Disparate Cues Research Articles

Mycobacterium tuberculosis response to cholesterol is integrated with environmental pH and potassium levels via a lipid metabolism regulator.

Successful colonization of the host requires Mycobacterium tuberculosis (Mtb) to sense and respond coordinately to disparate environmental cues during infection and adapt its physiology. However, how Mtb response to environmental cues and the availability of key carbon sources may be integrated is poorly understood. Here, by exploiting a reporter-based genetic screen, we have unexpectedly found that overexpression of transcription factors involved in Mtb lipid metabolism altered the dampening effect of low environmental potassium concentrations ([K+]) on the pH response of Mtb. Cholesterol is a major carbon source for Mtb during infection, and transcriptional analyses revealed that Mtb response to acidic pH was augmented in the presence of cholesterol and vice versa. Strikingly, deletion of the putative lipid regulator mce3R had little effect on Mtb transcriptional response to acidic pH or cholesterol individually, but resulted specifically in loss of cholesterol response augmentation in the simultaneous presence of acidic pH. Similarly, while mce3R deletion had little effect on Mtb response to low environmental [K+] alone, augmentation of the low [K+] response by the simultaneous presence of cholesterol was lost in the mutant. Finally, a mce3R deletion mutant was attenuated for growth in foamy macrophages and for colonization in a murine infection model that recapitulates caseous necrotic lesions and the presence of foamy macrophages. These findings reveal the critical coordination between Mtb response to environmental cues and cholesterol, a vital carbon source, and establishes Mce3R as a transcription factor that crucially serves to integrate these signals.

Abstract 1457: Akt phosphorylation of mitochondrial Lonp1 protease enables oxidative metabolism and advanced tumor traits

Abstract Introduction: The control of protein homeostasis, or proteostasis is essential for cellular adaptation to disparate environmental cues and relies on protein (re)folding or proteolytic removal of aggregated or misfolded proteins. Defective proteostasis can irreversibly impair organelle functions and activate cell death through an unfolded protein response. Tumor mitochondria have heightened protein folding quality control, but the regulators of this process and how they impact cancer traits are not completely understood. In this study, we investigated the mechanisms of stress-regulated LonP1 (ATP-dependent protease) in tumor mitochondria and their implications for advanced cancer traits. Experimental procedures: We monitored kinase activity in immunoprecipitation, protein expression by immunoblotting, mitochondrial ROS quantification in live cells, mitochondrial electron transport chain (ETC) activity, mitochondria time-lapse video microscopy, protein folding, proteomics analysis, mitochondrial bioenergetics, mitochondrial trafficking and tumor cell motility, and tumor growth and metastasis. A xenograft prostate cancer model was used to study antitumor activity in vivo. Results: We showed that the ATP-directed mitochondrial protease, LonP1 is upregulated by stress conditions, including hypoxia, in tumor, but not normal cells. In mitochondria, LonP1 is phosphorylated by Akt on Ser173 and Ser181, enhancing its protease activity. Interference with this pathway induces accumulation of misfolded subunits of electron transport chain complex II and complex V, resulting in impaired oxidative bioenergetics and heightened ROS production. Functionally, this suppresses mitochondrial trafficking to the cortical cytoskeleton, shuts off tumor cell migration and invasion, and inhibits primary and metastatic tumor growth, in vivo. Conclusion: These data identify LonP1 as a key effector of mitochondrial reprogramming in cancer and potential therapeutic target. Citation Format: Jagadish C. ghosh, Jae Ho Seo, Ekta Agarwal, Yuan Wang, Andrew V. Kossenkov, Hsin-Yao Tang, David W. Speicher, Dario C. Altieri. Akt phosphorylation of mitochondrial Lonp1 protease enables oxidative metabolism and advanced tumor traits [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1457.

An effect of multisensory training on visual processing (Commentary on Grasso etal. (2016)).

An effect of multisensory training on visual processing (Commentary on Grasso etal. (2016)).

