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At least 37 records · Page 2

The effects of heavy particle irradiation on exploration and response to environmental change

Free radicals produced by exposure to heavy particles have been found to produce motor and cognitive behavioral toxicity effects in rats similar to those found during aging. The present research was designed to investigate the effects of exposure to 56Fe particles on the ability of male Sprague-Dawley rats to detect novel arrangements in a given environment. Using a test of spatial memory previously demonstrated to be sensitive to aging, open field activity and reaction to spatial and non-spatial changes were measured in a group that received a dose of 1.5 Gy (n=10) of 56Fe heavy particle radiation or in non-radiated controls (n=10). Animals irradiated with 1.5 Gy of 56Fe particles exhibited some age-like effects in rats tested, even though they were, for the most part, subtle. Animals took longer to enter, visited less and spent significantly less time in the middle and the center portions of the open field, independently of total frequency and duration of activity of both groups. Likewise, irradiated subjects spend significantly more time exploring novel objects placed in the open field than did controls. However, irradiated subjects did not vary from controls in their exploration patterns when objects in the open field were spatially rearranged. Thus, irradiation with a dose of 1.5 Gy of 56Fe high-energy particle radiation elicited age-like effects in general open field exploratory behavior, but did not elicit age-like effects during the spatial and non-spatial rearrangement tasks. Published by Elsevier Ltd on behalf of COSPAR.

NASA Program Biomedical Research and Countermeasur↗

Daytime Cognitive Performance in Response to Sunlight or Fluorescent Light Controlling for Sleep Duration

Light is the primary synchronizer of the human circadian rhythm and also has acute alerting effects. Our study involves and comparing the alertness, performance and sleep of participants in the NASA Ames Sustainability Base, which uses sunlight as its primary light source, to in a traditional office building which uses overhead florescent lighting and varying exposure to natural light. The purpose of this study is to determine whether the use of natural lighting as a primary light source improves daytime cognitive function and promotes nighttime sleep. Participants from the Sustainability Base will be matched by gender and age to individuals working in other NASA buildings. In a prior study we found no differences in performance between those working in the Sustainability Base and those working in other buildings. Unexpectedly, we found that the average sleep duration among participants in both buildings was short, which likely obscured our ability to detect a difference the effect of light exposure on alertness. Given that such sleep deprivation has negative effects on cognitive performance, in this iteration of the study we are asking the participants to maintain a regular schedule with eight hours in bed each night in order to control for the effect of self-selected sleep restriction. Over the course of one week, we will ask the participants to wear actiwatches continuously, complete a psychomotor vigilance task (PVT) and digit symbol substitution task (DSST) three times per day, and keep daily sleepwork diaries. We hope that this study will provide data to support the idea that natural lighting and green architectural design are optimal to enhance healthy nighttime sleep patterns and daytime cognitive performance.

cognitive performance↗

Effects Of Five-Ion Galactic Cosmic Radiation Simulation On Immune Function, Brain, And Behavior In Male And Female Mice

Exposure to galactic cosmic radiation is a principal consideration of spaceflight missions, and with upcoming missions to the Moon and Mars, it is increasingly imperative to elucidate the effects of space travel beyond the lower Earth orbit. Additionally, with the first female astronaut to soon travel to the Moon there is a strong need to understand the biological sex differences to adaptation to the deep space environment. While the effects of spaceflight on the nervous system are not fully known, studies in animal models have shown that exposure to ionizing radiation can cause neuronal damage and lead to downstream cognitive and behavioral deficits. To simulate the type of radiation exposure occurring during spaceflight, model organisms can be exposed to relevant doses via Five-Ion Galactic Cosmic Radiation Simulation at the NASA National Space Radiation Laboratory at Brookhaven National Laboratory. We have investigated the neurobehavioral responses to space environment-like radiation exposure. Male and female 23–24-week-old mice (age-matched to average astronaut age) were exposed to 5, 15 and 50 cGy. Following exposure, immune, brain and behavioral (sensorimotor, risk-taking and cognitive) measures were acquired at ‘Acute’ (IR+24hrs, IR+72hrs), ‘Intermediate’ (IR+14 days) and ‘Delayed’ (IR+28 to IR+124 days) to inform biological responses anticipated during a transit to Moon and Mars. There were pronounced sex differences observed in all outcome measurements, while very few radiation induced effects were observed. Those dose effects that were observed were primarily in cytokine expression and less so in behavioral measurements. Further studies will investigate if radiation, microgravity and social isolation combine synergistically to trigger an oxidative stress response that alters immune homeostasis, brain structure/function, and neurobehavioral/cognitive performance, ultimately to characterize risks and identify appropriate countermeasures in both women and men in anticipation of future deep space missions.

