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O Felician

Publications and source records attributed to O Felician.

9 recordsLinked to original sources
PubMed2004

Progressive prosopagnosia: clinical and neuroimaging results.

The authors report the longitudinal case study of a patient with the right temporal variant of frontotemporal lobar degeneration. His deficit, initially limited to visuoperceptual disturbances, progressed 2 years later to a severe semantic breakdown. Neuroimaging data indicate that the underlying degenerative process, initially confined to unimodal visual associative cortices, progressed along the ventral pathways to multimodal areas in charge of integrating knowledge from various modalities (the anterior temporal lobes).

Aged↗
PubMed2004

Evaluation of visual recognition memory in MCI patients.

BACKGROUND: Neurofibrillary tangles seen early in Alzheimer disease (AD) initially appear in a subregion of the perirhinal cortex. In the monkey, damage to the perirhinal cortex impairs performance on visual recognition memory tasks. The authors evaluated impairment of visual recognition memory as a potential early diagnostic marker of AD. METHODS: The authors developed a visual delayed matching-to-sample task (DMS48) designed to assess visual recognition memory in humans. Twenty-three patients fulfilling the criteria of amnestic mild cognitive impairment (MCI) (mean Mini-Mental State Examination [MMSE]: 26.6, SD = 1.6) were recruited. All underwent a full neuropsychological evaluation, which included the Free and Cued Selective Reminding (FCSR) test. Their performance was compared with that of 10 patients with mild AD, 20 patients with moderate AD, 20 patients with Parkinson disease (PD), and 40 age-matched controls. RESULTS: Control subjects and patients with PD performed close to ceiling. Patients with mild AD had very low scores, while patients with moderate AD answered at random. MCI patients obtained scores that were between those of control subjects and patients with mild AD (78%, SD = 16%). MCI patients who failed on the DMS48 had lower scores on free recall (p < 0.05) and received less benefit from cueing (p < 0.01) on the FCSR than the other MCI, suggesting a profile of genuine memory impairment related to medial temporal lobe lesions. CONCLUSION: The DMS48, a test of visual recognition memory, is impaired early in the course of patients with MCI. Further studies are necessary to determine whether the evaluation of visual recognition memory may contribute to the identification of patients with AD.

Aged↗
PubMed2004

[The human perirhinal cortex].

The perirhinal cortex is a structure that lies within the medial temporal lobe. In the present paper, we review current knowledge of the anatomical boundaries and functional correlates of this structure. In the past decade, numerous animal studies have attempted to understand the contribution of the perirhinal cortex to memory. Taken together, they suggest that the perirhinal cortex is crucially involved in recognition memory. This function appears to be independent from those assumed to be subserved by the hippocampus. In humans, data are scarce but tend to corroborate results found in the animal literature. The perirhinal cortex appears to support context-free (non-episodic) knowledge, such as general knowledge about the world and "item-specific" memories. Models of declarative memory that take into account the specific contribution of the perirhinal cortex are discussed, along with their potential application to early cortical neurodegenerative disorders.

Animals↗
PubMed1999

The role of area 17 in visual imagery: convergent evidence from PET and rTMS.

Visual imagery is used in a wide range of mental activities, ranging from memory to reasoning, and also plays a role in perception proper. The contribution of early visual cortex, specifically Area 17, to visual mental imagery was examined by the use of two convergent techniques. In one, subjects closed their eyes during positron emission tomography (PET) while they visualized and compared properties (for example, relative length) of sets of stripes. The results showed that when people perform this task, Area 17 is activated. In the other, repetitive transcranial magnetic stimulation (rTMS) was applied to medial occipital cortex before presentation of the same task. Performance was impaired after rTMS compared with a sham control condition; similar results were obtained when the subjects performed the task by actually looking at the stimuli. In sum, the PET results showed that when patterns of stripes are visualized, Area 17 is activated, and the rTMS results showed that such activation underlies information processing.

Adult↗
PubMed1999

The neurobiology and pharmacotherapy of Alzheimer's disease.

