A developmental study of timing behavior in 4 1/2- and 7-year-old children

The present study investigated effects of age and instructions on temporal regulations of behavior in children. In the first experiment 4 1/2-year-old and 7-year-old subjects were trained with a DRL (differential reinforcement of low rates) 5-s and a DRL 10-s schedule. Results demonstrate that age and timing performance are related. Seven-year-olds are more efficient than the 4 1/2-year-olds. A striking decline in the 4 1/2-year-old children's capacity to space responses was observed in the DRL 10-s schedule as compared to the DRL 5-s schedule. Analysis of individual performances suggests that the evolution of DRL performance between 4 and 7 years of age depends not only on the development of the capacity to delay responding but also on the acquisition of the ability to represent the reinforcement contingencies, that is, the temporal parameters of the task to oneself. In order to test this hypothesis a second experiment was conducted where instructions to wait between operant responses were given to a group of 4 1/2-year-old subjects at the beginning of a DRL 5-s and a DRL 10-s schedule. The results show that these instructions enhance DRL performance. By directing the 4 1/2-year-old subjects' attention to the temporal requirements of the task, instructions led to efficient performance and accurate timing of responses to the DRL schedule.     

Angiotensin-(1-7)/Mas axis integrity is required for the expression of object recognition memory

It has been shown that the brain has its own intrinsic renin-angiotensin system (RAS) and angiotensin-(1-7) (Ang-(1-7)) is particularly interesting, because it appears to counterbalance most of the Ang II effects. Ang-(1-7) exerts its biological function through activation of the G-protein-coupled receptor Mas. Interestingly, hippocampus is one of the regions with higher expression of Mas. However, the role of Ang-(1-7)/Mas axis in hippocampus-dependent memories is still poorly understood. Here we demonstrated that Mas ablation, as well as the blockade of Mas in the CA1-hippocampus, impaired object recognition memory (ORM). We also demonstrated that the blockade of Ang II receptors AT1, but not AT2, recovers ORM impairment of Mas-deficient mice. Considering that high concentrations of Ang-(1-7) may activate AT1 receptors, nonspecifically, we evaluate the levels of Ang-(1-7) and its main precursors Ang I and Ang II in the hippocampus of Mas-deficient mice. The Ang I and Ang II levels are unaltered in the whole hipocampus of MasKo. However, Ang-(1-7) concentration is increased in the whole hippocampus of MasKo mice, as well as in the CA1 area. Taken together, our findings suggest that the functionality of the Ang-(1-7)/Mas axis is essential for normal ORM processing.     

Anticipation of subsequent demanding exercise increases the expression of haem oxygenase-1 mRNA in human lymphocytes

Oxidative stress induces the expression of the cytoprotective and anti-inflammatory protein haem oxygenase-1 (HO-1). In the present investigation, we show that anticipation of subsequent exercise elevates the expression of HO-1 mRNA in lymphocytes. A between-groups comparison of HO-1 mRNA expression in subjects about to complete a half marathon race vs. subjects who were asked to sit quietly in the laboratory showed an elevated expression of HO-1 mRNA prior to exercise (2.6-fold higher in subjects prior to the half marathon, P < 0.01). This observation led us to examine whether anticipation of subsequent exercise leads to differences in lymphocyte HO-1 mRNA expression within the same subjects. In a second experiment, the same individuals completed two trials, one exercise and one rest, approximately 2 weeks apart in a randomised cross-over design. Lymphocyte HO-1 mRNA expression was greater prior to exercise (1.4 +/- 0.3-fold higher in the exercise trial, P < 0.05). These results suggest that knowledge of subsequent demanding exercise may lead to an anticipatory induction of HO-1 mRNA. We tentatively propose that this process has evolved to prepare lymphocytes for subsequent exercise-induced oxidative stress although the mechanism remains to be elucidated.     

