Long-term memory formation for voices during sleep in three-month-old infants.

The ability to form long-term memories begins in early infancy. However, little is known about the specific mechanisms that guide memory formation during this developmental stage. We demonstrate the emergence of a long-term memory for a novel voice in three-month-old infants using the EEG mismatch response (MMR) to the word "baby". In an oddball-paradigm, a frequent standard, and two rare deviant voices (novel and mother) were presented before (baseline), and after (test) familiarizing the infants with the novel voice and a subsequent nap. Only the mother deviant but not the novel deviant elicited a late frontal MMR (∼850 ms) at baseline, possibly reflecting a long-term memory representation for the mother's voice. Yet, MMRs to the novel and mother deviant significantly increased in similarity after voice familiarization and sleep. Moreover, both MMRs showed an additional early (∼250 ms) frontal negative component that is potentially related to deviance processing in short-term memory. Enhanced spindle activity during the nap predicted an increase in late MMR amplitude to the novel deviant and increased MMR similarity between novel and mother deviant. Our findings indicate that the late positive MMR in infants might reflect emergent long-term memory that benefits from sleep spindles.

Signs of enhanced formation of gist memory in children with autism spectrum disorder - a study of memory functions of sleep.

BACKGROUND: Autism spectrum disorder (ASD) is characterized by impaired cognitive and social skills, including emotional dysregulation, and symptoms have been suspected to partly arise from impaired formation of memory representations regulating these behaviours. Sleep, which is subjectively impaired in ASD, is critical for forming long-term memories and abstracted gist-based representations. We expected a generally reduced memory benefit from sleep in children with ASD, and a diminished enhancement of gist representations, in particular. METHODS: We compared effects of sleep on memory consolidation between boys (9-12 years) with ASD (n = 21) and typically developing (TD, n = 20) boys, matched for age and IQ, in a within-subjects crossover design. We employed an emotional picture recognition task and the Deese-Roediger-McDermott (DRM) word list task for assessing gist memory formation in the emotional and nonemotional domain, respectively. Learning took place before retention intervals of nocturnal sleep and daytime wakefulness, and retrieval was tested afterwards. RESULTS: Surprisingly, on the DRM task, children with ASD showed an enhanced sleep-dependent formation of gist-based memory (i.e. more recall of 'critical lure words' after sleep compared to wakefulness) than TD children, with this effect occurring on top of a diminished veridical word memory. On the picture recognition task, children with ASD also showed a stronger emotional enhancement in memory (i.e. relatively better memory for negative than neutral pictures) than TD children, with this enhancement occurring independent of sleep. Sleep polysomnography was remarkably comparable between groups. CONCLUSIONS: Children with ASD show well-preserved sleep-dependent memory consolidation. Enhanced gist memory formation in these children might reflect a compensatory response for impairments at earlier stages of memory processing, that is during encoding.

Imagine squeezing a cactus: Cortical activation during affective motor imagery measured by functional near-infrared spectroscopy.

The activation of different brain areas during kinaesthetic and visual motor imagery has been extensively studied, whereas little is known about affective motor imagery, i.e. the imagery of pleasant/unpleasant movements. In the present neuroimaging study we investigated cortical activation of kinaesthetic motor imagery (KMI) based on emotional stimulus content by means of functional near infrared spectroscopy (fNIRS). Twenty healthy adult participants were instructed to imagine affective, and neutral motor tasks while multichannel fNIRS was recorded simultaneously. In the affective MI condition they had to imagine e.g. squeezing a cactus with their right hand several times, eliciting an unpleasant emotion. In the neutral condition their task was to imagine squeezing a ball. Significant differences in oxy-hemoglobin [oxy-Hb] concentration changes during KMI including affective objects in different brain regions were found. Specifically activation in left parietal and frontal regions was increased during the imagery of squeezing a cactus which induced a painful feeling. Both areas are also involved in the perception of pain and commonly labelled as parts of the "pain matrix". Our study provides novel insights in cortical activation patterns during affective motor imagery and its psychological and cognitive mechanisms underlying pain experience.

Towards using fNIRS recordings of mental arithmetic for the detection of residual cognitive activity in patients with disorders of consciousness (DOC).

BACKGROUND: Recently, fNIRS has been proposed as a promising approach for awareness detection, and a possible method to establish basic communication in patients with disorders of consciousness (DOC). AIM: Using fNIRS, the present study evaluated the applicability of auditory presented mental-arithmetic tasks in this respect. METHODS: We investigated the applicability of active attention to serial subtractions for awareness detection in ten healthy controls (HC, 21-32 y/o), by comparing the measured patterns to patterns induced by self-performance of the same task. Furthermore, we examined the suitability of ignoring the given task as additional control signal to implement a two-class brain-computer interface (BCI) paradigm. Finally, we compared our findings in HC with recordings in one DOC patient (78 y/o). RESULTS AND CONCLUSION: Results of the HC revealed no differences between the self-performance and the attention condition, making the attention task suitable for awareness detection. However, there was no general difference between the ignore and attend condition, making the tasks less suitable for BCI control. Despite inconsistent correlations between the patient data and the HC group, single runs of the patient recordings revealed task-synchronous patterns - however, we cannot conclude whether the measured activation derives from instruction based task performance and thus awareness.

