Hot off the presses! Jul 01 nrn

The Jul 01 issue of the nrn is now up on Pubget (About nrn): 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:

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  - nrn 12(7):367 (2011)
  
• Auditory processing: Sounding out consciousness | PDF (284 KB)
  - nrn 12(7):369 (2011)
  Severe brain damage can lead to loss of consciousness, but it is notoriously difficult to diagnose whether patients are in a vegetative state or in a minimally conscious state — a problem that becomes especially pertinent when decisions have to be made regarding whether or not to prolong the life of such a patient. Currently, the distinction between the two conditions is based on behavioural differences, with only patients in a minimally conscious state showing some seemingly purposeful movements and, therefore, signs of awareness.
• Spatial coding: Oscillations maintain grid position | PDF (293 KB)
  - nrn 12(7):370 (2011)
  Neural oscillations in the theta frequency range (4–11 Hz) have been suggested to be involved in the coding of an animal's spatial location, but how they do so has not been determined. Two papers published recently in Science now show that the proper functioning of a key cell type involved in spatial coding — the grid cell — requires theta oscillations.
• Metabolism | Stress | Sensory systems | PDF (93 KB)
  - nrn 12(7):370 (2011)
  Brain PPAR-γ promotes obesity and is required for the insulin-sensitizing effect of thiazolidinediones Lu, M.et al. Nature Med. 17, 618–622 (2011)
• Evolution: Three major steps to a mammalian brain | PDF (359 KB)
  - nrn 12(7):371 (2011)
  Mammals arose approximately 200 million years ago and evolved brains up to ten times as large, relative to a given body weight, as those of their ancestors. The evolutionary steps leading to large and complex mammalian brains have been difficult to determine given the rarity of fossil skulls and, until recently, the need to destroy such skulls to expose the cranial cavity.
• Synaptic plasticity: Finely tuning caspase function | PDF (144 KB)
  - nrn 12(7):371 (2011)
  Caspase function is not limited to the realm of apoptosis: in rodent hippocampal neurons, for example, long-term depression (LTD) of synaptic transmission requires active caspase 3. How caspases are activated in non-apoptotic processes is unclear, as is why they do not induce cell death.
• Memory: The foundations of accurate recall | PDF (177 KB)
  - nrn 12(7):372 (2011)
  Learning is associated with a transient increase in synapse number, but little is known about how this contributes to memory formation and recall. In a study published in Nature, Caroni and colleagues show that learning specifically produces a rise in the number of synapses that trigger feedforward inhibition, which is crucial for memory precision.
• Neurodegenerative disease: Directing amyloid-β deposition | PDF (217 KB)
  - nrn 12(7):372 (2011)
  In Alzheimer's disease, the deposition of amyloid-β in the brain as insoluble extracellular amyloid plaques follows a region-specific pattern, but why certain regions are vulnerable to plaque development is unclear. Now, Holtzman and colleagues show that variation in basal neuronal activity across different brain regions might regulate the distribution of amyloid-β pathology.
• Autism: Converging pathways | PDF (374 KB)
  - nrn 12(7):372 (2011)
  Autism spectrum disorder (ASD) encompasses a range of cognitive and behavioural phenotypes, and the genetic and environmental factors that are thought to contribute to the disorder are equally diverse. Whether these factors converge onto common downstream pathogenic pathways is unclear.
• Stem cells | Sleep | Excitotoxicity | Neurodegenerative disease | PDF (98 KB)
  - nrn 12(7):373 (2011)
  Specification of transplantable astroglial subtypes from human pluripotent stem cellsKrencik, R.et al. Nature Biotechnol.20 May 2011 (doi:10.1038/nbt.1877)
• From the stochasticity of molecular processes to the variability of synaptic transmission
  - nrn 12(7):375 (2011)
  The variability of the postsynaptic response following a single action potential arises from two sources: the neurotransmitter release is probabilistic, and the postsynaptic response to neurotransmitter release has variable timing and amplitude. At individual synapses, the number of molecules of a given type that are involved in these processes is small enough that the stochastic (random) properties of molecular events cannot be neglected. How the stochasticity of molecular processes contributes to the variability of synaptic transmission, its sensitivity and its robustness to molecular fluctuations has important implications for our understanding of the mechanistic basis of synaptic transmission and of synaptic plasticity.
• Repertoire of microglial and macrophage responses after spinal cord injury
  - nrn 12(7):388 (2011)
  Macrophages from the peripheral circulation and those derived from resident microglia are among the main effector cells of the inflammatory response that follows spinal cord trauma. There has been considerable debate in the field as to whether the inflammatory response is good or bad for tissue protection and repair. Recent studies on macrophage polarization in non-neural tissues have shed much light on their changing functional states. In the context of this literature, we discuss the activation of macrophages and microglia following spinal cord injury, and their effects on repair. Harnessing their anti-inflammatory properties could pave the way for new therapeutic strategies for spinal cord trauma.
• Cognitive and neurobiological mechanisms of alcohol-related aggression
  - nrn 12(7):400 (2011)
  Alcohol-related violence is a serious and common social problem. Moreover, violent behaviour is much more common in alcohol-dependent individuals. Animal experiments and human studies have provided insights into the acute effect of alcohol on aggressive behaviour and into common factors underlying acute and chronic alcohol intake and aggression. These studies have shown that environmental factors, such as early-life stress, interact with genetic variations in serotonin-related genes that affect serotonergic and GABAergic neurotransmission. This leads to increased amygdala activity and impaired prefrontal function that, together, predispose to both increased alcohol intake and impulsive aggression. In addition, acute and chronic alcohol intake can further impair executive control and thereby facilitate aggressive behaviour.
• The benefits of noise in neural systems: bridging theory and experiment
  - nrn 12(7):415 (2011)
  Although typically assumed to degrade performance, random fluctuations, or noise, can sometimes improve information processing in non-linear systems. One such form of 'stochastic facilitation', stochastic resonance, has been observed to enhance processing both in theoretical models of neural systems and in experimental neuroscience. However, the two approaches have yet to be fully reconciled. Understanding the diverse roles of noise in neural computation will require the design of experiments based on new theory and models, into which biologically appropriate experimental detail feeds back at various levels of abstraction.
• Correspondence: Emotion in the brain: of low roads, high roads and roads less travelled
  - nrn 12(7):425 (2011)
  Traditionally, the cerebral cortex is considered the dominant player in understanding human brain functions, with subcortical structures relegated to a subservient role. In a recent Perspective article, Pessoa and Adolphs partly return to this traditional corticocentric view in the field of emotion processing (Emotion processing and the amygdala: from a 'low road' to 'many roads' of evaluating biological significance.
• From glutamate co-release to vesicular synergy: vesicular glutamate transporters
  - nrn 12(7):425 (2011)
  On page 209 of the above article, 'Nucleus accumbensb33-35, neostriatum33-35' should be listed under 'Terminals' not 'Cell bodies'. The online version of the article has been corrected accordingly.