Contextual and serial discriminations: a new learning paradigm to assess simultaneously the effects of acute stress on retrieval of flexible or stable information in mice

The present study was aimed at simultaneously determining on the same subject, the effects of stress on retrieval of flexible (contextual or temporal) or stable (spatial) information. Three behavioral paradigms carried out in a four-hole board were designed as follows: (1) Simple Discrimination (SD), in which mice learned a single discrimination; (2) Contextual and Serial Discriminations (CSD), in which mice learned two successive discriminations on two different internal contexts; (3) Spatial Serial Discriminations (SSD), in which mice learned two successive discriminations on an identical internal context. The stressor (three inescapable electric footshocks) was delivered 5 min before retention, occurring 5 min or 24 h after acquisition. Results showed that this stressor increased plasmatic corticosterone levels and fear reactivity in an elevated-plus-maze, as compared with nonstressed mice. The stressor reversed the normal pattern of retrieval observed in nonstressed controls in the CSD task, this effect being context dependent, as it was not observed in the SSD task. Overall, our study shows that stress affected the retrieval of flexible and old information, but spared the retrieval of stable or recent ones. Therefore, these behavioral paradigms allow us to study simultaneously, on the same animal, the effects of stress on distinct forms of memory retrieval.     

Phoneme perception in a neonate with a left sylvian infarct

We report the case of a neonate tested three weeks after a neonatal left sylvian infarct. We studied her perception of speech and non-speech stimuli with high-density event-related potentials. The results show that she was able to discriminate not only a change of timbre in tones but also a vowel change, and even a place of articulation contrast in stop consonants. Moreover, a discrimination response to stop consonants was observed even when syllables were produced by different speakers. Her intact right hemisphere was thus able to extract relevant phonetic information in spite of irrelevant acoustic variation. These results suggest that both hemispheres contribute to phoneme perception during the first months of life and confirm our previous findings concerning bilateral responses in normal infants.     

Is Dutch native English? Linguistic analysis by 2-month-olds

A variant of the non-nutritive habituation/dishabituation sucking method was used to test 2-month-old English infants’ perception of languages. This method tests for the spontaneous interest of the baby to a change in the stimulus. English and Japanese were clearly discriminated. The difference between French and Japanese was equally clearly not of interest to babies using this procedure, the babies behaving as though both languages were classified simply as ‘foreign’. In order to further specify babies’ representation of native and foreign language, we used Dutch, which shares a number of suprasegmental features with English. The results from our last 2 experiments indicate that a portion of our 6–12 week-old babies consider Dutch as native, suggesting that we tapped in a transition period where the babies are still refining the suprasegmental specification of their native language.     

Toward a Renewed Theological Culture: Introduction

This article introduces a series of articles analysing the current state of theology and inquiring about the possibilities of a renewed theological culture (not least within secular societies). It places theology, and more precisely, the conditions of a possible renewal thereof, in several fields of tension. Paradigmatic for secular societies is the tension between theology and the natural sciences. It is argued that theology and the natural sciences cultivate different modes of reasoning on different epistemic levels and that no competition between them has to be construed if one is not caught up in the premises of secularism. A brief summary of each of the contributions follows these initial remarks.     

Multisensory spatial representations in eye-centered coordinates for reaching

Humans can reach for objects with their hands whether the objects are seen, heard or touched. Thus, the position of objects is recoded in a joint-centered frame of reference regardless of the sensory modality involved. Our study indicates that this frame of reference is not the only one shared across sensory modalities. The location of reaching targets is also encoded in eye-centered coordinates, whether the targets are visual, auditory, proprioceptive or imaginary. Furthermore, the remembered eye-centered location is updated after each eye and head movement. This is quite surprising since, in principle, a reaching motor command can be computed from any non-visual modality without ever recovering the eye-centered location of the stimulus. This finding may reflect the predominant role of vision in human spatial perception.     

ERPs associated with visual duration discriminations in prefrontal and parietal cortex

An event-related potentials (ERP) study was undertaken to examine the role of prefrontal and parietal association cortices on selective attention and short-term memory functions in a duration discrimination task. Subjects performed better when discriminating the first stimulus relative to the second and not the reverse. Two contingent negative variations (CNV) were obtained for each stimulus duration at prefrontal regions, as well as two P300s at parietal regions. The CNV(S1) component recorded during the first stimulus (S1) appeared to be involved in selective attention at bilateral sites, while the P300(S1) component in the left hemisphere may be implicated in retaining it. The CNV(S2) wave, displayed during the second stimulus (S2), at bilateral sites and the right-sided P300(S2) wave seem to be implicated in working memory. The results indicate that recorded activity at prefrontal and parietal association cortices is tightly linked to task parameters and behavioral performances.     

