Inferior Parietal Lobule (Areas 39, 40)

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Inferior Parietal Lobule (Areas 39, 40)

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Location and Boundaries

Location

• Area 39 (angular gyrus)

Caudal inferior parietal lobule
• Area 40 (supramarginal gyrus)

Rostral inferior parietal lobule
• Inferior parietal lobule contains 7 distinct cytoarchitectonic regions

Boundaries

• Area 39

Caudal: Area 19 (parietooccipital sulcus)

Rostral: Area 40

Dorsal: Intraparietal sulcus

Angular gyrus is cortex surrounding caudal superior temporal sulcus (cSTS)

– cSTS has 3 branches in inferior parietal lobule: Anterior, central, and posterior branch
• Area 40

Caudal: Area 39

Rostral: Postcentral sulcus

Dorsal: Intraparietal sulcus

Ventral: Caudal aspect of circular sulcus of insula

Function

Reading

• Area 39 maps visual and auditory inputs onto semantic representations

Angular gyrus is core hub of reading network, especially cortex between central and posterior branches of cSTS
• Area 40 participates in creating representations of word sounds

Mental Arithmetic

• Area 39 participates especially when fact retrieval is required

Action Awareness

• Right area 39 processes discrepancies between intended and actual actions

Memory for Auditory Pitch

• Left area 40 direct current stimulation disrupts pitch memory

Auditory Attention

• Area 40 (lateral intraparietal sulcus) processes attention to auditory stimuli

Structural Connections

Area 39

• Connections to Broca area and Wernicke area via arcuate fasciculus
• Extensive interconnectivity with posterior temporal lobe

Area 40

• Connections to ventral premotor cortex

Functional Connections

Coactive Regions

• Area 39

Default mode network (posterior cingulate, inferior temporal, medial prefrontal)
• Area 40

Ventral attention network (inferior frontal/premotor, dorsolateral prefrontal, middle temporal, anterior cingulate, superior insula)

Associated Literature Keywords (NeuroSynth)

• Thinking, stop, awareness, no go, word, perspective, retrieved, fluency, default, recollection, game, inhibition, automatic, semantic, prosodic, story

Areas 39-, 40-Associated Disorders

Hemispatial Neglect

• Commonly seen with injury to right hemispheric ventral attention network

Dyslexia

• Functional disconnection of angular gyrus from occipital and temporal language regions hypothesized

Angular Gyrus Syndrome

• Sensory aphasia, alexia with agraphia, finger agnosia, constructional apraxia (Gerstmann syndrome) with left angular gyrus injury

Image Gallery

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INFERIOR PARIETAL LOBULE: LOCATION AND COACTIVATION

Coronal and axial slices show the relative positions of angular gyrus area 39 and supramarginal gyrus area 40 (data source: WFU PickAtlas).

Coactivation map of Brodmann areas 39 and 40 shows brain regions that reliably activate with the centroid of voxels lying within areas 39 and 40 in over 4,000 studies from the NeuroSynth database. This image is the average of left and right coactivation maps.

AREA 39: FUNCTIONAL CONNECTIVITY

Functional connectivity MR was averaged from 1,003 typically developing volunteers from the Human Connectome Project dataset. Surface renderings show correlation to a seed region in the right Brodmann area 39 as defined by the WFU PickAtlas toolbox for MATLAB. This image was displayed using BrainNet Viewer software.

Correlation to a seed region in the bilateral Brodmann area 39 is shown.

AREA 40: FUNCTIONAL CONNECTIVITY

Functional connectivity MR was averaged from 1,003 typically developing volunteers from the Human Connectome Project dataset. Surface renderings show the correlation to a seed region in the left Brodmann area 40 as defined by the WFU PickAtlas toolbox for MATLAB. This image was displayed using BrainNet Viewer software.

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Tags: Imaging Anatomy Brain and Spine

Mar 13, 2021 | Posted by admin in NUCLEAR MEDICINE | Comments Off

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