No abstract

No abstract

Mental imagery and visual perception rely on the same content‐dependent brain areas in the high‐level visual cortex (HVC). However, little is known about dynamic mechanisms in these areas during imagery and perception. Here we disentangled local and inter‐regional dynamic mechanisms underlying imagery and perception in the HVC and the hippocampus (HC), a key region for memory retrieval during imagery. Nineteen healthy participants watched or imagined a familiar scene or face during fMRI acquisition. The neural code for familiar landmarks and faces was distributed across the HVC and the HC, although with a different representational structure, and generalized across imagery and perception. However, different regional adaptation effects and inter‐regional functional couplings were detected for faces and landmarks during imagery and perception. The left PPA showed opposite adaptation effects, with activity suppression following repeated observation of landmarks, but enhancement following repeated imagery of landmarks. Also, functional coupling between content‐dependent brain areas of the HVC and HC changed as a function of task and content. These findings provide important information about the dynamic networks underlying imagery and perception in the HVC and shed some light upon the thin line between imagery and perception which has characterized the neuropsychological debates on mental imagery.

No abstract

No abstract

No abstract

No abstract

We aimed to address the long-standing issue of the nature of the relationships that link a cue word to words associated with it. In keeping with a recently proposed neuropsychological model of semantic memory (Zannino et al., 2015), we provide support for the hypothesis that associative links are semantic in nature and not lexical. In support of this hypothesis, we demonstrate a relationship in healthy subjects between the probability of producing word X in response to cue word Y in a free association task and the probability of using word X to describe the meaning of word Y. Furthermore, we provide evidence that associative measures are altered in people suffering from Alzheimer's disease (AD) and predict their level of performance in a picture-naming task. We provide a parsimonious account of the experimental data gathered form these different sources of evidence according to the hypothesis that the links between a cue word and its associates can be viewed as binding a concept (the cue) to pieces of information regarding its meaning (the associates).