BA 1-3 - primary somatosensory

In the volumetric brain

The Territory

Structure. Brodmann areas 1–3: the postcentral gyrus' granular koniocortex — area 3b receives the thalamic VP core input, areas 3a/1/2 integrate muscle-spindle and cutaneous maps; a strict somatotopy runs medial (foot) to lateral (face).

Function. Primary body-sense map: touch, vibration, position — the first cortical somatosensory stage whose local damage yields contralateral astereognosis and tactile extinction with intact primary detection thresholds.

The Levers — graded instruments & the levers to come

Behaviour · Action · Thought — the tagged profile

The Network — what fires with this region

Papers on disk — 177 full texts

The Evidence — Neurosynth studies (849)

The Evidence — NeuroQuery studies (765)

The Exploration Guide

*Parietal lobe · Mai atlas of record · 849 studies · 118 papers on disk*

This is the body's first cortical map — the postcentral koniocortex where touch, vibration and limb position arrive in strict somatotopic order, foot medial to face lateral. The right-hemisphere patch reads the left body.

The Territory

Brodmann areas 1–3: the postcentral gyrus' granular koniocortex — area 3b receives the thalamic VP core input, areas 3a/1/2 integrate muscle-spindle and cutaneous maps; a strict somatotopy runs medial (foot) to lateral (face).

*— {'source': 'Gazzaniga, Ivry & Mangun', 'work': 'Cognitive Neuroscience: The Biology of the Mind, 4th ed., W. W. Norton', 'kind': 'textbook', 'locator': 'ch. 5, Sensation and Perception'}*

What It Does

Primary body-sense map: touch, vibration, position — the first cortical somatosensory stage whose local damage yields contralateral astereognosis and tactile extinction with intact primary detection thresholds.

The functional record is precise: area 3b takes the thalamic VP core input, areas 3a/1/2 integrate spindle and cutaneous maps; local damage yields contralateral astereognosis and tactile extinction with primary detection thresholds intact — the patient feels the cotton but cannot name the key in their pocket. The decoded profile is hand, finger, movement, pain: the working body. The graded matrix carries the somatosensory family complete — two-point discrimination as assessor, texture-roughness as stimulator, tactile adaptation as inhibitor.

*— {'source': 'Gazzaniga, Ivry & Mangun', 'work': 'Cognitive Neuroscience: The Biology of the Mind, 4th ed., W. W. Norton', 'kind': 'textbook', 'locator': 'ch. 5, Sensation and Perception'}*

The Network

The map is a sensorimotor loop: primary motor (1,030 shared studies), postcentral sulcus and gyrus, SMA, premotor — touch and action firing together, as they do whenever you grip anything.

Co-activation partners of record: BA 4 - primary motor:1030, Postcentral sulcus:571, Postcentral gyrus:563, Supplementary motor area:473, BA 6 - premotor/SMA:412, Cingulate gyrus, anterior:398, Thalamus:386, Precentral gyrus:370.

When It Fails

Astereognosis and tactile extinction from local damage; the thalamic-attention study in its evidence marks the gating role. With 849 studies the body map is thoroughly recorded.

The Evidence

• A specific role for the thalamus in mediating the interaction of attention (1998)
• Activation of Heschl's gyrus during auditory hallucinations. (1999) — 10.1016/S0896-6273(00)80715-1
• Human cortical regions involved in extracting depth from motion. (1999) — 10.1016/S0896-6273(00)81040-5
• Fast reaction to different sensory modalities activates common fields in th (2000)
• Understanding dissociations in dyscalculia: a brain imaging study of the im (2000) — 10.1093/brain/123.11.2240
• Physiological dysfunction of the dorsolateral prefrontal cortex in schizoph (2000) — 10.1093/cercor/10.11.1078

849 studies total touch this region in the Neurosynth corpus of record; the full literature lives beside this dossier.

The Levers

• two-point-discrimination — assessor · standard-scientific
• texture-roughness — stimulator · standard-scientific
• tactile-adaptation — inhibitor · standard-scientific
• tactile-detection — stimulator · standard-scientific
• tactile-detection — assessor · standard-scientific

Candidate levers (Neurosynth-decoded terms — motor(action-motor), hand(action-motor), movement(action-motor), movements(action-motor), m1(anatomy-reference), somatosensory(method-other), sensorimotor(method-other), finger(action-motor) …) are the foundation for the thousands of instruments to come; they are ungraded by law.

Explore Further

BA 4 - primary motor:1030, Postcentral sulcus:571, Postcentral gyrus:563, Supplementary motor area:473 — each name is a dossier stop in this explorer.

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