Encoding and attentive modulation of dynamic motion stimuli [Elektronische Ressource] / vorgelegt von Heiko Stemmann

Heiko Stemmann

Sujets

• Biologie

Informations

• Publié par: universitat_bremen
• Publié le: 01 janvier 2008
• Nombre de lectures: 24
• Langue: English
• Poids de l'ouvrage: 43 Mo

Extrait

Encoding and Attentive Modulation of Dynamic Motion
Stimuli
Dissertation
zur Erlangung des Grades eines Doktors
der Naturwissenschaften
vorgelegt von
Heiko Stemmann
Institut für Hirnforschung
Fachbereich 2
Universität Bremen
Bremen, November 2008 ii1. Gutachter: Prof. Dr. Manfred Fahle
2. Gutachter: Prof. Dr. Michael Koch
iiiTable of Contents
1 Table of Contents
2 Introduction....................................................................................................................... 1
2.1 The Receptive Field.............................................................................................................1
2.2 Linear Receptive Field Models...........................................................................................2
2.3 Direction selectivity in Macaque visual area MT..............................................................3
2.4 Investigating the Encoding of Stimulus Features by Reconstruction..............................7
2.5 Attentive Modulation of Neural Response Behaviour......................................................8
2.6 A network perspective on effects of attention on cortical motion processing...............13
3 Overview of experiments ................................................................................................. 15
4 Encoding of dynamic visual stimuli by primate area MT neurons ............................... 16
4.1 Abstract .............................................................................................................................16
4.2 Introduction.......................................................................................................................16
4.3 Methods .............................................................................................................................16
4.4 Results...........19
4.5 Discussion ..........................................................................................................................21
5 Linearity of Macaque Area MT Neurons: Model-based Interpretation of Population
Responses to Dynamic Motion Stimuli................................................................................... 23
5.1 Introduction.......................................................................................................................23
5.2 Materials and Methods.....................................................................................................24
5.2.1 Recording and Surgical Techniques............................................................................................... 24
5.2.2 Behavioural Task and Visual Stimulation... 24
5.2.3 Data Analysis.................................................................................................................................. 26
5.2.4 Reconstruction of Movement Directions........................................................................................ 31
5.2.5 Model Simulations.......................................................................................................................... 33
5.3 Results................................................................................................................................34
5.3.1 Spike–Triggered Averages and Latencies ...................................................................................... 34
5.3.2 Tuning Curves ................................................................................................................................ 36
5.3.3 Linear Filter Estimates from Continuous and Discontinuous Stimulation..................................... 39
5.3.4 Stimulus Reconstruction................................................................................................................. 42
5.3.5 Comparison of MAP and ML Reconstructions .............................................................................. 43
5.3.6 Temporal Stimulus Statistics and Reconstruction Accuracy.......................................................... 44
5.3.7 Coding Strategies for Dynamic Stimulus Trajectories................................................................... 47
5.3.8 Time Integration of Stimulus Representation for Neural Populations ........................................... 48
5.4 Discussion ..........................................................................................................................50
5.4.1 Delays ............................................................................................................................................. 50
5.4.2 Tuning Curves ................................................................................................................................ 51
5.4.3 Linear Filters .................................................................................................................................. 52
5.4.4 Reconstruction – Comparison of MAP and ML Estimates ............................................................ 52
ivTable of Contents
5.4.5 Reconstruction – Stimulus Statistics .............................................................................................. 54
5.4.6 Reconstruction – Coding Strategies for Dynamic Stimulus Trajectories....................................... 54
5.4.7 Reconstruction – Time Course of Stimulus Representation for Neural Populations ..................... 55
5.5 Final Conclusions..............................................................................................................55
6 Effects of Attention during Rapid Serial Visual Presentation on Macaque MT
Neurons.................................................................................................................................... 56
6.1 Introduction.......................................................................................................................56
6.2 Methods .............................................................................................................................56
6.2.1 Animals and surgical procedures.................................................................................................... 56
6.2.2 Data acquisition and recording....................................................................................................... 56
6.2.3 Behavioural task and visual stimulation......................................................................................... 57
6.2.4 Data Analysis.................................................................................................................................. 58
6.3 Results...........59
6.3.1 Behaviour ....................................................................................................................................... 59
6.3.2 Neural responses............................................................................................................................. 59
6.4 Discussion and Conclusion ...............................................................................................62
7 Imaging Cortical Networks of Spatial Attention in the Macaque................................. 63
7.1 Introduction.......................................................................................................................63
7.2 Methods .............................................................................................................................64
7.3 Results...........69
7.4 Discussion ..........................................................................................................................76
7.5 Appendix............................................................................................................................78
7.5.1 Behavioral Performance ................................................................................................................. 78
7.5.2 Functional Brain Maps ................................................................................................................... 81
7.5.3 Reaction times ................................................................................................................................ 83
8 Conclusion... 85
9 Summary / Zusammenfassung ....................................................................................... 87
9.1 Summary ...........................................................................................................................87
9.2 Zusammenfassung.............................................................................................................88
10 Acknowledgements .......................................................................................................... 90
11 References........................................................................................................................ 92
vIntroduction
2 Introduction
2.1 The Receptive Field
How much do we understand about processing in early visual areas of the brain? Several
recent publications have asked this question (Carandini, Demb et al. 2005; Olshausen and
Field 2005), showing that after decades of research our understanding is still not complete.
Since the seminal findings of Hubel and Wiesel in cat (Hubel and Wiesel 1959) and primate
primary visual cortex (Hubel and Wiesel 1968) much effort has been devoted to develop a
model for neuronal processing within early stages of the visual system. By applying light
spots of various sizes and shapes, these author