Orientation dependence of the orientation-contingent face aftereffect

AbstractProlonged exposure to upright and inverted female and male faces produces opposite effects on subsequent judgments of the sex of faces depending on their orientation. We show that the magnitude of this orientation-contingent gender aftereffect can be predicted from simple aftereffects induced separately at the same orientations. The contingent aftereffect can also be induced in faces tilted 90° to the right and left, eliminating any difference in face-processing strategy that may be in operation with upright and inverted faces. This suggests that neurons employing a single face encoding strategy can be activated in an orientation-specific manner

Fixation related shifts of perceptual localization counter to saccade direction

Perisaccadic compression of the perceived location of flashed visual stimuli toward a saccade target occurs from about 50 ms before a saccade. Here we show that between 150 and 80 ms before a saccade, perceived locations are shifted toward the fixation point. To establish the cause of the ‘‘reverse’’ presaccadic perceptual distortion, participants completed several versions of a saccade task. After a cue to saccade, a probe bar stimulus was briefly presented within the saccade trajectory. In Experiment 1 participants made (a) overlap saccades with immediate return saccades, (b) overlap saccades, and (c) step saccades. In Experiment 2 participants made gap saccades in complete darkness. In Experiment 3 participants maintained fixation with the probe stimuli masked at various interstimulus intervals. Participants indicated the bar’s location using a mouse cursor. In all conditions in Experiment 1 presaccadic compression was preceded by compression toward the initial fixation. In Experiment 2, saccadic compression was maintained but the preceding countercompression was not observed. Stimuli masked at fixation were not compressed. This suggests the two opposing compression effects are related to the act of executing an eye movement. They are also not caused by the requirement to make two sequential saccades ending at the initial fixation location and are not caused by continuous presence of the fixation markers. We propose that countercompression is related to fixation activity and is part of the sequence of motor preparations to execute a cued saccade

Embryo collection induces transient activation of XBP1 arm of the ER stress response while embryo vitrification does not.

Embryo cryopreservation has become a standard procedure in the practice of assisted reproduction. While routinely performed in IVF labs, the effects of embryo vitrification on the molecular mechanisms governing preimplantation development remain largely unknown. The endoplasmic reticulum stress (ER stress) response is an evolutionary conserved mechanism that cells employ to manage ER stress. ER stress can be defined as an imbalance between protein synthesis and secretion within the ER. The primary focus of this study was to investigate whether standard embryo manipulations, including embryo collection, culture and vitrification, result in activation of the ER stress pathway in vitro and to determine whether the embryo utilizes the unfolded protein response as an adaptive response. Our results indicate that the major ER stress pathway constituents are present at all stages of preimplantation development and that the activation of ER stress pathways can be induced at the 8-cell, morula and blastocyst stages. Additionally, we have demonstrated that the IRE1α arm of the ER Stress pathway is activated in freshly collected embryos but contrastingly, this ER Stress arm is not activated following embryo vitrification. It is important to understand the possible stresses that Assisted Reproductive Technologies place on the embryo and the mechanisms the embryo employs to adapt to these stresses. This study indicates that among the adaptive pathways available, cultured mammalian embryos can employ the ER stress pathway. Assisted reproduction techniques should be aware that their activities may induce the ER stress pathway in their patients\u27 early embryos

Adaptation to geometrically skewed moving images : an asymmetrical effect on the double-drift illusion

Progressive addition lenses introduce distortions in the peripheral visual field that alter both form and motion perception. Here we seek to understand how our peripheral visual field adapts to complex distortions. The adaptation was induced across the visual field by geometrically skewed image sequences, and aftereffects were measured via changes in perception of the double-drift illusion. The double-drift or curveball stimulus contains both local and object motion. Therefore, the aftereffects induced by geometrical distortions might be indicative of how this adaptation interacts with the local and object motion signals. In the absence of the local motion components, the adaptation to skewness modified the perceived trajectory of object motion in the opposite direction of the adaptation stimulus skew. This effect demonstrates that the environment can also tune perceived object trajectories. Testing with the full double-drift stimulus, adaptation to a skew in the opposite direction to the local motion component induced a change in perception, reducing the illusion magnitude (when the stimulus was presented on the right side of the screen. A non-statistically significant shift, when stimuli were on the left side). However, adaptation to the other orientation resulted in no change in the strength of the double-drift illusion (for both stimuli locations). Thus, it seems that the adaptor's orientation and the motion statistics of the stimulus jointly define the perception of the measured aftereffect. In conclusion, not only size, contrast or drifting speed affects the double-drift illusion, but also adaptation to image distortions

Saccadic suppression in schizophrenia

About 40% of schizophrenia patients report discrete visual disturbances which could occur if saccadic suppression, the decrease of visual sensitivity around saccade onset, is impaired. Two mechanisms contribute to saccadic suppression: eeference copy processing and backwards masking. Both are reportedly altered in schizophrenia. However, saccadic suppression has not been investigated in schizophrenia. 17 schizophrenia patients and 18 healthy controls performed a saccadic suppression task using a Gabor stimulus with individually adjusted contrast, which was presented within an interval 300 ms around saccade onset. Visual disturbance scores were higher in patients than controls, but saccadic suppression strength and time course were similar in both groups with lower saccadic suppression rates being similarly related to smaller saccade amplitudes. Saccade amplitudes in the saccadic suppression task were reduced in patients, in contrast to unaltered amplitudes during a saccade control task. Notably, smaller saccade amplitudes were related to higher visual disturbances scores in patients. Saccadic suppression performance was unrelated to symptom expression and antipsychotic medication. Unaltered saccadic suppression in patients suggests sufficiently intact eeference copy processing and backward masking as required for this task. Instead, visual disturbances in patients may be related to restricted saccadic amplitudes arising from cognitive load while completing a task

