Neurotoxic effects of home radon exposure on oscillatory dynamics serving attentional orienting in children and adolescents.

Radon is a naturally occurring gas that contributes significantly to radiation in the environment and is the second leading cause of lung cancer globally. Previous studies have shown that other environmental toxins have deleterious effects on brain development, though radon has not been studied as thoroughly in this context. This study examined the impact of home radon exposure on the neural oscillatory activity serving attention reorientation in youths. Fifty-six participants (ages 6-14 years) completed a classic Posner cuing task during magnetoencephalography (MEG), and home radon levels were measured for each participant. Time-frequency spectrograms indicated stronger theta (3-7 Hz, 300-800 ms), alpha (9-13 Hz, 400-900 ms), and beta responses (14-24 Hz, 400-900 ms) during the task relative to baseline. Source reconstruction of each significant oscillatory response was performed, and validity maps were computed by subtracting the task conditions (invalidly cued - validly cued). These validity maps were examined for associations with radon exposure, age, and their interaction in a linear regression design. Children with greater radon exposure showed aberrant oscillatory activity across distributed regions critical for attentional processing and attention reorientation (e.g., dorsolateral prefrontal cortex, and anterior cingulate cortex). Generally, youths with greater radon exposure exhibited a reverse neural validity effect in almost all regions and showed greater overall power relative to peers with lesser radon exposure. We also detected an interactive effect between radon exposure and age where youths with greater radon exposure exhibited divergent developmental trajectories in neural substrates implicated in attentional processing (e.g., bilateral prefrontal cortices, superior temporal gyri, and inferior parietal lobules). These data suggest aberrant, but potentially compensatory neural processing as a function of increasing home radon exposure in areas critical for attention and higher order cognition.

Effects of bright light and an afternoon nap on task performance depend on the cognitive domain.

Previous research revealed inconsistent effects of bright light or a short nap at noon on alertness and performance across different tasks. The current study aimed to explore whether the effects of bright light and a short nap at noon on task performance depended on the cognitive domain. Bright light (1,200 lx, 4,000 K at eye level), nap (near darkness) and control (200 lx, 4,000 K at eye level) conditions were performed from 1:00 to 1:40 PM on three non-consecutive days with a counterbalanced order across participants. After being assigned to one of three conditions, participants underwent two repeated test sessions, each including a psychomotor vigilance task, a go/no-go task, and a paced visual serial addition task, with an interval of more than 1 h, to assess the persistent effects of napping and bright light. Subjective sleepiness, vitality, self-control and mood were also measured. Results showed that accuracy on the go/no-go task and the paced visual serial addition task improved significantly throughout the entire experiment session after napping, whereas reaction speed on the paced visual serial addition task improved time-dependently in the bright light intervention, with a higher reaction speed in only the first test session. Nearly all subjective states benefited from napping but not from bright light. These findings suggested that the effects of bright light and an afternoon nap on task performance would depend on the cognitive domain. An afternoon nap may elicit more effective and persistent benefits on task performance and subjective states.

Coordination Cost and Super-Efficiency in Teamwork: The Role of Communication, Psychological States, Cardiovascular Responses, and Brain Rhythms.

To advance knowledge on the psychophysiological markers of "coordination cost" in team settings, we explored differences in meta-communication patterns (i.e., silence, speaking, listening, and overlap), perceived psychological states (i.e., core affect, attention, efficacy beliefs), heart rate variability (i.e., RMSSD), and brain rhythms (i.e., alpha, beta and theta absolute power) across three studies involving 48 male dyads (Mage = 21.30; SD = 2.03). Skilled participants cooperatively played three consecutive FIFA-17 (Xbox) games in a dyad against the computer, or competed against the computer in a solo condition and a dyad condition. We observed that playing in a team, in contrast to playing alone, was associated with higher alpha peak and global efficiency in the brain and, at the same time, led to an increase in focused attention as evidenced by participants' higher theta activity in the frontal lobe. Moreover, we observed that overtime participants' brain dynamics moved towards a state of "neural-efficiency", characterized by increased theta and beta activity in the frontal lobe, and high alpha activity across the whole brain. Our findings advance the literature by demonstrating that (1) the notion of coordination cost can be captured at the neural level in the initial stages of team development; (2) by decreasing the costs of switching between tasks, teamwork increases both individuals' attentional focus and global neural efficiency; and (3) communication dynamics become more proficient and individuals' brain patterns change towards neural efficiency over time, likely due to team learning and decreases in intra-team conflict.