Angiotensin-(1-7)-induced plasticity changes in the lateral amygdala are mediated by COX-2 and NO

It is known from studies outside the brain that upon binding to its receptor, angiotensin-(1-7) elicits the release of prostanoids and nitric oxide (NO). Cyclooxygenase (COX) is a key enzyme that converts arachidonic acid to prostaglandins. Since there are no data available so far on the role of COX-2 in the amygdala, in a first step we demonstrated that the selective COX-2 inhibitor NS-398 significantly reduced the probability of long-term potentiation (LTP) induction in the lateral nucleus of the amygdala. Similarly, in COX-2^−/− mice, LTP induced by external capsule (EC) stimulation was impaired. Second, we evaluated the action of angiotensin-(1-7) in the amygdala. In wild-type mice, angiotensin-(1-7) increased LTP. This LTP-enhancing effect of Ang-(1-7) was not observed in COX-2^+/− mice. However, in COX-2^−/− mice, Ang-(1-7) caused an enhancement of LTP similar to that in wild-type mice. The NO synthetase inhibitor L-NAME blocked this angiotensin-(1-7)-induced increase in LTP in COX-2^−/− mice. Low-frequency stimulation of external capsule fibers did not cause long-term depression (LTD) in drug-free and angiotensin-(1-7)-treated brain slices in wild-type mice. In contrast, in COX-2^−/− mice, angiotensin-(1-7) caused stable LTD. Increasing NO concentration by the NO-donor SNAP also caused LTD in wild-type mice. Our study shows for the first time that LTP in the amygdala is dependent on COX-2 activity. Moreover, COX-2 is involved in the mediation of angiotensin-(1-7) effects on LTP. Finally, it is recognized that there is a molecular cross-talk between COX-2 and NO that may regulate synaptic plasticity.     

Differential effects of articulatory suppression on cue-switch and task-switch trials in random task cueing with 2:1 mapping

Recent studies have revealed that verbal representations play an important role in various task-switching situations. This study examined whether verbal representations contribute to the actual switching process using random task cueing with two cues per task. This procedure allowed us to produce a trial in which the cue switched, but the task repeated, thereby separating the cue-switching process from the actual task-switching process. Participants performed colour or shape judgements that were initiated by an arbitrary symbol cue (Experiments 1 and 2) or a kanji cue (Experiment 3) under control, articulatory-suppression, and foot-tapping conditions. In Experiments 1 and 2 with the arbitrary cues, articulatory suppression impaired performance in only the cue-switch condition. In Experiment 3, in which a kanji cue indicated the upcoming task name, articulatory suppression did not have any effects. These results suggest that the involvement of verbal representations in random task cueing is based on the cue-switching process rather than on the task-switching process.     

Differential effects of articulatory suppression on cue-switch and task-switch trials in random task cueing with 2:1 mapping

Recent studies have revealed that verbal representations play an important role in various task-switching situations. This study examined whether verbal representations contribute to the actual switching process using random task cueing with two cues per task. This procedure allowed us to produce a trial in which the cue switched, but the task repeated, thereby separating the cue-switching process from the actual task-switching process. Participants performed colour or shape judgements that were initiated by an arbitrary symbol cue (Experiments 1 and 2) or a kanji cue (Experiment 3) under control, articulatory-suppression, and foot-tapping conditions. In Experiments 1 and 2 with the arbitrary cues, articulatory suppression impaired performance in only the cue-switch condition. In Experiment 3, in which a kanji cue indicated the upcoming task name, articulatory suppression did not have any effects. These results suggest that the involvement of verbal representations in random task cueing is based on the cue-switching process rather than on the task-switching process.     

