Coding of auditory signals in narrowband neurons in the inferior colliculus of the barn owl [Elektronische Ressource] / Martin Singheiser

Martin Luther

Sujets

• Biologie

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2011
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 19 Mo

Extrait

Coding of Auditory Signals
in Narrowband Neurons in the
Inferior Colliculus of the Barn Owl

Von der Fakultät für Mathematik, Informatik und Naturwissenschaften der
RWTH Aachen University
zur Erlangung des akademischen Grades
eines Doktors der Naturwissenschaften
genehmigte Dissertation

vorgelegt von
Diplom-Biologe
Martin Singheiser
aus Erlangen

Berichter: Universitätsprofessor Dr. Hermann Wagner
Universitätsprofessor Dr. Marc Spehr

Tag der mündlichen Prüfung: 20.05.2011

Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.
























2 Contents
List of Figures 4
List of Tables 5
Nomenclature 6
1 Summary 8
2 Zusammenfassung 10
3 General Introduction 12
3.1 Sound localization in the barn owl 12
3.2 The auditory pathway 13
3.3 The inferior colliculus of the barn owl 15
3.4 Aim of the thesis 16
4 The Stereausis Model – an Alternative Coding Mechanism for ITDs? 18
4.1 Introduction 18
4.2 Methods 20
4.2.1 Owl handling and surgery 20
4.2.2 Signal generation and data acquisition 21
4.2.3 Stimulation protocol 21
4.2.4 Physiological characterization of the location of recording 22
4.2.5 Data analysis 22
4.2.6 Computational model 22
4.3 Results 24
4.3.1 General response properties 24
4.3.2 Distribution of best ITDs 25
4.3.3 Measures and distribution of best frequenc 26
4.3.4 Comparison of single and multi units 27
4.3.5 Frequency tuning width and best frequency 28
4.3.6 Relationship of ITD on frequency tuning width 29
4.3.7 Frequency mismatch between contralateral and ipsilateral inputs 30
4.3.8 Implications of the stereausis model 32
4.3.9 Comparison of frequency mismatches 33
4.4 Discussion 34
4.4.1 ITD and frequency tuning 34
4.4.2 Distribution of best ITDs 35
4.4.3 Measures and distribution of best frequenc 36


3 5 Adaptation in Narrowband Neurons in the Inferior Colliculus 37
5.1 Introduction 37
5.2 Methods 38
5.2.1 Owl handling 38
5.2.2 Signal generation and data acquisition 38
5.2.3 Stimulation protocol for physiological characterization of the recording site 39
5.2.4 Stimulation protocol to test for adaptation 40
5.2.5 Data analysis 42
5.3 Results 46
5.3.1 General response properties – frequency tuning 46
5.3.2 General response properties – rate-level-functions 48
5.3.3 Response adaptation in ICC neurons 51
5.3.4 Spike-frequency adaptation in ICC neurons 65
nd5.3.5 Comparison of τ and AR between the 2 level and ISI tuning 86
5.4 Discussion 88
5.4.1 Frequency tuning 88
5.4.2 Rate-level functions and spontaneous ratios 89
5.4.3 Response adaptation quantified by the response ratio 90
5.4.4 Response adaptation quantified by the masking ratio 92
5.4.5 Comparison of the recovery from response adaptation 93
5.4.6 Spike-frequency adaptation of the responses to the masker 94
5.4.7 Spike-frequency adaptation of the responses to the probe 96
5.4.8 The role of adaptation in the computation of auditory space 98
5.4.9 The role of adaptation in sound level coding 99
5.4.10 Mechanisms of adaptation 100
5.4.11 Conclusion 100
6 General Discussion 102
6.1 ITD coding in barn owls and mammals 102
6.2 The role of the ICC in sound localization 105
7 Bibliography 108
8 Acknowledgements 118
9 Curriculum Vitae 119





