Habituation Effects Research Articles

ArTGen: An Arduino-based trigger generator to remotely handle pulse timing in TMS units

Abstract Introduction: Transcranial magnetic stimulation (TMS) protocols are associated with specific combinations of stimulation parameters, including the location of the targeted site, E-field intensity and orientation, pulse shape and duration, variable/fixed inter-pulse interval (IPI), and coil shape and dimension. Among these parameters, IPI may significantly affect the direction of induced neuroplasticity and the possible interference of habituation and expectation effects with TMS-evoked potentials. The TMS units are not always flexible enough to generate customized pulse sequences, thus external devices/software are commonly used. To remotely handle the randomization of IPI, we designed an effective and cheap device (ArTGen – Arduino Uno-based Trigger Generator) for generating arbitrary sequences of square-wave digital pulses. Materials and methods: Using an external foot-switch pedal the TMS experimenter is able to handle the ArTGen’s firmware to remotely drive a customized sequence of pulses in the TMS unit. We designed the firmware to switch among four conditions (single pulse, sequence of jittered pulses, pause and stop) based on a single and double foot-switch taping. We used two BNC sockets to manage respectively the foot-switch signal and the randomized TTLs in output to ArTGen. We tested ArTGen on Magstim Rapid2 with AirFilm® figure-8 coil in tasks with the following characteristics: (i) %Maximal Stimulation Output at 50%; (ii) 100 pulses and (iii) central pulse frequencies set to either 0.1, 5, 10, 15, or 20 Hz. Results: Our results show that all the TTLs released by ArTGen were correctly detected by Magstim Rapid2, and highlight a short delay (computed as the difference between the Arduino trigger and the Magstim Rapid2 output) of about 5μsec across all pulse frequencies. Conclusion: ArTGen is a stand-alone, portable, and not cumbersome opensource device used to randomize TMS pulses or to trigger/synchronize different devices in a closed-loop TMS system with microseconds of accuracy. Keywords: TMS unit, Arduino board, Inter Pulse Interval randomization, Closed Loop TMS System Synchronization

The Onset of Habituation Effects

While extraordinary events like pandemics may prompt an increase in information-seeking behaviour, such trends are unlikely to be sustainable. Over time, issue fatigue/overdose is expected to set in. This study employed generalised additive mixed models (GAMMs) to determine whether attention to TV news corresponded with real-world developments. We sought to predict news use in Germany during the first wave of the COVID-19 pandemic based on disease occurrence next to two well-established predictors of news use (total TV use and day of the week). The association of key events with news use was also assessed. Initially, news use increased with disease occurrence. However, as the pandemic progressed, the linkage between the two variables weakened considerably, suggesting the onset of a habituation effect. Some support emerged for the idea that key events increased news use. Overall, our results are more in line with the explanation provided by agenda-setting theory and various information-seeking models than with the notion of coping through information avoidance. Thus, how the pandemic progresses appears to be a good predictor of news use at the aggregate level, although its predictive power decreases over time.

Stay alert: probability of African Swine Fever introduction from Eastern Asia is almost as high as from Eastern Europe.

African Swine Fever (ASF) is a severe viral disease infecting all suid species. Since the first outbreak in Georgia in 2007, it has slowly spread towards Western Europe and reached the European Union when first cases were detected in Poland and the Baltic States in 2014. ASF was first reported in China in 2018 and since then, it has spread to 14 countries within two years. This study aimed to estimate the introduction probability of ASF from Eastern Asia in a qualitative risk assessment, and to compare it to the probability from Eastern Europe, which was assessed in an earlier risk assessment. A high probability of introduction was estimated for the import of meat and meat products, which was found to be the most likely route of introduction. Less important routes were introduction by human contamination (low probability) or import of feed or blood products (very low probability). Import of domestic pigs or free-ranging wild boar, contaminated means of transport, or infected semen, embryo or ticks were all estimated to be negligible. For Eastern Europe, import of meat and meat products was also estimated to pose a high risk and was therefore the most likely route of introduction. Higher probabilities were estimated for import of live pigs, contaminated feed or means of transport and human contamination. Overall, the probability of introduction from Eastern Asia is only slightly lower than from Eastern Europe. As it is important to detect the first case as quickly as possible, it is important not to fall victim to habituation effects, but to remain vigilant.

