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A randomized controlled trial of transcranial direct-current stimulation and cognitive training in children with fetal alcohol spectrum disorder
Abstract and Figures
Background
This study was a randomized double-blind sham-controlled trial examining the effects of transcranial direct current stimulation (tDCS) augmented cognitive training (CT) in children with Fetal Alcohol Spectrum Disorders (FASD). Prenatal alcohol exposure has profound detrimental effects on brain development and individuals with FASD commonly present with deficits in executive functions including attention and working memory. The most commonly studied treatment for executive deficits is CT, which involves repeated drilling of exercises targeting the impaired functions. As currently implemented, CT requires many hours and the observed effect sizes are moderate. Neuromodulation via tDCS can enhance brain plasticity and prior studies demonstrate that combining tDCS with CT improves efficacy and functional outcomes. TDCS-augmented CT has not yet been tested in FASD, a condition in which there are known abnormalities in neuroplasticity and few interventions.
Methods
This study examined the feasibility and efficacy of this approach in 44 children with FASD. Participants were randomized to receive five sessions of CT with either active or sham tDCS targeting the dorsolateral prefrontal cortex, a region of the brain that is heavily involved in executive functioning.
Results
The intervention was feasible and well-tolerated in children with FASD. The tDCS group showed nominally significant improvement in attention on a continuous performance test compared to sham (p=.043). Group differences were observed at the third, fourth and fifth treatment sessions. There was no effect of tDCS on working memory (p=.911). Further, we found no group differences on a trail making task (p=.659) or on the verbal fluency test (p=.826). In the active tDCS group, a significant correlation was observed between improvement in attention scores and decrease in parent-reported attention deficits (p=.010).
Conclusions
These results demonstrate that tDCS-augmented CT is well tolerated in children with FASD and potentially offers benefits over and above CT alone.
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... The group that received the combined method demonstrated a notably higher score increase. Moreover, in the evaluations of sustained attention, the group that received the combined method exhibited a more pronounced improvement The results of Boroda et al.'s study support the effectiveness of combining tDCS and cognitive behavioral training for children with Fetal Alcohol Spectrum Disorders (FASD) [30]. The study demonstrated that using anodal tDCS targeted at the left DLPFC with a bipolar montage (placing the anode at F3 and the cathode at Fp2) in conjunction with cognitive behavioral training led to more significant improvements in continuous performance tests for children with FASD compared to cognitive behavioral training alone [30]. ...
... Moreover, in the evaluations of sustained attention, the group that received the combined method exhibited a more pronounced improvement The results of Boroda et al.'s study support the effectiveness of combining tDCS and cognitive behavioral training for children with Fetal Alcohol Spectrum Disorders (FASD) [30]. The study demonstrated that using anodal tDCS targeted at the left DLPFC with a bipolar montage (placing the anode at F3 and the cathode at Fp2) in conjunction with cognitive behavioral training led to more significant improvements in continuous performance tests for children with FASD compared to cognitive behavioral training alone [30]. Our study's findings are in line with the research conducted by Alvarez-Alvarado et al. they demonstrated that the combination of cognitive behavioral training with active-tDCS, with stimulation delivered over F3 (cathode) and F4 (anode) electrode placements, resulted in sustained increases in excitatory neurotransmitter concentration [31]. ...
