Hot off the presses! Dec 10 Neuron

The Dec 10 issue of the Neuron is now up on Pubget (About Neuron): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

• Taking Off the SOCS: Cytokine Signaling Spurs Regeneration
  - Neuron 64(5):591-592 (2009)
  Strategies to improve function after CNS injuries must contend with the failure of axons to regrow after transection in adult mammals. In this issue of Neuron, Smith et al. provide an important advance by demonstrating that SOCS3 acts as a key negative regulator of adult optic nerve regeneration.
• A New Class of Spinal Interneurons: The Origin and Function of C Boutons Is Solved
  - Neuron 64(5):593-595 (2009)
  C boutons, a major synaptic input to motor neurons, were first described years ago, but their origin and functional significance were unknown. In this issue of Neuron, a group of cholinergic interneurons located near the central canal is identified as the source of C boutons. The rhythmic activity in these neurons during locomotion increases motor neuronal excitability, thereby potentiating the strength of muscle contraction.
• Rab3 GTPase Lands Bruchpilot
  - Neuron 64(5):595-597 (2009)
  Active zones are the sites of neurotransmitter release, but their assembly mechanisms are poorly understood. In this issue of Neuron, Graf et al. perform a genetic screen in Drosophila and uncover a novel role for the Rab3 GTPase in organizing the active zone at the neuromuscular junction.
• Fields of Gain in the Brain
  - Neuron 64(5):598-600 (2009)
  For more than two decades, neuroscientists have debated the role of "gain fields" in sensorimotor transformations. In this issue of Neuron, Chang et al. demonstrate a tight correlation between eye and hand position gain fields in the "parietal reach region," strongly suggesting that they play a functional role in computing the reach command.
• Robert J. Wenthold (1948–2009)
  - Neuron 64(5):603-604 (2009)
  
• The Challenges Natural Images Pose for Visual Adaptation
  - Neuron 64(5):605-616 (2009)
  Advances in our understanding of natural image statistics and of gain control within the retinal circuitry are leading to new insights into the classic problem of retinal light adaptation. Here we review what we know about how rapid adaptation occurs during active exploration of the visual scene. Adaptational mechanisms must balance the competing demands of adapting quickly, locally, and reliably, and this balance must be maintained as lighting conditions change. Multiple adaptational mechanisms in different locations within the retina act in concert to accomplish this task, with lighting conditions dictating which mechanisms dominate.
• Frequency Transitions in Odor-Evoked Neural Oscillations
  - Neuron 64(5):692-706 (2009)
  In many species, sensory stimuli elicit the oscillatory synchronization of groups of neurons. What determines the properties of these oscillations? In the olfactory system of the moth, we found that odors elicited oscillatory synchronization through a neural mechanism like that described in locust and Drosophila. During responses to long odor pulses, oscillations suddenly slowed as net olfactory receptor neuron (ORN) output decreased; thus, stimulus intensity appeared to determine oscillation frequency. However, changing the concentration of the odor had little effect upon oscillatory frequency. Our recordings in vivo and computational models based on these results suggested that the main effect of increasing odor concentration was to recruit additional, less well-tuned ORNs whose firing rates were tightly constrained by adaptation and saturation. Thus, in the periphery, concentration is encoded mainly by the size of the responsive ORN population, and oscillation frequ! ency is set by the adaptation and saturation of this response.
• Using a Compound Gain Field to Compute a Reach Plan
  - Neuron 64(5):744-755 (2009)
  A gain field, the scaling of a tuned neuronal response by a postural signal, may help support neuronal computation. Here, we characterize eye and hand position gain fields in the parietal reach region (PRR). Eye and hand gain fields in individual PRR neurons are similar in magnitude but opposite in sign to one another. This systematic arrangement produces a compound gain field that is proportional to the distance between gaze location and initial hand position. As a result, the visual response to a target for an upcoming reach is scaled by the initial gaze-to-hand distance. Such a scaling is similar to what would be predicted in a neural network that mediates between eye- and hand-centered representations of target location. This systematic arrangement supports a role of PRR in visually guided reaching and provides strong evidence that gain fields are used for neural computations.