Variation In Activity Patterns Research Articles

Distributed representation of social odors indicates parallel processing in the antennal lobe of ants

In colonies of eusocial Hymenoptera cooperation is organized through social odors, and particularly ants rely on a sophisticated odor communication system. Neuronal information about odors is represented in spatial activity patterns in the primary olfactory neuropile of the insect brain, the antennal lobe (AL), which is analog to the vertebrate olfactory bulb. The olfactory system is characterized by neuroanatomical compartmentalization, yet the functional significance of this organization is unclear. Using two-photon calcium imaging, we investigated the neuronal representation of multicomponent colony odors, which the ants assess to discriminate friends (nestmates) from foes (nonnestmates). In the carpenter ant Camponotus floridanus, colony odors elicited spatial activity patterns distributed across different AL compartments. Activity patterns in response to nestmate and nonnestmate colony odors were overlapping. This was expected since both consist of the same components at differing ratios. Colony odors change over time and the nervous system has to constantly adjust for this (template reformation). Measured activity patterns were variable, and variability was higher in response to repeated nestmate than to repeated nonnestmate colony odor stimulation. Variable activity patterns may indicate neuronal plasticity within the olfactory system, which is necessary for template reformation. Our results indicate that information about colony odors is processed in parallel in different neuroanatomical compartments, using the computational power of the whole AL network. Parallel processing might be advantageous, allowing reliable discrimination of highly complex social odors.

Crepuscular Flight Activity of Culex erraticus (Diptera: Culicidae)

Circadian patterns of flight activity in mosquitoes can influence pathogen transmission by regulating dispersal potential of vectors and contact rates between vectors and reservoir and/or dead-end hosts. We investigated circadian activity patterns of Culex erraticus (Dyar and Knab) at a wetland field site in central Alabama, by aspirating resting adults and questing females in the morning and evening hours, respectively. Mosquitoes were aspirated at regular time intervals to determine the time of day during which peak resting site-seeking and host-seeking activities occurred. Day-to-day variation in activity patterns due to wind, humidity, and temperature was examined using stepwise linear regression. We found a distinct peak in flight activity during the morning hours (2 h before and 2 h after sunrise) for females and males of Culex erraticus, the most commonly encountered species at the site. The exact time of the peak varied from day to day, and was largely a function of temperature. A less distinct peak in activity was observed for questing females in the evening, although flights generally commenced just after sunset and peaked 30-60 min after sunset. A significant amount of day-to-day variation in the number of questing females was attributable to relative humidity. Our study demonstrates predictable patterns of circadian activity for Cx. erraticus, a suspected bridge vector of eastern equine encephalitis virus. Moreover, these patterns are modulated by environmental conditions. This information may be used to develop vector control strategies and make predictions about factors that affect the spread of mosquito-vectored pathogens.

How Children Move: Activity Pattern Characteristics in Lean and Obese Chinese Children

Physical activity and sedentary behavior are central components of lifetime weight control; however, our understanding of dimensions of these behaviors in childhood is limited. This study investigated free-living activity pattern characteristics and the individual variability of these characteristics in 84 lean and obese Chinese children (7–9 y) during the school day and over the weekend. Activity pattern characteristics were established from triaxial accelerometry (StayHealthy RT3). Results indicated that children's free-living activity is characterized by many short-duration, low-intensity bouts of movement. Obese children take longer rest intervals between bouts and engage in fewer activity bouts both at school and at home. Intraindividual variability in activity patterns was low during school days but high for the rest intervals between bouts and number of activity bouts per day at the weekend. Finding ways to reduce the rest time between bouts of movement and increase the number of movement bouts a child experiences each day is an important next step.

Nest-Activity Patterns and Food-Provisioning Rates by Great Egrets (Ardea alba)

Abstract. Information on nest-activity patterns and energetic costs during the breeding season may shed light on current population trends of Great Egrets (Ardea alba). To address the issue, Great Egrets nesting in a mixed species colony in Wichita, Kansas, were studied from May–July in 2008 and 2009. A total of 35 h of scan samples at 28 random nests resulted in 5,062 instantaneous records; a separate 62 h of observations recorded 75 food-provisioning intervals. Adults at the nest engaged mainly in low-cost activities such as sitting, standing and preening, but activity patterns differed significantly by nest content. Adults with eggs spent significantly more time sitting but less time standing, preening or away from the nest. Overall variation in activity patterns among the 28 study nests was not significant. Food-provisioning intervals ranged from 6-480 min, with a median duration of 180 min. Intervals declined significantly with chick stage, were longer during periods of high wind velocity, and varied...