Stephanie Puukila↗

Neurobehavioral Effects Of Five-Ion GCRSim Exposure In Male And Female Mice

Exposure to space galactic cosmic radiation is a principal consideration of spaceflight missions, and with upcoming missions to the Moon and Mars, it is increasingly imperative to elucidate the detrimental effects of space travel beyond the lower Earth orbit. Additionally, with the first female astronaut to soon travel to the Moon and beyond lower Earth orbit, there is a strong need to understand the biological sex differences to adaptation to the deep space environment. While the effects of spaceflight on the nervous system are not fully known, studies in animal models have shown that exposure to ionizing radiation can cause neuronal damage and lead to downstream cognitive and behavioral deficits. Therefore, we investigated the neurobehavioral responses to space environment-like radiation exposure. Male and female 23–24-week-old mice (age-matched to average astronaut age) were exposed to 5, 15 and 50 cGy via Five-Ion Galactic Cosmic Ray Simulation at the NASA National Space Radiation Laboratory at Brookhaven National Laboratory. Both early (72hrs post exposure) and late (1-4 months post exposure) cognitive and behavioral deficits were investigated. In-cage behavior was analyzed as frequency/duration of digging, rearing, and grooming and nestlet building using a 5-stage Deacon score. Additionally, at NASA Ames, behavior tests included Catwalk (gait), Zero Maze (anxiety), Adhesive Removal (sensory motor), Novel Object Recognition and Barnes Maze (working memory). There were pronounced sex differences in both early and late time points. Females typically performed the tests better than males, specifically in nestlet building, gait and working memory, though males performed better at the sensory motor (adhesive removal) test. Dose effects were primarily observed at 50 cGy for both sexes, particularly with the Barnes Maze (working memory), where both males and females exposed to 50 cGy showed little to no improvement in test performance, though females again performed better than males. Currently, we are investigating the correlations between the observed behavior and cytokine levels in the plasma and brain. Future studies will continue to investigate cognitive consequences of galactic cosmic radiation in combination with other space-like environment stressors, including antigravity and social versus single housing.

Stephanie Puukila↗

Early And Late Neurobehavioral Effects Of Male And Female Mice Exposed To Five-Ion GCRSim

With upcoming missions to the Moon and beyond to Mars, it is increasingly imperative to elucidate the detrimental effects of space travel beyond the lower Earth orbit, particularly to galactic cosmic radiation. Additionally, with the first female astronaut to soon travel to the Moon there is a strong need to understand the biological sex differences to adaptation to the deep space environment. While the effects of spaceflight on the nervous system are not fully known, studies in animal models have shown that exposure to ionizing radiation can cause neuronal damage and lead to downstream cognitive and behavioral deficits. Here, we investigated the neurobehavioral responses to space environment-like radiation exposure. Male and female 23–24-week-old mice (age-matched to average astronaut age) were exposed to 5, 15 and 50 cGy via Five-Ion Galactic Cosmic Ray Simulation at the NASA National Space Radiation Laboratory at Brookhaven National Laboratory. Both early (72hrs post exposure) and late (1-4 months post exposure) cognitive and behavioral deficits were investigated. Early analysis was performed by observing in-cage behavior including frequency/duration of digging, rearing, and grooming and nestlet building. Additionally, late effects were analyzed at NASA Ames via in-cage behavior as well as Catwalk (gait), Zero Maze (anxiety), Adhesive Removal (sensory motor), Novel Object Recognition and Barnes Maze (working memory). There were pronounced sex differences in both early and late time points. Females scored better than males in nestlet building, gait and working memory while males scored better at the sensory motor (adhesive removal) test. Dose effects were primarily observed at 50 cGy for both sexes, particularly with the Barnes Maze (working memory), where both males and females exposed to 50 cGy showed little to no improvement in test performance, though females again performed better than males. Currently, we are investigating the correlations between the observed behavior and cytokine levels in the plasma and brain. Future studies will continue to investigate cognitive consequences of galactic cosmic radiation in combination with other space-like environment stressors, including antigravity and social versus single housing.

