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1.
Nat Commun ; 12(1): 771, 2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33536422

RESUMO

Many animals use the Earth's geomagnetic field for orientation and navigation. Yet, the molecular and cellular underpinnings of the magnetic sense remain largely unknown. A biophysical model proposed that magnetoreception can be achieved through quantum effects of magnetically-sensitive radical pairs formed by the photoexcitation of cryptochrome (CRY) proteins. Studies in Drosophila are the only ones to date to have provided compelling evidence for the ultraviolet (UV)-A/blue light-sensitive type 1 CRY (CRY1) involvement in animal magnetoreception, and surprisingly extended this discovery to the light-insensitive mammalian-like type 2 CRYs (CRY2s) of both monarchs and humans. Here, we show that monarchs respond to a reversal of the inclination of the Earth's magnetic field in an UV-A/blue light and CRY1, but not CRY2, dependent manner. We further demonstrate that both antennae and eyes, which express CRY1, are magnetosensory organs. Our work argues that only light-sensitive CRYs function in animal light-dependent inclination-based magnetic sensing.


Assuntos
Borboletas/fisiologia , Criptocromos/metabolismo , Proteínas de Insetos/metabolismo , Campos Magnéticos , Orientação/fisiologia , Sensação/fisiologia , Sequência de Aminoácidos , Animais , Antenas de Artrópodes/fisiologia , Antenas de Artrópodes/efeitos da radiação , Borboletas/genética , Borboletas/efeitos da radiação , Criptocromos/genética , Olho/efeitos da radiação , Humanos , Proteínas de Insetos/genética , Luz , Mutação , Orientação/efeitos da radiação , Sensação/genética , Sensação/efeitos da radiação , Homologia de Sequência de Aminoácidos
2.
Sportis (A Coruña) ; 6(3): 517-532, sept. 2020. ilus, graf, tab
Artigo em Inglês | IBECS | ID: ibc-197062

RESUMO

The purpose of this study is to determine the effect of an acute local vibration exercise on the visual reaction time of a fencer's upper body extremities. Twenty-six male fencers between the ages of 15 and 23 (mean age, 17.38 ± 2.13 years, height: 173.6±9.1 cm, body mass: 70.2 ±14.1 kg) volunteered for this study. The reaction time test was applied before and after the vibration exercise (applied for 30 seconds in 27 Hz with a 2-mm amplitude). After 25 min. standard warming up, fencers were informed about the test, and three repeated reaction tests were performed to provide familiarization. The fencers started the reaction test in the standard fencing guard position. According to five signals coming at two to five second intervals from the target monitor, the fencers made touché by bending (attacking). The reaction time test had five trials. The average reaction time values pre-vibration, and post-vibration were compared. The visual reaction time measured pre-vibration were significantly longer than those measured post-vibration (p < 0.001). Acute local vibration exercise applied to fencers shortened the visual reaction time. Given the fact that vibration can improve RT, the use of vibration in training has the potential to provide an advantage to fencers


El propósito de este estudio es determinar el efecto de un ejercicio de vibración local aguda en el tiempo de reacción visual de las extremidades superiores de un esgrimidor. Veintiséis esgrimidores masculinos entre las edades de 15 y 23 (edad media, 17.38 ± 2.13 años, altura: 173.6 ± 9.1 cm, masa corporal: 70.2 ± 14.1 kg) se ofrecieron como voluntarios para este estudio. La prueba del tiempo de reacción se aplicó antes y después del ejercicio de vibración (aplicado durante 30 segundos en 27 Hz con una amplitud de 2 mm). Después de 25 min. calentamiento estándar, se informó a los esgrimidores sobre la prueba y se realizaron tres pruebas de reacción repetidas para proporcionar familiarización. Los esgrimidores comenzaron la prueba de reacción en la posición estándar de protección de esgrima. De acuerdo con cinco señales que vienen a intervalos de dos a cinco segundos desde el monitor objetivo, los esgrimistas hicieron un toque al doblarse (atacar). La prueba del tiempo de reacción tuvo cinco ensayos. Se compararon los valores promedio de tiempo de reacción pre-vibración y post-vibración. El tiempo de reacción visual medido antes de la vibración fue significativamente mayor que el medido después de la vibración (p <0.001). El ejercicio de vibración local aguda aplicado a los esgrimidores acortó el tiempo de reacción visual. Dado que la vibración puede mejorar la RT, el uso de la vibración en el entrenamiento tiene el potencial de proporcionar una ventaja a los esgrimidores