The geography of recreational physical activity in England

Levels of physical activity have declined considerably over recent decades in England, and there is evidence that activity patterns vary across areas. Previous studies of the geography of physical activity have frequently relied on model based synthetic estimates. Using data from a large population survey this study develops a direct measure of recreational physical activity and investigates variations in activity patterns across English Local Authorities. For both sexes the results show a distinct geography of recreational physical activity associated with north/south variations and urban/rural status. The environmental and behavioural factors driving those patterns are still poorly understood. We conclude that the variations observed might reflect recreational opportunities and the socio-cultural context of areas.

I07 Image-HD: a functional magnetic resonance imaging study of spatial working memory in Huntington's disease

BackgroundWhile involuntary motor dysfunction is most commonly used as the hallmark of manifest Huntington's disease (HD), cognitive functions are known to decline decades before the presence of motor symptoms.AimsWe used...

Simpler Is Better

“It has long been an axiom of mine that the little things are infinitely the most important” — —Sherlock Holmes in “A Case of Identity” by Arthur Conan Doyle Cardiac resynchronization therapy (CRT) can have a profound therapeutic impact on appropriately selected patients. However, even when the current clinical guidelines for CRT1 are rigorously applied, the response rate is ≈70%. Nearly a third of patients who undergo implantation of a CRT device are clinical nonresponders and more may be “remodeling nonresponders.” An extensive body of literature reports on a wide variety of methods that can be better used to identify potential responders by measurement of mechanical dyssynchrony. Factors responsible for nonresponse include comorbid conditions, cardiac substrate, left ventricular (LV) lead location, and device programming. Comorbid conditions such as obstructive sleep apnea, right-sided heart failure, and type of intraventricular conduction delay should be considered at the preprocedural stage. Device programming may help minimize the number of nonresponders. Prediction of responders by invasive hemodynamic assessment is impractical for daily clinical practice. Cardiac magnetic resonance imaging is too expensive for routine use and is not an option for many patients who already have devices and need upgrades. The appeal of echocardiography for predicting responders by identifying mechanical dyssynchrony has been dampened by its limited reproducibility and poor predictive value.2 It is also impractical to perform echocardiography during implantations. The prolonged QRS duration (QRSd; electric dyssynchrony), as measured on a standard 12-lead ECG, remains the best method for identifying candidates for CRT. In an elegant and important study reported in this issue of Circulation , Sweeney and colleagues3 use the 12-lead ECG and show that, despite its apparent simplicity, analysis of the standard 12-lead ECG can yield both pitfalls and impressive rewards. Article see p 626 Current clinical guidelines specify a …

Activity Patterns and Sharing of Time and Space of Platypuses, Ornithorhynchus anatinus, in a Subalpine Tasmanian Lake

We investigated the activity patterns of platypuses, Ornithorhynchus anatinus, at Lake Lea, a subalpine lake in Tasmania. Platypuses were equipped with activity loggers or time–depth recorders, which allowed constant recordings for up to 48 days. The recordings revealed an unexpectedly high variety of foraging behaviors. Although nocturnal activity, as reported from other habitats, was still predominant, diurnal activity as well as highly fragmented activity patterns were common. Mean foraging duration was 12.4 h/day, with some animals foraging continuously for up to 29.8 h. Daily emergence and return times as well as durations of daily foraging trips varied considerably. At least 2 animals showed a distinct shift in activity pattern related to the lunar cycle. Season and water temperature affected platypus behavior. Foraging durations were longer and activity levels were higher in winter. In contrast to observations in river systems, temporal separation likely served as a mechanism to avoid intraspecific competition, and was particularly important for adult males during the breeding season. Dominant males were preferentially nocturnal, whereas lower-ranked males adopted more variable or fragmented activity patterns.

