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Behaviour and Growth of Chironomus riparius Meigen (Diptera: Chironomidae) under Imidacloprid Pulse and Constant Exposure Scenarios

Azevedo-Pereira, HMVS; Lemos, MFL; Soares, AMVM
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.12%
Imidacloprid is a new insecticide that mimics nicotine, combining its insecticidal activity with a reduced persistence in the environment. The toxicity of imidacloprid to Chironomus riparius Meigen using the formulated product ConfidorA (R) from BayerA (R), in pulse and continuous exposure, was evaluated in this study. The behavioural response of the midge after toxicant exposure using an online biomonitor was also investigated. Early second-instar C. riparius larvae were exposed in either constant (10 days) or pulse (4 days, followed by 6 days post exposure in clean medium) conditions. Imidacloprid constant exposure resulted in a decrease in growth and impairment of the behavioural pattern of the midge larvae. Pulsed exposure followed by a recovery period revealed a recovery of midge physiological conditions, by reaching a stabilisation of normal behavioural activities and growth among treatments. Moreover, ventilation showed to be a more sensitive parameter by revealing a faster recovery than locomotion. Behaviour alterations may weaken the ability to escape from predators, and reduce food acquisition with consequent growth impairment. These effects may have an impact at the population and community level.

Behavioural response to pain in healthy neonates.

Rushforth, J A; Levene, M I
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1994 Português
Relevância na Pesquisa
46.15%
A bedside technique for evaluating the behavioural response of healthy neonates to pain was assessed. Thirty six term infants (median gestational age 40 weeks; median postnatal age 4 days) and 31 preterm infants (median gestational age 34 weeks; median postnatal age 4 days) were assessed at the cotside for their response to heel preparation and heel lance for routine blood sampling. The facial actions of brow bulge, eye squeeze, nasolabial furrow, and open mouth were noted, and also the presence or absence of crying. Thirty five (97%) term and 26 (84%) preterm infants showed an increase in the number of behaviours in response to heel lance. Brow bulge and nasolabial furrow were seen most often, and occurred more often than crying in the two groups. There was good interobserver agreement (94%). The consistency of response and the high degree of interobserver agreement makes this method of behavioural assessment of acute pain of use in healthy neonates.

Effects of the tachykinin NK1 receptor antagonist, RP 67580, on central cardiovascular and behavioural effects of substance P, neurokinin A and neurokinin B.

Culman, J; Wiegand, B; Spitznagel, H; Klee, S; Unger, T
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1995 Português
Relevância na Pesquisa
36.3%
1. We have investigated the effects of the non-peptide NK1 tachykinin receptor antagonist, RP 67580, and its inactive enantiomer, RP 68651, on the cardiovascular and behavioural responses to substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) injected intracerebroventricularly (i.c.v.) in conscious rats. 2. The SP and NKA (25 pmol)-induced increases in blood pressure (BP) and heart rate (HR) were of the same magnitude. The cardiovascular responses to both peptides were associated with excessive grooming behaviour and wet dog shakes (WDS). Relative to SP, NKA was weaker in inducing hindquarter grooming (HG), but more effective in eliciting WDS. The cardiovascular response to NKB (50 pmol) comprised an increase in BP and HR, while the behavioural response was weak. 3. RP 67580 (100 pmol), injected 10 or 30 min prior to SP, effectively inhibited the cardiovascular and behavioural responses to the peptide whereas lower doses were ineffective. Pretreatment with 500 pmol of RP 67580, 10 or 30 min prior to SP, reduced the BP response. Of the behavioural manifestations, only face washing was attenuated when the antagonist was injected 10 min before SP. At 2500 pmol, the antagonist exaggerated the BP response to the peptide without affecting the behavioural response. RP 68651 (100 or 2500 pmol) did not modify the central responses to SP. 4. Neither RP 67580 nor RP 68651 (100 pmol)...

Repeated chlorpromazine administration increases a behavioural response of rats to 5-hydroxytryptamine receptor stimulation.

