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Functional Magnetic Resonance Spectroscopy (fMRS) Study on Reading-Related Metabolite Changes
Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 3 and 4
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
Functional Magnetic Resonance Spectroscopy (fMRS) is a non-invasive technique used to measure changes in metabolite concentrations in response to various stimuli. While it is a powerful tool for gaining deeper insights into the mechanisms accompanying brain activations, it remains relatively novel, lacking clear guidelines for optimal data acquisition and analysis. Most existing studies have focused on changes in the visual cortex in response to simple visual stimuli. In our innovative approach, we examine metabolite changes induced by reading-related stimuli within individually localized language-sensitive left superior temporal cortex (STC) and a control region in the medial prefrontal cortex (MPC). Moreover, we extend the investigation by incorporating fMRS data acquisition with varying delays between stimulation and signal acquisition, aiming to study the glutamate response function (500 ms, 1000 ms, 3000 ms, 4500 ms). Fifty-six adolescents and young adults aged 15-24 years (27 females, 29 males) with varying reading levels participated in an fMRS experiment on a 7T GE scanner. Visual stimuli were Polish words and false font strings (written with BACS font). There were 13 stimulation blocks (64 seconds each) containing 12 trials (6 made of words and 6 false fonts in pseudo-random order). Each trial included 3 stimuli presented for 250 ms with 50 ms break in between (850 ms in total). The rests between stimulation blocks varied in duration (between 32 and 36 seconds). Participants were asked to press a button every time when saw a word or a false font string with descending feature. The experiment for single voxel (320 averages with suppressed water and 8 averages with unsuppressed water) took 21minutes 52 seconds. Data were acquired from two regions of interest (voxel size: 15 x 15 x 15 mm³): the MPC and left STC. In the left STC, we observed significant changes relative to baseline in glutamate levels at 500 ms (t = -2.073, p = 0.043), 1000 ms (t = -2.097, p = 0.041), and 4500 ms (t = -2.211, p = 0.032) after stimulus presentation (average for words and false font strings). No such changes were observed in the control MPC region. In conclusion, we found significant changes in glutamate levels following visual stimulation in the left STC, a brain region involved in the reading process, but not in the control MPC region. These findings indicate that the observed changes are specific to the language-sensitive region. Further analysis will explore the temporal dynamics of glutamate changes. fMRS has great potential for investigating the neurobiological processes of reading, and it is essential to continue developing and refining this technique.
Topic Areas: Reading,