Ventricular reentrant arrhythmia due to regional differences - A computational Study

For many years the most accepted hypothesis is the mechanism of fibrillation in turn leads to arrhythmia was that the anatomical and electrophysiological heterogeneity in cardiac tissue. Regional differences in action potential duration (APD) and changes in depolarization in the heart favor re-entrant arrhythmia. With the help of mathematical model of ventricle cell, the role of sodium on 2D grid of cells in establishing arrhythmia is studied. First a homogeneous tissue of 60×60 was considered with all the parameters are identical. Next the heterogeneity in the tissue has been formed with the help of small squares by varying sodium conductance (gNa) values from its nominal. Also spatial heterogeneity in the tissue has been formed by setting gNa values of some of the squares at deviated values from its nominal. Due to heterogeneity among the cells in the tissue, the action potential (AP) propagation in the tissue is totally arrhythmic. The regional variation in gNa at the center square showed that cells in that region where gNa is varied gets disturbed (i.e. not able to depolarize). Next study, the regional differences in gNa[[Unsupported Character - Codename ­]] is increased to three squares in diagonal wise. It is observed that the activity pattern of AP propagation in the tissue almost gets disturbed and spiral waves start originating from the center of the squares. Next analysis the number of squares increased to five. Compared to all previous cases, the variation in activity pattern of AP is totally gets collapsed in this case. Further, it is observed that multiple spirals are formed in the tissue around the region where regional differences are made. This multiple spirals further propagated to the entire tissue and causes re-entrant arrhythmia.

Movement patterns of feral predators in an arid environment – implications for control through poison baiting

Control of introduced predators is critical to both protection and successful reintroduction of threatened prey species. Efficiency of control is improved if it takes into account habitat use, home range and the activity patterns of the predator. These characteristics were studied in feral cats (Felis catus) and red foxes (Vulpes vulpes) in arid South Australia, and results are used to suggest improvements in control methods. In addition, mortality and movement patterns of cats before and after a poison-baiting event were compared. Thirteen cats and four foxes were successfully fitted with GPS data-logger radio-collars and tracked 4-hourly for several months. High intra-specific variation in cat home-range size was recorded, with 95% minimum convex polygon (MCP) home ranges varying from 0.5 km2 to 132 km2. Cat home-range size was not significantly different from that of foxes, nor was there a significant difference related to sex or age. Cats preferred habitat types that support thicker vegetation cover, including creeklines and sand dunes, whereas foxes preferred sand dunes. Cats used temporary focal points (areas used intensively over short time periods and then vacated) for periods of up to 2 weeks and continually moved throughout their home range. Aerial baiting at a density of 10 baits per km2 was ineffective for cats because similar high mortality rates were recorded for cats in both baited and unbaited areas. Mortality was highest in young male cats. Long-range movements of up to 45 km in 2 days were recorded in male feral cats and movement into the baited zone occurred within 2 days of baiting. Movement patterns of radio-collared animals and inferred bait detection distances were used to suggest optimum baiting densities of ~30 baits per km2 for feral cats and 5 per km2 for foxes. Feral cats exhibited much higher intra-specific variation in activity patterns and home-range size than did foxes, rendering them a potentially difficult species to control by a single method. Control of cats and foxes in arid Australia should target habitats with thick vegetation cover and aerial baiting should ideally occur over areas of several thousand square kilometres because of large home ranges and long-range movements increasing the chance of fast reinvasion. The use of temporary focal points suggested that it may take several days or even weeks for a cat to encounter a fixed trap site within their home range, whereas foxes should encounter them more quickly as they move further each day although they have a similar home-range size. Because of high intra-specific variability in activity patterns and home-range size, control of feral cats in inland Australia may be best achieved through a combination of control techniques.

