Clarification of the events and baseline

Four events of interest and baseline windows

TFR data

http://dl.dropbox.com/u/14828654/motionMEG/doc/manuscript/figs.xls
http://dl.dropbox.com/u/14828654/motionMEG/doc/manuscript/ROI_memo_combo.xls
http://dl.dropbox.com/u/14828654/motionMEG/doc/manuscript/ROI_TFR_compare.xls
http://dl.dropbox.com/u/14828654/motionMEG/doc/manuscript/ROI_TFR.xls

Download ROIs TFR figs （Updated 2011-01-04）

L_ACC/medial frontal G.

Cohen, M. X., K. R. Ridderinkhof, et al. (2008). "Medial frontal cortex and response conflict: Evidence from human intracranial EEG and medial frontal cortex lesion." Brain Research 1238: 127-142.

stimulus on at 0 s, GO cue at 2.2 s,

speed change onset at somewhere around 1 s

key pressed at 0 s

Peri-response, we also observed enhancements in lower band power(delta) following the desynchronization in the beta band. The pre-response beta and post-response theta changes look related to each other -- need to statistically verify this.

L_SMC

Beta oscillation suppressions around motor and supplementary motor regions have been linked to motor preparatory processes (Miller et al., 2007; Neuper et al., 2006; Pfurtscheller et al., 2003) and are thought to reflect decreased global neural coherence during the processing and planning of movements. 

L_SMC

Beta band power difference in preCun pre-stimulu

Free surfer notes

http://surfer.nmr.mgh.harvard.edu/fswiki/FreeSurferBeginnersGuide

Basics neuronal dynamics

Climesh review on bands (2008)

Delta 0-1 Hz: neocortical, and thalamo-cortical networks.  Large-scale cortical integration.

Theta: subcortical and thalamo-cortical source, involved in a variety of cognitive functions (Hipo theta).

Alpha 8 - 13 Hz: amplitude is related to the level of cortical activation, strong alpha associated with coritcal & behavioural deactivation or inhibition; otherwise (1) highly specific perceptual, attentional, and memory processes.

Beta:
cortically generated (Gross 2004 reported a large scale beta too), b/c of local strictness.  Mainly associated with motor, ERD before/during movement, rebound after the movement stopped.
Attention and higher cognitive functions.

Gamma:
cortically generated too (from intrinsic membrane properties of interneurons or from neocortical exitatory-inhibitory circuits)
* binding
* more recent --> human gamma frequency were reported for encoding, retention and retrieval of info independent of sensory modality.
Problem: small amplitude, similarity to muscle activity leaks into the sensors.



During cognitive efforts: * delta, theta, gamma ERS (pp. 3)
During cognitive processing: * alpha, beta ERD



Super-fast processes (a few ms level), i.e. Buzsaki and Draguhn, 2004; Dragoi and Buzsaki, 2006; Siapas et al., 2005



Varela et al., 2001 review on Phase synchronization


Phase synchronization

(1) Phase coupling over distance (phase-coherence)
(Nunez et al., 1997, 1999; or Rappelsberger, 1998)

• pp 5, widespread coherence in gamma& alpha bands in conscious perception vs unpercepted stim (Rodriguez et al., 1999; Klopp et al., 2000; Mima et al., 2001).
• pp 7,  (Sauseng et al., 2007a) midline theta, increased with task-demand (power diff independent of novelty), in line with literature on sustained attention, localized into ACC, cingulate motor area.   But long range fronto-parietal theta phase coherence was stronger in the novel condition.

(2) Phase synchronization acrossing different frequency (bi-coherence)

• Network of diff size are supposed to oscillate at diff speed
• High temporal preciseness of synch btw oscillations of diff freq can potentially explain how info btw mem sys can be exchanged in cortex。

• instantaneous phase of a slower oscillation modulates the amplitude of a higher freq (Lakatos et al., 2005). delta --> theta, theta --> gamma, hierarchical organization.
• in humans, theta --> gamma (Mormann et al., 2005; Demiralp et al., 2007a,b; Canolty et al., 2006).
• theta --> alpha interact in combined working and long-term memo (Sauseng et al., 2002, theta from anterior to posterior during memo retrieval attempts. When visual items retrieved, the direction of theta reversed. At this theta reversal, upper alpha power decrease -- indicating successful retrieval)
• Methods: Cross-freq phase synchronization (bi-coherence) - Schack: momory-load dependent increase of pase coupling btw prefrontal theta and posterior alpha.  Interpretation: prefrontal theta -> executive processes of working-memo, posterior alpha --> reactivated long-term memo traces (Ruchkin 2003) - thus, working and long-term memo interfacing (Schack 2005)
• Sauseng (2008) theta-gamma coherence in pareital modulated by short-term memory load

(3) Phase-locking after stim presentation

• Look up: 
• Basar, E., 1999a. Brain Function and Oscillations I: Principles and Approaches. Springer, Berlin.
• Basar, E., 1999b. Brain Functions and Oscillations, II: Integrative Brain Functions.Springer, Berlin.
  

