On-orbit performance of the MIPS instrument

The Multiband Imaging Photometer for Spitzer (MIPS) provides long wavelength capability for the mission, in imaging bands at 24, 70, and 160 microns and measurements of spectral energy distributions between 52 and 100 microns at a spectral resolution of about 7%. By using true detector arrays in each band, it provides both critical sampling of the Spitzer point spread function and relatively large imaging fields of view, allowing for substantial advances in sensitivity, angular resolution, and efficiency of areal coverage compared with previous space far-infrared capabilities. The Si:As BIB 24 micron array has excellent photometric properties, and measurements with rms relative errors of 1% or better can be obtained. The two longer wavelength arrays use Ge:Ga detectors with poor photometric stability. However, the use of 1.) a scan mirror to modulate the signals rapidly on these arrays, 2.) a system of on-board stimulators used for a relative calibration approximately every two minutes, and 3.) specialized reduction software result in good photometry with these arrays also, with rms relative errors of less than 10%

DNA methylation regulates associative reward learning

Reward-related memories are essential for adaptive behavior and evolutionary fitness, but are also a core component of maladaptive brain diseases such as addiction. Reward learning requires dopamine neurons located in the ventral tegmental area (VTA), which encode relationships between predictive cues and future rewards. Recent evidence suggests that epigenetic mechanisms, including DNA methylation, are essential regulators of neuronal plasticity and experience-driven behavioral change. However, the role of epigenetic mechanisms in reward learning is poorly understood. Here, we reveal that the formation of reward-related associative memories in rats upregulates key plasticity genes in the VTA, which are correlated with memory strength and associated with gene-specific changes in DNA methylation. Moreover, DNA methylation in the VTA is required for the formation of stimulus-reward associations. These results provide the first evidence that that activity-dependent methylation and demethylation of DNA is an essential substrate for the behavioral and neuronal plasticity driven by reward-related experiences. Keyword