Echocardiographic estimation of acute haemodynamic response during optimization of multisite pace-maker using different pacing modalities and atrioventricular delays

Cardiac resynchronization therapy (CRT) improves ventricular dyssynchrony and is associated with an improvement in symptoms, quality of life and prognosis in patients with severe heart failure and intraventricular conduction delay. Different pacing modalities produce variable activation patterns and may be a cause of different haemodynamic changes. The aim of our study was to investigate acute haemodynamic changes with different CRT configurations during optimization procedure. This study included 30 patients with severe left ventricular systolic dysfunction and left bundle branch block with wide QRS (EF 24.33 +/- 3.7%, QRS 159 +/- 17.3 ms, New York Heart Association III/IV 25/5) with implanted CRT device. The whole group of patients had severe mitral regurgitation in order to measure dP/dt. After implantation and before discharge all the patients underwent optimization procedure guided by Doppler echocardiography. Left and right ventricular pre-ejection intervals (LVPEI and RVPEI), interventricular mechanical delay (IVD) and the maximal rate of ventricular pressure rise during early systole (max dP/dt) were measured during left and biventricular pacing with three different atrioventricular (AV) delays. After CRT device optimization, optimal AV delay and CRT mode were defined. Left ventricular pre-ejection intervals changed from 170.5 +/- 24.6 to 145.9 +/- 9.5 (p < 0.001), RVPEI from 102.4 +/- 15.9 to 119.8 +/- 10.9 (p < 0.001), IVD from 68.1 +/- 18.3 to 26.5 +/- 8.2 (p < 0.001) and dP/dt from 524.2 +/- 67 to 678.2 +/- 88.5 (p < 0.01). In patients receiving CRT echocardiographic assessment of the acute haemodynamic response to CRT is a useful tool in optimization procedure. The variability of Doppler parameters with different CRT modalities emphasizes the necessity of individualized approach in optimization procedure.

Determinants of seasonal variation in activity patterns of mouflon

Balancing energetic requirements is a complex process governed by the current condition of the animal, its physiological state, and by the local environment. In response to these factors, animals are expected to adapt their activity patterns. Based on continuous monitoring of 14 GPS-collared animals in southern France, we studied how environmental conditions and reproductive life-cycle periods shape the monthly activity patterns of free-ranging female mouflon ( Ovis gmelini musimon × Ovis sp. (Blyth, 1841)). More specifically, we analyzed total daily activity, diurnal activity, length of activity bouts, and number of activity bouts. We performed multivariate analyses to account for the relationship between several intercorrelated explanatory variables and monthly activity variables. Mouflon decreased their daily activity, diurnal activity, and length of activity bouts during the hot summer months. Such changes might allow animals to reduce thermoregulation costs. The resulting higher activity in winter compared with summer indicates that summer is the most limiting period for large herbivores in Mediterranean area. Both the number of active bouts and the daily activity increased during spring, when females have access to increased food quality, which ensures a faster digestion, and when they may face high energetic requirements owing to reproduction.

Small-scale spatial and temporal interactions among benthic crustaceans and one fish species in the Bay of Biscay

In the summer of 2004, a video survey was carried out in the northern part of the central mud bank (Grande Vasière) of the Bay of Biscay to study the small scale relationship between the dominant crustacean megafauna Nephrops norvegicus, Munida rugosa and Goneplax rhomboides and juvenile hake (Merluccius merluccius). Using a towed body, high-resolution videos were recorded in six sampling sites. Statistical modelling using generalised additive models (GAM) revealed variations in activity patterns for two species. More N. norvegicus were observed outside their burrows at dawn and somewhat at dusk (no observations during night) while G. rhomboides was less observed in the morning. In addition, reduced spatial overlap between G. rhomboides and N. norvegicus suggested reduced competition for food but also space as both are burrowing species. The observed temporal and spatial activity patterns may contribute to regulating assemblage structure as competing species may be actively foraging at different times and locations thus reducing direct competition.

Individual variability in activity patterns of juvenile Atlantic salmon (Salmo salar) in Catamaran Brook, New Brunswick

The activity of juvenile salmonids in streams varies between seasons, age classes, and times of day, but few studies have quantified the magnitude of individual variation in the behaviour of wild individuals. We monitored the activity patterns of 35 young-of-the-year (YOY) (fork length: 25.6–34.6 mm) and eight 1+ (fork length: 68.2–78.7 mm) Atlantic salmon (Salmo salar) over an 8-week summer field season. Age 1+ salmon were more active at night than during the day, whereas YOY fish were almost exclusively active during the day. However, daytime activity did not peak at 16–20 °C, the optimal water temperature range for growth determined in laboratory studies. Rather, the activity of 1+ fish peaked at 21 °C, whereas the activity of YOY fish continued to increase until 23 °C and then leveled off between 23 and 27 °C. There was also considerable individual variability within an age class in how fish responded to environmental variables that was often obscured by the average patterns. In a multiple logistic regression analysis for the activity of the 35 YOY, 18 responded significantly to time of day, 17 to water temperature, and 16 to day of the year. The causes of this individual variability and the consequences for growth and mortality deserve further study.

