Effect of phonological training in French children with SLI: Perspectives on voicing identification, discrimination and categorical perception

The aim of the present study was to investigate the effect of auditory training on voicing perception in French children with specific language impairment (SLI). We used an adaptive discrimination training that was centred across the French phonological boundary (0ms voice onset time - VOT). One group of nine children with SLI attended eighteen twenty-minute training sessions with feedback, and a control group of nine children with SLI did not receive any training. Identification, discrimination and categorical perception were evaluated before, during and after training as well as one month following the final session. Phonological awareness and vocabulary were also assessed for both groups. The results showed that children with SLI experienced strong difficulties in the identification, discrimination and categorical perception of the voicing continuum prior to training. However, as early as after the first nine training sessions, their performance in the identification and discrimination tasks increased significantly. Moreover, phonological awareness scores improved during training, whereas vocabulary scores remained stable across sessions.     

Grammar predicts procedural learning and consolidation deficits in children with Specific Language Impairment

The Procedural Deficit Hypothesis (PDH) posits that Specific Language Impairment (SLI) can be largely explained by abnormalities of brain structures that subserve procedural memory. The PDH predicts impairments of procedural memory itself, and that such impairments underlie the grammatical deficits observed in the disorder. Previous studies have indeed reported procedural learning impairments in SLI, and have found that these are associated with grammatical difficulties. The present study extends this research by examining consolidation and longer-term procedural sequence learning in children with SLI. The Alternating Serial Reaction Time (ASRT) task was given to children with SLI and typically developing (TD) children in an initial learning session and an average of three days later to test for consolidation and longer-term learning. Although both groups showed evidence of initial sequence learning, only the TD children showed clear signs of consolidation, even though the two groups did not differ in longer-term learning. When the children were re-categorized on the basis of grammar deficits rather than broader language deficits, a clearer pattern emerged. Whereas both the grammar impaired and normal grammar groups showed evidence of initial sequence learning, only those with normal grammar showed consolidation and longer-term learning. Indeed, the grammar-impaired group appeared to lose any sequence knowledge gained during the initial testing session. These findings held even when controlling for vocabulary or a broad non-grammatical language measure, neither of which were associated with procedural memory. When grammar was examined as a continuous variable over all children, the same relationships between procedural memory and grammar, but not vocabulary or the broader language measure, were observed. Overall, the findings support and further specify the PDH. They suggest that consolidation and longer-term procedural learning are impaired in SLI, but that these impairments are specifically tied to the grammatical deficits in the disorder. The possibility that consolidation and longer-term learning are problematic in the disorder suggests a locus of potential study for therapeutic approaches. In sum, this study clarifies our understanding of the underlying deficits in SLI, and suggests avenues for further research.     

Atypical acquisition and atypical expression of memory consolidation gains in a motor skill in young female adults with ADHD

Individuals with ADHD often show performance deficits in motor tasks. It is not clear, however, whether this reflects less effective acquisition of skill (procedural knowledge), or deficient consolidation into long-term memory, in ADHD. The aim of the study was to compare the acquisition of skilled motor performance, the expression of delayed - consolidation phase - gains and retention, in persons with and without ADHD. Thirty-two participants, 16 with ADHD, were trained on a sequence of finger movements using a well-established training protocol, and tested before training and immediately, 24 h and 2 weeks after training. Both groups showed similar within-session gains in speed; additional, delayed gains were expressed at 24 h, but less robustly in ADHD, and at 2 weeks post-training. However, while controls showed significant delayed gains in accuracy at 24 h and 2 weeks post-training, accuracy deteriorated in ADHD from pre-training to 24 h post-training and was only at pre-training levels by 2-weeks post-training. Our results demonstrate a latent memory consolidation phase in motor sequence learning, expressed as delayed gains in speed and a much delayed recovery of pre-training accuracy, in individuals with ADHD. However, both the acquisition and memory consolidation of motor skills are atypical in ADHD.     

