Traditional neuropsychological measurement of cognitive processing speed with tasks such as the Symbol Search and Coding subsets of the WAIS-IV consistently shows decline with advanced age. This is potentially problematic when these measures are employed with populations where deficits in motor performance are expected, i.e., in ageing or stroke populations. Thus, the aim of the current study was to explore the contribution of hand motor speed to traditional paper-and-pencil measures of processing speed and to a simple computer-customized non-motor perception decision task, the Inspection Time (IT) task. Participants were 67 young university students aged between 18 and 29 (59 females), and 40 older adults aged between 40 and 81 (31 females) primarily with a similar education profile. As expected, results indicated that age group differences were highly significant on the motor dexterity, Symbol Search and Coding tasks. However, no significant differences or correlations were seen between age groups and the simple visual perception IT task. Furthermore, controlling for motor dexterity did not remove significant age-group differences on the paper-and-pencil measures. This demonstrates that although much of past research into cognitive decline with age is confounded by use of motor reaction times as the operational measure, significant age differences in cognitive processing also exist on more complex tasks. The implications of the results are crucial in the realm of aging research, and caution against the use of traditional WAIS tasks with a clinical population where motor speed may be compromised, as in stroke.

Many diverse retinal disorders are characterized by retinal edema; yet, little experimental attention has been given to understanding the fundamental mechanisms underlying and contributing to these fluid-based disorders. Water transport in and out of cells is achieved by specialized membrane channels, with most rapid water transport regulated by transmembrane water channels known as aquaporins (AQPs). The predominant AQP in the mammalian retina is AQP4, which is expressed on the Müller glial cells. Müller cells have previously been shown to modulate neuronal activity by modifying the concentrations of ions, neurotransmitters, and other neuroactive substances within the extracellular space between the inner and the outer limiting membrane. In doing so, Müller cells maintain extracellular homeostasis, especially with regard to the spatial buffering of extracellular potassium (K⁺) via inward rectifying K⁺ channels (Kir channels). Recent studies of water transport and the spatial buffering of K⁺ through glial cells have highlighted the involvement of both AQP4 and Kir channels in regulating the extracellular environment in the brain and retina. As both glial functions are associated with neuronal activation, controversy exists in the literature as to whether the relationship is functionally dependent. It is argued in this review that as AQP4 channels are likely to be the conduit for facilitating fluid homeostasis in the inner retina during light activation, AQP4 channels are also likely to play a consequent role in the regulation of ocular volume and growth. Recent research has already shown that the level of AQP4 expression is associated with environmentally driven manipulations of light activity on the retina and the development of myopia.

Decline in information processing with age is well-documented in the scientific literature. However, some discrepancy remains in relation to which cognitive domains are most susceptible to the aging process and which may remain intact. Furthermore, information processing has not been investigated nor considered as a function of affect, familiarity and complexity of tasks in a single experimental study. Thus, the current study investigated rate of visual information processing in 67 young university students (M age = 19.64 years) and 33 educated healthy older adults (M age = 70.33 years), while accounting for depression, anxiety and stress symptoms using the DASS. Rates of visual processing were measured as minimum time of stimulus exposure duration required for correct object recognition on a simple visual task [Inspection Time (IT)], and on a more complex visual cognitive task known as Change Detection (CD)] as well as words per minute on a text reading task (FastaReada). The results demonstrated significantly slower performance by older adults on the IT and CD, but comparable rates of text reading on a semantically more complex, but ecologically valid and familiar visual task that requires organized sequential shifts in attention via eye movements, continuous visual processing, access to working memory and semantic comprehension. The results also demonstrated that affective influences did not play a role in the older adults task performance, and that changes in cognitive domains may begin with older adults being slower to attend to and identify newly appearing familiar objects, as well as slower to encode and embed new information in memory during tasks that require a less practiced/familiar task strategy.

The Maastricht Acute Stress Test (MAST) is designed to be a simple, quick, and non-invasive procedure aimed at activating the human stress system. The MAST has been developed by combining elements from two of the most common experimental paradigms measuring stress, the Trier Social Stress Test (TSST) and the Cold Pressor Test (CPT). The aim of this study was to use the MAST procedure to elicit strong autonomic and subjective stress responses that can be quantified in terms of (systolic and diastolic) blood pressure, pulse rate, and state anxiety ratings. In healthy individuals, the MAST induced a significant elevation of systolic blood pressure (SBP) from baseline for up to 30 minutes post-MAST, while diastolic blood pressure (DBP) dropped to baseline within 10 minutes post-MAST. Interestingly, the presentation of instructions alerting participants to the procedure resulted in significant elevation of both SBP and DBP above baseline. However, BP measurements prior to test initiation were not as high as those measured immediately after the MAST procedure. Pulse rate data showed limited variability across time points. Self-reported state anxiety increased dramatically from baseline to immediately following the MAST procedure. Further, individuals who reported higher levels of depression and stress were more likely to demonstrate larger increases in SBP in response to the MAST. Together these results support the use of the MAST as a useful tool to activate both acute physiological and subjective measures of the stress response in healthy adults lasting up to 30 minutes.