Visual Naming Research Articles

P10. ‘Clustered sparse’ fMRI using simultaneous multislice excitation in language mapping

The use of functional MRI (fMRI) in language research is impaired by acoustic noise produced by the scanner. To reduce scanner noise during stimulus presentation, ‘sparse’ acquisition schemes have been developed in which volume acquisitions are interleaved with periods of silence. This reduces the number of acquired volumes over time. Thus, statistical power must be weighed against scanner time and the subjects distress. To address the limitations of sparse acquisition protocols, clustered sparse acquisition schemes have emerged. Here, we have established a clustered sparse acquisition protocol using simultaneous multisclice imaging acceleration. MRI data were collected using a Philips Ingenia 3T full body scanner. Functional MRI scanning was performed using a standard (simple sparse sampling) versus a clustered sparse acquisition protocol, where three volumes are acquired every twelve seconds (TR = 1200 ms, TE = 30 ms, Flip Angle = 90°, 36 slices, voxel size = 3 × 3 × 3 mm, multiband factor = 2). In this pilot study, five healthy subjects were investigated by (i) a motor (i.e., repetitive thumb, lips and toe movements triggered by a visual cue) and (ii) a language task (i.e., visual object naming), both presented using Psychopy on a screen inside the scanner room. Functional image analysis was performed using SPM12. The three images acquired in one cluster are subject to differing longitudinal magnetization and therefore differing T2* and T1 effects. To account for this, data were analyzed separately for each time point of acquisition (TPA). The first images from each TPA were realigned to each other, then the remaining images were realigned to the first. Differences in scan intensity were removed by grand mean scaling. A box car function was used. Using clustered sparse acquisition, the number of image volumes acquired per event could be increased by factor 3–5. Preliminary results suggest an accordingly significant increase in statistical power, with stronger activations revealed by the clustered sparse sampling protocol for both fMRI paradigms (motor and language task). Strongest activations (local activation maximum) were observed within the primary motor cortex by motor experiment and in the anterior superior temporal gyrus by visual object naming. Pilot data acquired using both a motor and a visual object naming task and clustered sparse sampling shows promise for the primary study goal of reducing scan time by increasing statistical power. Such advances are particularly important for clinical applications, given the limited alertness and compliance of patients e.g. before brain tumor resection.

Left temporal lobe language network connectivity in temporal lobe epilepsy.

Impairment of naming function is a critical problem for temporal lobe epilepsy patients, yet the neural correlates of the disruption of temporal lobe language networks are poorly understood. Using functional MRI, we investigated the activation and task-related functional connectivity of left temporal lobe language networks and their relation to clinical naming performance and disease characteristics. We studied 59 adult patients with temporal lobe epilepsy (35 left temporal lobe epilepsy) and 32 healthy controls with auditory and visual naming functional MRI tasks. Time series of activation maxima in the left posterior inferior temporal lobe were extracted to create a psychophysiological interaction regressor for subsequent seed-based whole-brain task-related functional connectivity analyses. Correlational analyses were performed to assess the association of functional MRI activation and functional connectivity with clinical naming scores, age of onset of epilepsy, and duration of epilepsy. Auditory naming elicited activation in the left posterior inferior temporal gyrus and visual naming in the left fusiform gyrus across all groups. Activations in the left inferior temporal gyrus, left thalamus and left supplementary motor region during auditory naming as well as left fusiform activations during picture naming correlated with better clinical naming performance. Functional connectivity analyses indicated coupling of left posterior inferior temporal regions to bilateral anterior and posterior temporal lobe regions and the bilateral inferior precentral gyrus as well as contralateral occipital cortex. Stronger functional connectivity was associated with better clinical naming performance in all groups. In patients with left temporal lobe epilepsy only, functional connectivity increased with later age of onset of epilepsy and shorter disease duration. This suggests that onset of seizures early in life and prolonged disease duration lead to disrupted recruitment of temporal lobe networks ipsilateral to the seizure focus, which might account for naming deficits in temporal lobe epilepsy.

