Author Correction: Increasing neurogenesis refines hippocampal activity rejuvenating navigational learning strategies and contextual memory throughout life.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Increasing neurogenesis refines hippocampal activity rejuvenating navigational learning strategies and contextual memory throughout life.

Functional plasticity of the brain decreases during ageing causing marked deficits in contextual learning, allocentric navigation and episodic memory. Adult neurogenesis is a prime example of hippocampal plasticity promoting the contextualisation of information and dramatically decreases during ageing. We found that a genetically-driven expansion of neural stem cells by overexpression of the cell cycle regulators Cdk4/cyclinD1 compensated the age-related decline in neurogenesis. This triggered an overall inhibitory effect on the trisynaptic hippocampal circuit resulting in a changed profile of CA1 sharp-wave ripples known to underlie memory consolidation. Most importantly, increased neurogenesis rescued the age-related switch from hippocampal to striatal learning strategies by rescuing allocentric navigation and contextual memory. Our study demonstrates that critical aspects of hippocampal function can be reversed in old age, or compensated throughout life, by exploiting the brain's endogenous reserve of neural stem cells.

Pavlovian Conditioning of Larval Drosophila: An Illustrated, Multilingual, Hands-On Manual for Odor-Taste Associative Learning in Maggots.

Larval Drosophila offer a study case for behavioral neurogenetics that is simple enough to be experimentally tractable, yet complex enough to be worth the effort. We provide a detailed, hands-on manual for Pavlovian odor-reward learning in these animals. Given the versatility of Drosophila for genetic analyses, combined with the evolutionarily shared genetic heritage with humans, the paradigm has utility not only in behavioral neurogenetics and experimental psychology, but for translational biomedicine as well. Together with the upcoming total synaptic connectome of the Drosophila nervous system and the possibilities of single-cell-specific transgene expression, it offers enticing opportunities for research. Indeed, the paradigm has already been adopted by a number of labs and is robust enough to be used for teaching in classroom settings. This has given rise to a demand for a detailed, hands-on manual directed at newcomers and/or at laboratory novices, and this is what we here provide. The paradigm and the present manual have a unique set of features: The paradigm is cheap, easy, and robust;The manual is detailed enough for newcomers or laboratory novices;It briefly covers the essential scientific context;It includes sheets for scoring, data analysis, and display;It is multilingual: in addition to an English version we provide German, French, Japanese, Spanish and Italian language versions as well.The present manual can thus foster science education at an earlier age and enable research by a broader community than has been the case to date.

Measurement, modeling, and prediction of temperature rise due to optogenetic brain stimulation.

Optogenetics is one of the most important techniques in neurophysiology, with potential clinical applications. However, the strong light needed may cause harmful temperature rises. So far, there are no methods to reliably estimate brain heating and safe limits in actual optogenetic experiments. We used thermal imaging to directly measure such temperature rises at the surface of live mouse brains during laser illumination with wavelengths and intensities typical for optogenetics. We then modeled the temperature rise with a simple logarithmic model. Our results indicate that previous finite-element models can underestimate temperature increases by an order of magnitude. We validate our empirical model by predicting the temperature rise caused by pulsed stimulation paradigms. These predictions fit closely to the empirical data and constitute a better estimate of real temperature increases. Additionally, we provide a web-based app for easy calculation that can be used as a tool for safe design of optogenetic experiments.