The contribution of private and public information in foraging by Australasian gannets

Predators that forage on foods with temporally and spatially patchy distributions may rely on private or public sources of information to enhance their chances of foraging success. Using GPS tracking, field observations, and videography, we examined potential sites and mechanisms of information acquisition in departures for foraging trips by colonially breeding Australasian gannets (Morus serrator). Analyses of the bill-fencing ceremony between mated pairs of breeding gannets did not detect correlations between parameters of this reciprocal behavior and foraging trips, as would have been predicted if gannets used this behavior as a source of private information. Instead, 60 % of the departing birds flew directly to join water rafts of other conspecific en route to the feeding grounds. The departure of solitary birds from the water rafts was synchronized (within 60 s) with the arrival of incoming foragers and also among departing birds. Furthermore, solitary departing birds from the rafts left in the same directional quadrant (90º slices) as the prior arriving (67 %) and also prior departing forager (79 %). When associated plunge dives of conspecific were visible from the colony, providing a public source of information, gannets more often departed from the water rafts in groups. Our study thus provides evidence for the use of water rafts, but not the nest site, as locations of information transfer, and also confirms the use of local enhancement as a strategy for foraging flights by Australasian gannets.     

The Leuven Perceptual Organization Screening Test (L-POST), an online test to assess mid-level visual perception

Neuropsychological diagnostic tests of visual perception mostly assess high-level processes like object recognition. Object recognition, however, relies on distinct mid-level processes of perceptual organization that are only implicitly tested in classical tests. The Leuven Perceptual Organization Screening Test (L-POST) fills a gap with respect to clinically oriented tests of mid-level visual function. In 15 online subtests, a range of mid-level processes are covered, such as figure–ground segmentation, local and global processing, and shape perception. We also test the sensitivity to a wide variety of perceptual grouping cues, like common fate, collinearity, proximity, and closure. To reduce cognitive load, a matching-to-sample task is used for all subtests. Our online test can be administered in 20–45 min and is freely available at www.gestaltrevision.be/tests. The online implementation enables us to offer a separate interface for researchers and clinicians to have immediate access to the raw and summary results for each patient and to keep a record of their patient’s entire data. Also, each patient’s results can be flexibly compared with a range of age-matched norm samples. In conclusion, the L-POST is a valuable screening test for perceptual organization. The test allows clinicians to screen for deficits in visual perception and enables researchers to get a broader overview of mid-level visual processes that are preserved or disrupted in a given patient.     

An enhanced experimental procedure to rationalize on the impairment of perception of action capabilities

It is well documented that changes in the physiological states of the perceiver–actor influence the perception of action capabilities. However, because experimental procedures of most studies involved a limitless availability for stimuli visual encoding and perceptual strategies, it remains difficult to adopt a single position among the large range of alternative interpretations for impaired perception. A reaching-to-grasp paradigm under breathing restriction was adapted from Graydon et al. (Cogn Emot 26:1301–1305, 2012) to standardize the time for encoding of stimuli information and narrowed the involvement of perceptual strategies. In the present study, we propose a highly controlled environment where the discrete information is presented during 300 ms, congruently with neurophysiological studies focused on visuomotor transformation. An underestimation of the perception of action capabilities is found under breath restriction, suggesting that 300 ms for stimuli encoding is sufficient to induce altered visuomotor brain transformations when limiting the involvement of perceptual strategies. This result suggests that such behavior could refer to an impaired brain potentiation of the perceptual occurrence, providing strong hypotheses on the brain dynamics of sensorimotor integration that underlie impaired perception of action capabilities in stressful situations.     

Preschoolers use phrasal prosody online to constrain syntactic analysis

Two experiments were conducted to investigate whether young children are able to take into account phrasal prosody when computing the syntactic structure of a sentence. Pairs of French noun/verb homophones were selected to create locally ambiguous sentences ([la petite ferme ] [est très jolie] ‘the small farm is very nice’ vs. [la petite] [ ferme la fenêtre] ‘the little girl closes the window’ – brackets indicate prosodic boundaries). Although these sentences start with the same three words, ferme is a noun (farm) in the former but a verb (to close) in the latter case. The only difference between these sentence beginnings is the prosodic structure, that reflects the syntactic structure (with a prosodic boundary just before the critical word when it is a verb, and just after it when it is a noun). Crucially, all words following the homophone were masked, such that prosodic cues were the only disambiguating information. Children successfully exploited prosodic information to assign the appropriate syntactic category to the target word, in both an oral completion task (4.5‐year‐olds, Experiment 1) and in a preferential looking paradigm with an eye‐tracker (3.5‐year‐olds and 4.5‐year‐olds, Experiment 2). These results show that both groups of children exploit the position of a word within the prosodic structure when computing its syntactic category. In other words, even younger children of 3.5 years old exploit phrasal prosody online to constrain their syntactic analysis. This ability to exploit phrasal prosody to compute syntactic structure may help children parse sentences containing unknown words, and facilitate the acquisition of word meanings.