A lexical semantic hub for heteromodal naming in middle fusiform gyrus.

Semantic memory underpins our understanding of objects, people, places, and ideas. Anomia, a disruption of semantic memory access, is the most common residual language disturbance and is seen in dementia and following injury to temporal cortex. While such anomia has been well characterized by lesion symptom mapping studies, its pathophysiology is not well understood. We hypothesize that inputs to the semantic memory system engage a specific heteromodal network hub that integrates lexical retrieval with the appropriate semantic content. Such a network hub has been proposed by others, but has thus far eluded precise spatiotemporal delineation. This limitation in our understanding of semantic memory has impeded progress in the treatment of anomia. We evaluated the cortical structure and dynamics of the lexical semantic network in driving speech production in a large cohort of patients with epilepsy using electrocorticography (n = 64), functional MRI (n = 36), and direct cortical stimulation (n = 30) during two generative language processes that rely on semantic knowledge: visual picture naming and auditory naming to definition. Each task also featured a non-semantic control condition: scrambled pictures and reversed speech, respectively. These large-scale data of the left, language-dominant hemisphere uniquely enable convergent, high-resolution analyses of neural mechanisms characterized by rapid, transient dynamics with strong interactions between distributed cortical substrates. We observed three stages of activity during both visual picture naming and auditory naming to definition that were serially organized: sensory processing, lexical semantic processing, and articulation. Critically, the second stage was absent in both the visual and auditory control conditions. Group activity maps from both electrocorticography and functional MRI identified heteromodal responses in middle fusiform gyrus, intraparietal sulcus, and inferior frontal gyrus; furthermore, the spectrotemporal profiles of these three regions revealed coincident activity preceding articulation. Only in the middle fusiform gyrus did direct cortical stimulation disrupt both naming tasks while still preserving the ability to repeat sentences. These convergent data strongly support a model in which a distinct neuroanatomical substrate in middle fusiform gyrus provides access to object semantic information. This under-appreciated locus of semantic processing is at risk in resections for temporal lobe epilepsy as well as in trauma and strokes that affect the inferior temporal cortex-it may explain the range of anomic states seen in these conditions. Further characterization of brain network behaviour engaging this region in both healthy and diseased states will expand our understanding of semantic memory and further development of therapies directed at anomia.

T104. Neural correlates of sign language and spoken language revealed by electrocorticography

Introduction Electrocorticography (ECoG) is a powerful tool to monitor cortical neurophysiology and can be employed to elucidate high order cognitive functions such as language. Clinically, electrical stimulation mapping (ESM) is the gold standard used to identify eloquent cortex which should be spared resection during surgery for patients. We developed a battery of tasks that mirror the ESM paradigm but can functionally track neural activity from stimulus presentation through speech output under multiple cognitive demands. Here we describe the neural propagation maps during both speech and sign language output in a case of a 28 year old male, hearing intact and bilingual in English and American sign language, with pharmaco-resistant epilepsy who was surgically implanted with electrodes for the clinical purpose of identifying his seizure onset zones. Methods The patient was implanted, for the purposes of his clinical care, with an electrode grid over the left temporal parietal occipital cortex, strips over the left frontal, temporal, and occipital regions, and depths within the left parietal lobe. During lulls in clinical treatment, we administered five language tasks involving visual naming, word reading, auditory repetition, auditory naming, and auditory comprehension. We focused our analyses on changes in high gamma activity (70–150 Hz) during the tasks, as high gamma activation has been previously shown to robustly track single trial cortical activity and correlates with neural population firing rates and fMRI BOLD responses. The patient also underwent electrical stimulation mapping using similar language tasks of visual naming, auditory naming, and auditory comprehension, as part of his clinical work up to identify eloquent cortex. Results We identified brain regions with high gamma activation during our language tasks in both spoken English and sign language. In addition we identified discrete regions in the frontal, temporal, parietal, and occipital cortices with sign language specific responses compared to spoken English and provide evidence for temporal propagation of neural activity from post-central to occipital cortices during sign language production. Conclusion We used ECoG high gamma activity to track neural dynamics of language processing in both spoken English and American sign language and to help map language cortex to assist in identifying eloquent regions during electrical brain stimulation.

