NEUROIMAGING OF THE READING BRAIN

Capturing letter and sound learning in typical and dyslexic readers 

MileneBonte 

Maastricht Brain Imaging Center, Maastricht University, Netherlands 

Abstract: The formation of efficient associations between visual and spoken language representations forms a fundamental step in reading development. Although we have a fairly good understanding of how our brain processes already learnt associations, we know very little about underlying learning processes. In this talk I will discuss how behavioural, EEG and fMRI measures can be used to track neurobehavioral changes during letter and speech sound learning, and how these changes may relate to dyslexia. 

Early reading skills and the ventral occipito-temporal cortex organization 

Chyl, K.¹,Gentile, F.², Dębska, A.¹, Wójcik, M.¹, Bonte, M.², Jednoróg, K.¹ 

 ¹Laboratory of Language Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland 
²Maastricht Brain Imaging Center and Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands 

Abstract: Learning to read impacts the way the ventral occipitotemporal cortex (VOT) reorganizes. The postulated underlying mechanism of neuronal recycling was recently revisited. An experimental data showed that voxels weakly specialized for visual processing keep their initial category selectivity, while acquiring an additional, stronger responsivity to written words. Here, we examined a large and diverse group of six-year-olds prior to literacy training (N = 72) using various data analysis techniques (univariate, multivariate, rapid adaptation) and types of stimuli (print, symbols, houses, faces) to further explore how VOT changes and adapts to reading. We found that only print activated a wide network of language related areas outside of the bilateral VOT, and the level of reading skill was related to the extent and strength of this activation. Adaptation effect was not directly related to the level of reading skill, but revealed the emergence of the reading network in readers. Importantly, we found that the reorganization of the VOT is not an “invasion” by reading acquisition - voxels previously activated for faces started to respond more for print, while at the same time keeping their previous function. We can thus conclude that the revised hypothesis of neuronal recycling is supported by our data. 

Funding:  This study was funded by the Polish National Science Center (grants 2014/14/A/HS6/00294 and 2019/32/T/HS6/00270). 

The development of the orthography-phonology integration in occipitotemporal cortex and its relations to the reading acquisition 

Dębska, A., Chyl, K. Wójcik, M., Jednoróg, K. 

Laboratory of Language Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland 

Abstract: The region of the left ventral occipitotemporal cortex (VOTc) encompassing Visual Word Form Area is considered to host orthographic representations of words. Even though this area was studied in visual word processing, there is evidence of multimodal engagement of the left VOTc in spoken language. It is supposed to facilitate the integration of phonological and orthographical representations needed for an effective reading acquisition. To investigate the development of the left posterior and anterior VOTc involvement in spoken language processing and its relations to the reading ability we tested 47 Polish beginning readers at the beginning of the formal literacy acquistion and two years later. In fMRI tasks children had to decide whether two auditory words start with the same sound (phoneme matching), if they rhyme (rhyming) or if they are identical (word matching). Univariate and multivariate approaches showed the increase of integration proccess with the time of schooling. The most relevant integration processes occurs on a smallest grain size of phonological processing in agreement with the high transparency of Polish orthography and differently than in opaque English orthography.  

Funding:  This research has been made possible by the Kosciuszko Foundation scholarship at Vanderbilt University, Nashville,TN.

Investigating Neural Noise in Dyslexia Using Functional Magnetic Resonance Spectroscopy (fMRS) and EEG Power Spectrum 

Katarzyna Wasilewska¹, Agnieszka Glica¹, Bartosz Kossowski², Katarzyna Jednoróg¹ 

¹Laboratory of Language Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland 
²Laboratory of Brain Imaging, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland

Abstract: Dyslexia is a developmental disorder characterized by a specific difficulty in learning to read and write that cannot be explained by low intellectual level or by incorrect teaching methods in school. According to the neural noise hypothesis, dyslexia is a consequence of disturbance in synaptic transmission. In particular, an imbalance between main excitatory (glutamate) and main inhibitory neurotransmitter (GABA) is assumed – specifically with elevated glutamate concentrations in dyslexia. However, experimental data verifying this hypothesis is still missing. During our talk, we will present results from our study in which we tested the neural noise hypothesis in dyslexia in adolescents and young adults (aged 15-24) using two methods. First, a direct measure of neurotransmitters’ concentrations in the course of reading words (i.e. functional magnetic resonance spectroscopy, fMRS) and second, an indirect indicator of excitatory to inhibitory neurotransmitters’ ratio (i.e. 1/f signal from EEG power spectrum). 

Funding:  This study was funded by the Polish National Science Center OPUS grant (2019/35/B/HS6/01763) awarded to Katarzyna Jednoróg.