Photobiomodulation improves the frontal cognitive function of older adults.

OBJECTIVES: The frontal lobe hypothesis of age-related cognitive decline suggests that the deterioration of the prefrontal cortical regions that occurs with aging leads to executive function deficits. Photobiomodulation (PBM) is a newly developed, noninvasive technique for enhancing brain function, which has shown promising effects on cognitive function in both animals and humans. This randomized, sham-controlled study sought to examine the effects of PBM on the frontal brain function of older adults. METHODS/DESIGNS: Thirty older adults without a neuropsychiatric history performed cognitive tests of frontal function (ie, the Eriksen flanker and category fluency tests) before and after a single 7.5-minute session of real or sham PBM. The PBM device consisted of three separate light-emitting diode cluster heads (633 and 870 nm), which were applied to both sides of the forehead and posterior midline, and delivered a total energy of 1349 J. RESULTS: Significant group (experimental, control) × time (pre-PBM, post-PBM) interactions were found for the flanker and category fluency test scores. Specifically, only the older adults who received real PBM exhibited significant improvements in their action selection, inhibition ability, and mental flexibility after vs before PBM. CONCLUSIONS: Our findings support that PBM may enhance the frontal brain functions of older adults in a safe and cost-effective manner.

Sensory-Biased and Multiple-Demand Processing in Human Lateral Frontal Cortex.

The functionality of much of human lateral frontal cortex (LFC) has been characterized as "multiple demand" (MD) as these regions appear to support a broad range of cognitive tasks. In contrast to this domain-general account, recent evidence indicates that portions of LFC are consistently selective for sensory modality. Michalka et al. (2015) reported two bilateral regions that are biased for visual attention, superior precentral sulcus (sPCS) and inferior precentral sulcus (iPCS), interleaved with two bilateral regions that are biased for auditory attention, transverse gyrus intersecting precentral sulcus (tgPCS) and caudal inferior frontal sulcus (cIFS). In the present study, we use fMRI to examine both the multiple-demand and sensory-bias hypotheses within caudal portions of human LFC (both men and women participated). Using visual and auditory 2-back tasks, we replicate the finding of two bilateral visual-biased and two bilateral auditory-biased LFC regions, corresponding to sPCS and iPCS and to tgPCS and cIFS, and demonstrate high within-subject reliability of these regions over time and across tasks. In addition, we assess MD responsiveness using BOLD signal recruitment and multi-task activation indices. In both, we find that the two visual-biased regions, sPCS and iPCS, exhibit stronger MD responsiveness than do the auditory-biased LFC regions, tgPCS and cIFS; however, neither reaches the degree of MD responsiveness exhibited by dorsal anterior cingulate/presupplemental motor area or by anterior insula. These results reconcile two competing views of LFC by demonstrating the coexistence of sensory specialization and MD functionality, especially in visual-biased LFC structures.SIGNIFICANCE STATEMENT Lateral frontal cortex (LFC) is known to play a number of critical roles in supporting human cognition; however, the functional organization of LFC remains controversial. The "multiple demand" (MD) hypothesis suggests that LFC regions provide domain-general support for cognition. Recent evidence challenges the MD view by demonstrating that a preference for sensory modality, vision or audition, defines four discrete LFC regions. Here, the sensory-biased LFC results are reproduced using a new task, and MD responsiveness of these regions is tested. The two visual-biased regions exhibit MD behavior, whereas the auditory-biased regions have no more than weak MD responses. These findings help to reconcile two competing views of LFC functional organization.

Acute effects of the electromagnetic waves emitted by mobile phones on attention in emergency physicians.

STUDY OBJECTIVE: The purpose of this study was to investigate the acute effects of the electromagnetic waves (EMW) emitted by mobile phones on attention in emergency physicians. METHODS: This single-center, prospective, randomized, double-blinded clinical study was performed among emergency physicians in a tertiary hospital. Thirty emergency physicians were enrolled in the study. Initial d2 test was applied in the evaluation of attention and concentration of all the physicians, who were randomly assigned into one of two groups. The control group members hold mobile phones in 'off' mode to their left ears for 15min. The members of the intervention group hold mobile phones in 'on' mode to their left ears for 15min, thus exposing them to 900-1800MHz EMW. The d2 test was re-applied to both groups after this procedure. Differences in attention and concentration levels between the groups were compared. RESULTS: Difference between initial and final d2 test in total performance (TN-E, p=0.319), in total number of figures marked (TN, p=0.177), in test performance percentile (PR, p=0.619) and in attention fluctuation (FR, p=0.083) were similar between the groups. However, difference in the number of figures missed (E1 selective attention, p=0.025), difference between numbers of incorrectly marked figures (E2, p=0,018) and difference in focus levels (E, p=0.016) were significantly in favor of the intervention group. CONCLUSION: According to our study findings, the EMW emitted by mobile phones has no deleterious effect on the attention and concentration levels of emergency physicians, and even has a positive impact on selective attention levels.

