Proper name anomia after right-hemispheric lesion: a case study.

This study describes the case of CH, a 68-year-old left-handed woman who suffered a right temporo-parieto-occipital infarct in the territory of the middle cerebral artery and who exhibits severe proper name anomia. During the acute stage, CH was diagnosed with severe amnestic aphasia (Aachen Aphasia Test). Her lesion mirrors those of left hemisphere impairing the processing proper names, without an aphasic language disorder in general. Seven weeks later, language improved to a mild amnestic aphasia that currently does not interfere with her daily life. However, the use of proper names in both the visual and auditory modalities was still impaired and showed no improvement after 6 months of speech therapy. While not being able to name family members or familiar persons, she was, however, still able to describe the persons' backgrounds along with some additional semantic information. Furthermore, in a simple semantic design test, CH was selectively impaired in correctly classifying proper names into their respective word classes. Conversely, she was able to correctly name and classify other word categories (e.g., common nouns). In the subsequent study, we assessed the modalities "auditory comprehension," "picture naming," and "reading comprehension" and classified her responses in the categories "correctly named," "correctly classified," "correctly described attributes" (e.g., occupation) and "falsely named." The results were compared with those of an age-matched healthy control group. In the visual task, CH correctly named 80% of the visualized objects, 3% of the familiar persons and 15% of the familiar city views.

Proper name anomia in poststroke aphasics: evidence from a multiple-case study.

We aimed to characterize difficulties in famous face naming in three poststroke aphasic patients with a lesion limited to the left mid-posterior temporal language regions, sparing the anterior temporal lobe. The patients did not present semantic deficits specific to known people. Nonetheless, they showed difficulties naming famous buildings in addition to famous faces, but they were comparable to healthy controls in generating proper names. Our results support the critical role of the mid-posterior temporal language regions in the lexical retrieval of proper names, namely from pictorial stimuli, in absence of semantic impairments.

The involvement of the thalamus in semantic retrieval: a clinical group study.

There is increasing attention about the role of the thalamus in high cognitive functions, including memory. Although the bulk of the evidence refers to episodic memory, it was recently proposed that the mediodorsal (MD) and the centromedian-parafascicular (CM-Pf) nuclei of the thalamus may process general operations supporting memory performance, not only episodic memory. This perspective agrees with other recent fMRI findings on semantic retrieval in healthy participants. It can therefore be hypothesized that lesions to the MD and the CM-Pf impair semantic retrieval. In this study, 10 patients with focal ischemic lesions in the medial thalamus and 10 healthy controls matched for age, education, and verbal IQ performed a verbal semantic retrieval task. Patients were assigned to a target clinical group and a control clinical group based on lesion localization. Patients did not suffer from aphasia and performed in the range of controls in a categorization and a semantic association task. However, target patients performed poorer than healthy controls on semantic retrieval. The deficit was not because of higher distractibility but of an increased rate of false recall and, in some patients, of a considerably increased rate of misses. The latter deficit yielded a striking difference between the target and the control clinical groups and is consistent with anomia. Follow-up high-resolution structural scanning session in a subsample of patients revealed that lesions in the CM-Pf and MD were primarily associated with semantic retrieval deficits. We conclude that integrity of the MD and the CM-Pf is required for semantic retrieval, possibly because of their role in the activation of phonological representations.

Voice-specific proper name anomia ('phonoanomia') after bilateral temporal hemorrhagic brain lesions.

We describe a patient who developed bilateral temporal lesions due to a haemorrhagic stroke. One year after onset, he showed marked apperceptive prosopagnosia and could not name people from their voices, although he had spared semantic knowledge about people he could not name and could access this knowledge from people's voice. Importantly, the patient was able to retrieve proper name of persons after their description and was able to name sounds and songs; he could also retrieve proper names of monuments, towns and cartoon characters upon visual presentation. No further relevant cognitive impairment was present. This clinical picture represents the auditory counterpart of prosopanomia and could be defined 'phonoanomia'. This case report suggests that naming people from their voice implies specific retrieval processes, and pose specific constraints to theoretical models of person recognition.

White matter microstructural integrity pre- and post-treatment in individuals with chronic post-stroke aphasia.

