What bilateral damage of the superior parietal lobes tells us about visual attention disorders in developmental dyslexia

Neuroimaging studies have identified the superior parietal lobules bilaterally as the neural substrates of reduced visual attention (VA) span in developmental dyslexia. It remains however unclear whether the VA span deficit and the deficits in temporal and spatial attention shifting also reported in dyslexic children reflect a unitary spatio-temporal deficit of attention - probably linked to general posterior parietal dysfunction- or the dysfunction of distinct attentional systems that relate to different neural substrates. We explored this issue by testing an adult patient, IG, with a specific damage of the bilateral superior parietal lobules after stroke, on tasks assessing the VA span as well as temporal and spatial attention shifting. IG demonstrated a very severe VA span deficit, but preserved temporal attention shifting. Exogenous spatial orientation shifting was spared but her performance was impaired in endogenous attention. The overall findings show that distinct sub-systems of visual attention can be dissociated within the parietal lobe, suggesting that different attentional systems associated with specific neural networks can be selectively impaired in developmental dyslexia.

Deficits in egocentric-updating and spatial context memory in a case of developmental amnesia

Patients with developmental amnesia usually suffer from both episodic and spatial memory deficits. DM, a developmental amnesic, was impaired in her ability to process self-motion (i.e., idiothetic) information while her ability to process external stable landmarks (i.e., allothetic) was preserved when no self-motion processing was required. On a naturalistic and incidental episodic task, DM was severely and predictably impaired on both free and cued recall tasks. Interestingly, when cued, she was more impaired at recalling spatial context than factual or temporal information. Theoretical implications of that co-occurrence of deficits and those dissociations are discussed and testable cerebral hypothesis are proposed.

Verb production during action naming in semantic dementia

In contrast with widely documented deficits of semantic knowledge relating to object concepts and the corresponding nouns in semantic dementia (SD), little is known about action semantics and verb production in SD. The degradation of action semantic knowledge was studied in 5 patients with SD compared with 17 matched control participants in an action naming task based on video clips. The pattern of errors, involving a huge proportion of generic verbs (e.g. "to remove" versus "to peel") relative to responses in control subjects, suggested a hierarchical, bottom-up deficit of action knowledge in SD patients. In addition, abnormal responses in patients consisted of verbs that were semantically related to the expected verbs produced by control subjects (e.g. "to undress" versus "to peel" for the action [To peel_orange]). This study suggests that, in SD, non-canonical responses to action naming reflect lack of both specificity and semantic relatedness relative to the expected responses.

LEARNING OUTCOMES

As a result of this activity, readers will recognize that semantic word knowledge disappears in semantic dementia using video clips of object-related actions. As a result of this activity, readers will discover that this semantic impairment followed a hierarchical pattern with the more specific verbs vanishing first.

CSF biomarkers in posterior cortical atrophy

OBJECTIVE

To describe CSF biomarker profiles in posterior cortical atrophy (PCA), which induces high-order visual deficits often associated with Alzheimer disease (AD) pathology, and relate these findings to clinical and neuropsychological assessment.

METHODS

This prospective observational study included 22 patients with PCA who underwent CSF biomarker analysis of total tau (t-tau), phosphorylated tau on amino acid 181 (p-tau181), and amyloid β (Aβ(42)). At group level, the CSF profiles of patients with PCA were compared to those of patients with typical AD and patients with other dementia (OD). Individually, the clinical presentation of patients with PCA was correlated to their CSF profile to assess the predictability of clinical features for diagnosis of underlying AD pathology.

RESULTS

At group level, the PCA biomarker profile was not different from that of the AD group, but very different from that of the OD group (p < 0.001). More than 90% of patients with PCA had CSF profiles consistent with AD. All patients with PCA with either isolated higher-order visual deficit (n = 8) or visual deficit associated with memory impairment (n = 11) had CSF profiles consistent with AD. Only one of the 3 patients with PCA with asymmetric motor signs fulfilled biological CSF criteria for AD.

