Articles in 2008

The striatum receives projections to a number of cortical and subcortical areas. The authors report here that fiber tracts from prefrontal cortex are correlated with individual differences in reward dependence and that tracts from the hippocampus, amygdala and ventral striatum are correlated with individual differences in novelty seeking.

This review discusses new work that explores how Eph/ephrin forward and reverse signaling affect spine maturation, synaptogenesis and synaptic long-term potentiation.

Activation of GABA_A receptors can depolarize specific neuronal compartments, causing excitation. The authors report that hippocampal interneurons hyperpolarize pyramidal cells, irrespective of the location of their synapses, along the entire somato-dendritic axis.

By simultaneously recording spikes and local field potentials (LFPs) in cat and monkey visual cortex, the authors demonstrate that the magnitude and spread of LFP waves from the originating spike are reduced with increasing stimulus contrast. This suggests that visual cortex functional connectivity is not fixed, but is instead modulated by stimulus contrast.

In sedated and whisking rats, the authors show that motor cortex activity enhances sensory processing through a cortico-cortico-thalamic feedback circuit. In whisking rats, however, inhibitory brainstem input to the thalamus was also enhanced, leading to a net suppression of thalamic sensory responses.

The nervous system produces accurate movements by adapting to environmental changes. The authors construct a probabilistic model that compensates for motor errors and estimates their sources, finding that if the motor system used such a strategy, it would explain many previously observed movement-generalization phenomena.

It has been proposed that neurons in the intraparietal cortex gradually accumulate evidence supporting different response options. Here the authors show that this model generalizes to arbitrary stimulus-response associations in humans.

The authors here show that two completely different classes of spinal premotor interneurons drive motoneurons during slow and fast swimming of zebrafish larvae. As the fish accelerate, the 'slow' interneurons are progressively silenced, while the 'fast' interneurons take over, and vice versa.

Genetic ablation of β-catenin in the embryonic ventral forebrain restricted proliferation of neural precursors in the medial ganglionic eminence, resulting in fewer cholinergic projection neurons in basal forebrain and fewer calbindin- and somatostatin-positive interneurons in the cortex. This work suggests a crucial role for canonical Wnt signaling in ventral forebrain neurogenesis.

No two roses smell exactly alike, but our brain accurately bundles these variations into a single percept 'rose'. The authors now report that although olfactory bulb neurons decorrelate odor mixtures that are quite similar, piriform cortex neuronal responses show pattern completion and predict olfactory perception.

fMRI studies suggest that nucleus accumbens (NAc) activation increases in response to stimuli of different hedonic valence, whereas physiological evidence suggests that NAc neurons show increases in activity for rewarding stimuli and pauses for aversive stimuli. Using cyclic voltammetry, the authors find that patterns of dopamine release and metabolic activity differentiate between rewarding and aversive stimuli.

Dopamine is known to contribute to the amygdala-mediated aversive response, where increased dopamine release can augment amygdala function. Combining fMRI and PET imaging techniques, Kienast et al. present findings that suggest a functional link between anxiety temperament, dopamine storage capacity and emotional processing in the amygdala.

The authors report that fMRI responses in human foveal retinotopic cortex contain information about objects presented in the periphery. This information is position invariant and correlated with perceptual discrimination accuracy.

Lie-detection tests have not been scientifically proven to reliably detect deception at an individual level, yet they are being marketed by several companies and have even been admitted as evidence in an Indian court. This calls for a critical appraisal of these technologies and regulatory measures to prevent misuse.

Oldham et al. present a systematic analysis of gene coexpression relationships in specific human brain regions with the goal of identifying groups of genes with common coexpression patterns. The study used the inherent structure of the brain's transcriptome to find data-driven organizational patterns rather than rely on external classification systems.

A paper in this issue reports that the core mechanisms that strengthen memories have more in common with the mechanisms that support reconsolidation than those that participate in their initial storage.

A recent paper reported the in vitro generation of new prion strains, supporting the idea that 'strain-ness' is encoded in the protein structure itself. This lays the groundwork for a reinvigorated study of prion structure–pathology relationships.