Visual and spatial working memory: from boxes to networks.

It is shown that visuo-spatial working memory is better characterized as processes operating on sensory information (visual appearance) and on spatial location (environmental coordinates) in a distributed network than as unitary slave system. Results from passive (short-term) and active memory tasks (imagery) disclose the properties (capacity, content) and the components of this network. The prefrontal cortex is a control structure (dorsal prefers active, ventral passive tasks) and it contributes to spatial memory by a prospective spatial code (eye movements). Visual appearance (including dynamic aspects) is represented as features and object files (bound features) within content-specific areas in the ventral occipital cortex. Spatial coordinates are represented in the parietal cortex (modality-unspecific), when used in spatio-temporal tasks (Corsi) they are closely related to attention. Imagery of objects activates occipito-temporal structures, spatial transformations and mental rotation the parietal cortex (specifically the intraparietal sulcus). Perception, working memory, and imagery use the same neural network. Differences between the tasks are explained by different demands and states of the neural network, and differences in the configuration of the anterior-posterior neural circuits.