Assuntos
Humanos , Masculino , Adolescente , Adulto Jovem , Adulto , Vibração , Visão Ocular/fisiologia , Esportes/fisiologia , Tempo de Reação/fisiologia , Desempenho Atlético/fisiologia , Desempenho Psicomotor/fisiologia , Percepção Espacial/fisiologia , Reflexo/fisiologia , Movimentos Oculares/fisiologia , Orientação/fisiologia , Software , Antropometria
3.
An Acad Bras Cienc ; 92(2): e20190564, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32556052

RESUMO

We studied the multiunit responses to moving and static stimuli from 585 cell clusters in area MT using multi-electrode arrays. Our aim was to explore if MT columns exhibit any larger-scale tangential organization or clustering based on their response properties. Neurons showing both motion and orientation selectivity were classified into four categories: 1- Type I (orientation selectivity orthogonal to the axis of motion); 2- Type II (orientation selectivity coaxial to the axis of motion); 3- Type DS (significant response to moving stimuli, but non-significant response to static stimuli); and 4- Type OS (significant orientation selectivity, but non-significant direction selectivity). Type I (34%), Type II (24%) and Type DS (32%) clusters were the most predominant and may be associated with different stages of motion processing in MT. On the other hand, the rarer Type OS (9%) may be integrating motion and form processing. Type I and unidirectional sites were the only classes to exhibit significant clustering. Type OS sites showed a trend for clustering, which did not reach statistical significance. We also found a trend for unidirectional sites to have bidirectional sites as neighbors. In conclusion, neuronal clustering associated with these four categories may be related to distinct MT functional circuits.


Assuntos
Neurônios/fisiologia , Orientação/fisiologia , Sapajus apella/fisiologia , Lobo Temporal/fisiologia , Vias Visuais/fisiologia , Percepção Visual/fisiologia , Animais
4.
J Vis ; 20(6): 7, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32525986

RESUMO

Perceptual learning and contextual learning are two types of implicit visual learning that can co-occur in the same tasks. For example, to find an animal in the woods, you need to know where to look in the environment (contextual learning) and you must be able to discriminate its features (perceptual learning). However, contextual and perceptual learning are typically studied using distinct experimental paradigms, and little is known regarding their comparative neural mechanisms. In this study, we investigated contextual and perceptual learning in 12 healthy adult humans as they performed the same visual search task, and we examined psychophysical and electrophysiological (event-related potentials) measures of learning. Participants were trained to look for a visual stimulus, a small line with a specific orientation, presented among distractors. We found better performance for the trained target orientation as compared to an untrained control orientation, reflecting specificity of perceptual learning for the orientation of trained elements. This orientation specificity effect was associated with changes in the C1 component. We also found better performance for repeated spatial configurations as compared to novel ones, reflecting contextual learning. This context-specific effect was associated with the N2pc component. Taken together, these results suggest that contextual and perceptual learning are distinct visual learning phenomena that have different behavioral and electrophysiological characteristics.


Assuntos
Potenciais Evocados/fisiologia , Aprendizagem Espacial/fisiologia , Percepção Visual/fisiologia , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Orientação/fisiologia , Orientação Espacial , Psicofísica , Adulto Jovem
5.
PLoS Comput Biol ; 16(5): e1007489, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32379824

RESUMO

Path integration is thought to rely on vestibular and proprioceptive cues yet most studies in humans involve primarily visual input, providing limited insight into their respective contributions. We developed a paradigm involving walking in an omnidirectional treadmill in which participants were guided on two sides of a triangle and then found their back way to origin. In Experiment 1, we tested a range of different triangle types while keeping the distance of the unguided side constant to determine the influence of spatial geometry. Participants overshot the angle they needed to turn and undershot the distance they needed to walk, with no consistent effect of triangle type. In Experiment 2, we manipulated distance while keeping angle constant to determine how path integration operated over both shorter and longer distances. Participants underestimated the distance they needed to walk to the origin, with error increasing as a function of the walked distance. To attempt to account for our findings, we developed configural-based computational models involving vector addition, the second of which included terms for the influence of past trials on the current one. We compared against a previously developed configural model of human path integration, the Encoding-Error model. We found that the vector addition models captured the tendency of participants to under-encode guided sides of the triangles and an influence of past trials on current trials. Together, our findings expand our understanding of body-based contributions to human path integration, further suggesting the value of vector addition models in understanding these important components of human navigation.


