Self-awareness and the medial temporal lobe in neurodegenerative diseases

Accurate self-awareness is essential for adapting one's behaviour to one's actual abilities, to avoid risky behaviour. Impaired self-awareness of deficits is common in neurodegenerative diseases. Numerous studies show an involvement of midline cortical areas in impaired self-awareness. Among the other brain regions implicated stand the medial temporal lobe (MTL) structures (i.e. hippocampus, amygdala, and temporopolar, entorhinal, perirhinal and posterior parahippocampal cortices). This review aims at evaluating the role of those structures in self-awareness in neurodegenerative diseases. To this aim, we briefly review impaired self-awareness in neurodegenerative diseases, give a neuroanatomical background on the MTL structures, and report those identified in neuroimaging studies on self-awareness. The MTL shows neuropathological, and structural or functional changes in patients who overestimate their abilities in the cognitive, socio-emotional or daily life activities domains. The structures implicated differ depending on the domain considered, suggesting a modality-specific involvement. The functional significance of the findings is discussed in view of the neuroanatomical networks of the MTL and in the context of theoretical models of self-awareness.