| 1. |
- Luo, Sizuo, et al.
(författare)
-
Ultra-stable and versatile high-energy resolution setup for attosecond photoelectron spectroscopy
- 2023
-
Ingår i: Advances in Physics: X. - 2374-6149. ; 8:1
-
Forskningsöversikt (refereegranskat)abstract
- Attosecond photoelectron spectroscopy has opened up for studying light–matter interaction on ultrafast time scales. It is often performed with interferometric experimental setups that require outstanding stability. We demonstrate and characterize in detail an actively stabilized, versatile, high spectral resolution attosecond beamline based on a Mach-Zehnder interferometer. The active stabilization keeps the interferometer ultra-stable for several hours with an RMS stability of 13 as and a total pump-probe delay scanning range of (Formula presented.) fs. A tunable femtosecond laser source to drive high-order harmonic generation allows for precisely addressing atomic and molecular resonances. Furthermore, the interferometer includes a spectral shaper in 4f-geometry in the probe arm as well as a tunable bandpass filter in the pump arm, which offer additional high flexibility in terms of tunability as well as narrowband or polychromatic probe pulses. We demonstrate the capabilities of the beamline via experiments using several variants of the RABBIT (reconstruction of attosecond beating by two photon transitions) technique. In this setup, the temporal-spectral resolution of photoelectron spectroscopy can reach a new level of accuracy and precision.
|
|
| 2. |
- Borne, Kurtis D., et al.
(författare)
-
Ultrafast electronic relaxation pathways of the molecular photoswitch quadricyclane
- 2024
-
Ingår i: NATURE CHEMISTRY. - 1755-4330 .- 1755-4349. ; 16, s. 499-505
-
Tidskriftsartikel (refereegranskat)abstract
- The light-induced ultrafast switching between molecular isomers norbornadiene and quadricyclane can reversibly store and release a substantial amount of chemical energy. Prior work observed signatures of ultrafast molecular dynamics in both isomers upon ultraviolet excitation but could not follow the electronic relaxation all the way back to the ground state experimentally. Here we study the electronic relaxation of quadricyclane after exciting in the ultraviolet (201 nanometres) using time-resolved gas-phase extreme ultraviolet photoelectron spectroscopy combined with non-adiabatic molecular dynamics simulations. We identify two competing pathways by which electronically excited quadricyclane molecules relax to the electronic ground state. The fast pathway (<100 femtoseconds) is distinguished by effective coupling to valence electronic states, while the slow pathway involves initial motions across Rydberg states and takes several hundred femtoseconds. Both pathways facilitate interconversion between the two isomers, albeit on different timescales, and we predict that the branching ratio of norbornadiene/quadricyclane products immediately after returning to the electronic ground state is approximately 3:2.
|
|
| 3. |
- Busto, David, et al.
(författare)
-
Probing electronic decoherence with high-resolution attosecond photoelectron interferometry
- 2022
-
Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 76:7
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract: Quantum coherence plays a fundamental role in the study and control of ultrafast dynamics in matter. In the case of photoionization, entanglement of the photoelectron with the ion is a well-known source of decoherence when only one of the particles is measured. Here, we investigate decoherence due to entanglement of the radial and angular degrees of freedom of the photoelectron. We study two-photon ionization via the 2s2p autoionizing state in He using high spectral resolution photoelectron interferometry. Combining experiment and theory, we show that the strong dipole coupling of the 2s2p and 2p2 states results in the entanglement of the angular and radial degrees of freedom. This translates, in angle-integrated measurements, into a dynamic loss of coherence during autoionization. Graphic Abstract: [Figure not available: see fulltext.]. © 2022, The Author(s).
|
|
| 4. |
- Ebner, Natalie C., et al.
(författare)
-
Oxytocin modulates meta-mood as a function of age and sex
- 2015
-
Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media SA. - 1663-4365. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Attending to and understanding one's own feelings are components of meta mood and constitute important socio-affective skills across the entire lifespan. Growing evidence suggests a modulatory role of the neuropeptide oxytocin on various socio-affective processes. Going beyond previous work that almost exclusively examined young men and perceptions of emotions in others, the current study investigated effects of intranasal oxytocin on meta-mood in young and older men and women. In a double-blind between-group design, participants were randomly assigned to self-administer either intranasal oxytocin or a placebo before responding to items from the Trait Meta Mood Scale (TMMS) about attention to feelings and clarity of feelings. In contrast to older women, oxytocin relative to placebo increased attention to feelings in older men. Oxytocin relative to placebo enhanced meta-mood in young female participants but reduced it in older female participants. This pattern of findings supports an age- and sex-differential modulatory function of the neuropeptide oxytocin on meta-mood, possibly associated with neurobiological differences with age and sex.
|
|
| 5. |
- Ebner, Natalie C., et al.
