Value-Based Search Efficiency Is Encoded in the Substantia Nigra Reticulata Firing Rate, Spiking Irregularity and Local Field Potential

Recent results show that valuable objects can pop out in visual search, yet its neural mechanisms remain unexplored. Given the role of substantia nigra reticulata (SNr) in object value memory and control of gaze, we recorded its single-unit activity while male macaque monkeys engaged in efficient or inefficient search for a valuable target object among low-value objects. The results showed that efficient search was concurrent with stronger inhibition and higher spiking irregularity in the target-present (TP) compared with the target-absent (TA) trials in SNr. Importantly, the firing rate differentiation of TP and TA trials happened within ∼100 ms of display onset, and its magnitude was significantly correlated with the search times and slopes (search efficiency). Time-frequency analyses of local field potential (LFP) after display onset revealed significant modulations of the gamma band power with search efficiency. The greater reduction of SNr firing in TP trials in efficient search can create a stronger disinhibition of downstream superior colliculus, which in turn can facilitate saccade to obtain valuable targets in competitive environments.

The Effects of Transcranial Direct Current Stimulation (tDCS) on the Cognitive Functions: A Systematic Review and Meta-analysis

Previous studies have investigated the effect of transcranial direct current stimulation (tDCS) on cognitive functions. However, these studies reported inconsistent results due to differences in experiment design, measurements, and stimulation parameters. Nonetheless, there is a lack of meta-analyses and review studies on tDCS and its impact on cognitive functions, including working memory, inhibition, flexibility, and theory of mind. We performed a systematic review and meta-analysis of tDCS studies published from the earliest available data up to October 2021, including studies reporting the effects of tDCS on cognitive functions in human populations. Therefore, these systematic review and meta-analysis aim to comprehensively analyze the effects of anodal and cathodal tDCS on cognitive functions by investigating 69 articles with a total of 5545 participants. Our study reveals significant anodal tDCS effects on various cognitive functions. Specifically, we observed improvements in working memory reaction time (RT), inhibition RT, flexibility RT, theory of mind RT, working memory accuracy, theory of mind accuracy and flexibility accuracy. Furthermore, our findings demonstrate noteworthy cathodal tDCS effects, enhancing working memory accuracy, inhibition accuracy, flexibility RT, flexibility accuracy, theory of mind RT, and theory of mind accuracy. Notably, regarding the influence of stimulation parameters of tDCS on cognitive functions, the results indicated significant differences across various aspects, including the timing of stimulation (online vs. offline studies), population type (clinical vs. healthy studies), stimulation duration (< 15 min vs. > 15 min), electrical current intensities (1-1.5 m.A vs. > 1.5 m.A), stimulation sites (right frontal vs. left frontal studies), age groups (young vs. older studies), and different cognitive tasks in each cognitive functioning aspect. In conclusion, our results demonstrate that tDCS can effectively enhance cognitive task performance, offering valuable insights into the potential benefits of this method for cognitive improvement.

Conspiracy beliefs are associated with a reduction in frontal beta power and biases in categorizing ambiguous stimuli

Prior beliefs, such as conspiracy beliefs, significantly influence our perception of the natural world. However, the brain activity associated with perceptual decision-making in conspiracy beliefs is not well understood. To shed light on this topic, we conducted a study examining the EEG activity of believers, and skeptics during resting state with perceptual decision-making task. Our study shows that conspiracy beliefs are related to the reduced power of beta frequency band. Furthermore, skeptics tended to misclassify ambiguous face stimuli as houses more frequently than believers. These results help to explain the differences in brain activity between believers and skeptics, especially in how conspiracy beliefs impact the categorization of ambiguous stimuli.

Resting-State Electroencephalogram (EEG) Coherence Over Frontal Regions in Paranormal Beliefs

Introduction

Paranormal beliefs are defined as the belief in extrasensory perception, precognition, witchcraft, and telekinesis, magical thinking, psychokinesis, superstitions. Previous studies corroborate that executive brain functions underpin paranormal beliefs. To test this hypotheses, neurophysiological studies of brain activity are required.

