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Papageorgiou E.,University of Tübingen | Hardiess G.,Laboratory of Cognitive Neuroscience | Wietholter H.,Burgerhospital | Ackermann H.,Rehabilitation Center | And 3 more authors.
Acta Ophthalmologica | Year: 2012

Purpose: The aim of this study was to assess the brain regions associated with impaired performance in a virtual, dynamic collision avoidance task, in a group of patients with homonymous visual field defects (HVFDs) because of unilateral vascular brain lesions. Methods: Overall task performance was quantitatively assessed as the number of collisions while crossing an intersection at two levels of traffic density. Twenty-six patients were divided into two subgroups using the median split method: patients with 'performance above average' (HVFD A, i.e. lower number of collisions) and patients with 'performance below average' (HVFD B, i.e. higher number of collisions). In order to identify the anatomical structures that might be specifically affected in HVFD B patients but spared in HVFD A patients, overlap, subtraction and voxel-based lesion-symptom mapping analyses were performed using the MRIcron software. Results: No significant difference in collision avoidance between patients with left- and right-hemispheric lesions was revealed. Separate lesion analysis in 12 patients with right- and 14 patients with left-hemispheric lesions showed that the cortical structures associated with impaired collision avoidance were the parieto-occipital region and posterior cingulate gyrus in the right hemisphere and the inferior occipital cortex and parts of the fusiform (occipito-temporal) gyrus in the left hemisphere. Conclusion: In the present collision avoidance paradigm, impaired performance of patients with right-hemispheric lesions is associated with damage in the dorsal processing stream and potential impact on the visual spatial working memory (WM), while impaired performance of patients with left-hemispheric lesions is associated with damage in the ventral stream and potential impact on the visual object WM. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

PubMed | Laboratory of Cognitive Neuroscience
Type: | Journal: Behavioural brain research | Year: 2016

The entorhinal-hippocampal circuitry has been suggested to play an important role in episodic memory but the contribution of the entorhinal cortex remains elusive. Predominant theories propose that the medial entorhinal cortex (MEC) processes spatial information whereas the lateral entorhinal cortex (LEC) processes non spatial information. A recent study using an object exploration task has suggested that the involvement of the MEC and LEC spatial and non-spatial information processing could be modulated by the amount of information to be processed, i.e. environmental complexity. To address this hypothesis we used an object exploration task in which rats with excitotoxic lesions of the MEC and LEC had to detect spatial and non-spatial novelty among a set of objects and we varied environmental complexity by decreasing the number of objects or amount of object diversity. Reducing diversity resulted in restored ability to process spatial and non-spatial information in MEC and LEC groups, respectively. Reducing the number of objects yielded restored ability to process non-spatial information in the LEC group but not the ability to process spatial information in the MEC group. The findings indicate that the MEC and LEC are not strictly necessary for spatial and non-spatial processing but that their involvement depends on the complexity of the information to be processed.

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