Background and Aim: Effective communication relies on understanding speech in noise, which can be challenging, especially for hearing-impaired children. Auditory attention influences speech perception in noise, and auditory attention training can help improve this critical auditory skill. Today’s neuromodulation methods are used in rehabilitation. Transcranial-Direct-Current-Stimulation (tDCS) is a promising approach among these methods. Our hypothesis was that combining electrical stimulation with behavioral auditory training could accelerate and enhance the effectiveness of auditory training, improving speech comprehension in noise. Methods: A pilot study was conducted on 8 children with moderate to severe hearing loss. In this study, tDCS was administered to the dorsolateral prefrontal cortexes in addition to behavioral auditory attention training. The participants were divided into two groups, one receiving real stimulation and the other receiving sham stimulation. 20 minutes of intervention were conducted through ten sessions. The Test-of-Everyday-Attention-for- Children (TEA-CH) and the monaural-Selective-Auditory-Attention-Test (mSAAT) tests were used as behavioral assessments, and the auditory P300 were recorded as an electrophysiological test to measure attention. Also, speech-in-noise tests were utilized. All tests were conducted before, immediately, and one month after training. Results: Children in both groups demonstrated noticeable progress in all tests following the training sessions. There was a significant difference in the level of improvement in mSAAT, TEA-CH, word-in-noise, and P300 latency between the two groups. Improvement was more remarkable in children receiving real stimulation. Conclusion: When behavioral attention training is combined with attention neuromodulation through tDCS, it may enhance rehabilitation effectiveness and increase the stability of tDCS effects.
... En población en desarrollo, también se han identificado algunas enfermedades con notable impacto del desenvolvimiento ejecutivo, algunas de ellas relacionadas con factores prenatales y perinatales como el trastorno alcohólico fetal (Boroda et al., 2020) y niños nacidos muy prematuros (Anderson et al., 2018), así como los sobrevivientes de algunas enfermedades como cáncer pediátrico (Benzing et al., 2022;Conklin et al., 2017) y malaria (Boivin et al., 2019), entre otras enfermedades menos frecuentes como el síndrome de corazón hipoplásico (Jordan et al., 2019) y la esclerosis múltiple infantil (Simone et al., 2018). Adicionalmente, se ha encontrado la incidencia de enfermedades relacionadas con el sistema nervioso como parálisis cerebral y la neurofibromatosis (Yoncheva et al., 2017). ...
... La estimulación de corriente continua transcraneal es una técnica neuromoduladora no invasiva, consiste en aplicar corrientes eléctricas de baja intensidad a través de electrodos ubicados sobre el cuero cabelludo, de manera que se logre modelar la actividad cerebral cortical. Ha comenzado a implementarse con moderación en niños con condiciones clínicas, mostrando mejoras notables sobre la atención y la memoria de trabajo (Boroda et al., 2020). Por otro lado, el entrenamiento en neurofeedback consiste en una técnica no invasiva que a partir del registro de las ondas cerebrales va suministrando retroalimentación al participante y, de esta manera, se va entrenando la capacidad de autocontrol sobre los patrones de actividad cerebral. ...
Este libro tiene el propósito de introducir a los maestros en un campo de las neurociencias cognitivas aplicadas a la educación, más específicamente al área del desarrollo de las funciones ejecutivas en la niñez. Esta obra está compuesta por cinco capítulos: el primero realiza una reflexión general sobre la relevancia del conocimiento de los maestros sobre el desarrollo neurológico y en particular de las funciones ejecutivas, así como contextualiza en referencia a las políticas públicas nacionales e internacionales. El segundo capitulo ofrece una conceptualización sobre la relación entre los mecanismos de autorregulación y las funciones ejecutivas; presenta un recorrido histórico del surgimiento del concepto “Funciones ejecutivas” y los aportes que se han realizado desde las neurociencias a la comprensión de este constructo, también se describe los sustratos neurológicos que soportan dichos procesos ejecutivos. El tercer capitulo presenta los modelos teóricos más representativos sobre las funciones ejecutivas. El cuarto capítulo ofrece un abordaje sobre el desarrollo de las funciones ejecutivas, empezando por las generalidades, seguido por una descripción de la maduración del sistema nervioso y si incidencia en las habilidades de función ejecutiva, continua con una descripción de las trayectorias de desarrollo de las funcione ejecutivas desde el modelo de Mikaye y por último describe los factores de riesgo y protectores en su desarrollo. El quinto y ultimo capitulo presenta una propuesta de intervención basada en los principios de la teoría ecológica del desarrollo y del nicho ecológico escolar, se definen los principios de la propuesta, sus componentes y la manera como pueden orquestarse para generar un nicho favorable para el desarrollo de las funciones ejecutivas. El libro finaliza presentando algunas estrategias basadas en la evidencia que favorecen el desarrollo de algunas funciones ejecutivas en contextos escolares.
