Published by Elsevier Inc.”
“One obstacle to understanding the exact processes unfolding inside the hippocampus is that it is still difficult to clearly define what the hippocampus actually does, at the system level. Associated for a long time with the formation of episodic and semantic memories, and with their temporary storage, the hippocampus is also regarded as a structure involved in spatial

navigation. These two independent perspectives DMH1 ic50 on the hippocampus are not necessarily exclusive: proposals have been put forward to make them fit into the same conceptual frame.\n\nWe review both approaches and argue that three critical developments need consideration: (a) recordings of neuronal activity in rodents, revealing beautiful spatial codes expressed in entorhinal cortex, upstream of the hippocampus; (b) comparative behavioral results suggesting, in an evolutionary perspective, qualitative similarity of function across homologous structures with a distinct internal organization; (c) quantitative measures of information, shifting

the focus from who does what to how much each neuronal population expresses each code.\n\nThese developments take the hippocampus away from philosophical discussions of all-or-none cause-effect relations, and into the quantitative mainstream of modern neural science. (C) 2011 Elsevier Ltd. All rights reserved.”
“The initial structural and functional development of visual circuits in reptiles, birds, and mammals happens independent of sensory experience. this website After eye opening, visual experience further refines and elaborates circuits that are critical for normal visual function. Innate genetic programs that code for gradients of molecules provide gross positional information for developing nerve cells, yet much of the cytoarchitectural complexity and synaptogenesis of neurons depends on calcium influx, neurotransmitter release, and neural activity before the onset of vision. In fact, specific spatiotemporal patterns

of neural activity, or ‘retinal waves’, emerge amidst the development of the earliest connections made between excitable cells in the developing eye. AZD4547 cell line These patterns of spontaneous activity, which have been observed in all amniote retinae examined to date, may be an evolved adaptation for species with long gestational periods before the onset of functional vision, imparting an informational robustness and redundancy to guide development of visual maps across the nervous system. Recent experiments indicate that retinal waves play a crucial role in the development of interconnections between different parts of the visual system, suggesting that these spontaneous patterns serve as a template-matching mechanism to prepare higher-order visually associative circuits for the onset of visuomotor learning and behavior.