Habituation effect in social networks as a potential factor silently crushing influence maximisation efforts

Information spreading processes are a key phenomenon observed within real and digital social networks. Network members are often under pressure from incoming information with different sources, such as informative campaigns for increasing awareness, viral marketing, rumours, fake news, or the results of other activities. Messages are often repeated, and such repetition can improve performance in the form of cumulative influence. Repeated messages may also be ignored due to a limited ability to process information. Learning processes are leading to the repeated messages being ignored, as their content has already been absorbed. In such cases, responsiveness decreases with repetition, and the habituation effect can be observed. Here, we analyse spreading processes while considering the habituation effect and performance drop along with an increased number of contacts. The ability to recover when reducing the number of messages is also considered. The results show that even low habituation and a decrease in propagation probability may substantially impact network coverage. This can lead to a significant reduction in the potential for a seed set selected with an influence maximisation method. Apart from the impact of the habituation effect on spreading processes, we show how it can be reduced with the use of the sequential seeding approach. This shows that sequential seeding is less sensitive to the habituation effect than single-stage seeding, and that it can be used to limit the negative impact on users overloaded with incoming messages.

Functional Activities Detected in the Olfactory Bulb and Associated Olfactory Regions in the Human Brain Using T2-Prepared BOLD Functional MRI at 7T.

Olfaction is a fundamental sense that plays a vital role in daily life in humans, and can be altered in neuropsychiatric and neurodegenerative diseases. Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) using conventional echo-planar-imaging (EPI) based sequences can be challenging in brain regions important for olfactory processing, such as the olfactory bulb (OB) and orbitofrontal cortex, mainly due to the signal dropout and distortion artifacts caused by large susceptibility effects from the sinonasal cavity and temporal bone. To date, few studies have demonstrated successful fMRI in the OB in humans. T2-prepared (T2prep) BOLD fMRI is an alternative approach developed especially for performing fMRI in regions affected by large susceptibility artifacts. The purpose of this technical study is to evaluate T2prep BOLD fMRI for olfactory functional experiments in humans. Olfactory fMRI scans were performed on 7T in 14 healthy participants. T2prep BOLD showed greater sensitivity than GRE EPI BOLD in the OB, orbitofrontal cortex and the temporal pole. Functional activation was detected using T2prep BOLD in the OB and associated olfactory regions. Habituation effects and a bi-phasic pattern of fMRI signal changes during olfactory stimulation were observed in all regions. Both positively and negatively activated regions were observed during olfactory stimulation. These signal characteristics are generally consistent with literature and showed a good intra-subject reproducibility comparable to previous human BOLD fMRI studies. In conclusion, the methodology demonstrated in this study holds promise for future olfactory fMRI studies in the OB and other brain regions that suffer from large susceptibility artifacts.

Zebrafish larva’s response and habituation to electric signal: Effects of voltage, current and pulsation studied in a microfluidic device

We previously showed that electric current induces zebrafish larvae to move towards the anode pole along a microchannel. For a larva with a fixed head and a moving tail, we observed that the response to electricity depended on the current magnitude. The effects of electric signal direction, voltage magnitude and habituation to repeated exposures to electric pulses were not characterized. Here, this knowledge gap was addressed by exploiting them in a microfluidic device with a head-trap to immobilize a zebrafish larva and a downstream chamber for tail movement phenotypic characterization based on response duration (RD) and tail beat frequency (TBF). We first assessed larvae’s response to electric current direction (at 3 µA) and voltage magnitude. Changing the current direction significantly altered the RD and TBF with long and low-frequency responses seen when the anode was positioned at the larvae’s tail. The electric voltage had a significant effect on larvae’s locomotion with long RD and low TBF observed at 5.6 V in the range of 1.3–9 V. We also demonstrated that the zebrafish locomotor response to repeated 3 µA current pulses diminished with dependency on the interstimulus interval. However, the diminished response was fully recovered after a 5-min resting period or introduction of a novel light stimulus (i.e., habituation-dishabituation strategy). Therefore, electric response suppression in zebrafish was attributed to the habituation as a form of non-associative learning. Our microfluidic platform has a broad application potential in behavioral neuroscience to study cognitive phenotypes, fundamental studies on the biological roots of electric response, and in pharmacological screening.

