P10 04/06/11 1 SPAN Harry Howard - Tulane University

LA NEUROSINTAXIS 11 ABR 2011 – DÍA 36 Neurolingüística del español SPAN 4270 Harry Howard Tulane University

ORGANIZACIÓN DEL CURSO Neurospan/ El curso es apto para un electivo en neurociencia. Neurolinguistics and linguistic aphasiology está en reserva en la biblioteca. Human Research Protection Program Before beginning research at Tulane University, all research personnel must complete the CITI Training Program; this can be completed at 04/06/11 3 SPAN Harry Howard - Tulane University

REPASO Ha sido la prueba. 04/06/11 SPAN Harry Howard - Tulane University 4

NEUROSINTAXIS 04/06/11 5 SPAN Harry Howard - Tulane University

EEG Electroencephalography (EEG) is the measurement of electrical activity produced by the brain as recorded from electrodes placed on the scalp. 04/06/11 SPAN Harry Howard - Tulane University 6

SCALP (CUERO CABELLUDO) EEG Scalp EEG is collected from tens to hundreds of electrodes positioned on different locations at the surface of the head. EEG signals (in the range of millivolts) are amplified and digitalized for later processing. 04/06/11 SPAN Harry Howard - Tulane University 7

ERP (POTENCIA EVOCADA) Event-related brain potentials (ERPs) are positive and negative voltage fluctuations (or components) in the ongoing EEG that are time-locked to the onset of a sensory, motor, or cognitive event. ERPs reflect brain activity that is specifically related to some stimulus or other event. This activity cannot be directly observed in the EEG the EEG is a composite of simultaneously occurring brain activity it doesn't reflect just the activity associated with the event of interest In other words, the "signal" (the brain response to some event) is swamped by the "noise" (the brain activity that is unrelated to that event). 04/06/11 8 SPAN Harry Howard - Tulane University

SIGNAL AVERAGING The solution to this problem is to present not just one instance of the event of interest, but many instances. Epochs of brain activity, each one time-locked to the onset of an event, are then averaged together. The "random" activity washes out during averaging, whereas the brain activity of interest - namely, what is constant over presentations of the event of interest - stays in the signal. Through this signal-averaging procedure, it is possible to isolate the brain response that is specifically elicited in response to some event of interest. 04/06/11 9 SPAN Harry Howard - Tulane University

ERP PROCEDURE 04/06/11 10 SPAN Harry Howard - Tulane University

ERP COMPONENTS NAMED BY THEIR POLARITY AND PEAK LATENCY (IN MS) 04/06/11 11 SPAN Harry Howard - Tulane University

INVERSE SOLUTION Ideally, one would like to identify the precise neural sources that generate the ERPs (known as the "inverse solution"). Unfortunately, the inverse solution is impossible to compute with certainty, because any given scalp distribution could, in principle, be generated by any number of source configurations within the brain. However, researchers have developed powerful tools that provide good estimates of these neural sources, given some reasonable assumptions. 04/06/11 12 SPAN Harry Howard - Tulane University

LORETA One such method is known as "LORETA", which provides an estimate of the current distribution throughout the entire 3- dimensional space within the brain. An example of a LORETA solution, mapped onto a normalized brain space, is provided below. 04/06/11 SPAN Harry Howard - Tulane University 13

THE LINGUISTIC ERPS Friederici (2002) 04/06/11 14 SPAN Harry Howard - Tulane University

NEUROCOGNITIVE MODEL OF AUDITORY SENTENCE PROCESSING 04/06/11 15 SPAN Harry Howard - Tulane University

PHASES OF AUDITORY SENTENCE PROCESSING The temporal scale along the bottom comes from ERP (and MEG) studies, which Friederici divides into three main phases, initiated by a ‘zeroth’ phase of phonological processing: N100: phase 0, phonological processing ELAN (early left anterior negativity): phase 1, syntactic structure building N400/LAN: phase 2, establish semantic relations P600: phase 3, syntactic repair 04/06/11 16 SPAN Harry Howard - Tulane University

B RODMANN AREAS IN THE LEFT HEMISPHERE 04/06/11 17 SPAN Harry Howard - Tulane University Inferior frontal gyrus (IFG) = green, Superior temporal gyrus (STG) = red Middle temporal gyrus (MTG) = blue

T HE ELAN Early left anterior negativity 04/06/11 18 SPAN Harry Howard - Tulane University

INTRODUCTION The first phase ( ms) represents the time window in which the initial syntactic structure is formed on the basis of information about word category. For instance, the insertion of a contracted preposition+article between an auxiliary verb and past participle in German, produces a significantly higher ERP amplitude during this period than the same sentence without the intrusive material Die Gans wurde (*im) gefüttert. The goose was (*in the) fed. 04/06/11 19 SPAN Harry Howard - Tulane University

PHRASES CAN BE PUT TOGETHER TO FORM SENTENCES Striped orange cats slept soundly. Colorless green ideas slept furiously. 04/06/11 20 SPAN Harry Howard - Tulane University

SINCE THE MEANING DOESN’T MATTER, WE CAN WRITE WORD-ORDER RULES BASED ON CATEGORIES A noun phrase (NP) consists of … ? An optional determiner followed by one or more adjectives followed by a noun NP  (Det) Adj (Adj) N A verb phrase (VP) consists of … ? A verb followed by an adverb VP  V Adv A sentence consists of … ? A noun phrase followed by a verb phrase S  NP VP 04/06/11 21 SPAN Harry Howard - Tulane University

BUT SUCH A REAL GRAMMAR IS FAIRLY COMPLEX Perhaps too complex for direct study They can teach subjects a simplified set of rules from a language that they do not know. But even better is to teach subjects an artificial grammar (the syntactic analog of a nonsense word) which have easy-to-control properties. 04/06/11 22 SPAN Harry Howard - Tulane University

A REGULAR GRAMMAR The rules S  Xab X  Xab X  ab How would you generate the string “ababab”? This language is known as (ab)n. From fMRI we know that violations of this grammar activate BA 44 and BA 6. The English grammar that we made up is also of this type. So are the violations of German grammar. 04/06/11 23 SPAN Harry Howard - Tulane University

A CONTEXT-FREE GRAMMAR The rules S  aXb X  aXb X  ab How would you generate the string “aaabbb”? How would you generate the string “ababab”? This language is known as a n b n. From fMRI we know that violations of this grammar activate BA 44, but not BA 6. 04/06/11 24 SPAN Harry Howard - Tulane University

EL PRÓXIMO DÍA Más neurosintaxis 04/06/11 25 SPAN Harry Howard - Tulane University