Assuntos
Orientação/fisiologia , Percepção Espacial/fisiologia , Navegação Espacial/fisiologia , Adulto , Biologia Computacional/métodos , Sinais (Psicologia) , Feminino , Humanos , Masculino , Modelos Teóricos , Propriocepção/fisiologia , Caminhada/fisiologia
6.
J Neurosci ; 40(28): 5455-5464, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32471878

RESUMO

Previous studies have indicated that both increased physical salience and increased reward-value salience of a target improve behavioral measures of attentional selection. It is unclear, however, whether these two forms of salience interact with attentional networks through similar or different neural mechanisms, and what such differences might be. We examined this question by separately manipulating both the value-driven and physical salience of targets in a visual search task while recording response times (RTs) and event-related potentials, focusing on the attentional-orienting-sensitive N2pc event-related potential component. Human participants of both sexes searched arrays for targets of either a high-physical-salience color or one of two low-physical-salience colors across three experimental phases. The first phase ("baseline") offered no rewards. RT and N2pc latencies were shorter for high-physical-salience targets, indicating faster attentional orienting. In the second phase ("equal-reward"), a low monetary reward was given for fast correct responses for all target types. This reward context improved overall performance, similarly shortening RTs and enhancing N2pc amplitudes for all target types, but with no change in N2pc latencies. In the third phase ("selective-reward"), the reward rate was made selectively higher for one of the two low-physical-salience colors, resulting in their RTs becoming as fast as the high-physical-salience targets. Despite the equally fast RTs, the N2pc's for these low-physical-salience, high-value targets remained later than for high-physical-salience targets, instead eliciting significantly larger N2pc's. These results suggest that enhanced physical salience leads to faster attentional orienting, but value-driven salience to stronger attentional orienting, underscoring the utilization of different underlying mechanisms.SIGNIFICANCE STATEMENT Associating relevant target stimuli with reward value can enhance their salience, facilitating their attentional selection. This value-driven salience improves behavioral performance, similar to the effects of physical salience. Recent theories, however, suggest that these forms of salience are intrinsically different, although the neural mechanisms underlying any such differences remain unclear. This study addressed this issue by manipulating the physical and value-related salience of targets in a visual search task, comparing their effects on several attention-sensitive neural-activity measures. Our findings show that, whereas physical salience accelerates the speed of attentional selection, value-driven salience selectively enhances its strength. These findings shed new insights into the theoretical and neural underpinnings of value-driven salience and its effects on attention and behavior.


Assuntos
Atenção/fisiologia , Potenciais Evocados/fisiologia , Orientação/fisiologia , Recompensa , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Tempo de Reação/fisiologia , Percepção Visual/fisiologia , Adulto Jovem
7.
Sci Rep ; 10(1): 7698, 2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32382101

RESUMO

Common cuckoos Cuculus canorus are obligate nest parasites yet young birds reach their distant, species-specific wintering grounds without being able to rely on guidance from experienced conspecifics - in fact they never meet their parents. Naïve marine animals use an inherited navigational map during migration but in inexperienced terrestrial animal migrants unequivocal evidence of navigation is lacking. We present satellite tracking data on common cuckoos experimentally displaced 1,800 km eastward from Rybachy to Kazan. After displacement, both young and adult travelled similarly towards the route of non-displaced control birds. The tracking data demonstrate the potential for young common cuckoos to return to the species-specific migration route after displacement, a response so far reported exclusively in experienced birds. Our results indicate that an inherited map allows first-time migrating cuckoos to locate suitable wintering grounds. This is in contrast to previous studies of solitary terrestrial bird migrants but similar to that reported from the marine environment.


