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Category: EEG / MEG

Categories
Auditory Speech Processing EEG / MEG Papers Speech

New Review Paper out: Wöst­mann, Fiedler & Obleser in Lan­guage, Cog­ni­tion and Neuroscience

A review arti­cle for those inter­est­ed in how to use mag­ne­to-/elec­troen­cephalog­ra­phy (M/EEG) to study speech com­pre­hen­sion. We pro­vide a his­tor­i­cal­ly informed overview over depen­dent mea­sures in the time and fre­quen­cy domain, high­light recent advances result­ing from these mea­sures and review the noto­ri­ous chal­lenges and solu­tions speech and lan­guage researchers are faced with when study­ing elec­tro­phys­i­o­log­i­cal brain responses.

Now avail­able online:

http://www.tandfonline.com/doi/full/10.1080/23273798.2016.1262051

Abstract

Mag­ne­to- and elec­troen­cephalo­graph­ic (M/EEG) sig­nals record­ed from the human scalp have allowed for sub­stan­tial advances for neur­al mod­els of speech com­pre­hen­sion over the past decades. These meth­ods are cur­rent­ly advanc­ing rapid­ly and con­tin­ue to offer unpar­al­leled insight in the near-to-real-time neur­al dynam­ics of speech pro­cess­ing. We pro­vide a his­tor­i­cal­ly informed overview over depen­dent mea­sures in the time and fre­quen­cy domain and high­light recent advances result­ing from these mea­sures. We dis­cuss the noto­ri­ous chal­lenges (and solu­tions) speech and lan­guage researchers are faced with when study­ing audi­to­ry brain respons­es in M/EEG. We argue that a key to under­stand­ing the neur­al basis of speech com­pre­hen­sion will lie in study­ing inter­ac­tions between the neur­al track­ing of speech and the func­tion­al neur­al net­work dynam­ics. This arti­cle is intend­ed for both, non-experts who want to learn how to use M/EEG to study speech com­pre­hen­sion and schol­ars aim­ing for an overview of state-of-the-art M/EEG analy­sis methods.

Categories
Auditory Cortex Auditory Perception Cross-Modal Integration EEG / MEG Neural Oscillations Perception

New paper out: Plöchl, Gas­ton, Mer­ma­gen, König & Hair­ston, Sci­en­tif­ic Reports

An arti­cle by our new AC group mem­ber Michael Plöchl from his PhD project in Osnabrück has been accept­ed for pub­li­ca­tion in Sci­en­tif­ic Reports. In their study, Plöchl, Gas­ton, Mer­ma­gen, König and Hair­ston demon­strate that “Oscil­la­to­ry activ­i­ty in audi­to­ry cor­tex reflects the per­cep­tu­al lev­el of audio-tac­tile integration”.

oscillatory_activity

Abstract
Cross-modal inter­ac­tions between sen­so­ry chan­nels have been shown to depend on both the spa­tial dis­par­i­ty and the per­cep­tu­al sim­i­lar­i­ty between the pre­sent­ed stim­uli. Here we inves­ti­gate the behav­ioral and neur­al inte­gra­tion of audi­to­ry and tac­tile stim­u­lus pairs at dif­fer­ent lev­els of spa­tial dis­par­i­ty. Addi­tion­al­ly, we mod­u­lat­ed the ampli­tudes of both stim­uli in either a coher­ent or non-coher­ent man­ner. We found that both audi­to­ry and tac­tile local­iza­tion per­for­mance was biased towards the stim­u­lus in the respec­tive oth­er modal­i­ty. This bias lin­ear­ly increas­es with stim­u­lus dis­par­i­ty and is more pro­nounced for coher­ent­ly mod­u­lat­ed stim­u­lus pairs. Analy­ses of elec­troen­cephalo­graph­ic (EEG) activ­i­ty at temporal–cortical sources revealed enhanced event-relat­ed poten­tials (ERPs) as well as decreased alpha and beta pow­er dur­ing bimodal as com­pared to uni­modal stim­u­la­tion. How­ev­er, while the observed ERP dif­fer­ences are sim­i­lar for all stim­u­lus com­bi­na­tions, the extent of oscil­la­to­ry desyn­chro­niza­tion varies with stim­u­lus dis­par­i­ty. More­over, when both stim­uli were sub­jec­tive­ly per­ceived as orig­i­nat­ing from the same direc­tion, the reduc­tion in alpha and beta pow­er was sig­nif­i­cant­ly stronger. These obser­va­tions sug­gest that in the EEG the lev­el of per­cep­tu­al inte­gra­tion is main­ly reflect­ed by changes in ongo­ing oscil­la­to­ry activity.
Categories
Auditory Cortex Auditory Perception Media Neural Oscillations Papers Publications Uncategorized

