Effects of repetitive transcranial magnetic stimulation combined with cognitive training on resting-state brain activity in Alzheimer’s disease

Objectives Repetitive transcranial magnetic stimulation (rTMS) is a promising tool to modulate brain plasticity, but the neural basis has been little addressed. The purpose was to investigate the effects of rTMS on resting-state brain activity in patients with Alzheimer’s disease (AD). Methods Seventeen patients with mild or moderate AD were enrolled and randomly divided into one of the two intervention groups: (1) real rTMS combined with cognitive training (real group, n = 9); (2) sham rTMS with cognitive training (sham group, n = 8). 10 Hz rTMS was used to stimulate the left dorsolateral prefrontal cortex and then the left lateral temporal lobe for 20 min each day for 4 weeks. Each patient underwent neuropsychological assessment and resting-state functional magnetic resonance imaging (rsfMRI) before and after treatment. The fractional amplitude of low frequency fluctuation (fALFF) of rsfMRI data in real group were: (1) compared to sham; (2) correlated with rTMS-induced cognitive alterations. Results Significantly increased fALFF in right cerebellum/declive, left lingual/cuneus and left cingulate gyrus, as well as decreased fALFF in left middle frontal gyrus were found after 10 Hz rTMS, but not after sham stimulation. Using these suprathreshold regions, we found that rTMS increased functional connectivity between the right cerebellum/declive and left precentral/postcentral gyrus. The fALFF increase in left lingual/cuneus and right cerebellum/declive was associated with significant improvement in cognitive function. Conclusions rTMS combined with cognitive training induced increased low frequency fluctuation neural oscillations and functional connectivity in brain regions subserving cognition, suggesting a possible neuronal mechanism of the beneficial effects of rTMS.

Morally Homogeneous Networks and Radicalism

Online radicalization is among the most vexing challenges the world faces today. Here, we demonstrate that homogeneity in moral concerns results in increased levels of radical intentions. In Study 1, we find that in Gab—a right-wing extremist network—the degree of moral convergence within a cluster predicts the number of hate-speech messages members post. In Study 2, we replicate this observation in another extremist network, Incels. In Studies 3 to 5 ( N = 1,431), we demonstrate that experimentally leading people to believe that others in their hypothetical or real group share their moral views increases their radical intentions as well as willingness to fight and die for the group. Our findings highlight the role of moral convergence in radicalization, emphasizing the need for diversity of moral worldviews within social networks.

Distinctive Negative Reactions to Intermediate Social Groups (manuscript & supplement) 2021-10-31

Although considerable research has examined how members of advantaged groups think and feel about disadvantaged groups, fewer studies have examined responses to “intermediate” social groups—groups that are perceived as falling between traditionally recognized advantaged and disadvantaged groups. We measured judgments of intermediate groups, including novel groups designed to manipulate social group intermediacy (Studies 1-5), Black/White biracial people (Study 6), and bisexual people (Study 7). In each study, participants provided separate evaluations of an intermediate group and two comparison groups (e.g., Black/White biracial people, Black people, White people). Intermediate groups were consistently rated as less conceptually legitimate (e.g., less distinctive, not a “real” group) than other groups. The view that intermediate groups are not “real” groups helped explain negative evaluations of them, and participants who strongly identified with an advantaged ingroup were especially prone to this pattern of judgments. These results are consistent with the idea that an intermediate group can threaten the distinctiveness of a valued ingroup, leading people to dismiss and denigrate the intermediate group. Studying perceptions of intermediate groups facilitates a nuanced account of an increasingly heterogeneous social world.

Inaccurate Stereotypes from Rational Exploration

Inaccurate stereotypes -- perceived differences among groups that do not actually differ -- are prevalent and consequential. Past research explains stereotypes as emerging from motivational biases, cognitive limitations, and information deficits. An alternative proposal focuses on exploration: An initial arbitrary interaction, if rewarding enough, may discourage investigating alternatives that would be equal or better. Historical accidents can snowball, through locally rational choices, into globally inaccurate generalizations. Thus, inaccurate stereotypes can emerge from otherwise rational exploration, even in the absence of real group differences. Ironically, the mere act of rationally choosing between groups with the goal of maximizing the long-term benefit of local interactions is enough to produce globally inaccurate stereotypes. Formally describing this problem using multi-armed bandits shows how an optimal solution with existing psychological support (Thompson sampling) produces inaccurate stereotypes. This result replicates in two large online experiments (N = 2404). This minimal-process paradigm thus suffices to produce bias.

