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Category: EEG / MEG

Categories
Auditory Cortex EEG / MEG Papers Perception Publications

New paper in press in the Euro­pean Jour­nal of Neu­ro­science: Wöst­mann et al demon­strate that the pow­er of pres­tim­u­lus alpha oscil­la­tions direct­ly relates to con­fi­dence in pitch-discrimination

What is the mech­a­nis­tic rel­e­vance of neur­al alpha oscil­la­tions (~10 Hz) for per­cep­tion? To answer this ques­tion, we analysed EEG data from a task that required par­tic­i­pants to com­pare the pitch of two tones that were, unbe­knownst to par­tic­i­pants, iden­ti­cal. Impor­tant­ly, this task entire­ly removed poten­tial con­founds of vary­ing evi­dence in the stim­u­lus or vary­ing accu­ra­cy. We found that high­er pres­tim­u­lus alpha pow­er cor­re­lat­ed with low­er con­fi­dence in pitch dis­crim­i­na­tion. These results demon­strate that the rela­tion­ship of pres­tim­u­lus alpha pow­er and deci­sion con­fi­dence is direct in nature and, that it shows up in the audi­to­ry modal­i­ty sim­i­lar to what has been shown before in vision and somatosen­sa­tion. Our find­ings sup­port the view that low­er pres­tim­u­lus alpha pow­er enhances neur­al base­line excitability.

The paper is avail­able as preprint here.

Categories
Adaptive Control Auditory Cortex Auditory Neuroscience Auditory Working Memory Neural Oscillations Papers Perception Psychology Uncategorized

New paper in The Jour­nal of Neu­ro­science: Wilsch et al.., Tem­po­ral expec­ta­tion mod­u­lates the cor­ti­cal dynam­ics of short-term memory

Con­grat­u­la­tions to Oble­ser­lab alum­na Anna Wilsch, who is – for now – leav­ing acad­e­mia on a true high with her lat­est offer­ing on how tem­po­ral expec­ta­tions (“fore­knowl­edge” about when some­thing is to hap­pen) shape the neur­al make-up of memory!

Record­ed while the Oble­ser­lab was still in Leipzig at the Max Planck, and analysed with great input from our co-authors Mol­ly Hen­ry, Björn Her­rmann as well as Christoph Her­rmann (Old­en­burg), Anna used Mag­ne­toen­cephalog­ra­phy in an intri­cate but ulti­mate­ly very sim­ple sen­so­ry-mem­o­ry paradigm.

 

While sen­so­ry mem­o­ries of the phys­i­cal world fade quick­ly, Anna here shows that this decay of short-term mem­o­ry can be coun­ter­act­ed by tem­po­ral expectation.

Notably, spa­tial­ly dis­trib­uted cor­ti­cal pat­terns of alpha (8−−13 Hz) pow­er showed oppos­ing effects in audi­to­ry vs. visu­al sen­so­ry cor­tices. More­over, alpha-tuned con­nec­tiv­i­ty changes with­in supramodal atten­tion net­works reflect the allo­ca­tion of neur­al resources as short-term mem­o­ry rep­re­sen­ta­tions fade.

— to be updat­ed as the paper will become avail­able online –

Categories
Auditory Cortex Auditory Neuroscience Brain stimulation Clinical relevance Degraded Acoustics Hearing Loss Neural Oscillations Neural Phase Papers Psychology Speech

New paper in press with the Old­en­burg brain-stim­u­la­tion crew!

AC alum­na Anna Wilsch has a new paper in press in Neu­roim­age, with Toralf Neul­ing, Jonas Obleser, and Christoph Her­rmann: “Tran­scra­nial alter­nat­ing cur­rent stim­u­la­tion with speech envelopes mod­u­lates speech com­pre­hen­sion”. In this proof-of-concept–like paper, we demon­strate that using the speech enve­lope as a “pilot sig­nal” for elec­tri­cal­ly stim­u­lat­ing the human brain, while a lis­ten­er tries to com­pre­hend that speech sig­nal buried in noise, does mod­u­late the listener’s speech–in–noise com­pre­hen­sion abilities.