New fea­turette in eLife: Tell me some­thing I don’t know

For those inter­est­ed in audi­to­ry cor­tex and how a regime of pre­dic­tions, pre­dic­tion updates and sur­prise (a ver­sion of “pre­dic­tion error”) might be imple­ment­ed there, I con­tributed a brief fea­turette (“insight”, they call it) to eLife on a recent paper by Will Sed­ley, Tim Grif­fiths, and oth­ers. Check it out.
Obleser-elife-Figure

[For those not so famil­iar with it, “eLife”, despite its aes­thet­i­cal­ly ques­tion­able name, pos­es an inter­est­ing and rel­a­tive­ly new, high-pro­file, open-access pub­lish­ing effort by nobel-prize-win­ning Randy Schek­man, for­mer SfN pres­i­dent Eve Marder and others.] 
Categories
Auditory Cortex Auditory Neuroscience Auditory Perception Auditory Speech Processing Editorial Notes EEG / MEG Executive Functions Neural Oscillations Neural Phase Papers Publications Speech Uncategorized

[UPDATE] New paper in PNAS: Spa­tiotem­po­ral dynam­ics of audi­to­ry atten­tion syn­chro­nize with speech, Woest­mann et al.

Wöst­mann, Her­rmann, Maess and Obleser demon­strate that the hemi­spher­ic lat­er­al­iza­tion of neur­al alpha oscil­la­tions mea­sured in the mag­ne­toen­cephalo­gram (MEG) syn­chro­nizes with the speech sig­nal and pre­dicts lis­ten­ers’ speech comprehension.

Now avail­able online:

http://www.pnas.org/content/early/2016/03/18/1523357113

Press release:

https://www.uni-luebeck.de/forschung/aktuelles-zur-forschung/aktuelles-zur-forschung/artikel/aufmerksamkeit-in-wellen-erfolgreich-zuhoeren-im-rhythmus-der-sprache.html

spatiotemporal_dynamics

Abstract
Atten­tion plays a fun­da­men­tal role in selec­tive­ly pro­cess­ing stim­uli in our envi­ron­ment despite dis­trac­tion. Spa­tial atten­tion induces increas­ing and decreas­ing pow­er of neur­al alpha oscil­la­tions (8–12 Hz) in brain regions ipsi­lat­er­al and con­tralat­er­al to the locus of atten­tion, respec­tive­ly. This study test­ed whether the hemi­spher­ic lat­er­al­iza­tion of alpha pow­er codes not just the spa­tial loca­tion but also the tem­po­ral struc­ture of the stim­u­lus. Par­tic­i­pants attend­ed to spo­ken dig­its pre­sent­ed to one ear and ignored tight­ly syn­chro­nized dis­tract­ing dig­its pre­sent­ed to the oth­er ear. In the mag­ne­toen­cephalo­gram, spa­tial atten­tion induced lat­er­al­iza­tion of alpha pow­er in pari­etal, but notably also in audi­to­ry cor­ti­cal regions. This alpha pow­er lat­er­al­iza­tion was not main­tained steadi­ly but fluc­tu­at­ed in syn­chrony with the speech rate and lagged the time course of low-fre­quen­cy (1–5 Hz) sen­so­ry syn­chro­niza­tion. High­er ampli­tude of alpha pow­er mod­u­la­tion at the speech rate was pre­dic­tive of a listener’s enhanced per­for­mance of stream-spe­cif­ic speech com­pre­hen­sion. Our find­ings demon­strate that alpha pow­er lat­er­al­iza­tion is mod­u­lat­ed in tune with the sen­so­ry input and acts as a spa­tiotem­po­ral fil­ter con­trol­ling the read-out of sen­so­ry content.
Categories
EEG / MEG Neural Oscillations Posters Publications

Herb­st & Lan­dau on Rhythms for cog­ni­tion: the case of tem­po­ral processing

In an invit­ed review in Cur­rent Opin­ion in Behav­ioral Sci­ences, Sophie Herb­st and Ayelet Lan­dau (The Hebrew Uni­ver­si­ty of Jerusalem) dis­cuss the role of spon­ta­neous and stim­u­lus-evoked neur­al oscil­la­tions in tem­po­ral processing.

