Assuming that patterns in memory are represented as two-dimensional arrays of local features, just as they are in primary visual cortices, pattern recognition can take the form of elastic graph matching (Lades et al., 1993 ). Neural implementation of this may be based on preorganized fiber projections that can be activated rapidly with the help of control units (Wolfrum, Wolff, Lücke, & von der Malsburg, 2008 ). Each control unit governs a set of projection fibers that form part of a coherent mapping. We describe a mathematical model for the ontogenesis of the underlying connectivity based on a principle of network self-organization as described by the Häussler system (Häussler & von der Malsburg, 1983 ), modified to be sensitive to pattern similarity and to support formation of multiple mappings, each under the command of a control unit. The process takes the form of a soft-winner-take-all, where units compete for the representation of maps. We show simulations for invariant point-to-point and feature-to-feature mappings.
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http://dx.doi.org/10.1162/NECO_a_00725 | DOI Listing |
Alzheimers Dement
December 2024
Douglas Research Centre/ McGill University, Montreal, QC, Canada.
Background: Altered neuronal timing and synchrony are biomarkers for Alzheimer's disease (AD) and correlate with memory impairments. Electrical stimulation of the fornix, the main fibre bundle connecting the hippocampus to the septum, has emerged as a potential intervention to restore network synchrony and memory performance in human AD and mouse models. However, electrical stimulation is non-specific and may partially explain why fornix stimulation in AD patients has yielded mixed results.
View Article and Find Full Text PDFNeurosci Biobehav Rev
December 2024
Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba R3E 0W2, Canada. Electronic address:
The paraventricular nucleus of the thalamus (PVT) is generating interest because evidence establishes a role for this midline thalamic nucleus in behavior. Early tracing studies demonstrated that afferent fibers from the PVT and limbic cortex converge with dopamine fibers within subcompartments of the ventral striatum. Subsequent tracing studies expanded on these observations by establishing that the PVT provides a dense projection to a continuum of striatal-like regions that include the nucleus accumbens and the extended amygdala.
View Article and Find Full Text PDFNMR Biomed
February 2025
Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.
This study aimed to develop an automatic segmentation method for brainstem fiber bundles. We utilized the brainstem as a seed region for probabilistic tractography based on multishell, multitissue constrained spherical deconvolution in 40 subjects from the Human Connectome Project (HCP). All tractography data were registered into a common space to construct a brainstem fiber cluster atlas.
View Article and Find Full Text PDFBrain Commun
November 2024
Department of Clinical Sciences, Diagnostic Radiology, Medical Faculty, Lund University, 221 85 Lund, Sweden.
Non-invasive evaluation of glymphatic function has emerged as a crucial goal in neuroimaging, and diffusion tensor imaging along the perivascular space (DTI-ALPS) has emerged as a candidate method for this purpose. Reduced ALPS index has been suggested to indicate impaired glymphatic function. However, the potential impact of crossing fibres on the ALPS index has not been assessed, which was the aim of this cross-sectional study.
View Article and Find Full Text PDFBrain Commun
December 2024
Division of Neurology, Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.
Following a unilateral post-chiasmal lesion of the geniculo-striate pathway, patients develop homonymous visual field defects. Using classical perimetry, patients with 'complete' homonymous hemianopia are unaware of stimuli in the affected hemifield. However, some show preserved vision in the affected hemifield in which the conscious perception of moving stimuli is preserved (Riddoch phenomenon).
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