Assuntos
Migração Animal/fisiologia , Aves/fisiologia , Asas de Animais/fisiologia , Animais , Orientação/fisiologia , Estações do Ano
8.
Sci Rep ; 10(1): 7267, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32350332

RESUMO

Inhibition of return (IOR) is the reduction of detection speed and/or detection accuracy of a target in a recently attended location. This phenomenon, which has been discovered and studied thoroughly in humans, is believed to reflect a brain mechanism for controlling the allocation of spatial attention in a manner that enhances efficient search. Findings showing that IOR is robust, apparent at a very early age and seemingly dependent on midbrain activity suggest that IOR is a universal attentional mechanism in vertebrates. However, studies in non-mammalian species are scarce. To explore this hypothesis comparatively, we tested for IOR in barn owls (Tyto alba) using the classical Posner cueing paradigm. Two barn owls were trained to initiate a trial by fixating on the center of a computer screen and then turning their gaze to the location of a target. A short, non-informative cue appeared before the target, either at a location predicting the target (valid) or a location not predicting the target (invalid). In one barn owl, the response times (RT) to the valid targets compared to the invalid targets shifted from facilitation (lower RTs) to inhibition (higher RTs) when increasing the time lag between the cue and the target. The second owl mostly failed to maintain fixation and responded to the cue before the target onset. However, when including in the analysis only the trials in which the owl maintained fixation, an inhibition in the valid trials could be detected. To search for the neural correlates of IOR, we recorded multiunit responses in the optic tectum (OT) of four head-fixed owls passively viewing a cueing paradigm as in the behavioral experiments. At short cue to target lags (<100 ms), neural responses to the target in the receptive field (RF) were usually enhanced if the cue appeared earlier inside the RF (valid) and were suppressed if the cue appeared earlier outside the RF (invalid). This was reversed at longer lags: neural responses were suppressed in the valid conditions and were unaffected in the invalid conditions. The findings support the notion that IOR is a basic mechanism in the evolution of vertebrate behavior and suggest that the effect appears as a result of the interaction between lateral and forward inhibition in the tectal circuitry.


Assuntos
Atenção/fisiologia , Encéfalo/fisiologia , Fluxo Óptico/fisiologia , Orientação/fisiologia , Tempo de Reação/fisiologia , Estrigiformes/fisiologia , Animais
9.
Invest Ophthalmol Vis Sci ; 61(5): 5, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32392311

RESUMO

Purpose: We investigated and characterized the patterns of meridional anisotropies in newly diagnosed refractive amblyopes using pattern onset-offset visual evoked potentials (POVEPs) and psychophysical grating acuity (GA). Methods: Twenty-five refractive amblyopes were recruited and compared with non-amblyopic controls from our previous study. Monocular POVEPs were recorded in response to sinewave 4 cycles per degree (cpd) grating stimuli oriented along each individual participants' principal astigmatic meridians, which were approximately horizontal (meridian 1) and vertical (meridian 2). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed along the same meridians using a two-alternative non-forced-choice technique. The C3 amplitudes and peak latencies of the POVEPs and GAs were compared across meridians for both groups (refractive amblyopes and controls) using linear mixed models (monocular) and ANOVA (binocular), and post hoc analysis was conducted to determine if meridional anisotropies in this cohort of amblyopes were related to low (≤1.50 diopters [D]), moderate (1.75-2.75 D) and high (≥3.00 D) astigmatism. Results: In the newly diagnosed refractive amblyopes, there were no significant meridional anisotropies across all outcome measures, but the post hoc analysis demonstrated that C3 amplitude was significantly higher in those with low (P = 0.02) and moderate (P = 0.004) astigmatism compared to those with high astigmatism. Refractive amblyopes had poorer GA and C3 amplitudes compared to controls by approximately two lines on the logMAR chart (monocular: P = 0.013; binocular: P = 0.014) and approximately 6 µV (monocular: P = 0.009; binocular: P = 0.027), respectively. Conclusions: Deleterious effects of high astigmatism was evident in newly diagnosed refractive amblyopes, but the neural deficits do not seem to be orientation-specific for the stimulus parameters investigated.