Effects of very high-frequency sound and ultrasound on humans. Part II: A double-blind randomized provocation study of inaudible 20-kHz ultrasound.

Some people have reported symptoms such as nausea, dizziness, and headaches that they attribute to ultrasound (US) emitted by devices in public places. The primary aim of the present study was to investigate whether inaudible US can provoke adverse symptoms compared to a sham presentation, under double-blind conditions. A second aim was to investigate whether the expectation of US being present could provoke adverse symptoms (a nocebo response). The US stimulus was a 20 kHz tone presented continuously for 20 min set to at least 15 dB below the participants' detection threshold, giving a typical sound pressure level (SPL) of 84 dB. No evidence that US provoked symptoms was found, but there was evidence of small nocebo effects. A case study on an individual with high self-reported sensitivity to US gave similar results. The present study did not reproduce the severe symptoms reported previously by some members of the public; this may be due to the SPL or duration of the stimulus, or strength of the nocebo stimulus. These findings cannot be used to predict outcomes from exposures to sounds that are audible to the individual in question, or to sounds with higher SPLs, longer durations, or different frequency content.

Effects of very high-frequency sound and ultrasound on humans. Part I: Adverse symptoms after exposure to audible very-high frequency sound.

Various adverse symptoms resulting from exposure to very high-frequency sound (VHFS) and ultrasound (US) have previously been reported. This study aimed to establish whether these symptoms are experienced under controlled laboratory conditions and are specific to VHFS/US. To do this, participants were exposed to VHFS/US (at frequencies between 13.5 and 20 kHz and sound pressure levels between 82 and 92 dB) and to a 1 kHz reference stimulus, both at 25 dB above their hearing threshold. The VHFS/US and reference stimuli were presented 4 times, each time for 3 min, during which participants performed a sustained attention task, rated their symptom severity, and had their galvanic skin response (GSR) measured to assess their level of anxiety. Prior to exposure, participants were assigned either to a symptomatic or an asymptomatic group, based on their prior history of symptoms that they attributed to VHFS/US. In both groups, overall discomfort ratings were higher in the VHFS/US condition than the reference condition. In the symptomatic group only, difficulty concentrating and annoyance were also rated higher in the VHFS/US than the reference condition. No difference between the two stimulus conditions was seen in performance on the attention task or on average GSRs for either group.

The Effects of Attention Problems on Psychosocial Functioning in Childhood Brain Tumor Survivors: A 2-Year Postcraniospinal Irradiation Follow-up.

OBJECTIVE: To examine the psychosocial outcomes and impact of attention problems in survivors of pediatric brain tumor. STUDY DESIGN: The survivors' cognitive functioning was measured using the Wechsler Intelligence Scale for Children. The Child Behavior Checklist-Attention Problems scale was used to screen for attention problems, and participants were classified as having attention problems (n=15) or normal attention (n=36). Psychosocial functioning was examined with the Korean Personality Rating scale for Children (K-PRC) at precraniospinal radiation and at 2-year follow-up. RESULTS: The attention problem group showed significantly higher depression and externalizing symptoms (delinquency, hyperactivity) and more significant impairment in family relationships than did the normal attention group at baseline. At follow-up, the attention problem group demonstrated significantly more delinquency and impaired family and social relationships. With the K-PRC scores, except for the somatization, social relationship subscale, there were significant differences between groups, but not in terms of treatment by time interaction or within time. At follow-up, multiple linear regressions showed that age at diagnosis significantly predicted K-PRC somatization (B=-1.7, P=0.004) and social relationships (B=-1.7, P=0.004), baseline full-scale intelligence quotient predicted K-PRC depression (B=-0.4, P=0.032) and somatization (B=-0.3, P=0.015), and attention problems at baseline predicted K-PRC depression (B=-15.2, P=0.036) and social relationships (B=-11.6, P=0.016). CONCLUSION: Pediatric brain tumor survivors, in particular, patients with attention problems, had worse psychosocial functioning at baseline and follow-up. Attention problems at baseline need to be carefully evaluated in assessing psychosocial functioning of pediatric brain tumor survivors.