CONCLUSIONS

PCA syndrome is usually associated with CSF biomarkers suggestive of AD, as shown by previous neuropathologic studies. This does not apply in case of motor signs suggesting associated corticobasal syndrome. CSF biomarkers help to discriminate AD from non-AD processes associated with this condition.

Mild Alzheimer's disease: a "position paper"

Under the auspices of the Societe Francaise de Geriatrie et Gerontologie, a multi-disciplinary group of specialists in geriatrics, neurology, epidemiology, psychiatry, neuroradiology and nuclear medicine met with the aim of drawing up references on the methods for diagnosing and treating mild Alzheimer's disease. The critical analysis of international literature, conducted by Professor Bruno Vellas for the scientific committee, has served to support study of the latest knowledge in 2008. The multi-disciplinary group met on 14 and 15 May 2008 in order to set out the questions that this study must answer and to allocate draft studies. Thus, it has been possible to conduct a study focused on mild Alzheimer's disease, giving particular attention to diagnostic procedure, specific methods of treatment and the benefits of making a diagnosis.

Cortico-responsive encephalopathy associated with autoimmune thyroiditis (SREAT): about two case reports characterized by a gap between the diagnosis of autoimmune thyroiditis and neurological disorders

We report two cases of steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT) often called "Hashimoto's encephalopathy" in which the neurological manifestations develop years before or after the Hashimoto's diagnosis. Because of this specific presentation, the etiological diagnosis of this type of encephalopathy can be a difficult task. In our patients there was a gap of 10 to 20 years between the proof of autoimmune thyroiditis and the neurological symptoms. Case reports of this type of presentation are rare in the literature. A dramatic responsiveness to steroids with total recovery, after several relapses, was confirmed 3 years after the end of treatment. We suggest that antithyroid antibodies should be checked in all patients with unexplained acute or subacute encephalopathy even in elderly subjects in whom the most important differential diagnosis with Creutzfeldt-Jacob disease remains rapidly progressive Alzheimer's disease. A brief review of the literature is proposed.

Influence of motor disorders on the visual perception of human movements in a case of peripheral dysgraphia

We report the case of a 71 year-old female patient (DC) with a left parietal lesion resulting in a peripheral dysgraphia essentially characterized by difficulties in letter sequences writing. The aim of our experiments was to analyze the influence of motor difficulties on the visual perception of both writing and reaching movements. Results showed a strong link between motor and perceptual performance. For reaching movements, performances in both production and perception tasks conform to the motor principles identified in healthy subjects (Fitts' law and motor anticipation). By contrast, for handwriting movements, DC's productions do not follow the motor principles usually observed in normal subjects (isochrony principle, motor anticipation) and in perception the same results were observed. The motor references used by DC in the visual perception of writing movement were not the laws of movement but rather her own way of writing. Taken together these data strongly suggest that motor competences is involved in the visual perception of human movements. They are discussed in the general framework of the simulation theory.

Are semantic errors actually semantic?: Evidence from alzheimer's disease

Patients with Alzheimer's disease (AD) produce a high rate of semantic errors when naming to confrontation. This is considered to be one of the many consequences of their semantic memory deficit. However, it has been shown, in aphasic patients with focal lesions, that semantic errors could arise from impairment to any one of the levels in the naming process. To check this hypothesis in AD, we assessed in 15 patients the capacity to name and access semantic knowledge (by multiple-choice probe questions) about 14 objects presented successively in the visual, tactile, auditory, and verbal modalities. In the visual naming task, 33 errors were recorded: 26 (78.8%) were semantic and 7 (21.2%) were unrelated errors. Of the 26 semantic errors, 8 were related to a deficit of the semantic knowledge related to the item and 17 to a deficit in the retrieval of the phonological form of the word. One was associated with a deficit of access to semantic knowledge in the visual modality. The 7 unrelated errors were associated with a loss of semantic knowledge for 4 and deficit of access to the phonological form for 3. In conclusion, this study shows that semantic errors do not systematically reflect a deficit of semantic knowledge in Alzheimer's disease. It also seems that unrelated errors are more frequently related to semantic deficits than semantic errors in this population.