Serial order short-term memory capacities and specific language impairment: No evidence for a causal association

This study re-explored the nature of verbal short-term memory (STM) deficits in children with specific language impairment (SLI), by distinguishing item and serial order STM processes. Recent studies have shown serial order STM capacity to be a critical determinant of language development, relative to item STM. In Experiment 1, 12 children with SLI, 12 age-matched children and 12 language-matched children were administered serial order recognition and reconstruction tasks. Experiment 2 assessed implicit serial learning abilities via a Hebb learning task. The SLI group showed impaired performance for the serial order reconstruction and recognition tasks, relative to language-matched and/or age-matched control groups. However, normal serial position effects were observed in all SLI children in the serial order reconstruction task, suggesting normal coding of serial position information. Similarly, performance on the Hebb serial learning task was at chronological age appropriate levels. Experiment 3 showed that the group differences observed for the serial order STM tasks in Experiment 1 disappeared when the SLI group was compared to a mental age-matched control group. Experiment 4 showed similar performance levels in the SLI group and the mental age-matched control group for a nonword recognition task assessing item STM capacities. This study shows that children with SLI have no specific impairments for serial order and item STM components but that poorer general cognitive efficiency is related to functional limitations in verbal STM tasks. The data are in line with limited information processing accounts of SLI.     

Improvement of shuttle-box learning with pre- and post-trial intracranial self-stimulation in rats

The effects of intracranial self-stimulation (ICSS) in the lateral hypothalamus upon the acquisition and long-term retention (LTR) of shuttle box avoidance conditioning were studied in Wistar rats. Two groups of subjects learned the avoidance task in 5 daily training sessions and were allowed to self-stimulate either before (Pre-ICSS group), or after (Post-ICSS group) each training session. A control group received training but no ICSS. Ten days following the last training session, LTR of the task was determined in one avoidance session without ICSS. A fourth group was added post-hoc which was allowed to self-stimulate before the training sessions as well as before the LTR test. Both the Post-ICSS and Pre-ICSS groups improved in acquisition of the learned response over the successive training sessions, as compared with Controls. In the LTR test, the animals of the Post-ICSS group maintained the response level achieved in the last acquisition session. In contrast, the subjects of the Pre-ICSS group showed a significant decrease of the same response, unless they were given ICSS treatment prior to the LTR test. This may indicate a 'state-dependent learning' effect being responsible for the decrease in the LTR observed in Pre-ICSS group. Because both pre- and post-training ICSS treatments improved the acquisition and the LTR of the learned response, it is suggested that the contingency of the treatment with training (that is, ICSS treatment immediately after the training sessions) is not a necessary condition to facilitate the acquisition and the consolidation of two-way active avoidance learning.     

Delayed motor skill acquisition in kindergarten children with language impairment

The acquisition and consolidation of a new grapho-motor symbol into long-term memory was studied in 5-year-old children with language impairment (LI) and peers matched for age and visual-motor integration skills. The children practiced the production of a new symbol and were tested 24h and two weeks post-practice day. Differences in performance speed emerged between the groups: children with LI showed a later onset of rapid learning in the practice phase, and only the comparison group exhibited delayed, consolidation, gains 24h post-training. At two weeks post-training, children with LI improved, closing the gap in performance speed. Speed-accuracy trade-off was characteristic of speed improvements in LI. These results indicate atypical and delayed acquisition in children with LI, and support the view that deficient skill acquisition in LI goes beyond the language system.     

