Combination Of Sensory Cues Research Articles

Communication networks and loser effects interact to influence the outcome of aggressive interactions in the crayfish Orconectes rusticus

[Dyadic interactions occur in the vicinity of non-participating animals such that bystanders have the potential to extract relevant information about future opponents. Individuals within communication networks can use information to modify their behaviour in future encounters with a previous fighter. Previous research on crayfish ( Orconectes rusticus ) has shown that watching fights negatively impacts the ability of bystanders to win against naive opponents. We examined the role of visual information in communication networks and previous social history, in the form of winner and loser effects, in shaping crayfish aggression and outcomes of aggressive encounters. Experimental treatments consisted of allowing a bystander to observe a fight and then engaging that bystander with either the winner or loser in a subsequent encounter. Our results indicate that previous social history is more influential in determining fight outcome than information gathered via visual signals. Specifically, loser effects have a greater influence on fight dynamics than elements of communication networks. Since crayfish use a combination of sensory cues during social interactions, visual information may not provide the proper context for information use in subsequent interactions. We conclude that previous social history may be masking any effects that visual communication networks have on agonistic behaviour in crayfish., Dyadic interactions occur in the vicinity of non-participating animals such that bystanders have the potential to extract relevant information about future opponents. Individuals within communication networks can use information to modify their behaviour in future encounters with a previous fighter. Previous research on crayfish ( Orconectes rusticus ) has shown that watching fights negatively impacts the ability of bystanders to win against naive opponents. We examined the role of visual information in communication networks and previous social history, in the form of winner and loser effects, in shaping crayfish aggression and outcomes of aggressive encounters. Experimental treatments consisted of allowing a bystander to observe a fight and then engaging that bystander with either the winner or loser in a subsequent encounter. Our results indicate that previous social history is more influential in determining fight outcome than information gathered via visual signals. Specifically, loser effects have a greater influence on fight dynamics than elements of communication networks. Since crayfish use a combination of sensory cues during social interactions, visual information may not provide the proper context for information use in subsequent interactions. We conclude that previous social history may be masking any effects that visual communication networks have on agonistic behaviour in crayfish.]

Multisensory Integration in Macaque Visual Cortex Depends on Cue Reliability

Responses of multisensory neurons to combinations of sensory cues are generally enhanced or depressed relative to single cues presented alone, but the rules that govern these interactions have remained unclear. We examined integration of visual and vestibular self-motion cues in macaque area MSTd in response to unimodal as well as congruent and conflicting bimodal stimuli in order to evaluate hypothetical combination rules employed by multisensory neurons. Bimodal responses were well fit by weighted linear sums of unimodal responses, with weights typically less than one (subadditive). Surprisingly, our results indicate that weights change with the relative reliabilities of the two cues: visual weights decrease and vestibular weights increase when visual stimuli are degraded. Moreover, both modulation depth and neuronal discrimination thresholds improve for matched bimodal compared to unimodal stimuli, which might allow for increased neural sensitivity during multisensory stimulation. These findings establish important new constraints for neural models of cue integration.

How do ectoparasitic nycteribiids locate their bat hosts?

Nycteribiids (Diptera: Nycteribiidae) are specific haematophagous ectoparasites of bats, which spend nearly all their adult lives on hosts. However, females have to leave bats to deposit their larva on the walls of the roosts, where they later emerge as adult flies. Nycteribiids had thus to evolve efficient sensorial mechanisms to locate hosts from a distance. We studied the sensory cues involved in this process, experimentally testing the role of specific host odours, and general cues such as carbon dioxide, body heat, and vibrations. As models we used two nycteribiids (Penicillidia conspicua and Penicillidia dufourii) and their primary bat hosts (Miniopterus schreibersii and Myotis myotis, respectively). Carbon dioxide was the most effective cue activating and orientating the responses of nycteribiids, followed by body heat and body odours. They also responded to vibration, but did not orientate to its source. In addition, sensory cues combined (carbon dioxide and body heat) were more effective in orientating nycteribiids than either cue delivered alone. Results suggest that nycteribids have some capacity to distinguish specific hosts from a distance, probably through their specific body odours. However, the strong reliance of nycteribiids on cues combined indicates that they follow these to orientate to nearby multispecies bat clusters, where the chances of finding their primary hosts are high. The combination of sensory cues seems therefore an effective strategy used by nycteribiids to locate bat hosts at a distance.

