Categories
Auditory Neuroscience Auditory Speech Processing EEG / MEG Neural Oscillations Neural Phase Papers Publications Speech

New Paper in PNAS: Hen­ry & Obleser [Updat­ed]

Our new paper on neur­al entrain­ment with spec­tral fluc­tu­a­tions, and its effects on near-thresh­old audi­to­ry per­cep­tion is now online in the “ear­ly edi­tion” of PNAS:

Hen­ry, MJ & Obleser, J (in press):

Fre­quen­cy mod­u­la­tion entrains slow neur­al oscil­la­tions and opti­mizes human lis­ten­ing behavior

Pro­ceed­ings of the Nation­al Acad­e­my of Sci­ences of the Unit­ed States of Amer­i­ca (PNAS)


Here is the abstract:

The human abil­i­ty to con­tin­u­ous­ly track dynam­ic envi­ron­men­tal stim­uli, in par­tic­u­lar speech, is pro­posed to prof­it from “entrain­ment” of endoge­nous neur­al oscil­la­tions, which involves phase reor­ga­ni­za­tion such that “opti­mal” phase comes into line with tem­po­ral­ly expect­ed crit­i­cal events, result­ing in improved pro­cess­ing. The cur­rent exper­i­ment goes beyond pre­vi­ous work in this domain by address­ing two thus far unan­swered ques­tions. First, how gen­er­al is neur­al entrain­ment to envi­ron­men­tal rhythms: Can neur­al oscil­la­tions be entrained by tem­po­ral dynam­ics of ongo­ing rhyth­mic stim­uli with­out abrupt onsets? Sec­ond, does neur­al entrain­ment opti­mize per­for­mance of the per­cep­tu­al sys­tem: Does human audi­to­ry per­cep­tion ben­e­fit from neur­al phase reor­ga­ni­za­tion? In a human elec­troen­cephalog­ra­phy study, lis­ten­ers detect­ed short gaps dis­trib­uted uni­form­ly with respect to the phase angle of a 3‑Hz fre­quen­cy-mod­u­lat­ed stim­u­lus. Lis­ten­ers’ abil­i­ty to detect gaps in the fre­quen­cy-mod­u­lat­ed sound was not uni­form­ly dis­trib­uted in time, but clus­tered in cer­tain pre­ferred phas­es of the mod­u­la­tion. More­over, the opti­mal stim­u­lus phase was indi­vid­u­al­ly deter­mined by the neur­al delta oscil­la­tion entrained by the stim­u­lus. Final­ly, delta phase pre­dict­ed behav­ior bet­ter than stim­u­lus phase or the event-relat­ed poten­tial after the gap. This study demon­strates behav­ioral ben­e­fits of phase realign­ment in response to fre­quen­cy-mod­u­lat­ed audi­to­ry stim­uli, over­all sug­gest­ing that fre­quen­cy fluc­tu­a­tions in nat­ur­al envi­ron­men­tal input pro­vide a pac­ing sig­nal for endoge­nous neur­al oscil­la­tions, there­by influ­enc­ing per­cep­tu­al processing.

NB: There is also a press release by the Max Planck Soci­ety on the topic.

Ref­er­ences

  • Hen­ry MJ, Obleser J. Fre­quen­cy mod­u­la­tion entrains slow neur­al oscil­la­tions and opti­mizes human lis­ten­ing behav­ior. Proc Natl Acad Sci U S A. 2012 Dec 4;109(49):20095–100. PMID: 23151506. [Open with Read]
Categories
Auditory Cortex Auditory Speech Processing fMRI Papers Publications Speech

New paper out: McGet­ti­gan et al., Neuropsychologia


Last years’s lab guest and long-time col­lab­o­ra­tor Car­olyn McGet­ti­gan has put out anoth­er one:

Speech com­pre­hen­sion aid­ed by mul­ti­ple modal­i­ties: Behav­iour­al and neur­al interactions

I had the plea­sure to be involved ini­tial­ly, when Car­olyn con­ceived a lot of this, and when things came togeth­er in the end. Car­olyn nice­ly demon­strates how vary­ing audio and visu­al clar­i­ty comes togeth­er with the seman­tic ben­e­fits a lis­ten­er can get from the famous Kalikow SPIN (speech in noise) sen­tences. The data high­light pos­te­ri­or STS and the fusiform gyrus as sites for con­ver­gence of audi­to­ry, visu­al and lin­guis­tic information.

