Articles in 2008

This study combines transcranial magnetic stimulation (TMS) and electroencephalography (EEG) and finds that TMS over frontal eye fields affects EEG over more posterior areas. This effect was modulated by the task and attentional preparation and provides causal evidence for the existence of a prefrontal top-down control signal.

The normal physiological function of the prion protein PrP^C remains unknown. Here, the authors report that PrP knockout mice show altered behavior in two olfactory tasks and that PrP deficiency affects oscillatory activity in the olfactory bulb. Both the behavioral and electrophysiological phenotypes could be rescued by transgenic neuronal-specific expression of PrP^C.

Neuronal response selectivity and perceptual discrimination can be affected by acoustic experience during development. Here the authors show that intensive discrimination training in adult animals can restore normal cortical response patterns.

Previous work links hyper-responsive threat detection to anxiety. Using fMRI, this study finds that highly anxious individuals had reduced prefrontal cortex activity and slower target identification during a response conflict task when the task did not fully use up their attentional resources. Trait anxiety is therefore linked to less prefrontal attentional control, even when there are no threatening stimuli.

Transgenic expression of microbial channelrhodopsins in neurons allows direct light activation of ionic currents. Here, the authors describe a modified channelrhodopsin that remains open for seconds once it is activated by light and can be 'switched off' by a second light flash, thereby obviating the need for constant illumination during an experiment.

The retinal degeneration disease retinitis pigmentosa is characterized by an initial loss of rod photoreceptors followed by a progressive loss of cones. Providing a mechanism behind the long delay of cone death in retinitis pigmentosa, Punzo et al. identify and characterize the involvement of an insulin/mTOR pathway, indicating that cell starvation of cones can partially account for the nonautonomous photoreceptor death in retinitis pigmentosa.

Tiling describes the arrangement of neuronal processes in a pattern with little or no overlap with those of neighboring neurons. It is unclear how this is mediated in the vertebrate retina, whose mosaic cell body distribution of horizontal cells is accompanied by extensively overlapping dendrites. A study by Huckfeldt et al. now shows that the nonrandom distribution of the horizontal cells is correlated with repulsive homotypic interactions between developmentally transient processes, leading to the development of initial territories of horizontal cell.

On the heels of a new law, scientists in Italy are facing precarious times yet again.

Glial cells that express NG2 and platelet-derived growth factor receptor α are found throughout the mature CNS. These cells are mitotically active, but their functions remain enigmatic. A genetic fate-mapping study in this issue shows that these abundant glial cells can generate both oligodendrocytes and some cortical projection neurons in the adult brain.

A study in this issue shows that zebrafish larvae deploy different groups of excitatory spinal interneurons to drive slow, fast and top speed swimming. As one set is gradually activated, the others are partially or fully inhibited.

Correlations in firing rate between pairs of neurons can change depending on task and attentional demands. This new finding suggests that measuring correlations can help to reveal how neural circuits process information.

Demonstrating how specific motor signals modulate sensory processing in the rat vibrissal system, a new study in this issue shows that motor signals first attenuate and then amplify afferent sensory signals.

The authors report that the population of lateral habenula neurons responds most strongly for the most unpleasant outcome in a particular context: either the absence of reward when rewards are available or the presence of punishment when punishments are feared.

Liu and Davis identify a GABAergic neuron, the anterior paired lateral neuron, that innervates the mushroom body neuropil and elaborate on the reciprocal relationship between GABA signaling and Drosophila olfactory memory.

Attention is thought to select nonspatial features later than spatial location. This study uses ERPs to show that color-based attention effects manifest themselves as early as 100 ms, similar to spatial attention effects.

Prosopagnosics have impaired face recognition, but make relatively normal responses to face stimuli in core brain regions for face recognition. The authors now report that it is the connectivity among these regions that is being disrupted in the disorder.