Experience-based cortical plasticity in object category representation

TLDR: It is easier to discriminate between an apple and a pear as between two types of pears, which suggests that the neural representation of object categories is plastic, and changes as a result of experience.

Abstract: Een wetenschappelijke proeve op het gebied van de sociale wetenschappen Proefschrift ter verkrijging van de graad van doctor aan de Radboud Universiteit Nijmegen op gezag van de rector magnificus prof. mr. Contents Chapter 1 General introduction and outline 9 Chapter 2 Birds of a feather flock together: Experience-driven formation of visual object categories in human ventral temporal cortex 21 Chapter 3 Formation of category representations in superior temporal sulcus 4 3 Chapter 4 Category training induces crossmodal object representations in the adult human brain 6 1 Chapter 5 Task-and experience-dependent cortical selectivity to features informative for categorization 8 5 Chapter 6 Summary and discussion 107 Chapter 7 Nederlandse samenvatting 113 Acknowledgements 122 Biography 123 List of publications 123 Donders Graduate School for Cognitive Neuroscience Series 124 General introduction and outline 1 10 General introduction and outline R ecognizing objects and categorizing them starts already at a very young age and continues throughout adulthood. Experience continuously shapes the borders of existing categories and creates even entirely new categories. As such we can easily assign a novel instance of a known object to its category and at the same time we can discriminate between objects that look similar but are in fact different exemplars of the same category e.g. a pear and an apple. This shows that our visual system is capable of both generalization and discrimination. These are the key points of categorization. Moreover, when more skilled in recognizing fruit, for example because of working in the fruit department of a grocery store, one might even be able to distinguish a Bartlett pear from an Anjou pear (Fig 1.1). This suggests that the neural representation of object categories is plastic, and changes as a result of experience. The research in this thesis was designed to investigate experience-dependent plasticity in the representation of object categories. In the experiments in this thesis subjects were trained to differentiate between categories of computer-generated birds (Chapters 2, 3, and 4) and fish (Chapter 5). These stimuli are very difficult to distinguish without any form of training. We used behavioural measures in combination with a non-invasive brain imaging technique (functional magnetic resonance imaging, see box 1) to get insight on experience-based changes in cortical representations. Figure 1.1 It is easier to discriminate between an apple and a pear as between two types of pears. Categorization Categorization takes place at several levels of abstraction (Rosch, Mervis, Gray, Johnson, …