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There is increasing evidence of widespread Ca2+waves and localized spark-like events in neurons, particularly in dendrites; however, their origin and function is still poorly understood. This article reviews emerging data on the nature of these signals, their spatial distribution and potential roles.
Processing within neural circuits in the retina extracts information about the direction of motion of images projected onto the retina. Vaney and colleagues describe the cellular components of this circuitry and outline our current understanding of the mechanisms that are involved in generating direction-selective responses in the retina.
The notion that the disruption of inhibitory circuits might underlie certain clinical features — notably cognitive impairment — in various neuropsychiatric disorders, including schizophrenia and autism, is receiving considerable attention. Focusing heavily on studies in animal models, Oscar Marín reviews the evidence indicating that the basis of such disruption is linked to specific defects in interneuron development and function.
The neurotransmitters expressed by neurons were thought to be fixed, but recent evidence suggests that during development, and also in the mature nervous system, neurotransmitter expression can be respecified by activity. This respecification seems to have a homeostatic role at synapses and influences behaviour.
Cognition results from large-scale interactions among widely distributed brain regions. Siegel and colleagues review studies showing that these interactions are reflected by correlated neuronal oscillations. They propose that correlated oscillations in large-scale cortical networks may be 'fingerprints' of canonical neuronal computations underlying cognitive processes.
The distribution of mitochondria to regions of the neuron that have the greatest requirement for ATP supply maintenance and sequestration of Ca2+is essential for neuronal function. Sheng and Cai describe the molecular mechanisms regulating mitochondrial transport in neurons and discuss its contribution to aspects of neuronal function.