The effects of habituation on boldness of urban and rural song sparrows (Melospiza melodia)

Abstract As urbanization increases globally, wildlife species are changing their behaviour in many ways. Urban animals are often bolder, or less fearful of new stimuli, than rural animals. While adaptation can drive behavioural changes in urban animals, other factors, such as learning or habituation, can also lead to behavioural modifications. To determine how repeated exposure to a non-threatening human affects song sparrow (Melospiza melodia) behaviour in urban and rural habitat, we measured boldness as flight initiation distance (FID), for 5 consecutive days. We found that urban birds had consistently lower FID’s than their rural counterparts from days 1–4, yet there was no difference in rural and urban FID by trial 5. FID decreased over 5 days of repeated trials in the rural populations, but not the urban. These results suggest that habituation can occur quickly in rural birds and may account for the greater boldness we typically see in urban populations.

Neurophysiological and clinical effects of the NMDA receptor antagonist lanicemine (BHV-5500) in PTSD: A randomized, double-blind, placebo-controlled trial.

Posttraumatic stress disorder (PTSD) is associated with hyperarousal and stress reactivity, features consistent with behavioral sensitization. In this Phase 1b, parallel-arm, randomized, double-blind, placebo-controlled trial, we tested whether the selective low-trapping N-methyl-D-aspartate receptor (NMDAR) antagonist [Lanicemine (BHV-5500)] blocks expression of behavioral sensitization. Twenty-four participants with elevated anxiety potentiated startle (APS) and moderate-to-severe PTSD symptoms received three infusions of lanicemine 1.0 mg/ml (100 mg) or matching placebo (0.9% saline) (1:1 ratio), over a 5-day period. The primary outcome was change in APS from baseline to end of third infusion. We also examined changes in EEG gamma-band oscillatory activity as measures of NMDAR target engagement and explored Clinician-Administered PTSD Scale (CAPS-5) hyperarousal scores. Lanicemine was safe and well-tolerated with no serious adverse events. Using Bayesian statistical inference, the posterior probability that lanicemine outperformed placebo on APS T-score after three infusions was 38%. However, after the first infusion, there was a 90% chance that lanicemine outperformed placebo in attenuating APS T-score by a standardized effect size more than 0.4. We demonstrated successful occupancy of lanicemine on NMDAR using gamma-band EEG and effects on hyperarousal symptoms (Cohen's d = 0.75). While lanicemine strongly attenuated APS following a single infusion, differential changes from placebo after three infusions was likely obscured by habituation effects. To our knowledge, this is the first use of APS in the context of an experimental medicine trial of a NMDAR antagonist in PTSD. These findings support selective NMDAR antagonism as a viable pharmacological strategy for salient aspects of PTSD.

Revealing the time course of laser-evoked potential habituation by high temporal resolution analysis.