The insect central complex

Hordes of tourists flock to Washington, D.C. every spring to see the cherry trees blossom. Once in the city, they must find their way to the Tidal Basin where the Japanese trees grow. Fortunately, a number of visual landmarks can help them to navigate. In 1910, the United States Congress passed The Height of Buildings Act, limiting the elevation of commercial and residential structures in D.C. to 130 feet. Thus, the 555-foot-tall Washington Monument often looms large against the horizon, serving as an anchor point to help set the tourists' sense of direction. Once their heading is set, they can lose sight of the monument behind buildings or groups of tall Scandinavian visitors and still use their internal compass to navigate to the Basin. This compass keeps track of their paces and turns and updates their sense of where they are and where they need to go. Yet while their heading informs their actions, it does not dictate them. Tourists who have been to D.C. in the past can, for example, use remembered views to alter their routes to avoid crowds. On an even finer scale, their leg movements also depend on their current state - they might increase the frequency and length of their strides if hunger pangs compete with their desire to see cherry blossoms, for example. The way in which these disparate cues and motivations influence exploration is a neuroscience mystery across creatures large and small.

Intelligibility for Binaural Speech with Discarded Low-SNR Speech Components.

Speech intelligibility in multitalker settings improves when the target speaker is spatially separated from the interfering speakers. A factor that may contribute to this improvement is the improved detectability of target-speech components due to binaural interaction in analogy to the Binaural Masking Level Difference (BMLD). This would allow listeners to hear target speech components within specific time-frequency intervals that have a negative SNR, similar to the improvement in the detectability of a tone in noise when these contain disparate interaural difference cues. To investigate whether these negative-SNR target-speech components indeed contribute to speech intelligibility, a stimulus manipulation was performed where all target components were removed when local SNRs were smaller than a certain criterion value. It can be expected that for sufficiently high criterion values target speech components will be removed that do contribute to speech intelligibility. For spatially separated speakers, assuming that a BMLD-like detection advantage contributes to intelligibility, degradation in intelligibility is expected already at criterion values below 0 dB SNR. However, for collocated speakers it is expected that higher criterion values can be applied without impairing speech intelligibility. Results show that degradation of intelligibility for separated speakers is only seen for criterion values of 0 dB and above, indicating a negligible contribution of a BMLD-like detection advantage in multitalker settings. These results show that the spatial benefit is related to a spatial separation of speech components at positive local SNRs rather than to a BMLD-like detection improvement for speech components at negative local SNRs.

Telomere dysfunction reduces microglial numbers without fully inducing an aging phenotype

The susceptibility of the aging brain to neurodegenerative disease may in part be attributed to cellular aging of the microglial cells that survey it. We investigated the effect of cellular aging induced by telomere shortening on microglia by the use of mice lacking the telomerase RNA component (TERC) and design-based stereology. TERC knockout (KO) mice had a significantly reduced number of CD11b+ microglia in the dentate gyrus. Because of an even greater reduction in dentate gyrus volume, microglial density was, however, increased. Microglia in TERC KO mice maintained a homogenous distribution and normal expression of CD45 and CD68 and the aging marker, ferritin, but were morphologically distinct from microglia in both adult and old wild-type mice. TERC KO mice also showed increased cellular apoptosis and impaired spatial learning. Our results suggest that individual microglia are relatively resistant to telomerase deficiency during steady state conditions, despite an overall reduction in microglial numbers. Furthermore, telomerase deficiency and aging may provide disparate cues leading to distinct changes in microglial morphology and phenotype.

GPR109a: The Missing Link between Microbiome and Good Health?

A complex partnership between the host and the vast intestinal microbial ecosystem serves numerous biological activities including nutrition, immunity, and barrier function. In this issue of Immunity, Singh et al. (2014) demonstrate that microbial-derived butyrate mediated its protective activity against inflammation and colorectal cancer through GPR109a signaling.

The emergence of choice: Decision-making and strategic thinking through analogies

Consider the chess game: When faced with a complex scenario, how does understanding arise in one’s mind? How does one integrate disparate cues into a global, meaningful whole? How do players avoid the combinatorial explosion? How are abstract ideas represented? The purpose of this paper is to propose a new computational model of human chess cognition. We suggest that analogies and abstract roles are crucial to understanding a chess scenario. We present a proof-of-concept model, in the form of a computational architecture, which accounts for many crucial aspects of human play, such as (i) concentration of attention to relevant aspects, (ii) how humans may avoid the combinatorial explosion, (iii) perception of similarity at a strategic level, (iv) a state of meaningful anticipation over how a global scenario may evolve, and (v) the architecture’s choice as an emergent phenomenon from the actions of subcognitive processes.

