detection task—the Colavita effect can be modulated by low-level structural factors but not by higher-order associations between auditory and visual inputs.

Development of Tool Representations in the Dorsal and Ventral Visual Object Processing Pathways.

Tools represent a special class of objects, because they are processed across both the dorsal and ventral visual object processing pathways. Three core regions are known to be involved in tool processing: the left posterior middle temporal gyrus, the medial fusiform gyrus (bilaterally), and the left inferior parietal lobule. A critical and relatively unexplored issue concerns whether, in development, tool preferences emerge at the same time and to a similar degree across all regions of the tool-processing network. To test this issue, we used functional magnetic resonance imaging to measure the neural amplitude, peak location, and the dispersion of tool-related neural responses in the youngest sample of children tested to date in this domain (ages 4-8 years). We show that children recruit overlapping regions of the adult tool-processing network and also exhibit similar patterns of co-activation across the network to adults. The amplitude and co-activation data show that the core components of the tool-processing network are established by age 4. Our findings on the distributions of peak location and dispersion of activation indicate that the tool network undergoes refinement between ages 4 and 8 years.

Alterations of local spontaneous brain activity and connectivity in adults with high-functioning autism spectrum disorder.

BackgroundPrevious autism research has hypothesized that abnormalities of functional connectivity in autism spectrum disorder (ASD) may vary with the spatial distance between two brain regions. Although several resting-state functional magnetic resonance imaging (rsfMRI) studies have extensively examined long-range (or distant) connectivity in the adult ASD brain, short-range (or local) connectivity has been investigated in less depth. Furthermore, the possible relationship between functional connectivity and brain activity level during the resting state remains unclear.MethodsWe acquired rsfMRI data from 50 adults with high-functioning ASD and 50 matched controls to examine the properties of spontaneous brain activity using measures of local and distant connectivity together with a measure of the amplitude of brain activity, known as fractional amplitude of low-frequency fluctuation (fALFF). The two connectivity measures were calculated using a common graph-theoretic framework. We also examined the spatial overlaps between these measures and possible relationships of these disrupted functional measures with autistic traits assessed by the Autism-Spectrum Quotient (AQ).ResultsCompared to the controls, participants with ASD exhibited local over-connectivity in the right superior frontal gyrus and middle frontal gyrus, accompanied by local under-connectivity in the bilateral fusiform gyri (FG) and right middle temporal gyrus (MTG). On the other hand, we did not find any significant alterations in distant connectivity. Participants with ASD also exhibited reduced fALFF in the right middle occipital gyrus, lingual gyrus, and FG. Further conjunction and spatial overlap analyses confirmed that the spatial pattern of reduced fALFF substantially overlapped with that of local under-connectivity, demonstrating the co-occurrence of disrupted connectivity and spontaneous activity level in the right inferior occipital gyrus, posterior MTG (pMTG), and FG. Finally, within the ASD group, disrupted local connectivity in the right pMTG significantly correlated with the “social interaction” subscale score of the AQ.ConclusionsThese findings revealed local functional disruptions in the occipital and temporal regions, especially the right FG and pMTG, in the form of co-occurrence of spontaneous brain activity level and local connectivity, which may underline social and communicative dysfunctions in adult ASD.Electronic supplementary materialThe online version of this article (doi:10.1186/s13229-015-0026-z) contains supplementary material, which is available to authorized users.

Cerebral activations related to writing and drawing with each hand.

BackgroundWriting is a sequential motor action based on sensorimotor integration in visuospatial and linguistic functional domains. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand. In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing.MethodsSixteen healthy right-handed subjects were scanned during audition-guided writing of short sentences and simple figure drawing without visual feedback. Tapping with a pencil served as a basic control task for the two higher-order motor conditions. Activation differences were assessed with Statistical Parametric Mapping (SPM).ResultsWriting and drawing showed parietal-premotor and posterior inferior temporal activations in both hemispheres when compared to tapping. Drawing activations were rather symmetrical for each hand. Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of particularly the right hemisphere. Writing contrasted to drawing revealed left-sided activations in the dorsal and ventral premotor cortex, Broca’s area, pre-Supplementary Motor Area and posterior middle and inferior temporal gyri, without parietal activation.DiscussionThe audition-driven postero-inferior temporal activations indicated retrieval of virtual visual form characteristics in writing and drawing, with additional activation concerning word form in the left hemisphere. Similar parietal processing in writing and drawing pointed at a common mechanism by which such visually formatted information is used for subsequent sensorimotor integration along a dorsal visuomotor pathway. In this, the left posterior middle temporal gyrus subserves phonological-orthographical conversion, dissociating dorsal parietal-premotor circuitry from perisylvian circuitry including Broca's area.

