SPATIAL FLOWER PARAMETERS AND INSECT SPATIAL VISION

In environments with many concurrent sound sources, it is often possible to hear out individual sounds and identify their sources. To accomplish this perceptual organization of the sound sources, listeners analyze the mixture of sounds to estimate the constituent components that correspond to one acoustic sound source. Signal components that are likely to come from the same source are grouped into an auditory object, that is segregated from the acoustic complex. The grouping of signal components into sources is based on identifying shared features of the components, like common spectral cues (the same fundamental frequency or frequency modulation), temporal cues (the same temporal envelope), or spatial cues (the same interaural differences). When signal components’ onsets fall within such a time window that they are perceived as being synchronous, the components are combined to form a new auditory object, that is monitored across time on cues that sustain their grouping. Given that spatial cues are inherent to every sound and already present at the onset, and that they enhance detection of a sound by a spatial release from masking, it is unclear whether and how much temporal perception depends on the presence of spatial cues. The research presented here addressed the contribution of the binaural hearing system, which processes a sound’s spatial cues, to the processing of its temporal cues, and the contribution of the sounds’ temporal cues to the processing of their spatial cues. In order to assess the contribution of spatial cues to temporal perception, experiments were conducted in which the temporal position of a target sound’s onset was controlled by the subjects to find its desired position relative to a regular series of reference sound onsets. Manipulation of the target’s interaural differences, its sensation level, and the target and reference sounds’ durations allowed comparison of their effects on temporal perception of the target’s onset. The main finding was that temporal perception precision degraded below a critical level, depending on the absolute target and masker levels and the difference in spatial configuration between target and masker that facilitated perception at much lower signal-to-noise ratios. The implication of a sound’s signal-to-noise ratio getting below this critical level is that, when the temporal window for grouping signal components’ onsets is enlarged due to the degraded precision, there is an increased probability for signal components to be grouped incorrectly into an auditory object, or to be prevented from grouping into a new auditory object and remain part of the acoustic complex until other evidence is gathered for the existence of their source. This may be a contributing factor to the decrease of speech intelligibility in noisy environments, where precise temporal perception of transients is required for the processing of speech signals. In order to assess the contribution of temporal cues to binaural processing, thresholds were measured for discrimination between the spatial configurations of two sounds that had identical spectral range and onset and offset times, but differed in their temporal envelope structure and had equally-sized directional information to opposite sides of the medial plane. The measured minimum interaural differences in time or level at which the sounds’ spatial configurations could successfully be discriminated represented the ability to process binaural cues, and allowed comparison between the effects of the various manipulations of bandwidths, center frequencies, and temporal envelopes to the sounds. The main findings were that discrimination based on interaural level differences was good for all tested conditions (although absolute thresholds depended on the specific conditions), and that discrimination based on interaural time differences was only possible when the temporal envelopes of the sounds were sufficiently different. The binaural system must, therefore, have been capable of processing the interaural differences within short periods of time when one of the sounds was dominant in the monaural temporal envelopes of the combined signals at each ear. Analysis of the monaural temporal envelopes influences the ability to use the binaural information to separate individual signal components, and allow tracking across time of the signals components with identical spatial cues to form a perceptual unity, the auditory object. In conditions where discrimination was not possible, the temporal envelopes of the individual sounds were too similar and such periods did not occur systematically in the temporal envelopes of the combined sounds. This finding suggests that a monaural analysis of a composite signal’s temporal envelope is a prerequisite for the binaural processing of the constituent signal components’ interaural time differences. The implication is that, if the signals’ temporal envelopes are too similar, their signal components may not be correctly grouped into separate and individually lateralized auditory objects, but remain fused as a single object with an averaged spatial image.