Intraoperative linguistic performance during awake brain surgery predicts postoperative linguistic deficits

IntroductionAwake craniotomy pursues a balance between extensive tumor resection and preservation of postoperative language function. A dilemma exists in patients whose tumor resection is restricted due to signs of language impairment observed during awake craniotomy. In order to determine the degree to which recovery of language function caused by tumor resection can be achieved by spontaneous neuroplasticity, the change in postoperative language function was compared to quantified intraoperative linguistic performance.MethodsThe modified, short-form Boston Diagnostic Aphasia Examination (sfBDAE) was used to assess pre- and postoperative language functions; visual object naming (DO 80) and semantic-association (Pyramid and Palm Tree Test, PPTT) tests assessed intraoperative linguistic performance. DO 80 and PPTT were performed alternatively during subcortical functional monitoring while performing tumor resection and sfBDAE was assessed 1-week postoperatively.ResultsMost patients with observed language impairment during awake surgery showed improved language function postoperatively. Both intraoperative DO 80 and PPTT showed significant correlation to postoperative sfBDAE domain scores (p < 0.05), with a higher correlation observed with PPTT. A linear regression model showed that only PPTT predicted the postoperative sfBDAE domain scores with the adjusted R2 ranging from 0.51 to 0.89 (all p < 0.01). Receiver operating characteristic analysis showed a cutoff value of PPTT that yielded a sensitivity of 80% and specificity of 100%.ConclusionPPTT may be a feasible tool for intraoperative linguistic evaluation that can predict postoperative language outcomes. Further studies are needed to determine the extent of tumor resection that optimizes the postoperative language following neuroplasticity.

The cognitive functioning of older adult instrumental musicians and non-musicians

ABSTRACTThis study examined similarities and differences in the cognitive profiles of older adult instrumental musicians and non-musicians. We compared neuropsychological test scores among older adult non-musicians, low-activity musicians (<10 years of lessons), and high-activity musicians (≥10 years of lessons), controlling for self-reported physical and social activity, years of education, and overall health. Significant differences among groups were found on tasks of visual spatial ability, naming, and executive functioning. No significant differences were found on tests of attention/processing speed, or episodic memory. The current study supports late life cognitive benefits of early musical training, but only in select cognitive domains, including language, executive functioning, and visual spatial ability. The results are discussed in the context of cognitive reserve and aging.

Visual attention and object naming in humanoid robots using a bio-inspired spiking neural network

Recent advances in behavioural and computational neuroscience, cognitive robotics, and in the hardware implementation of large-scale neural networks, provide the opportunity for an accelerated understanding of brain functions and for the design of interactive robotic systems based on brain-inspired control systems. This is especially the case in the domain of action and language learning, given the significant scientific and technological developments in this field. In this work we describe how a neuroanatomically grounded spiking neural network for visual attention has been extended with a word learning capability and integrated with the iCub humanoid robot to demonstrate attention-led object naming. Experiments were carried out with both a simulated and a real iCub robot platform with successful results. The iCub robot is capable of associating a label to an object with a ‘preferred’ orientation when visual and word stimuli are presented concurrently in the scene, as well as attending to said object, thus naming it. After learning is complete, the name of the object can be recalled successfully when only the visual input is present, even when the object has been moved from its original position or when other objects are present as distractors.

Electrocorticographic high-gamma modulation with passive listening paradigm for pediatric extraoperative language mapping.