Effect of Neurofeedback Facilitation on Post-stroke Gait and Balance Recovery: A Randomized Controlled Trial

Objective:To test the hypothesis that supplementary motor area (SMA) facilitation with functional near-infrared spectroscopy mediated neurofeedback (fNIRS-NFB) augments post-stroke gait and balance recovery. Using the 3-meter-Timed Up-and-Go (TUG) test, we conducted this two-center, double-blind, randomized controlled trial involving 54 Japanese patients.Methods:Patients with subcortical stroke-induced mild-to-moderate gait disturbance more than 12 weeks from onset, underwent 6 sessions of SMA neurofeedback facilitation during gait- and balance-related motor imagery using fNIRS-NFB. Participants were randomly allocated to intervention (REAL: 28 patients) or placebo (SHAM: 26 patients) group. In the REAL group, the fNIRS signal contained participants’ cortical activation information. Primary outcome was TUG improvement, 4 weeks post intervention.Results:The REAL group showed greater improvement in the TUG test (12.84 ± 15.07 s, 95% CI: 7.00-18.68) than the SHAM group (5.51± 7.64 s, 95% CI: 2.43 – 8.60; group difference 7.33 s, 95% CI: 0.83 – 13.83; p = 0.028), even after adjusting for covariates (group × time interaction; F1.23,61.69 = 4.50, p = 0.030, partial η2 = 0.083). Only the REAL group showed significantly increased imagery-related SMA activation and enhancement of resting-state connectivity between SMA and ventrolateral premotor area. Adverse effects associated with fNIRS-mediated neurofeedback intervention were absent.Conclusion:SMA facilitation during motor imagery using fNIRS neurofeedback may augment post-stroke gait and balance recovery by modulating the SMA and its related network.Classification of Evidence:This study provides Class III evidence that for patients with gait disturbance from subcortical stroke, SMA neurofeedback facilitation improves TUG time.

Group decisions based on confidence weighted majority voting

Background It has repeatedly been reported that, when making decisions under uncertainty, groups outperform individuals. Real groups are often replaced by simulated groups: Instead of performing an actual group discussion, individual responses are aggregated by a numerical computation. While studies have typically used unweighted majority voting (MV) for this aggregation, the theoretically optimal method is confidence weighted majority voting (CWMV)—if independent and accurate confidence ratings from the individual group members are available. To determine which simulations (MV vs. CWMV) reflect real group processes better, we applied formal cognitive modeling and compared simulated group responses to real group responses. Results Simulated group decisions based on CWMV matched the accuracy of real group decisions, while simulated group decisions based on MV showed lower accuracy. CWMV predicted the confidence that groups put into their group decisions well. However, real groups treated individual votes to some extent more equally weighted than suggested by CWMV. Additionally, real groups tend to put lower confidence into their decisions compared to CWMV simulations. Conclusion Our results highlight the importance of taking individual confidences into account when simulating group decisions: We found that real groups can aggregate individual confidences in a way that matches statistical aggregations given by CWMV to some extent. This implies that research using simulated group decisions should use CWMV instead of MV as a benchmark to compare real groups to.

An orthogonality relation for (with an appendix by Bingrong Huang)

Orthogonality is a fundamental theme in representation theory and Fourier analysis. An orthogonality relation for characters of finite abelian groups (now recognized as an orthogonality relation on $\mathrm {GL}(1)$ ) was used by Dirichlet to prove infinitely many primes in arithmetic progressions. Orthogonality relations for $\mathrm {GL}(2)$ and $\mathrm {GL}(3)$ have been worked on by many researchers with a broad range of applications to number theory. We present here, for the first time, very explicit orthogonality relations for the real group $\mathrm {GL}(4, \mathbb R)$ with a power savings error term. The proof requires novel techniques in the computation of the geometric side of the Kuznetsov trace formula.

Learning via Virtual and Real Museums

The aim of study is to compare the contributions of virtual and real museum tours in terms of perceived presence and knowledge retention. The sample of study which was 28 third graders enrolled in a public primary school in an informal instructional process. There were two groups (virtual group and real group); one visited virtual museum (n=14), and the other (n=14) visited real one. Semi-structured interview form and student drawings were used to discuss students' evaluations about two environments. The results suggested that students who have attended virtual museum tour remember much more about the events and objects than students who have visited real museum tour. Students who attended virtual museum tours had perceived presence mostly as much as and in some cases, more than the real group students. Implementations for designing virtual and real museums for feeling more presence and contributing to knowledge retention are also included.