Knowing when an event is likely to occur allows attentional resources to be oriented toward that moment in time, enhancing processing of the event. We previously found that children (mean age 11 years) are unable to use endogenous temporal cues to orient attention in time, despite being able to use endogenous spatial cues (arrows) to orient attention in space. Arrow cues, however, may have proved beneficial by engaging exogenous (automatic), as well as endogenous (voluntary), orienting mechanisms. We therefore conducted two studies in which the exogenous properties of visual temporal cues were increased, to examine whether this helped children orient their attention in time. In the first study, the location of an imperative target was predicted by the direction of a left or right spatial arrow cue while its onset was predicted by the relative duration of a short or long temporal cue. To minimize the influence of rhythmic entrainment in the temporal condition, the foreperiod (500 ms/1100 ms) was deliberately chosen so as not to precisely match the duration of the temporal cue (100 ms/400 ms). Targets appeared either at cued locations/onset times (valid trials) or at unexpected locations/onset times (invalid trials). Adults’ response times were significantly slower for invalid versus valid trials, in both spatial and temporal domains. Despite being slowed by invalid spatial cues, children (mean age 10.7 years) were unperturbed by invalid temporal cues, suggesting that these duration-based temporal cues did not help them orient attention in time. In the second study, we enhanced the exogenous properties of temporal cues further, by presenting multiple temporal cues in an isochronous (rhythmic) sequence. Again, to minimize automatic entrainment, target onset did not match the isochronous interval. Children (mean age 11.4 years), as well as adults, were now significantly slowed by invalid cues in both the temporal and spatial dimension. The sequential, as opposed to single, presentation of temporal cues therefore helped children to orient their attention in time. We suggest that the exogenous properties of sequential presentation provide a temporal scaffold that supports the additional attentional and mnemonic requirements of temporal, as compared to spatial, processing.

Weber ratios were obtained for visual velocity discrimination under three topographic conditions with the same subjects and psychophysical procedures. The conditions differed regarding the presence of either temporal or spatial cues, these being correlated in magnitude with stimulus velocity. Systematic effects of the cues upon the level of velocity discrimination were noted.

Video salient object detection (VSOD) aims to locate and segment the most attractive object by exploiting both spatial cues and temporal cues hidden in video sequences. However, spatial and temporal cues are often unreliable in real-world scenarios, such as low-contrast foreground, fast motion, and multiple moving objects. To address these problems, we propose a new framework to adaptively capture available information from spatial and temporal cues, which contains Confidence-guided Adaptive Gate (CAG) modules and Dual Differential Enhancement (DDE) modules. For both RGB features and optical flow features, CAG estimates confidence scores supervised by the IoU between predictions and the ground truths to re-calibrate the information with a gate mechanism. DDE captures the differential feature representation to enrich the spatial and temporal information and generate the fused features. Experimental results on four widely used datasets demonstrate the effectiveness of the proposed method against thirteen state-of-the-art methods.

The red-green axis of colour vision evolved recently in primate evolutionary history. Signals serving red-green colour vision travel together with signals serving spatial vision, in the parvocellular (PC) division of the subcortical visual pathway. However, the question of whether receptive fields of PC pathway cells are specialized to transmit red-green colour signals remains unresolved. We addressed this question in single-cell recordings from the lateral geniculate nucleus of anaesthetized marmosets. Marmosets show a high proportion of dichromatic (red-green colour-blind) individuals, allowing spatial and colour tuning properties of PC cells to be directly compared in dichromatic and trichromatic visual systems. We measured spatial frequency tuning for sine gratings that provided selective stimulation of individual photoreceptor types. We found that in trichromatic marmosets, the foveal visual field representation is dominated by red-green colour-selective PC cells. Colour selectivity of PC cells is reduced at greater eccentricities, but cone inputs to centre and surround are biased to create more selectivity than predicted by a purely 'random wiring' model. Thus, one-to-one connections in the fovea are sufficient, but not necessary, to create colour-selective responses. The distribution of spatial tuning properties for achromatic stimuli shows almost complete overlap between PC cells recorded in dichromatic and trichromatic marmosets. These data indicate that transmission of red-green colour signals has been enabled by centre-surround receptive fields of PC cells, and has not altered the capacity of PC cells to serve high-acuity vision at high stimulus contrast.