While previous studies have found that white matter damage relates to impairment severity in individuals with aphasia, further study is required to understand the relationship between white matter integrity and treatment response. In this study, 34 individuals with chronic post-stroke aphasia underwent behavioral testing and structural magnetic resonance imaging at two timepoints. Thirty participants within this sample completed typicality-based semantic feature treatment for anomia. Tractography of bi-hemispheric white matter tracts was completed via Automated Fiber Quantification. Associations between microstructural integrity metrics and behavioral measures were evaluated at the tract level and in nodes along the tract. Diffusion measures of the left inferior longitudinal, superior longitudinal, and arcuate fasciculi were related to aphasia severity and diffusion measures of the left inferior longitudinal fasciculus were related to naming and treatment response. This study also found preliminary evidence of left inferior longitudinal fasciculus microstructural changes following treatment.

Preservation and modulation of specific left hemisphere regions is vital for treated recovery from anomia in stroke.

The location and extent of brain changes that support recovery in chronic stroke is probably related to the structural integrity of the remaining cortex. However, little is known about the specifics of this relationship and how it influences treatment outcome in chronic stroke. To examine this issue, the current study examined frank brain damage and changes in cortical activation as predictors of language-treatment outcome in patients with chronic aphasia caused by stroke. Twenty-six patients received multiple MRI sessions before and after 30 h of aphasia treatment targeting anomia, an impairment in the ability to name common objects. Improved naming was associated with increased brain activation in the anterior and posterior regions of the left hemisphere, whereas damage to the posterior portion of the left middle temporal lobe and the temporal-occipital junction had a particularly negative effect on treatment outcome. Specifically, patients whose brain damage included regions commonly associated with lexical retrieval and phonological processing (e.g., Brodmann's areas 37 and 39) were less likely to show treatment-related improvement in correct naming compared with cases where the same areas were intact. These findings suggest that brain changes associated with improved naming ability in chronic aphasia rely on preservation and recruitment of eloquent cortex in the left hemisphere. In general, it seems likely that a similar relationship between cortical preservation and recruitment may also pertain to recovery from other functional impairments in chronic stroke.

Activity in preserved left hemisphere regions predicts anomia severity in aphasia.

Understanding the neural mechanism that supports preserved language processing in aphasia has implications for both basic and applied science. This study examined brain activation associated with correct picture naming in 15 patients with aphasia. We contrasted each patient's activation to the activation observed in a neurologically healthy control group, allowing us to identify regions with unusual activity patterns. The results revealed that increased activation in preserved left hemisphere areas is associated with better naming performance in aphasia. This relationship was linear in nature; progressively less cortical activation was associated with greater severity of anomia. These findings are consistent with others who suggests that residual language function following stroke relies on preserved cortical areas in the left hemisphere.

Density pervades: an analysis of phonological neighbourhood density effects in aphasic speakers with different types of naming impairment.

We investigated the influence of phonological neighbourhood density (PND) on the performance of aphasic speakers whose naming impairments differentially implicate phonological or semantic stages of lexical access. A word comes from a dense phonological neighbourhood if many words sound like it. Limited evidence suggests that higher density facilitates naming in aphasic speakers, as it does in healthy speakers. Using well-controlled stimuli, Experiment 1 confirmed the influence of PND on accuracy and phonological error rates in two aphasic speakers with phonological processing deficits. In Experiments 2 and 3, we extended the investigation to an aphasic speaker who is prone to semantic errors, indicating a semantic deficit and/or a deficit in the mapping from semantics to words. This individual had higher accuracy, and fewer semantic errors, in naming targets from high- than from low-density neighbourhoods. It is argued that the Results provide strong support for interactive approaches to lexical access, where reverberatory feedback between word- and phoneme-level lexical representations not only facilitates phonological level processes but also privileges the selection of a target word over its semantic competitors.

Neurology of anomia in the semantic variant of primary progressive aphasia.

The semantic variant of primary progressive aphasia (PPA) is characterized by the combination of word comprehension deficits, fluent aphasia and a particularly severe anomia. In this study, two novel tasks were used to explore the factors contributing to the anomia. The single most common factor was a blurring of distinctions among members of a semantic category, leading to errors of overgeneralization in word-object matching tasks as well as in word definitions and object descriptions. This factor was more pronounced for natural kinds than artifacts. In patients with the more severe anomias, conceptual maps were more extensively disrupted so that inter-category distinctions were as impaired as intra-category distinctions. Many objects that could not be named aloud could be matched to the correct word in patients with mild but not severe anomia, reflecting a gradual intensification of the semantic factor as the naming disorder becomes more severe. Accurate object descriptions were more frequent than accurate word definitions and all patients experienced prominent word comprehension deficits that interfered with everyday activities but no consequential impairment of object usage or face recognition. Magnetic resonance imaging revealed three characteristics: greater atrophy of the left hemisphere; atrophy of anterior components of the perisylvian language network in the superior and middle temporal gyri; and atrophy of anterior components of the face and object recognition network in the inferior and medial temporal lobes. The left sided asymmetry and perisylvian extension of the atrophy explains the more profound impairment of word than object usage and provides the anatomical basis for distinguishing the semantic variant of primary progressive aphasia from the partially overlapping group of patients that fulfil the widely accepted diagnostic criteria for semantic dementia.