• pp 9, there are still ongoing debates over phase resetting or the classical evoked model, and Sauseng (2007b) these two cannot be dessociated <-- should take a look at this paper
• Pase-locking index, Gruber 2005, Schack & Klimesch 2002
  

Event-related changes

Journal club presentation 1

Pfurtscheller Handbook page 7
(1) Evoked response: time-locked & Phase-locked, which could be found from simple averaging. It's the response of a stationary system to the external stimulus.
(2) Induced response: time-locked but NOT phase-locked, can only be extracted through non-linear methods (e.g. envelope detection or power spectral analysis). It could be understood as a change in the ongoing activity, resulting from the changes in the functional connectivity within the cortex.Various factors: may depend on modulating influence arising from neurochemical brain systems, on changes in the strength of synaptic interactions or on changes affecting the intrinsic membrane properties of local neurons.

functional meaning, Pfurtcheller handbook chapter 
Pfurtscheller's ERD during visual processing
Pfurtscheller's basic principles on ERD/ERS ◄═ important paper









Thomas F. Collura 
President of the International Society for Neurofeedback and Research (ISNR).
lecture： Foundations of Neuronal Dynamics & Z Scores 

100ms perception
200ms awareness
300ms differentiate
400ms detection

signal 60-70 ms reaches thalamus, then 100 to occipital, visual alpha: 10 Hz when resting or there is no visual stimulus

delta: 1-4 Hz

Theta: 4-7 Hz

alpha: 7 -15 Hz
high alpha or low beta SMR in SMC: 14 Hz, a very healthy, vigilant state, no body movement (physical relaxation), in SMC typical thalamo-cortical speed is 80 ms in resting, faster than the visual system.  (part 11 in the talk)

beta: 15 - 20 Hz more localized (memory recall), wax and wane, sinusoidal

high beta: 20 - 30 ms, thinking, intensive thinking, worrying, math, wax and waning

gamma: 40 Hz and above
*indicate sensory binding, perceptual binding (association)  high gamma synchrony in meditation experts, and clairvoyant subjects.  R. Davidson lab. 
* Gamma nested in theta

Lenox

re: HBM abstract

Abstract Final [Download]
TFR figs [Download]
A overview of all the ROIs' TFR: [Download]
2010 Frontal lobe poster:  [Download]

http://dl.dropbox.com/u/14828654/motionMEG/doc/201106_HBMO/ROI_TFR_compare.xls
http://dl.dropbox.com/u/14828654/motionMEG/doc/201106_HBMO/ROI_TFR.xls







I am planning to report the underlined results in the abstract, and currently looking up literature for explanation to the data.

Event A:

• fronto-parietal region had higher prestimulus alpha band power for correct trials.
• L_PM_BA9 showed less power change in lower band and beta band.

Support:
[1] Min & Herrmann (2007) tasks required the inhibition of the task-irrelevant feature. Found significantly higher prestimulus total alpha activity (at Pz) in the shape task than the color task. ==> top-down processing prior to stimulation would be reflected in the prestimulus ongoing alpha activity.
[2] Min (2008)  found significantly higher prestimulus alpha activity ==> constant inter-trial interval condition yielded significantly shorter reaction times than variable interval ==> indicating more efficient preparation for upcoming stimuli during the constant ISI.

But, Ergenoglu (2004) and Hanslmayr(2007) found opposite result, higher alpha power in non-perceiver in Pz, Oz.

Event B:

• left premotor BA9 and IPL both had higher high-beta band synchronization (0 - 0.2 s) in error trials. 
• L_IPL and L_SMC both showed a higher alpha synchronization around 0.3 - 0.4s in the error trials
• possibly the left insula played a role here too.
• Error trials had more alpha power increase in the fronto-parietal region after the speed change.  

Event A002: 

• correct trials had higher low-band (delta&theta) power increase and more beta desychronization in left SMC before and after the GO cue.

Event C:

• more alpha band power increase prior to the key onset in error trials. Left IFG gamma band showed interesting pattern, but did not have a very good statistical result.

-- I feel the abstract might look a little too busy if I include everything underlined above, what do you think?