This prospective study compared the topography of high-gamma modulation (HGM) during a story-listening task requiring negligible patient cooperation, with the conventional electrical stimulation mapping (ESM) using a picture-naming task, for presurgical language localization in pediatric drug-resistant epilepsy. Patients undergoing extraoperative monitoring with subdural electrodes were included. Electrocorticographic signals were recorded during quiet baseline and a story-listening task. The likelihood of 70- to 150-Hz power modulation during the listening task relative to the baseline was estimated for each electrode and plotted on a cortical surface model. Sensitivity, specificity, accuracy, and diagnostic odds ratio (DOR) were estimated compared to ESM, using a meta-analytic framework. Nineteen patients (10 with left hemisphere electrodes) aged 4-19 years were analyzed. HGM during story listening was observed in bilateral posterior superior temporal, angular, supramarginal, and inferior frontal gyri, along with anatomically defined language association areas. Compared to either cognitive or both cognitive and orofacial sensorimotor interference with naming during ESM, left hemisphere HGM showed high specificity (0.82-0.84), good accuracy (0.66-0.70), and DOR of 2.23 and 3.24, respectively. HGM was a better classifier of ESM language sites in the left temporoparietal cortex compared to the frontal lobe. Incorporating visual naming with the story-listening task substantially improved the accuracy (0.80) and DOR (13.61) of HGM mapping, while the high specificity (0.85) was retained. In the right hemisphere, no ESM sites for aphasia were seen, and the results of HGM and ESM comparisons were not significant. HGM associated with story listening is a specific determinant of left hemisphere ESM language sites. It can be used for presurgical language mapping in children who cannot cooperate with conventional language tasks requiring active engagement. Incorporation of additional language tasks, if feasible, can further improve the diagnostic accuracy of language localization with HGM.

Neuropsychological performance in patients with asymptomatic HIV-1 infection

ABSTRACTHuman immunodeficiency virus (HIV-1) infection and acquired immunodeficiency syndrome (AIDS) lead to neurocognitive disorders; however, there is still much knowledge to be gained regarding HIV-associated neurocognitive disorders. The purpose of this study was to assess the cognitive performance, instrumental activities of daily living, depression, and anxiety in patients with asymptomatic HIV-1 infections compared with seronegative participants without neurocognitive impairment. We studied a sample consisted of 60 patients with asymptomatic HIV-1 infections and 60 seronegative participants without neurocognitive impairment from the city of Barranquilla, Colombia, with a mean age of 36.07 years. A protocol of neuropsychological and psychopathological tests was applied to the participants. The group of patients with asymptomatic HIV infections significantly underperformed on tasks that assessed global cognitive screening, attention span, learning, phonemic verbal fluency, auditory-verbal comprehension, information processing speed, cognitive flexibility, and motor skills compared to the group of seronegative participants. No significant differences were found in memory, visual confrontation naming, vocabulary, inhibition, and instrumental activities of daily living. Additionally, the patients with asymptomatic HIV-1 infection had a higher anxiety index than the seronegative participants, but no significant difference was found in depression. A correlation was found between depression and anxiety. In conclusion, the patients with asymptomatic HIV-1 infection had lower cognitive performances than the seronegative participants in the cognitive functions mentioned above and more anxiety but still performed the instrumental activities of daily living.

A database of orthography-semantics consistency (OSC) estimates for 15,017 English words.

Orthography-semantics consistency (OSC) is a measure that quantifies the degree of semantic relatedness between a word and its orthographic relatives. OSC is computed as the frequency-weighted average semantic similarity between the meaning of a given word and the meanings of all the words containing that very same orthographic string, as captured by distributional semantic models. We present a resource including optimized estimates of OSC for 15,017 English words. In a series of analyses, we provide a progressive optimization of the OSC variable. We show that computing OSC from word-embeddings models (in place of traditional count models), limiting preprocessing of the corpus used for inducing semantic vectors (in particular, avoiding part-of-speech tagging and lemmatization), and relying on a wider pool of orthographic relatives provide better performance for the measure in a lexical-processing task. We further show that OSC is an important and significant predictor of reaction times in visual word recognition and word naming, one that correlates only weakly with other psycholinguistic variables (e.g., family size, word frequency), indicating that it captures a novel source of variance in lexical access. Finally, some theoretical and methodological implications are discussed of adopting OSC as one of the predictors of reaction times in studies of visual word recognition.

