Updated January 14, 2019
Research Spotlight
Eye Movements During Visuomotor Adaptation Represent Only Part of the Explicit Learning
Our eye movements are a unique window to our brain and intentions. Bromberg et al. used eye movements to assess where people aim to move their hand to. Authors show that eye movements capture only one component of the aware (explicit) aiming mechanism, and highlight probable relation between this component and mental rotation processes.
Toric Spines at a Site of Learning
Barn owls locate their prey using a precise space map of auditory/visual signals that is aligned during a developmental period of neuronal plasticity. This paper describes a new type of synaptic connection made onto the space-specific neurons that compose the map. Named 'toric' spines for their topological holes, these dendritic protrusions receive synaptic input from up to 11 axons, indicating that they act as integrators. In vivo electrophysiology, super-resolution optical microscopy and serial block electron microscopy, combined with ex vivo patch clamp recordings, support the view that toric spines are microanatomical hubs for neuronal computation, plasticity and learning.
Protein tagging is used extensively to help localising molecules of interest. Wosnitzka et al. describe a strategy allowing the localisation of BDNF, a very low abundance protein. A bicistronic mRNA marks BDNF-translating neurons in the mouse brain using GFP as surrogate nuclear marker.
Also of Interest
High-Fat Diet-Induced Obesity Causes Sex-Specific Deficits in Adult Hippocampal Neurogenesis in Mice
Poor diet and metabolic disease, including obesity and type 2 diabetes, are associated with an increased risk of neurodegenerative and neuropsychiatric disorders, including Alzheimer’s disease, anxiety, and depression. Impaired adult hippocampal neurogenesis may be one mechanism linking these conditions; however, it is unknown whether there are sex-specific effects of high-fat diet/metabolic disease on neurogenesis, which could underlie the observed sex difference in these conditions (females more adversely affected than males). We report that high-fat diet/metabolic disease impairs cell proliferation and the number of neuroblasts/immature neurons in the dorsal hippocampus, a region that supports cognitive function, in females only. Sex-specific effects of diet on microglia in the subgranular zone were also apparent.
Technology using blue wavelength light is increasingly used in neuroscience, and recent reports have noted unintended gene expression alterations during light exposure in vitro. Here, we identify light-induced gene expression alterations in rat cortical cultures, illustrate that this induction coincides with a loss of cell viability, and show that light induced gene induction is dependent on the culture media used in these experiments. We demonstrate that these unintended effects can be prevented by using phototinert media during to light exposure in vitro, opening the door for extended light exposure experiments when using powerful optical techniques in neuronal cultures.
Distribution of Midbrain Cholinergic Axons in the Thalamus
The cholinergic midbrain provides dense innervation to the thalamus and modulates its activity across different behaviors. However, the magnitude of this projection and the precise distribution of these axons in relation to different functional thalamic regions remain poorly understood. Here, we selectively labeled cholinergic axons arising in the pedunculopontine nucleus (PPN) and the laterodorsal tegmental nucleus (LDT) using conditional viral tracing. We reveal that PPN and LDT cholinergic axons are topographically organized and provide a segregated innervation of thalamic structures. PPN neurons preferentially innervate relay thalamic nuclei, whereas LDT neurons preferentially innervate thalamic limbic nuclei. Our results suggest that neurons along the functional domains of the cholinergic midbrain have a differential impact on thalamic circuits.
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