Dynamic Formation of Self-Organizing Maps

International audienceIn this paper, an original dynamical system derived from dynamic neural fields is studied in the context of the formation of topographic maps. This dynamical system overcomes limitations of the original Self-Organizing Map (SOM) model of Kohonen. Both competition and learning are driven by dynamical systems and performed continuously in time. The equations governing competition are shown to be able to reconsider dynamically their decision through a mechanism rendering the current decision unstable, which allows to avoid the use of a global reset signal

Immunotherapy with ponezumab for probable cerebral amyloid angiopathy

Contains fulltext : 207168.pdf (publisher's version ) (Open Access)Objective: Cerebral amyloid angiopathy (CAA) is caused by cerebrovascular deposition of beta-amyloid fragments leading to cerebrovascular dysfunction and other brain injuries. This phase 2, randomized, double-blind trial in patients with probable CAA assessed the efficacy and safety of ponezumab, a novel monoclonal antibody against Abeta 1-40. Methods: Thirty-six participants aged 55-80 years with probable CAA received intravenous placebo (n = 12) or ponezumab (n = 24). The change from baseline to Days 2 and 90 in cerebrovascular reactivity (CVR) was measured in the visual cortex as the natural log of the rising slope of the BOLD fMRI response to a visual stimulus. Safety and tolerability were also assessed. Results: The mean change from baseline to Day 90 was 0.817 (ponezumab) and 0.958 (placebo): a mean ratio of 0.852 (90% CI 0.735-0.989) representing a trend towards reduced CVR in the ponezumab group. This trend was not present at Day 2. There was one asymptomatic occurrence of amyloid-related imaging abnormality-edema in the ponezumab group. The total number of new cerebral microbleeds from baseline to day 90 did not differ between groups. The ponezumab group had a participant with nonfatal new cerebral hemorrhage with aphasia and a participant with subdural hemorrhage that site investigators deemed to be nondrug related. In the placebo group one participant had a fatal intracerebral hemorrhage and one participant had migraine with aura. Interpretation: Ponezumab was safe and well-tolerated. The ponezumab group showed a trend towards treatment effect at Day 90 that was opposite to the hypothesized direction. The prespecified efficacy criteria were thus not met