Liina Pylkkänen Department of Linguistics/ Center for Neuromagnetism New York University

1. LP, Aug 03, Tateshina MEG, the Mental Lexicon and Morphology Liina Pylkkänen Department of Linguistics/ Center for Neuromagnetism New York University

2. LP, Aug 03, Tateshina MEG, the Mental Lexicon and Morphology Day 1 Lexical access 1: The M350 as an MEG index of lexical activation Day 2 Lexical access 2: The M350 and mechanisms of recognition Day 3 Morphology 1: The M350 as a tool for investigating similarity and identity Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology

3. LP, Aug 03, Tateshina Acknowledgements (the yellow people have kindly allowed me to use their slides in these presentations) • Alec Marantz (MIT) • Andrew Stringfellow (UCSD) • Laura Gonnerman (Lehigh University) • Martin Hackl (Pomona College) • David Embick (University of Pennsylvania) • Meltem Kelepir (Eastern Mediterranean University) • Jeanette Schaeffer (Ben Gurion University) • Elissa Flagg ( U Toronto) • Linnaea Stockall (MIT) • Sophie Feintuch (Portsmouth High School, NH) • Emily Hopkins (Portsmouth High School, NH) • Eytan Zweig (NYU) • Machteld van Rijsingen (NYU/ University of Amsterdam) • Tony Wilson (University of Minnesota) • Colin Phillips (University of Maryland, College Park) • Robert Fiorentino (University of Maryland, College Park) • David Poeppel (University of Maryland, College Park)

4. LP, Aug 03, Tateshina Day 1 Lexical access 1: The M350 as an MEG index of lexical activation • General remarks on methodology and methodological challenges in cognitive neuroscience. • Basic lexical access experiments (frequency, repetition priming): M350. • Modality question. • More detail on the nature of frequency effects. • Pinpointing the cognitive level of the M350. Initial activation of the lexicon. • Is this result compatible with evidence from other techniques? Eye-tracking, masked priming.

5. LP, Aug 03, Tateshina Day 1 Lexical access 1: The M350 as an MEG index of lexical activation • General remarks on methodology and methodological challenges in cognitive neuroscience. • Basic lexical access experiments (frequency, repetition priming): M350. • Modality question. • More detail on the nature of frequency effects. • Pinpointing the cognitive level of the M350. Initial activation of the lexicon. • Is this result compatible with evidence from other techniques? Eye-tracking, masked priming.

6. 1. Use knowledge of language to isolate neural correlates of linguistic processes Linguistic theory Psycholinguistics 2. Use neural correlates of linguistic processes as additional dependent variables in the study of language LP, Aug 03, Tateshina

7. LP, Aug 03, Tateshina How to isolate neural correlates of linguistic processes? Method 1 • Conditions differ in computational demands of linguistic function A. Method 2 • Conditions differ in presence of linguistic function A. • Stim 1: Stim 2: • +lexical access - lexical access Intuitively: • CAT KPT • or, often: • Task 1: Task 2: • Semantic decision Phonological decision Stim 1: Stim 2: CAT CLAM Frequent Infrequent Fast lexical access Slow lexical access • Task is constant so reaction times can serve as behavioral index of manipulation • If the task changes there can be no behavioral index of the manipulation. • Need model of cognitive functions involved.

8. LP, Aug 03, Tateshina How to isolate neural correlates of linguistic processes? Method 1 • Conditions differ in computational demands of linguistic function A. • Same neural sources but different timing and/or magnitude Method 2 • Conditions differ in presence of linguistic function A. • (possibly) different sources

9. LP, Aug 03, Tateshina Why lexical access? • Part of virtually all linguistic processing. • 1st processing stage that is potentially modality independent, and “linguistic”, in a narrow sense of the word. • Different theories about linguistic processing and representation make contrasting predictions about lexical access •  Neural correlate of lexical access a valuable additional dependent measure to behavioral processing measures.

