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Cross-mating between Malaysian strains of Aedes aegypti and Aedes albopictus in the laboratory

Nazni WA, Lee HL, Dayang HA, Azahari AH

Southeast Asian J Trop Med Public Health, 2009 Jan;40(1):40-6.
PMID: 19323032

Reciprocal and homologous mating experiments between Malaysian Aedes aegypti and Aedes albopictus mosquitoes were conducted in the laboratory. Two methods were employed, namely an artificial mating technique and a natural cage mating technique. The study demonstrated there exists a strong reproductive isolation between Ae. aegypti and Ae. albopictus. Insemination occurred in cross-mating experiments between Ae. aegypti females and Ae. albopictus males and also between Ae. albopictus females and Ae. aegypti males. Cross mating between Ae. aegypti females and Ae. albopictus males produced more eggs than that between Ae. albopictus females and Ae. aegypti males with both artificial mating and natural cage mating techniques. The matings did not result in the production of viable eggs by the females. No embryonation of these eggs was observed when the eggs were bleached. With homologous mating Aedes aegypti produced significantly greater numbers of eggs compared to Aedes albopictus mosquitoes, and all the eggs hatched successfully.

Matched MeSH terms: Aedes/physiology*; Insemination/physiology*; Oviposition/physiology*; Sexual Behavior, Animal/physiology*
Fecundity, embryonic and ovarian development of blue swimming crab, Portunus pelagicus (Linnaeus, 1758) in coastal water of Johor, Malaysia

Ikhwanuddin M, Azra MN, Siti-Aimuni H, Abol-Munafi AB

Pak J Biol Sci, 2012 Aug 01;15(15):720-8.
PMID: 24171257

Blue swimming crab, Portunus pelagicus is widely study and research throughout the Indo-West Pacific, but little is known of its reproductive biology in Malaysia. The present study describes the fecundity, embryonic development and ovarian development stages of the P. pelagicus from Johor coastal water, Malaysia. Carapace width range of berried crabs sampled was from 9.64 to 13.32 cm, while the body weight range was from 75 to 235 g. The mean number of egg produced by females in different sizes ranged from 105443.333 +/- 35448.075 per eggs batch. Mean egg size during embryonic development at stage 1 was 0.307 +/- 0.037, while 0.386 +/- 0.039 and 0.396 +/- 0.033 for stage 2 and stage 3, respectively. Study showed that there was significant (p < 0.05) relationship between the number of eggs and carapace width/body weight. Mean diameter oocyte during ovarian development at stage 1 was 97.732 +/- 12.391 while for stage 2 was 149.516 +/- 23.287. Stage 3 showed increasingly of size with mean diameter was 158.506 +/- 27.616 and 181.013 +/- 24.339 for stage 4.

Matched MeSH terms: Brachyura/physiology*; Fertility/physiology; Ovary/physiology; Reproduction/physiology
Fulltext Relationship between retinal blood flow and arterial oxygen

Cheng RW, Yusof F, Tsui E, Jong M, Duffin J, Flanagan JG, et al.

J Physiol, 2016 Feb 01;594(3):625-40.
PMID: 26607393 DOI: 10.1113/JP271182

KEY POINTS: Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2. Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen. The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function. This model demonstrates that the resting tonus of the vessels is at the mid-point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a PETCO2 of 32-37 mmHg but being limited below this threshold. Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end-tidal partial pressure of oxygen (PETCO2) ranging from 40-500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content for all stages of hypoxia used in the present study but can no longer compensate below a PETCO2 of 32-37 mmHg. These vessels have a great vascular range of adjustment, increasing diameter (8.5% arteriolar and 21% total venous area) with hypoxia (40 mmHg P ETC O2; P < 0.001) and decreasing diameter (6.9% arteriolar and 23% total venous area) with hyperoxia (500 mmHg PETCO2; P < 0.001) to the same extent. This indicates that the resting tonus is near the mid-point of the adjustment ranges at resting PaO2 where sensitivity is maximum.