Different involvement of type 1, 2, and 3 ryanodine receptors in memory processes

The administration of the ryanodine receptor (RyR) agonist 4-Cmc (0.003-9 nmol per mouse intracerebroventricularly [i.c.v.]) ameliorated memory functions, whereas the RyR antagonist ryanodine (0.0001-1 nmol per mouse i.c.v.) induced amnesia in the mouse passive avoidance test. The role of the type 1, 2, and 3 RyR isoforms in memory processes was then evaluated by inhibiting the expression of the three RyR proteins in the mouse brain. A selective knockdown of the RyR isoforms was obtained by the i.c.v. administration of antisense oligonucleotides (aODNs) complementary to the sequence of RyR1, RyR2 and RyR3 proteins, as demonstrated by immunoblotting experiments. RyR1 (5-9 nmol per mouse i.c.v.) knockdown mice did not show any memory dysfunction. Conversely, RyR2 (1-7 nmol per mouse i.c.v.) and RyR3 (1-7 nmol per mouse i.c.v.) knockdown animals showed an impairment of memory processes. This detrimental effect was temporary and reversible, disappearing 7 d after the end of the aODN treatment. At the highest effective doses, none of the compounds used impaired motor coordination, as revealed by the rota rod test, nor modified spontaneous mobility and inspection activity, as revealed by the hole-board test. In conclusion, the lack of any involvement of cerebral RyR1 was demonstrated. These findings also showed the involvement of type 2 and type 3 RyR in the modulation of memory functions identifying these cerebral RyR isoforms as critical targets underlying memory processes.     

Diurnal expression of period 2 and urocortin 1 in neurones of the non-preganglionic Edinger-Westphal nucleus in the rat

Period 2 (Per2) is an important clock gene involved in the regulation of the major circadian clock in the mammalian central nervous system, the suprachiasmatic nucleus. In addition, Per2 is expressed in many other stress-sensitive brain structures. We have previously showed that the non-preganglionic Edinger-Westphal nucleus (npEW) is the main site of the corticotropin-releasing factor peptide family member urocortin 1 (Ucn1) and that this peptide undergoes conspicuous expression changes in response to various stressors. Here, we hypothesized that in the rat npEW both Per2 and Ucn1 would be produced in a diurnal, rhythmical fashion. This hypothesis was tested by following this expected rhythm on two days in rats killed at four time points each day (Zeitgeber times 0, 6, 12, and 18). We showed the co-existence of Per2 and Ucn1 in the npEW with double-label immunofluorescence and demonstrated with quantitative RT-PCR and semi-quantitative immunocytochemistry diurnal rhythms in Per2 mRNA expression and Per2 protein content, each on a single different day, with a minimum at lights-off and a maximum at lights-on. We furthermore revealed a diurnal rhythm in the number of Ucn1-immunopositive neurones and in their Ucn1 peptide content, with a minimum at night and at the beginning of the light period and a peak at lights-off, while the Ucn1 mRNA content paralleled the Per2 mRNA rhythm. The rhythms were accompanied by a diurnal rhythm in plasma corticosterone concentration. Our results are in line with the hypothesis that both Per2 and Ucn1 in the rat npEW are produced in a diurnal fashion, a phenomenon that may be relevant for the regulation of the diurnal rhythm in the stress response.     

Patients' versus informants' reports of personality disorders in predicting 7 1/2-year outcome in outpatients with depressive disorders

Concordance between patients' and informants' reports of personality disorders (PDs) is low, raising the questions of which source provides more valid data and whether both contribute unique information. This study compared patients' and informants' reports of PDs in predicting outcome in a 7 1/2-year follow-up of 85 depressed outpatients. Patients and informants were independently evaluated using structured interviews; outcome was assessed using structured interviews with patients. Both patients' and informants' reports of PD diagnoses and dimensional scores independently predicted depression symptoms and global functioning at follow-up. However, only informants' reports made a unique contribution to predicting social adjustment. This finding indicates that both patients and informants provide unique information on Axis II psychopathology and argues for the use of both sources in the assessment of PDs.     