Brain regions underlying word finding difficulties in temporal lobe epilepsy.

Word finding difficulties are often reported by epileptic patients with seizures originating from the language dominant cerebral hemisphere, for example, in temporal lobe epilepsy. Evidence regarding the brain regions underlying this deficit comes from studies of peri-operative electro-cortical stimulation, as well as post-surgical performance. This evidence has highlighted a role for the anterior part of the dominant temporal lobe in oral word production. These conclusions contrast with findings from activation studies involving healthy speakers or acute ischaemic stroke patients, where the region most directly related to word retrieval appears to be the posterior part of the left temporal lobe. To clarify the neural basis of word retrieval in temporal lobe epilepsy, we tested forty-three drug-resistant temporal lobe epilepsy patients (28 left, 15 right). Comprehensive neuropsychological and language assessments were performed. Single spoken word production was elicited with picture or definition stimuli. Detailed analysis allowed the distinction of impaired word retrieval from other possible causes of naming failure. Finally, the neural substrate of the deficit was assessed by correlating word retrieval performance and resting-state brain metabolism in 18 fluoro-2-deoxy-d-glucose-Positron Emission Tomography. Naming difficulties often resulted from genuine word retrieval failures (anomic states), both in picture and in definition tasks. Left temporal lobe epilepsy patients showed considerably worse performance than right temporal lobe epilepsy patients. Performance was poorer in the definition than in the picture task. Across patients and the left temporal lobe epilepsy subgroup, frequency of anomic state was negatively correlated with resting-state brain metabolism in left posterior and basal temporal regions (Brodmann's area 20-37-39). These results show the involvement of posterior temporal regions, within a larger antero-posterior-basal temporal network, in the specific process of word retrieval in temporal lobe epilepsy. A tentative explanation for these findings is that epilepsy induces functional deafferentation between anterior temporal structures devoted to semantic processing and neocortical posterior temporal structures devoted to lexical processing.

Deficits in the left inferior longitudinal fasciculus results in impairments in object naming.

The functional characteristics of the left inferior longitudinal fasciculus (ILF) remain unclear. The present study describes a case of a right-handed 74-year-old woman with a brain tumor who showed marked deterioration in object naming ability after invasion of the tumor into the medial region of the left posterior (middle and inferior) temporal lobe just beside the atrium of the lateral ventricle. Diffusion tensor imaging showed possible interruption of the left ILF after invasion of tumor at this site. By contrast, the left superior longitudinal fasciculus (SLF) remained intact after invasion of tumor, and the inferior fronto-occipital fasciculus (IFOF) was already disrupted prior to tumor invasion. These observations indicate that intact ILF function may be required for object naming ability.

Severity of post-stroke aphasia according to aphasia type and lesion location in Koreans.

To determine the relations between post-stroke aphasia severity and aphasia type and lesion location, a retrospective review was undertaken using the medical records of 97 Korean patients, treated within 90 days of onset, for aphasia caused by unilateral left hemispheric stroke. Types of aphasia were classified according to the validated Korean version of the Western Aphasia Battery (K-WAB), and severities of aphasia were quantified using WAB Aphasia Quotients (AQ). Lesion locations were classified as cortical or subcortical, and were determined by magnetic resonance imaging. Two-step cluster analysis was performed using AQ values to classify aphasia severity by aphasia type and lesion location. Cluster analysis resulted in four severity clusters: 1) mild; anomic type, 2) moderate; Wernicke's, transcortical motor, transcortical sensory, conduction, and mixed transcortical types, 3) moderately severe; Broca's aphasia, and 4) severe; global aphasia, and also in three lesion location clusters: 1) mild; subcortical 2) moderate; cortical lesions involving Broca's and/or Wernicke's areas, and 3) severe; insular and cortical lesions not in Broca's or Wernicke's areas. These results revealed that within 3 months of stroke, global aphasia was the more severely affected type and cortical lesions were more likely to affect language function than subcortical lesions.

What Cognitive Neurology Teaches Us about Our Experience of Color.