Auditory and visual naming tests for children

ABSTRACTAssessment of naming in children has been hampered by the use of tests that were developed, either to assess naming in adults or to assess related verbal functions in children. We developed comparable visual naming test (VNT) and auditory description naming (ANT) specifically for children. We collected normative data, not only for accuracy, typically the sole performance measure, but also for response time (RT) and reliance on phonemic cuing. The normative sample consisted of 200 typically developing children, ages 6–15, with 40 children per 2-year age group (6–7, 8–9, 10–11, 12–13, and 14–15). Children were tested individually by a trained examiner. Based on item analysis, naming tests were finalized at 36 items for ages 8–15 and 28 items for ages 6–7. Age-stratified normative data are provided for accuracy, mean RT, tip-of-the-tongues (i.e., delayed but accurate responses plus items named following phonemic cueing), and a summary score, which incorporates all performance measures. Internal and test–retest reliability coefficients for both tests were reasonable. Accuracy scores were high across age groups, indicating that item names were within the mental lexicon of most typically developing children. By contrast, time and cue-based scores improved with age, reflecting greater efficiency in word retrieval with development. These complementary auditory naming and visual naming tests for children address a longstanding clinical need, improving upon the current standard with respect to the sensitivity of performance measures and the addition of an auditory verbal component to the assessment of naming in children.

PO173 Reorganisation of language following temporal lobe epilepsy surgery

Background Temporal lobe epilepsy (TLE) is the most common cause of refractory focal epilepsy and anterior temporal lobe resection (ATLR) offers seizure freedom for up to 80%. ATLR however, is associated with a risk of memory and language decline, particularly naming. Functional magnetic resonance imaging (fMRI) can be used to examine the functional anatomy of language and memory, and to predict the risks of cognitive decline following surgery. Some reorganisation of language networks has been demonstrated in individuals with TLE. However, most studies use language tasks that predominantly activate the frontal lobe. Aims An auditory and visual naming language fMRI paradigm has been developed that activates temporal lobe language areas. The current need is to employ this paradigm prospectively to assess the reorganisation of language networks in individual patients. Methods Language ability will be assessed in individuals with TLE prior to left and right ATLR, using McKenna Graded Naming Test. Language fMRI paradigms will be carried out on a 3 T GE MRI scanner. The reorganisation of language networks before and after ATLR will be assessed to determine the extent to which language reorganisation occurs and whether it is effective.

Examination of the Construct Validity of the Repeatable Battery for the Assessment of Neuropsychological Status Language Index in a Mixed Neurological Sample.

We sought to examine the construct validity of the Language Index of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Archival neuropsychological data were collected for 2,057 individuals of diverse neurological etiologies. Correlations were seen between the RBANS Language Index and its indices (Semantic Fluency r = .727; Picture Naming r = .786), between Semantic Fluency and both Category Fluency (r = .379) and the Controlled Oral Word Association test (r = .375), and between Picture Naming and both Visual Naming from the Multilingual Aphasia Examination (r = .447) and the Boston Naming Test (r = .519). Finally, Picture Naming predicted performance on both Visual Naming [F(1,495) = 123.36, p < .000] and the Boston Naming Test [F(1,262) = 96.28, p < .000]. Given these results, support for the interpretation of RBANS Language Index appears warranted in a diverse clinical sample.

Intracerebral stimulation of left and right ventral temporal cortex during object naming

While object naming is traditionally considered asa left hemisphere function, neuroimaging studies have reported activations related to naming in the ventral temporal cortex (VTC) bilaterally. Our aim was to use intracerebral electrical stimulation to specifically compare left and right VTC in naming. In twenty-three epileptic patients tested for visual object naming during stimulation, the proportion of naming impairments was significantly higher in the left than in the right VTC (31.3% vs 13.6%). The highest proportions of positive naming sites were found in the left fusiform gyrus and occipito-temporal sulcus (47.5% and 31.8%). For 17 positive left naming sites, an additional semantic picture matching was carried out, always successfully performed. Our results showed the enhanced role of the left compared to the right VTC in naming and suggest that it may be involved in lexical retrieval rather than in semantic processing.

