Brief Communications in 2013

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.

How the cortex processes and transforms sensory input coming from the thalamus is still a matter of debate. Here the authors optogenetically silence local cortical circuits to show that intracortical excitation amplifies and prolongs thalamic inputs to the auditory cortex.

Grid cell activity in the rodent and non-human primate entorhinal cortex is thought to provide spatial location information to the hippocampus for navigation and spatial processing. Here, Jacobs et al. examined single neuron spiking activities from human subjects performing a virtual spatial navigation task and show the presence of grid-like firing activity.

The authors use two-photon Ca²⁺ imaging of axonal boutons in hippocampal CA1 of behaving mice to monitor the activation of septo-hippocampal GABAergic boutons. They report that some sensory inputs are more effective than locomotion in driving firing by these long-range GABAergic projections.

Although oxytocin is generally thought to exert anxiolytic, prosocial and antistress effects, reports of anxiogenic effects in humans have recently emerged. Here the authors show that oxytocin receptors in the lateral septum mediate the stress-induced enhancement of fear conditioning in mice in a process involving MAPK-ERK signaling.

It's unclear how the brain alters sensory processing in response to emotionally laden stimuli. Here the authors show that changes in auditory acuity depend on the auditory cortex and on how specific a cue is in predicting an aversive stimulus.

The authors report that, when subjects are asked to remember visual properties of an object, object identity can be decoded from fMRI measures of activity in extrastriate, but not prefrontal, cortex, whereas the opposite holds when they are asked to remember nonvisual properties. Thus, the ability to maintain information during working memory is a general and flexible cortical property.

In this study, the authors show that information regarding both the identity and the value of a given odor is multiplexed in the anterior piriform cortex. Specifically, they find that value is encoded by changes in firing rate while identity is determined by sniff-locked spiking.