Virtual water maze learning in human increases functional connectivity between posterior hippocampus and dorsal caudate

Recent work has demonstrated that functional connectivity between remote brain regions can be modulated by task learning or the performance of an already well‐learned task. Here, we investigated the extent to which initial learning and stable performance of a spatial navigation task modulates functional connectivity between subregions of hippocampus and striatum. Subjects actively navigated through a virtual water maze environment and used visual cues to learn the position of a fixed spatial location. Resting‐state functional magnetic resonance imaging scans were collected before and after virtual water maze navigation in two scan sessions conducted 1 week apart, with a behavior‐only training session in between. There was a large significant reduction in the time taken to intercept the target location during scan session 1 and a small significant reduction during the behavior‐only training session. No further reduction was observed during scan session 2. This indicates that scan session 1 represented initial learning and scan session 2 represented stable performance. We observed an increase in functional connectivity between left posterior hippocampus and left dorsal caudate that was specific to scan session 1. Importantly, the magnitude of the increase in functional connectivity was correlated with offline gains in task performance. Our findings suggest cooperative interaction occurs between posterior hippocampus and dorsal caudate during awake rest following the initial phase of spatial navigation learning. Furthermore, we speculate that the increase in functional connectivity observed during awake rest after initial learning might reflect consolidation‐related processing. Hum Brain Mapp 36:1265–1277, 2015. © 2014 Wiley Periodicals, Inc.     

Posttraining transcranial magnetic stimulation of striate cortex disrupts consolidation early in visual skill learning

Practice-induced improvements in skilled performance reflect "offline " consolidation processes extending beyond daily training sessions. According to visual learning theories, an early, fast learning phase driven by high-level areas is followed by a late, asymptotic learning phase driven by low-level, retinotopic areas when higher resolution is required. Thus, low-level areas would not contribute to learning and offline consolidation until late learning. Recent studies have challenged this notion, demonstrating modified responses to trained stimuli in primary visual cortex (V1) and offline activity after very limited training. However, the behavioral relevance of modified V1 activity for offline consolidation of visual skill memory in V1 after early training sessions remains unclear. Here, we used neuronavigated transcranial magnetic stimulation (TMS) directed to a trained retinotopic V1 location to test for behaviorally relevant consolidation in human low-level visual cortex. Applying TMS to the trained V1 location within 45 min of the first or second training session strongly interfered with learning, as measured by impaired performance the next day. The interference was conditional on task context and occurred only when training in the location targeted by TMS was followed by training in a second location before TMS. In this condition, high-level areas may become coupled to the second location and uncoupled from the previously trained low-level representation, thereby rendering consolidation vulnerable to interference. Our data show that, during the earliest phases of skill learning in the lowest-level visual areas, a behaviorally relevant form of consolidation exists of which the robustness is controlled by high-level, contextual factors.     

Empirical tests of the functional significance of amygdala-based modulation of hippocampal representations: evidence for multiple memory consolidation pathways

This series of experiments evaluated the effects of amygdala damage on the acquisition and long-term retention of variants of the water task, and tested the hypothesis that the amygdala is an essential neural system for consolidation of hippocampal memories. In Experiment 1, rats with large, neurotoxic lesions of the amygdala (AMYG) showed normal acquisition on the standard spatial version of the water task, as well as normal retention and decay rate profiles on the 24-h and 30-day retention probes. In Experiment 2, AMYG rats showed normal one-trial place learning abilities and could retain this one-trial information over a 24 h delay. Experiment 3 showed that the amygdala lesions used in this study were functionally significant because AMYG rats, from Experiment 2, showed impairments in a discriminative fear conditioning to context paradigm. Experiment 4 was a critical test of the idea that the amygdala is a decisive locus for consolidation of hippocampal memories. AMYG rats were trained to sub-asymptotic levels of performance on the standard version of the water task. Following each training session, the subjects were given a post-training peripheral injection of D-amphetamine. A probe test revealed that normal subjects and AMYG rats showed similar post-training memory improvement effects. Taken together, the results show that hippocampal memory consolidation processes do not require amygdala modulation. Arguments for an alternative view are presented suggesting that there are multiple memory consolidation pathways, one of which may depend on amygdala neural circuitry.     