Matched MeSH terms: Oxygen/physiology*; Regional Blood Flow/physiology*; Retina/physiology*; Retinal Vessels/physiology*
Evaluation of Shoulder and Knee Isokinetic Strength Profile Among Elite Adolescent Badminton Players

Zulfikri N, Selvanayagam VS, Yusof A

J Sport Rehabil, 2021 Jan 19;30(5):717-724.
PMID: 33465761 DOI: 10.1123/jsr.2019-0483

CONTEXT: Badminton continues to be a highly competitive sport where training is introduced at an early age and load has intensiﬁed. This exposes players to a greater risk of injuries, in particular when assessing related training outcomes such as strength, agonist-antagonist ratio, and bilateral deﬁcit among adolescents where age- and sex-associated growth and development should be considered.
OBJECTIVE: To evaluate strength proﬁle of the upper and lower limbs among adolescent elite Malaysian badminton players.
DESIGN: Cross-sectional study.
SETTING: Laboratory.
PARTICIPANTS: Forty-eight asymptomatic athletes (24 males and 24 females) were grouped into early and late adolescence (13-14 y old and 15-17 y old, respectively).
MAIN OUTCOME MEASURE(S): Strength (absolute and normalized) of the external/internal rotators of the shoulder and ﬂexor/extensor of the knee and strength derivatives, conventional strength ratio (CSR), dynamic control ratio (DCR), and bilateral deﬁcits were measured.
RESULTS: Males showed greater strength in all strength indices (P < .05). The older group had greater strength compared to younger for most of the upper and lower limb indices (P < .05); these effects diminished when using normalized data. For females, there was no age group effect in the shoulder and knee strength. All players displayed lower shoulder and knee normative values for CSR and DCR. Dominant and non-dominant knee strength were comparable between sex and age groups.
CONCLUSIONS: For males, growth and maturation had a greater contribution to strength gained compared to training, whereas for females, growth, maturation, and training did not improve strength. The normalized data indicated that training did not improve all indices measured apart from external rotator strength in females. All players also displayed lower normative values of CSR and DCR. These results suggest that training in elite adolescent Malaysian badminton players lacks consideration of strength gain and injury risk factors.

Matched MeSH terms: Knee Joint/physiology*; Functional Laterality/physiology; Shoulder Joint/physiology*; Racquet Sports/physiology*; Rotator Cuff/physiology; Muscle, Skeletal/physiology; Adolescent Development/physiology; Muscle Strength/physiology*; Physical Conditioning, Human/physiology
Fulltext A cardiovascular mathematical model of graded head-up tilt

Lim E, Chan GS, Dokos S, Ng SC, Latif LA, Vandenberghe S, et al.

PLoS One, 2013;8(10):e77357.
PMID: 24204817 DOI: 10.1371/journal.pone.0077357

A lumped parameter model of the cardiovascular system has been developed and optimized using experimental data obtained from 13 healthy subjects during graded head-up tilt (HUT) from the supine position to [Formula: see text]. The model includes descriptions of the left and right heart, direct ventricular interaction through the septum and pericardium, the systemic and pulmonary circulations, nonlinear pressure volume relationship of the lower body compartment, arterial and cardiopulmonary baroreceptors, as well as autoregulatory mechanisms. A number of important features, including the separate effects of arterial and cardiopulmonary baroreflexes, and autoregulation in the lower body, as well as diastolic ventricular interaction through the pericardium have been included and tested for their significance. Furthermore, the individual effect of parameter associated with heart failure, including LV and RV contractility, baseline systemic vascular resistance, pulmonary vascular resistance, total blood volume, LV diastolic stiffness and reflex gain on HUT response have also been investigated. Our fitted model compares favorably with our experimental measurements and published literature at a range of tilt angles, in terms of both global and regional hemodynamic variables. Compared to the normal condition, a simulated congestive heart failure condition produced a blunted response to HUT with regards to the percentage changes in cardiac output, stroke volume, end diastolic volume and effector response (i.e., heart contractility, venous unstressed volume, systemic vascular resistance and heart rate) with progressive tilting.

Matched MeSH terms: Blood Pressure/physiology; Cardiac Output/physiology; Heart/physiology*; Heart Rate/physiology; Hemodynamics/physiology; Myocardial Contraction/physiology; Posture/physiology*; Pressoreceptors/physiology*; Pulmonary Circulation/physiology; Stroke Volume/physiology; Vascular Resistance/physiology; Baroreflex/physiology
Onset of labour

Chong HL, Ong HC, Ang LT

Med J Malaysia, 1974 Sep;29(1):44-53.
PMID: 4282630
Matched MeSH terms: Adrenal Cortex Hormones/physiology; Amniotic Fluid/physiology; Estrogens/physiology; Fetus/physiology; Hypothalamus/physiology; Oxytocin/physiology; Placental Lactogen/physiology; Progesterone/physiology; Prostaglandins E/physiology; Prostaglandins F/physiology; Gonadal Steroid Hormones/physiology*; Uterus/physiology
Fulltext Leukemia inhibitory factor: roles in embryo implantation and in nonhormonal contraception