Assuntos
Ambliopia/fisiopatologia , Potenciais Evocados Visuais/fisiologia , Orientação/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Anisotropia , Astigmatismo/fisiopatologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Humanos , Psicofísica
10.
PLoS One ; 15(5): e0233786, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32469998

RESUMO

A single experiment required 40 younger and older adults to discriminate global shape as depicted by Glass patterns (concentric and radial organizations). Such patterns have been widely used for decades, because in order to successfully perceive the depicted shape, the visual system has to detect both locally oriented features (dipoles) and their alignments across extended regions of space. In the current study, we manipulated the number of constituent dipoles in the stimulus patterns (40 or 200), the noise-to-signal ratio (zero, 1.0, & 5.0), and the pattern size (6.0 & 25.0 degrees visual angle). The observers' shape discrimination accuracies (d' values) decreased markedly as the amount of noise increased, and there were smaller (but significant) effects of both overall pattern size and the number of stimulus dipoles. Interestingly, while there was a significant effect of age, it was relatively small: the overall d' values for older and younger adults were 2.07 and 2.34, respectively. Older adults therefore retain an effective ability to visually perceive global shape, even for sparsely-defined patterns embedded in noise.


Assuntos
Envelhecimento Cognitivo/fisiologia , Sensibilidades de Contraste/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Aprendizagem por Discriminação , Percepção de Distância/fisiologia , Humanos , Pessoa de Meia-Idade , Orientação/fisiologia , Adulto Jovem
11.
PLoS One ; 15(3): e0229575, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32119712

RESUMO

In the era of smartphones, route-planning and navigation is supported by freely and globally available web mapping services, such as OpenStreetMap or Google Maps. These services provide digital maps, as well as route planning functions that visually highlight the suggested route in the map. Additionally, such digital maps contain landmark pictograms, i.e. representations of salient objects in the environment. These landmark representations are, amongst other reference points, relevant for orientation, route memory, and the formation of a cognitive map of the environment. The amount of visible landmarks in maps used for navigation and route planning depends on the width of the displayed margin areas around the route. The amount of further reference points is based on the visual complexity of the map. This raises the question how factors like the distance of landmark representations to the route and visual map complexity determine the relevance of specific landmarks for memorizing a route. In order to answer this question, two experiments that investigated the relation between eye fixation patterns on landmark representations, landmark positions, route memory and visual map complexity were carried out. The results indicate that the attentional processing of landmark representations gradually decreases with an increasing distance to the route, decision points and potential decision points. Furthermore, this relation was found to be affected by the visual complexity of the map. In maps with low visual complexity, landmark representations further away from the route are fixated. However, route memory was not found to be affected by visual complexity of the map. We argue that map users might require a certain amount of reference points to form spatial relations as a foundation for a mental representation of space. As maps with low visual complexity offer less reference points, people need to scan a wider area. Therefore, visual complexity of the area displayed in a map should be considered in navigation-oriented map design by increasing displayed margins around the route in maps with a low visual complexity. In order to verify our assumption that the amount of reference points not only affects visual attention processes, but also the formation of a mental representation of space, additional research is required.


Assuntos
Aprendizagem Espacial/fisiologia , Navegação Espacial/fisiologia , Processamento Espacial/fisiologia , Adulto , Atenção/fisiologia , Cognição/fisiologia , Feminino , Mapeamento Geográfico , Humanos , Masculino , Memória/fisiologia , Orientação/fisiologia , Percepção Espacial/fisiologia
12.
Science ; 367(6482): 1112-1119, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32139539

RESUMO

The genome versus experience dichotomy has dominated understanding of behavioral individuality. By contrast, the role of nonheritable noise during brain development in behavioral variation is understudied. Using Drosophila melanogaster, we demonstrate a link between stochastic variation in brain wiring and behavioral individuality. A visual system circuit called the dorsal cluster neurons (DCN) shows nonheritable, interindividual variation in right/left wiring asymmetry and controls object orientation in freely walking flies. We show that DCN wiring asymmetry instructs an individual's object responses: The greater the asymmetry, the better the individual orients toward a visual object. Silencing DCNs abolishes correlations between anatomy and behavior, whereas inducing DCN asymmetry suffices to improve object responses.


