Volume 8 Issue 8, August 2005

Voluntarily paying attention to one object in a crowded scene enhances perception of that object and increases the activity of neurons representing it. Attention can also be drawn involuntarily by salient objects—for example, by the sudden onset of a bright stimulus. A study now shows how this involuntary type of attention may mediate competition between representations in human visual cortex.

Aβ peptide is linked to Alzheimer pathology, but its toxic mechanism remains unclear. New work shows that Aβ leads to internalization of NMDA receptors, reducing their availability at synapses. The authors also suggest a molecular mechanism for this endocytosis.

A new paper shows that the transcription factor Dlx1, known to be involved in neuronal migration, is also necessary for interneuron survival. Mice lacking Dlx1 show subtype-specific loss of interneurons, a reduction in inhibitory currents and generalized seizures.

Cerebral cortex size in individuals and species is determined by cortical progenitor mitosis and death during embryogenesis. EphA signaling—important in axon guidance and patterning—also seems to be critical in regulating the survival of cortex progenitors.

Reward-sensitive neurons are present throughout the brain. A report in Science now shows that a subset of thalamic neurons respond selectively to the smaller of two rewards, as opposed to just reflecting reward magnitude, as do neurons in other brain areas.