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Volume 12 Issue 1, January 2009

Retinitis pigmentosa is characterized by an initial loss of rod photoreceptors followed by a progressive loss of cones, although the known mutations causing retinitis pigmentosa are all in rod-specific genes. Punzo et al. now report that rod-specific mutations in the insulin/mTOR pathway may contribute to cone death as a result of photoreceptor starvation. The cover depicts phosphorylated mTOR in dorsal cone receptors (cell bodies in magenta, outer segments in green and mTOR in red).

(pp 5 and 44)

Editorial

  • Scientific publishing depends on expert peer reviewers. Instead of perpetually arguing about the reliability and fairness of peer review, authors, editors and referees should seek to optimize this time-tested system.

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Book Review

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News & Views

  • In retinitis pigmentosa, rod and cone photoreceptors die. Although rods die as a consequence of rod-specific genetic mutations, there is no clear explanation for the progressive loss of cones. A new study in this issue suggests that changes in the insulin/mTOR pathway and cell starvation can partially account for cone death in this disease.

    • Paola Bovolenta
    • Elsa Cisneros
    News & Views
  • When prion proteins go wrong, they can do serious damage, but little is known about their normal function, despite their ubiquitous expression in the brain. A new report in this issue suggests a critical role for prions in olfactory discrimination.

    • Donald A Wilson
    • Ralph A Nixon
    News & Views
  • Neurofibromatosis type I is often associated with learning disabilities. Recent work shows that lack of neurofibromin impairs memory because overactive ERK signaling in hippocampal interneurons causes excessive GABA release.

    • Kevin J Staley
    • Anne E Anderson
    News & Views
  • Cortical and thalamic contribution to V1 neuron response properties is thought to be fixed. New work overturns this assumption, showing that the spread of corticocortical activation can be strongly modulated by stimulus strength.

    • Harvey A Swadlow
    • Jose-Manuel Alonso
    News & Views
  • Research indicates that sleep influences learning, but little is known about the mechanisms involved. A recent article suggests that sleep modifies the firing patterns of sensorimotor neurons before there is improvement in performance.

    • Todd W Troyer
    • Christopher M Glaze
    News & Views
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Review Article

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Brief Communication

  • Activation of GABAA 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.

    • Lindsey L Glickfeld
    • J David Roberts
    • Massimo Scanziani
    Brief Communication
  • 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.

    • Weiwei Zhang
    • Steven J Luck
    Brief Communication
  • 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.

    • Xiaoming Zhou
    • Michael M Merzenich
    Brief Communication
  • 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.

    • Michael X Cohen
    • Jan-Christoph Schoene-Bake
    • Bernd Weber
    Brief Communication
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Article

  • 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.

    • Rachel M Huckfeldt
    • Timm Schubert
    • Rachel O L Wong
    Article
  • 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.

    • Claudio Punzo
    • Karl Kornacker
    • Constance L Cepko
    Article
  • The normal physiological function of the prion protein PrPC 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 PrPC.

    • Claire E Le Pichon
    • Matthew T Valley
    • Stuart Firestein
    Article
  • 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.

    • Ian Nauhaus
    • Laura Busse
    • Dario L Ringach
    Article
  • 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.

    • Masayuki Matsumoto
    • Okihide Hikosaka
    Article
  • 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.

    • Yosuke Morishima
    • Rei Akaishi
    • Katsuyuki Sakai
    Article
  • 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.

    • Sonia J Bishop
    Article
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