The fading self in space-disruption of default spatial representation across neurological disorders.

Neurological disorders stem from an intermingled change to self-in-space. While many of these disorders present as spatial deficits-contralateral neglect syndrome, for example-they manifest from the same etiology: disruption to the brain's "default spatial representation" (DSR). DSR is a basic internally generated representation of space that delineates where the self is located in space-without attentional focus from an external drive. We review how pathologic disintegration of DSR is associated with anomalous activation and connectivity within distinct large-scale brain networks (e.g., the default mode network and a comprehensive attention-networked system), leading to a heterogeneous presentation of clinically assessed outcomes. The outcomes include psychogenic paralysis of limbs, left-side neglect, rectified sense of other locations, disorders of consciousness, symptoms related to autism spectrum disorder, Alzheimer's disease, schizophrenia, and depersonalization/derealization disorder. By consolidating evidence from neuroimaging, lesion-symptom mapping, and computational assessment, we aim to reconceptualize these disorders not as separate and independent maladies, but as manifestations of a deeper, shared etiology, supporting a network-based assessment strategy for diagnosis and treatment that seeks to restore self-in-space.