CNBH, PDN, University of Cambridge Part II: Lent Term 2015: ( 4 of 4) Central Auditory Processing Roy Patterson Centre for the Neural Basis of Hearing Department of Physiology, Development and Neuroscience University of Cambridge email rdp1@cam.ac.uk Lecture slides on CamTools https://camtools.cam.ac.uk/portal.html Lecture slides, sounds and background papers on http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/ CNBH, PDN, University of Cambridge Contents/Progress Act I: Communication sounds and the information in these sounds: message, Ss and Sf Act II: Behavioural evidence for the role of these different forms of information in the perception of communication sounds Act III: The processing of communication sounds in the early stages of the auditory system, and hypotheses about the representation of communication sounds in later stages of the auditory pathway Act IV: Brain imaging evidence concerning the representation of communication sounds in auditory cortex CNBH, PDN, University of Cambridge We have discussed a model of auditory perception that describes how sounds might be processed and represented at a sequence of stages in auditory system. All of the stages are mandatory and the order is crucial. One representation is intended to simulate your initial Auditory Image of the incoming sound and it is central to the model. Sensations like pitch and loudness are summary statistics calculated from the auditory image after it has been constructed. Speech and music perception are thought to be based on the patterns that arise in the auditory image. So, this Auditory Image Model (AIM) predicts that we should find a hierarchy of processing modules in the auditory pathway. CNBH, PDN, University of Cambridge There is a sequence of neural centres in the auditory pathway. Overviewhierarchy. 2 It looks like it could be a processing The centres are separated by distances that are large relative the resolution of functional brain imaging (fMRI). LL LL The correspondence between the perceptual model and the anatomy suggests that (1) AIM could be useful when designing brain imaging studies of the auditory system and (2) the brain imaging data could help us locate the auditory image. CNBH, PDN, University of Cambridge Basilar membrane motion in the cochlea Anatomy of the Auditory Pathway: 1 CNBH, PDN, University of Cambridge Neural activity pattern in the cochlear nucleus CNBH, PDN, University of Cambridge Strobed temporal integration in the inferior colliculus? CNBH, PDN, University of Cambridge The initial auditory image in the MGB?? CNBH, PDN, University of Cambridge Auditory Image The normalized auditory image in primary auditory cortex??? CNBH, PDN, University of Cambridge The Auditory Image Model describes how the auditory system separates pulse-resonance sounds from noise, and how it normalizes and segregates the information about the pulse-rate (Ss) and the resonance scale (Sf ) from the message. So the brain imaging research focuses on finding evidence that the neural centres in the auditory pathway are involved in source segregation and normalization, and that the segregation and pulserate normalization come before the resonance scale normalization. Moreover, speech-specific analysis and music-specific analysis should occur in neural centres beyond, but not too far from, those associated with segregation of pulseresonance sounds from noise and their normalization. CNBH, PDN, University of Cambridge Brain Imaging with Simple Contrasts Find two sounds that differ only in the perceptual property of interest (like pitch). Scan the brain while people are listening, first to one sound and then to the other sound. Compare the brain activity produced by the two sounds looking for places where one sound produces more activity than the other. CNBH, PDN, University of Cambridge Brain imaging with Regular Interval Noise Copy a sample of random noise; delay it by N ms; add it to the original noise. The process emphasises time intervals of N ms in the sound and we hear a weak tone in the noise. As you repeat the delay and add process, the relative strength of the tonal component of the sound increases. RIN makes a good imaging stimulus because the sounds have similar distributions of energy over time and frequency. In the experiment the RIN had 8 iterations of the delay and add process. CNBH, PDN, University of Cambridge A B Auditory Image Noise D F RIN J G Neural activity patterns of Noise and RIN CNBH, PDN, University of Cambridge B C E G H K Initial auditory images of noise and RIN CNBH, PDN, University of Cambridge Continuous Imaging vs Sparse Imaging continuous imaging sparse imaging haemodynamic response to test stimulus haemodynamic response to scanner noise Difference in sensitivity to stimulus: positive negative [original figure by D. Hall, IHR, Nottingham] CNBH, PDN, University of Cambridge Imaging pitch and melody in the brain On a given scan, the listener is presented a sound with a pulsing rhythm. The sound has no pitch (a noise), a fixed pitch (boring melody) or changing pitch (proper melody). Asked to listen for pattern in the sound, but no response is required. http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/PUJG02.pdf CNBH, PDN, University of Cambridge CN T value IC CN Parasagital view showing CN/ IC AC AC