Methods

A sample of 20 students (10 girls, Mean±SD age: 22.50±4.07 years) were included in the current study. The absolute power of resting-state electroencephalogram (EEG) was analyzed in intra-hemispheric and inter-hemispheric coherence with eyes open. The paranormal beliefs were determined based on the total score of the revised paranormal belief scale (RPBS).

Results

The results of this study demonstrated a significant negative relationship between paranormal beliefs and resting-state EEG in alpha band activity in the frontal lobe (left hemisphere), EEG coherence of alpha and β1, β2, and gamma band activities in the frontal lobe (right hemisphere) and coherence of alpha and β1, β2 and gamma band activities between frontal regions (two hemispheres). In addition, the results showed that coherence of α, α1, β, and β2 band activities between the frontal lobe (right hemispheres) and the EEG coherence of Δ, α1, and beta band activities in the frontal lobe (two hemispheres) predict paranormal beliefs.

Conclusion

This study confirms the connection of executive brain functions to paranormal beliefs and determines that frontal brain function may contribute to paranormal beliefs.

Highlights

Paranormal beliefs were negatively related to the EEG coherence.Paranormal beliefs were associated with EEG coherence in the right frontal lobe.We found a negative correlation between paranormal beliefs and the EEG coherence in the frontal lobes.EEG coherence the frontal lobes predicted paranormal beliefs.

Plain Language Summary

Paranormal beliefs were negatively related to the EEG coherence. They were associated with EEG coherence in the right frontal lobe. In this study, we found a negative correlation between paranormal beliefs and the EEG coherence in the frontal lobes. EEG coherence the frontal lobes predicted paranormal beliefs.

The Role of Cognitive Control in Paranormal Beliefs: A Study Based on Performance in Go/No-Go Task

Cognitive control plays a role in human behavior and mental processes, and paranormal beliefs seem to be affected. This study aimed to investigate the role of cognitive control in Paranormal Beliefs using the Go/No-Go Task. Ninety-two people were selected based on low, middle, and high scores in the Revised Paranormal Belief Scale(R-PBS) (Tobacyk, 2004) and were classified into three groups. This produced 30 Severe Paranormal Believers (13 females, mean age 25.3 years), 31 Mild Paranormal Believers (14 females, mean age 26.4 years), and 31 Skeptics (16 females, mean age 25.8 years). All participants were tested on the Go/No Go Task. A multivariate analysis of variance was conducted with the group (Severe Paranormal Believers, Mild Paranormal Believers, and Skeptics) as the independent variable and the Go/No Go subscales scores as dependent variables. The findings show that there is a significant difference between the mean scores in Errors( Go) (F2,89=7.20, p=0.01) , Errors(No- Go) (F2,89=11. 81, p=0.01) and Reaction Time (F2,89=21.46, p=0.01) between the groups. The Severe Paranormal Believers and Mild Paranormal Believers had lower accuracy and slower RT than the Skeptics group. Therefore, Severe Paranormal Believers and Mild Paranormal Believers had a weakness in all Go/No-Go subscale scores. This finding suggests that paranormal beliefs may related to poor cognitive control.

Investigating the Role of Brain Lateralization and Gender in Paranormal Beliefs

Introduction:

Brain lateralization is associated with human behavior. Therefore, this study aimed at investigating the effects of brain lateralization on the scores of paranormal beliefs.

Methods:

The study population included 180 students of Sanandaj universities, Sanandaj City, Iran who were selected with convenience sampling method (100 left-brained males, 6 left-brained females, 56 both left- and right-brained males and 22 both left- and right-brained females). The research tools were the paranormal belief scale developed by Blackmore (1994), as well as the brain lateralization questionnaire (1985).

Results:

The obtained findings suggested a significant difference between the left-brain and right-brained people in terms of paranormal beliefs. A significant difference was also found between the left-brained males and both left- and right-brained females in terms of paranormal beliefs.

Conclusion:

The paranormal beliefs of the left-brained cases were different from both left- and right-brained subjects, which can be seen between the left-brained males and both left- and right-brained females.