Assuntos
Encéfalo/crescimento & desenvolvimento , Drosophila melanogaster/crescimento & desenvolvimento , Individualidade , Neurogênese , Campos Visuais/fisiologia , Vias Visuais/crescimento & desenvolvimento , Animais , Encéfalo/anatomia & histologia , Drosophila melanogaster/genética , Variação Genética , Orientação/fisiologia , Vias Visuais/anatomia & histologia
13.
Hum Mov Sci ; 70: 102590, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32217207

RESUMO

Compound, or awkward, spine postures have been suggested as a biomechanical risk factor for low back injury. This experiment investigates the influence of head (i.e. head-on-torso) and gaze (i.e. eye-in-head) orientation on three-dimensional (3D) neck and spine range of motion (ROM) during forward flexion movements. To emulate previous experimental protocols and replicate real-world scenarios, a sample of ten young, healthy males (mean ± standard deviation: age: 20.8 ± 1.03 years, height: 180.2 ± 7.36 cm, and mass: 81.9 ± 6.47 kg) completed forward flexion movements with a constrained and unconstrained pelvis, respectively. Surface kinematics were gathered from the head and spine (C7-S1). Movements were completed under a baseline condition as well as upward, downward, leftward, and rightward head and gaze orientations. For each condition, mean neck angle and inter-segmental spine (C7T1 through L5S1) ROM were evaluated. The results demonstrate that directed head and gaze orientations can influence the ROM of specific spine regions during a forward flexion task. With leftward and rightward directed head and gaze orientations, the neck became increasingly twisted and superior thoracic segments (i.e. C7T1-T2T3) were significantly more twisted during the leftward head orientation condition than the baseline condition. With upward and downward directed head and gaze orientations, a similar effect was observed for neck and superior thoracic (i.e. C7T1-T4T5) flexion-extension. Interestingly, it was also demonstrated that changes in upward/downward head orientation can also change flexion-extension kinematics of the thoracolumbar region as well (i.e. T7T8-L1L2), suggesting that head postures requiring neck extension may also promote extension throughout these spine regions. These findings provide evidence for a functional link between changes in neck flexion-extension posture and flexion-extension movement of the thoracolumbar region of the spine.


Assuntos
Fixação Ocular/fisiologia , Cabeça/fisiologia , Orientação/fisiologia , Coluna Vertebral/fisiologia , Fenômenos Biomecânicos/fisiologia , Movimentos da Cabeça/fisiologia , Humanos , Masculino , Movimento/fisiologia , Pelve/fisiologia , Amplitude de Movimento Articular , Adulto Jovem
14.
Hum Mov Sci ; 70: 102589, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32217208

RESUMO

In trampolining, gymnasts perform a variety of rotational jumping elements and have to demonstrate perfect control of the body during the flying phase. The performance of a somersault should include an opening phase, i.e. the legs are fully extended pointing vertically at 180° called "kick-out". As previous studies have shown, gaze behavior is essential for the controlling during the flight phase and to prepare for a perfect landing. Gymnasts supposedly use the trampoline bed as orientation and differences in gaze behavior can be expected, depending on how a somersault is performed. The present study investigates the gaze behavior of gymnasts during a back tuck somersault on the trampoline. Eleven experienced trampoline gymnasts performed back tuck somersaults with and without a kick-out while wearing a light weight portable eye-tracking device. All subjects fixated their gaze on a specific point at the trampoline bed and thus used visual information to prepare for landing. During the period of fixation, gymnasts' eyes moved continuously downwards to counteract the backwards head movement. The point of fixation differed between each somersault. Apparently, the fixation position depended on the gymnast's landing position in the bed. Performing a somersault with a kick-out allows gymnasts to orient themselves earlier and thus prepare sooner for landing. Unexpectedly, gymnasts of a higher performance class fixated the bed later compared to less experienced athletes. Supposedly, gymnasts of a better class can allow themselves to fixate later in order to optimize the form and execution of a somersault.