Effect of stimulus pre-exposure on inhibitory avoidance retrieval-associated changes in the phosphorylated form of the extracellular signal-regulated kinase-1 and -2 (pERK1/2)

One goal of the present study was to determine how pre-exposure to a set of contextual cues affected subsequent reinforced inhibitory avoidance task performance using those cues (latent inhibition model). In addition, immunohistochemical assessment of the phosphorylated (activated) form of the extracellular signal-regulated kinase-1 and -2 (pERK1/2) was examined. Adult, male Long Evans rats were randomly assigned into either pre-exposure (PE) or different pre-exposure (DPE) groups. All rats received 3 days of contextual pre-exposure (same or different context as that used for reinforced training) and were trained, 24 h later, on an inhibitory avoidance task (with or without shock). Rats were euthanized 24 h after training; half with a retention test and half without. Behaviorally, the PE group showed reduced latencies to enter the dark/shock compartment during the retention test compared to the DPE group showing the latent inhibition phenomenon. Compared to the shocked and tested DPE group, the shocked and tested PE group showed fewer pERK1/2-ir neurons in the secondary motor cortex, the anterior cingulate, the pre- and infra-limbic cortices, and the central nucleus of the amygdala. These regions showed similar numbers of pERK1/2-labeled neurons when comparing the shocked and tested PE group with the nonshocked and tested PE group. This suggests the possibility that brain regions showing decreased pERK1/2 levels in association with attenuated inhibitory avoidance performance may be involved in different aspects of the memory retrieval process.     

Roles of dopamine D1 and D2 receptors in the acquisition and expression of fat-conditioned flavor preferences in rats

Sugars and fats elicit innate and learned flavor preferences with the latter mediated by flavor-flavor (orosensory) and flavor-nutrient (post-ingestive) processes. Systemic dopamine (DA) D1 (SCH23390: SCH) and D2 (raclopride: RAC), but not opioid antagonists blocked the acquisition and expression of flavor-flavor preferences conditioned by sugars. In addition, systemic D1, but not D2 or opioid antagonists blocked the acquisition of flavor-nutrient preferences conditioned by intragastric (IG) sugar infusions. Given that DA antagonists reduce fat intake, the present study examined whether systemic D1 or D2 antagonists altered the acquisition and/or expression of conditioned flavor preferences (CFP) produced by pairing one novel flavor (CS+, e.g., cherry) with a 3.5% corn oil (CO: fat) solution relative to another flavor (CS-, e.g., grape) paired with a 0.9% CO solution. In an expression study, food-restricted rats were trained to drink either flavored 3.5% or 0.9% CO solutions on alternate days. Subsequent two-bottle tests with the CS+ and CS- flavors mixed in 0.9% CO solutions occurred 0.5h after systemic administration of vehicle (VEH), SCH (50-800 nmol/kg) or RAC (50-800 nmol/kg). The rats displayed a robust CS+ preference following VEH treatment (87-88%) the expression of which was attenuated by treatment with moderate doses of RAC, and to a lesser degree, SCH. In an acquisition study, six groups of rats received VEH, SCH (25, 50, 200 nmol/kg) or RAC (50, 200 nmol/kg) 0.5 h prior to 1-bottle training trials with CS+ flavored 3.5% and CS- flavored 0.9% (CS-) CO solutions. A seventh Limited VEH group was trained with its training intakes limited to that of the SCH and RAC groups. Subsequent two-bottle tests were conducted with the CS+ and CS- flavors presented in 0.9% CO without injections. Significant and persistent CS+ preferences were observed in VEH (75-82%), Limited VEH (70-88%), SCH25 (75-84%), SCH50 (64-87%), SCH200 (78-91%) and RAC200 (74-91%) groups. In contrast, the group trained with RAC50 displayed a significant initial CS+ preference (76%) which declined over testing to 61%. These data indicate limited DA D1 and D2 receptor signaling involvement in the expression and acquisition of a fat-CFP relative to previous robust effects for sugar-CFP.     

