Effect of age on the orientation of attention: effect of changing the interval between signal and stimulus]

The purpose of the experiment was to examine the effect of aging on spatial attention. One of two possible locations, horizontally arranged, was cued. The subject had to respond to the onset of a visual stimulus, wherever it appeared. The task demand was to orient attention to the stimulated location before producing a response, or to reorient it if the position is not the cued one. Younger and older adults showed the same response pattern, despite the overall slowing down of response presented by the latter.     

Effect of age on the orientation of the auricular activation vector in pig

The effects of cardiac maturation on the orientation of the auricular activation mean vectors (AP and SAP) in Landrace X White Belgian pigs has been analyzed. The magnitudes of AP and SAP vectors undergo a significant increase between 5 and 20 days of age. On the contrary, physical maturation does not appear to have any effect on the sequence of auricular activation in pigs, since in all the age groups analyzed, the same orientation for P vectors on the horizontal plane and in space was maintained. Both vectors indicated that the auricular activation front was predominantly directed towards the left, caudally and ventrally. It should be noted that in a high percentage of individuals of 1 to 5 days of age, the auricular activation vector goes towards the left and cranially.     

Effects of age and gender on the location and orientation of the foramen magnum in rhesus macaques (Macaca mulatta)

Endocasts from 378 rhesus macaque skulls from the Cayo Santiago skeletal collection were measured to determine the effects of age and gender on the position and orientation of the foramen magnum. The foramen magnum migrates from a rostral to a caudal position and its angle changes during postnatal development. The angles and relative positions of the foramen magnum are similar for both genders of infants and for both genders of adults. However, analyses of linear response and plateau (LRP) functions reveal significant differences between males and females in the timing of reorientation of the angle and migration of the foramen magnum. The mean adult angle and relative position of the foramen magnum are reached by 4.7 years in females, but they do not achieve their adult values until 7.1 years in males. A similar pattern is observed for the brainstem region of the basicranium. Mean adult lengths of the brainstem region are reached at 5.2 years in females and 7.1 years in males. The relationships between cranial capacity, the growth pattern of the brainstem, and the pattern of change for the angle and the relative position of the foramen magnum are examined. Quantification of the effects of age and gender on the location of the foramen magnum in a large sample of endocasts from one species of higher primate has potential implications for research on human development, and for interpretation of juvenile specimens in the hominid fossil record.     

Facilitating and inhibiting effects of the orientation of attention using peripheral cues]

The attentional field resulting from the presentation of peripheral cues; which were either informative or non informative about the position of the imperative stimulus, was studied. Different time intervals between cue and stimulus (120, 300, 600 ms) were used. The results showed facilitation of the response with the informative cue and inhibition with the non informative cue. This happened for the longest cue-stimulus intervals and when the position of the cue and the position of the stimulus were congruent. Also order of cue presentation (i.e., either informative followed by the non informative cue or vice versa) proved important in producing facilitatory and inhibitory effects.     

Effects of age on antibody affinity maturation

The elderly are more susceptible to infectious diseases. Mortality and morbidity from infections increase sharply over the age of 65 years. At the same time, the efficacy of vaccinations in the elderly is decreased. The elderly also have an increased incidence of cancer and inflammatory diseases. All the above indicate an age-related dysregulation of the immune system. Evidence suggests that the change in the humoral immune response with age is a qualitative rather than a quantitative one, i.e. it is the affinity and specificity of the antibody that changes, rather than the quantity of antibody produced. There are a number of possible causes of this failure, one of which is a defect in the mechanism of hypermutation of immunoglobulin genes. We have studied individual clonal responses within germinal centres of spleen and Peyer's patches in young and old patient groups. Our results indicate that there is no difference in the actual mechanism of hypermutation with age. There are, however, differences that are due either to a change in selection processes or to a change in the founder cells available for activation.     