... Measurable active-sham differences emerged by the third treatment visit, suggesting a synergistic effect between CT and tDCS with repeated administration. Similar findings of improved attention following 12-16 hours of CT training have been reported in individuals with fetal alcohol spectrum disorders [4]. A comprehensive meta-analysis encompassing 102 published tACS studies involving 2893 participants yielded compelling evidence of cognitive enhancement across nine distinct cognitive domains. ...
Background
Intellectual disability is a neurodevelopmental disorder characterized by significant impairments in intellectual functioning and adaptive behavior. Cognitive flexibility and attention are crucial cognitive domains often affected in children with intellectual disability. This case report explores the novel use of transcranial alternating current stimulation, a noninvasive brain stimulation technique, to enhance these cognitive functions. The study’s novelty lies in its focus on alpha-wave frequency transcranial alternating current stimulation targeting specific Brodmann areas and its potential sustained impact on cognitive flexibility and attention in the pediatric population with intellectual disability.
Case presentation
The case study involved two elementary school students, both 7 years old with mild intellectual disability, one male and one female, both with Turkic ethnicity, from Shahid Fahmideh School for Exceptional Children in Khosrowshah, Iran. Both participants underwent a 2-week intervention with daily 20-minute sessions of transcranial alternating current stimulation at an alpha-wave frequency (10 Hz), targeting Brodmann areas F3 and P3. Cognitive flexibility and attention were assessed using the Wisconsin Card Sorting Test and the Clock Test, administered at four time points: pre-intervention, week 1, week 2, and 1 month post-intervention. Statistical analysis showed significant improvements in both Wisconsin Card Sorting Test and Clock Test scores for both participants compared with baseline, with sustained enhancement over time.
Conclusion
The findings from this case report indicate that transcranial alternating current stimulation may be a promising intervention for improving cognitive flexibility and attention in children with intellectual disability. The significant and sustained improvements observed suggest that transcranial alternating current stimulation could have a meaningful clinical impact on the cognitive development of this population. However, further research is needed to confirm the efficacy of transcranial alternating current stimulation and to explore its broader applicability and long-term effects in larger, more diverse populations.
... La neuromodulación por aproximaciones no farmacológicas recientemente ha ganado fuerza en el terreno de la psiquiatría. Puntualmente, se ha reportado que la EECD favorece la neurogénesis y mejora el aprendizaje, por lo que se ha explorado su papel sobre la CPF como coadyuvante del entrenamiento cognitivo en niños con trastornos del espectro alcohólico fetal, especialmente observando una correlación significativa entre la mejora en las puntuaciones de atención y la disminución en los déficits de atención informados por los padres (Boroda et al., 2020). ...
Introduction: substance Use Disorder (SUD) is a public health problem that presents a need for innovation in therapeutic approaches. Considering the vast evidence of changes in neuroplasticity within the brain reward circuit, which is responsible for encoding the learning of substance use, it has been proposed to modulate neuroplasticity as a substrate in therapeutic approaches against addictions. Objective: analyze the recent available literature on the research of neuroplasticity as a therapeutic substrate for SUD. Method: a narrative review was carried out on articles indexed in the PubMed and Scopus databases from the last 5 years referring to neuroplasticity and the treatment of SUD. Results: the identified studies showed changes in the substance use learning process in animal models through various neuromodulation techniques, as well as proposals to reduce anxiety and relapses due to consumption through pharmacotherapy and non-invasive neuromodulation techniques in humans. Discussion and conclusions: although SUD treatment generates heterogeneous responses due to the nature of this condition, it is possible to offer therapeutic options with greater effectiveness by understanding the neuroplasticity changes associated with different drugs and neurostimulation techniques.
... In another study, it was determined that tDCS improved impulse control by regulating cognitive control (Weidler et al., 2022). Boroda et al. (2020) studied the hypothesis that tDCS application with cognitive training could have a significant effect on the increase of neuroplasticity in a study conducted with children with fetal alcohol syndrome. In the study, 2 mA of anodal tDCS was applied to the left dlPFC region of 38 children for 13 minutes. ...