Overwintering Ecology of Wood Turtles (Glyptemys Insculpta) at the Species' Northern Range Limit

Seasonal variation in activity patterns of reptiles is accompanied by physiological and behavioral adjustments that influence their ecology and life history, and overwinter survival may be an important factor limiting a species' northern range extension. A northern population of Wood Turtles (Glyptemys insculpta) in Ontario, Canada was surveyed in fall 2004, and a subset of adults was radio-tracked every 7–12 days during the winter of 2004–2005 to examine thermal aspects of overwintering. We predicted that Wood Turtles would use hibernacula that protect them from freezing and predation. Temperature data loggers indicated that turtle body temperatures and hibernacula temperatures remained near 0°C from 2 December 2004 until 3 April 2005. During the same period, air temperatures fluctuated substantially and reached a maximum of 10.5°C (on 30 March 2005) and a minimum of less than −40°C (on 21 January 2005) with a mean of −8.3°C. Turtles did not select specific water temperatures nor did they use distinct structures (e.g., root hollows, logjams, and holes in the riverbank) for overwintering but instead rested relatively exposed on the riverbed at a depth of approximately 1 m and at a mean distance of 1.0 m from the riverbank. Surprisingly, turtles made small movements during winter (0.1–10.0 m between radiolocations), typically against the river current and in a direction parallel to the riverbank. Average winter home-range size was 7.1 m2. Our findings raise questions about why turtles move during winter; we suggest possible answers and future lines of investigation to address these questions.

Reducing interscanner variability of activation in a multicenter fMRI study: Controlling for signal-to-fluctuation-noise-ratio (SFNR) differences

Variation in scanner performance will lead to variation in activation patterns in multicenter fMRI studies. The purpose of this investigation was to evaluate the effect of statistically covarying for scanner differences in signal-to-fluctuation-noise-ratio (SFNR) on reducing scanner differences in activation effect size as part of a multicenter fMRI project (FIRST BIRN). For SFNR, “signal” is typically the mean intensity over time and “fluctuation noise” is the temporal standard deviation. Five subjects were sent to 9 centers (10 scanners) and scanned on two consecutive days using a sensorimotor fMRI protocol. High-field (4 T and 3 T) and low-field (1.5 T) scanners from three vendors (GE, Siemens and Picker) were included. The effect size for the detection of neural activation during a sensorimotor task was evaluated as the percent of temporal variance accounted for by our model (percent of variance accounted for, or PVAF). Marked scanner effects were noted for both PVAF as well as SFNR. After covariate adjustment with one of several measures of SFNR, there were dramatic reductions in scanner-to-scanner variations in activation effect size. Variance components analyses revealed 75%–81% reductions in variance due to scanner with this method. Thus, controlling for scanner variation in SFNR may be an effective method to homogenize activation effect sizes in multicenter studies.

Optimization of cardiac resynchronization guided by Doppler echocardiography: haemodynamic improvement and intraindividual variability with different pacing configurations and atrioventricular delays

Cardiac resynchronization therapy (CRT) improves symptoms in heart failure patients with intraventricular conduction delay (IVCD). Different pacing modalities produce variable activation patterns and are likely to result in different haemodynamic changes. The objective of this study was to demonstrate acute haemodynamic changes with different CRT configurations. In 26 patients (left ventricular ejection fraction 22.7+/-6.1%, QRS 176+/-29 ms, New York Heart Association III/IV 18/8), a CRT device was implanted. An optimization procedure was performed including left (LVPEI) and right ventricular pre-ejection intervals, interventricular mechanical delay (IVD), left ventricular filling fraction (FTc), and myocardial performance index (MPI) during left and biventricular pacing with three different atrioventricular (AV) delays. An optimal mode and AV delay were defined. LVPEI changed from 166+/-27 to 139+/-25 ms, IVD from 49+/-19 to 6+/-18 ms, MPI from 0.98+/-0.25 to 0.62+/-0.22, and FTc from 0.42+/-0.08 to 0.51+/-0.08 (P<0.001 for all comparisons). The variability was 39+/-20 ms for LVPEI, 55+/-24 ms for IVD, 0.11+/-0.07 for FTc, and 0.35+/-0.18 for MPI. Optimized resynchronization in heart failure patients with IVCD produces marked acute improvement of the altered cardiac cycle timing. The variability of Doppler parameters with different CRT modalities underlines the necessity of individualized settings and suggests that the patients' benefit may be jeopardized without optimization.