Recent works have proved that combining spatial and temporal visual cues can significantly improve the performance of various vision-based robotic systems. However, for the ultrasonic sensors used in most robotic tasks (e.g. collision avoidance, localization and navigation), there is a lack of benchmark ultrasonic datasets that consist of spatial and temporal data to verify the usability of spatial and temporal ultrasonic cues. In this paper, we are the first to propose a Spatio-Temporal Ultrasonic Dataset (STUD), which aims to develop the ability of ultrasonic sensors by mining spatial and temporal information from multiple ultrasonic measurements. In particular, we first propose a novel Spatio-Temporal (ST) ultrasonic data gathering scheme, in which an innovatory data instance is designed. Besides, part of the data in the STUD is collected in a robot simulator, in which a well-designed corridor map is utilized to increase the data diversity. Then a selection algorithm is proposed to find a proper length of data sequences to obtain the best description of the navigation environments. Finally, we present an end-to-end learning benchmark model that learns driving policies by extracting spatial and temporal ultrasonic cues from the STUD. With the help of our STUD and this benchmark model, more powerful deep neural networks can be trained for addressing the tasks of indoor navigation or motion planning of mobile robots, which is unachievable by using the existing ultrasonic datasets. Comparison experiments verified the effectiveness of spatial and temporal ultrasonic cues for the robot driving policy learning.

Previous research has demonstrated the improved target detection performance resulting from the coherent motion cues provided by a visually time-compressed radar display (Moll and Scanlan, 1972; Scanlan, Roscoe, and Williges, 1971). These studies indicate that, as the detection task becomes more difficult because of increased noise and clutter, the improvement due to time compression increases. The results of these studies further indicate that, if the spatial aspect of the target could also be enhanced, additional target detection improvement might be realized. The present study compared target detection performance on a standard time-compressed display with performance on two displays that provide both spatial and temporal target cues. A fourth display providing primarily spatial cues was also included in the comparison. The results indicate that the addition of spatial cues improves the detectability of a target under conditions of high noise and that at least five frames of storage are required for best performance.

Extracting salient regions plays an important role in computer vision tasks, e.g., object detection, recognition and video compression. Previous saliency detection study is mostly conducted on individual frames and tends to extract saliency with spatial cues. The development of various motion feature further extends the saliency concept to the motion saliency from videos. In contrast to image-based saliency extraction, video-based saliency extraction is more challenging due to the complicated distractors, e.g., the background dynamics and shadows. In this paper, we propose a novel saliency extraction method by fusing temporal and spatial cues. In specific, the long-term and short-term variations are comprehensively fused to extract the temporal cue, which is then utilized to establish the background guidance for generating the spatial cue. Herein, the long-term variations and spatial cues jointly highlight the contrast between objects and the background, which can solve the problem caused by shadows. The short-term variations contribute to the removal of background dynamics. Spatiotemporal cues are fully exploited to constrain the saliency extraction across frames. The saliency extraction performance of our method is demonstrated by comparing it to both unsupervised and supervised methods. Moreover, this novel saliency extraction model is applied in the video compression tasks, helping to accelerate the video compression task and achieve a larger PSNR value for the region of interest (ROI).