Color provides valuable information about the environment, yet the exact mechanisms explaining how colors appear to us remain poorly understood. Retinal signals are processed in the visual cortex through high-level mechanisms that link color perception with top-down expectations and knowledge. Here, we review the neuroimaging evidence about color processing in the brain, and how it is affected by acquired brain lesions in humans. Evidence from patients with brain-damage suggests that high-level color processing may be divided into at least three modules: perceptual color experience, color naming, and color knowledge. These modules appear to be functionally independent but richly interconnected, and serve as cortical relays linking sensory and semantic information, with the final goal of directing object-related behavior. We argue that the relations between colors and their objects are key mechanisms to understand high-level color processing.

Speech and Language Presentations of FTLD-TDP Type B Neuropathology.

Four right-handed patients who presented with an isolated impairment of speech or language had transactive response DNA-binding protein of 43 kDa (TDP-43) type B pathology. Comportment and pyramidal motor function were preserved at presentation. Three of the cases developed axial rigidity and oculomotor findings late in their course with no additional pyramidal or lower motor neuron impairments. However, in all 4 cases, postmortem examination disclosed some degree of upper and lower motor neuron disease (MND) pathology in motor cortex, brainstem, and spinal cord. Although TDP-43 type B pathology is commonly associated with MND and behavioral variant frontotemporal dementia, it is less recognized as a pathologic correlate of primary progressive aphasia and/or apraxia of speech as the presenting syndrome. These cases, taken together, contribute to the growing heterogeneity in clinical presentations associated with TDP pathology. Additionally, 2 cases demonstrated left anterior temporal lobe atrophy but without word comprehension impairments, shedding light on the relevance of the left temporal tip for single-word comprehension.

Grammatical dissociation during acquired childhood aphasia.

AIM: We report the case of a 6-year-old female who suffered a left hemisphere stroke attributed to a genetically determined prothrombotic state. She presented a fluent speech pattern with selective difficulty in retrieving names but not verbs. An evaluation was designed to clarify whether her symptoms represented a specific impairment of name retrieval. METHOD: The child undertook an experimental battery of visual naming tasks requiring the production of 52 nouns (belonging to nine different semantic categories) and 44 verbs. Her performance was compared with that of 12 healthy children, matched for age and IQ, attending a local kindergarten. RESULTS: The child retrieved significantly more verbs than nouns (chi(2)=16.27, p<0.01) and had a significantly lower score in noun (t=-7.2, p<0.005), but not in verb retrieval than the comparison group. This pattern persisted when verbs and nouns were matched for oral word frequency, showing that the results could not be explained by stimuli difficulty. INTERPRETATION: To our knowledge, this is the first report of a grammatical dissociation in a child. It suggests that nouns and verbs are subject to different processing early in development, at least before the formal acquisition of grammar. It contradicts theories that postulate a common processing of different grammatical categories early in life.

Dysnomia, ataxia, choreoathetosis, sensory impairment, and gait imbalance after lentiform nucleus stroke.

We describe a patient in whom dysnomia, ataxia, choreoathetosis, sensory impairment, and severe gait imbalance resulted from an isolated left lentiform nucleus-posterior limb of internal capsule lacunar stroke. Each of these deficits has been described as a consequence of unilateral basal ganglia or internal capsule infarction in prior reports, but the combination of these findings in one patient is unusual. Accurate localization of the lesion to the anterior circulation has potential therapeutic implications.

Selection for sentence generation in the context of severe anomia: A case series of left temporal patients.

INTRODUCTION: Anomia is an impairment of naming: the retrieval of specific lexical items from the mental lexicon. Theoretically, whether anomia reflects a failure of selection at the preverbal "idea" level or at the subsequent linguistic formulation stage remains a topic of debate. We investigated the preverbal mechanism of idea selection for sentence generation, which requires the selection of a proposition from among competing alternatives during message formulation, in patients with severe anomia. METHOD: Patients with lesions to the left temporal lobe (N = 12), presenting with clinically defined anomia, and matched healthy controls (N = 24) completed sentence-level tasks that required the oral generation of a sentence or single word when presented with a word, a word pair, or a sentence. Selection demands were manipulated so that the stimuli activated many competing response options (low constraint) or one dominant or few response options (high constraint). RESULTS: There was no effect of stimuli constraint in the patient group that differed from that in the healthy control group on any of the generation tasks, suggesting that idea-level selection is intact in the patient group. CONCLUSIONS: These findings have implications for theoretical models of spoken language production and for clinical treatments of anomia.