Changes in fMRI activation following rehabilitation of reading and visual processing deficits in subjects with traumatic brain injury

In this case series fMRI was used to examine activation patterns during presentation of a reading comprehension (RC) task in three adult subjects with a history of severe traumatic brain injury (TBI). These subjects received cognitive rehabilitation therapy (CRT) for visual processing and acquired reading deficits. fMRI and neuropsychological testing occurred pre- and post-rehabilitation. The study's objective was to evaluate the neurobiological changes using fMRI occurring with CRT and to compare these results to repeat fMRI in matched control subjects. While improvements in neuropsychological testing occurred post-CRT, diffuse and variable activation patterns in the subjects with TBI were still demonstrated when compared to the control subjects repeat imaging. Multiple networks exist to accomplish the complex task of sentence reading and rehabilitation of the cognitive components of reading, such as visual processing; in subjects with TBI, can alter the activation pattern demonstrated during reading comprehension in subjects many years post-injury. This is the first demonstration of changes in network activation patterns post-CRT in patients with severe, chronic TBI on an fMRI task shown to have imaging stability in a normal control sample.

A muscle-driving model of human walking and estimate of metabolic expenditure on muscles

Current clinical interpretation of dynamic electromyography (EMG) data is usually based on qualitative assessments of muscle timing. Cross-correlation may provide a method for objectively comparing the timing and shape of EMG signals. This study used cross-correlation to compare EMG signals from different walking trials, different test sessions, and different individuals in able-bodied adults. Cross-correlation results (R-values) for different walking trials within a single test session were high, averaging ⩾0.90 for all muscles tested (R=1.0 indicates exact agreement). Cross-correlation values were also high among trials from different test sessions conducted by the same and different examiners (average R⩾0.78 for all muscles). R-values were much more variable when comparing different subjects (average 0.40–0.81, range 0.00–0.91). R-values were lower for the medial hamstrings and rectus femoris compared with the other muscles tested. These results suggest that cross-correlation may be useful for evaluating changes in an individual patient's muscle activation patterns, such as before and after surgery, but not for comparing EMG patterns among different individuals, such as between patients and normative data. This is especially true for biarticular muscles such as the hamstrings and rectus femoris, which may have variable activation patterns and/or increased sensitivity to electrode placement. Cross-correlation may also be useful for identifying appropriate muscles for transfer, identifying “outlier” trials within a test session, and selecting representative EMG curves for a given patient. The advantages of cross-correlation are that it considers shape of the EMG signal in addition to timing and that the assessments it provides are objective, rather than subjective.

Adaptations to humeral torsion in medieval Britain

Adaptations to the humeral torsion angle have been identified in the professional throwing athlete. This movement pattern increases the humeral torsion angle, and also increases the extent of external rotation movements in the dominant, throwing limb when compared with the nondominant limb. The purpose of this paper is to test the hypothesis that the humeral torsion angle is an adaptation to upper limb use. This project examines the humeral torsion angle in a number of medieval British populations, as well as a modern cadaver-based sample. The results identify significant differences in the humeral torsion angle both between and within male (P < 0.001, ANOVA) and female (P < 0.014, ANOVA) populations, although the results are not consistent with expected behavior patterns. Statistically significant differences between males and females within the same site were identified in 2 of the 5 samples examined. The mean level of bilateral asymmetry does not approach that reported for the professional throwing athlete. However, a number of individuals have high levels of asymmetry in excess of that identified in the professional throwing athlete. This analysis demonstrates the need for individual rather than population-based analyses, as the heterogeneity within population samples obscures individual variation in activity patterns. The diversity within British medieval society and a lack of specific known behaviors prevent further identification of the functional significance of the humeral torsion angle within the archaeological record examined here.