Combined factors effect of menstrual cycle and background noise on visual inspection task performance: a simulation-based task

Individual differences in mental imagery in different modalities and levels of intentionality

Mental imagery is a highly common component of everyday cognitive functioning. While substantial progress is being made in clarifying this fundamental human function, much is still unclear or unknown. A more comprehensive account of mental imagery aspects would be gained by examining individual differences in age, sex, and background experience in an activity and their association with imagery in different modalities and intentionality levels. The current online study combined multiple imagery self-report measures in a sample (n = 279) with a substantial age range (18-65 years), aiming to identify whether age, sex, or background experience in sports, music, or video games were associated with aspects of imagery in the visual, auditory, or motor stimulus modality and voluntary or involuntary intentionality level. The findings show weak positive associations between age and increased vividness of voluntary auditory imagery and decreased involuntary musical imagery frequency, weak associations between being female and more vivid visual imagery, and relations of greater music and video game experience with higher involuntary musical imagery frequency. Moreover, all imagery stimulus modalities were associated with each other, for both intentionality levels, except involuntary musical imagery frequency, which was only related to higher voluntary auditory imagery vividness. These results replicate previous research but also contribute new insights, showing that individual differences in age, sex, and background experience are associated with various aspects of imagery such as modality, intentionality, vividness, and frequency. The study's findings can inform the growing domain of applications of mental imagery to clinical and pedagogical settings.

Influence of Menstrual Cycle Phases on Neural Excitability in the Primary Somatosensory Cortex and Ankle Joint Position Sense

Introduction: Ankle sprain (AS) is one of the most common injuries among women engaged in competitive sports and recreational activities. Many studies have shown that several factors contributing to AS are influenced by the menstrual cycle. Despite the finding that abnormal joint position sense (JPS) is one of the major risk factors of AS, the alteration of the JPS throughout the menstrual cycle and its associated neural mechanisms remain unclear.

Objective: This study aimed to examine whether the menstrual cycle phases affect neural excitability in the primary somatosensory cortex (S1) and JPS.

Methods: Fourteen right-footed women participated in this study. Somatosensory-evoked potential and paired-pulse inhibition (PPI) were measured to assess S1 excitatory and inhibitory functions. Ankle JPS was measured using an active joint position matching method. Menstrual syndrome was evaluated using the menstrual distress questionnaire. All assessments were conducted in the follicular, ovulatory, and luteal phases.

Results: The two main findings of this study were as follows: First, PPI decreased in the ovulatory phase than in the follicular phase. This may have been the reason for estrogen altering the neural inhibition and facilitation balance throughout the menstrual cycle. Second, JPS was not changed during the menstrual cycle.

Conclusion: In conclusion, phases of the menstrual cycle affect the neural excitability in S1 as shown by the decreased PPI in the ovulatory phase, and the ankle JPS was unchanged throughout the menstrual cycle.

Early visual processing is enhanced in the midluteal phase of the menstrual cycle

Event-related potential (ERP) studies have revealed an early attentional bias in processing unpleasant emotional images in women. Recent neuroimaging data suggests there are significant differences in cortical emotional processing according to menstrual phase. This study examined the impact of menstrual phase on visual emotional processing in women compared to men. ERPs were recorded from 28 early follicular women, 29 midluteal women, and 27 men while they completed a passive viewing task of neutral and low- and high- arousing pleasant and unpleasant images. There was a significant effect of menstrual phase in early visual processing, as midluteal women displayed significantly greater P1 amplitude at occipital regions to all visual images compared to men. Both midluteal and early follicular women displayed larger N1 amplitudes than men (although this only reached significance for the midluteal group) to the visual images. No sex or menstrual phase differences were apparent in later N2, P3, or LPP. A condition effect demonstrated greater P3 and LPP amplitude to highly-arousing unpleasant images relative to all other stimuli conditions. These results indicate that women have greater early automatic visual processing compared to men, and suggests that this effect is particularly strong in women in the midluteal phase at the earliest stage of visual attention processing. Our findings highlight the importance of considering menstrual phase when examining sex differences in the cortical processing of visual stimuli.

Chronic exposure to low frequency noise at moderate levels causes impaired balance in mice

We are routinely exposed to low frequency noise (LFN; below 0.5 kHz) at moderate levels of 60-70 dB sound pressure level (SPL) generated from various sources in occupational and daily environments. LFN has been reported to affect balance in humans. However, there is limited information about the influence of chronic exposure to LFN at moderate levels for balance. In this study, we investigated whether chronic exposure to LFN at a moderate level of 70 dB SPL affects the vestibule, which is one of the organs responsible for balance in mice. Wild-type ICR mice were exposed for 1 month to LFN (0.1 kHz) and high frequency noise (HFN; 16 kHz) at 70 dB SPL at a distance of approximately 10-20 cm. Behavior analyses including rotarod, beam-crossing and footprint analyses showed impairments of balance in LFN-exposed mice but not in non-exposed mice or HFN-exposed mice. Immunohistochemical analysis showed a decreased number of vestibular hair cells and increased levels of oxidative stress in LFN-exposed mice compared to those in non-exposed mice. Our results suggest that chronic exposure to LFN at moderate levels causes impaired balance involving morphological impairments of the vestibule with enhanced levels of oxidative stress. Thus, the results of this study indicate the importance of considering the risk of chronic exposure to LFN at a moderate level for imbalance.