Neurocognitive effects of proton radiation therapy in adults with low-grade glioma.

To understand neurocognitive effects of proton radiation therapy (PRT) in patients with low-grade glioma, we evaluated 20 patients who received this therapy prospectively and over 5 years with a comprehensive neuropsychological battery. 20 patients were evaluated at baseline and at yearly intervals for up to 5 years with a battery of neuropsychological measures that assessed intellectual, attention, executive, visuospatial and memory functions as well as mood and functional status. We evaluated change in cognitive functioning over time. We analyzed the relationship between cognitive performance and tumor location and also examined whether patients' performance differed from that reported in a study of normative practice effects. Overall, patients exhibited stability in cognitive functioning. Tumor location played a role in performance; those with tumors in the left hemisphere versus in the right hemisphere were more impaired at baseline on verbal measures (p < .05). However, we found greater improvement in verbal memory over time in patients with left than with right hemisphere tumors (p < .05). Results of our study, the first to investigate, in depth, neurocognitive effects of PRT in adults with low-grade gliomas, are promising. We hypothesize that the conformal advantage of PRT may contribute to preservation of cognitive functioning, although larger sample sizes and a longer period of study are required. Our study also highlights the need to consider normative practice effects when studying neurocognitive functioning in response to treatment over time, and the need to utilize comprehensive neuropsychological batteries given our findings that differentiate patients with left and right hemisphere tumors.

Long-term decline in intelligence among adult survivors of childhood acute lymphoblastic leukemia treated with cranial radiation.

Survivors of childhood acute lymphoblastic leukemia (ALL) treated with cranial radiation therapy (CRT) are at risk for cognitive impairment, although whether impairment progresses with age into adulthood is unknown. We report change in intelligence for 102 adult survivors of childhood ALL (age range, 26.6-54.7 years) during a median interval of 28.5 years. Survivors demonstrated lower Performance intelligence (mean, 95.3; standard deviation, 16.5; P = .005) but not Verbal IQ (mean, 97.4; standard deviation, 15.44; P = .09) at initial testing. Verbal intelligence declined an average of 10.3 points (P < .0001) during the follow-up interval with no decline in Performance intelligence. Decline was associated with current attention problems (P = .002) but not gender, CRT dose, age at CRT exposure, or years between testing. Results suggest long-term survivors of childhood ALL treated with CRT are at risk for progressive decline in verbal intellect, which may be driven by attention deficits. This trial was registered at clinicaltrials.gov as no. NCT00760656.

Neuropsychological functioning of children treated for acute lymphoblastic leukemia: impact of whole brain radiation therapy.

OBJECTIVES: To provide one of the first prospective reports examining neuropsychological outcomes for children treated with 1800 cGy whole brain radiotherapy (WBRT) and prophylactic chemotherapy versus prophylactic chemotherapy alone for acute lymphoblastic leukemia (ALL). Acute and long-term neuropsychological toxicities associated with WBRT are compared. METHODS: This multisite study included 188 children, ages 4-21 years at enrollment, who were assessed with standardized neuropsychological tests at 9, 21, and 48 months after diagnosis with intermediate risk ALL. All participating children were receiving treatment on a parent study CCG105. RESULTS: Verbal intelligence (VIQ) scores for children receiving WBRT was significantly lower than VIQ for prophylactic chemotherapy at the 48-month time point (p < 0.05). A significant cross-level interaction between time since diagnosis and treatment condition was observed (p < 0.05). WBRT did not result in differences in PIQ; both groups of children demonstrated comparable increases in PIQ. Neuropsychological findings at 48 months after diagnosis indicated diminished performance in neuromotor, visual-motor coordination, and executive functioning for children receiving WBRT. Academic achievement was unaffected by WBRT at 4 years after diagnosis. CONCLUSIONS: The measurement of verbal and performance IQ as a primary endpoint in ALL clinical trials is critical to characterizing neuropsychological late effects. A trajectory of decline in neuropsychological functioning, specifically verbal IQ, was observed. Missing data within the trial occurred at random and did not impact results observed. The impact of WBRT becomes evident at 48 months after diagnosis, suggesting the need for long-term follow-up beyond the time frame typically used in Phase III trials.