Salleh N, Giribabu N

ScientificWorldJournal, 2014;2014:201514.
PMID: 25152902 DOI: 10.1155/2014/201514

Leukaemia inhibitory factor (LIF) plays an indispensible role in embryo implantation. Aberrant LIF production is linked to implantation failure. LIF regulates multiple processes prior to and during implantation such as uterine transformation into a receptive state, decidualization, blastocyst growth and development, embryo-endometrial interaction, trophoblast invasion, and immune modulation. Due to its critical role, LIF has been a target for a nonhormonal contraception. In this review, we summarize up-to-date information on the role of LIF in implantation and its role in contraception.

Matched MeSH terms: Blastocyst/physiology; Decidua/physiology; Leukocytes/physiology; Embryo Implantation/physiology*; Trophoblasts/physiology; Uterus/physiology
Strength and fatigue of lumbar extensor muscles in older adults

Ajit Singh DK, Bailey M, Lee R

Muscle Nerve, 2011 Jul;44(1):74-9.
PMID: 21488056 DOI: 10.1002/mus.21998

Loss of lumbar extensor muscle strength and fatigue resistance may contribute to functional disability.

Matched MeSH terms: Aging/physiology*; Lumbosacral Region/physiology; Muscle Contraction/physiology; Muscle, Skeletal/physiology*; Muscle Fatigue/physiology*; Muscle Strength/physiology*
Ethnic differences in thermoregulatory responses during resting, passive and active heating: application of Werner's adaptation model

Lee JY, Wakabayashi H, Wijayanto T, Hashiguchi N, Saat M, Tochihara Y

Eur J Appl Physiol, 2011 Dec;111(12):2895-905.
PMID: 21437607 DOI: 10.1007/s00421-011-1912-5

For the coherent understanding of heat acclimatization in tropical natives, we compared ethnic differences between tropical and temperate natives during resting, passive and active heating conditions. Experimental protocols included: (1) a resting condition (an air temperature of 28°C with 50% RH), (2) a passive heating condition (28°C with 50% RH; leg immersion in a hot tub at a water temperature of 42°C), and (3) an active heating condition (32°C with 70% RH; a bicycle exercise). Morphologically and physically matched tropical natives (ten Malaysian males, MY) and temperate natives (ten Japanese males, JP) participated in all three trials. The results saw that: tropical natives had a higher resting rectal temperature and lower hand and foot temperatures at rest, smaller rise of rectal temperature and greater temperature rise in bodily extremities, and a lower sensation of thirst during passive and active heating than the matched temperate natives. It is suggested that tropical natives' homeostasis during heating is effectively controlled with the improved stability in internal body temperature and the increased capability of vascular circulation in extremities, with a lower thirst sensation. The enhanced stability of internal body temperature and the extended thermoregulatory capability of vascular circulation in the extremities of tropical natives can be interpreted as an interactive change to accomplish a thermal dynamic equilibrium in hot environments. These heat adaptive traits were explained by Wilder's law of initial value and Werner's process and controller adaptation model.

Matched MeSH terms: Adaptation, Physiological/physiology; Blood Circulation/physiology; Body Temperature/physiology*; Body Temperature Regulation/physiology*; Rest/physiology*; Exercise/physiology*
Acute effect of static and dynamic stretching on hip dynamic range of motion during instep kicking in professional soccer players

Amiri-Khorasani M, Abu Osman NA, Yusof A

J Strength Cond Res, 2011 Jun;25(6):1647-52.
PMID: 21358428 DOI: 10.1519/JSC.0b013e3181db9f41

The purpose of this study was to examine the effects of static and dynamic stretching within a pre-exercise warm-up on hip dynamic range of motion (DROM) during instep kicking in professional soccer players. The kicking motions of dominant legs were captured from 18 professional adult male soccer players (height: 180.38 ± 7.34 cm; mass: 69.77 ± 9.73 kg; age: 19.22 ± 1.83 years) using 4 3-dimensional digital video cameras at 50 Hz. Hip DROM at backward, forward, and follow-through phases (instep kick phases) after different warm-up protocols consisting of static, dynamic, and no-stretching on 3 nonconsecutive test days were captured for analysis. During the backswing phase, there was no difference in DROM after the dynamic stretching compared with the static stretching relative to the no-stretching method. There was a significant difference in DROM after the dynamic stretching compared with the static stretching relative to the no-stretching method during (a) the forward phase with p < 0.03, (b) the follow-through phase with p < 0.01, and (c) all phases with p < 0.01. We concluded that professional soccer players can perform a higher DROM of the hip joint during the instep kick after dynamic stretching incorporated in warm-ups, hence increasing the chances of scoring and injury prevention during soccer games.