Green, A R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1977 Português
Relevância na Pesquisa
46.01%
1 The hyperactivity syndrome produced in rats by administration of tranylcypromine (20 mg/kg i.p.) followed 30 min later by L-tryptophan (50 mg/kg i.p.) is generally considered to be due to increased 5-hydroxytryptamine (5-HT) functional activity. It is inhibited by chlorpromazine (30 mg/kg i.p.) injected 60 min before the tranylcypromine. However, chlorpromazine injection for 4 days either at a dose of 30 mg/kg once daily or 5 mg/kg twice daily results in an enhanced hyperactivity response to tranylcypromine and L-tryptophan administration 24 h after the final dose of chlorpromazine. 2 One injection of chlorpromazine (30 mg/kg) did not produce enhancement 24 h later and the inhibition of the tranylcypromine/L-tryptophan hyperactivity observed after acute chlorpromazine injection was seen if the rats were given tranylcypromine and L-tryptophan 1 h after the fourth chlorpromazine (30 mg/kg) dose. 3 Chlorpromazine (30 mg/kg) once daily or 5 mg/kg twice daily for 4 days resulted in rats displaying enhanced behavioral responses to the suggested 5-HT agonist 5-methoxy N,N-dimethyltryptamine (2 mg/kg) on day 5. 4 Chlorpromazine (30 mg/kg) once daily for 4 days produces a slight increase in brain 5-hydroxytryptamine (5-HT) concentration on day 5...

Signals and behavioural responses are not coupled in males: aggression affected by replacement of an evolutionarily lost colour signal.

Quinn, V S; Hews, D K
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 22/04/2000 Português
Relevância na Pesquisa
36.16%
Male Sceloporus virgatus lack the blue abdominal patches which are used during aggressive encounters in other Sceloporus lizards. Herein we report that, despite having lost this signal, males have retained a behavioural response to experimentally restored blue abdominal patches. We tested two adaptive hypotheses: selection acted primarily upon signallers or selection acted upon both signallers and receivers. The first predicts that only the signal is lost and that male interactions should be affected by the restoration of blue patches. The latter predicts that both the signal and behavioural response are lost and the display of the restored blue patches should have no effect on male-male interactions. We compared the behaviour of receivers in paired encounters where one male (signaller) had blue-painted abdominal patches to a set of trials where both males had white-painted abdomens, unmanipulated abdomens or a novel-painted pattern. The receivers of the blue-painted signal were more likely to display submissive behaviour. The receivers in either the unmanipulated, white-painted or novel-painted signal trials were more likely to display neutral behaviour. These results support the hypothesis that receivers have retained a behavioural response and selection has acted primarily on the signaller. We believe this is the first documentation of males responding to an evolutionarily lost signal in conspecific males.

Changes in the behavioural response to a TRH analogue following chronic amitriptyline treatment and repeated electroconvulsive shock in the rat.

Bennett, G. W.; Green, A. R.; Lighton, C.; Marsden, C. A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1986 Português
Relevância na Pesquisa
46.01%
The arousal elicited in rats by injection into the nucleus accumbens of the thyrotrophin-releasing hormone analogue CG 3509 (orotyl-histidyl-prolineamide) was used to assess the responsiveness to thyrotrophin-releasing hormone following repeated treatment with amitriptyline or electroconvulsive shock. Fourteen day administration of amitriptyline (15 mg kg-1 i.p. twice daily) reduced the behavioural response to bilateral intra-accumbens injection of CG 3509 (2 X 2.5 micrograms). CG 3509-induced hyperactivity, recovery from pentobarbitone-induced anaesthesia and the reversal of both pentobarbitone-induced hypothermia and decreased respiration, were all significantly reduced compared to either the response of the animals prior to amitriptyline administration or that observed in rats following chronic saline administration. Repeated administration of electroconvulsive shock (5 shocks over 10 days) significantly increased CG 3509-induced hyperactivity and the degree of reversal of pentobarbitone-induced hypothermia and respiratory depression following CG 3509 administration. The results demonstrate that chronic antidepressant treatments alter the central functional responsiveness to thyrotrophin-releasing hormone. These changes are discussed with respect to the effects of antidepressant treatments on 5-hydroxytryptamine receptors and possible thyrotrophin-releasing hormone--aminergic interactions.

The effects of substance P analogues on the scratching, biting and licking response induced by intrathecal injection of N-methyl-D-aspartate in mice.