Developmental changes in the neural influence of sublexical information on semantic processing

Functional magnetic resonance imaging (fMRI) was used to examine the developmental changes in a group of normally developing children (aged 8–12) and adolescents (aged 13–16) during semantic processing. We manipulated association strength (i.e. a global reading unit) and semantic radical (i.e. a local reading unit) to explore the interaction of lexical and sublexical semantic information in making semantic judgments. In the semantic judgment task, two types of stimuli were used: visually-similar (i.e. shared a semantic radical) versus visually-dissimilar (i.e. did not share a semantic radical) character pairs. Participants were asked to indicate if two Chinese characters, arranged according to association strength, were related in meaning. The results showed greater developmental increases in activation in left angular gyrus (BA 39) in the visually-similar compared to the visually-dissimilar pairs for the strong association. There were also greater age-related increases in angular gyrus for the strong compared to weak association in the visually-similar pairs. Both of these results suggest that shared semantics at the sublexical level facilitates the integration of overlapping features at the lexical level in older children. In addition, there was a larger developmental increase in left posterior middle temporal gyrus (BA 21) for the weak compared to strong association in the visually-dissimilar pairs, suggesting conflicting sublexical information placed greater demands on access to lexical representations in the older children. All together, these results suggest that older children are more sensitive to sublexical information when processing lexical representations.

Role of the posterior temporal lobe during language tasks: a virtual lesion study using repetitive transcranial magnetic stimulation.

Functional brain imaging studies have suggested that the superior temporal gyrus (STG) and the middle temporal gyrus (MTG) are involved in phonological and lexical-semantic processing, respectively. However, the precise role of the posterior temporal lobe is not fully understood. To clarify the functional relevance of the left posterior STG and MTG during language processing, we used neuronavigation-guided repetitive transcranial magnetic stimulation (rTMS). The reaction times and error rates for 12 healthy volunteers performing auditory repetition and lexical-semantic decision tasks were compared before and during rTMS stimulation. We applied 1 Hz rTMS over the left posterior STG or MTG or sham stimulation for 10 min in a random order. Stimulation of the left posterior MTG significantly slowed the response time for the lexical-semantic decision task from 478.9±56.5 to 583.1±80.0 ms. However, stimulation over the left posterior STG or MTG did not affect the response time or the error rate for the auditory repetition task. Our results suggest that the left posterior MTG might be involved in lexical decision making. Neuronavigation-guided rTMS virtual lesion studies could help determine the functional roles of specific brain areas in language processing, and our findings provide new evidence supporting the use of neuromodulation through rTMS for patients with aphasia.

PD1-10 SUPRASPINAL CONTROL OF LOWER URINARY TRACT FUNCTION IN PATIENTS WITH SPINAL CORD INJURY: AN FMRI STUDY

INTRODUCTION AND OBJECTIVES: The control of the lower urinary tract (LUT) is a complex, multilevel process involving both the peripheral and central nervous system. Most patients with spinal cord injury (SCI) suffer from neurogenic LUT dysfunction and LUT symptoms severely impair the patients’ health-related quality of life. Although there are several concepts regarding neuronal control and perception in the normal and pathological LUT condition, the exact mechanisms involved remain to be elucidated. METHODS: In this functional magnetic resonance imaging (fMRI) study, we prospectively assessed 20 patients (mean age 43 years old, range 25e75) with cervical and thoracic SCI (12 with complete and 8 with incomplete lesion) suffering from neurogenic detrusor overactivity. All subjects underwent data acquisition in a 3 Tesla scanner. The scan paradigm (SP) comprised 3 different bladder stimulations: (1) repetitive bladder filling of 100mL body warm saline starting with an empty bladder, (2) repetitive infusion and withdrawal (100mL) of body warm saline starting with a pre-filled bladder and (3) repetitive bladder filling of 100mL cold saline. Date was analysed using SPM8. Second-level random effects group analysis (at a voxel-threshold of P<0.001 using false discovery rate correction at cluster level) was performed to account for between subject variability. Only subjects with significant activity (first-level analysis, P1⁄40.05 familywise error rate) were included. RESULTS: 6 subjects had to be excluded from certain analysis due to excessive head motions, autonomic dysreflexia or urinary incontinence during data acquisition. At first-level analysis, we found significant activation in 67% (12/17), 56% (9/15) and 66% (10/15) for SP (1), (2) and (3), respectively. At second-level analysis, significant activation was found in all 3 SP. (1): right inferior frontal gyrus (BA 45), left middle frontal gyrus (BA 10/46), left superior medial frontal gyrus, dorsal posterior cingulate area (BA 31) and bilateral middle temporal gyrus (BA21); (2): anterior left insula and inferior parietal lobe; (3): right precentral gyrus (BA 6) and left superior parietal lobe (BA 7). Activations were seen in both complete and incomplete SCI patients. CONCLUSIONS: In our patients with SCI, significant brain activation similar as reported for healthy subjects, non-neurological and other neurological patients with detrusor overactivity was detected. SP (1) showed activation in more brain areas than (2) and (3). Our findings suggest that extra-spinal sensory pathways might also be involved in LUT control.