Effects of age on regional residual volume

Forty-one normal non-smokers between the ages of 20 and 80 were studied to determine if the increased residual volume, known to occur with aging, results from increased residual volume throughout, or only in specific regions of the lung. The subjects were dividied into groups consisting of 20-29, 30-39, 40-49, 50-69, and 70+ yr. Measurements of regional residual volume to regional total lung capacity ratio (RVr/TLCr) were made using zenon-133 and a multidetector analysis system in which five zones (from top to bottom) were analyzed in each lung. Closing volume was also measured. The subjects were in the sitting position for all studies. The results showed regardless of age, the RVr/TLCr was higher at the top than at the bottom of the lung. In addition, the ratio of upper to lower RVr/TLCr was not significantly different between any of the age groups. The results can be explained if airways throughout the lung close at higher volumes as age increases, or if altered emptying sequences within regions occur due to retarded emptying of highly compliant lung regions.     

Effects of hostplant age on phytophagous insects

In Colorado beetle females fed with physiologically aged potato leaves, an inhibition or even a standstill of reproduction occurs, followed by diapause.In such beetles, the volume of the corpora allata is reduced and the medial cerebral neurosecretory cells do not transport their neurosecretory material. In feeding tests, it is shown that the beetle can detect the age of its hostplant.

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Zusammenfassung Wenn weiblichen Kartoffelkäfern zwei Arten bevorzugter Wirtspflanzen zur Verfügung stehen, ändert sich ihr Wirtswahlverhalten mit dem Ansteigen der Temperatur, während das nicht der Fall ist, wenn abgelehnte mit angenommenen Pflanzen verglichen werden.Die Käfer können zwischen alten und jungen Blättern bevorzugter Wirtspflanzen unterscheiden.Bei Kartoffelkäfern, die mit physiologisch gealtertem Laub gefüttert werden, tritt eine Hemmung oder sogar ein völliger Stillstand der Reproduktion ein, worauf eine Diapause folgt. Es scheint, daß die Corpora allata beeinflußt werden und aufhören zu arbeiten; die Käfer zeigen histologisch die charakteristischen Anzeichen diapausierender Käfer genauso wie hungernde Käfer: einen völligen Stillstand des Transportes von Neurosekret und eine dichte Anhäufung neurosekretorischen Materials innerhalb der Zellen. Nachfolgende Nahrungsaufnahme der hungernden Käfer bewirkt den Transport neurosekretorischen Materials entlang der Neurosekretbahnen und die Dispersion desselben innerhalb des Zellplasmas.Es scheint also, daß die jahreszeitlichen Veränderungen im Zustand der Wirtspflanze dem neuro-endokrinen System angezeigt werden und für die Nahrungswahl sowie für die Synchronisation von Bedeutung sind.

     

Effects of exogenous melatonin on sun-compass orientation of homing pigeons

Experiments were performed to test whether melatonin plays a role in sun-compass orientation of homing pigeons. Birds were kept for a period of time in dim continuous light (LL) or in artificial light-dark (LD) cycles and then released under the sun from unfamiliar sites. Control birds in dim LL were oriented homeward in all cases. Birds with melatonin implants in LD were capable of a correct use of the sun compass at release. Birds with melatonin implants in dim LL, on the contrary, performed very poorly in orientation. The present results demonstrate for the first time that melatonin is involved in the control of the circadian rhythms underlying sun-compass orientation in birds.     

Effects on discrimination performance of selective attention to tactile features

This study examined selective attention to tactile dimensions by combining a selective cueing paradigm with a test of integrality. In Experiment 1, subjects selectively attended to changes in the frequency or duration of pairs of vibrotactile stimuli and identified the higher frequency or longer duration stimulus. In Experiment 2, using surface gratings in an identical experimental procedure, subjects identified the rougher or longer duration stimulus. In both experiments, greater performance accuracy was found on trials where the cue correctly (valid) predicted the changing dimension, vs incorrectly (invalid) cued or no-cue (neutral) trials. More errors on the invalidly vs neutrally cued trials show the cost of focal attention. Increases in performance on validly vs neutrally cued trials show a benefit of filtering irrelevant stimuli in the cued conditions. Results effectively demonstrate focal attention to tactile features. Tests of integrality, in terms of the effects of correlated change in both dimensions, showed no redundancy gain for either vibrotactile or grating tasks, suggesting that frequency and roughness are separable from stimulus duration. Interference of negative correlated change for frequency but not roughness discriminations may be explained by differences in task difficulty.     