S Puukila↗

Neurobehavioral Effects Of Five-Ion GCRSim Exposure In Male And Female Mice

Exposure to space galactic cosmic radiation is a principal consideration of spaceflight missions, and with upcoming missions to the Moon and Mars, it is increasingly imperative to elucidate the detrimental effects of space travel beyond the lower Earth orbit. Additionally, with the first female astronaut to soon travel to the Moon and beyond lower Earth orbit, there is a strong need to understand the biological sex differences to adaptation to the deep space environment. While the effects of spaceflight on the nervous system are not fully known, studies in animal models have shown that exposure to ionizing radiation can cause neuronal damage and lead to downstream cognitive and behavioral deficits. Therefore, we investigated the neurobehavioral responses to space environment-like radiation exposure. Male and female 23–24-week-old mice (age-matched to average astronaut age) were exposed to 5, 15 and 50 cGy via Five-Ion Galactic Cosmic Ray Simulation at the NASA National Space Radiation Laboratory at Brookhaven National Laboratory. Both early (72hrs post exposure) and late (1-4 months post exposure) cognitive and behavioral deficits were investigated. In-cage behavior was analyzed as frequency/duration of digging, rearing, and grooming and nestlet building using a 5-stage Deacon score. Additionally, at NASA Ames, behavior tests included Catwalk (gait), Zero Maze (anxiety), Adhesive Removal (sensory motor), Novel Object Recognition and Barnes Maze (working memory). There were pronounced sex differences in both early and late time points. Females typically performed the tests better than males, specifically in nestlet building, gait and working memory, though males performed better at the sensory motor (adhesive removal) test. Dose effects were primarily observed at 50 cGy for both sexes, particularly with the Barnes Maze (working memory), where both males and females exposed to 50 cGy showed little to no improvement in test performance, though females again performed better than males. Currently, we are investigating the correlations between the observed behavior and cytokine levels in the plasma and brain. Future studies will continue to investigate cognitive consequences of galactic cosmic radiation in combination with other space-like environment stressors, including antigravity and social versus single housing.

S. Puukila↗

Homocysteine and Cognitive Performance in Elders with Self-Neglect

Elevated plasma homocysteine has been associated with altered cognitive performance in older adults. Elders referred to Adult Protective Services (APS) for self-neglect have been reported to have elevated plasma homocysteine levels and to suffer from cognitive impairment. This study assesses the association, if any, between plasma homocysteine and cognitive performance among elders with self-neglect. Methods: Sixty-five community-living adults, 65 years of age and older, reported to Adult Protective Services for self-neglect and 55 matched controls (matched for age, ethnicity, gender and socio-economic status) consented and participated in this study. The research team conducted in-home comprehensive geriatric assessments which included the mini-mental state exam (MMSE), the 15-item geriatric depression scale (GDS), the Wolf-Klein Clock Drawing Tests (CDT) and a comprehensive nutritional biochemistry panel, which included plasma homocysteine. Student s t tests and Pearson correlations were conducted to assess for bivariate associations. Results: Elders with self-neglect had significantly higher plasma homocysteine levels (M=12.68umol/L, sd=4.4) compared to the controls (M=10.40umol/L, sd=3.61;t=3.21, df=127, p=.002). There were no statistically significant associations between cognitive performance and plasma homocysteine in the self-neglect group, however there was a significant correlation between plasma homocysteine and the CDT among the controls (r=-.296, p=.022). Conclusion: Mean plasma homocysteine levels were significantly higher in elders with self-neglect, however, they do not appear to be related to cognitive performance, indicating that cognitive impairment in elder self-neglect involve mechanisms other than hyperhomocysteinemia. These findings warrant further investigation