Causal Inference in Multisensory Perception

Perceptual events derive their significance to an animal from their meaning about the world, that is from the information they carry about their causes. The brain should thus be able to efficiently infer the causes underlying our sensory events. Here we use multisensory cue combination to study causal inference in perception. We formulate an ideal-observer model that infers whether two sensory cues originate from the same location and that also estimates their location(s). This model accurately predicts the nonlinear integration of cues by human subjects in two auditory-visual localization tasks. The results show that indeed humans can efficiently infer the causal structure as well as the location of causes. By combining insights from the study of causal inference with the ideal-observer approach to sensory cue combination, we show that the capacity to infer causal structure is not limited to conscious, high-level cognition; it is also performed continually and effortlessly in perception.

Development of Multisensory Neurons and Multisensory Integration in Cat Superior Colliculus

The development of multisensory neurons and multisensory integration was examined in the deep layers of the superior colliculus of kittens ranging in age from 3 to 135 d postnatal (dpn). Despite the high proportion of multisensory neurons in adult animals, no such neurons were found during the first 10 d of postnatal life. Rather, all sensory-responsive neurons were unimodal. The first multisensory neurons (somatosensory-auditory) were found at 12 dpn, and visually responsive multisensory neurons were not found until 20 dpn. Early multisensory neurons responded weakly to sensory stimuli, had long latencies, large receptive fields, and poorly developed response selectivities. Most surprising, however, was their inability to integrate combinations of sensory cues to produce significant response enhancement (or depression), a characteristic feature of the adult. Responses to combinations of sensory cues differed little from responses to their modality-specific components. At 28 dpn an abrupt physiological change was noted. Some multisensory neurons now integrated combinations of cross-modality cues and exhibited significant response enhancements when these cues were spatially coincident and response depressions when the cues were spatially disparate. During the next 2 months the incidence of multisensory neurons, and the proportion of these neurons capable of adult-like multisensory integration, gradually increased. Once multisensory integration appeared in a given neuron, its properties changed little with development. Even the youngest integrating neurons showed superadditive enhancements and spatial characteristics of multisensory integration that were indistinguishable from the adult. Nevertheless, neonatal and adult multisensory neurons differed in the manner in which they integrated temporally asynchronous stimuli, a distribution that may reflect the very different behavioral requirements at different ages. The possible maturational role of corticotectal projections in the abrupt gating of multisensory integration is discussed.

Studies of Maternal Retrieving in Rats. Iii. Sensory Cues Involved in the Lactating Female's Response To Her Young 1)

Twenty-six lactating female rats were observed in a series of tests designed to identify the sensory cues involved in the retrieving of young to the nest. In some instances females were surgically deprived of one or more sensory receptors. In other cases the females were unoperated and the sensory qualities of the young were modified. The types of desensitization employed were enucleation of the eyes, cauterization of the olfactory bulbs, and transection of the sensory nerves serving the anterior portion of the head, including the snout and lips. Modification of sensory qualities of the young was achieved in different instances by spraying living young with oil of lavender, coating young with vasoline or collodion, killing the young just before the test by separation of the brain and spinal cord, and chilling freshly killed young in a refrigerator. In some tests living young were enclosed in glass vials so that they were visually accessible to the female but could not be smelled or touched. In other tests normal young were confined inside a small, wire-mesh cage so that the female could smell them but could not establish physical contact. In addition to normal or artificially modified young, other retrievable objects were offered to the experimental females. These included young mice and rabbits, and pieces of fresh meat cut to the size of a newborn rat. The results of these various procedures led to the conclusion that the retrieving response is ordinarily governed by a combination of sensory cues. When they are available, visual, chemical, tactile and thermal sensations all contribute to the female's tendency to approach, pick up and retrieve her offspring. No single type of sensation is indispensable. It appears that the female's retrieving behavior, like the sexual behavior of the male rat or like the maze-learning performance of both sexes, normally involves multisensory controls. This finding is believed to be related to the fact that the cerebral cortex plays an important role in the male's copulatory behavior, the female's maternal performance and in maze learning. It is probably the intervention of a cortical component which makes the rat's maternal behavior different from analogous reactions in lower vertebrates. In the latter, much of the reproductive activity seems to be controlled by relatively simple, unisensory forms of stimulation. This could be due to the fact that in these lower forms a higher nervous mechanism such as the cortex is lacking.