Effects on discrimination performance of selective attention to tactile features

This study examined selective attention to tactile dimensions by combining a selective cueing paradigm with a test of integrality. In Experiment 1, subjects selectively attended to changes in the frequency or duration of pairs of vibrotactile stimuli and identified the higher frequency or longer duration stimulus. In Experiment 2, using surface gratings in an identical experimental procedure, subjects identified the rougher or longer duration stimulus. In both experiments, greater performance accuracy was found on trials where the cue correctly (valid) predicted the changing dimension, vs incorrectly (invalid) cued or no-cue (neutral) trials. More errors on the invalidly vs neutrally cued trials show the cost of focal attention. Increases in performance on validly vs neutrally cued trials show a benefit of filtering irrelevant stimuli in the cued conditions. Results effectively demonstrate focal attention to tactile features. Tests of integrality, in terms of the effects of correlated change in both dimensions, showed no redundancy gain for either vibrotactile or grating tasks, suggesting that frequency and roughness are separable from stimulus duration. Interference of negative correlated change for frequency but not roughness discriminations may be explained by differences in task difficulty.     

Effects of maternal age on oocyte developmental competence

The widespread use of a variety of assisted reproductive technologies has removed many of the constraints that previously restricted mammalian reproduction to the period between onset of puberty and reproductive senescence. In vitro embryo production systems now allow oocytes from very young animals to undergo fertilization and form embryos capable of development to normal offspring, albeit at somewhat reduced efficiencies compared to oocytes from adult females. They also can overcome infertility associated with advanced age of animals and women. This review examines oocyte developmental competence as the limiting factor in applications of assisted reproductive technologies for both juvenile and aged females. Age of oocyte donor is a significant factor influencing developmental competence of the oocyte. Age-related abnormalities of oocytes include a) meiotic incompetence or inability to complete meiotic maturation resulting in oocytes incapable of fertilization; b) errors in meiosis that can be compatible with fertilization but lead to genetic abnormalities that compromise embryo viability; and c) cytoplasmic deficiencies that are expressed at several stages of development before or after fertilization. In general, oocytes from juvenile donors and the embryos derived therefrom appear less robust and may be less tolerant to suboptimal handling and in vitro culture conditions than are adult oocytes. Research to identify specific cytoplasmic deficiencies of juvenile oocytes may enable modifications of culture conditions to correct such deficiencies and thus enhance developmental competence. Use of oocytes from aged donors for assisted reproduction can have a variety of applications such as extending the reproductive life of individual old females whose offspring still have high commercial value, and conservation of genetic resources such as rare breeds of livestock and endangered species. In general, female fertility decreases with advancing age. Studies of women in oocyte donation programs have established reduced oocyte competence as the major cause of declining fertility with age, although inadequate endometrial function can also be a contributing factor. Most research has emphasized the importance of chromosomal abnormalities because of the well established increase in aneuploidy with increasing maternal age but little is known about the underlying cellular and molecular mechanisms. Research aimed at identifying the specific developmental deficiencies of oocytes from juvenile donors and abnormalities of oocytes from aged females will assist in overcoming present bottlenecks that limit the efficiency of assisted reproduction technologies. Such research will also be crucial to the development of new oocyte-based technologies for overcoming infertility and possibly subverting chromosomal abnormalities in women approaching menopause.     