Burnett, J.↗

Preliminary Results Obtained in Integrated Safety Analysis of NASA Aviation Safety Program Technologies

This is a listing of recent unclassified RTO technical publications processed by the NASA Center for AeroSpace Information from January 1, 2001 through March 31, 2001 available on the NASA Aeronautics and Space Database. Contents include 1) Cognitive Task Analysis; 2) RTO Educational Notes; 3) The Capability of Virtual Reality to Meet Military Requirements; 4) Aging Engines, Avionics, Subsystems and Helicopters; 5) RTO Meeting Proceedings; 6) RTO Technical Reports; 7) Low Grazing Angle Clutter...; 8) Verification and Validation Data for Computational Unsteady Aerodynamics; 9) Space Observation Technology; 10) The Human Factor in System Reliability...; 11) Flight Control Design...; 12) Commercial Off-the-Shelf Products in Defense Applications.

Source record↗

Later endogenous circadian temperature nadir relative to an earlier wake time in older people

The contribution of the circadian timing system to the age-related advance of sleep-wake timing was investigated in two experiments. In a constant routine protocol, we found that the average wake time and endogenous circadian phase of 44 older subjects were earlier than that of 101 young men. However, the earlier circadian phase of the older subjects actually occurred later relative to their habitual wake time than it did in young men. These results indicate that an age-related advance of circadian phase cannot fully account for the high prevalence of early morning awakening in healthy older people. In a second study, 13 older subjects and 10 young men were scheduled to a 28-h day, such that they were scheduled to sleep at many circadian phases. Self-reported awakening from scheduled sleep episodes and cognitive throughput during the second half of the wake episode varied markedly as a function of circadian phase in both groups. The rising phase of both rhythms was advanced in the older subjects, suggesting an age-related change in the circadian regulation of sleep-wake propensity. We hypothesize that under entrained conditions, these age-related changes in the relationship between circadian phase and wake time are likely associated with self-selected light exposure at an earlier circadian phase. This earlier exposure to light could account for the earlier clock hour to which the endogenous circadian pacemaker is entrained in older people and thereby further increase their propensity to awaken at an even earlier time.

NASA Discipline Regulatory Physiology↗

Development of intuitive theories of motion - Curvilinear motion in the absence of external forces

College students and children between the ages of 4 and 12 were asked to draw the path a ball would take upon exiting a curved tube. As in previous studies, many subjects erroneously predicted curvilinear paths. However, a clear U-shaped curve was evident in the data: Preschoolers and kindergartners performed as well as college students, whereas school-aged children were more likely to make erroneous predictions. A second study suggested that the youngest children's correct responses could not be attributed to response biases or drawing abilities. This developmental trend is interpreted to mean that the school-aged children are developing intuitive theories of motion that include erroneous principles. The results are related to the 'growth errors' found in other cognitive domains and to the historical development of formal theories of motion.