Check it out!

Ref­er­ences

  • McGet­ti­gan C, Faulkn­er A, Altarel­li I, Obleser J, Baver­stock H, Scott SK. Speech com­pre­hen­sion aid­ed by mul­ti­ple modal­i­ties: behav­iour­al and neur­al inter­ac­tions. Neu­ropsy­cholo­gia. 2012 Apr;50(5):762–76. PMID: 22266262. [Open with Read]
Categories
Auditory Speech Processing Media Publications

3‑D ani­ma­tion of brain acti­va­tions illus­trates the idea of “upstream delegation”

Recent­ly, with a data set dat­ing back to my time in Angela Friederici’s depart­ment, we pro­posed the idea that audi­to­ry sig­nal degra­da­tion would affect the exact con­fig­u­ra­tion of activ­i­ty along the main pro­cess­ing streams of lan­guage, in the supe­ri­or tem­po­ral and infe­ri­or frontal cor­tex. We ten­ta­tive­ly coined this process “upstream del­e­ga­tion”: The acti­va­tions that were dri­ven by increas­ing syn­tac­tic demands, with the chal­lenge of decreas­ing sig­nal qual­i­ty com­ing on top, were all of a sud­den found more “upstream” from where we had locat­ed them with improv­ingsig­nal quality.

In a fas­ci­nat­ing and instruc­tive inter­ac­tive 3‑D ver­sion (Oh, this sound so 1990s but it’s true!) , you can now study and manip­u­late (in the lit­er­al, not the sci­en­tif­ic mis­con­duct-sense) this and var­i­ous oth­er find­ings from Angela’s lab your­self: Fire up Chrome or Fire­fox and Check it out here.
All of this is tak­en from a recent review by Angela [Friederi­ci, AD (2011) Phys­i­o­log­i­cal Reviews, 91(4), 1357–1392], where she lays out her cur­rent take on infe­ri­or frontal cor­tex, the tracts con­nect­ing to and from it, and its role in syn­tax pro­cess­ing. The funky 3‑D stuff is by Ralph Schu­rade. Don’t ask how long it took us to get all the coor­di­nates in place.
Categories
Auditory Perception EEG / MEG Events Evoked Activity Posters Publications Speech

Poster Pre­sen­ta­tions at SFN

There will be two poster pre­sen­ta­tions at SFN in Wash­ing­ton, DC., on the top­ic of audi­to­ry pre­dic­tions in speech per­cep­tion. The first poster, authored by Alexan­dra Ben­dix­en, Math­ias Scharinger, and Jonas Obleser, sum­ma­rizes as follows:

Speech sig­nals are often com­pro­mised by dis­rup­tions orig­i­nat­ing from exter­nal (e.g., mask­ing noise) or inter­nal (e.g., slug­gish artic­u­la­tion) sources. Speech com­pre­hen­sion thus entails detect­ing and replac­ing miss­ing infor­ma­tion based on pre­dic­tive and restora­tive mech­a­nisms. The nature of the under­ly­ing neur­al mech­a­nisms is not yet well under­stood. In the present study, we inves­ti­gat­ed the detec­tion of miss­ing infor­ma­tion by occa­sion­al­ly omit­ting the final con­so­nants of the Ger­man words “Lachs” (salmon) or “Latz” (bib), result­ing in the syl­la­ble “La” (no seman­tic mean­ing). In three dif­fer­ent con­di­tions, stim­u­lus pre­sen­ta­tion was set up so that sub­jects expect­ed only the word “Lachs” (con­di­tion 1), only the word “Latz” (con­di­tion 2), or the words “Lachs” or “Latz” with equal prob­a­bil­i­ty (con­di­tion 3). Thus essen­tial­ly, the final seg­ment was pre­dictable in con­di­tions 1 and 2, but unpre­dictable in con­di­tion 3. Stim­uli were pre­sent­ed out­side the focus of atten­tion while sub­jects were watch­ing a silent video. Brain respons­es were mea­sured with mul­ti-chan­nel elec­troen­cephalo­gram (EEG) record­ings. In all con­di­tions, an omis­sion response was elicit­ed from 125 to 165 ms after the expect­ed onset of the final seg­ment. The omis­sion response shared char­ac­ter­is­tics of the omis­sion mis­match neg­a­tiv­i­ty (MMN) with gen­er­a­tors in audi­to­ry cor­ti­cal areas. Crit­i­cal­ly, the omis­sion response was enhanced in ampli­tude in the two pre­dictable con­di­tions (1, 2) com­pared to the unpre­dictable con­di­tion (3). Vio­lat­ing a strong pre­dic­tion thus elicit­ed a more pro­nounced omis­sion response. Con­sis­tent with a pre­dic­tive cod­ing account, the pro­cess­ing of miss­ing lin­guis­tic infor­ma­tion appears to be mod­u­lat­ed by pre­dic­tive context.

