Hemispheric asymmetry, modular variability and age-related changes in the human entorhinal cortex

Šimić, Goran; Bexheti, Sadi; Kelović, Zlatko; Kos, Mladen; Grbić, Kristina; Hof, Patrick R.; Kostović, Ivica

doi:10.1016/j.neuroscience.2004.09.040

Cited by 54 publications

(52 citation statements)

References 69 publications

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“…That fi nding is in accordance with the hemispheric asymmetries recently described in the human entorhinal cortex, a brain region that projects to the hippocampal formation, where leftward size predominance was found 40 . Besides, as the left dentate gyrus contains fewer granule cells than the right one 8 , we may hypothesize that the higher number of dendritic segments that we found in the left side might somewhat compensate for this difference.…”

Section: Discussionsupporting

confidence: 91%

Dendritic right/left asymmetries in the neurons of the human hippocampal formation: a quantitative Golgi study

Sá

Ruela

Madeira

2007

Arq. Neuro-Psiquiatr.

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-Objective: To search for right/left asymmetries in the dendritic trees of the neuronal populations and in the cell-free layer volumes of the human hipoccampal formation. Method: In necropsic material obtained from six male individuals we performed a quantitative Golgi study of the dendritic trees of dentate granules, CA3 and CA1 pyramidal neurons and a volumetric analysis of dentate gyrus molecular layer, strata oriens plus alveus and strata lacunosum-moleculare plus radiatum of CA3 and CA1 fields. Results: We found inter-hemispheric asymmetries in the dendrites trees of all neurons, reaching the significant level in the number of granule cells dendritic segments (higher in the left than in the right hemisphere), dendritic branching density of CA3 pyramidal cells and mean dendritic length of CA1 apical terminal segments (higher in the right than in the opposite side). No volumetric differences were observed. Conclusion: This study points to different anatomical patterns of connectivity in the hippocampal formations of both hemispheres which may underlie functional asymmetries.KEY WORDS: brain asymmetries, hippocampal formation, dendritic asymmetries. Assimetrias dendríticas direita/esquerda nos neurónios da formação do hipocampo humano: estudo quantitativo GolgiRESUMO -Objectivo: Pesquisar a existência de assimetrias direita/esquerda nas arborizações dendríticas neuronais e nos volumes das camadas não celulares da formação do hipocampo humano. Método: Efectuamos estudo quantitativo Golgi das arborizações dendríticas dos grânulos da fascia denteada e das células piramidais de CA3 e CA1, e uma análise estereológica dos volumes da camada molecular da fascia denteada, do strata oriens + alveus e do strata lacunosum-moleculare + radiatum de CA3 e de CA1 em material necrópsico colhido em 6 indivíduos do sexo masculino. Resultados: Encontrámos assimetrias inter-hemisféri-cas nas arborizações dendríticas de todos os neurónios, significativas no número de segmentos dendríticos das células granulares (maior à esquerda do que à direita) na densidade de ramificação dendrítica das pirâmides de CA3 e no comprimento dendrítico médio dos segmentos apicais terminais das pirâmides de CA1 (maiores à direita do que à esquerda). Não encontramos diferenças volumétricas. Conclusão: Estes resultados alertam para diferentes padrões anatómicos de conectividade nas formações do hipocampo de ambos os hemisférios que podem fundamentar assimetrias funcionais. PALAVRAS-CHAVE: assimetrias cerebrais, formação do hipocampo, assimetrias dendríticas. Porto -Portugal. E-mail: mjsa@med.up.pt The existence of anatomical inter-hemispheric asymmetries has since long been described in several regions of the normal human brain, mainly in those related to the processing of language functions [1][2][3][4] . In effect, most studies addressing this issue were centered in the neocortex where right/left differences were observed in macroscopic features, such as the shape and confi guration of cerebral sulci and specific cortical areas, as well as...

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Section: Discussionsupporting

confidence: 91%

Dendritic right/left asymmetries in the neurons of the human hippocampal formation: a quantitative Golgi study

Sá

Ruela

Madeira

2007

Arq. Neuro-Psiquiatr.