Kaiser, M. K.↗

Oxidative Stress and the Neuroconsequences of Spaceflight Environment - Immune Dysregulation and Antioxidant Dietary Countermeasure Efficacy

In this project, we will test the hypothesis that Ionizing Radiation (IR), microgravity and social isolation combine synergistically to trigger an oxidative stress response that alters immune homeostasis, brain structure and function, and neurobehavioral and cognitive performance. Specific Aims for this project are: (1) Determine dose-response curves for acute ‘Five-Ion GCR Simulation’ exposure for immune, brain and performance responses in crew age-matched adult male and female mice; (2) Determine effects of acute ‘Five-Ion GCR Simulation’ exposure singly and in combination with simulated microgravity and social isolation, on immune, brain and performance responses in crew age-matched male and female mice mimicking deep space missions; and (3) Determine efficacy of the dietary antioxidant, Nicotinamide Mononucleotide (NMN), a key intermediate in nicotinamide adenine dinucleotide (NAD+) biosynthesis. The project relies on established and highly translatable ground-based mouse models and assays with IR exposures to be performed at the NASA Space Radiation Laboratory (NSRL). The experimental approach will provide definitive data on the timing and mechanisms involved in the oxidative stress response, immune and brain changes, and ensuing functional (behavioral/cognitive) impairments expected during human transit to Mars. This project will identify potential biomarkers for, and mechanisms underlying, structural and functional changes in the immune and nervous systems leading to behavioral/cognitive performance deficits, and its potential application to develop effective countermeasures to mitigate negative health effects of long duration space habitation. The project will address NASA’s efforts to rapidly advance the characterization of risks and identify appropriate countermeasures in anticipation of future deep space missions. Ensuring crew health and performance during extended transits necessitates that sensorimotor and cognitive abilities remain strong to avoid potentially catastrophic health and safety outcomes. Further, despite historically low numbers of female astronauts, the two most recent NASA Astronaut Corps class selections, comprised of ~50% women as compared to men, signal the need to understand how sex differences affect physiological adaptation and health in the space environment. Here, we will determine how key features of the deep space environment may interact to increase risk to crewmembers by negatively impacting health and performance, and identify and develop strategies to characterize and mitigate the potential risks via countermeasures. Supported by the NASA Human Research Program (HRP) Human Factors Behavioral Performance Element Grant 18-18FLAG_2-0028.

radiation↗

Effects of Acute Exposures to Carbon Dioxide upon Cognitive Functions

Carbon dioxide (CO2) originates from human metabolism and typically remains about 10-fold higher in concentration on the International Space Station (ISS) than at the earth's surface. There have been recurring complaints by crew members of episodes of "mental viscosity" adversely affecting their performance, and there is evidence from the ISS that associates CO2 levels with reports of headaches by crewmembers. Consequently, flight rules have been employed to control CO2 below 3 mm Hg, which is well below the existing Spacecraft Maximum Allowable Concentration (SMAC) of 10 mm Hg for 24-hour exposures, and 5.3 mm Hg for exposures of 7 to 180 days. Headaches, while sometime debilitating themselves, are also symptoms that can provide evidence that physiological defense mechanisms have been breached, and there is evidence that CO2 has effects at levels below the threshold for headaches. This concern appears to be substantiated in reports that CO2 at concentrations below 2 mm Hg substantially reduced some cognitive functions that are associated with the ability to make complex decisions in conditions that are characterized by volatility, uncertainty, complexity, ambiguity, and delayed feedback. These are conditions that could be encountered by crews in off-nominal situations or during the first missions beyond low earth orbit. Therefore, we set out to determine if decision-making under volatile, uncertain, confusing and ambiguous circumstances, where feedback is delayed or absent, is correlated with low levels of CO2 during acute exposures (several hours) in crew-like subjects and to determine if additional cognitive domains are sensitive to concentrations of CO2 at, or below, current ISS levels by using a test battery that is currently available onboard ISS. We enrolled 22 volunteers (8 females, 14 males) between the ages of 30-55 (38.8 +/- 7.0) years whose training and professional experience reflect that of the astronaut corps. Subjects were divided among 4 study groups. Exposures occurred in the 20-foot environmental chamber in Bldg 7 at JSC. Each group was exposed to each of four concentrations of CO2 (600, 1200, 2500, and 5000 ppm), and the exposure order was balanced across the groups which were randomly assigned to 4 possible complete exposure orders. Study participants and investigators were blinded to the exposure order. Each exposure lasted 4 hours and occurred on the same day each week for 4 consecutive weeks. Testing included the Strategic Management Simulation (SMS) methodology and the Cognition battery of psychometric measures that are being utilized aboard the ISS. Subjects participated in a familiarization session one week prior to the start of exposure sessions. Each exposure session followed the schedule noted in Figure 1 below. On the morning of each exposure, subjects completed the Cognition battery in a conference room at indoor ambient CO2 levels. Subjects then entered the exposure chamber and were acclimated to the environment for 15 minutes before completing another round of the Cognition battery. After a 20 minute rest, subject completed the approx.80 minute SMS. Subjects were allowed another 20 minute rest period before completing the final Cognition test battery in the exposure chamber. Subjects then returned to the conference room where they completed one final round of Cognition. Data from both testing methodologies are currently being analyzed and will be presented. Study investigators have not yet been unblinded to the coded exposure concentrations, but preliminary results suggest differences.