Assessing the Role of the Hippocampus in Visual Naming Using Hippocampal Morphometry in Left Temporal Lobe Epilepsy (P4.243)

Assessing the Role of the Hippocampus in Visual Naming Using Hippocampal Morphometry in Left Temporal Lobe Epilepsy (P4.243)

Recovery of orthographic processing after stroke: A longitudinal fMRI study

An intact orthographic processing system is critical for normal reading and spelling. Here we investigate the neural changes associated with impairment and subsequent recovery of the orthographic lexical processing system in an individual with an ischemic left posterior cerebral artery (PCA) stroke. This work describes a longitudinal case study of a patient, whose initials are MMY, with impairments in orthographic lexical processing for reading and spelling at stroke onset, and who recovered these skills within 1 year post stroke. We tested the hypothesis that this acute impairment to reading and spelling would be associated with a selective loss of neural activation in the left fusiform gyrus (FG), and that subsequent recovery would be associated with a gain of neural activation in this region. MMY's case provided a unique opportunity to assess the selectivity of neural changes because she demonstrated a behavioral recovery of naming as well; i.e., if there is neural recovery for reading and spelling, but not naming, then these neural changes are selective to the recovery of orthographic processing. To test our hypothesis, we examined longitudinal behavioral and functional magnetic resonance imaging (fMRI) data of reading, spelling, and visual object naming acquired acutely, 3 weeks, 5 months, and one year post stroke. In confirmation of our hypothesis, the loss and subsequent gain of orthographic lexical processing was associated with up-regulation of neural activation in areas previously associated with orthographic lexical processing: i.e., the left mid-FG and inferior frontal junction (IFJ). Furthermore, these neural changes were found to be selective to orthographic processing, as they were observed for reading and spelling, but not for visual object naming within the left mid-FG. This work shows that left PCA stroke can temporarily and selectively disrupt the orthographic lexical processing system, not only in the posterior region adjacent to the stroke, but also in relatively distant frontal orthographic processing regions.

Presurgical language localization with visual naming associated ECoG high- gamma modulation in pediatric drug-resistant epilepsy.

This prospective study compared presurgical language localization with visual naming-associated high-γ modulation (HGM) and conventional electrical cortical stimulation (ECS) in children with intracranial electrodes. Patients with drug-resistant epilepsy who were undergoing intracranial monitoring were included if able to name pictures. Electrocorticography (ECoG) signals were recorded during picture naming (overt and covert) and quiet baseline. For each electrode the likelihood of high-γ (70-116Hz) power modulation during naming task relative to the baseline was estimated. Electrodes with significant HGM were plotted on a three-dimensional (3D) cortical surface model. Sensitivity, specificity, and accuracy were calculated compared to clinical ECS. Seventeen patients with mean age of 11.3years (range 4-19) were included. In patients with left hemisphere electrodes (n=10), HGM during overt naming showed high specificity (0.81, 95% confidence interval [CI] 0.78-0.85), and accuracy (0.71, 95% CI 0.66-0.75, p<0.001), but modest sensitivity (0.47) when ECS interference with naming (aphasia or paraphasic errors) and/or oral motor function was regarded as the gold standard. Similar results were reproduced by comparing covert naming-associated HGM with ECS naming sites. With right hemisphere electrodes (n=7), no ECS-naming deficits were seen without interference with oral-motor function. HGM mapping showed a high specificity (0.81, 95% CI 0.78-0.84), and accuracy (0.76, 95% CI 0.71-0.81, p=0.006), but modest sensitivity (0.44) compared to ECS interference with oral-motor function. Naming-associated ECoG HGM was consistently observed over Broca's area (left posterior inferior-frontal gyrus), bilateral oral/facial motor cortex, and sometimes over the temporal pole. This study supports the use of ECoG HGM mapping in children in whom adverse events preclude ECS, or as a screening method to prioritize electrodes for ECS testing.

Improving language mapping in clinical fMRI through assessment of grammar.

