What underlies between-frequency gap detection? Shuji Mori Kyushu University 2014 Symposium on Across-Channel Processing in Human Audition Niagara-on-the-lake, Canada, 2014/08/06
‘What’ and ‘Where’ What makes BF gap detection so difficult? Across-channel processing Relative timing/attention shift Channel bandwidth Onset cue Where in auditory pathway does it take place? Peripheral Central Primary auditory cortex 1 Psychophysics Lab. Department of Informatics Faculty of ISEE
Relative timing Monitoring offset of leading and onset of trailing marker (Phillips, 1999) Reflects central processes Discontinuity detection Performed peripherally 2 Psychophysics Lab. Department of Informatics Faculty of ISEE
Attention shift Auditory attention Directed to frequency channel (attention band; Scharf et al., 1987) Enhances auditory processing Two hypotheses 1. Attention dwell time (Fitzgibbons et al., 1974) Minimum time spent at one channel before shifting to another channel 2. Attention disruption (Phillips et al., 1997) Imprecise time-stamping when shifting to unattended channel Can be differentiated in terms of psychometric function (Kikuchi et al., 2014) 3 Psychophysics Lab. Department of Informatics Faculty of ISEE
Psychometric function Within-frequency 1.0 ‘Yes’ responses (Florentine et al., Proportion of 1990) 0.5 Between-frequency Attention disrupt. Dwell time 0 0 1 10 100 Gap duration (msec) Internal noise 4 Psychophysics Lab. Department of Informatics Faculty of ISEE
Kikuchi et al. (2014) 1.0 1.0 P1 P2 0.80 0.80 0.60 0.60 P y P y 0.40 0.40 0.20 0.20 0.0 0.0 0.1 1 10 100 0.1 1 10 100 Gap duration (msec) Gap duration (msec) 1.0 800-800 P3 800-1600 0.80 1600-800 0.60 800-3200 P y 3200-800 0.40 0.20 0.0 0.1 1 10 100 Gap duration (msec) 5 Psychophysics Lab. Department of Informatics Faculty of ISEE
Problems on attention shift Attention shifts instantaneously (Scharf et al., 2007) Attention can be directed to multiple frequencies (Schlauch & Hafter, 1991) No study yet to manipulate attention in BF gap detection 6 Psychophysics Lab. Department of Informatics Faculty of ISEE
Channel bandwidth Formby & Forrest (1991) Estimate channel bandwidth from BF gap detection (Adapted from Formby & Forrest, 1991, p.836, Fig.4) (Formby & Forrest, 1991, p.834, Fig.3) About half of bandwidth of typical auditory filters (e.g. Patterson & Moore, 1986) 7 Psychophysics Lab. Department of Informatics Faculty of ISEE
Channel bandwidth Single- and multiple-channel models (Forrest & Formby, 1996; Heinz et al., 1996) (Forrest & Formby, 1996, p.24, FIGURE 1) 8 Psychophysics Lab. Department of Informatics Faculty of ISEE
Channel bandwidth Single- and multiple-channel models (Forrest & Formby, 1996; Heinz et al., 1996) (Forrest & Formby, 1996, p.29, FIGURE 5) Gap thresholds reflect narrowed channel bandwidth 9 Psychophysics Lab. Department of Informatics Faculty of ISEE
Problems on bandwidth account No explanation of why channel is narrowed under BF gap detection Empirical evidence lacking for effect of bandwidth on gap detection 10 Psychophysics Lab. Department of Informatics Faculty of ISEE
Trailing marker onset WF onset Amplitude Time Can be accomplished by onset detection (≈discontinuity detection) BF onset Amplitude onset Time Onset cue unreliable 11 Psychophysics Lab. Department of Informatics Faculty of ISEE
Onset account Availability of TM onset cue distinguishes between WF and BF gap detection Neuronal onset responses match WF gap detection Werner et al. (2001) (Werner et al., 2001, p.741, Figures 2 and 3) 12 Psychophysics Lab. Department of Informatics Faculty of ISEE
Onset account Reducing onset-cue availability impairs gap detection Oxenham (2000) Inducing amplitude difference to two WF markers Amplitude Time Worsens gap detection to BF level Grose et al. (2007) Presenting secondary tone with TM worsens BF gap detection TM onset obscured by the tone 13 Psychophysics Lab. Department of Informatics Faculty of ISEE
Onset account Eggermont (2000) Single-cell recording at cat auditory cortex Manipulating LM duration (Eggermont, 2010, pp.1458, Fig.6; pp.1459, Fig.7) TM onset responses appear 40-55 ms after LM onset Corresponds to behavioral data (Phillips et al., 1997) 14 Psychophysics Lab. Department of Informatics Faculty of ISEE
Problems on onset account Only explains qualitative categorical difference between WF and BF Unable to deal with frequency separation effects on BF gap detection (Phillips et al., 1997, JASA, pp.3697, Fig.2) 15 Psychophysics Lab. Department of Informatics Faculty of ISEE