Transcranial direct current stimulation (tDCS) is a promising research tool to address substance abuse, including alcohol, tobacco, opioid, and drug use disorders. The present literature review compared previous studies conducted with various current intensities, application regions, durations of stimulations, and different region targets of the brain. Studies based on the analyses conducted after tDCS administration in substance use disorder were promising for the use of tDCS as adjunctive therapy to reduce visible psychological and neurological symptoms of the addiction. Therefore, we aimed to provide an insight into the current state of research on tDCS as a therapeutic intervention in substance use disorders, identify gaps in the literature, and emphasize future investigation areas. Ultimately, the review sought to contribute to the understanding of the role of tDCS in addressing the complex challenges posed by substance use disorder, and its potential as a complementary or adjunctive treatment modality in addiction care. The present study identified that the left dlPFC and brain regions were effective targets for 1 mA and 2 mA tDCS current density in tobacco/nicotine use disorder. Also, the left dlPFC and 2 mA current density were identified as effective targets for tDCS in alcohol use disorder. Furthermore, left dlPFC and 2 mA current density were identified as effective targets for tDCS in opioid use disorder. Additionally, the right/left dlPFC, orbital frontal cortex, thalamus, and 2 mA current density were identified as effective targets for tDCS in other drug or substance use disorders. Animal studies demonstrated that tDCS was promising in reducing neuropathic pain, modulating neuropeptide Y activity, and reducing the redevelopment of ethanol consumption in animal models. However, further research is required to fully understand the optimal tDCS application parameters.
... Parkinson's patients receiving attention, processing speed, and working memory training with stimulation demonstrated increased motor skill improvements and reduced symptom scores compared to baseline [94]. Children with fetal alcohol syndrome who received DLPFC stimulation alongside cognitive training demonstrated improved attention scores and reported reduced attention deficits compared to sham stimulation [95]. Scores of attention and working memory were improved in unmedicated children with ADHD who received transcranial stimulation [96]. ...
Cancer survivors are at a high risk for treatment-related late effects, particularly neurocognitive impairment in the attention and executive function domains. These can be compounded in pediatric populations still undergoing neural development, which has increased interest in survivorship studies and neurorehabilitation approaches to mitigate these effects. Cognitive training regimens have shown promise as a therapeutic intervention for improving cognitive function. Therapist-guided and computerized training programs with adaptive paradigms have been successfully implemented in pediatric populations, with positive outcomes on attention and working memory. Another interventional approach is neuromodulation to alter plasticity. Transcranial electrical stimulation can modulate cortical surface activity, and cranial nerve stimulation alters autonomic activity in afferent brainstem pathways. However, they are more systemic in nature and have diffuse spatial targeting. Transcranial focused ultrasound (tFUS) modulation overcomes these limitations with high spatial specificity and the ability to target deeper brain regions. In this review, we discuss the efficacy of tFUS for modulating specific brain regions and its potential utility to augment cognitive training programs as a complementary intervention.
This review is focused on adult hippocampal neurogenesis as a potential therapeutic target in fetal alcohol spectrum disorder (FASD). Adult hippocampal neurogenesis refers to the production of new hippocampal dentate granule cells (DGCs) from a replenishable pool of neural stem and progenitor cells throughout life. Adult-generated DGCs have been shown to exert a profound influence on hippocampal network activity in experimental animals and have been implicated in the regulation of many hippocampal-dependent behaviors and emotional states, including certain forms of learning and memory, anxiety, mood, and stress resilience. While adult hippocampal neurogenesis in humans remains controversial, many studies support its existence and impact on hippocampal function in human health and disease. Here, we review mechanisms of adult hippocampal neurogenesis under physiological conditions, as described primarily in rodent brain, its impact on network activity and behavior, and the negative effects of developmental alcohol exposure on this process. We then explore hippocampal neurogenesis as a potential target for FASD therapy using pharmacological and neurophysiological approaches known to stimulate adult hippocampal neurogenesis, currently available for clinical use in FASD patients.
