Neurocognitive networks in higher-level visual perception

The ability to accurately perceive and respond to our visual environment is critical for optimising primate behaviour. A number of related cognitive functions, such as visual learning and longer-term memory, also depend upon an accurate percept of objects and their location within the visual environment. Understanding how the healthy brain supports higher-order visual perception is, therefore, a key goal for cognitive neuroscientist. A substantial body of research involving both humans and animals highlights a role for regions within the extrastriate cortex in visual perception, with many of these regions apparently exhibiting a high degree of functional specialisation for the processing of particular categories of complex stimuli (e.g. faces versus scenes). More recently, studies have found that patients with damage to structures within the medial temporal lobe, such as the hippocampus and perirhinal cortex, can also present with impairments in higher-level perception. More specifically, damage to perirhinal cortex has been linked to impairments in perception for complex objects and faces, whereas hippocampal damage has been linked to impairments in scene perception. Multiple regions distributed across the extrastriate cortex and medial temporal lobe may make individual category-sensitive contributions to visual perception, but it remains unclear how these regions interact with one another, and to what extent their ability to interact underpins successful visual perception. These issues are addressed here via a series of novel experiments involving a combination of behavioural paradigms and magnetic resonance imaging techniques in healthy human participants. These experiments aim to: a) investigate the functional and structural connections that support the category-sensitive contributions of the perirhinal cortex and hippocampus to higher-level visual perception; b) demonstrate that inter-individual variation in the structural properties of white matter pathways providing inputs/outputs to the perirhinal cortex or hippocampus is an important factor underpinning the contributions of these regions to successful higher-level perceptions