Effects of dawn simulation on attentional performance in adolescents.

PURPOSE: This study aimed at examining the effects of 2 weeks of dawn simulation on attentional performance in adolescents. METHODS: On the whole, 56 adolescents (24 females and 32 males) took part to the study, with a mean age of 17.68 ± 0.97 years (age ranging between 15 and 20 years). Each adolescent was requested to participate for 5 consecutive weeks and the research design included the baseline and two counterbalanced conditions, dawn simulator and control (no dawn simulator). Attentional performance of adolescents was measured through the attention network test (ANT) that allowed assessing the efficiency of three separable attentional networks, namely alerting, orienting and executive. Overall, participants performed the ANT three times (i.e., one time for each condition), while sleep quality, sleep duration and sleep timing were concurrently monitored by means of actigraphy and were treated as potential confounders. RESULTS: The only improvement of the attentional performance attributable to the use of dawn simulator was observed for the efficiency of alerting network (45.97 ± 32.76 ms) that significantly increased in comparison to the baseline (31.57 ± 26.97 ms) (p < 0.05). On the contrary, the sleep quality, sleep quantity and sleep timing did not significantly change. CONCLUSION: These results show for the first time that, controlling for sleep quality, sleep duration and sleep timing, the use of dawn simulator across 2 weeks is able to determine an alerting effect in adolescents.

Sleep electroencephalographic characteristics of the Cynomolgus monkey measured by telemetry.

Cynomolgus monkeys are widely used as models of diseases and in pre-clinical studies to assess the impact of new pharmacotherapies on brain function and behaviour. However, the time course of electroencephalographic delta activity during sleep, which represents the main marker of sleep intensity associated with recovery during sleep, has never been described in this non-human primate. In this study, telemetry implants were used to record one spontaneous 24-h sleep-wake cycle in four freely-moving Cynomolgus monkeys, and to quantify the time course of electroencephalographic activity during sleep using spectral analysis. Animals presented a diurnal activity pattern interrupted by short naps. During the dark period, most of the time was spent in sleep with non-rapid eye movement sleep/rapid eye movement sleep alternations and sleep consolidation profiles intermediate between rodents and humans. Deep non-rapid eye movement sleep showed a typical predominance at the beginning of the night with decreased propensity in the course of the night, which was accompanied by a progressive increase in rapid eye movement sleep duration. Spectral profiles showed characteristic changes between vigilance states as reported in other mammalian species. Importantly, delta activity also followed the expected time course of variation, showing a build-up with wakefulness duration and dissipation across the night. Thus, Cynomolgus monkeys present typical characteristics of sleep architecture and spectral structure as those observed in other mammalian species including humans, validating the use of telemetry in this non-human primate model for translational sleep studies.

Please silence your cell phone: Your ringtone captures other people's attention.

Ringtones are designed to draw attention away from on-going activities. In the present study, it was investigated whether the disruptive effects of a ringing cell phone on short-term memory are inevitable or become smaller as a function of exposure and whether (self-) relevance plays a role. Participants performed a serial recall task either in silence or while task-irrelevant ringtones were presented. Performance was worse when a ringing phone had to be ignored, but gradually recovered compared with the quiet control condition with repeated presentation of the distractor sound. Whether the participant's own ringtone was played or that of a yoked-control partner did not affect performance and habituation rate. The results offer insight into auditory distraction by highly attention-demanding distractors and recovery therefrom. Implications for work environments and other applied settings are discussed.

[Prospective longitudinal study on the evolution of autobiographical memory in patients irradiated for benign skull base tumour]. / Étude prospective longitudinale sur l'évolution de la mémoire autobiographique de patients irradiés pour une tumeur bénigne de la base du crâne.

PURPOSE: Cranial irradiation can lead to long-term neurological complications, in particular memory disorders. The aim of this prospective study is to evaluate the impact of irradiation of benign skull base tumours located near the hippocampi on autobiographical memory. PATIENTS AND METHODS: From 2016 to 2019, patients with cavernous sinus meningioma or pituitary adenoma treated with normofractionated irradiation were included. Patients underwent full neuropsychological assessment at baseline, 1year and 2years post-treatment. Neuropsychological tests were converted to Z-Score for comparability. RESULTS: Twelve of the 19 patients included had a complete neuropsychological evaluation at 2years and were analysed. On the "TEMPau" test, no significant difference in autobiographical memory was found at 2years, regardless of the period of autobiographical memory. The mean hippocampal dose had no impact on the variation in autobiographical memory. There was no significant cognitive impairment in the other domains assessed, such as attention, anterograde memory, working memory and executive functions. Autobiographical memory was independent of these other cognitive domains, which justifies its specific study. CONCLUSION: Radiotherapy to the skull base for a benign pathology does not lead to significant cognitive impairment. Longer follow-up would be needed to confirm these results.