Matched MeSH terms: Hip/physiology*; Soccer/physiology*; Exercise/physiology; Range of Motion, Articular/physiology*; Muscle, Skeletal/physiology; Athletic Performance/physiology*
Biomechanical responses of thigh and lower leg during 10 consecutive soccer instep kicks

Amiri-Khorasani M, Abu Osman NA, Yusof A

J Strength Cond Res, 2011 Apr;25(4):1177-81.
PMID: 20838249 DOI: 10.1519/JSC.0b013e3181d6508c

This study investigated the number of trials necessary to obtain optimal biomechanical responses in 10 consecutive soccer instep kicks. The kicking motions of dominant legs were captured from 5 experienced and skilled adult male soccer players (height: 184.60 ± 4.49 cm; mass: 80 ± 4.24 kg; and age: 25.60 ± 1.14 years) using a 3D infrared high-speed camera at 200 Hz. Some of the important kinematics and kinetics parameters are maximum thigh angular velocity, maximum lower leg angular velocity, maximum of thigh moment, maximum lower leg moment at forward and impact phases, and finally maximum ball velocity after impact selected to be analyzed. There was a significant decrease of ball velocity between the first and the fifth kick and the subsequent kicks. Similarly, the lower leg angular velocity showed a significant decrease after the fifth kick and thereafter. Compared with the first kick, the thigh angular velocity has been shown to decrease after the sixth kick and thereafter, and the thigh moment result of the sixth kick was significantly lower when compared with the first kick. Moreover, the lower leg moment result of the fourth kick was significantly lower in comparison with the first kick. In conclusion, it seems that 5 consecutive kicks are adequate to achieve high kinematics and kinetics responses and selecting more than 5 kicks does not result in any high biomechanical responses for analysis.

Matched MeSH terms: Biomechanical Phenomena/physiology; Leg/physiology*; Soccer/physiology*; Thigh/physiology*; Muscle, Skeletal/physiology; Athletic Performance/physiology*
Anthropometric and physiological profiles of sepak takraw players

Jawis MN, Singh R, Singh HJ, Yassin MN

Br J Sports Med, 2005 Nov;39(11):825-9; discussion 825-9.
PMID: 16244191

OBJECTIVES: Anthropometric and physiological profiles of national sepak takraw players were determined.
METHODS: Thirty nine players, specialising in the three playing positions (tekong/server, feeder, and killer/spiker) were divided into three age categories of under 15 (U15), under 18 (U18), and under 23 (U23) years of age. Height, weight, percent body fat (%bf), maximum oxygen consumption (Vo(2max)), range of motion (ROM), back and leg strength, and heart rate, for the estimation of oxygen consumption during matches, were recorded. Statistical analysis was performed using one way ANOVA for independent measurements and data are presented as mean+/-standard deviation.
RESULTS: The U23 players were significantly taller and heavier with significantly better ROM of the neck, trunk, and ankle joints and back and leg strength than the U15 players. No significant difference was found in %bf between the three age categories. Mean maximum heart rate during exercise was significantly higher in the U15 group when compared to the U18 and U23 groups (p<0.05). Mean Vo2max was similar between the three groups. Estimated oxygen consumption during matches was 69.1%, 68.5%, and 56.4% of Vo2max in the killer, tekong, and the feeder groups, respectively.
CONCLUSIONS: The mean height, body weight, and cardiopulmonary capacities of the players were within the Malaysian population norms, but were somewhat lower than those of players of other court games from other countries. %bf was also lower in these players. This study provides the much needed anthropometric and physiological data of sepak takraw players for further development of this sport.