Now avail­able online:

http://authors.elsevier.com/a/1SZuN8MqMiN8Ar

Categories
Auditory Working Memory EEG / MEG Executive Functions Neural Oscillations Papers Publications

New Paper by Lim, Wöst­mann, & Obleser in Jour­nal of Neuroscience

Can you atten­tive­ly “high­light” audi­to­ry traces in mem­o­ry? If so, what are poten­tial neur­al mech­a­nisms of it?

Sung-Joo Lim’s paper in J Neurosci;

Selec­tive Atten­tion to Audi­to­ry Mem­o­ry Neu­ral­ly Enhances Per­cep­tu­al Precision

is now avail­able online (full text).

Abstract
Selec­tive atten­tion to a task-rel­e­vant stim­u­lus facil­i­tates encod­ing of that stim­u­lus into a work­ing mem­o­ry rep­re­sen­ta­tion. It is less clear whether selec­tive atten­tion also improves the pre­ci­sion of a stim­u­lus already rep­re­sent­ed in mem­o­ry. Here, we inves­ti­gate the behav­ioral and neur­al dynam­ics of selec­tive atten­tion to rep­re­sen­ta­tions in audi­to­ry work­ing mem­o­ry (i.e., audi­to­ry objects) using psy­chophys­i­cal mod­el­ing and mod­el-based analy­sis of elec­troen­cephalo­graph­ic sig­nals. Human lis­ten­ers per­formed a syl­la­ble pitch dis­crim­i­na­tion task where two syl­la­bles served as to-be-encod­ed audi­to­ry objects. Valid (vs neu­tral) retroac­tive cues were pre­sent­ed dur­ing reten­tion to allow lis­ten­ers to selec­tive­ly attend to the to-be-probed audi­to­ry object in mem­o­ry. Behav­ioral­ly, lis­ten­ers rep­re­sent­ed audi­to­ry objects in mem­o­ry more pre­cise­ly (expressed by steep­er slopes of a psy­cho­me­t­ric curve) and made faster per­cep­tu­al deci­sions when valid com­pared to neu­tral retrocues were pre­sent­ed. Neu­ral­ly, valid com­pared to neu­tral retrocues elicit­ed a larg­er fron­to­cen­tral sus­tained neg­a­tiv­i­ty in the evoked poten­tial as well as enhanced pari­etal alpha/low-beta oscil­la­to­ry pow­er (9–18 Hz) dur­ing mem­o­ry reten­tion. Crit­i­cal­ly, indi­vid­ual mag­ni­tudes of alpha oscil­la­to­ry pow­er (7–11 Hz) mod­u­la­tion pre­dict­ed the degree to which valid retrocues ben­e­fit­ted indi­vid­u­als’ behav­ior. Our results indi­cate that selec­tive atten­tion to a spe­cif­ic object in audi­to­ry mem­o­ry does ben­e­fit human per­for­mance not by sim­ply reduc­ing mem­o­ry load, but by active­ly engag­ing com­ple­men­tary neur­al resources to sharp­en the pre­ci­sion of the task-rel­e­vant object in memory.

Con­grats!

Categories
EEG / MEG Neural Oscillations Papers Publications

New paper by Hen­ry, Her­rmann, & Obleser in Jour­nal of Neuroscience

For­mer Oble­ser­lab post­doc Mol­ly Hen­ry with Björn Her­rmann and Jonas Obleser has a new pub­li­ca­tion in press at Jour­nal of Neuroscience.

Neur­al microstates gov­ern per­cep­tion of audi­to­ry input with­out rhyth­mic structure

by Hen­ry, MJ, Her­mann, B, Obleser, J (in press). J Neurosci.

In devi­a­tion from Molly’s for­mer par­a­digms, we here aimed at bet­ter under­stand­ing the role of oscil­la­to­ry (as well as non-oscil­la­to­ry) slow neur­al activ­i­ty in shap­ing audi­to­ry per­cep­tion when the stim­u­lus is devoid of any rhyth­mic structure.