Reduced laser-evoked potential (LEP) habituation indicates abnormal central pain processing. But the paradigm (four stimulation blocks a 25 stimuli) is time consuming and potentially omits important information on the exact habituation time course. This study examined whether a high temporal resolution (HTR) analysis (dividing the four stimulation blocks into 12 analysis blocks) can answer the following questions: (a) After how many stimuli does LEP habituation occur? (b) Is there a difference in LEP habituation in younger versus older subjects? (c) Is HTR applicable on radiculopathy patients? EEG data of 129 subjects were included. Thirty-four young healthy and 28 advanced-aged healthy subjects were tested with LEPs on the hand dorsum. Thirty-seven radiculopathy patients and 30 controls were tested with LEPs on the L3 dermatome. The EEG data of the hand dorsa have been analysed conventionally and with HTR analysis. The applicability of HTR has been tested on radiculopathy patients and respective controls. HTR was well feasible in young healthy subjects and revealed a strong habituation effect during the first 25 stimuli (i.e. within the first 5min). After approximately 48 stimuli, no further significant habituation was detectable. LEP amplitudes were higher in young subjects. HTR was unsuitable for elderly subjects and middle-aged radiculopathy patients. In young healthy subjects, HTR allows a shortening of the test protocol while providing a detailed information on the time course of LEP habituation. A shorter protocol might be useful for the applicability of the LEP paradigm for clinical and experimental settings as well as pharmacological studies. The usage of high temporal resolution (HTR) analysis in young healthy subjects enables a short test protocol and provides the exact time course of laser-evoked potential habituation. This can be useful for the examination of neurological conditions affecting younger patients and for pharmacological studies. HTR was inapplicable in advanced-aged subjects and patients with radiculopathy.

Psychological and Physiological Effects of Imagery Rescripting for Aversive Autobiographical Memories

BackgroundImagery Rescripting (ImRs) is a promising intervention to reduce symptoms associated with aversive memories, but little is known about its working mechanisms. The present study investigates whether ImRs increases perceived mastery and attenuates emotional reactivity to memory retrieval on a subjective and physiological level.MethodsSeventy-nine individuals reporting memories of distressing real-life events were randomly allocated to ImRs, positive imagery (PI), or no-intervention control (NIC). The memory was reactivated before the intervention and at 1-week follow-up to assess subjective measures and physiological reactivity (heart rate [HR], skin conductance level [SCL], and facial electromyography activity [EMG]) during memory retrieval.ResultsImRs was superior to PI and NIC on subjective memory distress and helplessness, but not on other emotions. ImRs did not exceed PI and NIC in reducing state stress symptoms or increasing perceived mastery. Physiological reactivity (HR, EMG) decreased from pre-intervention to follow-up with no differences between groups.ConclusionsPositive effects of ImRs on helplessness and distress were found. Null findings regarding mastery might result from timing of its assessment or the fact that rather high-functioning participants were included. The lack of between group differences on physiological responses indicates that ImRs did not exceed habituation effects in the present sample.

The repeated Montreal Imaging Stress Test (rMIST): Testing habituation, sensitization, and anticipation effects to repeated stress induction

BackgroundA psychosocial task that can induce comparable levels of stress repeatedly is fundamental to effectively study changes in stress reactivity over time or as a result of an intervention. However, existing tasks have struggled to provide consistent stress responses across repeated trials. AimThe goal was to assess the efficacy of two different designs of the repeated Montreal Imaging Stress Test (rMIST) in reproducing the same pattern of reactivity over two separate sessions. MethodsIn two different studies, stress was induced using the rMIST on two separate sessions, one week apart. Each study used a different task design. In the first study (53 participants [45 women]; mean age=24.16 [SD=3.29]), the rMIST consisted of a single-longer stress exposure, while the second study (30 participants [27 women]; mean age=21.81 [SD=2.09]) consisted of several shorter stress exposures per session. Self-reported (i.e perceived stress [PS] and negative affect [NA]), physiological (i.e heart rate [HR], root mean square of successive differences [RMSSD]) and hormonal (i.e. salivary cortisol) measures of stress were used. ResultsStress reactivity was comparable across the two repeated stress sessions in both studies. However, baseline HR in the second session increased relative to the first session in the first study, and there was no cortisol response. Additionally, there was a decrease in HR and HRV reactivity within the session on the second study, suggesting a habituation effect not between but within the session itself. ConclusionThe rMIST overcomes some of the challenges associated with repeated stress induction. However, an anticipation effect and a lack of cortisol response indicate that further adjustments to the task are necessary. Finally, task design is important for repeated stress reactivity.