A gestural repertoire of 1- to 2-year-old human children: in search of the ape gestures

Animal Cognition - When we compare human gestures to those of other apes, it looks at first like there is nothing much to compare at all. In adult humans, gestures are thought to be a window into...     

A Developmental Vocabulary Assessment for Parents (DVAP): Validating Parental Report of Vocabulary Size in 2- to 7-Year-Old Children

Measuring individual differences in children's emerging language abilities is important to researchers and clinicians alike. The 2 most widely used methods for assessing children's vocabulary both have limitations: Experimenter-administered tests are time-consuming and expensive, and parent questionnaires have only been designed for children up to 37 months of age. Here, we test the validity of a new assessment to fill this gap: the Developmental Vocabulary Assessment for Parents (DVAP). In 4 experiments, we assess the reliability of this measure and its concurrent and predictive validity in samples of 2- to 7-year-old children. We found that the DVAP provides a rapid, cost-effective alternative to experimenter-administered vocabulary tests for children.     

Perception Abilities of L1 Cypriot Greek Listeners - Types of Errors Involving Plosive Consonants in L2 English

This paper investigates the difficulties adult second language (L2) users of English encounter with plosive consonants in the L2. It presents the results of a task examining the acquisition of plosive voicing contrasts by college students with Cypriot Greek (CG) linguistic background. The task focused on the types of errors involving plosive consonants indicating that performance was significantly better in the voiceless plosive category. Participants were able to perceive voiced plosives but they treated such instances as a /nasal + voiced plosive/ sequence. Therefore, the question raised concerns different phonological contrasts realised through similar phonetic cues. The patterns observed suggested that this gap between phonetic cues and phonological contrast might explain why CG users have difficulties perceiving voiced English plosives. In this context, voice onset time (VOT) differences between the L1 and L2 are of crucial importance. In English, voiced plosives are characterised by short lag VOT while their voiceless counterparts fall within the long lag VOT continuum. The same phonetic contrast is used in CG to differentiate between single and geminate voiceless plosives. The results are discussed in relation to the frameworks of second language phonology and speech perception suggesting that the difficulties faced by the L2 listeners support the operation of a phonetic-phonological challenge.     

Temporal learning in 4 1/2- and 6-year-old children: role of instructions and prior knowledge

The present study investigates effects of different types of instructions (high-rate, interval, and minimal) during training with a fixed-interval schedule as a function of prior acquired temporal knowledge. A pretest was used to assess 4 1/2- and 6-year-old children's ability to understand the temporal parameters of a fixed-interval schedule of reinforcement. The results as a whole show that the control exerted by instructions given by the experimenter or elaborated by the subjects themselves on fixed-interval performance of young children depends on the interaction of two factors: development of verbal self-control skills and mastery of knowledge required by the rules forming the instructions.     

Effects of a no-go Task 2 on Task 1 performance in dual - tasking: From benefits to costs

When two tasks are combined in a dual-task experiment, characteristics of Task 2 can influence Task 1 performance, a phenomenon termed the backward crosstalk effect (BCE). Besides instances depending on the (spatial) compatibility of both responses, a particularly interesting example was introduced by Miller (2006): If Task 2 was a no-go task (i.e., one not requiring any action at all), responses were slowed in Task 1. Subsequent work, however, also reported the opposite result—that is, faster Task 1 responses in cases of no-go Task 2 trials. We report three experiments aiming to more precisely identify the conditions under which a no-go Task 2 facilitates or impedes Task 1 performance. The results suggest that an adverse no-go BCE is only observed when the Task 2 response(s) are sufficiently prepared in advance, yielding strong inhibitory control demands for Task 2 that eventually hamper Task 1 processing as well (i.e., inhibitory costs). If this is not the case, encountering a no-go Task 2 trial facilitates Task 1 performance, suggesting that the underlying task representation is reduced to a single - task. These results are discussed in the context of other recent work on BCEs and of recently suggested accounts of the no-go BCE.