Category: Brain stimulation

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Auditory Cortex Auditory Neuroscience Auditory Perception Brain stimulation Clinical relevance Neural Oscillations Papers Psychiatry Psychology Voice

New Review paper on Cir­ca­di­an Rhythms in Audi­to­ry Hal­lu­ci­na­tions and Psy­chosis to come out in “Acta Physiologica”

As part of our increased efforts to under­stand the impact of chrono­bi­ol­o­gy in sen­sa­tion and per­cep­tion, a new review arti­cle by senior researcher Hong-Viet Ngo in the lab and Jonas Obleser, togeth­er with psy­chi­a­trist Christi­na Andreou and chrononeu­ro­phys­i­ol­o­gist Hen­rik Oster is forthcoming!

The paper sum­maris­es our (sketchy) knowl­edge on how cir­ca­di­an rhythms impact audi­to­ry hal­lu­ci­na­tion propen­si­ty, and how key neur­al sig­na­tures E:I (dys-)balance and dopamin­er­gic sig­nalling joint­ly might con­tribute to hal­lu­ci­na­tions as a key symp­tom in  psy­chosis. The paper has been accept­ed in the clas­sic jour­nal Acta Phys­i­o­log­i­ca. A preprint ver­sion is avail­able here.

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Brain stimulation Memory Papers Psychiatry Publications Sleep

New Paper in Jour­nal of Sleep Research by Wein­hold et al.

In a col­lab­o­ra­tion with Sara Lena Wein­hold and Robert Göder at the Chris­t­ian-Albrechts-Uni­ver­si­ty Kiel, Hong-Viet V. Ngo recent­ly pub­lished a study inves­ti­gat­ing the influ­ence of audi­to­ry stim­u­la­tion dur­ing sleep on mem­o­ry con­sol­i­da­tion in peo­ple with schizophrenia.

The study shows that audi­to­ry stim­u­la­tion tar­get­ing slow oscil­la­tions – a key rhythm medi­at­ing mem­o­ry pro­cess­ing – in real-time in peo­ple with schiz­o­phre­nia results in an elec­tro­phys­i­o­log­i­cal response that is sim­i­lar to that in healthy par­tic­i­pants. Albeit an absent effect of stim­u­la­tion on mem­o­ry con­sol­i­da­tion, the authors found the stronger the slow oscil­la­tion enhance­ment the less par­tic­i­pants for­got, i.e., the bet­ter mem­o­ry per­for­mance was, the fol­low­ing morning.

Thus, this paper not only con­firms the over­all fea­si­bil­i­ty of this approach and pro­vides essen­tial elec­tro­phys­i­o­log­i­cal insights. It fur­ther­more high­lights the poten­tial of audi­to­ry stim­u­la­tion to pro­vide alter­na­tive treat­ments for sleep-relat­ed dys­func­tions in patients with schiz­o­phre­nia. The arti­cle is avail­able here.

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Auditory Neuroscience Brain stimulation EEG / MEG Executive Functions fMRI Grants Job Offers Semantics Speech

We are hir­ing: new PhD train­ing oppor­tu­ni­ty start­ing spring 2022

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Attention Auditory Cortex Brain stimulation Papers Perception Publications

New paper in press in JASA: Kre­it­e­wolf et al. on the role of voice-fea­ture con­ti­nu­ity for cock­tail-par­ty listening

Oble­ser­lab post­doc Jens Kre­it­e­wolf is in press in The Jour­nal of the Acousti­cal Soci­ety of America!

Togeth­er with our col­leagues, Marc Schön­wies­ner (Montreal/Leipzig), Samuel Math­ias (Yale), and Régis Tra­peau (Montreal/Marseille), we inves­ti­gat­ed the roles of two of the most salient voice fea­tures, glot­tal-pulse rate (GPR) and vocal-tract length (VTL), for per­cep­tu­al group­ing in the cock­tail par­ty. Using care­ful­ly con­trolled stim­uli, we show that lis­ten­ers exploit con­ti­nu­ity in both voice fea­tures to solve the cock­tail-par­ty prob­lem, but that VTL con­ti­nu­ity plays a stronger role for per­cep­tu­al group­ing than GPR con­ti­nu­ity. Our find­ings are in line with the dif­fer­en­tial impor­tance of VTL and GPR for the iden­ti­fi­ca­tion of nat­ur­al talk­ers and have clin­i­cal­ly rel­e­vant impli­ca­tions for cock­tail-par­ty lis­ten­ing in cochlear-implant users.

Data were record­ed using the Dome at BRAMS dur­ing Jens’ ACN Eras­mus Mundus exchange in Montreal.

The paper is avail­able as preprint:

https://www.biorxiv.org/content/early/2018/07/30/379545

 

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Auditory Cortex Brain stimulation Papers Psychology Publications

New paper in press at eNeu­ro: Herb­st, Fiedler and Obleser on track­ing tem­po­ral haz­ard in the human EEG

Here, we show that human par­tic­i­pants use implic­it mod­u­la­tions of  tem­po­ral haz­ard, the prob­a­bil­i­ty of an item to occur at a cer­tain moment in time giv­en it has not yet occurred, when per­form­ing a pitch dis­crim­i­na­tion task. Using an encod­ing mod­el approach allows us to iso­late the track­ing of  tem­po­ral haz­ard by the time domain EEG sig­nal, notably by the sup­ple­men­tary motor area, a region known for its impli­ca­tion in timing.