First encounter effects in testing of highly automated vehicles during two experimental occasions – The need for recurrent testing

Abstract To explore driver behavior in highly automated vehicles (HAVs), independent researchers are mainly conducting short experiments. This limits the ability to explore drivers’ behavioral changes over time, which is crucial when research has the intention to reveal human behavior beyond the first-time use. The current paper shows the methodological importance of repeated testing in experience and behavior related studies of HAVs. The study combined quantitative and qualitative data to capture effects of repeated interaction between drivers and HAVs. Each driver ( n = 8 n=8 ) participated in the experiment on two different occasions (∼90 minutes) with one-week interval. On both occasions, the drivers traveled approximately 40 km on a rural road at AstaZero proving grounds in Sweden and encountered various traffic situations. The participants could use automated driving (SAE level 4) or choose to drive manually. Examples of data collected include gaze behavior, perceived safety, as well as interviews and questionnaires capturing general impressions, trust and acceptance. The analysis shows that habituation effects were attenuated over time. The drivers went from being exhilarated on the first occasion, to a more neutral behavior on the second occasion. Furthermore, there were smaller variations in drivers’ self-assessed perceived safety on the second occasion, and drivers were faster to engage in non-driving related activities and become relaxed (e. g., they spent more time glancing off road and could focus more on non-driving related activities such as reading). These findings suggest that exposing drivers to HAVs on two (or more) successive occasions may provide more informative and realistic insights into driver behavior and experience as compared to only one occasion. Repeating an experiment on several occasions is of course a balance between the cost and added value, and future research should investigate in more detail which studies need to be repeated on several occasions and to what extent.

Naphthalene: irritative and inflammatory effects on the airways

ObjectiveThis cross-sectional study determined whether acute sensory irritative or (sub)chronic inflammatory effects of the eyes, nose or respiratory tract are observed in employees who are exposed to naphthalene at the workplace.MethodsThirtynine healthy and non-smoking male employees with either moderate (n = 22) or high (n = 17) exposure to naphthalene were compared to 22 male employees from the same plants with no or only rare exposure to naphthalene. (Sub)clinical endpoint measures included nasal endoscopy, smell sensitivity, self-reported work-related complaints and the intensity of naphthalene odor and irritation. In addition, cellular and soluble mediators in blood, nasal lavage fluid (NALF) and induced sputum (IS) were analysed. All measurements were carried out pre-shift on Monday and post-shift on Thursday. Personal air monitoring revealed naphthalene shift concentrations up to 11.6 mg/m3 with short-term peak concentrations up to 145.8 mg/m3 and 1- and 2-naphthol levels (sum) in post-shift urine up to 10.1 mg/L.ResultsAcute sensory irritating effects at the eyes and upper airways were reported to occur when directly handling naphthalene (e.g., sieving pure naphthalene). Generally, naphthalene odor was described as intense and unpleasant. Habituation effects or olfactory fatigue were not observed. Endoscopic examination revealed mild inflammatory effects at the nasal mucosa of exposed employees in terms of reddening and swelling and abnormal mucus production. No consistent pattern of cellular and soluble mediators in blood, NALF or IS was observed which would indicate a chronic or acute inflammatory effect of naphthalene in exposed workers.ConclusionsThe results suggest that exposure to naphthalene induces acute sensory irritative effects in exposed workers. No (sub)chronic inflammatory effects on the nasal epithelium or the respiratory tract could be observed under the study conditions described here.

Functional Decoupling of Emotion Coping Network Subsides Automatic Emotion Regulation by Implementation Intention.

Automatic emotion regulation (AER) plays a vital role in the neuropathology underlying both suicide and self-harm via modifying emotional impact effortlessly. However, both the effortless account and the neural mechanisms of AER are undetermined. To investigate the neural changes at AER, we collected functional MRI (fMRI) in 31 participants who attended to neutral and disgust pictures in three conditions: watching, goal intention (GI), and reappraisal by implementation intention (RII). Results showed that RII (but not GI) decreased negative feelings and bilateral amygdala activity without increasing cognitive efforts, evidenced by the reduced effort rating and less prefrontal engagement during RII compared with during watching and GI. These emotion-regulatory effects of RII cannot be explained by emotional habituation, as the supplementary experiment (N = 31) showed no emotional habituation effects when the same disgust pictures were presented repeatedly three times for each watching and GI condition. Task-based network analysis showed both RII and GI relative to watching increased functional connectivities (FCs) of the ventral anterior cingulate cortex to the left insula and right precuneus during conditions, two FCs subserving goal setup. However, RII relative to GI exhibited weaker FCs in brain networks subserving effortful control, memory retrieval, aversive anticipation, and motor planning. In these FCs, the FC intensity of putamen-operculum/lingual and paracentral-superior temporal gyri positively predicted regulatory difficulty ratings. These findings suggest that the setup of implementation intention automatizes emotion regulation by reducing the online mobilization of emotion-coping neural systems.

