Inferior Parietal Lobule

Anatomy

• Supramarginal gyrus (BA 40) and angular gyrus (BA 39); below the IPS.
• Temporoparietal junction (TPJ): where the angular/supramarginal gyri meet the posterior superior temporal gyrus.
• Marked lateralization: left — language and number, right — attention and social cognition.
• Blood supply: inferior division of the MCA (angular artery).

Functions

• Left: reading and writing (grapheme–phoneme–meaning mapping), retrieval of arithmetic facts.
• Left supramarginal: phonological store, praxis (movement programs).
• Right: reorienting attention to unexpected stimuli (ventral attention network), spatial awareness.
• Right TPJ: representing others’ beliefs (theory of mind), self–other distinction, perspective taking.
• Multisensory integration and the sense of body ownership.

Connections and chemistry

• Broca’s and Wernicke’s areas (arcuate fasciculus)
• Right IFG (ventral attention network)
• mPFC and precuneus (mentalizing network)
• Fusiform visual word form area

Development

Developmental course through childhood and adolescence.

• Learning to read reshapes left temporoparietal circuits.
• False-belief understanding emerges around age 4; rTPJ specialization increases through childhood.

Clinical

• Dyslexia: left temporoparietal hypoactivation (phonological processing). In 20 children aged 8–12, eight weeks of language and auditory processing training improved reading; left temporoparietal and left IFG activity moved toward that of typical readers, and the left temporoparietal increase related to language gains (Temple et al., 2003). The brain can change with intervention. B
• ASD: activation differences in the rTPJ related to mentalizing.
• Dyscalculia and ADHD (ventral attention network).

Treatment

This region from the perspective of medication, psychotherapy and neuromodulation. Letter badges are evidence levels.

• Dyslexia: structured, explicit phonics-based reading instruction; intensive intervention started early is most effective. Accommodations such as extra exam time and audiobooks. A
• Dyscalculia: number sense and number line training, step-by-step teaching with concrete materials. C
• In neglect (right parietal): prism adaptation and visual scanning training (adult rehabilitation). B

Assessment

Neuropsychological tasks and measures that probe this region's function.

• Reading, spelling and phonological awareness tests
• Verbal arithmetic, finger gnosis
• Pantomime/praxis assessment
• False-belief tasks (rTPJ); line bisection and cancellation tests (neglect)

Lesions and damage

Clinical findings expected with damage or dysfunction.

• Gerstmann syndrome (left angular): agraphia, acalculia, finger agnosia, left–right confusion.
• Conduction aphasia (supramarginal/arcuate fasciculus), ideomotor apraxia (left).
• Right lesion: hemispatial neglect, anosognosia.

In the model

How this structure is defined in the 3D model, and the data source.

Supramarginal and inferior parietal (angular) cortex (CerebrA). The TPJ areas (PGi, PSL, STV, TPOJ1–3) are a separate region.

References

Full citations for the card; links go to the paper (DOI) or a PubMed search.

1. Temple E et al. Neural deficits in children with dyslexia ameliorated by behavioral remediation: evidence from functional MRI. PNAS 2003;100(5):2860–2865. Search PubMed