Sakurada, T.; Manome, Y.; Tan-No, K.; Sakurada, S.; Kisara, K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1990 Português
Relevância na Pesquisa
36.16%
1. Intrathecal (i.t.) administration of N-methyl-D-aspartate (NMDA) elicited a dose-dependent behavioural response consisting of licking, biting and scratching in mice. 2. Repeated i.t. injections of 0.4 nmol NMDA, at 5 min intervals, resulted in the rapid development of desensitization to this NMDA-induced behavioural phenomenon. 3. The NMDA-induced response was dose-dependently inhibited by the simultaneous injection of a selective NMDA-receptor antagonist, D-2-amino-5-phosphonovaleric acid. 4. The substance P (SP) analogues [D-Pro2, D-Trp7,9] SP and [D-Arg1, D-Trp7,9, Leu11] SP (spantide) inhibited NMDA-induced behavioural responses in a dose-dependent manner. However, [D-Phe7, D-His9] SP (6-11), a SP analogue selective for neurokinin1 (NK1) receptors, failed to inhibit NMDA-induced responses even at a dose of 4.0 nmol. 5. These results indicate that NMDA-induced behavioural responses are mainly mediated through NMDA receptors without affecting NK1 receptors in the spinal cord.

A behavioural and ERP investigation of 3-month-olds’ face preferences

Cassia, Viola Macchi; Kuefner, Dana; Westerlund, Alissa; Nelson, Charles A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.16%
Recent behavioural work suggests that newborn face preferences are derived from a general, non-specific attentional bias toward patterns with more features in the upper versus lower half. In the current study we predicted that selectivity for the specific geometry of the face may emerge during the first 3 months of life as a product of perceptual narrowing, leading to the construction of the first broadly defined face category segregating faces from other visual objects which may share with faces one or more visual properties. This was investigated behaviourally, using a standard preferential looking paradigm, and electrophysiologically, using high-density ERPs. Behavioural results indicated that, at 3 months, the top-heavy property is no longer a crucial factor in determining face preferences. ERP results showed evidence of differentiation between the two stimuli only for the N700. No differentiation was found for earlier components that are thought to reflect the adult-like structural encoding stage of face processing in infants (N290 and P400). Together, ERP and behavioural results suggest that, by 3 months, the perceptual narrowing process has led to a behavioural response specific to the geometry of the human face, but that this response is not purely perceptual in nature. Rather...

Male response to historical and geographical variation in bird song

Derryberry, Elizabeth P.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.15%
In many species, individuals discriminate among sexual signals of conspecific populations in the contexts of mate choice and male–male competition. Differences in signals among populations (geographical variation) are in part the result of signal evolution within populations (temporal variation). Understanding the relative effect of temporal and geographical signal variation on signal salience may therefore provide insight into the evolution of behavioural discrimination. However, no study, to my knowledge, has compared behavioural response to historical signals with response to current signal variation among populations. Here, I measured the response of male white-crowned sparrows (Zonotrichia leucophrys) to historical songs compared with current songs from their local population, a nearby non-local population and a distant population. Males responded most strongly to current local songs, less, but equally, to historical local and current non-local songs, and least to songs of the distant population. Moreover, response to both temporal and geographical variation in song was proportional to how much songs differed acoustically from current local songs. Signal evolution on an ecological time scale appears to have an effect on signal salience comparable to differences found between current neighbouring populations...

Behavioural Response Thresholds in New Zealand Crab Megalopae to Ambient Underwater Sound

Stanley, Jenni A.; Radford, Craig A.; Jeffs, Andrew G.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/12/2011 Português
Relevância na Pesquisa
46.22%
A small number of studies have demonstrated that settlement stage decapod crustaceans are able to detect and exhibit swimming, settlement and metamorphosis responses to ambient underwater sound emanating from coastal reefs. However, the intensity of the acoustic cue required to initiate the settlement and metamorphosis response, and therefore the potential range over which this acoustic cue may operate, is not known. The current study determined the behavioural response thresholds of four species of New Zealand brachyuran crab megalopae by exposing them to different intensity levels of broadcast reef sound recorded from their preferred settlement habitat and from an unfavourable settlement habitat. Megalopae of the rocky-reef crab, Leptograpsus variegatus, exhibited the lowest behavioural response threshold (highest sensitivity), with a significant reduction in time to metamorphosis (TTM) when exposed to underwater reef sound with an intensity of 90 dB re 1 µPa and greater (100, 126 and 135 dB re 1 µPa). Megalopae of the mud crab, Austrohelice crassa, which settle in soft sediment habitats, exhibited no response to any of the underwater reef sound levels. All reef associated species exposed to sound levels from an unfavourable settlement habitat showed no significant change in TTM...