IntroductionBrain surgery in the language dominant hemisphere remains challenging due to unintended post-surgical language deficits, despite using pre-surgical functional magnetic resonance (fMRI) and intraoperative cortical stimulation. Moreover, patients are often recommended not to undergo surgery if the accompanying risk to language appears to be too high. While standard fMRI language mapping protocols may have relatively good predictive value at the group level, they remain sub-optimal on an individual level. The standard tests used typically assess lexico-semantic aspects of language, and they do not accurately reflect the complexity of language either in comprehension or production at the sentence level. Among patients who had left hemisphere language dominance we assessed which tests are best at activating language areas in the brain.MethodWe compared grammar tests (items testing word order in actives and passives, wh-subject and object questions, relativized subject and object clauses and past tense marking) with standard tests (object naming, auditory and visual responsive naming), using pre-operative fMRI. Twenty-five surgical candidates (13 females) participated in this study. Sixteen patients presented with a brain tumor, and nine with epilepsy. All participants underwent two pre-operative fMRI protocols: one including CYCLE-N grammar tests (items testing word order in actives and passives, wh-subject and object questions, relativized subject and object clauses and past tense marking); and a second one with standard fMRI tests (object naming, auditory and visual responsive naming). fMRI activations during performance in both protocols were compared at the group level, as well as in individual candidates.ResultsThe grammar tests generated more volume of activation in the left hemisphere (left/right angular gyrus, right anterior/posterior superior temporal gyrus) and identified additional language regions not shown by the standard tests (e.g., left anterior/posterior supramarginal gyrus). The standard tests produced more activation in left BA 47. Ten participants had more robust activations in the left hemisphere in the grammar tests and two in the standard tests. The grammar tests also elicited substantial activations in the right hemisphere and thus turned out to be superior at identifying both right and left hemisphere contribution to language processing.ConclusionThe grammar tests may be an important addition to the standard pre-operative fMRI testing.

Normal and abnormal category-effects in visual object recognition: A legacy of Glyn W. Humphreys

ABSTRACTAre all categories of objects recognized in the same manner visually? Evidence from neuropsychology suggests they are not, as some brain injured patients are more impaired in recognizing natural objects than artefacts while others show the opposite impairment. In an attempt to explain category-specific deficits for natural objects Glyn Humphreys and colleagues suggested that natural objects are harder to perceptually differentiate than artefacts because natural objects are more structurally similar than artefacts. This explanation was proposed in the context of the Cascade model of visual object naming. While this model has been successful in accounting for a number of observations concerning category-specificity in both patients with brain injury and normal subjects, it has also become clear that there are many important aspects of category-specificity that the model cannot accommodate. These limitations have led to the development of a new model of category-effects at pre-semantic stages in visual object processing, which can be considered a further development of the Cascade model: the Pre-semantic Account of Category-Effects (PACE). Here I give a slightly historical, but primarily integrative, account of this development including recent studies which address important aspects of both the Cascade and the PACE models.

Acoustic correlates of vocal alignment to accented speech

Language users can vocally align to the speech characteristics of other talkers both within and across accent groups. Although perceptual assessments of vocal alignment indicate convergence to accented speech, the acoustic properties of the speech signal that contribute to these perceptual judgments are less clear. The present investigation examined the acoustic correlates of vocal alignment to foreign-accented and native speech and related acoustic to perceptual measures of convergence. Native speakers of American English shadowed utterances produced by four model talkers; male and female native speakers of English and Spanish. Baseline utterances were obtained from visual naming blocks and shadowed utterances were compared to both baseline and model talker utterances. Fundamental frequency (F0), utterance duration, and vowel spectra (F1, F2) served as acoustic indices of vocal alignment. The results showed that different patterns of alignment emerged across the three measures. Utterance duration, but not fundamental frequency or vowel spectra, demonstrated convergence. However, both duration and vowel spectra measures significantly predicted perceptual assessments of vocal alignment. The results suggest that perceptual judgments of alignment behavior depend on multiple acoustic properties and that the dimensions of acoustic change during vocal alignment appear similar across accented and native speech.