Prenatal alcohol exposure causes disruptions in brain development. The resulting disorder, fetal alcohol spectrum disorder (FASD), cannot be cured, but interventions can help improve the daily functioning of affected children and adolescents and the quality of life for the entire family.
The aim of the German guideline version 2024 is to provide validated and evidence-based recommendations on interventions for children and adolescents with FASD.
We searched for international guidelines and performed a systematic literature review and a hand search to identify literature (published 2012–2022) on interventions for children (0–18 years) with FASD. The quality of the literature was assessed for predefined outcomes using the GRADE method (grading of recommendations, assessment, development, and evaluation). We established a multidisciplinary guideline group, consisting of 15 professional societies, a patient support group, and 10 additional experts in the field. The group agreed on recommendations for interventions based on the systematic review of the literature and formulated additional recommendations, based on clinical experience/expert evidence in a formal consensus process.
No international guideline focusing on interventions for patients with FASD was found. Thirty-two publications (4 systematic reviews and 28 original articles) were evaluated. The analysis resulted in 21 evidence-based recommendations and 26 expert consensus, covering the following topics: neuropsychological functioning, adverse effects of therapy, complications/secondary conditions, quality of life, caregiver burden, knowledge of FASD, and coping and self-efficacy.
The German guideline is the first internationally to provide evidence-based recommendations for interventions in children and adolescents with FASD.
In utero alcohol exposure can disrupt the development of the fetal brain and result in a wide range of neurobehavioral outcomes collectively known as fetal alcohol spectrum disorders (FASD). This paper provides a comprehensive review of the cognitive and behavioral outcomes of prenatal alcohol exposure, including domains of general intelligence, executive functioning, language development, learning and memory, adaptive functioning, academic performance, and concurrent psychopathology. In addition, the current status of the neurobehavioral profile of FASD and its potential as a diagnostic tool will be discussed.
Background: Brain training products are becoming increasingly popular for children and adolescents. Despite the marketing aimed at their use in the general population, these products may provide more benefits for specific neurologically impaired populations. A review of Brain Training (BT) products analyzing their efficacy while considering the methodological limitations of supporting research is required for practical applications.
Method: searches were made of the PubMed database (until March 2017) for studies including: (1) empirical data on the use of brain training for children or adolescents and any effects on near transfer (NT) and/or far transfer (FT) and/or neuroplasticity, (2) use of brain training for cognitive training purposes, (3) commercially available training applications, (4) computer-based programs for children developed since the 1990s, and (5) relevant printed and peer-reviewed material.
Results: Database searches yielded a total of 16,402 references, of which 70 met the inclusion criteria for the review. We classified programs in terms of neuroplasticity, near and far transfer, and long-term effects and their applied methodology. Regarding efficacy, only 10 studies (14.2%) have been found that support neuroplasticity, and the majority of brain training platforms claimed to be based on such concepts without providing any supporting scientific data. Thirty-six studies (51.4%) have shown far transfer (7 of them are non-independent) and only 11 (15.7%) maintained far transfer at follow-up. Considering the methodology, 40 studies (68.2%) were not randomized and controlled; for those randomized, only 9 studies (12.9%) were double-blind, and only 13 studies (18.6%) included active controls in their trials.
Conclusion: Overall, few independent studies have found far transfer and long-term effects. The majority of independent results found only near transfer. There is a lack of double-blind randomized trials which include an active control group as well as a passive control to properly control for contaminant variables. Based on our results, Brain Training Programs as commercially available products are not as effective as first expected or as they promise in their advertisements.
Objective
To compare the use of the Continuous Performance Task (CPT) reaction time variability (intraindividual variability or standard deviation of reaction time), as a measure of vigilance in attention-deficit hyperactivity disorder (ADHD), and stimulant medication response, utilizing a simple CPT X-task vs an A-X-task.
Method
Comparative analyses of two separate X-task vs A-X-task data sets, and subgroup analyses of performance on and off medication were conducted.
