Cerebral Activation During Initial Motor Learning Forecasts Subsequent Sleep-Facilitated Memory Consolidation in Older Adults.

Older adults exhibit deficits in motor memory consolidation; however, little is known about the cerebral correlates of this impairment. We thus employed fMRI to investigate the neural substrates underlying motor sequence memory consolidation, and the modulatory influence of post-learning sleep, in healthy older adults. Participants were trained on a motor sequence and retested following an 8-h interval including wake or diurnal sleep as well as a 22-h interval including a night of sleep.

Active Fourier-transform spectroscopy combining the direct RF beating of two fiber-based mode-locked lasers with a novel referencing method.

A new approach is described to compensate the variations induced by laser frequency instabilities in the recently demonstrated Fourier transform spectroscopy that is based on the RF beating spectra of two frequency combs generated by mode-locked lasers. The proposed method extracts the mutual fluctuations of the lasers by monitoring the beating signal for two known optical frequencies. From this information, a phase correction and a new time grid are determined that allow the full correction of the measured interferograms.