Superior written over spoken picture naming in a case of frontotemporal dementia

Two main hypotheses have been proposed regarding the role of phonology in written word production. According to the phonological mediation hypothesis, the retrieval of the lexical phonological representation of a word is an obligatory prerequisite to the retrieval of its spelling. Therefore, deficits to the phonological lexicon should affect both spoken and written picture naming. In contrast, the orthographic autonomy hypothesis posits that the lexical orthographic representations of words can be accessed without any necessary phonological mediation. In support of this view, cases of preserved written naming despite impaired lexical phonology have been reported following brain damage. In this report, we replicate this basic pattern of performance in case YP, a 60-year-old woman with a pattern of frontotemporal dementia. As her disease progressed, YP's ability to write down the names of pictures remained very good despite a severe decline in oral naming. Further testing indicated that this deficit was not primarily due to an articulatory or post-lexical phonological deficit. YP's case provides strong additional support for the orthographic autonomy hypothesis. The significance of this case with respect to the characterization of dementia syndromes is discussed.

Working memory functioning in medicated Parkinson's disease patients and the effect of withdrawal of dopaminergic medication

Cognitive impairments in Parkinson's disease (PD) could be explained by a central executive (CE) deficit in A. D. Baddeley's (1986) working memory model. To test this hypothesis, verbal, spatial, and double span tasks were given to 12 medicated PD patients and control participants, with varying recall delays. The double span task was assigned to explore the coordinating and integrating function of the CE, and lengthening the recall delay was expected to implicate more attentional resources. PD patients had lower spans relative to controls in all tasks. However, the more specific implication of the CE was difficult to prove. One reason could be that PD patients were on dopaminergic treatment when tested. To control this effect, 12 PD patients on and off medication were studied in a second experiment using the same tasks. PD patients off medication had lower spans only in the double task; this result underlines the role of dopamine on working memory processes.

Working memory functioning in medicated Parkinson's disease patients and the effect of withdrawal of dopaminergic medication

Cognitive impairments in Parkinson's disease (PD) could be explained by a central executive (CE) deficit in A. D. Baddeley's (1986) working memory model. To test this hypothesis, verbal, spatial, and double span tasks were given to 12 medicated PD patients and control participants, with varying recall delays. The double span task was assigned to explore the coordinating and integrating function of the CE, and lengthening the recall delay was expected to implicate more attentional resources. PD patients had lower spans relative to controls in all tasks. However, the more specific implication of the CE was difficult to prove. One reason could be that PD patients were on dopaminergic treatment when tested. To control this effect, 12 PD patients on and off medication were studied in a second experiment using the same tasks. PD patients off medication had lower spans only in the double task; this result underlines the role of dopamine on working memory processes.

Neuropsychological functioning among non-psychotic siblings and parents of schizophrenic patients

Several studies have shown subtle neuropsychological deficits in healthy relatives of schizophrenic patients. However, older relatives and parents have been less frequently assessed than younger adult relatives and siblings. Furthermore, some areas of neuropsychological functioning such as memory and learning have been little studied. Thirty-seven 22-70-year-old non-psychotic parents and siblings of schizophrenic patients were compared to 37 healthy control subjects on a battery of neuropsychological tests (Trail Making, parts A and B, verbal fluency, Wisconsin Card Sorting Test, and four subtests of the Wechsler Memory Scale-Revised: logical memory, design reproduction, verbal paired associates and digit span). Relatives did not differ from control subjects on Wisconsin Card Sorting Test performance and on visual memory, but were significantly impaired on verbal fluency; more subtle deficits were found on Trail Making, part B, digit span and paired associates. A higher proportion of relatives than control subjects showed impairment on verbal fluency and verbal memory. These neuropsychological weaknesseswere present as much in siblings as in parents of schizophrenic patients, and age did not cancel differences between relatives and control subjects. Thus, these subtle deficits seem to be potential phenotypic markers of schizophrenia.