While scanning a textured surface with fingers, tactile information is encoded both spatially, by differential activation of adjacent receptors, and temporally, by changes in receptor activation during movements of the fingers across the surface. We used a tactile discrimination task to examine the dependence of human tactile perception on the availability of spatial and temporal cues. Subjects discriminated between spatial frequencies of metal gratings presented simultaneously to both hands. Tactile temporal cues were eliminated by preventing lateral hand movements; tactile spatial cues were eliminated by using gloves with an attached rubber pin. Analysis revealed separation of the subjects into two groups: "spatiotemporal" (ST) and "latent-temporal" (LT). Under normal conditions, the performance of ST subjects was significantly better than that of the LT subjects. Prevention of lateral movements impaired performance of both ST and LT subjects. However, when only temporal cues were available, the performance of ST subjects was significantly impaired, whereas that of the LT subjects either improved or did not change. Under the latter condition, LT subjects changed strategy to scanning with alternating hands, at velocities similar to the velocities normally used by ST subjects. These velocities generated temporal frequencies between 15 and 30 Hz. The LT subjects were unaware of their improved performance. Nine of ten LT subjects significantly improved their performance under normal conditions when trained to scan gratings using alternating hands and velocities similar to those used by ST subjects. We conclude that (1) temporal cues are essential for spatial-frequency discrimination, (2) human subjects vary in the tactile strategies they use for texture exploration, and (3) poor tactile performers can significantly improve by using strategies that emphasize temporal cues.

and colleagues (Hempel de Ibarra et al. 2014). Lars Chittka and colleagues specifically remind us that whilst bees and other insects see in color, in complex natural environments color perception can be a challenging cue due to the large changes in the spectral quality of light in different foraging environments (Chittka et al. 2014). Anne Leonard and Pavel Masek (2014) discuss the latest evidence that bees can use multimodal information combining both color and olfactory cues to help reduce uncertainty in complex foraging conditions. Indeed there is currently a lot of interest in how bees make decisions in complex environments. Aurore Avargues-Weber and Martin Giurfa (2014) discuss that a variety of important factors like conditioning method can influence bee perception, possibly through cognitive ‘top-down’ attention-type mechanisms. Further evidence of complex decision making in bees comes from a nice study on bumblebees by Lisa Evans and Nigel Raine (2014) who show that the way in which some bees make errors may be of adaptive advantage for selecting novel rewarding colors in natural conditions. Other studies show us that since the time of von Frisch color processing has been tested in a wide variety of different insect species. Motohiro Wakakuwa and colleagues (2014) discuss photoreceptor sensitivity in the leafhopper (Nephotettix cincticeps) which shows some behavioral sensitivity to long wavelength ‘infrared’ radiation. Francismeire Telles and colleagues (2014) show in the hummingbird hawkmoth (Macroglossum stellatarum) that the behavioral sensitivity to blue wavelength light is much higher than predicted from the retinal photoreceptor sensitivity, which may be related to the innate preference of hawkmoths for blue flowers. Besides bees, flies and butterflies have been well studied. Klaus Lunau (2014) provides a timely review on the color vision of flies which is a system generating a lot of interest at present. Michiyo Kinoshita About 100 years ago it was often thought the world might appear pretty dull for insects until the publication of Karl von Frisch in 1914. this ground breaking study by von Frisch revealed that free flying honeybees could be trained with sucrose solution to visit a colored card, and choose this stimulus correctly in tests when placed amongst a variety of grey cards. the logic of the experiment, done at a time when the spectral sensitivities of bee photoreceptors were unknown, was that if bees were only using an achromatic mechanism to find the conditioned, colored stimulus associated with a sucrose reward then the bees would make mistakes for grey cards having similar brightness values to the colored stimulus. However, the bees reliably chose the colored stimulus amongst many shades of grey (von Frisch 1914), and the eyes of the next generations of researchers were opened to the refinement and diversity of color perception in bees and other insects (Kuhn 1927; Daumer 1956; Menzel 1967; Helversen 1972; Giurfa 2004). this current year of 2014 also marks the 50th anniversary of the first publication of the spectral sensitivities of individual photoreceptor cells in the honeybee by Autrum and von Zwehl (1964), which further helped to establish honeybees as a classic model for research into insect color vision (Peitsch et al. 1992; Briscoe and Chittka 2001). In this special issue of The Journal of Comparative Physiology A, leading scientists in the field have teamed up to pay tribute to the important start Karl von Frisch gave to the field of neuroethology and insect vision with his publication in 1914. Basic physiology and ecology of bee color vision is summarized by Natalie Hempel de Ibarra