(författare)
-
Oxytocin’s effect on resting-state functional connectivity varies by age and sex
- 2016
-
Ingår i: Psychoneuroendocrinology. - : Elsevier BV. - 0306-4530 .- 1873-3360. ; 69, s. 50-59
-
Tidskriftsartikel (refereegranskat)abstract
- The neuropeptide oxytocin plays a role in social cognition and affective processing. The neural processes underlying these effects are not well understood. Modulation of connectivity strength between subcortical and cortical regions has been suggested as one possible mechanism. The current study investigated effects of intranasal oxytocin administration on resting-state functional connectivity between amygdala and medial prefrontal cortex (mPFC), as two regions involved in social-cognitive and affective processing. Going beyond previous work that largely examined young male participants, our study comprised young and older men and women to identify age and sex variations in oxytocin’s central processes. This approach was based on known hormonal differences among these groups and emerging evidence of sex differences in oxytocin’s effects on amygdala reactivity and age-by-sex-modulated effects of oxytocin in affective processing. In a double-blind design, 79 participants were randomly assigned to self-administer either intranasal oxytocin or placebo before undergoing resting-state functional magnetic resonance imaging. Using a targeted region-to-region approach, resting-state functional connectivity strength between bilateral amygdala and mPFC was examined. Participants in the oxytocin compared to the placebo group and men compared to women had overall greater amygdala–mPFC connectivity strength at rest. These main effects were qualified by a significant three-way interaction: while oxytocin compared to placebo administration increased resting-state amygdala–mPFC connectivity for young women, oxytocin did not significantly influence connectivity in the other age-by-sex subgroups. This study provides novel evidence of age-by-sex differences in how oxytocin modulates resting-state brain connectivity, furthering our understanding of how oxytocin affects brain networks at rest.
|
|
| 6. |
- Ebner, Natalie, et al.
(författare)
-
Neuroplasticity and cognitive benefits associated with chronic intranasal oxytocin administration in aging
- 2019
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Oxytocin (OT) is a crucial chemical modulator of social behavior, and intranasal OT administration has potential as treatment for social deficits. Considerably less is known about OT’s effects on non-social cognition, a functional domain of particular relevance in aging. Brain mechanisms underlying OT’s benefits are not well understood but recent animal work suggests that repeated OT administration induces brain changes. To test this neuroplastic role of OT on the human brain and its potential for cognitive improvement in aging, we conducted a randomized double-blind study in older men (> 56 years), with 34 participants self-administering either 24 IUs OT or placebo (P) twice daily. Before and after 4-weeks intranasal administration, participants underwent MRI and processing speed assessment. Using voxel-based morphometry, gray matter (GM) volume was measured on T1-weighted anatomical images. Age, education, physical health, and image quality served as covariates and family-wise error rate determined statistical significance in regions of interest. Analyses were performed without awareness of the assigned treatment labels. Significant interactions between treatment (OT vs. P) and time (pre- vs. post-intervention) on GM volume for left amygdala, hippocampus, and putamen suggested increased regional GM volume following OT but not P. Further, OT-induced enlargement in putamen was associated with improved processing speed, while there was no brain−behavior correlation in the P group. These findings support the notion that amygdala, hippocampus, and putamen are key targets of OT’s neuroplastic potential on the human brain and chronic OT administration may constitute a potential treatment in counteracting cognitive decline in aging.
|
|
| 7. |
|
|
| 8. |
- Gulliford, Desiree, et al.
