V5/MT Stimulation on Reading and Reading-related Measures in Developmental Dyslexia

Официальное название

Probing the Efficacy of V5/MT Stimulation on Reading and Reading-related Measures in Children and Adolescents With Developmental Dyslexia

Обзор

The present study grounds on the absence of evidence-based treatment in individuals with developmental dyslexia (DD). At this topic, the present study will explore the potential effect of transcranial direct current stimulation (tDCS) over left hemispheric direct Lateral Geniculate Nucleus (LGN)-V5/MT pathway, cerebral areas usually disrupted in individuals with DD. The investigators hypothesized that active tDCS over V5/MT will boost reading skills in children and adolescents with DD. On the contrary, sham (placebo condition) tDCS over V5/MT or active (control condition) tDCS over V1 will not have significant effect in improving reading skills. Further, both active and sham tDCS will be safe and well tolerated.

Подробное описание

Over the last few decades, a huge number of studies has revealed that Developmental Dyslexia (DD), a brain-based neurodevelopmental disorder characterized by a severe and persistent impairment in the acquisition of reading skills may depend on multiple neurocognitive impairments, ranging from language-specific to cognitive-general deficits. Besides the most influential hypothesis of a phonological core deficit, there is also evidence for difficulties in low-level visual-temporal information processing, as the magnocellular deficit theory supports, as well as for visual-spatial attentional deficits, visual-perceptual impairments, and rapid automatized naming (RAN)-speed deficits.

Replicated structural/functional neuroimaging studies have demonstrated a DD hypoactivation relative to typical readers in the left temporo-occipital regions-critical for the automatic visual processing of word strings or print-and in the left temporo-parietal regions-important for grapheme-to-phoneme mapping.

Moreover, findings from animal models and post mortem studies in humans suggest that DD might also be associated with structural alterations in subcortical sensory pathways, particularly in visual and auditory thalamic nuclei and in their connections with high-order sensory cortices (i.e., the left hemispheric direct Lateral Geniculate Nucleus (LGN)-V5/MT pathway and the left hemispheric direct Medial Geniculate Body (MGB)-mPT pathway). In addition, in adults with DD, left V5/MT-LGN connectivity strength correlated with RAN abilities - a key deficit in DD.

A number of studies have demonstrated the positive effect of transcranial direct current stimulation (tDCS), a non-invasive brain stimulation used for transiently modifying neural activity of target areas, on reading and, particularly, in DD.

However, the few non-invasive brain stimulation studies on improving reading in DD yielded heterogeneous results and this variability might be partly due to the lack of neurobiological understanding of the underlying DD mechanism or to the use of traditional tDCS rather than a more focal technique such as the high-definition tDCS (HD-tDCS).

Starting from this, the aim of the current study is testing the effectiveness of a cutting-edge stimulation technique (i.e., HD-tDCS) in a within-subject experiment involving children and adolescents with DD. Especially, we will work to test i) the specific effect of HD-tDCS over high-order sensory cortices (i.e., V5/MT vs V1) on reading in children with DD; ii) the preconditions and neurobiological mechanisms that lead to high treatment outcomes.

If the stimulation over V5/MT is effective and specifically related to reading improvement, our results could help to i) understand the contribution and neurobiological mechanism of V5/MT in reading of children and adolescents with DD; ii) select criteria for potential responders to non-invasive brain stimulation; iii) develop evidence-based interventions in DD.

Вмешательства

• Устройство Active HD-tDCS over V5/MT
  For HD-tDCS a 4 × 1 montage (Kessler et al., 2013), small circular electrodes (diameter 1 cm) will be used with the anode placed centrally with a current intensity of 1 mA for a total of 20 minutes (30 s ramp up/down). Hereby, the anodal electrode modulates the excitability of the targeted area left V5/MT, whereas the other 4 electrodes return electrical currents that flow away from that area. V5/MT will be localised via published procedures and electrode's placement will be done according to th
• Устройство Active HD-tDCS over V1
  For HD-tDCS a 4 × 1 montage (Kessler et al., 2013), small circular electrodes (diameter 1 cm) will be used with the anode placed centrally with a current intensity of 1 mA for a total of 20 minutes (30 s ramp up/down). Hereby, the anodal electrode modulates the excitability of the targeted area left V1, whereas the other 4 electrodes return electrical currents that flow away from that area. V1 will be localised via published procedures and electrode's placement will be done according to the 10-2
• Устройство Sham HD-tDCS over V5/MT or V1
  Sham HD-tDCS will be delivered over left V5/MT or left V1. The same electrodes placement as well as the stimulation set-up will be used as in the active stimulation conditions, but the current will be applied for 30 s and will be ramped down (0 mA) during the rest of the session without the participants awareness. .