This year marks the inauguration of the annual Editors' Choice Award and the Readers' Choice Award, each presented for outstanding original papers and review articles published in the Journal of Comparative Physiology A. The winners of the 2022 Editors' Choice Award were determined by vote of the Editorial Board for the most highly recommended papers published in Volume 207 in 2021. They are 'Visual discrimination and resolution in freshwater stingrays (Potamotrygon motoro)' by Daniel et al. (J Comp Physiol A 207, 43-58, 2021) in the Original Paper category; and 'Neurophysiology goes wild: from exploring sensory coding in sound proof rooms to natural environments' by Römer (J Comp Physiol A 207, 303-319, 2021) in the Review Article category. The 2022 Readers' Choice Award was based on access number of articles published in Volume 206 in 2020, to ensure at least 12-month online presence. It is given to Nicholas et al. for their original paper titled 'Visual motion sensitivity in descending neurons in the hoverfly' (J Comp Physiol A 206, 149-163, 2020); and to Schnaitmann et al. for their review article entitled 'Color vision in insects: insights from Drosophila' (J Comp Physiol A 206, 183-198, 2020).

Light fields in the real world are highly complex because they contain multiple illumination sources, including indirect light reflected from other surfaces. Such interreflexions are well compensated by the human visual system, by employing prior knowledge about the nature of the light field (Mach-card experiment: Bloj et al., 1999). Interreflections are the rule in natural environments and therefore a general problem for all organisms relying on colour vision, e.g. bees. Honeybees have excellent colour constancy as demonstrated for flat Mondrian-like scenes (Werner et al., 1988). However, bees have far fewer neurons available for these operations than humans and it is therefore interesting to ask: how can a complex colour vision task, like compensating the effect of light fields in 3D scenes, be solved by a relatively simple system? I will present a Mach-card experiment with free-flying honeybees (apis mellifera), where individual bees were trained to discriminate between green/white cards folded in different spatial configurations: (1) planar (2) concave and (3) convex. The stimuli (paper cards, 2.5 x 2.5 x 6 cm) were presented in front of a vertical, "grey" background (a turntable disc, 80 cm diameter). Previous experiments had shown that bees are able to resolve the depth profile of similar 3D forms. The results show that the bees recognized a trained green/white pattern irrespective of its spatial configuration, in other words, bees compensated the occurring interreflexions. Further experiments, involving simulations of the interreflexions, showed that the compensation depends on the consistency of spatial and chromatic cues. This suggests that bees use their knowledge about the spatial configuration in 3D scenes in order to discount the effects of mutual illuminations. Whether this involves cognitive inference, as it suggested for human colour vision, or is driven by hard-wired interconnections, remains to be solved. Meeting abstract presented at VSS 2014

Opsin proteins covalently bind to small molecular chromophores and each protein-chromophore complex is sensitive to particular wavelengths of light. Multiple opsins with different wavelength absorbance peaks are required for color vision. Comparing opsin responses is challenging at low light levels, explaining why color vision is often lost in nocturnal species. Here, we investigated opsin evolution in 27 phylogenetically diverse insect species including several transitions between photic niches (nocturnal, diurnal, and crepuscular). We find widespread conservation of five distinct opsin genes, more than commonly considered. These comprise one c-opsin plus four r-opsins (long wavelength sensitive or LWS, blue sensitive, ultra violet [UV] sensitive and the often overlooked Rh7 gene). Several recent opsin gene duplications are also detected. The diversity of opsin genes is consistent with color vision in diurnal, crepuscular, and nocturnal insects. Tests for positive selection in relation to photic niche reveal evidence for adaptive evolution in UV-sensitive opsins in day-flying insects in general, and in LWS opsins of day-flying Lepidoptera specifically.