The sec­ond poster looks at sim­i­lar mate­r­i­al, but con­trasts coro­nal [t] with dor­sal [k], yield­ing inter­est­ing asym­me­tries in MMN responses:

Research in audi­to­ry neu­ro­science has lead to a bet­ter under­stand­ing of the neur­al bases of speech per­cep­tion, but the rep­re­sen­ta­tion­al nature of speech sounds with­in words is still a mat­ter of debate. Elec­tro­phys­i­o­log­i­cal research on sin­gle speech sounds pro­vid­ed evi­dence for abstract rep­re­sen­ta­tion­al units that com­prise infor­ma­tion about both acoustic struc­ture and artic­u­la­tor con­fig­u­ra­tion (Phillips et al., 2000), there­by refer­ring to phono­log­i­cal cat­e­gories. Here, we test the pro­cess­ing of word-final con­so­nants dif­fer­ing in their place of artic­u­la­tion (coro­nal [ts] vs. dor­sal [ks]) and acoustic struc­ture, as seen in the time-vary­ing for­mant (res­o­nance) fre­quen­cies. The respec­tive con­so­nants dis­tin­guish between the Ger­man nouns Latz (bib) and Lachs (salmon), record­ed from a female native speak­er. Ini­tial con­so­nant-vow­el sequences were aver­aged across the two nouns in order to avoid coar­tic­u­la­to­ry cues before the release of the con­so­nants. Latz and Lachs served as stan­dard and deviant in a pas­sive odd­ball par­a­digm, while the EEG from 20 par­tic­i­pants was record­ed. The change from stan­dard [ts] to deviant [ks] and vice ver­sa was accom­pa­nied by a dis­cernible Mis­match Neg­a­tiv­i­ty (MMN) response (Näätä­nen et al., 2007). This response showed an intrigu­ing asym­me­try, as seen in a main effect con­di­tion (deviant Latz vs. deviant Lachs, F(1,1920) = 291.84, p < 0.001) of an omnibus mixed-effect mod­el. Cru­cial­ly, the MMN for the deviant Latz was on aver­age more neg­a­tive than the MMN for the deviant Lachs from 135 to 185 ms post deviance onset (p < 0.001). We inter­pret these find­ings as reflect­ing a dif­fer­ence in phono­log­i­cal speci­fici­ty: Fol­low­ing Eulitz and Lahiri, 2004, we assume coro­nal seg­ments ([ts]) to have less spe­cif­ic (‘fea­t­u­ral­ly under­spec­i­fied’) rep­re­sen­ta­tions than dor­sal seg­ments ([ks]). While in stan­dard posi­tion, Lachs acti­vat­ed a mem­o­ry trace with a more spe­cif­ic final con­so­nant for which the deviant pro­vid­ed a stronger mis­match than vice ver­sa, i.e. when Latz acti­vat­ed a mem­o­ry trace with a less spe­cif­ic final con­so­nant. Our results sup­port a mod­el of speech per­cep­tion where sen­so­ry infor­ma­tion is processed in terms of dis­crete units inde­pen­dent of high­er lex­i­cal prop­er­ties, as the asym­me­try can­not be explained by dif­fer­ences in lex­i­cal sur­face fre­quen­cies between Latz and Lachs (both log-fre­quen­cies of 0.69). We can also rule out a fre­quen­cy effect on the seg­men­tal lev­el. Thus, it appears that speech per­cep­tion involves a lev­el of pro­cess­ing where indi­vid­ual seg­men­tal rep­re­sen­ta­tions with­in words are evaluated.