Spatial and Temporal Attention Modulate the Early Stages of Face Processing: Behavioural Evidence from a Reaching Paradigm

Quek, Genevieve L.; Finkbeiner, Matthew
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 28/02/2013 Português
Relevância na Pesquisa
36.2%
A presently unresolved question within the face perception literature is whether attending to the location of a face modulates face processing (i.e. spatial attention). Opinions on this matter diverge along methodological lines – where neuroimaging studies have observed that the allocation of spatial attention serves to enhance the neural response to a face, findings from behavioural paradigms suggest face processing is carried out independently of spatial attention. In the present study, we reconcile this divide by using a continuous behavioural response measure that indexes face processing at a temporal resolution not available in discrete behavioural measures (e.g. button press). Using reaching trajectories as our response measure, we observed that although participants were able to process faces both when attended and unattended (as others have found), face processing was not impervious to attentional modulation. Attending to the face conferred clear benefits on sex-classification processes at less than 350ms of stimulus processing time. These findings constitute the first reliable demonstration of the modulatory effects of both spatial and temporal attention on face processing within a behavioural paradigm.

Multivariate analysis of behavioural response experiments in humpback whales (Megaptera novaeangliae)

Dunlop, Rebecca A.; Noad, Michael J.; Cato, Douglas H.; Kniest, Eric; Miller, Patrick J. O.; Smith, Joshua N.; Stokes, M. Dale
Fonte: Company of Biologists Publicador: Company of Biologists
Tipo: Artigo de Revista Científica
Publicado em 01/03/2013 Português
Relevância na Pesquisa
46.22%
The behavioural response study (BRS) is an experimental design used by field biologists to determine the function and/or behavioural effects of conspecific, heterospecific or anthropogenic stimuli. When carrying out these studies in marine mammals it is difficult to make basic observations and achieve sufficient samples sizes because of the high cost and logistical difficulties. Rarely are other factors such as social context or the physical environment considered in the analysis because of these difficulties. This paper presents results of a BRS carried out in humpback whales to test the response of groups to one recording of conspecific social sounds and an artificially generated tone stimulus. Experiments were carried out in September/October 2004 and 2008 during the humpback whale southward migration along the east coast of Australia. In total, 13 ‘tone’ experiments, 15 ‘social sound’ experiments (using one recording of social sounds) and three silent controls were carried out over two field seasons. The results (using a mixed model statistical analysis) suggested that humpback whales responded differently to the two stimuli, measured by changes in course travelled and dive behaviour. Although the response to ‘tones’ was consistent...

Brain size affects the behavioural response to predators in female guppies (Poecilia reticulata)

van der Bijl, Wouter; Thyselius, Malin; Kotrschal, Alexander; Kolm, Niclas
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 07/08/2015 Português
Relevância na Pesquisa
46.01%
Large brains are thought to result from selection for cognitive benefits, but how enhanced cognition leads to increased fitness remains poorly understood. One explanation is that increased cognitive ability results in improved monitoring and assessment of predator threats. Here, we use male and female guppies (Poecilia reticulata), artificially selected for large and small brain size, to provide an experimental evaluation of this hypothesis. We examined their behavioural response as singletons, pairs or shoals of four towards a model predator. Large-brained females, but not males, spent less time performing predator inspections, an inherently risky behaviour. Video analysis revealed that large-brained females were further away from the model predator when in pairs but that they habituated quickly towards the model when in shoals of four. Males stayed further away from the predator model than females but again we found no brain size effect in males. We conclude that differences in brain size affect the female predator response. Large-brained females might be able to assess risk better or need less sensory information to reach an accurate conclusion. Our results provide experimental support for the general idea that predation pressure is likely to be important for the evolution of brain size in prey species.

Resisting behavioural change: proposal-resistance sequences in cognitive behavioural therapy sessions for clients with depression.