Horizontal vs. Vertical Recommendation Zones Evaluation Using Behavior Tracking

Recommender systems play a vital role in e-commerce by increasing the likelihood of transactions and improving sales thanks to presenting personal recommendations. Due to the marketing habituation effect, users are less and less responsive to this type of content. Visual recommendation presentation, in particular the recommendation zone layout can influence the effectiveness of a recommendation. This study examines human–computer interactions for vertical, horizonal, and mixed layouts of recommending interfaces of four major e-commerce stores, and is based on our document object model events-based behavior analysis tool. Results from this implicit feedback study are presented and analyzed, showing that vertical recommendation zones attracted more attention than horizontal ones.

Increasing the reliability of stress tolerance prediction as part of aptitude screening of flight specialists

Aim . The paper describes a research aimed at improving the reliability of stress tolerance prediction as part of aptitude screening (AS) of flight school applicants using a proprietary objectifying method of Stress Tolerance Assessment. Stress tolerance (ST) is an important psychophysiological professional quality and serves as one of the factors ensuring both successful flight training, and further professional flight work. However, the methods recommended in regulatory documents for the purpose of ST identification as part of AS are not efficient enough and are affected by subjective factors. Therefore, an objective and thus more efficient method is still required. Methods . The method was developed based on the analysis of subject-matter literature and own experience. Stress stimuli and methods of indicator recording were selected based on their empirical verification. The stress-inducing property of the stimuli was confirmed by the pulse rate increase by 40 – 100% and higher, associated behavioural manifestations and significant dynamics of mental productivity in the course of tests. Out of the methods of mathematical statistics, the authors used correlation analysis. Results . The method of ST assessment is based on the Reakor multifunctional psychophysiological system by the Medicom MTD research and development company from Taganrog, Russia, with a proprietary procedure built in the system’s software. As stress stimulus material and for performance assessment, arithmetically complicated problems were selected, whose solutions involve a larger portion (areas) of the brain than verbal tests. In order to eliminate the effect of habituation and learning, the arithmetic tests were displayed one by one on a computer screen in a random order. The 3-4-second time interval between individual problems was selected based on premises of aviation psychology and tests conducted on a group of students. The sample consisted of 1135 male applicants to the higher flight school in 2016. Correlation analysis shows that the correlations between the external criterion indicators (successful simulator training and flying practice) and the integrated ST indicator are statistically significant: the higher is the ST indicator measured in the course of AS using the respective method, the higher are the expert estimates of the simulator training and flying practice. Conclusion . Thus, the conducted research showed that the application of the developed method of ST assessment in the course of higher flight school AS ensures higher predicted stress tolerance in the selected candidates as the psychophysiological factor of professional efficiency and reliability of flight personnel.

Habituation to Transport Helps Reducing Stress-Related Behavior in Donkeys During Loading

