New paper in press in ‘Neu­roim­age’: Alavash, Lim, et al

Oble­ser­lab post­doc Mohsen Alavash and Oble­ser­lab Alum­na Sung-Joo Lim are in press at Neu­roim­age!

They argue with data from a place­bo-con­trolled dopamin­er­gic inter­ven­tion study that BOLD sig­nal vari­abil­i­ty and the func­tion­al con­nec­tome are sur­pris­ing­ly clear­ly affect­ed by L-Dopa, and (ii) that the degree of change in these met­rics can explain the degree to which indi­vid­u­als will prof­it from L-DOPA in per­form­ing the chal­leng­ing lis­ten­ing task (while oth­ers dont; Preprint here ).

Alavash, M., Lim, S.J., Thiel, C., Sehm, B., Deser­no, L., & Obleser, J. (2018) Dopamin­er­gic mod­u­la­tion of hemo­dy­nam­ic sig­nal vari­abil­i­ty and the func­tion­al con­nec­tome dur­ing cog­ni­tive per­for­mance. Neu­roim­age. In press.

— Thanks also and in par­tic­u­lar to our col­leagues Chris­tiane Thiel of Old­en­burg, and Bern­hard Sehm and Lorenz Deser­no of Leipzig, who helped us made this large-scale L-DOPA project hap­pen!

 

 

19. January 2018 by Jonas
Categories: Adaptive Control, Attention, Auditory Working Memory, Clinical relevance, Executive Functions, fMRI, Papers, Psychology, Publications, Uncategorized |

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.

17. January 2018 by Jonas
Categories: Auditory Cortex, Auditory Neuroscience, Brain stimulation, Clinical relevance, Degraded Acoustics, Hearing Loss, Neural Oscillations, Neural Phase, Papers, Psychology, Speech |

SNAP 2017 was a vast suc­cess

SNAP 2017 took place on Decem­ber 8 and 9 in Lübeck, Ger­many.

Nine inter­na­tion­al­ly esteemed speak­ers and in total more than six­ty researchers from all over Europe, Cana­da and the US made the sec­ond Sig­nal and Noise Along the Audi­to­ry Path­way work­shop a mem­o­rable occa­sion in audi­to­ry neu­ro­science.

Thanks to every­body for com­ing out!, and see you all again for SNAP 2019, at a loca­tion to be announced.

18. December 2017 by Simon Grosnick
Categories: Auditory Neuroscience, Auditory Speech Processing, Psychology | Tags: , , , |

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.

 

 

16. December 2017 by Simon Grosnick
Categories: Ageing, Auditory Neuroscience, EEG / MEG, Papers, Publications | Tags: , , , |

Want to come work with us?

Post­doc posi­tion in the Obleser lab, in the ERC-fund­ed project “Audadapt” — dead­line for appli­ca­tions very soon! (Nov 30 2017). Check out all appli­ca­tions details here!

26. November 2017 by Jonas
Categories: Adaptive Control, Ageing, Job Offers, Speech, Uncategorized |

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