Binocular interactions underlying the classic optomotor responses of flying flies

In response to imposed course deviations, the optomotor reactions of animals reduce motion blur and facilitate the maintenance of stable body posture. In flies, many anatomical and electrophysiological studies suggest that disparate motion cues stimulating the left and right eyes are not processed in isolation but rather are integrated in the brain to produce a cohesive panoramic percept. To investigate the strength of such inter-ocular interactions and their role in compensatory sensory–motor transformations, we utilize a virtual reality flight simulator to record wing and head optomotor reactions by tethered flying flies in response to imposed binocular rotation and monocular front-to-back and back-to-front motion. Within a narrow range of stimulus parameters that generates large contrast insensitive optomotor responses to binocular rotation, we find that responses to monocular front-to-back motion are larger than those to panoramic rotation, but are contrast sensitive. Conversely, responses to monocular back-to-front motion are slower than those to rotation and peak at the lowest tested contrast. Together our results suggest that optomotor responses to binocular rotation result from the influence of non-additive contralateral inhibitory as well as excitatory circuit interactions that serve to confer contrast insensitivity to flight behaviors influenced by rotatory optic flow.

Judging a Book by Its Cover: The Differential Impact of Attractiveness on Predicting One's Acceptance to High- or Low-Status Social Groups

Emerging research suggests that the cues we glean from first impressions depend on our goals. This research uses sorority recruitment to examine whether groups that vary in social status rely on disparate cues to form first impressions of potential new group members. Current sorority members were given 500 ms to view pictures of women who wanted to join their sororities, and were then asked how likely it was that each prospective member would receive a bid from their sorority (bid expectancy). Prospective members were also rated on their attractiveness. Data were analyzed separately for high- vs. low-status houses. Results revealed that attractiveness was more predictive of liking and bid expectancy for the high-status houses, as compared to the low-status houses.

Inaccurate or disparate temperature cues? Seasonal acclimation of terrestrial and aquatic locomotor capacity in newts

Summary 1. Many organisms respond to seasonal temperature fluctuations by the reversible modification of whole‐animal performance. Semiaquatic ectotherms, which possess this acclimatory capacity in swimming speed, lack the plastic response in terrestrial locomotor performance and vice versa. Theory predicts that the presence of reversible (seasonal) thermal acclimation or fixed phenotypes depends on the predictability of future thermal conditions (i.e. accuracy of temperature cues) in a given environment. Alternatively, comparative data suggest that thermal acclimation is induced by disparate temperature cues in water and on land. 2. We tested both predictions by examining the seasonal acclimation response in thermal sensitivity of maximal swimming and running speed in adult alpine newts, Ichthyosaura (formerly Triturus) alpestris. 3. Following the seasonal variation in environmental temperatures, we exposed newts to 5 °C from November to March and, after a gradual temperature increase, to either a constant (15 °C) or fluctuating (10–20 °C) thermal regime from May to June. At the end of each treatment, we measured newt swimming and running capacity at five temperatures (range 5–25 °C). In the field, hourly temperatures were recorded in various aquatic and terrestrial microhabitats to obtain information about the predictability of thermal conditions in both environments. 4. Seasonal acclimation shaped the thermal sensitivity of swimming speed under both constant and fluctuating temperature treatments. Thermal sensitivity of running speed was markedly modified by a fluctuating thermal regime so that newts ran at the highest test temperature faster than cold‐acclimated individuals. Natural thermal environment contained a similar proportion of predictable variation in water and on land. 5. Complex seasonal acclimation of locomotor capacity in newts was influenced by the disparate thermal cues, i.e. mean acclimation temperature or diel temperature fluctuations, rather than by the different accuracy of these cues in water and on land. Future confrontations of theory with empirical data will require more attention not only on the assumptions of adaptive thermal acclimation but also on the ecologically relevant thermal conditions during acclimation experiments.

Multimodal communication and spatial binding in pied currawongs (Strepera graculina)

To make accurate assessments about their environment, animals must integrate a variety of sensory cues into a single unified percept. The effects of redundant multimodal signaling may be equivalent to the responses elicited by each individual cue, or enhanced when cues are combined. Binding of two seemingly coupled cues can persist despite small spatial and temporal discrepancies in signal presentation, a phenomenon termed the ventriloquist effect. Our study had two aims: first, to test the cognitive ability of a territorial, forest-dwelling bird to bind two spatially disparate cues; and second, to define the processing of the acoustic and visual cues as having either equivalent or enhanced effects when presented together. We broadcasted pied currawong (Strepera graculina) vocalizations alone or in the presence of a model currawong situated either adjacent to, or far away from a speaker, to free-living currawongs. The number of locomotive events and the average standard deviation in the distance from the speaker maintained by the focal currawong were greater in response to "far" than "close" treatments. Additionally, the average standard deviation of the distance to speaker for the uni-modal, speaker only treatment was similar to "far" responses. These findings support our hypothesis that currawongs cognitively bind two stimuli in close spatial proximity. In nature, this would result in an enhanced level of response toward territorial intruders. Our study was novel in its attempt to assess cognitive processes involved in the integration of spatially disparate bimodal signaling events in free-living birds.