Neurofeedback training in children with ADHD: 6-month follow-up of a randomised controlled trial

Neurofeedback (NF) could help to improve attentional and self-management capabilities in children with attention-deficit/hyperactivity disorder (ADHD). In a randomised controlled trial, NF training was found to be superior to a computerised attention skills training (AST) (Gevensleben et al. in J Child Psychol Psychiatry 50(7):780–789, 2009). In the present paper, treatment effects at 6-month follow-up were studied. 94 children with ADHD, aged 8–12 years, completed either 36 sessions of NF training (n = 59) or a computerised AST (n = 35). Pre-training, post-training and follow-up assessment encompassed several behaviour rating scales (e.g., the German ADHD rating scale, FBB-HKS) completed by parents. Follow-up information was analysed in 61 children (ca. 65%) on a per-protocol basis. 17 children (of 33 dropouts) had started a medication after the end of the training or early in the follow-up period. Improvements in the NF group (n = 38) at follow-up were superior to those of the control group (n = 23) and comparable to the effects at the end of the training. For the FBB-HKS total score (primary outcome measure), a medium effect size of 0.71 was obtained at follow-up. A reduction of at least 25% in the primary outcome measure (responder criterion) was observed in 50% of the children in the NF group. In conclusion, behavioural improvements induced by NF training in children with ADHD were maintained at a 6-month follow-up. Though treatment effects appear to be limited, the results confirm the notion that NF is a clinically efficacious module in the treatment of children with ADHD.     

Skill-memory consolidation in the striatum: critical for late but not early long-term memory and stabilized by cocaine

The sensorimotor striatum is important for procedural learning, including skill learning. Our previous findings indicate that this part of the striatum mediates the acquisition of a motor skill in a running-wheel task and that this skill learning is dependent on striatal D1 dopamine receptors. Here, we investigated whether the sensorimotor striatum is also involved in the consolidation of this skill memory and whether this consolidation is modified by the indirect dopamine receptor agonist cocaine. Rats were trained on a running wheel for 2 days (40 min/day) to learn a new motor skill, that is, the ability to control the movement of the wheel. Before each training session, the animals received an injection of vehicle or cocaine (25mg/kg, i.p.). Immediately following the training session, an intrastriatal infusion of 2% lidocaine (1 microl) or a sham infusion were administered. Wheel-skill performance was tested before and repeatedly after the training. Our results show that post-trial intrastriatal infusion of lidocaine disrupted late-stage long-term skill memory (post-training days 6-26), but spared early long-term memory (1 day after the training). Skill consolidation was more susceptible to such disruption in animals that practiced less during the training. Cocaine given pre-trial prevented this post-trial disruption of skill consolidation. These findings indicate that the sensorimotor striatum is critical for the consolidation of late but not early long-term skill memory. Furthermore, cocaine appeared to stabilize motor-memory formation by protecting consolidation processes after the training.     

Waking EEG power spectra in the rat: correlations with training performance

Adult rats chronically implanted with supradural electrodes were telemetrically EEG recorded during a baseline session, a training session for a two-way active avoidance task, and a retention session. Rats were assigned to a fast learning (FL), slow learning (SL) and non learning (NL) group if they achieved criterion during the training session, the retention session, or in neither session. High-resolution EEG analyses indicated that intergroup differences were present in the low frequency range of waking baseline power spectra. Moreover, baseline delta emissions directly correlated with freezings, and inversely correlated with avoidances, while emissions at 7-10 Hz directly correlated with avoidances and inversely correlated with freezings. Interestingly, during the first training period, waking delta emission selectively increased in FL rats in concomitance with a marked performance improvement; instead, SL and NL rats displayed increments at 7-9 Hz. In addition, freezings scored during the first two training periods directly correlated with post-training waking emission at 2 Hz, and inversely correlated with emission at 7-10 Hz. Conversely, escapes and avoidances directly correlated with waking emission at 7-10 Hz. The data indicate that (i) waking baseline power spectra differ among behavioral groups, and correlate with behavioral performance the following day; (ii) selective modifications of waking power spectra occur in each behavioral group during training; and (iii) behavioral responses during training correlate with post-training waking power spectra. Notably, the delta increment selectively occurring in training FL rats is assumed to reflect online memory processing leading to better performance. The latter observation supports the primary involvement of delta waves in learning.     