Min, B.-K. and C. S. Herrmann (2007). "Prestimulus EEG alpha activity reflects prestimulus top-down processing." Neuroscience letters 422(2): 131-135.
    In order to test the hypothesis that prestimulus alpha activity reflects top-down inhibitory processing, EEG was recorded from 16 subjects performing a color and a shape discrimination task. Both tasks required the inhibition of the task-irrelevant feature. Longer reaction times and P3 latencies showed that the shape task was more difficult than the color task. We suppose that these different task-difficulties are due to a higher salience of the color feature as compared to the shape feature. Interestingly, we observed significantly higher prestimulus total alpha activity in the shape task than the color task. We concluded that the inhibition of the more salient color feature in the shape task resulted in enhanced prestimulus alpha activity. Such a relationship between prestimulus alpha and poststimulus performance implies that prestimulus alpha reflects prestimulus top-down processing for preparing subsequent task-performance. Since we observed the [`]task' effect of prestimulus alpha activity also in reaction times and in P3 latencies, prestimulus alpha seems to predict such poststimulus responses. Consequently, prestimulus ongoing alpha activity probably reflects top-down information and modulates subsequent poststimulus responses.

Min, B.-K., J. Y. Park, et al. (2008). "Prestimulus EEG alpha activity reflects temporal expectancy." Neuroscience letters 438(3): 270-274.
    Since prestimulus EEG alpha activity has recently been considered to convey prestimulus top-down processing, we investigated whether prestimulus alpha activity reflects temporal expectancy of upcoming stimulation even under the non-classical contingent negative variation (CNV) paradigm. EEG was recorded from 16 subjects performing a color and a shape discrimination task manipulated with constant and variable inter-stimulus interval (ISI) conditions. The power of oscillatory activity was investigated by convolving the EEG signals with Morlet wavelets. The constant ISI condition yielded significantly shorter reaction times than the variable ISI condition, indicating more efficient preparation for upcoming stimuli during the constant ISI. We found significantly higher prestimulus alpha activity in the constant ISI condition than in the variable ISI condition, but no significant CNV even in the constant ISI condition. Such a reflection of temporal expectancy in the prestimulus alpha activity corroborates that the prestimulus top-down mental state for preparing upcoming task-performance is considerably reflected in the prestimulus ongoing alpha activity.









Ergenoglu, T., T. Demiralp, et al. (2004). "Alpha rhythm of the EEG modulates visual detection performance in humans." Cognitive Brain Research 20(3): 376-383.
    The effects of the changes in the frequency spectrum of the electroencephalogram (EEG) on the perception of near-threshold visual stimuli and on the event-related potentials (ERPs) produced by these stimuli were investigated on 12 healthy volunteers. The stimulus intensity, at which each subject could detect 50% of the presented stimuli, was defined as the sensory threshold for that subject. Single ERP trials were separated into two groups: trials with detected and undetected stimuli. The ERPs and the average power spectra of the 1 s prestimulus periods were computed for both conditions. P300 amplitudes of the ERPs, and total power and relative band powers of the delta (0.5-4 Hz), theta (4-7.5 Hz), alpha (7.5-13 Hz), beta (13-30 Hz), and gamma (30-70 Hz) frequency bands of the prestimulus power spectra were measured. Between the two conditions, a specific difference was observed in the relative power of the alpha band, which was significantly lower before detected stimuli (p<0.01) in line with significantly higher amplitudes of the ERPs (p<0.001). These results show that short-lasting changes in brain's excitability state are reflected the relative alpha power of the EEG, which may explain significant variability in perceptual processes and ERP generation especially at boundary conditions such as sensory threshold.
 

Hanslmayr, S., A. Aslan, et al. (2007). "Prestimulus oscillations predict visual perception performance between and within subjects." NeuroImage 37(4): 1465-1473.
    In the present study, the electrophysiological correlates of perceiving shortly presented visual stimuli are examined. In particular, we investigated the differences in the prestimulus EEG between subjects who were able to discriminate between four shortly presented stimuli (Perceivers) and subjects who were not (Non-Perceivers). Additionally, we investigated the differences between the subjects perceived and unperceived trials. The results show that Perceivers exhibited lower prestimulus alpha power than Non-Perceivers. Analysis of the prestimulus EEG between perceived and unperceived trials revealed that the perception of a stimulus is related to low phase coupling in the alpha frequency range (8-12 Hz) and high phase coupling in the beta and gamma frequency range (20-45 Hz). Single trial analyses showed that perception performance can be predicted by phase coupling in the alpha, beta and gamma frequency range. The findings indicate that synchronous oscillations in the alpha frequency band inhibit the perception of shortly presented stimuli whereas synchrony in higher frequency ranges (> 20 Hz) enhances visual perception. We conclude that alpha, beta and gamma oscillations indicate the attentional state of a subject and thus are able to predict perception performance on a single trial basis.