Release from interference in auditory working memory for pitch

The purpose of this study was to quantify the effect of interpolated tones upon a pitch standard held within auditory working memory through measurement of the difference limen (just noticeable difference) for frequency and the usefulness of “Where” cues to ameliorate the interference produced by these intervening stimuli. To this end, we measured the degree to which tones, containing identical and disparate localization cues, presented within the retention interval altered differential sensitivity for frequency via the method of constant stimuli. The difference limen for frequency nearly tripled when tones were presented within the retention interval and sound localization cues produced a significant partial release from interference within the short-term pitch store. Interference produced by “Where” cues ranged from 4.0 to 5.2 Hz. These findings indicate that there is a possible integrative use of the “What” and “Where” pathways in forming and maintaining pitch information within the pitch array within auditory working memory.

The Value of Pooling "Naive" Expertise: Comment.

We read with great interest the article by Westen and Weinberger (October 2004) exploring the benefits and limitations of clinical observation and judgment. They make a persuasive case for using statistical methods to aggregate clinicians’ observations in clinical and personality research. Just as increasing the number of items on an assessment instrument can improve reliability, statistically aggregating the judgments of multiple observers is likely to yield a judgment more reliable than that of a single observer. The advantages of pooling multiple observations, however, are not limited to research in clinical and personality psychology. Westen and Weinberger identify two categories of informants—clinicians and participants—but these categories could be expanded to include other observers who might have particular expertise or experience related to the phenomenon of interest. The type of expert best suited to provide observations depends on the type of expertise required. For reports about subjective psychological or physical experience, the individual himor herself is likely to be most expert. For assessment of clinically observable phenomena, clinicians may indeed bring value-added expertise. There are some domains, however, in which those with the greatest expertise are neither specially trained observers nor selfreporters but, rather, lay observers who have a native or learned ability to detect complicated social or psychological phenomena and make subtle discriminations. This type of expertise is often thought of as intuitive because it uses implicit knowledge that is not always accessible to conscious awareness or capable of being fully articulated. One way to harness this intuitive expertise effectively is to pool the judgments of multiple lay observers. Using lay expertise in observational research runs counter to the prevailing belief that manualized coding systems are required to obtain valid, reliable, and reproducible results. To be sure, manualized approaches have contributed greatly to research in psychology. However, some phenomena do not lend themselves easily to codification and rule-driven observation. For example, emotions, power dynamics, validation, and empathy have all been shown to be of great relevance to interpersonal functioning, but these are challenging to operationalize. Yet they are phenomena that individuals routinely evaluate in their everyday interactions with others. When using manual-based systems, coders may find that the rules and procedures designed to facilitate rating of these constructs do not fully utilize—and may even interfere with—the natural decoding expertise that they have developed. Needing, for example, to process all of the information in a manual and simultaneously attend to the behavioral segment being coded may overload the cognitive capacities of many individuals and interfere with their ability to utilize important cues. Consider the example of assessing emotion. Because it is socially adaptive to do so, most human beings develop a sophisticated and almost instantaneous ability to recognize others’ emotions. People use complex internal algorithms to synthesize disparate cues about emotion from body language, facial expression, vocal qualities, speech content, and social context. Of course, individual differences in this proficiency exist. Just as aggregating judgments across clinicians removes idiosyncratic biases and yields a more reliable composite judgment, aggregating the individual judgments of multiple untrained judges yields similar benefits. Our research has led us to believe that lay observers’ intuitive judgments about emotions may in fact capture important information that is lost when coders depend on more commonly used manualized approaches such as the Specific Affect Coding System (SPAFF; Gottman, McCoy, Coan, & Collier, 1996) and the Facial Action Coding System (Ekman & Friesen, 1978). In our laboratory, we experimented for a year with manualized approaches to coding emotion and then decided to explore the utility of what is often (though perhaps misleadingly) termed naive coding. Inspired by the work of Rosenthal and colleagues on coding nonverbal behaviors (e.g., Ambady & Rosenthal, 1993), we provided untrained, unmarried college-age individuals a list of 16 emotion descriptors without instructing them on how to interpret these descriptors or on markers of specific emotions. We asked them to watch videotapes of 10-min couple interactions and to code the emotional expression of each partner. For each 30-s segment of the interaction, coders rated the intensity with which each of the 16 emotions was displayed. Despite the fact that each rater coded in slightly idiosyncratic ways, we obtained good reliabilities on factor-analytically derived scales by combining the ratings of 5–6 coders. The aggregated ratings of these “naive” coders were linked in expected ways with concurrent marital satisfaction and independent assessments of marital adjustment. More important, they predicted with more than 80% accuracy a real-world consequence of great significance: whether couples in committed relationships would remain together after 5 years (Waldinger, Schulz, Hauser, Allen, & Crowell, 2004). When we compared emotion ratings of couple interactions using this approach with ratings of the same interactions by experienced coders using the manualized SPAFF, we found a high degree of correlation between the two sets of ratings (Waldinger et al., 2004). We also