The neural basis of perceiving person interactions

This study examined whether the grouping of people into meaningful social scenes (e.g., two people having a chat) impacts the basic perceptual analysis of each partaking individual. To explore this issue, we measured neural activity using functional magnetic resonance imaging (fMRI) while participants sex-categorized congruent as well as incongruent person dyads (i.e., two people interacting in a plausible or implausible manner). Incongruent person dyads elicited enhanced neural processing in several high-level visual areas dedicated to face and body encoding and in the posterior middle temporal gyrus compared to congruent person dyads. Incongruent and congruent person scenes were also successfully differentiated by a linear multivariate pattern classifier in the right fusiform body area and the left extrastriate body area. Finally, increases in the person scenes' meaningfulness as judged by independent observers was accompanied by enhanced activity in the bilateral posterior insula. These findings demonstrate that the processing of person scenes goes beyond a mere stimulus-bound encoding of their partaking agents, suggesting that changes in relations between agents affect their representation in category-selective regions of the visual cortex and beyond.

Early cortical thickness change after mild traumatic brain injury following motor vehicle collision.

In a motor vehicle collision (MVC), survivors often receive mild traumatic brain injuries (mTBI). Although there have been some reports of early white matter changes after an mTBI, much less is known about early cortical structural changes. To investigate early cortical changes within a few days after an MVC, we compared cortical thickness of mTBI survivors with non-mTBI survivors, then reexamined cortical thickness in the same survivors 3 months later. MVC survivors were categorized as mTBI or non-mTBI based on concussive symptoms documented in emergency departments (EDs). Cortical thickness was measured from MRI images using FreeSurfer within a few days and again at 3 months after MVC. Post-traumatic stress symptoms and physical conditions were also assessed. Compared with the non-mTBI group (n = 23), the mTBI group (n = 21) had thicker cortex in the left rostral middle frontal (rMFG) and right precuneus gyri, but thinner cortex in the left posterior middle temporal gyrus at 7.2 ± 3.1 days after MVC. After 3 months, cortical thickness had decreased in left rMFG in the mTBI group but not in the non-mTBI group. The cortical thickness of the right precuneus region in the initial scans was positively correlated with acute traumatic stress symptoms for all survivors and with the number of reduced activity days for mTBI survivors who completed the follow-up. The preliminary results suggest that alterations in cortical thickness may occur at an early stage of mTBI and that frontal cortex structure may change dynamically over the initial 3 months after mTBI.

Combinatorial semantics strengthens angular-anterior temporal coupling

The human semantic combinatorial system allows us to create a wide number of new meanings from a finite number of existing representations. The present study investigates the neural dynamics underlying the semantic processing of different conceptual constructions based on predictions from previous neuroanatomical models of the semantic processing network. In two experiments, participants read sentences for comprehension containing noun-adjective pairs in three different conditions: prototypical (Redundant), nonsense (Anomalous) and low-typical but composable (Contrastive). In Experiment 1 we examined the processing costs associated to reading these sentences and found a processing dissociation between Anomalous and Contrastive word pairs, compared to prototypical (Redundant) stimuli. In Experiment 2, functional connectivity results showed strong co-activation across conditions between inferior frontal gyrus (IFG) and posterior middle temporal gyrus (MTG), as well as between these two regions and middle frontal gyrus (MFG), anterior temporal cortex (ATC) and fusiform gyrus (FG), consistent with previous neuroanatomical models. Importantly, processing of low-typical (but composable) meanings relative to prototypical and anomalous constructions was associated with a stronger positive coupling between ATC and angular gyrus (AG). Our results underscore the critical role of IFG-MTG co-activation during semantic processing and how other relevant nodes within the semantic processing network come into play to handle visual-orthographic information, to maintain multiple lexical-semantic representations in working memory and to combine existing representations while creatively constructing meaning.