Categories
Auditory Perception Auditory Speech Processing EEG / MEG Evoked Activity Linguistics Papers Place of Articulation Features Publications Speech

New paper out in Jour­nal of Speech, Lan­guage, & Hear­ing Research [Update]

We are hap­py to announce that our paper “Asym­me­tries in the pro­cess­ing of vow­el height” will be appear­ing in the Jour­nal of Speech, Lan­guage, & Hear­ing Research, authored by Philip Mon­a­han, William Idsar­di and Math­ias Scharinger. A short sum­ma­ry is giv­en below:

Pur­pose: Speech per­cep­tion can be described as the trans­for­ma­tion of con­tin­u­ous acoustic infor­ma­tion into dis­crete mem­o­ry rep­re­sen­ta­tions. There­fore, research on neur­al rep­re­sen­ta­tions of speech sounds is par­tic­u­lar­ly impor­tant for a bet­ter under­stand­ing of this trans­for­ma­tion. Speech per­cep­tion mod­els make spe­cif­ic assump­tions regard­ing the rep­re­sen­ta­tion of mid vow­els (e.g., [{varepsilon}]) that are artic­u­lat­ed with a neu­tral posi­tion in regard to height. One hypoth­e­sis is that their rep­re­sen­ta­tion is less spe­cif­ic than the rep­re­sen­ta­tion of vow­els with a more spe­cif­ic posi­tion (e.g., [æ]).

Method: In a mag­ne­toen­cephalog­ra­phy study, we test­ed the under­spec­i­fi­ca­tion of mid vow­el in Amer­i­can Eng­lish. Using a mis­match neg­a­tiv­i­ty (MMN) par­a­digm, mid and low lax vow­els ([{varepsilon}]/[æ]), and high and low lax vow­els ([I]/[æ]), were opposed, and M100/N1 dipole source para­me­ters as well as MMN laten­cy and ampli­tude were examined.

Results: Larg­er MMNs occurred when the mid vow­el [{varepsilon}] was a deviant to the stan­dard [æ], a result con­sis­tent with less spe­cif­ic rep­re­sen­ta­tions for mid vow­els. MMNs of equal mag­ni­tude were elicit­ed in the high–low com­par­i­son, con­sis­tent with more spe­cif­ic rep­re­sen­ta­tions for both high and low vow­els. M100 dipole loca­tions sup­port ear­ly vow­el cat­e­go­riza­tion on the basis of lin­guis­ti­cal­ly rel­e­vant acoustic–phonetic features.

Con­clu­sion: We take our results to reflect an abstract long-term rep­re­sen­ta­tion of vow­els that do not include redun­dant spec­i­fi­ca­tions at very ear­ly stages of pro­cess­ing the speech sig­nal. More­over, the dipole loca­tions indi­cate extrac­tion of dis­tinc­tive fea­tures and their map­ping onto rep­re­sen­ta­tion­al­ly faith­ful cor­ti­cal loca­tions (i.e., a fea­ture map).

[Update]

The paper is avail­able here.

Ref­er­ences

  • Scharinger M, Mon­a­han PJ, Idsar­di WJ. Asym­me­tries in the pro­cess­ing of vow­el height. J Speech Lang Hear Res. 2012 Jun;55(3):903–18. PMID: 22232394. [Open with Read]
Categories
Auditory Speech Processing Degraded Acoustics EEG / MEG Neural Oscillations Noise-Vocoded Speech Papers Publications Speech

New paper accept­ed in Cere­bral Cor­tex [Update]

Obleser, J., Weisz, N. (in press) Sup­pressed alpha oscil­la­tions pre­dict intel­li­gi­bil­i­ty of speech and its acoustic details. Cere­bral Cortex.

[Update]

Paper is avail­able here.

Ref­er­ences

  • Obleser J, Weisz N. Sup­pressed alpha oscil­la­tions pre­dict intel­li­gi­bil­i­ty of speech and its acoustic details. Cereb Cor­tex. 2012 Nov;22(11):2466–77. PMID: 22100354. [Open with Read]
Categories
Auditory Cortex Auditory Neuroscience Auditory Working Memory Clinical relevance EEG / MEG Neural Oscillations Papers Publications Speech

New paper out: Alpha oscil­la­tions in audition

I am also delight­ed to report the fruits of a very recent col­lab­o­ra­tion with Nathan Weisz and his OBOB lab at the Uni­ver­si­ty of Kon­stanz, Germany.