(författare)
-
Gender-differential effects of intranasal oxytocin on resting-state anterior cingulate activity
- 2017
-
Konferensbidrag (refereegranskat)abstract
- Introduction: As individuals age, there is an increased focus on social relationships (Carstensen, 2006). However, age-related changes in the brain can interfere with social functioning (Ebner, et al, 2012; Mather, et al, 2005; Ruffman, et al, 2008). While age-related changes in cognition are well studied, social-cognitive changes in aging are still underinvestigated, especially the brain mechanisms underlying this phenomenon. The administration of intranasal oxytocin (OT) has the potential to modulate social cognition (De Dreu, 2014) by altering BOLD signal in regions of the social brain (eg. amygdala and vmPFC) (Ebner, et al, 2016). Currently, there is very little known about the role of OT in human development in aging (Campbell, et al, 2014; Huffmeijer, et al, 2012). Methods: 40 young (18–31 years, 50% female) and 39 older (63–81 years, 59% female) were randomly assigned (in a double-blind design) to self-administer either 24 UIs of intranasal OT or placebo (P) 70-90 minutes prior to resting-state fMRI. T1-weighted anatomical reference images, using an MP-RAGE sequence (sagittal plane, FOV = 240 mm × 240 mm × 170; 1 × 1 × 1 mm isotropic voxels), and functional gradient-echo-planar imaging (EPI) data, during an open-eye, white cross-hair on black background, 8 minute resting-state scan (38 interleaved slices, TR 2 sec, TE 30 msec, FOV 252 × 252 × 133 mm, 80 × 80 × 38 mm matrix, flip angle 90°, in plane resolution of 3.15 × 3.15 mm, slice thickness 3.5 mm, 0 mm skip), were acquired with a 3T Philips Achieva MR Scanner using a 32-channel head coil. Preprocessing, including slice time correction, motion correction with artifact rejection, spatial normalization, and smoothing with an 8 mm Gaussian kernel, were implemented with Functional Connectivity Toolbox (Whitfield-Gabrieli, et al, 2012; http://www.nitrc.org/projects/conn/). Results: Younger individuals showed significantly greater overall anterior cingulate (AC) activity in P condition (p=.044). Intranasal OT administration significantly increased activity in the AC in both younger and older women (p=.024), but not men, when compared to P. The effect was slightly greater in older women than younger, but this effect was not significant potentially due to sample size.There were no significant gender effects in AC activity during rest between males and females in either younger or older P control groups. Conclusions: Intranasal OT has differential gender effects on AC activity during resting-state, increasing activity in women but not men. Additionally, there is evidence for age differences in overall AC activity at rest.
|
|
| 9. |
- Horta, Marilyn, et al.
(författare)
-
Oxytocin alters patterns of brain activity and amygdalar connectivity by age during dynamic facial emotion identification
- 2019
-
Ingår i: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 78, s. 42-51
-
Tidskriftsartikel (refereegranskat)abstract
- Aging is associated with increased difficulty in facial emotion identification, possibly due to age-related network change. The neuropeptide oxytocin (OT) facilitates emotion identification, but this is understudied in aging. To determine the effects of OT on dynamic facial emotion identification across adulthood, 46 young and 48 older participants self-administered intranasal OT or a placebo in a randomized, double-blind procedure. Older participants were slower and less accurate in identifying emotions. Although there was no behavioral treatment effect, partial least squares analysis supported treatment effects on brain patterns during emotion identification that varied by age and emotion. For young participants, OT altered the processing of sadness and happiness, whereas for older participants, OT only affected the processing of sadness (15.3% covariance, p = 0.004). Furthermore, seed partial least squares analysis showed that older participants in the OT group recruited a large-scale amygdalar network that was positively correlated for anger, fear, and happiness, whereas older participants in the placebo group recruited a smaller, negatively correlated network (7% covariance, p = 0.002). Advancing the literature, these findings show that OT alters brain activity and amygdalar connectivity by age and emotion.
|
|
| 10. |
- Lin, Tian, et al.
(författare)
-
Age-Related Differences in Amygdala Activation Associated With Face Trustworthiness but No Evidence of Oxytocin Modulation
- 2022
-
Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- The amygdala has been shown to be responsive to face trustworthiness. While older adults typically give higher face trustworthiness ratings than young adults, a direct link between amygdala response and age-related differences in face trustworthiness evaluation has not yet been confirmed. Additionally, there is a possible modulatory role of the neuropeptide oxytocin in face trustworthiness evaluation, but the results are mixed and effects unexplored in aging. To address these research gaps, young, and older adults were randomly assigned to oxytocin or placebo self-administration via a nasal spray before rating faces on trustworthiness while undergoing functional magnetic resonance imaging. There was no overall age-group difference in face trustworthiness ratings, but older compared to young participants gave higher trustworthiness ratings to ambivalently untrustworthy-looking faces. In both age groups, lower face trustworthiness ratings were associated with higher left amygdala activity. A comparable negative linear association was observed in right amygdala but only among young participants. Also, in the right amygdala, lower and higher, compared to moderate, face trustworthiness ratings were associated with greater right amygdala activity (i.e., positive quadratic (U-shaped) association) for both age groups. Neither the behavioral nor the brain effects were modulated by a single dose of intranasal oxytocin administration, however. These results suggest dampened response to faces with lower trustworthiness among older compared to young adults, supporting the notion of reduced sensitivity to cues of untrustworthiness in aging. The findings also extend evidence of an age-related positivity effect to the evaluation of face trustworthiness.
|
|
