The N170 as a marker of Reading Proficiency Inaugural-Dissertation in der Fakultät Humanwissenschaft der Otto-Friedrich-Universität Bamberg Vorgelegt von Ulrike Kagel aus Parchim Bamberg, den 20.11.2019 Tag der mündlichen Prüfung: 25.04.2020 Dekan: Universitätsprofessor Dr. Jörg Wolstein. Erstgutachter: Universitätsprofessor Dr. Jascha Rüsseler Zweitgutachter: Universitätsprofessor Dr. Claus-Christian Carbon URN: urn:nbn:de:bvb:473-irb-488426 DOI: https://doi.org/10.20378/irb-48842 Dieses Werk ist als freie Onlineversion über das Forschungsinformationssystem (FIS; https://fis.uni-bamberg.de) der Universität Bamberg erreichbar. Das Werk steht unter der CC-Lizenz CC-BY. Dedication I thank My family, who supported me all my life, Dr. Klaus Kagel, who inspired me, and Dr. C. Hoffmann, I also thank Prof. Dr. Jascha Rüsseler for his support. i Contents Dedication .............................................................................................................................. i 1 Introduction ........................................................................................................... 5 1.1 Overview of language-related event-related potentials (ERPs) .............................. 5 The N170 – A Marker for Reading Proficiency? ............................................... 8 2.1 Definition ................................................................................................................ 8 2.2 Sources of the N170 Signal .................................................................................... 9 2.2.1 The N170 and Word Specificity ........................................................................... 10 2.2.2 Studies of Fast vs. Slow Readers .......................................................................... 13 3 Other ERP-Markers for Reading Problems .................................................... 14 3.1 The Mismatch Negativity (MMN) ........................................................................ 14 3.1.1 What does the MMN reflect? ................................................................................ 14 3.1.2 Is the MMN a possible marker for reading problems? ......................................... 16 3.2 The P200 Component ........................................................................................... 23 3.2.1 What does the P200 reflect? ................................................................................. 23 3.2.2 Why is this component a possible biological marker for reading problems? ....... 24 3.3 The N200 Component – Two Kinds ..................................................................... 25 3.3.1 What does the N200 reflect? ................................................................................. 25 3.3.2 Is the N200 a possible marker for reading problems? .......................................... 26 3.4 The P300 component ............................................................................................ 28 3.4.1 What does the P300 reflect? ................................................................................. 28 3.4.2 Is the P300 a possible marker for reading problems? ........................................... 30 3.5 The N400 component ............................................................................................ 32 3.5.1 What does the N400 reflect? ................................................................................. 32 3.5.2 Is the N400 a possible marker for reading problems? .......................................... 32 3.6 The N450 component ............................................................................................ 36 3.6.1 A short excursion: A Component that shows Differences between Rhyming and Non-Rhyming Stimuli .......................................................................................... 36 The Present Studies ............................................................................................ 37 4.1 Background ........................................................................................................... 37 4.1.1 Habituation of the N170 ....................................................................................... 37 4.2 Experiment 1: The Habituation of the N170 in Adults ......................................... 38 4.3 Experiment 2: The Habituation of the N170 in Children ..................................... 50 4.4 Experiment 3: A Test of the Phonological Mapping Hypothesis ......................... 57 4.4.2 Method .................................................................................................................. 62 4.4.3 General Discussion .............................................................................................. 86 4.4.4 Conclusion ............................................................................................................ 88 iii Appendix .............................................................................................................. 90 5.1 Study 1 (N170-Adults) .......................................................................................... 90 5.2 Study 2 (N170-Children) ...................................................................................... 91 5.3 Study 3 .................................................................................................................. 92 References ............................................................................................................ 98 iv 1 Introduction The major aim of the thesis is to investigate a new biological marker for reading proficiency. One typical marker for dyslexia is the mismatch negativity (MMN) of the auditory event-related brain potential. In the present studies I shall explore a marker that is more reading-specific: the N170 component (also called N1). This component is more reading specific because it responds to and is modulated by visual stimuli depending on the expertise of the reader with a specific stimulus class such as words or faces. In contrast, the MMN is primarily sensitive to deviant auditory stimuli in an otherwise consistent series of auditory events. The first two studies examined whether there is a correlation between habituation of the N170 and reading speed in adult normal readers and 2nd graders. The ongoing habituation of the N170 signal represents the automatization of the reading process. In a third study rhymes were used to explore the relation between N170 laterality, phonological abilities (rhyming) and reading ability/speed. 1.1 Overview of language-related event-related potentials (ERPs) Visual stimuli like faces, pictures of objects and words elicit the N170 component after 150 ms to 200 ms in temporo-parietal regions while real visual objects rather activate temporal- occipital regions. The N170 is investigated in order to analyze a print-specific ERP. Other typical language-related components also appear depending on the task. The MMN appears around 100-200 ms post-stimulus and is an auditory evoked potential that is thought to be a good candidate as a biomarker for reading difficulties (see Section 3.1). I will review research on the early left anterior negativity (ELAN) which basically represents automatized processing of syntactic structure (parsing) (Hahne & Friederici, 1999). I will also review research on the P200 component that peaks at about 150 – 275 ms and which is investigated primarily in the auditory domain. The N400 reflects the processing of semantic information while the P300 reveals insights in tasks that require an intentional discrimination response (see Figure 1 and Figure 2). 5 Figure 1: A schematic overview of some language-related potentials. In the next sections the different language-associated ERPs and their relation to dyslexia or specific language impairment (SLI) are reviewed. 6 Latency in ms Figure 2: Spatial-chronologically organization of the auditory sentence processing. On the right side of the time line the sentence processing model of Angela Friederici (Friederici, 2002) is depicted. On the left side, other language related ERPs and their function are summarized in regards to the time line. Figure adapted from Jäncke (2013), Lehrbuch Kognitive Neurowissenschaften, p.637. 7 2 The N170 – A Marker for Reading Proficiency? 2.1 Definition The N170 is a negative deflection of the event-related brain potential that is elicited by visual stimuli at temporo-parietal electrodes with a maximum amplitude 150-200 ms post-stimulus. It is evoked by visual stimuli in general and is prone to the expertise of the observer. The N170 amplitude was found to be larger, if experts were looking at stimuli that were more familiar to them than others. That means, as an example, that the N170 evoked by pictures of animals is higher for animal experts vs. non-experts (Tanaka & Curran, 2001) and can be modulated, to take an example from another study, by the expertise of car-experts (Gauthier, Curran, Curby, & Collins, 2003). The present doctoral thesis addresses the N170 component that is elicited by words or letters, i.e. it is sensitive to the tuning for print and visual print expertise. 8 2.2 Sources of the N170 Signal ERP and magnetoencephalographic (MEG) data of Tarkiainen et al (1999) and in the study by Maurer et al (2005b) found that there is print-specific activation in parts of the occipito- temporal cortex. FMRI data support this hypothesis and found sensitivity to word-like stimuli in the fusiform gyrus – the so-called visual word form area (VWFA). Figure