Adopting proper animal management strategies, including training, might reduce to a substantial extent the adverse effects of transport-related stress in animals. The aim of this study was to evaluate the effect of habituation to transport on stress-related behaviors and physiological indicators during loading and unloading in donkeys. Fourteen donkeys were recruited and divided in two treatment groups: Habituation (H; M = 5, F = 2) and Control (C; M = 5, F = 2). H donkeys were gradually habituated to be transported, traveling together with their mothers and other adult donkeys well-accustomed to transport, while C donkeys had never been transported before. Loading and unloading phases were video recorded and behavior was analyzed. Saliva samples for cortisol concentration determination were collected at rest and after unloading. Latency time to load was significantly shorter for H donkeys than C donkeys (Mann-Whitney; p = 0.004). C donkeys also showed significantly more stress-related behaviors (Mann-Whitney; p = 0.026) and required a higher but not statistically significant number of human interventions to load. Cortisol concentration increased in both groups, but no differences were found between them (Mann-Whitney; p > 0.05). These results suggest that habituation to transport could mitigate stress during loading procedures in donkeys reducing loading time, frequency of stress-related behaviors and diminishing the need of human intervention.

Come Closer: Experimental Investigation of Robots’ Appearance on Proximity, Affect and Trust in a Domestic Environment

From once being utopian, robots become more and more common in public and private social life. One area of application are robots, which are able to perform chores in domestic environments. To support users accustoming to the new robot companion, psychological mechanisms that enhance the interaction with robots need to be understood. In this research, the effects of robot’s height and manipulator position on proximity, affect and trust with regards to a humanoid robot were investigated in a laboratory experiment. Results indicated an effect of robot’s height on the comfort distance. On the other hand, a habituation effect after a second robot-human approach was found, in which the influence of the robot’s height on proximity diminished. Similar effects with an anxiety decrease and trending trust increase in the tall robot over time emphasize the importance of first encounters, which should be paid special attention to by designers of robotic systems.

A time and a place: A framework for caffeine periodization throughout the sporting year.

Caffeine is a well-established ergogenic aid, with its performance-enhancing effects demonstrated across a variety of sports and exercise types. As a result of these ergogenic properties, caffeine is widely used by athletes at all levels around both competition and training. Caffeine exerts its performance benefits through a variety of mechanisms, each of which may be of increased importance at a given stage of training or competition. Additionally, regular caffeine use may diminish the performance-enhancing effects of a subsequent dose of caffeine. Recently, interest in the concept of nutritional periodization has grown. Here we propose a framework for the periodization of caffeine through the sporting year, balancing its training and competition performance-enhancing effects, along with the need to mitigate any negative effects of habituation. Furthermore, the regular use of caffeine within training may support the development of positive beliefs toward caffeine by athletes-potentially serving to enhance future performance through placebo and expectancy mechanisms-as well as allowing for the optimization of individual athlete caffeine strategies. Although future work is required to validate some of the suggestions made, the framework proposed here represents a starting point for athletes to maximize caffeine's performance benefits across the sporting year.

Development of Neural Response to Novel Sounds in Fragile X Syndrome: Potential Biomarkers.

Auditory processing abnormalities in fragile X syndrome (FXS) may contribute to difficulties with language development, pattern identification, and contextual updating. Participants with FXS (N = 41) and controls (N = 27) underwent auditory event-related potentials during presentation of an oddball paradigm. Data was adequate for analysis for 33 participants with FXS and 27 controls (age 4-51 y, 13 females [FXS]; 4-54 y, 11 females [control]). Participants with FXS showed larger N1 and P2 amplitudes, abnormal lack of modulation of P1 and P2 amplitudes and P2 latency in response to oddball stimuli ) relative to controls: Females with FXS were more similar to controls. Participants with FXS showed a marginal speeding of the P2 latency, suggesting potentiation to oddball stimuli rather than habituation. Participants with FXS showed a heightened N1 habituation effect compared to controls. Gamma power was significantly higher for participants with FXS. Groups did not differ on mismatch negativity. Both controls and participants with FXS showed similar developmental trajectories in P1 and N1 amplitude, P2 latency, and gamma power, but not for P2 amplitude. One month retest analyses performed in 14 participants suggest strong test-retest reliability for most measures. Individuals with FXS show previously demonstrated increased response amplitude and high frequency neural activity. Despite an overall normal developmental trajectory for most measures, individuals with FXS show age-independent but gender-dependent decreases in complex processing of novel stimuli. Many markers show strong retest reliability even in children and thus are potential biomarkers for clinical trials in FXS.