Simmons, Katherine Anne
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010 Português
Relevância na Pesquisa
36.18%
The thesis examines some of the standard ways in which therapists attempt to initiate behavioural change in clients attending Cognitive Behavioural Therapy (CBT) sessions for the treatment of depression, and highlights the interactional consequences that follow from such attempts. CBT is one of the most widely used treatments for depression across the Western world. Previous research on the use of CBT for depression has largely involved outcome studies that measure the overall effectiveness of this form of treatment. These studies have not examined the specific aspects of CBT practice that allow therapists and clients to accomplish particular therapeutic goals. The analysis undertaken in this thesis was concerned with identifying the different ways by which therapists accomplished one specific CBT practice – that of behavioural activation. Conversation analysis (CA) was used to analyse a corpus of 20 naturally-occurring CBT sessions involving clients diagnosed with depression. The sessions were recorded at the Centre for the Treatment of Depression and Anxiety (CTAD) in Adelaide, a university-affiliated teaching clinic that specializes in CBT treatment. Sessions were one-on-one with the therapist and client, and typically lasted one hour. The analysis showed that when therapists approached the practice of behavioural activation by proposing their own suggestions for behavioural change - in what might be referred to as a non-collaborative manner - widespread client resistance ensued. That is...

Behavioural responses of Risso’s dolphin, Grampus griseus, to remote biopsy sampling

Hartman, Karin L.; Wittich, Anja; Neves, Dalia; Azevedo, José M. N.
Fonte: Universidade dos Açores Publicador: Universidade dos Açores
Tipo: Conferência ou Objeto de Conferência
Publicado em /03/2011 Português
Relevância na Pesquisa
36.22%
25th Conference of the European Cetacean Society. Long-terms datasets on marine mammals: learning from the past to manage the future, Cadiz, Spain, 21-23 March 2011.; Biopsy sampling from free-ranging cetaceans is a widespread method used in various biological studies. Since this is an intrusive research technique, it’s important to determine its impact. We examined the short-term behavioural reactions of Risso’s dolphins, Grampus griseus (2.6-4m in length), off Pico Island, to remote biopsy sampling. Biopsies were conducted over a consecutive two year period using a crossbow with Finn Larsen bolts and tips. Sampling followed a number of precautionary rules, including taking samples only in calm seas, when animals were travelling; no more than 1-4 shots per group; and females with nursing calves were not exposed to sampling. Behavioural responses were analysed by visual observation using two scales of behavioural reactions: i) the reaction of the targeted individual, and ii) the reaction of the focal group to which the targeted individual belonged. We defined five categories of intensity of behavioural response (none, low, medium, high, very high) and five types of display response (quick dive, QD; diving & leaving, D&L; jumping...

Can topical lignocaine reduce behavioural response to heel prick?

Rushforth, J. A.; Griffiths, G.; Thorpe, H.; Levene, M. I.
Fonte: BMJ Group Publicador: BMJ Group
Tipo: Artigo de Revista Científica
Publicado em /01/1995 Português
Relevância na Pesquisa
46.1%
In a randomised, double blind, controlled study the ability of 5% lignocaine ointment to reduce the behavioural response to heel lance in 30 healthy neonates was assessed. Five per cent lignocaine ointment applied to the heel under an occlusive dressing for one hour before heel prick did not reduce the infants' behavioural response to the heel prick procedure.

Predicting behavioural response to TDCS in chronic motor stroke☆

O'Shea, Jacinta; Boudrias, Marie-Hélène; Stagg, Charlotte Jane; Bachtiar, Velicia; Kischka, Udo; Blicher, Jakob Udby; Johansen-Berg, Heidi
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Publicado em 15/01/2014 Português
Relevância na Pesquisa
46.26%
Transcranial direct current stimulation (TDCS) of primary motor cortex (M1) can transiently improve paretic hand function in chronic stroke. However, responses are variable so there is incentive to try to improve efficacy and or to predict response in individual patients. Both excitatory (Anodal) stimulation of ipsilesional M1 and inhibitory (Cathodal) stimulation of contralesional M1 can speed simple reaction time. Here we tested whether combining these two effects simultaneously, by using a bilateral M1–M1 electrode montage, would improve efficacy. We tested the physiological efficacy of Bilateral, Anodal or Cathodal TDCS in changing motor evoked potentials (MEPs) in the healthy brain and their behavioural efficacy in changing reaction times with the paretic hand in chronic stroke. In addition, we aimed to identify clinical or neurochemical predictors of patients' behavioural response to TDCS. There were three main findings: 1) unlike Anodal and Cathodal TDCS, Bilateral M1–M1 TDCS (1 mA, 20 min) had no significant effect on MEPs in the healthy brain or on reaction time with the paretic hand in chronic stroke patients; 2) GABA levels in ipsilesional M1 predicted patients' behavioural gains from Anodal TDCS; and 3) although patients were in the chronic phase...