The paper is avail­able as preprint:

https://www.biorxiv.org/content/early/2017/12/14/233551

Herb­st SK, Fiedler L & Obleser J (2018), Track­ing tem­po­ral haz­ard in the human elec­troen­cephalo­gram using a for­ward encod­ing mod­el. eNeu­ro (in press). 

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Attention Auditory Cortex Auditory Perception Brain stimulation Papers Psychology Publications Speech

New paper in press in Brain Stim­u­la­tion: Wöst­mann, Vosskuhl, Obleser, and Her­rmann demon­strate that exter­nal­ly ampli­fied oscil­la­tions affect audi­to­ry spa­tial attention

In a fine col­lab­o­ra­tion we com­bine exper­tise on audi­to­ry cog­ni­tion (Malte Wöst­mann & Jonas Obleser, Uni­ver­si­ty of Lübeck) and brain stim­u­la­tion (Johannes Vosskuhl and Christoph S Her­rmann, Uni­ver­si­ty of Old­en­burg) to show that exter­nal­ly stim­u­lat­ed alpha and gam­ma oscil­la­tions dif­fer­en­tial­ly affect spa­tial atten­tion to speech. Our par­tic­i­pants per­formed a dichot­ic lis­ten­ing task while being stim­u­lat­ed using tran­scra­nial alter­nat­ing cur­rent stim­u­la­tion (tACS) at alpha or gam­ma fre­quen­cy (vs sham) on the left hemi­sphere. Alpha-tACS rel­a­tive­ly decreased recall of tar­gets con­tralat­er­al to stim­u­la­tion, while gam­ma-tACS reversed this effect. These results sug­gest that exter­nal­ly ampli­fied oscil­la­tions are func­tion­al­ly rel­e­vant to spa­tial attention.

Wöst­mann, M., Vosskuhl, J., Obleser, J., & Her­rmann, C.S. (2018). Oppo­site effects of lat­er­alised tran­scra­nial alpha ver­sus gam­ma stim­u­la­tion on audi­to­ry spa­tial attention.

Now avail­able online:

https://www.sciencedirect.com/science/article/pii/S1935861X18301074

Abstract:

Back­ground: Spa­tial atten­tion rel­a­tive­ly increas­es the pow­er of neur­al 10-Hz alpha oscil­la­tions in the hemi­sphere ipsi­lat­er­al to atten­tion, and decreas­es alpha pow­er in the con­tralat­er­al hemi­sphere. For gam­ma oscil­la­tions (>40 Hz), the oppo­site effect has been observed. The func­tion­al roles of lat­er­alised oscil­la­tions for atten­tion are cur­rent­ly unclear.

Hypoth­e­sis: If lat­er­alised oscil­la­tions are func­tion­al­ly rel­e­vant for atten­tion, tran­scra­nial stim­u­la­tion of alpha ver­sus gam­ma oscil­la­tions in one hemi­sphere should dif­fer­en­tial­ly mod­u­late the accu­ra­cy of spa­tial atten­tion to the ipsi-ver­sus con­tralat­er­al side.

Meth­ods: 20 human par­tic­i­pants per­formed a dichot­ic lis­ten­ing task under con­tin­u­ous tran­scra­nial alter­nat­ing cur­rent stim­u­la­tion (tACS, vs sham) at alpha (10 Hz) or gam­ma (47 Hz) fre­quen­cy. On each tri­al, par­tic­i­pants attend­ed to four spo­ken num­bers on the left or right ear, while ignor­ing num­bers on the oth­er ear. In order to stim­u­late a left tem­poro-pari­etal cor­tex region, which is known to show marked mod­u­la­tions of alpha pow­er dur­ing audi­to­ry spa­tial atten­tion, tACS (1 mA peak-to-peak ampli­tude) was applied at elec­trode posi­tions TP7 and FC5 over the left hemisphere.

Results: As pre­dict­ed, uni­hemi­spher­ic alpha-tACS rel­a­tive­ly decreased the recall of tar­gets con­tralat­er­al to stim­u­la­tion, but increased recall of ipsi­lat­er­al tar­gets. Impor­tant­ly, this spa­tial pat­tern of results was reversed for gamma-tACS.

Con­clu­sions: Results pro­vide a proof of con­cept that tran­scra­nial­ly stim­u­lat­ed oscil­la­tions can enhance spa­tial atten­tion and facil­i­tate atten­tion­al selec­tion of speech. Fur­ther­more, oppo­site effects of alpha ver­sus gam­ma stim­u­la­tion sup­port the view that states of high alpha are incom­men­su­rate with active neur­al pro­cess­ing as reflect­ed by states of high gamma.

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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.