We present XMM-Newton observations of the radio galaxy 3C 120. Contemporaneous radio, millimeter-wave, and optical data provide additional constraints on the spectral energy distribution and physical state of the active galactic nucleus. The hard X-ray spectrum contains a marginally resolved Fe I Kα emission line with FWHM = 9000 × 3000 km s-1 and an equivalent width of 57 ± 7 eV. The line arises via fluorescence in a broad-line region with covering fraction of 0.4. There is no evidence of relativistically broad Fe Kα, contrary to some previous reports. An excess of 0.3-2 keV soft X-ray continuum over an extrapolation of the hard X-ray power law may arise in a disk corona. A break in the X-ray spectrum below 0.6 keV indicates an excess neutral hydrogen column density of NE = (1.0-1.6) × 1021 cm-2. However, the neutral absorber must have an oxygen abundance of <1/40 of the solar value to explain the absence of an intrinsic or intervening O I edge. There is no ionized absorption in the soft X-ray spectrum, and we do not detect previously claimed 0 VIII absorption from the intervening intergalactic medium. Radio observations at 37 GHz show a fast, high-frequency flare beginning near the time of the XMM-Newton observation, which has no obvious effect on the X-ray spectrum. The X-ray spectrum, including the soft excess, became harder as the X-ray flux decreased, with an estimated pivot energy of 40 keV. The UVand soft X-ray fluxes are strongly correlated over the 120 ks duration of the XMM-Newton observation. This is qualitatively consistent with Comptonization of UV photons by a hot corona.

Working memory (WM) is assumed to consist of a process that sustains memory representations in an active state (maintenance) and a process that operates on these activated representations (manipulation). We examined evidence for two distinct, concurrent cognitive functions supporting maintenance and manipulation abilities by testing brain activity as participants performed a WM alphabetization task. Maintenance was investigated by varying the number of letters held in WM and manipulation by varying the number of moves required to sort the list alphabetically. We found that both maintenance and manipulation demand had significant effects on behavior that were associated with different cortical regions: maintenance was associated with bilateral prefrontal and left parietal cortex, and manipulation with right parietal activity, a link that is consistent with the role of parietal cortex in symbolic computations. Both structural and functional architecture of these systems suggested that these cognitive functions are supported by two dissociable brain networks. Critically, maintenance and manipulation functional networks became increasingly segregated with increasing demand, an effect that was positively associated with individual WM ability. These results provide evidence that network segregation may act as a protective mechanism to enable successful performance under increasing WM demand.

Working memory is the ability to perform mental operations on information that is stored in a flexible, limited capacity buffer. The ability to manipulate information in working memory is central to many aspects of human cognition, but also declines with healthy aging. Given the profound importance of such working memory manipulation abilities, there is a concerted effort towards developing approaches to improve them. The current study tested the capacity to enhance working memory manipulation with online repetitive transcranial magnetic stimulation in healthy young and older adults. Online high frequency (5Hz) repetitive transcranial magnetic stimulation was applied over the left dorsolateral prefrontal cortex to test the hypothesis that active repetitive transcranial magnetic stimulation would lead to significant improvements in memory recall accuracy compared to sham stimulation, and that these effects would be most pronounced in working memory manipulation conditions with the highest cognitive demand in both young and older adults. Repetitive transcranial magnetic stimulation was applied while participants were performing a delayed response alphabetization task with three individually-titrated levels of difficulty. The left dorsolateral prefrontal cortex was identified by combining electric field modeling to individualized functional magnetic resonance imaging activation maps and was targeted during the experiment using stereotactic neuronavigation with real-time robotic guidance, allowing optimal coil placement during the stimulation. As no accuracy differences were found between young and older adults, the results from both groups were collapsed. Subsequent analyses revealed that active stimulation significantly increased accuracy relative to sham stimulation, but only for the hardest condition. These results point towards further investigation of repetitive transcranial magnetic stimulation for memory enhancement focusing on high difficulty conditions as those most likely to exhibit benefits.