ERP, MEG, Neural Oscillations LSA Summer Institute 2019 Electroencephalography: EGG • Functional neuroimaging technique • Measurement of the electrical signals generated from on-going neural activity.

• Generated from neurons, circuits, and populations of neurons, • Slow and fast, fluctuations of electrical activity • Inherent and stimulus driven sources.

• Analyses: • Even Related Potential (ERP) Componentry • Oscillatory Activity -spectral properties (i.e. time-frequency analysis) Electroencephalography:EEG

• Functional neuroimaging technique • Measurement of electrical currents occurring indexing occurring cellular activity of neurons.

• ERP Componentry; Event Related Potential” • Oscillatory Activity -spectral properties (i.e. time-frequency analysis) Magnetoencephalography: MEG

• Functional neuroimaging technique • Measurement of magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers.

• MEG Componentry • Oscillatory Activity -spectral properties (i.e. time-frequency analysis) Raw “EEG” EEG and Brain Waves in the Popular Press Cognitive States Common Classifications

• Delta .1-3Hz ~1 sec. 1Hz • Theta 4-7Hz ~200 msec. 5Hz • Alpha 10-12Hz ~100 msec. 10Hz • Beta 16-21Hz ~50 msec 20Hz • Lo Gamma 40-60Hz ~25 msec 40Hz • Hi Gamma 60-100Hz ~10msec 100Hz Analysis Approaches

• Stimulus Evoked Potentials “ERP”

• Spatial-Temporal Analysis “time-frequency” analysis • Power of oscillatory activity at different frequencies. Even Related Potentials

• Event-related potentials (ERPs) are very small voltages generated in the brain structures in response to specific events or stimuli (Blackwood and Muir, 1990). • They are EEG changes that are time locked to sensory, motor or cognitive events that provide safe and noninvasive approach to study psychophysiological correlates of mental processes. • They are thought to reflect the summed activity of postsynaptic potentials produced when a large number of similarly oriented cortical pyramidal neurons (in the order of thousands or millions) fire in synchrony while processing information (Peterson et al., 1995 ERP Classification

• Exogenous: (onset < 100 msec.) The early waves, or components peaking roughly within the first 100 milliseconds after stimulus, are termed ‘sensory’ or ‘exogenous’ as they depend largely on the physical parameters of the stimulus. • Sensory processing • Early attention • Auditory Brain Stem Response • MMN “Mismatch Negativity” • Wave 5 • Middle Latency Responses • P-1/N1 • Endogenous: (> onset 100msec.) ERPs generated in later parts reflect the manner in which the subject evaluates the stimulus and are termed ‘cognitive’ or ‘endogenous” • Evaluative/Cognitive • Surprise • Violations • N-1, N4 • P2, P3, P6 • ERPs as they examine information processing. The waveforms are described according to latency and amplitude. Where do electrical potentials come from ?

. Event Related Potentials • Time-locked, summed & averaged EEG

EEG from 6 sites EEG states Ascending Auditory Hirearchy Auditory Event Related Potentials

• Auditory P1 is used as a bio-marker for the development of central auditory pathway. • P1 component is associated with the auditory cortex in the superior temporal gyrus EEG

Electroencephalogram Measures on going electrical activity (electrical potentials) Orchestrated firings to an Event

CAT Event Related Potentials • Signal Averaging Event Related Potentials Assumptions

• Linguistic Theory • Syntax and semantic separable and independent • Psycholinguistics • Different operation construct syntactic and semantics forms • Alternative proposals: closer connections between syntax and meaning • Can Neuroscience techniques be used to inform our theories ? Event Related Potentials • Synchronized Activity Populations of Neurons • Well defined temporal and morphological properties of waveforms.

N-400 N-1

Early P-600 Sensory P-200 Past Study

• Evidence of differential ERP indices of linguistic processing

• I like coffee with milk and ______• Semantically plausible: sugar • Semantically implausible: mud • Semantically implausible word elicit a • N-400 • Central-Parietal negative wave

(Kutas and Hillyard, 1980) N-400

N400

+ N-400 Interpretations 1. Semantic Integration: • Semantic integration of the target into the current context. • The more difficult it is to access a lexical item from memory, the more negative the N400 amplitude

2. Lexical Integration • Represents the access of lexical information from long-term semantic memory. The more difficult it is to access a lexical item from memory, the more negative the N400 amplitude .

• The data from across these techniques provide strong evidence that the posterior middle temporal cortex is involved in generating the N400 effect. • ,Supports the claim that the N400 effect is at least to some degree due to facilitated lexical access, and argues against an account in which the effect is purely integrative.

See: Lau, Phillips & , Poeppel (2008) Past Studies

• Syntactic Anomaly • Agreement errors • The cats wont eat • The cats wont eating • Subcategorization • The boy slept • The boy slept the guitar • P-600 • Central-parietal positive • 600 msec. after the anomaly • N-140 • left anterior negativity P-600

P600 LAN (N-140) LAN Common Language-related ERPS (e.g., Osterhout & Nicol, 1999, Friederici 1995, Kluender & Kutas 1993). • N400 N400 • Lexico-semantic difficulty • Negative deflection + • 300-500 ms post-onset

• P600 P600 • Syntactic difficulty • Positive deflection • 500-900 ms post-onset.

• LAN(ELAN) LAN • Automatic parsing • Working memory operations in the service of grammatical processing • Negative deflection • 100-280 ms post-onset. ERP advantages

• Millisecond by millisecond accuracy • Multidimensional • Vary in polarity, timing, morphology & scalp location • Sensitive to neural organization. • Sensitive to cognitive states • Non-invasive

• Disadvantages: • Spatial Resolution: e.g. Inverse Problem • Often requires “artificial” presentation rates.