Assuntos
Fixação Ocular/fisiologia , Ginástica/psicologia , Adulto , Atletas , Desempenho Atlético , Fenômenos Biomecânicos , Movimentos Oculares/fisiologia , Feminino , Movimentos da Cabeça/fisiologia , Humanos , Masculino , Orientação/fisiologia , Rotação , Adulto Jovem
15.
Sci Rep ; 10(1): 5422, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32214127

RESUMO

Electrocorticogram (ECoG), obtained from macroelectrodes placed on the cortex, is typically used in drug-resistant epilepsy patients, and is increasingly being used to study cognition in humans. These studies often use power in gamma (30-70 Hz) or high-gamma (>80 Hz) ranges to make inferences about neural processing. However, while the stimulus tuning properties of gamma/high-gamma power have been well characterized in local field potential (LFP; obtained from microelectrodes), analogous characterization has not been done for ECoG. Using a hybrid array containing both micro and ECoG electrodes implanted in the primary visual cortex of two female macaques (for some stimulus conditions, separate ECoG and microelectrode arrays in two additional male macaques were also used), we compared the stimulus tuning preferences of gamma/high-gamma power in LFP versus ECoG in up to four monkeys, and found them to be surprisingly similar. High-gamma power, thought to index the average firing rate around the electrode, was highest for the smallest stimulus (0.3° radius), and decreased with increasing size in both LFP and ECoG, suggesting local origins of both signals. Further, gamma oscillations were similarly tuned in LFP and ECoG to stimulus orientation, contrast and spatial frequency. This tuning was significantly weaker in electroencephalogram (EEG), suggesting that ECoG is more like LFP than EEG. Overall, our results validate the use of ECoG in clinical and basic cognitive research.


Assuntos
Eletrocorticografia/métodos , Córtex Visual/fisiologia , Potenciais de Ação/fisiologia , Animais , Mapeamento Encefálico/métodos , Feminino , Haplorrinos , Macaca , Masculino , Microeletrodos , Neurônios/fisiologia , Orientação/fisiologia , Estimulação Luminosa/métodos
16.
Dev Cogn Neurosci ; 42: 100763, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32072936

RESUMO

Multiple visual attention mechanisms are active already in infancy, most notably one supporting orienting towards stimuli and another, maintaining appropriate levels of alertness, when exploring the environment. They are thought to depend on separate brain networks, but their effects are difficult to isolate in existing behavioural paradigms. Better understanding of the contribution of each network to individual differences in visual orienting may help to explain their role in attention development. Here, we tested whether alerting and spatial cues differentially modulate pupil dilation in 8-month-old infants in a visual orienting paradigm. We found differential effects in the time course of these responses depending on the cue type. Moreover, using Principal Component Analysis (PCA) we identified two main components of pupillary response, which may reflect the alerting and orienting network activity. In a regression analysis, these components together explained nearly 40 % of variance in saccadic latencies in the spatial cueing condition of the task. These results likely demonstrate that both networks work together in 8-month-old infants and that their activity can be indexed with pupil dilation combined with PCA, but not with raw changes in pupil diameter.


Assuntos
Atenção/fisiologia , Orientação/fisiologia , Pupila/fisiologia , Feminino , Humanos , Lactente , Masculino
17.
J Vis ; 20(2): 5, 2020 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-32097482

RESUMO

Perceptual learning, which improves stimulus discrimination, typically results from training with a single stimulus condition. Two major learning mechanisms, early cortical neural plasticity and response reweighting, have been proposed. Here we report a new format of perceptual learning that by design may have bypassed these mechanisms. Instead, it is more likely based on abstracted stimulus evidence from multiple stimulus conditions. Specifically, we had observers practice orientation discrimination with Gabors or symmetric dot patterns at up to 47 random or rotating location × orientation conditions. Although each condition received sparse trials (12 trials/session), the practice produced significant orientation learning. Learning also transferred to a Gabor at a single untrained condition with two- to three-times lower orientation thresholds. Moreover, practicing a single stimulus condition with matched trial frequency (12 trials/session) failed to produce significant learning. These results suggest that learning with multiple stimulus conditions may not come from early cortical plasticity or response reweighting with each particular condition. Rather, it may materialize through a new format of perceptual learning, in which orientation evidence invariant to particular orientations and locations is first abstracted from multiple stimulus conditions and then reweighted by later learning mechanisms. The coarse-to-fine transfer of orientation learning from multiple Gabors or symmetric dot patterns to a single Gabor also suggest the involvement of orientation concept learning by the learning mechanisms.