Первичные конечные точки

• Text reading accuracy (Experimental reading task) [Срок оценки: during procedure]
• Text reading speed (Experimental reading task) [Срок оценки: during procedure]

Вторичные конечные точки (9)

• Word reading accuracy (Experimental reading task) [Срок оценки: during procedure]
• Word reading speed (Experimental reading task) [Срок оценки: during procedure]
• Non-word reading accuracy (Experimental reading task) [Срок оценки: during procedure]
• Non-word reading speed (Experimental reading task) [Срок оценки: during procedure]
• Right visual hemisphere-motion perception (Experimental reading task) [Срок оценки: during procedure]
• Rapid automatized naming letter and number (Experimental reading task) [Срок оценки: during procedure]
• Phoneme blending (Experimental reading task) [Срок оценки: during procedure]
• Eye-movements during reading (Experimental reading task) [Срок оценки: during procedure]
• Spontaneous EEG (Experimental reading task) [Срок оценки: during procedure]

Критерии участия

Критерии включения

• Italian speakers right-handed children and adolescents with dyslexia (DSM-5, APA 2013);
• Word/nonword/text reading accuracy and/or speed at least 2 Standard Deviations below the mean for school-age;
• nv IQ ≥ 85;
• normal hearing and normal or corrected-to-normal vision.

Критерии исключения

• Having a comorbidity with other primary psychiatric/neurological diagnosis (e.g., depression, anxiety, autism, ADHD);
• Having a personal history of neurological/medical/genetic diseases;
• Having ongoing drug treatment influencing brain function;
• Having epilepsy o family history of epilepsy.

Критерии приведены из реестра в оригинале (на английском). Окончательную оценку соответствия проводит исследовательский центр.

Здоровые добровольцы: Да

Дизайн исследования

Распределение

Рандомизированное

Модель

Перекрёстный дизайн

Маскирование

Двойное слепое

Основная цель

Лечение

Центры проведения

Италия · 1 центр

• Bambino Gesù Hospital and Research Institute — Roma

Публикации

• American Psychiatric Association. Diagnostic and statistical manual of mental disorders (5th ed.): DSM 5. Washington, DC: American Psychiatric Association. 2013.
• Snowling, M. Dyslexia, 2nd ed.; Blackwell Publishing: Oxford, UK. 2000.
• Wolf M, Bowers PG. The double-deficit hypothesis for the developmental dyslexias. Journal of Educational Psychology. 1999; 91(3): 415-438.
• Menghini D, Finzi A, Benassi M, Bolzani R, Facoetti A, Giovagnoli S, Ruffino M, Vicari S. Different underlying neurocognitive deficits in developmental dyslexia: a comparative study. Neuropsychologia. 2010 Mar;48(4):863-72. doi: 10.1016/j.neuropsychologia.2009.11.003. Epub 2009 Nov 10. PMID 19909762
• Vellutino FR, Fletcher JM, Snowling MJ, Scanlon DM. Specific reading disability (dyslexia): what have we learned in the past four decades? J Child Psychol Psychiatry. 2004 Jan;45(1):2-40. doi: 10.1046/j.0021-9630.2003.00305.x. PMID 14959801
• Melby-Lervag M, Lyster SA, Hulme C. Phonological skills and their role in learning to read: a meta-analytic review. Psychol Bull. 2012 Mar;138(2):322-52. doi: 10.1037/a0026744. Epub 2012 Jan 16. PMID 22250824
• Schulte-Korne G, Bruder J. Clinical neurophysiology of visual and auditory processing in dyslexia: a review. Clin Neurophysiol. 2010 Nov;121(11):1794-809. doi: 10.1016/j.clinph.2010.04.028. Epub 2010 May 31. PMID 20570212
• Vidyasagar TR, Pammer K. Dyslexia: a deficit in visuo-spatial attention, not in phonological processing. Trends Cogn Sci. 2010 Feb;14(2):57-63. doi: 10.1016/j.tics.2009.12.003. Epub 2010 Jan 14. PMID 20080053

Идентификаторы

NCT: NCT05972200 · 3073_OPBG_2023

Первоисточники (государственные реестры)

• ClinicalTrials.gov (NIH, США)

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