Alpha Rhythms in Audi­tion: Cog­ni­tive and Clin­i­cal Perspectives

In this review paper, which appears in the new, excit­ing “Fron­tiers in Psy­chol­o­gy” jour­nal, we sum the recent evi­dence that alpha oscil­la­tions (here broad­ly defined from 6 to 13 Hz) are play­ing a very inter­est­ing role in the audi­to­ry sys­tem, just as they do in the visu­al and the somatosen­so­ry system.

In essence, we back Ole Jensen’s and oth­ers’ quite pari­mo­nious idea of alpha as a func­tion­al inhi­bi­tion / gat­ing sys­tem across cor­ti­cal areas.

From our own lab, pre­lim­i­nary data from two recent exper­i­ments is includ­ed: On the role of alpha osil­la­tions as a poten­tial mark­er for speech intel­li­gi­bil­i­ty and its acoustic deter­mi­nants, as well as on speech degra­da­tion and work­ing mem­o­ry load and their com­bined reflec­tion in alpha pow­er increases.

 

NB — the final pdf is still lack­ing, and Front Psy­chol is still not list­ed in PubMed. This should not stop you from sub­mit­ting to their excit­ing new jour­nals, as the review process is very fair and effi­cient and the out­reach via free avail­abil­i­ty promis­es to be considerable.

Ref­er­ences

  • Weisz N, Hart­mann T, Müller N, Lorenz I, Obleser J. Alpha rhythms in audi­tion: cog­ni­tive and clin­i­cal per­spec­tives. Front Psy­chol. 2011 Apr 26;2:73. PMID: 21687444. [Open with Read]
Categories
Auditory Neuroscience Auditory Perception fMRI Linguistics Papers Publications Speech

New paper out: “Upstream del­e­ga­tion” for pro­cess­ing of com­plex syn­tax under degrad­ed acoustics

A new paper is about to appear in Neu­roim­age on the inter­ac­tion of syn­tac­tic com­plex­i­ty and acoustic degradation.

It is writ­ten by myself, PhD stu­dent Lars Mey­er, and Angela Friederi­ci. In a way, the paper brings togeth­er one of Angela’s main research ques­tions (which brain cir­cuits medi­ate the pro­cess­ing of syn­tax?) with a long-stand­ing inter­est of mine, that is, how do adverse lis­ten­ing sit­u­a­tions affect the com­pre­hen­sion of speech.

The paper is entitled

Dynam­ic assign­ment of neur­al resources in audi­to­ry com­pre­hen­sion of com­plex sentences

The paper first estab­lish­es that acoustic vari­ants of increas­ing­ly com­plex sen­tences essen­tial­ly behave like writ­ten ver­sions of these sentences.
The data then neat­ly show that pro­cess­ing chal­leng­ing (but legal) syn­tax under var­i­ous lev­els of degra­da­tion has a very dif­fer­ent effect on the neur­al cir­cuits involved than prof­it­ing from seman­tics: While the lat­ter has been shown pre­vi­ous­ly to involve more wide­spread, het­ero­modal brain areas, the dou­ble demand of increas­ing­ly com­plex syn­tax and an increas­ing­ly degrad­ed speech sig­nal (from which the com­plex syn­tax has to be parsed) elic­it an “upstream” shift of acti­va­tion back to less abstract pro­cess­ing areas in the supe­ri­or tem­po­ral and prefrontal/frontal cortex.

We ten­ta­tive­ly have termed this process “upstream del­e­ga­tion”. We have also tried and estab­lished a slight­ly unusu­al method to do jus­tice to the fMRI acti­va­tion data: We have includ­ed all z‑scores gath­ered along cer­tain spa­tial dimen­sions, irre­spec­tive of whether they were sub- or suprathresh­old, and have treat­ed them as dis­tri­b­u­tions. Check it out and let us know what you think.

Ref­er­ences

  • Obleser J, Mey­er L, Friederi­ci AD. Dynam­ic assign­ment of neur­al resources in audi­to­ry com­pre­hen­sion of com­plex sen­tences. Neu­roim­age. 2011 Jun 15;56(4):2310–20. PMID: 21421059. [Open with Read]