A distributed network critical for selecting among tool-directed actions

Tools pose a challenge to the need to select actions appropriate for task goals and environmental constraints. For many tools (e.g., calculator), actions for “using” and “grasping-to-move” conflict with each other and may compete during selection. To date, little is known about the mechanisms that enable selection between possible tool actions or their neural substrates. The study of patients with chronic left hemisphere stroke, many of whom are deficient in tool-use action (apraxic), provides an opportunity to elucidate these issues. Here, 31 such patients pantomimed or recognized tool use actions for “conflict” and “non-conflict” tools. Voxel-based lesion-symptom mapping (VLSM), lesion subtraction, and tractographic overlap analyses were used to determine brain regions necessary for selecting among tool-directed actions. Lesions to posterior middle temporal gyrus (pMTG) and anterior intraparietal sulcus (aIPS) tended to impair production of use actions similarly for both conflict and non-conflict tools. By contrast, lesions to the supramarginal gyrus (SMG), inferior frontal gyrus (IFG)/anterior insula, and superior longitudinal fasciculus (SLF) specifically impaired production of use actions for conflict tools. Patients' errors on conflict tools suggested inappropriate selection of grasping actions and difficulty selecting single actions. Use/grasp conflict had no effect on action recognition. We suggest that the SMG/SLF/IFG pathway implements biased competition between possible tool actions, while aIPS and pMTG compute the structure-based and skilled use actions, respectively, that constitute input to this competitive process. This is the first study to demonstrate a reliable link between a characteristic of single tools (i.e., their association with different use and grasp actions) and action selection difficulties. Additionally, the data allow us to posit an SMG-involved subtype of apraxia characterized by an inability to resolve action competition.

Structural connectivity of left cortical speech regions defined by direct cortical stimulation during awake language mapping

Event Abstract Back to Event Structural connectivity of left cortical speech regions defined by direct cortical stimulation during awake language mapping Christian Kell1*, Pavel Hok2, Silke Fuhrmann1, Ines Kropff3, Marie-Therese Forster3, Christian Senft3 and Volker Seifert3 1 Goethe University, Department of Neurology, Germany 2 Palacky University, Department of Neurology, Czechia 3 Goethe University, Department of Neurosurgery, Germany The location of eloquent cortex is highly variable. Left hemispheric surgery thus requires functional language mapping via intraoperative direct cortical electric stimulation during neuropsychological testing, which provides a detailed functional map of regions that are critically involved in the tested task. Although the patient's brains are abnormal due to mass lesions, these results provide nevertheless insights into general Neurophysiological principles. We previously could not find a clear relationship between individual regions involved in articulation, speech planning and picture naming and individual gyrification. To test whether the lack of clear attributable functional roles of individual gyri was related to different structural connectivity, we obtained pre-operative T1 and DWI datasets (3T, 60 dir) in so far 4 patients and performed probabilistic fiber tracking (FDT in FSL) using 5mm spheres around the functionally positive sites as seeds, yielding posterior probability distribution maps thresholded at the 90th percentile of all non-zero values. Independent of individual function, the triangular inferior frontal gyrus (IFG) projected to more rostral parts of the mesial prefrontal cortex (mPFC) compared to the opercular IFG that projected to the more caudal pre-SMA and lateral articulatory motor cortex (M1). Yet, independently from individual location on a given gyrus, anomia sites projected to the mPFC and locally to the opercular IFG. Speech arrest sites had local projections to frontal operculum, M1 and postcentral gyrus but also long-range connections to the dorsal premotor cortex, pre-SMA and via the arcuate fascicle to the posterior middle temporal gyrus. Even adjacent sites on the same gyrus that differed in function showed dissociable structural connectivity. Our results suggest that structure-function relationships are more evident between function and structural connectivity than between function and gyrification. This implies a developmental dissociation between gyrification and functional specialization. Keywords: direct cortical stimulation, structural connectivity, Language mapping, awake brain tumor surgery, probabilistic fiber tracking Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Language Citation: Kell C, Hok P, Fuhrmann S, Kropff I, Forster M, Senft C and Seifert V (2015). Structural connectivity of left cortical speech regions defined by direct cortical stimulation during awake language mapping. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00213 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Dr. Christian Kell, Goethe University, Department of Neurology, Frankfurt, Germany, c.kell@em.uni-frankfurt.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Christian Kell Pavel Hok Silke Fuhrmann Ines Kropff Marie-Therese Forster Christian Senft Volker Seifert Google Christian Kell Pavel Hok Silke Fuhrmann Ines Kropff Marie-Therese Forster Christian Senft Volker Seifert Google Scholar Christian Kell Pavel Hok Silke Fuhrmann Ines Kropff Marie-Therese Forster Christian Senft Volker Seifert PubMed Christian Kell Pavel Hok Silke Fuhrmann Ines Kropff Marie-Therese Forster Christian Senft Volker Seifert Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.