Articles

microRNAs control synaptic signaling through regulation of postsynaptic responsiveness. This study provides evidence that the conserved microRNAs miR-1000 and miR-137 act presynaptically via glutamate transporters to regulate glutamate release. miR-1000 expression is activity dependent, perhaps allowing activity to fine-tune the strength of excitatory synaptic transmission.

The authors recorded spiking activity in the sensorimotor striatum of rats performing a motor sequence in an automatic manner. They report continuous and integrative representation of contextual and kinematic information. Reversible perturbation of these representation increased execution variability, suggesting a strong contribution in constraining the execution motor habits.

The authors show that astrocytes produce high levels of the adenosine receptor A2A in Alzheimer brains. Reducing the levels of astrocytic A2A boosted memory in young and aging mice and mouse models of Alzheimer disease, whereas activating a related molecular pathway impaired memory. Thus, astrocytes regulate memory and abnormal receptor activity in these cells may contribute to memory disorders.

Combining single-neuron recordings and a multistep economic choice task in monkeys, the authors find activity in amygdala neurons that predicts the value and length of an internally planned choice sequence leading to future reward. Prospective amygdala activity appears to encode components of an internal plan and guide behavior over several steps towards self-defined, distant goals.

Enhanced NMDA receptor function and social interaction deficits are observed in mice lacking the excitatory postsynaptic scaffolding protein IRSp53. Reducing NMDAR activity by pharmacological methods rescues the impaired social interaction observed in these mice. This suggests that enhanced NMDA receptor function may be associated with social deficits.

The authors find that behavioral habituation to the repeated presentation of visual stimuli, measured as reduced occurrence of a brief motor response called a 'vidget', depends on primary visual cortex in mice and is accompanied by a potentiation of layer 4 responses to visual stimuli. Local manipulations indicate that this form of recognition memory is stored in primary visual cortex.

Better analytical methods are needed to extract biological meaning from genome-wide association studies (GWAS) of psychiatric disorders. Here the authors take GWAS data from over 60,000 subjects, including patients with schizophrenia, bipolar disorder and major depression, and identify common etiological pathways shared amongst them.

Rapid developmental changes in the response properties of neurons in visual cortex enhance motion discriminability following eye opening. Here the authors show that increases in direction selectivity are accompanied by reductions in the density of active neurons and variability in their responses and levels of noise correlation, changes that depend on the nature of visual experience.

Previous studies have reported both increased and decreased functional brain connectivity in individuals with autism spectrum disorder (ASD). The authors find that instances of such over- and underconnectivity in adults with high-functioning ASD point to a deeper principle of increased individual variation (idiosyncrasy) of functional connectivity in individuals with ASD.

Donahue and Lee identify prefrontal neurons that integrate task-relevant information about past and current stimulus features and past action outcomes across trials during a probabilistic reversal task. The activity of these neurons is sensitive to past rewards and is predictive of imminent behavioral choices, suggesting that they dynamically contribute to the selection of actions that maximize reward during decision making under uncertainty.

The authors find that glutamate release increases the diffusion of the astrocytic glutamate transporter GLT-1 in the plasma membrane. This activity-dependent increase in mobility facilitates glutamate clearance from the synaptic cleft, which influences the kinetics of excitatory post-synaptic events in rat hippocampal neurons.

Due to their volatility, olfactory inputs are spatially and temporally dynamic. Here the authors find that, in contrast to previous studies, mitral/tufted cells of the olfactory bulb can sum inputs linearly across odors and time.

The authors report that neddylation is required for dendritic spine development and stability, and loss of neddylation in excitatory forebrain neurons leads to synaptic loss, impaired neurotransmission, and learning and memory deficits. The roles of neddylation in spine maturation and synaptic transmission could be attributed to neddylation of PSD-95.

In amyotrophic lateral sclerosis (ALS), some motor neuron types are more vulnerable to disease pathology. Here the authors show that resistant subtypes express the ER chaperone SIL1. Disease-associated loss of SIL1 impairs ER homeostasis and worsens ALS pathology, whereas its expression improves pathology and survival in an ALS mouse model.

During a single theta cycle, discrete groups of hippocampal place cells can produce a distributed series of spikes called a theta sequence. Such sequences represent the time-compressed trajectory of an animal running in its environment and usually extend ahead of the current position. Here, Wikenheiser and Redish find that the ‘look-ahead’ distance of rat theta sequences can predict the imminent choice of the animal in a value-guided decision making task.

Autism spectrum disorders (ASDs) are characterized by both phenotypic and genetic heterogeneity. Here the authors find that ASD functional genetic networks are enriched for genes expressed in deep layer cortical neurons, that mutations in females impact more highly expressed genes as compared to males and that intellectual scores reflect the severity of mutations.

Wang and colleagues find that weakening hippocampal theta in a familiar environment reduces the performance of rats in a spatial memory task, decreases the number of theta sequences and degrades internally generated hippocampal episode cell firing, while leaving place cell firing intact. The same weakening of theta also prevents the formation of a precise spatial representation in a novel environment unless proximal cues are present. Together these results suggest that the mechanisms underlying internally generated hippocampal sequences of activity are crucial for episodic memory.

Here, the authors imaged calcium response in the mouse olfactory bulb in vivo to show that the calcium transients in astrocytic processes—but not cell bodies—are tightly coupled to neuronal activity and precede functional hyperemia.

Drosophila optic lobe neurons are generated from the outer and inner proliferation centers (IPC). The authors show a new mode of neurogenesis in which progenitors in one IPC domain migrate to a second domain where they mature into neural stem cells/neuroblasts. They also identify several genes that regulate this process.

The authors show that mice lacking the gene Erbb4 in somatostatin-expressing (SOM) neurons of the thalamic reticular nucleus (TRN) show selective behavioral deficits in tasks involving switching attention between cues of different sensory modalities. Slice recordings also showed enhanced cortical drive in Erbb4-deficient TRN SOM neurons.