Results
The CPT X-task reaction time variability had a direct relationship to ADHD clinician severity ratings, unlike the CPT A-X-task. Variability in X-task performance was reduced by medication compared with the children’s unmedicated performance, but this effect did not reach significance. When the coefficient of variation was applied, severity measures and medication response were significant for the X-task, but not for the A-X-task.
Conclusion
The CPT-X-task is a useful clinical screening test for ADHD and medication response. In particular, reaction time variability is related to default mode interference. The A-X-task is less useful in this regard.
Most transcranial Direct Current Stimulation (tDCS) trials of schizophrenia administer few sessions and do not assess transfer effects to other cognitive domains. In a randomized, double-blind, sham-controlled, parallel groups trial, we determined the extent to which 4-weeks of 2 mA tDCS at 20 min/day totalling 20 tDCS sessions administered during a spatial working memory test, with anodal right dorsolateral prefrontal cortex (DLPFC) and cathodal left tempo-parietal junction (TPJ) placement, as an adjunct to antipsychotics reduced auditory hallucinations and improved cognition in 12 outpatients with schizophrenia. Anodal tDCS significantly improved language-based working memory after 2 weeks and verbal fluency after 2 and 4 weeks. Thus, four weeks of tDCS appears to be safe and elicits transfer benefits to other prefrontal-dependent cognitive abilities in schizophrenia.
Aims: To examine and compare sensory processing in children diagnosed with Fetal Alcohol Spectrum Disorder (FASD) to children designated as “at risk” for neurodevelopmental disorders and FASD, associated with Prenatal Alcohol Exposure (PAE). Method: A retrospective chart review methodology was applied to examine sensory processing in a clinic referred sample of 90 children under the age of 3 with PAE of which 28 children were diagnosed with FASD and 62 were in the “at risk” category. Results: Young children with FASD rated significantly lower on the Infant/Toddler Sensory Profile in auditory processing and low registration and more often in the probable difference range in sensory sensitivity and sensation avoiding. Some children in both groups demonstrated definite differences in low threshold scores. Conclusions: Sensory processing differences in young children with FASD are supported when compared to children with PAE who are “at risk” for future diagnoses. Occupational therapists should consider sensory processing when assessing and providing early intervention services to this population.
Transcranial direct current stimulation (tDCS) provides a means of non-invasively inducing plasticity-related changes in neural circuits in vivo and is experiencing increasing use as a potential tool for modulating brain function. There is growing evidence that tDCS-related outcomes are likely to be influenced by an individual's brain state at the time of stimulation, i.e., effects show a degree of ‘state-dependency’. However, few studies have examined the behavioural and physiological impact of state-dependency within cognitively salient brain regions. Here, we applied High-Definition tDCS (HD-tDCS) over the left dorsolateral prefrontal cortex (DLPFC) in 20 healthy participants, whilst they either remained at rest, or performed a cognitive task engaging working memory (WM). In a third condition sham stimulation was administered during task performance. Neurophysiological changes were probed using TMS-evoked potentials (TEPs), event-related potentials (ERPs) recorded during n-back WM tasks, and via resting-state EEG (RS-EEG). From a physiological perspective, our results indicate a degree of neuromodulation following HD-tDCS, regardless of task engagement, as evidenced by changes in TEP amplitudes following both active stimulation conditions. Changes in ERP (P3) amplitudes were also observed for the 2-Back task following stimulation delivered during task performance only. However, no changes were seen on RS-EEG for any condition, nor were any group-level effects of either stimulation condition observed on n-back performance. As such, these findings paint a complex picture of neural and behavioural responses to prefrontal stimulation in healthy subjects and provide only limited support for state-dependent effects of HD-tDCS over the DLPFC overall.
(Abstracted from JAMA Pediatr 2017;171(10):948–956)
Fetal alcohol spectrum disorder (FASD) is an umbrella term for the wide range of adverse effects to the developing fetus when exposed to alcohol during pregnancy, some of which are lifelong. The severity and type of defects induced by FASD are affected by the age of embryo at exposure, pattern of exposure, and dose; however, other factors including genetic background, maternal age, and environmental influences also appear to impact susceptibility.
