Lexico-semantic Impairment in a Case of HSVE to the Left Anterior Temporal Lobe

This study investigates the role of the left anterior temporal lobe (aTL) in semantics. Clinical and neuroscientific investigations propose the aTL bilaterally (BaTL), are implicated in semantics, based on findings that: (1) disruption to BaTL results in a multimodal semantic impairment, observed in semantic dementia (SD) and herpes-simplex-viral-encephalitis (HSVE); (2) impairment can be mimicked by inducing a “virtual lesion” (repetitive-transcranial-magnetic-stimulation) to BaTL in neurologically intact participants; (3) neuroimaging studies identify BaTL activation for semantic tasks (Fig 1, Lambon Ralph et al., 2012, for points 1-3). Anchored in this evidence is the assumption that semantic impairment will result from BaTL damage only. Recently, investigators have suggested a loss of semantic knowledge can result from LaTL damage. Using sensitive tests, this can be observed in chronic stroke (Schwartz et al., 2009) and temporal lobe resection for epilepsy patients (rTLE: Antonucci et al., 2008; Lambon Ralph et al., 2012). Of interest is the striking similarity of rTLE and very early stages of SD (when atrophy is left sided and overlaps with resection) – impairment is mild and the primary symptom is anomia and/or forgetfulness. This builds upon the possibility that a semantic weakness may result from a LaTL lesion. Whilst rTLE studies have provided insight into this notion, one must be cautious – pre-surgical seizures may initiate changes in brain organisation/normal development, and reorganisation of function could occur post-surgery. Chronic stroke studies are problematic since lesions are large and encompass other areas that may contribute to the impairment. Consequently, whether LaTL lesions results in semantic impairment is not entirely understood. The goal of the present case study was to initiate an investigation to determine whether semantic impairment is in fact present following LaTL lesion

A web-based resource for the assessment of language skills in English and Welsh-speaking adults with neurological deficits

We will present a new web-based resource for the assessment of language disorders in English monolinguals and Welsh/English bilingual adults with neurological deficits. Although both languages are typically affected in bilinguals, few valid tools are available to accurately and comprehensively assess both languages, and none in Welsh-English speakers. This impedes both accurate diagnosis and therapeutic efforts. The goal of this work was to provide a secure user-friendly platform to allow clinicians to administer and score tests on-line or offline. The battery includes 16 different tests developed to measure the same abilities in Welsh and in English and to be of comparable difficulty in the two languages. These tests assess a range of language skills: spoken word production (picture naming, naming to definition, translation, repetition), reading (reading aloud, lexical decision, paragraph reading) and written production (spelling to dictation, delayed copy, written picture description). The tests manipulate and/or control for key psycholinguistic variables (e.g., word frequency, length, concreteness, Welsh-English similarity, grammatical class, lexicality). In the on-line version, all tests are programmed to allow automatic and standardized presentation of auditory or visual stimuli. The program also records oral or written responses and response times for each stimulus, and provide summary scores broken down by stimulus category. Each test package includes: a) an introductory section explaining the test aims and rationale, b) instructions on how to administer the test, c) scoring instructions and scoring sheets and d) performance indicators (e.g., Z-score) based on control data from 120 neurologically healthy participants (40 English monolinguals and 80 Welsh-English bilinguals, broken down by age, language and educational level. The presentation will include demos of the interface and of computerized test administration and scoring. Note that this new resource is suitable for the assessment of both English monolingual and Welsh-English bilingual adults.ESRC/MRC; Bangor ESRC Impact Acceleration Accoun

Is translation semantically mediated? Evidence from Welsh-English bilingual aphasia