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“…On the contrary, other authors found that left LFC hypometabolism was a feature of stable MCI patients over time [16]. The left LFC contains the language areas and, moreover, is involved in working memory, episodic memory encoding and semantic memory retrieval [17,18]. Conversion to AD mainly entails a worsening episodic and working memory that significantly impairs the everyday functional autonomy, which is consistent with the idea that metabolic failure in these areas is a main PET hallmark of conversion.…”

Section: Fdg-pet Findings In Mild Cognitive Impairment (Mci) and Earlsupporting

confidence: 64%

[18F]FDG-PET as a Biomarker for Early Alzheimer`s Disease

Nobili¹,

Morbelli²

2010

TONMEDJ

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[18 Fluorine]fluorodeoxiglucose-Positron Emission Tomgraphy ( 18 F FDG-PET) has gained a leading role in the diagnostic assessment of patients with cognitive complaints, notably Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD). Together with morphological Magnetic Resonance Imaging (MRI) and cerebrospinal fluid biomarker assays it allows early identification of subjects with neurodegeneration of the AD-type, which is crucial in view of effective disease-modifying drugs.[18F]FDG-PET identifies hypometabolic regions in posterior cingulate-precuneus, posterior lateral and medial temporal-parietal association cortex, and in lateral frontal cortex. Hypometabolism in posterior cingulate-precuneus may be found even in MCI patients not yet converted to AD after a reasonable follow-up time and thus it might be a marker of memory deficit rather than of AD conversion. As [18F]FDG-PET is sensitive to synaptic dysfunction and depletion, hypometabolic areas can be detected before atrophy is highlighted by MRI in the same regions. The interpretation of the pathophysiological meaning of hypometabolism is discussed also in view of the most recent theory on the brain 'default mode network'. In longitudinal 1-year studies, [18F]FDG-PET has been shown an adequate tool to detect metabolic deterioration in AD patients better than amyloid-PET. It has been proposed as a surrogate biomarker to evaluate the effect of disease-modifying drugs in AD with a five times higher power than the commonly used neuropsychological scales. A flow-chart on the clinical use of [18F]FDG-PET is proposed, in which it is strongly recommended in MCI patients with suspected neurodegeneration.

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“…In normal healthy ageing, the global number of microglia [17] or neurons [18] does not decrease significantly. However, a significant decline in neuronal number was detected in several brain regions such as the subiculum and hilus regions of the hippocampus [19] and in the entorhinal cortex [20]. These changes correlate well with the severity of declarative memory decline [21].…”

Section: Functional Histological and Molecular Changes In The Ageingmentioning

confidence: 96%

The endocannabinoid system in normal and pathological brain ageing

Bilkei-Gorzó

2012

Phil. Trans. R. Soc. B

121

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The role of endocannabinoids as inhibitory retrograde transmitters is now widely known and intensively studied. However, endocannabinoids also influence neuronal activity by exerting neuroprotective effects and regulating glial responses. This review centres around this less-studied area, focusing on the cellular and molecular mechanisms underlying the protective effect of the cannabinoid system in brain ageing. The progression of ageing is largely determined by the balance between detrimental, proageing, largely stochastic processes, and the activity of the homeostatic defence system. Experimental evidence suggests that the cannabinoid system is part of the latter system. Cannabinoids as regulators of mitochondrial activity, as anti-oxidants and as modulators of clearance processes protect neurons on the molecular level. On the cellular level, the cannabinoid system regulates the expression of brainderived neurotrophic factor and neurogenesis. Neuroinflammatory processes contributing to the progression of normal brain ageing and to the pathogenesis of neurodegenerative diseases are suppressed by cannabinoids, suggesting that they may also influence the ageing process on the system level. In good agreement with the hypothesized beneficial role of cannabinoid system activity against brain ageing, it was shown that animals lacking CB1 receptors show early onset of learning deficits associated with age-related histological and molecular changes. In preclinical models of neurodegenerative disorders, cannabinoids show beneficial effects, but the clinical evidence regarding their efficacy as therapeutic tools is either inconclusive or still missing.

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Hemispheric asymmetry, modular variability and age-related changes in the human entorhinal cortex

Cited by 54 publications

References 69 publications

Dendritic right/left asymmetries in the neurons of the human hippocampal formation: a quantitative Golgi study

Dendritic right/left asymmetries in the neurons of the human hippocampal formation: a quantitative Golgi study

[18F]FDG-PET as a Biomarker for Early Alzheimer`s Disease

The endocannabinoid system in normal and pathological brain ageing

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