The Preprint is here, … 

… while the abstract goes like this:
Cor­ti­cal entrain­ment of the audi­to­ry cor­tex to the broad­band tem­po­ral enve­lope of a speech sig­nal is cru­cial for speech com­pre­hen­sion. Entrain­ment results in phas­es of high and low neur­al excitabil­i­ty, which struc­ture and decode the incom­ing speech sig­nal. Entrain­ment to speech is strongest in the theta fre­quen­cy range (4−8 Hz), the aver­age fre­quen­cy of the speech enve­lope. If a speech sig­nal is degrad­ed, entrain­ment to the speech enve­lope is weak­er and speech intel­li­gi­bil­i­ty declines. Besides per­cep­tu­al­ly evoked cor­ti­cal entrain­ment, tran­scra­nial alter­nat­ing cur­rent stim­u­la­tion (tACS) entrains neur­al oscil­la­tions by apply­ing an elec­tric sig­nal to the brain. Accord­ing­ly, tACS-induced entrain­ment in audi­to­ry cor­tex has been shown to improve audi­to­ry per­cep­tion. The aim of the cur­rent study was to mod­u­late speech intel­li­gi­bil­i­ty exter­nal­ly by means of tACS such that the elec­tric cur­rent cor­re­sponds to the enve­lope of the pre­sent­ed speech stream (i.e., enve­lope-tACS). Par­tic­i­pants per­formed the Old­en­burg sen­tence test with sen­tences pre­sent­ed in noise in com­bi­na­tion with enve­lope-tACS. Crit­i­cal­ly, tACS was induced at time lags of 0 to 250 ms in 50-ms steps rel­a­tive to sen­tence onset (audi­to­ry stim­uli were simul­ta­ne­ous to or pre­ced­ed tACS). We per­formed sin­gle- sub­ject sinu­soidal, lin­ear, and qua­drat­ic fits to the sen­tence com­pre­hen­sion per­for­mance across the time lags. We could show that the sinu­soidal fit described the mod­u­la­tion of sen­tence com­pre­hen­sion best. Impor­tant­ly, the aver­age fre­quen­cy of the sinu­soidal fit was 5.12 Hz, cor­re­spond­ing to the peaks of the ampli­tude spec­trum of the stim­u­lat­ed envelopes. This find­ing was sup­port­ed by a sig­nif­i­cant 5‑Hz peak in the aver­age pow­er spec­trum of indi­vid­ual per­for­mance time series. Alto­geth­er, enve­lope tACS mod­u­lates intel­li­gi­bil­i­ty of speech in noise, pre­sum­ably by enhanc­ing and dis­rupt­ing (time lag with in- or out-of-phase stim­u­la­tion, respec­tive­ly) cor­ti­cal entrain­ment to the speech enve­lope in audi­to­ry cortex.
Categories
Ageing Auditory Neuroscience EEG / MEG Papers Publications

New paper online by Waschke, Wöst­mann & Obleser

Read all about neur­al irreg­u­lar­i­ty in aging brains and how it relates to per­cep­tu­al deci­sions: New paper by PhD stu­dent Leo Waschke. 

Now avail­able online:
https://goo.gl/F4dFfe

Abstract

Sen­so­ry rep­re­sen­ta­tions, and thus human per­cepts, of the phys­i­cal world are sus­cep­ti­ble to fluc­tu­a­tions in brain state or “neur­al irreg­u­lar­i­ty”. Fur­ther­more, aging brains dis­play altered lev­els of neur­al irreg­u­lar­i­ty. We here show that a sin­gle, with­in-tri­al, infor­ma­tion-the­o­ret­ic mea­sure (weight­ed per­mu­ta­tion entropy) cap­tures neur­al irreg­u­lar­i­ty in the human elec­troen­cephalo­gram as a proxy for both, trait-like dif­fer­ences between indi­vid­u­als of vary­ing age, and state-like fluc­tu­a­tions that bias per­cep­tu­al deci­sions. First, the over­all lev­el of neur­al irreg­u­lar­i­ty increased with par­tic­i­pants’ age, par­al­leled by a decrease in vari­abil­i­ty over time, like­ly index­ing age-relat­ed changes at struc­tur­al and func­tion­al lev­els of brain activ­i­ty. Sec­ond, states of high­er neur­al irreg­u­lar­i­ty were asso­ci­at­ed with opti­mized sen­so­ry encod­ing and a sub­se­quent­ly increased prob­a­bil­i­ty of choos­ing the first of two phys­i­cal­ly iden­ti­cal stim­uli to be high­er in pitch. In sum, neur­al irreg­u­lar­i­ty not only char­ac­ter­izes behav­ioural­ly rel­e­vant brain states, but also can iden­ti­fy trait-like changes that come with age. 

 

 

Categories
Ageing Attention Auditory Cortex Auditory Neuroscience Editorial Notes EEG / MEG Executive Functions Neural Phase Posters

Come see us @ Neu­ro­science 2017 in DC

Will be at the Soci­ety for Neu­ro­science Meet­ing next week in DC? Come find us in the Wednes­day after­noon ses­sion with a bunch of (we think) very cool atten­tion-relat­ed posters (Poster boards UU42–UU46):

804.06. Audi­to­ry atten­tion and pre­dic­tive pro­cess­ing co-mod­u­late speech com­pre­hen­sion in mid­dle-aged adults
*S. TUNE, M. WÖSTMANN, J. OBLESER;

804.05. Implic­it tem­po­ral pre­dictabil­i­ty enhances audi­to­ry pitch-dis­crim­i­na­tion sensitivity
*S. K. HERBST, M. PLÖCHL, A. HERRMANN, J. OBLESER;

804.09. Are visu­al and audi­to­ry detec­tion per­for­mance dri­ven by a supramodal atten­tion­al rhythm?
*M. PLOECHL, S. KASTNER, I. C. FIEBELKORN, J. OBLESER;

804.08. Spa­tio-tem­po­ral expec­ta­tions exert dif­fer­en­tial effects on visu­al and audi­to­ry discrimination
*A. WILSCH, J. OBLESER, C. E. SCHROEDER, C. S. HERRMANN, S. HAEGENS