Dissociation between online and offline learning in developmental dyslexia

Most studies investigating procedural learning in developmental dyslexia (DD) have focused on the acquisition stage, ignoring later stages involved in the process of skill learning. The current study examined sequence learning among DD and control groups in two sessions. Both groups completed a sequence-learning task over a first session (online learning) and a second session 24 hours later (offline learning). While both groups showed improvements in performance during offline learning, only the control group showed improvements in performance during online learning. Moreover, the DD group differed from the control group in their ability to recover from the introduction of a different sequence.     

Memory impairment in rats by hippocampal administration of the serine protease subtilisin

Since the serine protease subtilisin has been reported to generate a novel form of long-term depression (LTD) in rat hippocampal slices, the present work was designed to determine whether it has any effect on learning and memory processes. Rats were used to examine the effects of subtilisin, injected directly into the dorsal hippocampus, on task performance in a step-through inhibitory avoidance of a mild footshock. The administration of 100 ng of subtilisin into each hippocampus, immediately after training, was sufficient to induce a detectable learning deficit with a footshock stimulus of 0.5 mA. Higher doses produced dose-related impairments in memory consolidation. These effects were not the result of irreversible toxicity, since rats trained with a higher amplitude footshock (0.75 mA) were able to perform as control animals; therefore, the amnesic effect was not further evident. Furthermore, the administration of subtilisin before avoidance training did not produce any detectable effect on performance during the training or test sessions, indicating that neither acquisition nor consolidation was affected. It is concluded that the post-training administration of a serine protease inhibitor is able to produce robust deficits of memory consolidation consistent with its ability to generate LTD, raising the possibility that related molecules could play physiological or pathological roles in the modulation of learning and memory.     

Age-related differences in sleep-dependent consolidation of motor skills in patients with narcolepsy type 1

ObjectiveThe influence of post-training sleep on the consolidation process of procedural (ie, visual and motor) knowledge has shown to be less effective in patients with chronic sleep disorders compared with healthy subjects. To ascertain whether the influence of the altered architecture of sleep in patients with narcolepsy type 1 (ie, with cataplexy: NT1) also varies with age, we compared the performance values of 16 children (aged from nine to 14 years) and 16 adults (aged from 24 to 51 years) on finger tapping task (FTT) after daytime and nighttime periods of sleep in the 24 hours following training.MethodsAll patients, who were drug-free and underwent continuous polysomnographic recordings, could take one or more naps after the training session (at 10 a.m.) until one hour before the first retrieval session (at 6 p.m.) and had an undisturbed period of nighttime sleep from about 10 p.m. to two hours before the second retrieval session (again at 10 a.m.).ResultsThe pattern of sleep-dependent consolidation was significantly different in the two groups of patients: while performance accuracy was higher in adults compared with children at each session, performance speed improved after daytime sleep in children and after nighttime sleep in adults. The improvement in performance speed, although not related with any sleep parameters in both groups, was positively correlated with the daytime and nighttime total sleep time (TST) in children with greater consolidation gain.ConclusionThe interaction between time of day and age in the time course of consolidation of new motor skills discloses a different role of daytime sleep (active in children, simply protective from interferences in adults) in NT1 patients and suggests a flexible use of napping in the educational context.     

The effect of spatio-temporal distance between visual stimuli on information processing in children with Specific Language Impairment

The purpose of this study is to evaluate whether children with Specific Language Impairment (SLI) have a deficit in processing a sequence of two visual stimuli (S1 and S2) presented at different inter-stimulus intervals and in different spatial locations. In particular, the core of this study is to investigate whether S1 identification is disrupted due to a retroactive interference of S2.To this aim, two experiments were planned in which children with SLI and children with typical development (TD), matched by age and non-verbal IQ, were compared (Experiment 1: SLI n = 19; TD n = 19; Experiment 2: SLI n = 16; TD n = 16).Results show group differences in the ability to identify a single stimulus surrounded by flankers (Baseline level). Moreover, children with SLI show a stronger negative interference of S2, both for temporal and spatial modulation.These results are discussed in the light of an attentional processing limitation in children with SLI.     