For a change, the sig­nif­i­cance state­ment and a teas­er fig­ure are shown below.

fluctuation

Abstract
Our abil­i­ty to hear faint sounds fluc­tu­ates togeth­er with slow brain activ­i­ty that syn­chro­nizes with envi­ron­men­tal rhythms. How­ev­er, it is so far not known how brain activ­i­ty at dif­fer­ent time scales might inter­act to influ­ence per­cep­tion when there is no rhythm with which brain activ­i­ty can syn­chro­nize. Here, we used elec­troen­cephalog­ra­phy (EEG) to mea­sure brain activ­i­ty while par­tic­i­pants lis­tened for short silences that inter­rupt­ed ongo­ing noise. We exam­ined brain activ­i­ty in three dif­fer­ent fre­quen­cy bands: delta, theta, and alpha. Par­tic­i­pants’ abil­i­ty to detect gaps depend­ed on dif­fer­ent num­bers of fre­quen­cy bands — some­times one, two, or three — at dif­fer­ent times. Changes in the num­ber of fre­quen­cy bands that pre­dict per­cep­tion are a hall­mark of a com­plex neur­al system.
Categories
Auditory Working Memory Degraded Acoustics EEG / MEG Executive Functions Neural Oscillations Papers Publications

[UPDATE] New review paper by Wilsch & Obleser in press: What works in audi­to­ry work­ing memory?

AC alum­na Anna Wilsch (now Uni­ver­si­ty of Old­en­burg) has a new review paper in press in a spe­cial issue on audi­to­ry work­ing mem­o­ry, curat­ed by Jochen Kaiser (Frank­furt) and Michael Brosch (Magde­burg) in “Brain Research”. We pro­vide a review on neur­al oscil­la­to­ry sig­na­tures of (var­i­ous forms of) audi­to­ry short-term memory.

Wilsch, A., Obleser, J. (in press). What works in audi­to­ry work­ing mem­o­ry? A neur­al oscil­la­tions per­spec­tive. Brain Research

Watch out for that spe­cial issue, as it will have an excel­lent ros­ter of col­leagues con­tribut­ing, and we are proud to be part of it.

The abstract is giv­en below.

Abstract
Work­ing mem­o­ry is a lim­it­ed resource: Brains can only main­tain small amounts of sen­so­ry input (mem­o­ry load) over a brief peri­od of time (mem­o­ry decay). The dynam­ics of slow neur­al oscil­la­tions as record­ed using mag­ne­to- and elec­troen­cephalog­ra­phy (M/EEG) pro­vide a win­dow into the neur­al mechan­ics of these lim­i­ta­tions. Espe­cial­ly oscil­la­tions in the alpha range (8–13 Hz) are a sen­si­tive mark­er for mem­o­ry load. More­over, accord­ing to cur­rent mod­els, the resul­tant work­ing mem­o­ry load is deter­mined by the rel­a­tive noise in the neur­al rep­re­sen­ta­tion of main­tained infor­ma­tion. The audi­to­ry domain allows mem­o­ry researchers to apply and test the con­cept of noise quite lit­er­al­ly: Employ­ing degrad­ed stim­u­lus acoustics increas­es mem­o­ry load and, at the same time, al- lows assess­ing the cog­ni­tive resources required to process speech in noise in an eco­log­i­cal­ly valid and clin­i­cal­ly rel­e­vant way. The present review first sum­ma­rizes recent find­ings on neur­al oscil­la­tions, espe­cial­ly alpha pow­er, and how they reflect mem­o­ry load and mem­o­ry decay in audi­to­ry work­ing mem­o­ry. The focus is specif­i­cal­ly on mem­o­ry load result­ing from acoustic degra­da­tion. These find­ings are then con­trast­ed with con­tex­tu­al fac­tors that ben­e­fit neur­al as well as behav­ioral mark­ers of mem­o­ry per­for­mance, by reduc­ing rep­re­sen­ta­tion­al noise. We end on dis­cussing the func­tion­al role of alpha pow­er in audi­to­ry work­ing mem­o­ry and sug­gest exten­sions of the cur­rent method­olog­i­cal toolkit. 
[Update]

Check out the arti­cle online.