Matched MeSH terms: Body Height/physiology; Body Weight/physiology; Heart Rate/physiology; Oxygen Consumption/physiology; Sports/physiology*; Range of Motion, Articular/physiology
Fulltext Mixed Mating System Are Regulated by Fecundity in Shorea curtisii (Dipterocarpaceae) as Revealed by Comparison under Different Pollen Limited Conditions

Tani N, Tsumura Y, Fukasawa K, Kado T, Taguchi Y, Lee SL, et al.

PLoS One, 2015;10(5):e0123445.
PMID: 25938512 DOI: 10.1371/journal.pone.0123445

The maintenance of mixed mating was studied in Shorea curtisii, a dominant and widely distributed dipterocarp species in Southeast Asia. Paternity and hierarchical Bayesian analyses were used to estimate the parameters of pollen dispersal kernel, male fecundity and self-pollen affinity. We hypothesized that partial self incompatibility and/or inbreeding depression reduce the number of selfed seeds if the mother trees receive sufficient pollen, whereas reproductive assurance increases the numbers of selfed seeds under low amounts of pollen. Comparison of estimated parameters of self-pollen affinity between high density undisturbed and low density selectively logged forests indicated that self-pollen was selectively excluded from mating in the former, probably due to partial self incompatibility or inbreeding depression until seed maturation. By estimating the self-pollen affinity of each mother tree in both forests, mother trees with higher amount of self-pollen indicated significance of self-pollen affinity with negative estimated value. The exclusion of self-fertilization and/or inbreeding depression during seed maturation occurred in the mother trees with large female fecundity, whereas reproductive assurance increased self-fertilization in the mother trees with lower female fecundity.

Matched MeSH terms: Fertility/physiology*; Pollen/physiology*; Reproduction/physiology; Seeds/physiology; Trees/physiology; Dipterocarpaceae/physiology*
Iliotibial band tension affects patellofemoral and tibiofemoral kinematics

Merican AM, Amis AA

J Biomech, 2009 Jul 22;42(10):1539-1546.
PMID: 19481211 DOI: 10.1016/j.jbiomech.2009.03.041

The iliotibial band (ITB) has an important role in knee mechanics and tightness can cause patellofemoral maltracking. This study investigated the effects of increasing ITB tension on knee kinematics. Nine fresh-frozen cadaveric knees had the components of the quadriceps loaded with 175 N. A Polaris optical tracking system was used to acquire joint kinematics during extension from 100 degrees to 0 degrees flexion. This was repeated after the following ITB loads: 30, 60 and 90 N. There was no change with 30 N load for patellar translation. On average, at 60 and 90 N, the patella translated laterally by 0.8 and 1.4mm in the mid flexion range compared to the ITB unloaded condition. The patella became more laterally tilted with increasing ITB loads by 0.7 degrees, 1.2 degrees and 1.5 degrees for 30, 60 and 90 N, respectively. There were comparable increases in patellar lateral rotation (distal patella moves laterally) towards the end of the flexion cycle. Increased external rotation of the tibia occurred from early flexion onwards and was maximal between 60 degrees and 75 degrees flexion. The increase was 5.2 degrees, 9.5 degrees and 13 degrees in this range for 30, 60 and 90 N, respectively. Increased tibial abduction with ITB loads was not observed. The combination of increased patellar lateral translation and tilt suggests increased lateral cartilage pressure. Additionally, the increased tibial external rotation would increase the Q angle. The clinical consequences and their relationship to lateral retinacular releases may be examined, now that the effects of a tight ITB are known.

Matched MeSH terms: Fascia/physiology; Femur/physiology; Ilium/physiology; Knee Joint/physiology*; Patella/physiology; Tibia/physiology
Changes in Muscle Activity in Response to Assistive Force during Isometric Elbow Flexion

Loh PY, Hayashi K, Nasir N, Muraki S

J Mot Behav, 2020;52(5):634-642.
PMID: 31571525 DOI: 10.1080/00222895.2019.1670128

This study investigated the muscle activity and force variability in response to perturbation of assistive force during isometric elbow flexion. Sixteen healthy right-handed young men (age: 22.0 ± 1.1 years; height: 171.9 ± 4.8 cm; weight 68.4 ± 11.2 kg) were recruited and the muscle activity of biceps brachii and triceps brachii were assessed using surface electromyography. Workload force and assistive force applied on isometric elbow flexion significantly affected the changes in both biceps and triceps muscle activities. A higher assistive force was shown to result in reduced biceps muscle activity compared to the unassisted period. In contrast, the efficiency of the assistive force acting on the biceps decreased as the assistive force increased. In general, the force variability of the biceps muscle remained approximately the same at lower workload force conditions than that at higher workload force conditions. In conclusion, higher assistive force may not yield a higher performance efficiency in human-assistive force interaction.