IC Axial view at level CN AC AC MGB 40 35 30 25 20 15 10 5 0 CN Coronal view showing IC Coronal view showing MGB + superior temporal lobe + superior temporal lobe Griffiths et al. Nature Neuroscience (2001) Sound minus silence contrast CNBH, PDN, University of Cambridge Left Hemisphere axial coronal Group Analysis noise-silence fixed-noise diatonic-fixed random-fixed structural -78 -10 34.4° axial saggital structural coronal 10 78 Patterson, Uppenkamp, Johnsrude and Griffiths (2002) saggital Right Hemisphere x 34.4° Figure 2 saggital axial coronal Group analysis noise-silence fixed-noise tonic-fixed random-fixed structural axial saggital structural coronal Patterson, Uppenkamp, Johnsrude and Griffiths (2002) CNBH, PDN, University of Cambridge x -78 -10 34.4° 10 78 34.4° regular strong pitch equal energy click trains Neural Activity Pattern Auditory Image irregular no pitch Gutschalk, Patterson, Scherg, Uppenkamp, and Rupp, (2002) CNBH, PDN, University of Cambridge CNBH, PDN, University of Cambridge posterior source: PT Effects of regularity and intensity in MEG effect of regularity in anterior source effect of level in posterior source Gutschalk, Patterson, Scherg, Uppenkamp, and Rupp, (2002) anterior source: HG CNBH, PDN, University of Cambridge Conjecture Conjecture Conjecture Proposed functional organisation of auditory cortex all sounds primary auditory cortex auditory cortex tonal sounds loudness lively pitch fixed pitch lively pitch CNBH, PDN, University of Cambridge http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/PUJG02.pdf http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/GPRUS02.pdf Where does the auditory system segregate the information associated with Ss, Sf and the message? CNBH, PDN, University of Cambridge A damped sinusoid (12-ms period) pulse ringing CNBH, PDN, University of Cambridge Auditory image of a damped sinusoid 6000 Hz pulse 1000 Hz ringing 100 Hz CNBH, PDN, University of Cambridge Stimuli for Phonology Study formant frequencies regular irregular regular onset timing irregular CNBH, PDN, University of Cambridge Comparison of speech and music regions z = 4mm z = 4mm mpmr-silence nvdvpv-mpmr mpmr-nvdvpv noise-silence fixed-noise lively-fixed y = -24mm y = -17mm z = -5mm z = -5mm CNBH, PDN, University of Cambridge Left Hemisphere saggital Right Hemisphere axial saggital axial pitch vtl AudIm coronal phonology Group analysis noise-silence fixed-noise tonic-fixed random-fixed structural coronalphonology structural x -78 -10 34.4° 10 78 34.4° CNBH, PDN, University of Cambridge Conjecture Conjecture Conjecture Proposed functional organisation of auditory cortex all sounds primary auditory cortex auditory cortex tonal sounds loudness lively pitch fixed pitch receptive phonology lively pitch CNBH, PDN, University of Cambridge Done! Act I: the information in communication sounds (animal calls, speech, musical notes) Act II: the perception of communication sounds (the robustness of perception) Act III: the processing of communication sounds in the auditory system (signal processing) Act IV: the processing of communication sounds (anatomy, physiology, brain imaging) CNBH, PDN, University of Cambridge End of Act IV Thank you Patterson, R.D., Uppenkamp, S., Johnsrude, I. and Griffiths, T. D. (2002). The processing of temporal pitch and melody information in auditory cortex. Neuron 36 767-776. http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/PUJG02.pdf Gutschalk, A., Patterson, R.D., Rupp, A., Uppenkamp, S. and Scherg, M. (2002). Sustained magnetic fields reveal separate sites for sound level and temporal regularity in human auditory cortex. NeuroImage 15 207-216. http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/GPRUS02.pdf Kriegstein, K. Von, Smith, D. R. R., Patterson, R. D., Kiebel, S. J. and Griffiths, T. D. (2010). “How the human brain recognizes speech in the context of changing speakers,”J. Neuroscience 30(2) 629–638. http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/KSPKGjn2010.pdf CNBH, PDN, University of Cambridge Cast list Roy Patterson, David Smith, Tim Ives, Ralph van Dinther Centre for the Neural Basis of Hearing, Physiology Department, University of Cambridge fMRI in Cambridge: Ingrid Johnsrude, Dennis Norris, Matt Davis, Alexis Hervais-Adelman, William Marslen-Wilson MRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge MEG in Heidelberg: Andre Rupp, Alexander Gutschalk, Stefan Uppenkamp, Michael Scherg MEG in Muenster: Katrin Krumbholz, Annemarie Preisler, Bernd Lutkenhoner CNBH, PDN, University of Cambridge Activation of voiced vs whispered speech x=+51 signal change (%) *** L *** *** TE1.2 TE1.1 y=-2 voiced > whispered whispered > voiced GPR varies > VTL varies voiced > silence whispered > silence CNBH, PDN, University of Cambridge coronal Group analysis noise-silence fixed-noise tonic-fixed random-fixed Conjecture axial axial structural Conjecture saggital structural Patterson, Uppenkamp, Johnsrude and Griffiths (2002) Conjecture saggital coronal x -78 -10 34.4° 10 78 34.4° CNBH, PDN, University of Cambridge coronal Group analysis noise-silence fixed-noise tonic-fixed random-fixed Conjecture axial axial structural Conjecture saggital structural Patterson, Uppenkamp, Johnsrude and Griffiths (2002) Conjecture saggital coronal x -78 -10 34.4° 10 78 34.4°