Neural correlates of dynamic object recognition Katja Martina Mayer Institute of Neuroscience, Newcastle University Thesis submitted for the degree Doctor of Philosophy September 2010 Table of contents Acknowledgements .................................................................................................. vii List of Figures ......................................................................................................... viii List of Tables ............................................................................................................ ix Abbreviations ............................................................................................................ xi 1. Abstract ...................................................................................................................... 1 2. Summary of previous research on recognition of multi-featured objects .................. 2 2.1. Motivation for research in object recognition .................................................... 2 2.2. The role of shape, colour, and motion in object recognition .............................. 3 2.3. Theories of object recognition ............................................................................ 7 2.3.1. Structural description models ...................................................................... 7 2.3.2. Image-based models .................................................................................... 9 2.3.3. Extensions to image-based models ............................................................. 9 2.4. Object recognition in the brain ......................................................................... 10 2.4.1. Brain areas involved in object recognition ............................................... 11 2.4.1.1. Shape sensitive areas ......................................................................... 12 2.4.1.2. Motion sensitive areas ....................................................................... 15 2.4.1.3. Colour sensitive areas ........................................................................ 17 2.5. Integrating multiple features in the brain ......................................................... 17 2.6. Cortical networks for object recognition .......................................................... 20 2.7. The role of attention in object recognition ....................................................... 23 2.7.1. BOLD modulation by attention ................................................................. 26 2.7.1.1. Attended features ............................................................................... 26 2.7.1.2. Unattended features ........................................................................... 27 2.8. Thesis overview ................................................................................................ 28 3. Interaction of colour, shape, and motion in object recognition ............................... 29 3.1. Abstract ............................................................................................................ 29 3.2. Introduction ...................................................................................................... 29 ii 3.3. Experiment 1: object learning .......................................................................... 32 3.3.1. Method ...................................................................................................... 32 3.3.1.1. Participants ........................................................................................ 32 3.3.1.2. Stimuli ................................................................................................ 32 3.3.1.3. Design ................................................................................................ 36 3.3.1.4. Procedure ........................................................................................... 36 3.3.2. Results ....................................................................................................... 39 3.3.2.1. Accuracy data .................................................................................... 40 3.3.2.2. Recognition time data ........................................................................ 41 3.3.3. Discussion ................................................................................................. 42 3.4. Experiment 2: object learning with modified objects ....................................... 42 3.4.1. Methods ..................................................................................................... 43 3.4.1.1. Stimuli ................................................................................................ 43 3.4.1.2. Computing Gabor similarity .............................................................. 45 3.4.1.3. Computing motion energy ................................................................. 45 3.4.1.4. Participants ........................................................................................ 46 3.4.1.5. Design ................................................................................................ 46 3.4.1.6. Procedure ........................................................................................... 46 3.4.2. Results ....................................................................................................... 46 3.4.2.1. Accuracy data .................................................................................... 47 3.4.2.2. Recognition time data ........................................................................ 49 3.4.3. Discussion ................................................................................................. 50 3.5. Experiment 3: Same-different comparisons ..................................................... 51 3.5.1. Method ...................................................................................................... 52 3.5.1.1. Participants ........................................................................................ 52 3.5.1.2. Stimuli ................................................................................................ 52 3.5.1.3. Design ................................................................................................ 52 3.5.1.4. Procedure ........................................................................................... 52 iii 3.5.2. Results ....................................................................................................... 53 3.5.2.1. Accuracy data .................................................................................... 54 3.5.2.2. Recognition time data ........................................................................ 55 3.5.3. Discussion ................................................................................................. 57 3.6. General discussion for Experiments 1 to 3 ....................................................... 57 3.7. Conclusion ........................................................................................................ 60 4. Experiment 4: Structural and functional networks involved in recognising dynamic objects ............................................................................................................................. 61 4.1. Abstract ............................................................................................................ 61 4.2. Introduction ...................................................................................................... 61 4.3. Methods ............................................................................................................ 65 4.3.1. Participants ................................................................................................ 65 4.3.2. Stimuli ....................................................................................................... 65 4.3.3. Design ....................................................................................................... 66 4.3.4. Procedure .................................................................................................. 66 4.3.5. Image acquisition ...................................................................................... 68 4.3.6. fMRI data preprocessing ........................................................................... 68 4.3.7. fMRI data analysis .................................................................................... 68 4.4. Results .............................................................................................................. 69 4.4.1. Behavioural results .................................................................................... 69 4.4.2. fMRI results: attending to features ............................................................ 70 4.4.3. fMRI results: attending to whole objects .................................................. 72 4.4.4. fMRI results: functional connectivity ....................................................... 76 4.5. Diffusion Tensor Imaging ................................................................................ 78 4.5.1. DTI data acquisition .................................................................................. 78 4.5.2. DTI data analyses ...................................................................................... 78 4.5.2.1. Seed regions for probabilistic fibre tracking ..................................... 79 4.5.2.2. Probabilistic fibre tracking ...............................................................