Volume 16 Issue 1, January 2013

A report elucidates the widely recognized, but poorly understood, concept of gene-environment interaction, finding a molecular mechanism in the case of post-traumatic stress disorder: demethylation of a glucocorticoid response element in the stress response regulator FKBP5 that depends on both the risk allele and childhood trauma.

In a case of sex-linked epigenetic inheritance, paternal cocaine use results in a heritable increase in cortical Bdnf gene expression that confers a cocaine-resistant phenotype in male, but not female, progeny.

Two new studies provide experimental evidence of how ancient genomic duplications of synaptic genes provided the substrate for diversification that ultimately expanded vertebrate cognitive complexity.

The ability to filter out distracting sensory information is crucial to adaptive behavior. A primate study finds that prefrontal cortex is more important than parietal cortex in that function.

The authors use patch clamp recordings and computer simulations to determine the number of molecules of glutamate released at two central synapses. They find that the amount of glutamate released maximizes the synaptic current per glutamate molecule and maximizes the signal's information content, suggesting that synapses operate under conditions that optimize resources.

GABAergic neurogliaform cells are thought to use volume transmission and provide widespread cortical inhibition, indiscriminately. To their surprise, Chittajallu et al. found that that neurogliaform cells exert a spatially restricted inhibitory influence on the mouse canonical thalamocortical circuit, as they selectively suppress feed-forward inhibition while sparing feed-forward excitation.

In this paper, the authors show that mice lacking Dlg genes each show distinct deficits in various learning paradigms. In addition, they find that humans with DLG2 mutations show similar cognitive deficits to their murine counterparts, suggesting an evolutionary conservation of function.

The authors examined the differential roles of GluN2A and GluN2B in modulating synaptic plasticity and behavior. This study provides insight into how gene duplication events during evolution can produce new functional consequences.

Gene-environment interactions of FKBP5 and early trauma predict adult stress-related psychiatric disorders. In this study, the authors reveal the molecular mechanism of how transcriptionally active variants interact with early trauma leading to long-term allele-specific changes in DNA methylation in glucocorticoid response elements of FKBP5.

In this study, the authors show that self-administration of cocaine by males resulted in an increase in BDNF expression in the mPFC and reduced drug-seeking behavior by their male offspring. This change in BDNF expression was associated with an increase in acetylated histone H3 at the Bdnf promoter IV.

The authors show that nerve injury induces expression of NRG1 type I in Schwann cells and that this expression is necessary for efficient remyelination. In addition, axonally expressed NRG1 type III can negatively regulate the expression of NRG1 type I in Schwann cells.

The authors utilize optical occlusion of penetrating blood vessels to induce cortical microinfarcts. Occlusion of even a single such vessel leads to behavioral dysfunction, whereas multiple, yet sparse, occlusions can induce substantial tissue damage. Excitotoxicity blockers ameliorate both effects.

In this study, the authors report that a focal cortical injury can induce changes in the excitability of thalamocortical neurons that contributes to the maintenance of cortical seizures. In addition, silencing these neurons via a closed-loop optogenetic approach is sufficient to interrupt these seizures.

Midbrain dopaminergic neurons show phasic elevations of firing in response to reward-predicting stimuli during learning. Here the authors provide data from in vivo recordings and optogenetic stimulation to support a role for monosynaptic inhibition of dopamine neurons from projection neurons in the substantia nigra in extinction of learned behaviors.

By pairing acoustic stimuli and electrical stimulation of the nucleus basalis neuromodulatory system in rats, the authors show an induction of long-lasting synaptic modifications of the auditory cortex that conserved excitation across the auditory receptive fields. This type of modification also improved auditory sensory detection and behavioral performance in tone perception.

Functional links between neuronal activity and perception are studied by examining trial-by-trial correlations (choice probabilities) between neural responses and perceptual decisions. Here the authors report that subcortical vestibular neurons show robust choice probabilities if they selectively represent self-translation, suggesting that choice-related activity emerges from a critical transformation of vestibular signals.

Here the authors show that the suppression of salient, but task-irrelevant, distractors is much stronger in the dorsolateral prefrontal cortex (dlPFC) than in the lateral intraparietal area (LIP). Their results suggest that, although both areas can contribute to perceptual selection, the dlPFC has a decisive influence on whether a salient stimulus influences actions.

This study examines the neural coding of decision confidence when human subjects make value-based economic choices, and finds that signals of explicit confidence are encoded in the activity of ventromedial prefrontal cortex and its interaction with the rostrolateral prefrontal cortex.