New paper in Neu­roim­age by Fiedler et al.: Track­ing ignored speech mat­ters

Lis­ten­ing requires selec­tive neur­al pro­cess­ing of the incom­ing sound mix­ture, which in humans is borne out by a sur­pris­ing­ly clean rep­re­sen­ta­tion of attend­ed-only speech in audi­to­ry cor­tex. How this neur­al selec­tiv­i­ty is achieved even at neg­a­tive sig­nal-to-noise ratios (SNR) remains unclear. We show that, under such con­di­tions, a late cor­ti­cal rep­re­sen­ta­tion (i.e., neur­al track­ing) of the ignored acoustic sig­nal is key to suc­cess­ful sep­a­ra­tion of attend­ed and dis­tract­ing talk­ers (i.e., neur­al selec­tiv­i­ty). We record­ed and mod­eled the elec­troen­cephalo­graph­ic response of 18 par­tic­i­pants who attend­ed to one of two simul­ta­ne­ous­ly pre­sent­ed sto­ries, while the SNR between the two talk­ers var­ied dynam­i­cal­ly between +6 and −6 dB. The neur­al track­ing showed an increas­ing ear­ly-to-late atten­tion-biased selec­tiv­i­ty. Impor­tant­ly, acousti­cal­ly dom­i­nant (i.e., loud­er) ignored talk­ers were tracked neu­ral­ly by late involve­ment of fron­to-pari­etal regions, which con­tributed to enhanced neur­al selec­tiv­i­ty. This neur­al selec­tiv­i­ty, by way of rep­re­sent­ing the ignored talk­er, pos­es a mech­a­nis­tic neur­al account of atten­tion under real-life acoustic con­di­tions.

The paper is avail­able here.

14. November 2018 by Jonathan Mortensen
Categories: Attention, Auditory Cortex, Auditory Neuroscience, EEG / MEG, Papers, Perception, Psychology, 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.

29. October 2018 by Jonathan Mortensen
Categories: Auditory Cortex, EEG / MEG, 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

 

21. September 2018 by Jonathan Mortensen
Categories: Attention, Auditory Cortex, Brain stimulation, Papers, Perception, Publications |

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 –

12. July 2018 by Jonas
Categories: Adaptive Control, Auditory Cortex, Auditory Neuroscience, Auditory Working Memory, Neural Oscillations, Papers, Perception, Psychology, Uncategorized |

New paper in Ear and Hear­ing: Erb, Lud­wig, Kunke, Fuchs & Obleser on speech com­pre­hen­sion with a cochlear implant

We are excit­ed to share the results from our col­lab­o­ra­tion with the Cochlea Implant Cen­ter Leipzig: AC post­doc Julia Erb’s new paper on how 4-Hz mod­u­la­tion sen­si­tiv­i­ty can inform us on 6-month speech com­pre­hen­sion out­come in cochlear implants.

Erb J, Lud­wig AA, Kunke D, Fuchs M, & Obleser J (2018). Tem­po­ral sen­si­tiv­i­ty mea­sured short­ly after cochlear implan­ta­tion pre­dicts six-month speech recog­ni­tion out­come

Now avail­able online:

https://insights.ovid.com/crossref?an=00003446–900000000-98942

Abstract:

Objec­tives:

Psy­choa­coustic tests assessed short­ly after cochlear implan­ta­tion are use­ful pre­dic­tors of the reha­bil­i­ta­tive speech out­come. While large­ly inde­pen­dent, both spec­tral and tem­po­ral res­o­lu­tion tests are impor­tant to pro­vide an accu­rate pre­dic­tion of speech recog­ni­tion. How­ev­er, rapid tests of tem­po­ral sen­si­tiv­i­ty are cur­rent­ly lack­ing. Here, we pro­pose a sim­ple ampli­tude mod­u­la­tion rate dis­crim­i­na­tion (AMRD) par­a­digm that is val­i­dat­ed by pre­dict­ing future speech recog­ni­tion in adult cochlear implant (CI) patients.

Design:

In 34 new­ly implant­ed patients, we used an adap­tive AMRD par­a­digm, where broad­band noise was mod­u­lat­ed at the speech-rel­e­vant rate of ~4 Hz. In a lon­gi­tu­di­nal study, speech recog­ni­tion in qui­et was assessed using the closed-set Freiburg­er num­ber test short­ly after cochlear implan­ta­tion (t0) as well as the open-set Freiburg­er mono­syl­lab­ic word test 6 months lat­er (t6).

Results:

Both AMRD thresh­olds at t0 (r = –0.51) and speech recog­ni­tion scores at t0 (r = 0.56) pre­dict­ed speech recog­ni­tion scores at t6. How­ev­er, AMRD and speech recog­ni­tion at t0 were uncor­re­lat­ed, sug­gest­ing that those mea­sures cap­ture par­tial­ly dis­tinct per­cep­tu­al abil­i­ties. A mul­ti­ple regres­sion mod­el pre­dict­ing 6-month speech recog­ni­tion out­come with deaf­ness dura­tion and speech recog­ni­tion at t0 improved from adjust­ed R2 = 0.30 to adjust­ed R2 = 0.44 when AMRD thresh­old was added as a pre­dic­tor.

Con­clu­sions:

These find­ings iden­ti­fy AMRD thresh­olds as a reli­able, nonre­dun­dant pre­dic­tor above and beyond estab­lished speech tests for CI out­come. This AMRD test could poten­tial­ly be devel­oped into a rapid clin­i­cal tem­po­ral-res­o­lu­tion test to be inte­grat­ed into the post­op­er­a­tive test bat­tery to improve the reli­a­bil­i­ty of speech out­come prog­no­sis.

 

05. June 2018 by Jonathan Mortensen
Categories: Auditory Cortex, Auditory Perception, Auditory Speech Processing, Hearing Loss, Papers, Perception, Publications, Speech |

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