Acute exposure to evening blue-enriched light impacts on human sleep.

Light in the short wavelength range (blue light: 446-483 nm) elicits direct effects on human melatonin secretion, alertness and cognitive performance via non-image-forming photoreceptors. However, the impact of blue-enriched polychromatic light on human sleep architecture and sleep electroencephalographic activity remains fairly unknown. In this study we investigated sleep structure and sleep electroencephalographic characteristics of 30 healthy young participants (16 men, 14 women; age range 20-31 years) following 2 h of evening light exposure to polychromatic light at 6500 K, 2500 K and 3000 K. Sleep structure across the first three non-rapid eye movement non-rapid eye movement - rapid eye movement sleep cycles did not differ significantly with respect to the light conditions. All-night non-rapid eye movement sleep electroencephalographic power density indicated that exposure to light at 6500 K resulted in a tendency for less frontal non-rapid eye movement electroencephalographic power density, compared to light at 2500 K and 3000 K. The dynamics of non-rapid eye movement electroencephalographic slow wave activity (2.0-4.0 Hz), a functional index of homeostatic sleep pressure, were such that slow wave activity was reduced significantly during the first sleep cycle after light at 6500 K compared to light at 2500 K and 3000 K, particularly in the frontal derivation. Our data suggest that exposure to blue-enriched polychromatic light at relatively low room light levels impacts upon homeostatic sleep regulation, as indexed by reduction in frontal slow wave activity during the first non-rapid eye movement episode.

No evidence for effects of a high-frequency repetitive transcranial magnetic stimulation series on verbal and figural fluency and TAP task performance in healthy male volunteers.

BACKGROUND: Study results on cognitive effects of repetitive transcranial magnetic stimulation (rTMS) in healthy people are inconsistent. Moreover, former trials performed exclusively single-session stimulations. This sham-controlled study analyzed the influence of 9 serial high-frequency rTMS on cognition. METHODS: 44 young healthy male volunteers received active or sham rTMS. We evaluated verbal fluency tasks, the Ruff Figural Fluency Test and different Test for Attentional Performance tasks (alertness, go/no-go, divided attention, working memory, flexibility) prior to the first stimulation, immediately (within 5-30 min) after stimulation on day 5 and on day 10 (1 day after the last stimulation). RESULTS: Overall, our statistical analyses revealed no significant cognitive effects of serial rTMS. CONCLUSION: In this sham-controlled study design, 9 serial rTMS over the left dorsolateral prefrontal cortex (targeted by the 5-cm rule) did neither enhance nor impair the assessed cognitive functions in healthy male volunteers.

Multiple decrements in switch task performance in female rats exposed to space radiation.

Astronauts on the Artemis missions to the Moon and Mars will be exposed to unavoidable Galactic Cosmic Radiation (GCR). Studies using male rats suggest that GCR exposure impairs several processes required for cognitive flexibility performance, including attention and task switching. Currently no comparable studies have been conducted with female rats. Given that both males and females will travel into deep space, this study determined whether simulated GCR (GCRsim) exposure impairs task switching performance in female rats. Female Wistar rats exposed to 10 cGy GCRsim (n = 12) and shams (n = 14) were trained to perform a touchscreen-based switch task that mimics a switch task used to evaluate pilots' response times. In comparison to sham rats, three-fold more GCRsim-exposed rats failed to complete the stimulus response stage of training, a high cognitive loading task. In the switch task, 50% of the GCRsim-exposed rats failed to consistently transition between the repeated and switch blocks of stimuli, which they completed during lower cognitive loading training stages. The GCRsim-exposed rats that completed the switch task only performed at 65% of the accuracy of shams. Female rats exposed to GCRsim thus exhibit multiple decrements in the switch task under high, but not low, cognitive loading conditions. While the operational significance of this performance decrement is unknown, if GCRSim exposure was to induce similar effects in astronauts, our data suggests there may be a reduced ability to execute task switching under high cognitive loading situations.