Identification without manipulation: a study of the relations between object use and semantic memory

The role of semantic knowledge in object utilisation is a matter of debate. It is usually presumed that access to semantic knowledge is a necessary condition for manipulation, but a few reports challenged this view. The existence of a direct, pre-semantic route from vision to action has been proposed. We report the case of a patient with a disorder of object use in everyday life, in the context of probable Alzheimer's disease. This patient was also impaired when manipulating single objects. He showed a striking dissociation between impairment in object use and preserved capacity to perform symbolic and meaningless gestures. To elucidate the nature of the disorder, and to clarify the relations between semantic knowledge and object use, we systematically assessed his capacity to recognise, name, access semantic knowledge, and use 15 common objects. We found no general semantic impairment for the objects that were not correctly manipulated, and, more importantly, no difference between the semantic knowledge of objects correctly manipulated and objects incorrectly manipulated. These data, although not incompatible with the hypothesis of a direct route for action, are better accommodated by the idea of a distributed semantic memory, where different types of knowledge are represented, as proposed by Allport (Allport, D. A. Current perspectives in dysphasia, pp. 32-60. Churchill Livingstone, Edinburgh, 1985).

[Absence of frontal lobe dysfunction and working memory deficits in young schizophrenic patients]

The impairment in tasks requiring intact frontal lobe functions has been repeatedly shown in schizophrenics. However, the relative roles of confounding factors, like duration of the disease, social withdrawal, or antidopaminergic medication, are not clearly demonstrated. We studied the performance of 12 young active patients, with chronic residual schizophrenia that had recent onset, and 12 control subjects, with frontal lobe tests and with a battery designed to explore working memory. The results show normal performance in schizophrenia. The small number of patients does not allow definitive conclusions, but this study suggests that a frontal dysfunction may not be present early in the evolution of schizophrenia in active patients.

The phonological loop in medicated patients with Parkinson's disease: presence of phonological similarity and word length effects

OBJECTIVE

To test the verbal subsystem of Baddeley's working memory model (the phonological loop) in patients with Parkinson's disease.

METHODS

Fifteen patients with idiopathic Parkinson's disease and 15 controls were tested with a span paradigm to assess the effects reflecting the functioning of the phonological loop: the phonological similarity effect (in verbal and visual presentation), and the word length effect (in visual presentation).

RESULTS AND CONCLUSIONS

The patients did not show any dysfunction of the phonological loop, reflected by the presence of phonological similarity and word length effects, but had lower spans than controls. The implications of these results for the working memory model are discussed.

Apolipoprotein E and Alzheimer disease: genotype-specific risks by age and sex

The distribution of apolipoprotein E (APOE) genotypes as a function of age and sex has been examined in a French population of 417 Alzheimer disease (AD) patients and 1,030 control subjects. When compared to the APOE epsilon3 allele, an increased risk associated with the APOE epsilon4 allele (odds ratio [OR] [epsilon4] = 2.7 with 95% confidence interval [CI] = 2.0-3.6; P < .001) and a protective effect of the APOE epsilon2 allele (OR[epsilon2] = 0.5 with 95% CI = 0.3-0.98; P = .012) were retrieved. An effect of the epsilon4 allele dosage on susceptibility was confirmed (OR[epsilon4/epsilon4] vs. the epsilon3/epsilon3 genotype = 11.2 [95% CI = 4.0-31.6]; OR[epsilon3/epsilon4] vs. the epsilon3/epsilon3 genotype = 2.2 [95% CI = 1.5-3.5]). The frequency of the epsilon4 allele was lower in male cases than in female cases, but, since a similar difference was found in controls, this does not lead to a difference in OR between sex. ORs for the epsilon4 allele versus the epsilon3 allele, OR(epsilon4), were not equal in all age classes: OR(epsilon4) in the extreme groups with onset at < 60 years or > 79 years were significantly lower than those from the age groups 60-79 years. In epsilon3/epsilon4 individuals, sex-specific lifetime risk estimates by age 85 years (i.e., sex-specific penetrances by age 85 years) were 0.14 (95% CI 0.04-0.30) for men and 0.17 (95% CI 0.09-0.28) for women.