Two corticotectal areas facilitate multisensory orientation behavior.

It had previously been shown that influences from two cortical areas, the anterior ectosylvian sulcus (AES) and the rostral lateral suprasylvian sulcus (rLS), play critical roles in rendering superior colliculus (SC) neurons capable of synthesizing their cross-modal inputs. The present studies examined the consequences of selectively eliminating these cortical influences on SC-mediated orientation responses to cross-modal stimuli. Cats were trained to orient to a low-intensity modality-specific cue (visual) in the presence or absence of a neutral cue from another modality (auditory). The visual target could appear at various locations within 45 degrees of the midline, and the stimulus effectiveness was varied to yield an average of correct orientation responses of approximately 45%. Response enhancement and depression were observed when the auditory cue was coupled with the target stimulus: A substantially enhanced probability in correct responses was evident when the cross-modal stimuli were spatially coincident, and a substantially decreased response probability was obtained when the stimuli were spatially disparate. Cryogenic blockade of either AES or rLS disrupted these behavioral effects, thereby eliminating the enhanced performance in response to spatially coincident cross-modal cues and degrading the depressed performance in response to spatially disparate cross-modal cues. These disruptive effects on targets contralateral to the deactivated cortex were restricted to multisensory interactive processes. Orientation to modality-specific targets was unchanged. Furthermore, the pattern of orientation errors was unaffected by cortical deactivation. These data bear striking similarities to the effects of AES and rLS deactivation on multisensory integration at the level of individual SC neurons. Presumably, eliminating the critical influences from AES or rLS cortex disrupts SC multisensory synthesis that, in turn, disables SC-mediated multisensory orientation behaviors.

Detection of Audio-Visual Integration Sites in Humans by Application of Electrophysiological Criteria to the BOLD Effect

Electrophysiological studies in nonhuman primates and other mammals have shown that sensory cues from different modalities that appear at the same time and in the same location can increase the firing rate of multisensory cells in the superior colliculus to a level exceeding that predicted by summing the responses to the unimodal inputs. In contrast, spatially disparate multisensory cues can induce a profound response depression. We have previously demonstrated using functional magnetic resonance imaging (fMRI) that similar indices of crossmodal facilitation and inhibition are detectable in human cortex when subjects listen to speech while viewing visually congruent and incongruent lip and mouth movements. Here, we have used fMRI to investigate whether similar BOLD signal changes are observable during the crossmodal integration of nonspeech auditory and visual stimuli, matched or mismatched solely on the basis of their temporal synchrony, and if so, whether these crossmodal effects occur in similar brain areas as those identified during the integration of audio-visual speech. Subjects were exposed to synchronous and asynchronous auditory (white noise bursts) and visual (B/W alternating checkerboard) stimuli and to each modality in isolation. Synchronous and asynchronous bimodal inputs produced superadditive BOLD response enhancement and response depression across a large network of polysensory areas. The most highly significant of these crossmodal gains and decrements were observed in the superior colliculi. Other regions exhibiting these crossmodal interactions included cortex within the superior temporal sulcus, intraparietal sulcus, insula, and several foci in the frontal lobe, including within the superior and ventromedial frontal gyri. These data demonstrate the efficacy of using an analytic approach informed by electrophysiology to identify multisensory integration sites in humans and suggest that the particular network of brain areas implicated in these crossmodal integrative processes are dependent on the nature of the correspondence between the different sensory inputs (e.g. space, time, and/or form).