‘Where’ in auditory pathway Peripheral Auditory filter (Formby & Forrest, 1991; Forrest & Formby, 1996) Central Channel monitoring (Phillips et al., 1997) Attentional operation (Fitzgibbons et al., 1974) Primary auditory cortex • Broadly-tuned onset-sensitive neurons (Eggermont, 2000) • Comparable MMN for WF and BF generated near PAC (Heinrich et al., 2004) • Frequency-separate regions of onset responses (Mitsudo, Hironaga) 16 Psychophysics Lab. Department of Informatics Faculty of ISEE
Our approach Psychophysics 1.0 0.80 0.60 P y 0.40 0.20 0.0 MEG 0.1 1 10 100 Gap duration (msec) ABR (Coren et al., 1994, Sensation & perception, pp.204, Fig.6-17) 17 Psychophysics Lab. Department of Informatics Faculty of ISEE
Auditory brainstem response Reflects onset responses of auditory nerves and brainstem neurons Mostly measured to WF TM onset Werner et al., 2001; Poth et al., 2001 Grose et al. (2007) Measured ABR to BF TM onset consisting of two-tone complex 18 Psychophysics Lab. Department of Informatics Faculty of ISEE
Method Participants 10 healthy male students (mean 22.9 yrs) Stimuli LM & TM – 0.5-oct. bandnoise of 50 ms (rise/fall 3 ms) 45 dB SPL monaurally presented to left ear LM/TM center frequency (Hz): 800/800, 800/1600, 1600/800, 800/3200, 3200/800 No gap Gap duration 19 Psychophysics Lab. Department of Informatics Faculty of ISEE
Method Procedure threshold measurement 2IFC 1-up 6-down procedure to obtain 89.1% accuracy gap thresholds 30 25 Gap Threshold (ms) 20 15 10 5 0 800/800 800/1600 1600/800 800/3200 3200/800 LM/TM Frequency (Hz) 20 Psychophysics Lab. Department of Informatics Faculty of ISEE
Method ABR measurement Gap durations set to 0 (no gap), and 0.5, 1.0, and 1.5 times of individual gap thresholds for each LM/TM frequency 2000 presentations for each gap/frequency at 3-Hz rate Recorded at Cz with a reference at A2 and a ground at Fpz Band-pass filtering between 100 and 3000 Hz 100 kHz sampling rate 21 Psychophysics Lab. Department of Informatics Faculty of ISEE
Method Amplitudes and latencies extracted from individual ground averages Wave V TM onset Latency Amplitude 0.1μV 5msec 22 Psychophysics Lab. Department of Informatics Faculty of ISEE
Results Mean amplitudes and latencies of 10 ps 800/800 800/1600 800/3200 800/800 800/1600 800/3200 0.18 15 1600/800 3200/800 1600/800 3200/800 0.16 Amplitude (microV) 14 Latency (msec) 0.14 13 0.12 0.1 12 0.08 11 0.06 0.5T T 1.5T 0 0.5T T 1.5T 0 0.5T T 1.5T 0.5T T 1.5T 0 0.5T T 1.5T 0 0.5T T 1.5T Gap Condition Gap Condition 23 Psychophysics Lab. Department of Informatics Faculty of ISEE
Results Mean amplitudes as a function of gap duration in ms 0.18 800/800 800/1600 800/3200 1600/800 3200/800 0.16 Amplitude (microV) 0.14 6~7 ms + 50-ms LM duration 0.12 ≈ 55-ms from LM onset 0.1 0.08 0.06 0 5 10 15 20 25 30 35 Gap Duration (ms) 24 Psychophysics Lab. Department of Informatics Faculty of ISEE
Discussion Increased ABR amplitude (TM onset response?) at ~ 55 ms after LM onset TM onset responses appear 40-55 ms after LM onset (Eggermont) (Eggermont, 2010, pp.1459, Fig.7) 25 Psychophysics Lab. Department of Informatics Faculty of ISEE
Discussion ABR to TM onset reflects physical duration rather than psychophysical threshold TM onset response is not a sole determinant of gap threshold Very high accuracy (89.1%) of gap detection criterion may contribute to the discrepancy LM duration needs to be manipulated ABR reflects broadly tuned mechanism Low (suppressed?) ABR observed for BF below 55 ms 26 Psychophysics Lab. Department of Informatics Faculty of ISEE
Conclusion What makes BF gap detection so difficult? Unavailability of TM onset cue Other processes to be identified for frequency separation effect Where in auditory pathway does it take place? As early as brainstem for onset cue Primary auditory cortex Peripheral? 27 Psychophysics Lab. Department of Informatics Faculty of ISEE
Comprehensive approach Psychophysics 1.0 0.80 0.60 P y 0.40 0.20 0.0 MEG 0.1 1 10 100 Gap duration (msec) ABR DSAM simulations (Coren et al., 1994, Sensation & perception, pp.204, Fig.6-17) 28 Psychophysics Lab. Department of Informatics Faculty of ISEE
Currently ongoing… BF gap detection with close frequency separation 1.0 0.80 0.60 P y 800/800 0.40 800/830 0.20 800/880 800/1000 0.0 0 10 20 30 40 Gap duration (msec) Followed by MEG, ABR, and DSAM 29 Psychophysics Lab. Department of Informatics Faculty of ISEE
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