[Marchiafava-Bignami disease: development with flare-up]

Marchiafava-Bignami disease is a complication of chronic ethanol intoxication. The clinical course may be acute, rapidly leading to death, or marked by a progressive dementia. A form with favorable outcome is also described. During the evolution of chronic forms, acute worsenings are possible, with subsequent partial recovery. We report a clinico-radiological case, where a first episode was followed by a good outcome. After a second episode, 3 years later, the patient developed a dementia with predominant frontal lobe signs. This case suggests that, even after a favorable outcome, a long-term poor prognosis cannot be ruled out.

[Capillary and cavernous hemangioma disclosed by painful amyotrophy of the thigh]

We report the case of an intramuscular cavernous and capillary hemangioma of the thigh revealed by pains evolving for 2 years and by an amyotrophy. After 21 months of investigation, the surgical excision and the histological examination only established the dia Thigh MRI. T1-weighted axial and sagittal sections with gadolinium infusion.

Working memory in medicated patients with Parkinson's disease: the central executive seems to work

OBJECTIVE

To determine whether a deficit of the central executive can explain the attentional deficits of patients with Parkinson's disease.

METHODS

Fifteen patients with idiopathic Parkinson's disease and 15 controls were given a dual task paradigm minimising motor demands and combining verbal, visual, or spatial span with two conditions of articulatory suppression.

RESULTS

Although the spans were systematically lower in medicated parkinsonian patients than in controls, suggesting a decrease of central processing resources, there was no direct evidence for a deficit of the central executive.

CONCLUSIONS

A deficit of the central executive either is not an inevitable feature of the disease, or is dependent on the nature of task (visuomotor v cognitive), or is corrected by dopaminergic medication.

[Frontal lobe dysfunction and depressive state: relation to endogenous character of depression]

A dysfunction of dorsolateral prefrontal cortex (DLPF) in major depression is suggested by functional imagery and comparative neuropsychology. However, assessment of frontal lobe syndrome with DLPF-dependent tests led to controversial results. To clarify these findings, we administered 5 of these tests (Wisconsin Card Sorting Test, Stroop Test, Trail Making Test, Tower of Toronto, verbal fluency) to 16 major depressive subjects and their 16 controls, before and after 21 days of treatment. Furthermore, we tried to assess the prognostic value of frontal lobe dysfunction, and its relation with the endogenous or exogenous nature of the depression on the one hand, the severity of the depression on the other hand. Our results suggest that the presence of a frontal lobe syndrome (defined by impaired performances at 3 tests or more) is only noted in endogenous depression; after treatment, no impairment is detected. No correlation is found with the severity of the depression. Frontal lobe syndrome does not seem to indicate poorer prognosis for current depressive episode.

[Deficiency in the reproduction and learning proper names after left tubero-thalamic ischemic lesion]

Predominant impairment or preservation of category-specific naming and comprehension is not rare in aphasics. Much less frequent is a selective inability to generate proper names. To our knowledge, only one such case has been reported after a left thalamic lesion, located in the ventral anterior nucleus, the mamillo-thalamic tractus and the genu of the internal capsule. We report a new case of selective inability to generate proper names after a left tubero-thalamic infarct. A 65-year old right-handed man presented with a selective impairment in producing proper names, both from photographs or descriptions and on tests of verbal fluency. The deficit was obvious both for persons names and for geographical names. The rest of the neuropsychological testing was remarkable only for a mild verbal amnesia, affecting only serial material (list of words), a reduced fluency for flowers, fruits and musical instruments, difficulties in learning of new words, and a dissociation between preserved learning for words on a test of learning of words and occupations (Cohen, 1990). This anomia for proper names could result from an indirect frontal-lobe dysfunction, preventing voluntary activation of the phonological representation of proper names.