Mismatch negativity/P3a complex in young people with psychiatric disorders : a cluster analysis

Background: We have recently shown that the event-related potential biomarkers, mismatch negativity (MMN) and P3a, are similarly impaired in young patients with schizophrenia- and affective-spectrum psychoses as well as those with bipolar disorder. A data driven approach may help to further elucidate novel patterns of MMN/P3a amplitudes that characterise distinct subgroups in patients with emerging psychiatric disorders. Methods: Eighty seven outpatients (16 to 30 years) were assessed: 19 diagnosed with a depressive disorder; 26 with a bipolar disorder; and 42 with a psychotic disorder. The MMN/P3a complex was elicited using a two-tone passive auditory oddball paradigm with duration deviant tones. Hierarchical cluster analysis utilising frontal, central and temporal neurophysiological variables was conducted. Results: Three clusters were determined: the 'globally impaired' cluster (n = 53) displayed reduced frontal and temporal MMN as well as reduced central P3a amplitudes; the 'largest frontal MMN' cluster (n = 17) were distinguished by increased frontal MMN amplitudes and the 'largest temporal MMN' cluster (n = 17) was characterised by increases in temporal MMN only. Notably, 55% of those in the globally impaired cluster were diagnosed with schizophrenia-spectrum disorder, whereas the three patient subgroups were equally represented in the remaining two clusters. The three cluster-groups did not differ in their current symptomatology; however, the globally impaired cluster was the most neuropsychologically impaired, compared with controls. Conclusions: These findings suggest that in emerging psychiatric disorders there are distinct MMN/P3a profiles of patient subgroups independent of current symptomatology. Schizophrenia-spectrum patients tended to show the most global impairments in this neurophysiological complex. Two other subgroups of patients were found to have neurophysiological profiles suggestive of quite different neurobiological (and hence, treatment) implications

Simulations of the OzDES AGN Reverberation Mapping Project

As part of the OzDES spectroscopic survey we are carrying out a large scale reverberation mapping study of $\sim$500 quasars over five years in the 30 deg$^2$ area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between $16.8<r<22.5$ mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission line fluxes of individual objects in order to measure black hole masses for a broad range of AGN and constrain the radius-luminosity ($R-L$) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for $\sim$35-45\% of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag, and objects with lags $\lesssim$6 months or $\sim$1 year are expected be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the $R-L$ relationship parameters for H$\beta$, Mg II $\lambda$2798, and C IV $\lambda$1549. However, extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission line flux measurement accuracy will significantly improve the $R-L$ parameter constraints for all broad emission lines.Comment: Published online in MNRAS. 28 page

Attenuation of visual evoked responses to hand and saccade-initiated flashes

Sensory attenuation refers to reduced brain responses to self-initiated sensations relative to those produced by the external world. It is a low-level process that may be linked to higher-level cognitive tasks such as reality monitoring. The phenomenon is often explained by prediction error mechanisms of universal applicability to sensory modality; however, it is most widely reported for auditory stimuli resulting from self-initiated hand movements. The present series of event-related potential (ERP) experiments explored the generalizability of sensory attenuation to the visual domain by exposing participants to flashes initiated by either their own button press or volitional saccade and comparing these conditions to identical, computer-initiated stimuli. The key results showed that the largest reduction of anterior visual N1 amplitude occurred for saccade-initiated flashes, while button press-initiated flashes evoked an intermediary response between the saccade-initiated and externally initiated conditions. This indicates that sensory attenuation occurs for visual stimuli and suggests that the degree of electrophysiological attenuation may relate to the causal likelihood of pairings between the type of motor action and the modality of its sensory response

Simulations of the OzDES AGN reverberation mapping project

As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ≥500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrain the radius-luminosity (R-L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for-35-45 per cent of the quasars. AGN with shorter lags and greater variability aremore likely to yield a lag measurement, and objects with lags ≲6 months or-1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R-L relationship parameters for H β, MgII λ2798, and CIV λ1549. Extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R-L parameter constraints for all broad emission lines

Climate change concerns impact on young Australians’ psychological distress and outlook for the future

Aims: Climate change is escalating and will disproportionately affect young people. Research on the mental health consequences of worry or concerns related to climate change are so far limited. This study aims to evaluate the extent of climate change concern in young people aged 15–19, its association with various demographic factors and its impact on psychological distress and future outlook. Understanding the impact of climate concerns on young people's mental wellbeing is crucial for identifying effective measures and building resilience. Methods: Climate concerns, psychological distress, and future outlook were measured in the 2022 Mission Australia Youth Survey, Australia's largest annual population-wide survey of young people aged 15 to 19 (N = 18,800). Multinomial logistic regression models were used to map factors associated with climate concerns and assess whether climate concerns are associated with psychological distress and future outlook. Results: One in four young people reported feeling very or extremely concerned about climate change. Climate concerns were higher among individuals identifying as female or gender diverse, or who self-reported a mental health condition. After controlling for confounding factors, we found those who were very or extremely concerned about climate change to be more likely to have high psychological distress than those not at all concerned (Relative risk ratio (RRR) = 1.81; 95% CI: 1.56–2.11), and more likely to have a negative future outlook (RRR = 1.52; 95% CI: 1.27–1.81). These associations were stronger among participants who reported to be gender diverse, Indigenous or from outer-regional/remote areas. Conclusion: This study identified associations between climate concerns, psychological distress, and future outlook among young people. Immediate attention from research and policy sectors to support climate change education, communication strategies and targeted interventions is urgently required to mitigate long-term impacts on young people's wellbeing.</p