Anxiogenic-like effects of gamma-hydroxybutyric acid (GHB) in mice tested in the light-dark box

Gamma-hydroxybutyric acid (GHB) is a drug with abuse potential, popularly known as "liquid ecstasy". It is an endogenous compound of the mammalian brain which satisfies many of the criteria for consideration as a neurotransmitter or neuromodulator. In this study, the effects of acute administration of GHB (40, 80 and 120 mg/kg, ip) on anxiety, tested in the light/dark box, were examined in male mice of the OF.1 strain. Likewise, we compared the behavioural profile of GHB with that induced by mCPP (1 mg/kg, ip), a compound with known anxiogenic actions. GHB-treated mice spent notably less time in the lit area (40 and 80 mg/kg) and more time in the dark area (all doses), whereas the total number of 'rearings', transitions and latency were significantly reduced. A very similar behavioural profile was observed in mCPP-treated animals. Overall, these findings indicate that GHB exhibits anxiogenic-like properties in male mice. It is suggested that the anxiogenic effects of GHB could be related to its ability to modulate GABA and/or dopaminergic receptors.     

Role of TRPV1 in consolidation of fear memories depends on the averseness of the conditioning procedure

Despite the fact that TRPV1 receptors are widely expressed in brain structures such as the hippocampus, its functions remain largely unknown. In the present study, we have investigated the possible modulatory role of the hippocampal endovanilloid system upon memory consolidation of two different behavioral tasks in rats. Post-training infusion of the TRPV1 antagonist capsazepine disrupted memory consolidation with a strong training protocol, but not with a weak one in the contextual fear conditioning or in the step-down inhibitory avoidance task. These results provide evidence that the modulation of the hippocampal memory consolidation through TRPV1 receptors takes place only in presence of a strong emotional experience, suggesting that a certain aversiveness level is required in order to recruit endovanilloids to exert this function. A possible synergic role of hippocampal endovanilloid and endocannabinoid system on memory consolidation is discussed.     

Homing in rocky intertidal fish. Are Lipophrys pholis L. able to perform true navigation?

Although navigation is common in many animals, only a few perform true navigation, meaning that they have the ability to return to a given place by relying on indirect cues obtained at the release site (i.e., by relying on information from a “map and compass” mechanism). The common intertidal fish, Lipophrys pholis, is thought to have homing abilities through a mechanism that primarily makes use of familiar landmarks (i.e., piloting). Anecdotal reports that individuals return to their home pools after release at unfamiliar sites suggest that L. pholis might use cues collected at the release site to find their way back (i.e., they might use map and compass information). Using a completely artificial setup, we tested the homing abilities of L. pholis as a function of age, sex, and familiarity with the release site. The findings showed that motivation for homing is present only in the adult phase and is independent of sex and/or familiarity with the release site. Moreover, adults released at a completely unfamiliar place oriented themselves in a direction roughly similar to that of their home pools. The fact that L. pholis were tested in a complete artificial environment means that hydrodynamic cues can be excluded as playing a role in this process and restricts the candidate options (e.g., magnetic cues). The ability to perform navigation based on a “map and compass” mechanism raises many interesting questions about the learning process, once these individuals have restricted home ranges during their lives. In vertebrate navigation, the cues used during the navigation process are a question of debate, and L. pholis offers an outstanding model to test hypotheses and ultimately provide answers.     

Implicit learning shapes new conscious percepts and representations

We present here the lineaments of a new account of implicit learning, an account that does not rely on the notion of “implicit knowledge.” In this account, improved performance depends on the action of unconscious mechanisms that structure the phenomenal, conscious experience of the world. This integrative view makes groundless the search for dissociations between conscious and unconscious influences that has been at the core of the research on implicit learning and memory. We contrast this view, on the one hand, to Dienes and Berry’s (1997) proposal, which defines implicit learning by analogy with subliminal perception, and, on the other, to Neal and Hesketh’s (1997) episodic account, in which subjective experience is a starting point for inquiry, rather than the phenomenon requiring explanation.     

Behavioural problems in adolescents who are in adoption, residential care, and grandparent fostering

The aim of this research is to identify the severity and type of behavioural problems found in a sample of 181 Spanish adolescents, aged 11 and 18, who have been, or still are in the protective system and to provide give up-to-date figures about behavioural problem situations of children are living under protective measures, and to determine the existence of diverse behavioural problems concerning the kind of care the adolescents are receiving (adoption, residential care, or with grandparent fostering). The Child Behavior Checklist (CBCL) was used in this study. The results show that most of the adolescents scored within the normal range and only a small percentage of them had important behavioural problems and were therefore situated within the clinical range of the trial. The adopted adolescents scored higher than the adolescents who were either fostered by their extended families or in residential care. The main problems identified in each section are discussed, along with the results, in the context of modernising the Spanish protection system.     

Exposure to novelty enhances retrieval of very remote memory in rats

Rats were trained in a one-trial step-down inhibitory avoidance task at the age of 3 months and tested for retention 1 day later, or 3, 6, 9, 12, 15, and 19 months later, i.e., when the animals were 3, 6, 9, 12, 15, 18, or 22 months of age. Retrieval performance declined with time and was undetectable in the last two age groups. Exposure to an unrelated novel environment (a square box lined with black plastic) 1 h before retention testing enhanced retrieval at all ages, regardless of the decline in the level of test session performance. The effect cannot be explained by an anxiogenic effect of the novelty box, or by an influence of novelty on locomotion or exploration, or by a nonspecific influence of exposure to novelty on step-down latency in the inhibitory avoidance apparatus.     

The formation of structurally relevant units in artificial grammar learning

A total of 78 adult participants were asked to read a sample of strings generated by a finite state grammar and, immediately after reading each string, to mark the natural segmentation positions with a slash bar. They repeated the same task after a phase of familiarization with the material, which consisted, depending on the group involved, of learning items by rote, performing a shortterm matching task, or searching for the rules of the grammar. Participants formed the same number of cognitive units before and after the training phase, thus indicating that they did not tend to form increasingly large units. However, the number of different units reliably decreased, whatever the task that participants had performed during familiarization. This result indicates that segmentation was increasingly consistent with the structure of the grammar. A theoretical account of this phenomenon, based on ubiquitous principles of associative memory and learning, is proposed. This account is supported by the ability of a computer model implementing those principles, PARSER, to reproduce the observed pattern of results. The implications of this study for developmental theories aimed at accounting for how children become able to parse sensory input into physically and linguistically relevant units are discussed.