Are attentional resources a mediator for sex differences in memory?

Physiological and Cognitive Determinants of Dual-Task Costs for Gait Parameters: The Yishun Study

BACKGROUND

Studies indicate that physiological and cognitive aging are causally related and functionally interdependent. However, the relative contribution of physiological factors and cognition to dual-task costs (DTC) of gait parameters has not been well studied. In this cross-sectional study, we examined the trajectory of DTC of gait parameters across the adult age spectrum for both sexes and identified the contributions of physical and cognitive performance to DTC of gait.

METHODS

A total of 492 community-dwelling adults, aged 21-90 years, were randomly recruited into the study. Participants were divided into 7 age groups, with 10-year age range for each group. Demographic data, height, body mass, education level, and information on comorbidities were recorded. Cognition was measured using the Repeatable Battery for the Assessment of Neuropsychological Status. Physical performance included visual contrast sensitivity, postural sway, hand reaction time, handgrip strength, knee extensor strength, and single-task and dual-task gait assessments. Stepwise multivariable regression was used to examine the association between physical and cognitive performance with DTC of gait parameters.

RESULTS

Women were found to have significantly higher DTC of gait speed (p = 0.01), cadence (p < 0.01), and double support time (p < 0.01) than men. However, significant aging effect on DTC of gait speed (p = 0.01), step length (p = 0.01), and double support time (p = 0.01) was observed in men but not in women. Immediate memory was the primary determinant for the DTC of gait speed (β = -0.25, p < 0.01), step length (β = -0.22, p < 0.01), and cadence (β = -0.15, p = 0.03) in men. Besides immediate memory, postural sway (β = -0.13, p = 0.03) and hand reaction (β = 0.14, p = 0.02) were also significantly associated with DTC of step length and cadence, respectively, in women.

CONCLUSION

There were sex differences in the amplitude and trajectories of DTC of gait parameters. The DTC increased with age in men but not in women. Immediate memory was the primary determinant of DTC of gait parameters in men while immediate memory, postural sway, and reaction time were associated with DTC of gait in women. Future studies should investigate the clinical implications of the sex differences in the DTC with fall risks.

An Examination of Study Time Allocation as a Contributor to Sex Differences in Multitrial Verbal Learning Performance

Researchers have noted sex differences in verbal memory performance with females showing a memory superiority effect. Research paradigms have largely incorporated experimenter-timed materials. Therefore, the extent to which self-regulating study time influences this pattern of sex differences is unclear. The researcher reexamined data from a published paper to determine whether sex differences in multitrial verbal learning are minimized when individuals self-regulate their study time, or if sex differences would still remain. The results from this study showed that females outperformed males on subsequent test trials, and they allocated more study time. Controlling for the influence of study time allocation reduced or eliminated sex differences in memory performance, and only study time allocation was related to whether items were gained or lost across trials. These findings suggest the importance of self-regulated learning in reducing sex differences on a verbal memory task and the contribution of study time allocation to memory performance.

Cholinergic Signaling Dynamics and Cognitive Control of Attention

The central cholinergic system is one of the most important modulator neurotransmitter system implicated in diverse behavioral processes. Activation of the basal forebrain cortical cholinergic input system represents a critical step in cortical information processing. This chapter explores recent developments illustrating cortical cholinergic transmission mediate defined cognitive operations, which is contrary to the traditional view that acetylcholine acts as a slowly acting neuromodulator that influences arousal cortex-wide. Specifically, we review the evidence that phasic cholinergic signaling in the prefrontal cortex is a causal mediator of signal detection. In addition, studies that support the neuromodulatory role of cholinergic inputs in top-down attentional control are summarized. Finally, we review new findings that reveal sex differences and hormonal regulation of the cholinergic-attention system.

Effects of attention during encoding on sex differences in object location memory

Attention plays a key role in memory processes and has been widely studied in various memory tasks. The role of attention in sex differences in object location memory is not clearly understood. In the present study, two experiments involving 186 participants and using an object array presented on paper were conducted to examine two encoding conditions: incidental and intentional. In each experiment, the participants were randomly assigned to divided versus full attention conditions. In the first experiment, which involved incidental encoding, women outperformed men in memorising location-exchanged objects in both the full and in the divided attention condition. In the second experiment, which involved intentional encoding, women outperformed men in memorising location-exchanged objects in the full attention condition, but not the divided attention condition. These findings deepen our knowledge regarding the role of attention in object location memory, specifically in terms of the conditions under which females have an advantage for detecting changes in an array of objects.

Sex differences in interval timing and attention to time in C57Bl/6J mice

Interval timing is crucial for decision-making and motor control and is impaired in many neuropsychiatric disorders. Previous studies examined timing in various strains or genetically-altered mice, but not in parallel in male and female mice in the same experimental setting. We investigated timing and attention to time in male and female C57Bl/6J mice, when presented with gaps in the timed stimulus, novel auditory distracters presented during the un-interrupted timed stimulus, and gap+distracter combinations. No sex differences were found in regard to timing accuracy and precision. However, presentation of the gap+distracter combination over-reset timing in males but had a much smaller effect in females. The over-reset strategy was reported previously with emotional distracters (e.g., previously paired with footshock) but not with neutral distracters. These results reveal sex differences in attentional gating/switching or working memory for time.

The role of attentional resources in explaining sex differences in object location memory

Sex differences in object location memory have been widely studied, with mixed results. The role of attention in mediating the female advantage in object location memory has not been clearly understood yet. Two experiments, involving 181 participants and using an actual object array, were conducted in the present study to examine two learning conditions: incidental and intentional. In each experiment, participants were randomly assigned to divided versus full attention conditions. The study also examined memorizing location-maintained and location-exchanged objects. In both experiments, in both incidental and intentional learning conditions, women outperformed men in memorizing location-exchanged objects in the full but not in the divided attention condition. These findings confirm and extend previous ones concerning the conditions under which the female advantage in the detection of change in an array of objects occurs. The findings are discussed within an evolutionary conceptual framework.