4 List of Figures

Figure 1 Auditory pathway 14
Figure 2 Stereausis model 19
Figure 3 Cochlar and neural delays 24
Figure 4 Examples of tuning curves 25
Figure 5 Distributions of array-specific ITDs and best frequencies 26
Figure 6 Response rates and latencies of frequency tunings 27
Figure 7 Relationship of W and BF 29 50 50
Figure 8 Effect of array-specific ITD on W 30 50
Figure 9 Relationship between ipsilateral and contralateral inputs 31
Figure 10 Frequency mismatch in ICCcore neurons 31
Figure 11 Comparison of the data with the stereausis model 32
Figure 12 Frequency mismatches 34
Figure 13 Exemplary tuning curves 40
ndFigure 14 Exemplary 2 level tunings 41
Figure 15 Exemplary ISI tunings 42
Figure 16 Computation of the masking ratio 44
Figure 17 Computation of the time contant τ and the adaptation ratio 45
Figure 18 Frequency tuning in ICC 47
Figure 19 Rate-level functions in ICC 49
Figure 20 Spontaneous ratio 50
ndFigure 21 Response ratios in the 2 level tuning 52
Figure 22 Relationship of response ratio and masker level 53
ndFigure 23 Compensation of the response ratios in the 2 level tuning 54
Figure 24 Relationship of response ratio and BF 56 50
Figure 25 Response ratios in the ISI tuning 58
Figure 26 Response ratios and recovery from adaptation in the ISI tuning 59
ndFigure 27 Comparison of the 2 level and ISI tuning 60
Figure 28 Masking ratios in the ISI tuning 62
Figure 29 PSTHs for pooled masker responses 65
ndFigure 30 Masker time constants and adaptation ratios in the 2 level tuning 67
Figure 31 SFA for the responses to masker and probe 68
Figure 32 Probe time constants and adaptation ratios at 50% masker level 69
ndFigure 33 Cumulative probability distributions for the probe responses in the 2 level tuning 71
ndFigure 34 Summary of the time constants and adaptation ratios in the 2 level tuning 72
5 ndFigure 35 Time constants in the 2 level tuning 73
ndFigure 36 Relationship of time constant and masker level in the 2 level tuning 74
ndFigure 37 Adaptation ratios in the 2 level tuning 75
ndFigure 38 Relationship of adaptation ratio and masker level in the 2 level tuning 76
Figure 39 Masker time constants and adaptation ratios in the ISI tuning 78
Figure 40 Cumulative probabilities of time constants and adaptation ratios in the ISI tuning 79
Figure 41 Summary of the time constants and adaptation ratios in the ISI tuning 81
Figure 42 Time constants in the ISI tuning 82
Figure 43 Relationship of time constant and masker level in the ISI tuning 83
Figure 44 Adaptation ratios in the ISI tuning 84
Figure 45 Relationship of adaptation ratio and masker level in the ISI tuning 85
ndFigure 46 Comparison of τ and AR between the 2 level and ISI tuning 87




List of Tables

ndTable 1 Compensation in the 2 level tuning 55
ndTable 2 Comparison of response compensation in the 2 level tuning 56
Table 3 Compensation in the ISI tuning 63
Table 4 Comparison of the recovery time constants 64
ndTable 5 Linear regressions for the time constants in the 2 level tuning 75
ndTable 6 Linear regressions for the adaptation ratios in the 2 level tuning 77
Table 7 Linear regressions for the time constants in the ISI tuning 83
Table 8 Linear regressions for the adaptation ratios in the ISI tuning 85







6 Nomenclature

AAr auditory arcopallium
AN auditory nerve
ANN auditory nerve neurophonic
AR adaptation ratio
BF best frequency
BF center frequency at half maximum width of the FTC 50
CF center frequency
FTC frequency tuning curve
IC inferior colliculus
ICC central nucleus of the inferior colliculus
ICCcore core of the central nucleus of the inferior colliculus
ICCls lateral shell of the central nucleus of the inferior colliculus
ICX external nucleus of the inferior colliculus
ILD interaural level difference
ITD interaural time difference
LLDa anterior part of the dorsolateral lemniscal nucleus
LLDp posterior part of the dorsolateral lemniscal nucleus
LSO lateral superior olive
MR masking ratio
MSO medial superior olive
NA nucleus angularis
NL nucleus laminaris
NM nucleus magnocellularis
NO nucleus ovoidalis
OT optic tectum
PSTH peri-stimulus-time-histogram
RLF rate-level function
RR response ratio
SD standard deviation
SEM standard error of the mean
SFA spike-frequency adaptation
SR spontaneous ratio
τ time constant
W bandwidth of a FTC at half maximum rate 50
7 1 Summary

The barn owl (Tyto alba) is a well-known model system for auditory processing and sound localizati