Evidence from functional magnetic resonance imaging of crossmodal binding in the human heteromodal cortex

Integrating information from the different senses markedly enhances the detection and identification of external stimuli. Compared with unimodal inputs, semantically and/or spatially congruent multisensory cues speed discrimination and improve reaction times. Discordant inputs have the opposite effect, reducing performance and slowing responses. These behavioural features of crossmodal processing appear to have parallels in the response properties of multisensory cells in the superior colliculi and cerebral cortex of non-human mammals. Although spatially concordant multisensory inputs can produce a dramatic, often multiplicative, increase in cellular activity, spatially disparate cues tend to induce a profound response depression. Using functional magnetic resonance imaging (fMRI), we investigated whether similar indices of crossmodal integration are detectable in human cerebral cortex, and for the synthesis of complex inputs relating to stimulus identity. Ten human subjects were exposed to varying epochs of semantically congruent and incongruent audio-visual speech and to each modality in isolation. Brain activations to matched and mismatched audio-visual inputs were contrasted with the combined response to both unimodal conditions. This strategy identified an area of heteromodal cortex in the left superior temporal sulcus that exhibited significant supra-additive response enhancement to matched audio-visual inputs and a corresponding sub-additive response to mismatched inputs. The data provide fMRI evidence of crossmodal binding by convergence in the human heteromodal cortex. They further suggest that response enhancement and depression may be a general property of multisensory integration operating at different levels of the neuroaxis and irrespective of the purpose for which sensory inputs are combined.

How Optimal Depth Cue Integration Depends on the Task

Bayesian parameter estimation can be used to generate statistically optimal solutions to the problem of cue integration. However, the complexity and dimensionality of these solutions is frequently prohibitive. In this paper, we show how the complexity and performance characteristics of the optimal estimator for a task depend strongly on the detailed formulation of the task, including the choice of representation for the scene variables. In particular, some representations lead to simpler inference algorithms than others. We illustrate the problem of cue integration for the perception of depth from two highly disparate cues, cast shadow position and image size, and show how the complexity and performance of the depth estimators depends on the specific representation (choice) of depth parameter. From the analysis we predict human performance on a simple depth discrimination task from the optimal cue integration in each depth representation. We find that the cue-integration strategy used by human subjects can be described as near-optimal using a particular choice of depth representation.

Unimodal sensory experience interferes with responsiveness to the spatial contiguity of multimodal maternal cues in bobwhite quail chicks

This study manipulated the relationship between maternal auditory and visual stimulation to examine how bobwhite quail chick's postnatal sensory experience influences the emergence of early intersensory integration. Results revealed that chicks reared with temporally integrated, temporally sequential, or temporally separated maternal audio-visual cues subsequently preferred spatially congruent maternal auditory and visual cues over spatially disparate maternal cues, suggesting that the temporal relationship of maternal multimodal stimulation is not critical to chicks' emerging sensitivity to spatial contiguity. In contrast, chicks reared with unimodal maternal auditory cues or maternal visual cues following hatching did not prefer spatially congruent maternal auditory and visual cues over spatially disparate maternal stimulation. These results indicate that bobwhite chicks require postnatal exposure to multimodal (auditory and visual) stimulation to exhibit species-typical responsiveness to the spatial colocation of multimodal maternal stimuli. Experience with unimodal maternal stimulation (only auditory or visual) was not sufficent to foster chicks' sensitivity to spatial colocation in the days following hatching. Developmental processes involving both auditory and visual experience appear to underlie the emergence of early intersensory integration.

Cortical computation of stereo disparity.

Our ability to see the world in depth is a major accomplishment of the brain. Previous models of how positionally disparate cues to the two eyes are binocularly matched limit possible matches by invoking uniqueness and continuity constraints. These approaches cannot explain data wherein uniqueness fails and changes in contrast alter depth percepts, or where surface discontinuities cause surfaces to be seen in depth, although they are registered by only one eye (da Vinci stereopsis). A new stereopsis model explains these depth percepts by proposing how cortical complex cells binocularly filter their inputs and how monocular and binocular complex cells compete to determine the winning depth signals.