Introduction:
Short-term memory refers to the capacity for holding information in mind for a short period of time with conscious memorization. It is an important ability for daily life and is impaired in several neurological and psychiatric disorders. Anodal transcranial direct current stimulation (tDCS) applied to the dorsolateral prefrontal cortex (DLPFC) was reported to enhance the capability of short-term memory in healthy subjects. However, results were not consistent and what is the possible impact factor is not known. One important factor that may significantly influence the effect of tDCS is the timing of tDCS administration.
Aims:
In order to explore whether tDCS impact short-term memory and the optimal timing of tDCS administration, we applied anodal tDCS to the left DLPFC to explore the modulatory effect of online and off-line tDCS on digit span as well as visual short-term memory performance in healthy subjects.
Results:
Results showed tDCS of the left DLPFC did not influence intentional digit span memory performance, whether before the task or during the task. In addition, tDCS of the DLPFC administered before the task showed no effect on visual short-term memory, while there was a trend of increase in false alarm when tDCS of the DLPFC administered during the task.
Conclusions:
These results did not provide evidence for the enhancement of short-term memory by tDCS of the left DLPFC in healthy subjects, but it suggested an importance of administration time for visual short-term memory. Further studies are required to taking into account the baseline performance of subjects and time-dependence feature of tDCS.
Individuals prenatally exposed to alcohol often have impaired spatial working memory (SWM). This study examines functional connections of frontal and parietal regions that support SWM in children with and without prenatal alcohol exposure. Children ages 10 to 16 with histories of heavy prenatal alcohol exposure (AE group; n = 18) and controls (CON group; n = 19) underwent functional magnetic resonance imaging (fMRI) while performing a SWM task. Whole brain task-related functional connectivity of bilateral dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex (PPC) seed regions were estimated for each participant using a psychophysiological interaction approach. Children in the AE group were less accurate than children in the CON group when performing the SWM task (p = 0.008). Positive coupling between bilateral DLPFC seeds and regions within the fronto-parietal network was observed in the CON group, whereas the AE group showed negative connectivity. In contrast to the CON group, the AE group showed positive connectivity between PPC seeds and frontal lobe regions. Across seeds, decreased negative coupling with regions outside the fronto-parietal network (e.g., left middle occipital gyrus) were observed in the AE group relative to the CON group. Functional data clusters were considered significant at p < 0.05. Overall findings suggest that localized alterations in neural activity, aberrant fronto-parietal network synchrony, and poor coordination of neural responses with regions outside of this network may help explain SWM deficits in individuals with a history of heavy prenatal alcohol exposure.
There is considerable interest in maintaining working memory (WM) because it is essential to accomplish most cognitive tasks, and it is correlated with fluid intelligence and ecologically valid measures of daily living. Toward this end, WM training protocols aim to improve WM capacity and extend improvements to unpracticed domains, yet success is limited. One emerging approach is to couple WM training with transcranial direct current stimulation (tDCS). This pairing of WM training with tDCS in longitudinal designs promotes behavioral improvement and evidence of transfer of performance gains to untrained WM tasks. However, the mechanism(s) underlying tDCS-linked training benefits remain unclear. Our goal was to gain purchase on this question by recording high-density EEG before and after a weeklong WM training + tDCS study. Participants completed four sessions of frontoparietal tDCS (active anodal or sham) during which they performed a visuospatial WM change detection task. Participants who received active anodal tDCS demonstrated significant improvement on the WM task, unlike those who received sham stimulation. Importantly, this pattern was mirrored by neural correlates in spectral and phase synchrony analyses of the HD-EEG data. Notably, the behavioral interaction was echoed by interactions in frontal-posterior alpha band power, and theta and low alpha oscillations. These findings indicate that one mechanism by which paired tDCS + WM training operates is to enhance cortical efficiency and connectivity in task-relevant networks.