Brief Communications

In this study, the authors use measures of carbon-14 in neuronal DNA from human stroke patient cortical tissue samples to show that, unlike previous studies done in rodents, they do not find any evidence of increased neurogenesis after an ischemic injury. In addition, DNA damage assays suggest that there is no increase in DNA rearrangement after this insult.

In this paper, Clancy and colleagues introduce an optically driven brain machine interface (BMI) based on the processing of optical calcium signals recorded using two-photon microscopy. When applied to mouse cortex, this approach revealed that learning in a BMI-mediated operant task is accompanied by the progressive spatial refinement of activity in local networks comprising output-relevant neurons.

In this study, the authors show that the heritable behavioral and metabolic changes that are observed in rodents exposed to early life stress are mediated by changes in miRNA levels in the sperm of affected males. Injection of isolated RNA from the sperm of stressed males into donor fertilized oocytes is able to induce these phenotypic changes in the resulting offspring.

Many mouse models of Alzheimer's disease (AD) rely on overexpression of amyloid precursor (APP) transgenes, which makes it difficult to tease out which effects are truly disease-relevant and which are induced by the overexpression. In this study, the authors describe several new knock-in AD model mice that express mutant APP at near physiological levels.

The authors identify mutations in the MATR3 gene as a cause of ALS and dementia in several families. MATR3 is known to bind the ALS-associated protein TDP-43, and at least one of these mutations alters the efficiency of this binding.

The authors show that sharp-wave events recorded in mouse hippocampal slices are more likely to involve neurons that have been activated during a recent behavioral episode. The excitation/inhibition balance of the synaptic inputs received by these cells during sharp waves is biased toward excitation, suggesting a potential mechanism for their preferential recruitment into these network events.

In this study, the authors examine the effects of caffeine on long-term memory. They find that a specific caffeine dose administered shortly after participants studied images improves image-recognition performance a day later. This suggests that caffeine may enhance memory consolidation separately from other cognition-enhancing effects.

The reconsolidation hypothesis states that reactivated memory traces are vulnerable to disruption from treatments that also impair initial memory consolidation. In this study, the authors demonstrate that electroconvulsive therapy—an invasive procedure—disrupts reactivated episodic memories when tested 1 d later, but not when tested shortly after treatment.

Chronic social-defeat stress increases phasic firing of ventral tegmental area (VTA) neurons and increases the amount of BDNF in the nucleus accumbens (NAc). The authors show that increased activity of NAc-projecting VTA neurons is sufficient to increase the amount of BDNF in the NAc, an effect that depends on CRF signaling in the NAc.

The authors find that pharmacological inactivation of the lateral habenula leaves rats indifferent when choosing between rewards associated with different costs and benefits. These data show that the lateral habenula not only signals aversion but also functions as a preference center to promote subjective decision biases during goal-directed behavior.

Transplanted neurons often fail to migrate sufficiently into host brain tissue. In this study, the authors show that this migration deficiency may not be the result of a nonpermissive host environment but instead is due to a chemoattractive effect of grafted neural precursors on their own neuronal progeny.

Here the authors used optogenetic stimulation to trigger antidromic spikes in a local region of primary visual cortex. This local activity caused two effects at distal locations: summation and division. The balance between the two depended on visual contrast, and a normalization model captured these effects.

This study shows that neural progenitor cells in the adult hippocampus of mice receive immature GABAergic synaptic inputs from parvalbumin (PV)-expressing interneurons, and uses optogenetic stimulation to demonstrate local PV interneuron activation via GABA signaling promotes survival and maturation of newborn neurons.

In this paper the authors demonstrate that functionally independent populations of neurons in the ventromedial hypothalamus (VMH), a region implicated in feeding, sex, and aggression, are essential for predator and social fear in mice.

In this study, the authors show that the mouse ortholog of the amyotropic lateral sclerosis/frontotemporal dementia (ALS/FTD)-associated human locus C9ORF72 exhibits highly enriched expression in the neuronal cell types that show susceptibility during the disease. These findings suggest a potential explanation for the cell selectivity observed in ALS/FTD.

Here the authors show that optogenetic stimulation of Purkinje cells, the sole output neurons of the cerebellar cortex, can drive motor learning in mice. This represents an additional instructive signal for the induction of learning, beyond climbing fibers, that can expand the learning capacity of motor circuits.

It has been suggested that posterior insular regions code lower-level sensory information and anterior regions code higher-level stimulus significance relative to the body's homeostatic needs. However, here the authors report that the caudal, but not rostral, insula response to food images was directly related to the body's homeostatic state.

Sleep has been shown to strengthen various types of memory, including emotional memory. Here the authors show that in subjects who have learned to associate an odor with an electric shock, re-exposure to the odor during slow-wave sleep promotes extinction of the memory for the odor-shock association.

The authors find that white matter–derived OPCs differentiate with similar efficiencies whether they are engrafted into white matter or gray matter, while gray matter–derived OPCs only differentiate with high efficiency when placed in white matter. This suggests that there are intrinsic differences between OPCs depending on their site of origin.

Using in vivo imaging of layer V pyramidal neurons in the dorsomedial frontal cortex of mice, the authors show that cocaine administration rapidly increases the formation and accumulation of dendritic spines. These spine changes correlate with conditioned place preference for cocaine, but not with cocaine-induced locomotor activity.