Matched MeSH terms: Elbow/physiology*; Isometric Contraction/physiology*; Muscle Contraction/physiology; Range of Motion, Articular/physiology; Muscle, Skeletal/physiology*; Hamstring Muscles/physiology
Analysis of the crosstalk in mechanomyographic signals along the longitudinal, lateral and transverse axes of elbow flexor muscles during sustained isometric forearm flexion, supination and pronation exercises

Talib I, Sundaraj K, Lam CK

J Musculoskelet Neuronal Interact, 2020 06 01;20(2):194-205.
PMID: 32481235

OBJECTIVE: To analyse the influence of muscle fibre axis on the degree of crosstalk in mechanomyographic (MMG) signals during sustained isometric forearm flexion, pronation and supination exercises performed at 80% maximum voluntary contraction (MVC) at an elbow joint angle of 90°.
METHODS: MMG signals in longitudinal, lateral and transverse directions of muscle fibres were recorded from the elbow flexors of twenty-five male subjects using triaxial accelerometers. Cross-correlation coefficients were used to quantify the degree of crosstalk in all nine possible pairs of fibre axes, all muscle pairs and all exercises.
RESULTS: MMG root mean square (RMS) was statistically significant among the fibre axes (p<0.05, η2=0.17- 0.34) except for biceps brachii and brachioradialis in supination and brachialis in flexion. Overall mean crosstalk values in the three muscle pairs (biceps brachii & brachialis, brachialis & brachioradialis and brachioradialis & biceps brachii) were found to be 6.09-52.17%, 4.01-61.42% and 2.16-51.85%, respectively. Crosstalk values showed statistical significance among all nine axes pairs (p<0.05, η2=0.16-0.51) except for biceps brachii & brachialis during pronation. The transverse axes pair generated the lowest mean crosstalk values (2.16-9.14%).
CONCLUSION: MMG signals recorded using accelerometers from the transverse axes of muscle fibres in the elbow flexors are unique and yield the least amount of crosstalk.

Matched MeSH terms: Forearm/physiology; Isometric Contraction/physiology*; Pronation/physiology*; Supination/physiology*; Exercise/physiology; Muscle, Skeletal/physiology*
The Time Course of Activity within the Dorsal and Rostral-Ventral Anterior Cingulate Cortex in the Emotional Stroop Task

Feroz FS, Leicht G, Steinmann S, Andreou C, Mulert C

Brain Topogr, 2017 Jan;30(1):30-45.
PMID: 27659288 DOI: 10.1007/s10548-016-0521-3

Growing evidence from neuroimaging studies suggest that emotional and cognitive processes are interrelated. Anatomical key structures in this context are the dorsal and rostral-ventral anterior cingulate cortex (dACC and rvACC). However, up to now, the time course of activations within these regions during emotion-cognition interactions has not been disentangled. In the present study, we used event-related potentials (ERP) and standardized low-resolution electromagnetic tomography (sLORETA) region of interest (ROI) source localization analyses to explore the time course of neural activations within the dACC and rvACC using a modified emotional Stroop paradigm. ERP components related to Stroop conflict (N200, N450 and late negativity) were analyzed. The time course of brain activations in the dACC and rvACC was strikingly different with more pronounced initial responses in the rvACC followed by increased dACC activity mainly at the late negativity window. Moreover, emotional valence modulated the earlier N450 stage within the rvACC region with higher neural activations in the positive compared to the negative and neutral conditions. Emotional arousal modulated the late negativity stage; firstly in the significant arousal × congruence ERP effect and then the significant higher current density in the low arousal condition within the dACC. Using sLORETA source localization, substantial differences in the activation time courses in the dACC and rvACC could be found during the emotional Stroop task. We suggest that during late negativity, within the dACC, emotional arousal modulated the processing of response conflict, reflected in the correlation between the ex-Gaussian µ and the current density in the dACC.