10. What affects lexical access? What brain activity is affected by those factors? LP, Aug 03, Tateshina Linguistic theory Psycholinguistics

11. Response CAT 0 200 400 600 800 1000 Time [msec] LP, Aug 03, Tateshina • Lexical decision times are affected by: • Lexical frequency • Semantic, phonological, morphological relatedness • Etc. • But trying to infer the cognitive level of these effects from reaction times alone is complicated. • Electrophysiological data adds a dependent measure for every millisecond:

12. Response CAT 0 200 400 600 800 1000 Time [msec] LP, Aug 03, Tateshina • But identifying the activity affected by any one stimulus property is not particularly informative in of itself. • Need to show that some natural class of stimulus variables all affect the same neural activity, where “natural class” is defined by the predictions of a cognitive model.

13. LP, Aug 03, Tateshina Assumptions/hypotheses that drive, and are tested by, the present research • Representation: • There is a modality independent lexicon. • Lexical entries connect sound and meaning – single lexicon. • All word formation is syntactic. • Processing: • Timing of lexical access depends on the activation level of lexical entries at stimulus presentation. • The activation level of lexical entries depends on • Frequency • Preceding context (priming) • Phonological and semantic relatedness should affect the same neural activity. NB: All of these assumptions are more or less controversial so we’ll continually keep evaluating how they succeed in explaining the data.

14. LP, Aug 03, Tateshina Magnetoencephalography (MEG) EEG http://www.ctf.com/Pages/page33.html

15. LP, Aug 03, Tateshina Magnetoencephalography (MEG) EEG MEG http://www.ctf.com/Pages/page33.html

16. LP, Aug 03, Tateshina MEG vs. EEG Source: http://www.allgpsy.unizh.ch/graduate/mat/180102/Lecture1.pdf

17. LP, Aug 03, Tateshina Right-hand rule Source: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html#c1

18. Outgoing Ingoing LP, Aug 03, Tateshina Magnetoencephalography (MEG) Distribution of magnetic field at 93 ms (auditory M100) Averaged epoch of activity in all sensors overlain on each other.

19. LP, Aug 03, Tateshina Magnetoencephalography (MEG)

20. LP, Aug 03, Tateshina Day 1 Lexical access 1: The M350 as an MEG index of lexical activation • General remarks on methodology and methodological challenges in cognitive neuroscience. • Basic lexical access experiments (frequency, repetition priming): M350. • Modality question. • More detail on the nature of frequency effects. • Pinpointing the cognitive level of the M350. Initial activation of the lexicon. • Is this result compatible with evidence from other techniques? Eye-tracking, masked priming.

21. An MEG Study of Word Frequency Effects in Lexical Decision M. Hackl1, D. Embick1,2, J. Schaeffer3, M. Kelepir1, A. Marantz1,2 1 Dept. of Linguistics and Philosophy, MIT 2 JST/MIT [Mind Articulation] Project 3Dept. of Linguistics, Ben-Gurion University of the Negev

22. The frequency effect • Lexical decisions to frequent words faster than decisions to infrequent words. • Account in activation-based models: frequent words have a higher “resting” level.

23. Objective:Identification of an MEG component whose latency varies with the frequency of words, to be used as an index in further studies of lexical access and lexical organization. Primary Result:A component in the response to words at 350ms, m350, varies in latency with the frequency of words.

24. Stimuli: • Six bins of open-class words, arranged according to frequency; Cobuild corpus, 320 million words Category n/Million Log Freq. Example 64 700 2.8 number 65 140 2.1 ask 66 30 1.4 wheel 67 6 .7 candle 68 1 0 clam 69 .2 -.7 snarl • Two classes of non-words, pronounceable and • non-pronounceable; ratio of words:non-words 1:1.

25. Task: Lexical Decision. Subjects:n = 9; 5F, 4M; right-handed native speakers of English. Analysis:Peaks identified based on RMS analysis. A subset of 17 left-hemisphere sensors were used for identification of peaks; this set was held constant across subjects/conditions.