Effects of acute low-level microwaves on pentobarbital-induced hypothermia depend on exposure orientation

Two series of experiments were performed to study the effects of acute exposure (45 min) to 2,450-MHz circularly polarized, pulsed microwaves [1 mW/cm², 2-μs pulses, 500 pps, specific absorption rate (SAR) 0.6 W/kg] on the actions of pentobarbital in the rat. In the first experiment, rats were irradiated with microwaves and then immediately injected with pentobarbital. Microwave exposure did not significantly affect the extent of the pentobarbital-induced fall in colonic temperature. However, the rate of recovery from the hypothermia was significantly slower in the microwave-irradiated rats and they also took a significantly longer time to regain their righting reflex. In a second experiment, rats were first anesthetized with pentobarbital and then exposed to microwaves with their heads either pointing toward the source of microwaves (anterior exposure) or pointing away (posterior exposure). Microwave radiation significantly retarded the pentobarbital-induced fall in colonic temperature regardless of the orientation of exposure. However, the recovery from hypothermia was significantly faster in posterior-exposed animals compared to those of the anterior-exposed and sham-irradiated animals. Furthermore, the posterior-exposed rats took a significantly shorter time to regain their righting reflex than both the anterior-exposed and sham-irradiated animals.     

Effects of nursery table slope orientation on coral survival and growth

Transplanting nursery-reared corals is among one of the most common approaches to assist the recovery of degraded reefs. The nursery phase is considered essential for providing a favourable environment for coral fragments to grow into suitable sizes before transplantation to natural reef substrates. Several types of coral nursery designs have been used, but the effect of nursery table slope orientation on survival and growth of coral fragments has not been fully evaluated. Survival and growth of coral fragments from four species (Pectinia paeonia, Podabacia crustacea, Pocillopora acuta, Merulina ampliata) on three inclinations of nursery table top (horizontal (0°), diagonal (45°) and vertical (90°)) were monitored over six months. The effects of slope orientation on survival and growth of fragments were not significant among species except P. acuta, for which survivorship and growth decreased significantly only on vertical nursery tables. The conditions required for coral propagation, such as slope orientation of nursery tables and the initial size of fragments, clearly differ among species due to their inherent attributes and restoration success will greatly benefit from empirical studies derived from a wider range of species.     

African elephants (Loxodonta africana) recognize visual attention from face and body orientation

How do animals determine when others are able and disposed to receive their communicative signals? In particular, it is futile to make a silent gesture when the intended audience cannot see it. Some non-human primates use the head and body orientation of their audience to infer visual attentiveness when signalling, but whether species relying less on visual information use such cues when producing visual signals is unknown. Here, we test whether African elephants (Loxodonta africana) are sensitive to the visual perspective of a human experimenter. We examined whether the frequency of gestures of head and trunk, produced to request food, was influenced by indications of an experimenter''s visual attention. Elephants signalled significantly more towards the experimenter when her face was oriented towards them, except when her body faced away from them. These results suggest that elephants understand the importance of visual attention for effective communication.     

Effects of age on the acquisition of agreement inflection

Grammaticality judgement tasks show that second language learners who started during childhood are significantly more accurate on judging inflection than learners who started after puberty [Johnson, J., & Newport, E. (1989). Cognitive Psychology, 21, 60–99; Johnson, J., & Newport, E. (1991). Cognition, 39, 215–258; McDonald, J. (2000). Applied Psycholinguistics, 21, 395–423. Production data confirmthat inflection is a bottleneck in adult language acquisition, and that they differ from child learners in this respect [Lardiere, D. (1998). Second Language Research, 14, 359–375; Prévost, P. (2003). Studies in Second Language Acquisition, 25, 65–97; Pre vost, P., & White, L. (2000). Second Language Research, 16(2), 103–133]. Although the observations suggest that the acquisition of inflection is influenced by age, there is no study that focuses on this particular issue nor is there an articulated explanation available for the observed age-related difference. In this contribution, we compare child L2 learners of Dutch to child L1 and adult L2 learners of Dutch in order to investigate effects of age on the acquisition of verbal and adjectival inflection. We hypothesize that adult agreement paradigms differ from child agreement paradigms, the reason being that adult learners cannot rely on syntactic cues, whereas children make reliable use of syntax in building paradigms. By effect, adult learners end up with non-targetlike small paradigms that contain underspecified suffixes. We focus on the types of errors in the three learner groups (child L1, child L2 and adult L2). Our empirical basis consists of results obtained in a series of production experiments. An erratum to this article can be found at