Taking a Comparative Approach: Analysing Personality as a Multivariate Behavioural Response across Species

Carter, Alecia J.; Feeney, William E.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 31/07/2012 Português
Relevância na Pesquisa
36.2%
Animal personality, repeatable behaviour through time and across contexts, is ecologically and evolutionarily important as it can account for the exhibition of sub-optimal behaviours. Interspecific comparisons have been suggested as important for understanding the evolution of animal personality; however, these are seldom accomplished due, in part, to the lack of statistical tools for quantifying differences and similarities in behaviour between groups of individuals. We used nine species of closely-related coral reef fishes to investigate the usefulness of ecological community analyses for the analysis of between-species behavioural differences and behavioural heterogeneity. We first documented behavioural carryover across species by observing the fishes' behaviour and measuring their response to a threatening stimulus to quantify boldness. Bold fish spent more time away from the reef and fed more than shy fish. We then used ecological community analysis tools (canonical variate analysis, multi-response permutation procedure, and permutational analysis of multivariate dispersion) and identified four ‘clusters’ of behaviourally similar fishes, and found that the species differ in the behavioural variation expressed; some species are more behaviourally heterogeneous than others. We found that ecological community analysis tools are easily and fruitfully applied to comparative studies of personality and encourage their use by future studies.

The Behavioural Response of Australian Fur Seals to Motor Boat Noise

Tripovich, Joy S.; Hall-Aspland, Sophie; Charrier, Isabelle; Arnould, John P. Y.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 18/05/2012 Português
Relevância na Pesquisa
46.06%
Australian fur seals breed on thirteen islands located in the Bass Strait, Australia. Land access to these islands is restricted, minimising human presence but boat access is still permissible with limitations on approach distances. Thirty-two controlled noise exposure experiments were conducted on breeding Australian fur seals to determine their behavioural response to controlled in-air motor boat noise on Kanowna Island (39°10′S, 146°18′E). Our results show there were significant differences in the seals' behaviour at low (64–70 dB) versus high (75–85 dB) sound levels, with seals orientating themselves towards or physically moving away from the louder boat noise at three different sound levels. Furthermore, seals responded more aggressively with one another and were more alert when they heard louder boat noise. Australian fur seals demonstrated plasticity in their vocal responses to boat noise with calls being significantly different between the various sound intensities and barks tending to get faster as the boat noise got louder. These results suggest that Australian fur seals on Kanowna Island show behavioural disturbance to high level boat noise. Consequently, it is recommended that an appropriate level of received boat sound emissions at breeding fur seal colonies be below 74 dB and that these findings be taken into account when evaluating appropriate approach distances and speed limits for boats.

Mechanisms of human motion perception: combining evidence from evoked potentials, behavioural performance, and computational modelling.

Patzwahl, D; Zanker, Johannes
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.1%
Based on single cell recordings in monkey, it has been suggested that neural activity can be related directly to psychophysically measured threshold behaviour. Here, we investigated in humans whether evoked potentials correlate with behavioural measurements like discrimination thresholds and reaction time. Subjects were asked to report the perceived direction of object motion stimuli which contained variable amounts of coherent motion. Simultaneously, we recorded evoked potentials with a multielectrode array, or measured the reaction time. We show here that motion coherence had a strong influence on both amplitude and latency of the evoked potential. Stronger motion signals evoked stronger and faster cortical responses. The latency reduction of the motion onset response with increasing coherence correlated very well with the concurrent decrease in reaction time. Taken together, these results suggest that temporal integration is an important step in analysing motion signals to generate a reliable behavioural response. We stimulated a two-dimensional array of correlation-type motion detectors with the same motion sequences, and analysed the distribution of local motion signals according to signal detection theory. Performance resembled that of human subjects when the decision strategy was optimized so as to exclude small signals and...