The involvement of the semantic system in picture naming is undisputed. However, it has been proposed that translation could take place via direct lexical links between L1 and L2 word forms in addition to or instead of via semantics(i.e., with translation going from a spoken word in L1 accessing its meaning and this meaning then leading to the retrieval of the translation equivalent in L2). There is conflicting evidence in the psycholinguistic literature as to the extent of semantic mediation in translation vs. picture naming tasks (Potter et al, 1984; Kroll and Stewart, 1994). More recently, Hernandez et al (2010) investigated this question in a case study of JFF, a proficient bilingual Spanish-Catalan speaker with Alzheimer’s disease and naming difficulties due to a semantic deficit. As JFF’s semantic deficit did not only affect picture naming but also translation tasks, the authors concluded against the existence of functional direct lexical links to support translation. The goal of our study was to explore this issue further in a larger sample of proficient bilingual patients with aphasia and word finding difficulties in both languages. More specifically, we compare the rate of semantic errors produced in naming vs. translation tasks

Impaired integration of object knowledge and visual input in a case of ventral simultanagnosia with bilateral damage to area V4

In this study we report some of the first evidence showing how brain-damage can affect the underlying processes that support the integration of sensory input and prior knowledge during the visual perception of shape. We report the case of patient MT with an acquired ventral simultanagnosia following posterior occipito-temporal lesions encompassing V4 bilaterally. Despite showing normal object recognition for single items, and intact low-level vision, MT was impaired in object identification with overlapping figures displays.Task performance was modulated by familiarity: unlike controls, MT was faster with overlapping displays of abstract shapes than common objects. His performance with overlapping common object displays was also influenced by both the semantic relatedness and visual similarity of the display items. These findings challenge claims that visual perception is driven solely by feedforward mechanisms, and show how brain-damage can selectively impair high-level perceptual processes supporting the integration of stored knowledge and visual sensory input

Costs and benefits of orthographic inconsistency in reading:evidence from a cross-linguistic comparison

We compared reading acquisition in English and Italian children up to late primary school analyzing RTs and errors as a function of various psycholinguistic variables and changes due to experience. Our results show that reading becomes progressively more reliant on larger processing units with age, but that this is modulated by consistency of the language. In English, an inconsistent orthography, reliance on larger units occurs earlier on and it is demonstrated by faster RTs, a stronger effect of lexical variables and lack of length effect (by fifth grade). However, not all English children are able to master this mode of processing yielding larger inter-individual variability. In Italian, a consistent orthography, reliance on larger units occurs later and it is less pronounced. This is demonstrated by larger length effects which remain significant even in older children and by larger effects of a global factor (related to speed of orthographic decoding) explaining changes of performance across ages. Our results show the importance of considering not only overall performance, but inter-individual variability and variability between conditions when interpreting cross-linguistic differences

The size and distribution of midbrain dopaminergic populations are permanently altered by perinatal glucocorticoid exposure in a sex- region- and time-specific manner

Central dopaminergic (DA) systems appear to be particularly vulnerable to disruption by exposure to stressors in early life, but the underlying mechanisms are poorly understood. As endogenous glucocorticoids (GCs) are implicated in other aspects of neurobiological programming, this study aimed to characterize the effects of perinatal GC exposure on the cytoarchitecture of DA populations in the substantia nigra pars compacta (SNc) and the ventral tegmental area (VTA). Dexamethasone was administered non-invasively to rat pups via the mothers' drinking water during embryonic days 16-19 or postnatal days 1-7, with a total oral intake circa 0.075 or 0.15 mg/kg/day, respectively; controls received normal drinking water. Analysis of tyrosine hydroxylase-immunoreactive cell counts and regional volumes in adult offspring identified notable sex differences in the shape and volume of the SNc and VTA, as well as the topographical organization and size of the DA populations. Perinatal GC treatments increased the DA population size and altered the shape of the SNc and VTA as well as the organization of the DA neurons by expanding and/or shifting them in a caudal direction. This response was sexually dimorphic and included a feminization or demasculinization of the three-dimensional cytoarchitecture in males, and subtle differences that were dependent on the window of exposure. These findings demonstrate that inappropriate perinatal exposure to GCs have enduring effects on the organization of midbrain DA systems that are critically important for normal brain function throughout life