27. Three primary components m170

28. 170msec 250msec 350msec RMS analysis 2. 3. 1. LP, Aug 03, Tateshina M170 M250 M350 CAT 0 200 300 400 Time [msec]

30. Two Distinct Components • Latency of m350 response varies by log frequency of words • (p < .0001) • Latency of m250 response does not vary with log frequency • (p = .8)

31. Magnetic Field and Contour Map: High Frequency

32. Magnetic Field and Contour Map: Low Frequency

33. The M350 • Is the first MEG component serving as a predictor of the behavioral frequency effect. • If the M350 indexes lexical access, it is also predicted to show priming effects.

34. A neural response sensitive to repetition L. Pylkkänen1,2, E, Flagg1, A. Stringfellow2, A. Marantz1,2 1 Dept. of Linguistics and Philosophy, MIT 2 JST/MIT [Mind Articulation] Project

35. The repetition priming effect • Words are responded to more quickly on their second presentation than on their first. • After a word has been accessed, its activation slowly returns to resting level – if the word is presented again while there is still residual activation, access is facilitated.

36. Objective:Identification of an MEG component whose latency predicts the behavioral repetition priming effect. Result:A component in the response to words and pronouceable nonwords at 350ms, M350, occurs earlier for repeated than for nonrepeated words.

37. Stimuli • 2 x 2 design with repetition and target lexicality as factors. • Timing: + DOG Prime, 500 ms 500 ms DOG Target, real word or not?

38. Analysis • Only correct trials were analyzed. • RMS from a minimum of 17 left hemisphere sensors showing large responses between 150 and 450 ms. • The latencies and amplitudes of major RMS peaks were recorded using latency and magnetic field distribution as criteria for determining whether a peak belonged to a certain category of responses.

39. Effect of repetition on the M350 and RT * * n.s n.s

40. M350 positive signal maximum for repeated and for nonrepeated words (single subject data)

41. 170 msec 250 msec 350 msec Sagittal view A P auditory M100 M350 LP, Aug 03, Tateshina CAT 0 200 300 400 Time [msec]

42. LP, Aug 03, Tateshina Day 1 Lexical access 1: The M350 as an MEG index of lexical activation • General remarks on methodology and methodological challenges in cognitive neuroscience. • Basic lexical access experiments (frequency, repetition priming): M350. • Modality question. • More detail on the nature of frequency effects. • Pinpointing the cognitive level of the M350. Initial activation of the lexicon. • Is this result compatible with evidence from other techniques? Eye-tracking, masked priming.

43. Modality independent lexical access: MEG evidence from an auditory lexical decision task Linnaea Stockall, Dan Wehner & Alec Marantz Dept. of Linguistics and Philosophy, MIT & KIT/MIT MEG Lab

44. Latency of m350 Component Categories (n/Million): 1: 700 2: 140 3: 30 4: 6 5: 1 6: .2 2 3 4 1 5 6 Frequency Category (Frequent -- Infrequent) Embick et al. (1999) M350 facilitated by high frequency stimuli in visual lexical decision experiment

45. M350: index of initial lexical activation MEG activity elicited by visual words (lexical decision task): • The M350 is sensitive to • Lexical frequency • Repetition • Phonological similarity • Semantic similarity • Sublexical frequency • Morphological Family Size • The M350 is NOT sensitive to interlexical competition M350

46. Question: Do visual word recognition and auditory word recognition involve accessing the same mental lexicon?:

47. Materials & Method Stimuli: • 48 High Frequency words • 48 Low Frequency words • 96 Non Word Fillers • Matched for length, number of syllables and density • Speech recorded in Soundedit and normalized for intensity

48. Materials & Method Subjects: • 10 right handed native English speakers with normal vision gave informed consent to participate in this experiment. RT and MEG data was collected from 6 subjects, RT data only from 4 subjects.

49. Materials & Method Tone Test: • After the frequency experiment, subjects listened to 50 300ms long 1KHz tones.

50. Materials & Method MEG Data collection: • Neuromagnetic fields were recorded using an axial gradiometer whole-head system (Kanazawa Institute of Technology, Kanazawa, Japan). One subject was recorded with a 93 channel system, 3 with a 160 channel system Data were acquired in a band between DC and 200Hz, at a 1000Hz sampling frequency.