Alzheimer's disease (AD), the most common cause of dementia, has become a major public health concern as our population ages. In recent years, AD has attracted the attention of a wide range of biological disciplines, and substantial progress has been made in understanding the mechanisms of neurodegeneration in AD. Four different genes have now been associated with AD and are providing insights into the pathogenesis of the disease. The roles of beta-amyloid, tau, hormonal changes, inflammation, and oxidative stress in the neurodegeneration of AD are also being delineated. Based on these discoveries, rational therapeutic strategies are developing rapidly. The authors review these and other recent advances in the neurobiology and pharmacotherapy of AD.

Acetylcholine↗
PubMed1999

[Progressive focal cortical atrophies].

Progressive focal cortical atrophies are degenerative conditions characterised by the insidious onset and gradual exacerbation of an impairment in a single cognitive domain related to circumscribed cerebral atrophy. Several focal cortical syndromes with deficits in the realm of cognition are reviewed: progressive impairment of language (primary progressive aphasia), speech (progressive anarthria), semantic memory (semantic dementia), episodic memory (pure progressive amnesia), vision (progressive perceptual or visuo-spatial deficits) and gesture (progressive apraxia). These conditions are histologically heterogeneous and can be associated with focal non-specific neuronal loss and gliosis with some spongiform changes (non-specific lesions), pathological features of Pick's disease (inclusion bodies and swollen neurones) or Alzheimer's disease (AD) (senile plaques and neurofibrillary tangles). A relationship between neuropsychological profiles and lesional types emerges from this review of the literature. Non-fluent primary progressive aphasia, semantic dementia and progressive anarthria are usually associated with non-specific lesions and Pick-type pathology. Progressive disorders of episodic memory and progressive visuo-spatial deficits are more often related to AD. If adequate clinical characterisation can determine the underlying disorder, it appears even more important to establish the neuropsychological profile in patients with cortical degenerative disease. Progressive deficits of only one domain of cognition may well be due to preferential involvement of anatomically and functionally defined neural systems and could therefore be considered as "system atrophies". There remains no doubt that these syndromes are particularly well suited models for studies on the relationship between cerebral functions and their neural substrate.

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PubMed1998

The potential application of cyclo-oxygenase type 2 inhibitors to Alzheimer's disease.

In recent years, dramatic progress has been made in the understanding of the neurogenetics and neurobiology of Alzheimer's disease (AD). A great deal of experimental evidence has accumulated to support the hypothesis that inflammatory mechanisms are involved in the pathophysiology of AD. In addition, epidemiological studies have revealed that anti-inflammatory medications reduce the risk of developing AD. However, long-term use of conventional anti-inflammatory drugs is associated with significant toxicity which limits their potential application to the treatment or prevention of AD. It is believed that the inhibition of cyclo-oxygenase type-1 (COX-1) causes much of this toxicity, while inhibition of COX type-2 (COX-2), which is induced by inflammatory stimuli, may confer the anti-inflammatory effect. COX-2 is also constitutively expressed in brain regions preferentially affected in Alzheimer's disease and may be directly involved in neuronal cell death. Therefore, selective COX-2 inhibitors represent a promising class of drugs for the treatment of AD.

Journal Article↗
PubMedDate not supplied

Diffusion-weighted magnetic resonance imaging in Alzheimer's disease.

Diffusion-weighted imaging (DWI) is a powerful new magnetic resonance imaging technique for evaluating tissue pathophysiology in vivo. We performed DWI in three orthogonal spatial directions in 10 patients with mild to moderate Alzheimer's disease (AD) and 11 control subjects. Average apparent diffusion coefficients (ADCavg) were calculated for gray matter regions, and anisotropy indexes were calculated for white matter regions. Global measures of atrophy and white matter hyperintensities (WMH) were obtained on T2-weighted images to control for their potential confounding effects on ADCavg and anisotropy. The measures of atrophy and WMH differed between the groups and were used as covariates in the subsequent statistical analyses. Patients with AD demonstrated diminished anisotropy in the posterior white matter (p < 0.0001) and increased ADCavg in the hippocampus (p < 0.05) when compared to the control group. Diffusion measures did not correlate with the severity of dementia. DWI provides a unique, quantitative parameter that may be sensitive to the pathophysiological and/or microstructural abnormalities that occur in AD.

Aged↗