Chronic administration of fluoxetine impairs inhibitory avoidance in male but not female mice

The effects of chronic administration of fluoxetine (20 mg/kg/day i.p.) on a one-trial step-through inhibitory avoidance task were investigated in male and female CD1 mice. In Experiment 1, treatment was administered for 21 days before the training session, whereas in Experiment 2, other subjects were subjected to the same treatment starting 24 h after the training session. The comparison of test versus training latencies showed memory deterioration with pre-training administration of fluoxetine (Experiment 1), which affected males but not females. Sex differences in this task were also observed in Experiment 1, with females showing a better performance. Sex differences were evident in controls as well as in treated animals. The locomotor activity of the animals was also tested in Experiment 1. Due to the absence of sex differences in the drug effects on this measure, the sex differences in the effects of fluoxetine on inhibitory avoidance were hardly attributable to non specific effects on locomotor activity. The lack of effect of post-training administration of fluoxetine (Experiment 2) constitutes additional support of the idea that the observed effect on inhibitory avoidance in Experiment 1 is specifically related to learning and memory.     

Intracranial self-stimulation facilitates memory consolidation, but not retrieval: its effects are more effective than increased training.

To evaluate possible differential effects of lateral hypothalamic intracranial self-stimulation (ICSS) on memory consolidation and retrieval, independent groups of Wistar rats were trained in a single session of two-way active avoidance task (acquisition session) and tested 24 h later (retention session). The post-ICSS groups received an ICSS treatment immediately after the acquisition session, and the pre-ICSS groups received the same treatment immediately before the retention session. Because the ICSS effects on memory seem to be dependent on the initial performance level shown by the subjects, the possible influence of initial training (number of trials) on ICSS effects was also studied. Therefore, we used different control and experimental groups, which received either 30 or 50 trials in the acquisition session. Post-training ICSS facilitated the 24-h retention in both training conditions (30 and 50 trials). In contrast, pre-retention ICSS treatment did not facilitate performance in the retention test. We also observed that post-training ICSS was more effective for improving the 24-h retention than increasing the initial training from 30 to 50 trials. This findings confirm that ICSS treatment improves memory consolidation and suggest that it might not affect memory retrieval mechanisms.     

Age‐related differences in practice‐dependent resting‐state functional connectivity related to motor sequence learning

Decreased neural plasticity is observed with healthy ageing in the primary sensorimotor (SM1) cortex thought to participate in motor learning and memory consolidation processes. In the present magnetoencephalography study, the post‐training reorganization of resting‐state functional connectivity (rsFC) and its relation with motor learning and early consolidation in 14 young (19–30 years) and 14 old (66–70 years) healthy participants were investigated. At the behavioral level, participants were trained on a motor sequence learning task then retested 20–30 min later for transient offline gains in performance. Using a sensorimotor seed‐based approach, rsFC relying on beta band power envelope correlation was estimated immediately before and 10 min after the learning episode. Post‐training changes in rsFC (from before to after learning) were correlated with motor learning performance and with the offline improvement in performance within the hour after learning. Young and old participants exhibited differential patterns of sensorimotor‐related rsFC, bearing specific relationships with motor learning and consolidation. Our findings suggest that rsFC changes following learning reflect the offline processing of the new motor skill and contribute to the early memory consolidation within the hour after learning. Furthermore, differences in post‐training changes in rsFC between young and old participants support the hypothesis that ageing modulates the neural circuits underlying the learning of a new motor skill and the early subsequent consolidation stages. Hum Brain Mapp 38:923–937, 2017. © 2016 Wiley Periodicals, Inc.