Assuntos
Aprendizagem/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Plasticidade Neuronal/fisiologia , Orientação/fisiologia , Orientação Espacial , Adulto Jovem
18.
Nat Commun ; 11(1): 831, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-32047156

RESUMO

Visual features extracted by retinal circuits are streamed into higher visual areas (HVAs) after being processed along the visual hierarchy. However, how specialized neuronal representations of HVAs are built, based on retinal output channels, remained unclear. Here, we addressed this question by determining the effects of genetically disrupting retinal direction selectivity on motion-evoked responses in visual stages from the retina to HVAs in mice. Direction-selective (DS) cells in the rostrolateral (RL) area that prefer higher temporal frequencies, and that change direction tuning bias as the temporal frequency of a stimulus increases, are selectively reduced upon retinal manipulation. DS cells in the primary visual cortex projecting to area RL, but not to the posteromedial area, were similarly affected. Therefore, the specific connectivity of cortico-cortical projection neurons routes feedforward signaling originating from retinal DS cells preferentially to area RL. We thus identify a cortical processing stream for motion computed in the retina.


Assuntos
Neurônios/fisiologia , Retina/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Animais , Proteínas do Citoesqueleto/genética , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Percepção de Movimento/fisiologia , Orientação/fisiologia , Estimulação Luminosa , Retina/diagnóstico por imagem
19.
Acta Psychol (Amst) ; 204: 103024, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32044527

RESUMO

Research indicates that humans orient attention toward facial expressions of emotion. Orienting to facial expressions has typically been conceptualised as due to bottom-up attentional capture. However, this overlooks the contributions of top-down attention and selection history. In the present study, across four experiments, these three attentional processes were differentiated using a variation of the dot-probe task, in which participants were cued to attend to a happy or angry face on each trial. Results show that attention toward facial expressions was not exclusively driven by bottom-up attentional capture; instead, participants could shift their attention toward both happy and angry faces in a top-down manner. This effect was not found when the faces were inverted, indicating that top-down attention relies on holistic processing of the face. In addition, no evidence of selection history was found (i.e., no improvement on repeated trials or blocks of trials in which the task was to orient to the same expression). Altogether, these results suggest that humans can use top-down attentional control to rapidly orient attention to emotional faces.


Assuntos
Atenção/fisiologia , Sinais (Psicologia) , Emoções/fisiologia , Expressão Facial , Orientação/fisiologia , Estimulação Luminosa/métodos , Adolescente , Adulto , Feminino , Humanos , Masculino , Tempo de Reação/fisiologia , Adulto Jovem
20.
Infant Behav Dev ; 58: 101422, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32044581

RESUMO

Humans attend to different positions in the space either by moving their eyes or by moving covertly their attention. The development of covert attention occurs during the first year of life. According to Colombo's model of attention (2001), within the first years there is a significant change in infants' visuo-spatial orienting mechanisms, from a predominantly overt form to a covert orienting starting from 4 to 5 months of life. The use of non-invasive brain imaging techniques can shed light on the origin of such mechanisms. In particular, EEG and ERP studies can directly investigate the neural correlates of covert attention in young infants. The present study investigated the neural correlates of covert attention employing a visuo-spatial cueing paradigm in 3-month-old infants. Infants were presented with a central point-light walker (PLD) followed by a single peripheral target. The target appeared randomly at a position either congruent or incongruent with the walking direction of the cue. We examined infants' target-locked P1 component and the saccade latencies toward the peripheral target. Results showed that the P1 component was larger in response to congruent than to incongruent targets and saccade latencies were faster for congruent rather than incongruent trials. Moreover, the facilitation in processing sensory information (priming effects) presented at the cued spatial location occurs even before the onset of the oculomotor response, suggesting that covert attention is present before 4 months of age. Overall, this study highlights how ERPs method could help researchers at investigating the neural basis of attentional mechanisms in infants.


Assuntos
Atenção/fisiologia , Percepção de Movimento/fisiologia , Orientação Espacial/fisiologia , Estimulação Luminosa/métodos , Movimentos Sacádicos/fisiologia , Percepção Espacial/fisiologia , Adulto , Feminino , Humanos , Lactente , Masculino , Orientação/fisiologia , Distribuição Aleatória , Tempo de Reação/fisiologia
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