Strategies for optical control and simultaneous electrical readout of extended cortical circuits.

BACKGROUND: To dissect the intricate workings of neural circuits, it is essential to gain precise control over subsets of neurons while retaining the ability to monitor larger-scale circuit dynamics. This requires the ability to both evoke and record neural activity simultaneously with high spatial and temporal resolution. NEW METHOD: In this paper we present approaches that address this need by combining micro-electrocorticography (µECoG) with optogenetics in ways that avoid photovoltaic artifacts. RESULTS: We demonstrate that variations of this approach are broadly applicable across three commonly studied mammalian species - mouse, rat, and macaque monkey - and that the recorded µECoG signal shows complex spectral and spatio-temporal patterns in response to optical stimulation. COMPARISON WITH EXISTING METHODS: While optogenetics provides the ability to excite or inhibit neural subpopulations in a targeted fashion, large-scale recording of resulting neural activity remains challenging. Recent advances in optical physiology, such as genetically encoded Ca(2+) indicators, are promising but currently do not allow simultaneous recordings from extended cortical areas due to limitations in optical imaging hardware. CONCLUSIONS: We demonstrate techniques for the large-scale simultaneous interrogation of cortical circuits in three commonly used mammalian species.

Parenting and survival in anthropoid primates: caretakers live longer.

Most anthropoid primates are slow to develop, their offspring are mostly single births, and the interbirth intervals are long. To maintain a stable population, parents must live long enough to sustain the serial production of a sufficient number of young to replace themselves while allowing for the death of offspring before they can reproduce. However, in many species there is a large differential between the sexes in the care provided to offspring. Therefore, we hypothesize that in slowly developing species with single births, the sex that bears the greater burden in the care of offspring will tend to survive longer. Males are incapable of gestating infants and lactating, but in several species fathers carry their offspring for long periods. We predict that females tend to live longer than males in the species where the mother does most or all of the care of offspring, that there is no difference in survival between the sexes in species in which both parents participate about equally in infant care, and that in the species where the father does a greater amount of care than the mother, males tend to live longer. The hypothesis is supported by survival data for males and females in anthropoid primate species.