Articles in 2017

A long-standing idea in modern neuroscience is that the brain computes inferences about the outside world rather than passively observing its environment. The authors record from midbrain dopamine neurons during tasks with different reward contingencies and show that responses are consistent with a learning rule that harnesses hidden-state inference.

Shi et al. performed a systematic clonal analysis and revealed an intricate ontogenetic logic of structural development and functional organization of the mammalian thalamus. Notably, neurons in cognitive versus sensory or motor nuclei as well as in first-order versus high-order sensory or motor nuclei across different modalities exhibit distinct progenitor origin and spatial configuration.

How hippocampal place cells participate in fear memory retrieval is unknown. Wu et al. show that, when rats retrieve prior shock experience prompting them to avoid a shock zone, precise place cell activity patterns encoding paths from animals’ current locations to the shock zone are replayed in association with high-frequency ripple oscillations.

Using single-neuron recordings in the human brain during a working-memory task, the authors show both stimulus-specific and nonspecific types of persistent activity in neurons of the medial frontal and medial temporal lobes. Persistent activity in hippocampus and amygdala was predictive of memory content and displayed dynamic attractor patterns.

The authors show that activation of GluK2-containing kainate receptors on hippocampal neurons, by either agonist application or high-frequency synaptic stimulation, leads to a new form of NMDA-receptor-independent LTP. Induction of this form of plasticity requires the metabotropic action of postsynaptic kainate receptors, which triggers spine growth and potentiation of AMPA-receptor-mediated transmission.

The authors use a variety of techniques to isolate and manipulate retinal inputs to direction-selective neurons in the mouse superior colliculus. They show that these cells inherit their selectivity from the retina by combining inputs from similarly tuned ganglion cells, which are further amplified in the colliculus without altering selectivity.

Drugs of abuse alter the strength of synaptic connections within the mesocorticolimbic dopamine system. The current study demonstrates that this is dependent on the recruitment of cadherin to the synaptic membrane. Increased cadherin at dopaminergic synapses impairs cocaine-induced synaptic plasticity, resulting in a reduction in cocaine preference.

The nature of astrocyte diversity in the adult brain has remained poorly defined. The authors identify five astrocyte subpopulations in the brain that exhibit extensive molecular and functional diversity. They uncover correlative populations in malignant glioma, providing insight into how diverse astrocyte populations contribute to synaptogenesis, tumor pathophysiology and neurological disease.

Social behaviors require neural circuits to process social cues and orchestrate motivational states. This study identifies a subpopulation of hypothalamic neurons expressing neurotensin that are engaged by social and hormonal signals. These neurons project to midbrain dopaminergic reward systems to promote and reinforce social and motivated behavior in a hormone-sensitive manner.

The role of pericytes in the regulation of cerebral blood flow (CBF) and neurovascular coupling remains unclear. Using loss-of-function pericyte-deficient mice, the authors report that pericyte degeneration reduces CBF responses to neuronal stimuli and oxygen supply to the brain, leading to metabolic stress, neuronal dysfunction and neurodegeneration.

Using magnetic resonance spectroscopy, Shibata et al. show that continuous training conducted after performance improvement has been maximized hyperstabilizes the skill learned and protects it from subsequent new learning by drastically changing early visual areas from excitatory (glutamate)-dominant to inhibitory (GABA)-dominant neurochemical environments.

Effective social behavior requires comprehension of social cues and use of those cues to guide behavior. This study uncovers an amygdala circuit that is necessary for socially driven valuation of environmental cues. The strength of this circuit correlates with social learning, and augmentation of this circuit enhances abnormal social learning.

Inputs to midbrain dopamine neurons control rewarding and drug-related behaviors. The authors found that nucleus accumbens inputs and local GABA neurons inhibit dopamine neurons through distinct populations of GABA receptors. Furthermore, genetic deletion of GABA_B receptors from dopamine neurons selectively increased behavioral sensitivity to cocaine.

The authors investigate the role of inhibition in shaping spatial selectivity of CA1 place cells. Combining whole-cell recordings, optogenetics and computational modeling, they demonstrate that inhibition enhances both rate and temporal coding of space by counteracting noise from broad out-of-field excitation.

The function of rapid eye movement (REM) sleep remains unclear. By examining how REM sleep affects synapses in the mouse cortex, the authors show that REM sleep is fundamental to brain development, learning and memory consolidation by selectively pruning and maintaining newly formed synapses via dendritic calcium spike-dependent mechanisms.

Vision is processed across multiple cortical areas that are organized into two subnetworks in primates. However, the generality of this organization and its development are unclear. Smith and colleagues present functional evidence for the analogous two subnetworks in mice and map their differential developmental dynamics.

The authors describe cortical projections mediating the modulation of social behavior. Neural projections from the medial prefrontal cortex to the dorsal periaqueductal gray play a critical role in the behavioral adaptation to social defeat in mice.

Episodic memory involves encoding an event's temporal and spatial context. The authors show that temporal information is mediated by a direct projection from the dorsal CA1 field of the hippocampus to the medial prefrontal cortex, while spatial information is processed in a separate hippocampal–prefrontal cortex projection originating in intermediate CA1.

The authors show that postsynaptic deletion of neuroligin-3 from parvalbumin interneurons causes a decrease in NMDA-receptor-mediated excitatory postsynaptic currents and an increase in presynaptic glutamate release probability linked to a deficit in presynaptic Group III metabotropic glutamate receptor function. This selective disruption of excitatory transmission on parvalbumin interneurons leads to abnormal hippocampal network activity and a decrease in contextual fear extinction.