Ryder, V. E.↗

Evidence Report: Risk of Acute and Late Central Nervous System Effects from Radiation Exposure

Possible acute and late risks to the central nervous system (CNS) from galactic cosmic rays (GCR) and solar particle events (SPE) are a documented concern for human exploration of space. Acute CNS risks include: altered cognitive function, reduced motor function, and behavioral changes, all of which may affect performance and human health. Late CNS risks include neurological disorders such as Alzheimer's disease (AD), dementia and premature aging. Although detrimental CNS changes are observed in humans treated with high-dose radiation (e.g., gamma rays and protons) for cancer and are supported by experimental evidence showing neurocognitive and behavioral effects in animal models, the significance of these results on the morbidity to astronauts has not been elucidated. There is a lack of human epidemiology data on which to base CNS risk estimates; therefore, risk projection based on scaling to human data, as done for cancer risk, is not possible for CNS risks. Research specific to the spaceflight environment using animal and cell models must be compiled to quantify the magnitude of CNS changes in order to estimate this risk and to establish validity of the current permissible exposure limits (PELs). In addition, the impact of radiation exposure in combination with individual sensitivity or other space flight factors, as well as assessment of the need for biological/pharmaceutical countermeasures, will be considered after further definition of CNS risk occurs.

Nelson, Gregory A.↗

Evidence Report: Risk of Acute and Late Central Nervous System Effects from Radiation Exposure

Possible acute and late risks to the central nervous system (CNS) from galactic cosmic rays (GCR) and solar particle events (SPE) are concerns for human exploration of space. Acute CNS risks may include: altered cognitive function, reduced motor function, and behavioral changes, all of which may affect performance and human health. Late CNS risks may include neurological disorders such as Alzheimer's disease (AD), dementia and premature aging. Although detrimental CNS changes are observed in humans treated with high-dose radiation (e.g., gamma rays and 9 protons) for cancer and are supported by experimental evidence showing neurocognitive and behavioral effects in animal models, the significance of these results on the morbidity to astronauts has not been elucidated. There is a lack of human epidemiology data on which to base CNS risk estimates; therefore, risk projection based on scaling to human data, as done for cancer risk, is not possible for CNS risks. Research specific to the spaceflight environment using animal and cell models must be compiled to quantify the magnitude of CNS changes in order to estimate this risk and to establish validity of the current permissible exposure limits (PELs). In addition, the impact of radiation exposure in combination with individual sensitivity or other space flight factors, as well as assessment of the need for biological/pharmaceutical countermeasures, will be considered after further definition of CNS risk occurs.