Matched MeSH terms: Arousal/physiology; Attention/physiology*; Cognition/physiology; Emotions/physiology*; Evoked Potentials/physiology*; Gyrus Cinguli/physiology*
Fulltext Rubber hands in space: the role of distance and relative position in the rubber hand illusion

Kalckert A, Perera AT, Ganesan Y, Tan E

Exp Brain Res, 2019 Jul;237(7):1821-1832.
PMID: 31079236 DOI: 10.1007/s00221-019-05539-6

The rubber hand illusion (RHI) is a perceptual phenomenon in which participants experience ownership over a fake model hand through synchronous visuotactile stimulation. Several studies have shown that the illusion occurs only when both hands are in close proximity to each other. In the present study, we systematically examined the role of relative position (lateral, distal) and distance (13-75 cm) of the model hand (with respect to participants' real hand) on illusion experience across both lateral and distal positions. Furthermore, we also compared different facets of the subjective illusion experience; the experience of the model hand being part of one's body (i.e., ownership) and the perceptual fusion of vision and touch (i.e., referral of touch). In two experiments we observed indications for a stronger illusion experiences in distal compared to lateral positions of identical distances, indicating that the illusory effects may vary as a function of the relative position of the hand. Our results also showed that manipulations of distance differently modulated both facets of the illusion. While ownership was restricted to near distances, referral of touch sensations remained stable at farther distances. These results are interpreted in relation to variations in sensory weighting across different planes.

Matched MeSH terms: Distance Perception/physiology*; Hand/physiology*; Illusions/physiology*; Proprioception/physiology*; Space Perception/physiology; Touch Perception/physiology*
Effects of white noise on word recall performance and brain activity in healthy adolescents with normal and low auditory working memory

Othman E, Yusoff AN, Mohamad M, Abdul Manan H, Abd Hamid AI, Giampietro V

Exp Brain Res, 2020 Apr;238(4):945-956.
PMID: 32179941 DOI: 10.1007/s00221-020-05765-3

The present study examined the impact of white noise on word recall performance and brain activity in 40 healthy adolescents, split in two groups (normal and low) depending on their auditory working memory capacity (AWMC). Using functional magnetic resonance imaging, participants performed a backward recall task under four different signal-to-noise ratio (SNR) conditions: 15, 10, 5, and 0-dB SNR. Behaviorally, normal AWMC individuals scored significantly higher than low AWMC individuals across noise levels. Whole-brain analyses showed brain activation not to be statistically different between groups across noise levels. In the normal group, a significant positive relationship was found between performance and number of activated voxels in the right superior frontal gyrus. In the low group, significant positive correlations were found between performance and number of activated voxels in left superior frontal gyrus, left inferior frontal gyrus, and left anterior cingulate cortex. These findings suggest that the strategic structure involved in the enhancement of AWM performance may differ in normal and low AWMC individuals.

Matched MeSH terms: Attention/physiology*; Auditory Perception/physiology*; Gyrus Cinguli/physiology*; Memory, Short-Term/physiology*; Mental Recall/physiology*; Prefrontal Cortex/physiology*
Age- and size-related changes in physiological characteristics and chemical composition of Acer pseudoplatanus and Fraxinus excelsior trees

Abdul-Hamid H, Mencuccini M

Tree Physiol, 2009 Jan;29(1):27-38.
PMID: 19203930 DOI: 10.1093/treephys/tpn001

Forest growth is an important factor both economically and ecologically, and it follows a predictable trend with age. Generally, growth accelerates as canopies develop in young forests and declines substantially soon after maximum leaf area is attained. The causes of this decline are multiple and may be linked to age- or size-related processes, or both. Our objective was to determine the relative effects of tree age and tree size on the physiological attributes of two broadleaf species. As age and size are normally coupled during growth, an approach based on grafting techniques to separate the effects of size from those of age was adopted. Genetically identical grafted seedlings were produced from scions taken from trees of four age classes, ranging from 4 to 162 years. We found that leaf-level net photosynthetic rate per unit of leaf mass and some other leaf structural and biochemical characteristics had decreased substantially with increasing size of the donor trees in the field, whereas other gas exchange parameters expressed on a leaf area basis did not. In contrast, these parameters remained almost constant in grafted seedlings, i.e., scions taken from donor trees with different meristematic ages show no age-related trend after they were grafted onto young rootstocks. In general, the results suggested that size-related limitations triggered the declines in photosynthate production and tree growth, whereas less evidence was found to support a role of meristematic age.

Matched MeSH terms: Carbon Dioxide/physiology; Nitrogen/physiology; Photosynthesis/physiology*; Plant Leaves/physiology; Acer/physiology*; Fraxinus/physiology*

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