Homographic and heterographic homophones in speech production: does orthography matter?

This paper investigates homophone naming performance in an individual with impaired word retrieval. The aim of the study is to investigate the status of homophone representations using treatment of homophone picture naming in aphasia. The focus of this paper is the representation of heterographic homophones (words which sound the same but are spelled differently, e.g., 'knight' vs. 'night'). Additionally, we replicate and expand previous findings regarding homographic homophones of Biedermann and Nickels (2008) in English and Biedermann et al. (2002), in German. Two theoretical positions about the mental representation of homophones are tested. First, do homophones - regardless of whether they are spelled the same or differently - share a phonological word form (e.g., Levelt et al., 1999; Dell, 1990)? Or second, do they have independent phonological word forms? (e.g., Caramazza et al., 2001; Miozzo and Caramazza, 2005)? In addition, might it be the case that homographic and heterographic homophones behave differently in word production reflecting different word form representations? These theoretical accounts are put to the test by looking at the generalisation of improvement following the treatment of homophone naming in aphasia, in particular, whether picture naming improves for both homophone meanings if only one is treated using a phonological cueing hierarchy. Treated and untreated homophones improved significantly, regardless of their spelling. Homographic and heterographic homophones showed the same pattern of generalisation. There was no generalisation for phonologically related controls. The pattern of generalisation extends our previous findings (Biedermann et al., 2002; Biedermann and Nickels, 2008) by showing evidence that heterographic homophones benefit to the same extent as homographic homophones. These results are interpreted as favouring a theory where both homographic and heterographic homophones share a single phonological representation. It is inferred that facilitation of naming takes place at the level of phonological representations, where orthography seems to have no influence.

Abeta amyloid deposition in the language system and how the brain responds.

Post-mortem measures of Abeta amyloid deposition correlate only weakly with cognitive dysfunction antemortem. We tested the hypothesis that functional reorganization forms a critical intermediary step between Abeta amyloid-associated brain injury and clinical disease expression. Fifteen patients with early-stage probable Alzheimer's disease (AD) and 16 cognitively intact controls participated in this combined functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) study. The fMRI design had two factors: task (associative-semantic versus visuoperceptual judgement) and input-modality (written words versus pictures). We measured Abeta amyloid by means of Pittsburgh Compound B (11C-PIB). In the posterior third of the left superior temporal sulcus (STS), the fMRI response during the associative-semantic compared with the visuoperceptual task was lower in AD than in controls, in particular for words. Response amplitude correlated inversely with PIB uptake in this region. Contralaterally, the functional pattern differed substantially: the fMRI response in the right posterior STS during the associative-semantic versus the visuoperceptual task was higher in AD than in controls. Accuracy on the Boston Naming test correlated positively with the degree to which AD patients were able to recruit the right STS (r = 0.84, P(corrected) = 0.014). PIB uptake did not correlate with naming accuracy. Functional reorganization of the language system in response to Abeta amyloid-related brain injury exists in early-stage AD and determines the degree of anomia more than Abeta amyloid load per se does.

Cognitive consequences of the left-right asymmetry of atrophy in semantic dementia.

Semantic dementia (SD) is a condition in which atrophy to the anterior temporal lobes (ATL) produces a selective deterioration of conceptual knowledge. As this atrophy is always bilateral but usually asymmetrical, differences in performance of the two SD subgroups-with left > right (L > R) versus right > left (R > L) atrophy-constitute a major source of evidence regarding the roles of the left and right sides of this region. We explored this issue using large scale case-series methodology, with a pool of 216 observations of neuropsychological data from 72 patients with SD. Anomia was significantly more severe in the L > R subgroup, even when cases from the two subgroups were matched on severity of comprehension deficits. For subgroups matched on the degree of anomia, we show that asymmetry of atrophy also affected both the nature of the naming errors produced, and the degree of a semantic category effect (living things vs artefacts). A comparison across tasks varying in their loading on verbal and visual processing revealed a greater deficit in object naming for L > R cases and in a picture-based semantic association test for R > L cases; this held true whether severity across subgroups was controlled using pairwise matching or statistically via principal components analysis. Importantly, the size of our sample allowed us to demonstrate considerable individual variation within each of the L > R and R > L subgroups, with consequent overlap between them. Our results paint a clear picture of how asymmetry of atrophy affects cognitive performance in SD, and we discuss the results in terms of two mechanisms that could contribute to these differences: variation in the information involved in semantic representations in the left and right ATL, and preferential connectivity between each ATL and other more modality specific intra-hemispheric regions.