Precuneus

The precuneus is the cortex on the medial wall of the parietal lobe, tucked in front of the parieto-occipital sulcus. It is one of the most metabolically active regions of the resting brain and one of the harder to summarize — Cavanna & Trimble’s (2006) review catalogues its involvement in visuospatial imagery, episodic memory retrieval, self-processing, and consciousness. The wiki keeps meeting it under other headings; this page collects them.

Three faces of the precuneus

As a DMN hub. The precuneus (with the posterior cingulate) is a core node of the default mode network. It shows up in this wiki wherever the midline self-referential system does:

• Farb et al. (2010): untrained controls responding to a sad film recruit a midline network including the precuneus (the elaborative, self-referential mode); mindfulness training lowers that recruitment.
• Lutz et al. (2008): the “mentation” network for reading others’ mental states — precuneus/PCC, TPJ, mPFC — which expert compassion meditators drive up to emotional sounds where at rest they suppress it.

As a sensorimotor region. Margulies et al. (2009) split the precuneus by connectivity into anterior (sensorimotor), middle (cognitive-associative) and posterior (visual) thirds. Reaching, grasping, and motor-imagery activations have been reported across it.

As a body-mapped region — the new finding. Zeharia, Hofstetter et al. (2019) show the anterior-through-posterior extent of the precuneus carries a whole-body somatotopic gradient (toes-to-tongue, mirror to the SMA), confirming Penfield & Jasper’s neglected 1954 “supplementary sensory” prediction. Crucially, when they carve the precuneus by body-part preference rather than by anatomy, they recover Margulies’ motor→cognitive→visual gradient as a by-product of somatotopy: leg (anterior) voxels connect to motor cortex, SMA and the insula; hand (middle) to parietal/premotor; face (posterior) to visual cortex. The “cognitive middle” of the precuneus is, on this reading, the hand sector of a body map.

Why it matters to interoception

The precuneus is not an interoceptive region, and this page does not claim it is. Its relevance is that it is a self-processing hub that is also body-mapped — the same tension the wiki tracks in the insula, from the other side. Zeharia et al. close by proposing the precuneus homunculus and the group’s earlier insula homunculus (Zeharia et al. 2012) as a putative “node linking body and mind,” and invoke mind-body interventions that couple self-referential and body-related processing (the Farb / Lutz thread). That is a conjecture, not a result — recorded as such — but it is why an interoception wiki has a page for a parietal motor-adjacent structure: the precuneus is one of the places where the brain’s model of the self and its map of the body sit in the same cortex.