Nelson, Gregory A.↗

Brain signaling and behavioral responses induced by exposure to (56)Fe-particle radiation

Previous experiments have demonstrated that exposure to 56Fe-particle irradiation (1.5 Gy, 1 GeV) produced aging-like accelerations in neuronal and behavioral deficits. Astronauts on long-term space flights will be exposed to similar heavy-particle radiations that might have similar deleterious effects on neuronal signaling and cognitive behavior. Therefore, the present study evaluated whether radiation-induced spatial learning and memory behavioral deficits are associated with region-specific brain signaling deficits by measuring signaling molecules previously found to be essential for behavior [pre-synaptic vesicle proteins, synaptobrevin and synaptophysin, and protein kinases, calcium-dependent PRKCs (also known as PKCs) and PRKA (PRKA RIIbeta)]. The results demonstrated a significant radiation-induced increase in reference memory errors. The increases in reference memory errors were significantly negatively correlated with striatal synaptobrevin and frontal cortical synaptophysin expression. Both synaptophysin and synaptobrevin are synaptic vesicle proteins that are important in cognition. Striatal PRKA, a memory signaling molecule, was also significantly negatively correlated with reference memory errors. Overall, our findings suggest that radiation-induced pre-synaptic facilitation may contribute to some previously reported radiation-induced decrease in striatal dopamine release and for the disruption of the central dopaminergic system integrity and dopamine-mediated behavior.

NASA Discipline Radiation Health↗

Arctic cognition: a study of cognitive performance in summer and winter at 69 degrees N

Evidence has accumulated over the past 15 years that affect in humans is cyclical. In winter there is a tendency to depression, with remission in summer, and this effect is stronger at higher latitudes. In order to determine whether human cognition is similarly rhythmical, this study investigated the cognitive processes of 100 participants living at 69 degrees N. Participants were tested in summer and winter on a range of cognitive tasks, including verbal memory, attention and simple reaction time tasks. The seasonally counterbalanced design and the very northerly latitude of this study provide optimal conditions for detecting impaired cognitive performance in winter, and the conclusion is negative: of five tasks with seasonal effects, four had disadvantages in summer. Like the menstrual cycle, the circannual cycle appears to influence mood but not cognition.

Cognition↗

Working and strategic memory deficits in schizophrenia

Working memory and its contribution to performance on strategic memory tests in schizophrenia were studied. Patients (n = 18) and control participants (n = 15), all men, received tests of immediate memory (forward digit span), working memory (listening, computation, and backward digit span), and long-term strategic (free recall, temporal order, and self-ordered pointing) and nonstrategic (recognition) memory. Schizophrenia patients performed worse on all tests. Education, verbal intelligence, and immediate memory capacity did not account for deficits in working memory in schizophrenia patients. Reduced working memory capacity accounted for group differences in strategic memory but not in recognition memory. Working memory impairment may be central to the profile of impaired cognitive performance in schizophrenia and is consistent with hypothesized frontal lobe dysfunction associated with this disease. Additional medial-temporal dysfunction may account for the recognition memory deficit.

Memory Disorders/etiology/physiopathology↗

The Effects of Blood Glucose Levels on Cognitive Performance: A Review of the Literature

The purpose of this review paper is to discuss the research literature on the effects of blood glucose levels on executive and non-executive functions in humans. The review begins with a brief description of blood glucose, how it has been studied, previous syntheses of prior studies, and basic results regarding the role of blood glucose on cognitive functioning. The following sections describe work that investigated the effect of blood glucose on both non-executive and executive functions (e.g., sensory processing, psychomotor functioning, attention, vigilance, memory, language and communication, judgement and decision-making, and complex task performance). Within each section, summaries of the findings and challenges to the literature are included. Measurement conversions of blood glucose levels, blood glucose values, and associated symptoms are depicted. References to the types of tests used to investigate blood glucose and cognitive performance are provided. For more detailed descriptions of references within (and in addition to) this paper, an annotated bibliography is also provided. Several moderator variables including individual differences and contextual variables related to the effects of blood glucose levels on performance (e.g., age, gender, time of day, familiarity with the task and symptom awareness, expectancy effects, dose dependent effects, time dependent effects, task specific effects, rising and falling blood glucose levels, and speed and/or accuracy trade-offs) are addressed later in the paper. Some suggestions for future experimental methodologies are also made.

Feldman, Jolene↗