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Bystron and colleagues report a new population of neurons in the primordial cortex of 31-day-old human embryos. These cells, which may be the first neurons of the human cortex, are not generated from the local ventricular zone, but immigrate into the cortical domain from an unknown outside source. The cover shows one of these 'predecessor neurons', stained golden for βIII-tubulin, atop the cortical ventricular zone. All cell nuclei are labeled blue. (pp 867 and 880)
The anterior cingulate cortex (ACC) is thought to detect unfavorable outcomes and thus influence behavior. A new paper reports that ACC-lesioned monkeys respond normally to reduced rewards, but do not maintain their improved behavioral strategy. The ACC thus is not a simple error detector, but an integrator of past reward experience.
Microglia are thought to contribute to neurodegeneration. Now ablating the receptor for the chemokine fractalkine is shown to increase microglial inflammatory response and neuronal death in vivo in several models of CNS insult.
How does the decision-making process stop? Lo and Wang propose that a large-scale interconnected network encompassing parietal cortex, basal ganglia and motor structures controls the balance between speed and accuracy.
Lapses in attention can impair performance independent of the task. A new imaging study reports that reduced activity in prefrontal attentional control regions at the beginning of a trial predicts longer reaction times.
In Parkinson disease and related disorders, nitric oxide may disable PDI, an enzyme critical for proper protein folding in the endoplasmic reticulum, resulting in the accumulation of damaged proteins and eventually neuronal death.