Investigation of the influence of 45-minute pre-sleep social media use on sleep quality and memory consolidation in adolescents.

Adolescents devote a significant portion of their time to smartphone usage, often engaging in social media activities. Social media use has previously been linked to diminished sleep quality and reduced sleep durations in correlational studies. In this experimental study, we aimed to investigate the influence of pre-sleep social media use on memory consolidation, subjective arousal and objectively assessed sleep quality in adolescents. We compared the social media condition to two reading conditions, one involving reading a book on a smartphone and the other reading from a physical book in a within-subjects design. Twenty participants between 12 and 14 years engaged in these activities for 45 min before bedtime. Contrary to our expectations, the results indicated that pre-sleep social media use did not have a discernible impact on sleep quality, pre-sleep arousal or memory consolidation. All assessed sleep measures remained consistent across the three conditions. Subjectively, the social media condition was rated less thrilling than the reading conditions. This suggests that, within the confines of this experiment, pre-sleep social media exposure did not significantly disrupt adolescents' sleep or their ability to consolidate memories during sleep. This deviation from previous correlational studies might be explained by a possible impact of mental health factors on media consumption and sleep or the fact that contrary to their daily routines participants had to sleep after our intervention and could not continue to engage in their activities. This highlights the need for further investigations into the complexities of this interaction.

Sleep electroencephalogram (EEG) oscillations and associated memory processing during childhood and early adolescence.

The architecture of sleep undergoes distinct changes during childhood and early adolescence. Slow wave sleep is involved in memory processing and may support active consolidation of newly encoded representations to support the formation of abstracted "gist" memories. Here, we examined sleep and overnight memory formation in German school children (n = 33) between 7 and 15 years of age, after the encoding phase of a verbal Deese-Roediger-McDermott (DRM) task. Effects of age were analyzed on sleep electroencephalogram (EEG) signatures of memory processing during nonrapid eye movement (NonREM) sleep, and the overnight formation of veridical and gist-based memories. Increasing age decreases time spent in slow wave sleep, and slow wave activity, whereas density and amplitude of fast sleep spindles in NonREM sleep were increased. Moreover, fast spindles were more consistently and more closely coupled to the upstate of the slow oscillation in the older children. Also, veridical and gist-based recall of words after sleep increased with age. Notably, a closer slow oscillation upstate-fast spindle coupling predicted veridical recall of words, and this relationship was found independent of age. Memory performance in the sleeping children did not differ from that of an age-matched control group (n = 32) tested over a daytime wake retention interval, with adolescents even showing superior veridical recall after wake. Our findings suggest that slow oscillation-spindle coupling as a mechanism of sleep-dependent memory formation becomes increasingly relevant during childhood and early adolescence. However, wake-associated mechanisms similarly effective in forming medium-term memory exist in this age as well. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

How do children with autism spectrum disorder form gist memory during sleep? A study of slow oscillation-spindle coupling.

Sleep is assumed to support memory through an active systems consolidation process that does not only strengthen newly encoded representations but also facilitates the formation of more abstract gist memories. Studies in humans and rodents indicate a key role of the precise temporal coupling of sleep slow oscillations (SO) and spindles in this process. The present study aimed at bolstering these findings in typically developing (TD) children, and at dissecting particularities in SO-spindle coupling underlying signs of enhanced gist memory formation during sleep found in a foregoing study in children with autism spectrum disorder (ASD) without intellectual impairment. Sleep data from 19 boys with ASD and 20 TD boys (9-12 years) were analyzed. Children performed a picture-recognition task and the Deese-Roediger-McDermott (DRM) task before nocturnal sleep (encoding) and in the next morning (retrieval). Sleep-dependent benefits for visual-recognition memory were comparable between groups but were greater for gist abstraction (recall of DRM critical lure words) in ASD than TD children. Both groups showed a closely comparable SO-spindle coupling, with fast spindle activity nesting in SO-upstates, suggesting that a key mechanism of memory processing during sleep is fully functioning already at childhood. Picture-recognition at retrieval after sleep was positively correlated to frontocortical SO-fast-spindle coupling in TD children, and less in ASD children. Critical lure recall did not correlate with SO-spindle coupling in TD children but showed a negative correlation (r = -.64, p = .003) with parietal SO-fast-spindle coupling in ASD children, suggesting other mechanisms specifically conveying gist abstraction, that may even compete with SO-spindle coupling.

Improved concept and first results of an auditory single-switch BCI for the future use in disorders of consciousness patients.

A promising approach to establish basic communication for disorders of consciousness (DOC) patients, is the application of Brain-Computer Interface (BCI) systems, especially the use of single-switch BCIs (ssBCIs). Recently we proposed the concept of a novel auditory ssBCI paradigm and presented first classification results. In this study we report on the evaluation of four different modifications of the original paradigm with the intention to increase the suitability. Therefore we investigated different sound types and the inclusion of additional spatial information. Finally, the classification investigation with the most encouraging modifications shows an enhancement compared to our original paradigm, within healthy subjects, implicating better results for the future use in DOC patients.