This combined fMRI and MEG study investigated brain activations during listening and attending to natural auditory scenes. We first recorded, using in-ear microphones, vocal non-speech sounds, and environmental sounds that were mixed to construct auditory scenes containing two concurrent sound streams. During the brain measurements, subjects attended to one of the streams while spatial acoustic information of the scene was either preserved (stereophonic sounds) or removed (monophonic sounds). Compared to monophonic sounds, stereophonic sounds evoked larger blood-oxygenation-level-dependent (BOLD) fMRI responses in the bilateral posterior superior temporal areas, independent of which stimulus attribute the subject was attending to. This finding is consistent with the functional role of these regions in the (automatic) processing of auditory spatial cues. Additionally, significant differences in the cortical activation patterns depending on the target of attention were observed. Bilateral planum temporale and inferior frontal gyrus were preferentially activated when attending to stereophonic environmental sounds, whereas when subjects attended to stereophonic voice sounds, the BOLD responses were larger at the bilateral middle superior temporal gyrus and sulcus, previously reported to show voice sensitivity. In contrast, the time-resolved MEG responses were stronger for mono- than stereophonic sounds in the bilateral auditory cortices at ~360 ms after the stimulus onset when attending to the voice excerpts within the combined sounds. The observed effects suggest that during the segregation of auditory objects from the auditory background, spatial sound cues together with other relevant temporal and spectral cues are processed in an attention-dependent manner at the cortical locations generally involved in sound recognition. More synchronous neuronal activation during monophonic than stereophonic sound processing, as well as (local) neuronal inhibitory mechanisms in the auditory cortex, may explain the simultaneous increase of BOLD responses and decrease of MEG responses. These findings highlight the complimentary role of electrophysiological and hemodynamic measures in addressing brain processing of complex stimuli.

Neural stem cells generate diverse cell types by integrating spatial and temporal cues to activate neuron-specific terminal selector (TS) genes. In Drosophila neuroblasts (NBs), spatial patterning sets lineage identity, while a temporal transcription factor (TTF) cascade sets birth order. Two proposed mechanisms could integrate these inputs. In direct regulation, spatial transcription factors (STFs) and TTFs co-occupy and activate TS enhancers within NBs. In epigenetic regulation, STFs first prime NB-specific chromatin, creating ‘sites of integration’ (SoIs) that later recruit TTFs.We test this in two identified NBs — NB5-6 and NB7-4 — and their candidate STFs, Gooseberry (Gsb) and Engrailed (En), together with the first TTF, Hunchback (Hb). In NB5-6, Gsb is expressed transiently, suggesting a chromatin-based memory of its activity. In NB7-4, En expression persists throughout development so integration could either be epigenetic or direct. We used chromatin engagement by the STFs as the discriminator between these models. If integration is epigenetic, the STF must engage less-accessible chromatin to establish NB-specific SoIs; if regulation is direct, the STF need not.We find that En binds only to pre-accessible loci in NB7-4 and En+Hb co-binding marks the most accessible enhancers. This suggests that NB7-4 likely relies on an unknown priming factor to establish SoIs, with direct En–Hb co-binding mediating enhancer activation.In NB5-6, Gsb binds both open and less-accessible chromatin and Gsb+Hb co-binding marks the most accessible enhancers. When ectopically expressed, Gsb remodels chromatin globally in the non-cognate NB7-4, and at endogenous NB7-4 SoIs, it specifically reduces accessibility as well as Hb binding. This suggests that in NB5-6 Gsb likely acts together with other NB5-6–specific factors to recognize less-accessible chromatin and to promote Hb recruitment while restricting Hb occupancy to appropriate enhancers. Together these findings support a unified two-step model: NB-specific combinations of TFs — each NB’s “STF code” — first prime chromatin and then recruit and restrict Hb to ensure lineage-specific enhancer activation.