804.07. Tran­scra­nial 10-Hz stim­u­la­tion but also eye clo­sure mod­u­late audi­to­ry attention
*M. WÖSTMANN, L.-M. SCHMITT, J. VOSSKUHL, C. S. HERRMANN, J. OBLESER

Categories
Attention Auditory Neuroscience EEG / MEG Evoked Activity Neural Oscillations Neural Phase Papers Perception Psychology Uncategorized

New paper in Plos Biol­o­gy: Com­ment by Obleser, Hen­ry, & Lakatos

My col­leagues and col­lab­o­ra­tor Peter Lakatos and Mol­ly Hen­ry and I took to our desks and Mat­lab con­soles, when Assaf Bres­ka and Leon Deouell came out ear­li­er this year with their paper in Plos Biology.

We had a few things to say about what we then per­ceived as a rather pes­simistic assess­ment of neur­al entrain­ment. How­ev­er, since then a great and quite fru­ti­ful dis­cus­sion has emerged, now pub­lished in Plos Biology:

Obleser J, Hen­ry, MJ, & Lakatos, P. What do we talk about when we talk about rhythm?, Plos Biol­o­gy 2017

Mean­while, Bres­ka and Deouell added some more behav­iour­al data and replied to us (now also pub­lished).

— Enjoy!

 

Categories
Adaptive Control Ageing Auditory Cortex Auditory Neuroscience EEG / MEG Evoked Activity Executive Functions Neural Oscillations Neural Phase Papers Perception Publications

New paper in press: Hen­ry et al., Nature Communications

Here comes a new paper in Nature Com­mu­ni­ca­tions by for­mer AC post­doc Mol­ly Hen­ry, with for­mer fel­low post­doc AC alum­nus Björn Her­rmann, our tire­less lab man­ag­er, Dun­ja Kunke, and myself! It is a late (to us quite impor­tant) result from our lab’s tenure at the Max Planck in Leipzig, 

Hen­ry, M.J., Her­rmann, B., Kunke, D., Obleser, J. (In press). Aging affects the bal­ance of neur­al entrain­ment and top-down neur­al mod­u­la­tion in the lis­ten­ing brain. Nature Communications. 

—Con­grat­u­la­tions, Molly!

Categories
Attention Auditory Cortex Auditory Neuroscience Auditory Speech Processing EEG / MEG Papers Psychology Publications

New paper in press in Jour­nal of Neur­al Engi­neer­ing: Fiedler et al. on in-ear-EEG and the focus of audi­to­ry attention

Towards a brain-con­trolled hear­ing aid: PhD stu­dent Lorenz Fiedler shows how attend­ed and ignored audi­to­ry streams are dif­fer­ent­ly rep­re­sent­ed in the neur­al respons­es and how the focus of audi­to­ry atten­tion can be extract­ed from EEG sig­nals record­ed at elec­trodes placed inside the ear-canal and around the ear.

Abstract
Objec­tive. Con­ven­tion­al, mul­ti-chan­nel scalp elec­troen­cephalog­ra­phy (EEG) allows the iden­ti­fi­ca­tion of the attend­ed speak­er in con­cur­rent-lis­ten­ing (‘cock­tail par­ty’) sce­nar­ios. This implies that EEG might pro­vide valu­able infor­ma­tion to com­ple­ment hear­ing aids with some form of EEG and to install a lev­el of neu­ro-feed­back. Approach. To inves­ti­gate whether a listener’s atten­tion­al focus can be detect­ed from sin­gle-chan­nel hear­ing-aid-com­pat­i­ble EEG con­fig­u­ra­tions, we record­ed EEG from three elec­trodes inside the ear canal (‘in-Ear-EEG’) and addi­tion­al­ly from 64 elec­trodes on the scalp. In two dif­fer­ent, con­cur­rent lis­ten­ing tasks, par­tic­i­pants ( n  =  7) were fit­ted with indi­vid­u­al­ized in-Ear-EEG pieces and were either asked to attend to one of two dichot­i­cal­ly-pre­sent­ed, con­cur­rent tone streams or to one of two diot­i­cal­ly-pre­sent­ed, con­cur­rent audio­books. A for­ward encod­ing mod­el was trained to pre­dict the EEG response at sin­gle EEG chan­nels. Main results. Each indi­vid­ual par­tic­i­pants’ atten­tion­al focus could be detect­ed from sin­gle-chan­nel EEG response record­ed from short-dis­tance con­fig­u­ra­tions con­sist­ing only of a sin­gle in-Ear-EEG elec­trode and an adja­cent scalp-EEG elec­trode. The dif­fer­ences in neur­al respons­es to attend­ed and ignored stim­uli were con­sis­tent in mor­phol­o­gy (i.e. polar­i­ty and laten­cy of com­po­nents) across sub­jects. Sig­nif­i­cance. In sum, our find­ings show that the EEG response from a sin­gle-chan­nel, hear­ing-aid-com­pat­i­ble con­fig­u­ra­tion pro­vides valu­able infor­ma­tion to iden­ti­fy a listener’s focus of attention.