Papez回路

機能 / Function

情動と記憶（特にエピソード記憶の形成）に関わる辺縁系の閉回路。海馬体→脳弓→乳頭体→乳頭視床路→視床前核→視床帯状放線→帯状回→帯状束→海馬傍回（嗅内皮質）→海馬体へと戻る。Papez（1937）が情動の神経回路として提唱し、現在は記憶の形成・固定化に重要とされる。

A closed limbic loop for emotion and (especially episodic) memory formation: hippocampal formation → fornix → mammillary body → mammillothalamic tract → anterior thalamic nucleus → thalamocingulate radiation → cingulate gyrus → cingulum → parahippocampal/entorhinal cortex → back to the hippocampus. Proposed by Papez (1937) for emotion; now regarded as important for memory encoding and consolidation.

主要構造 / Key structures

• 海馬体Hippocampal formation
• 脳弓Fornix
• 乳頭体Mammillary body
• 視床前核Anterior thalamic nucleus
• 帯状回Cingulate gyrus
• 海馬傍回（嗅内皮質）Parahippocampal (entorhinal) cortex

回路破綻による症状 / Symptoms of disruption

回路の障害で前向性健忘を主とする記憶障害（エピソード記憶の形成障害）。乳頭体・乳頭体視床路・内側視床の障害では前向性・逆向性健忘に作話を伴うことがあり、急性期には眼球運動障害・失調・意識障害を呈しうる。海馬・嗅内皮質の障害は近時記憶障害（エピソード記憶障害）を、脳弓の障害も健忘を来す。

Disruption causes memory impairment, predominantly anterograde amnesia (impaired episodic memory formation). Damage to the mammillary bodies, mammillothalamic tract and medial thalamus can produce antero- and retrograde amnesia with confabulation, and acutely ophthalmoplegia, ataxia and confusion. Hippocampal/entorhinal damage causes recent (episodic) memory impairment, and fornix damage likewise causes amnesia.

関連する疾患 / Associated diseases

乳頭体・乳頭体視床路・前視床核(背内側核も関与)→ Wernicke-Korsakoff 症候群(チアミン欠乏)。海馬・嗅内野 → Alzheimer 病。内側側頭・辺縁系 → 自己免疫性/傍腫瘍性辺縁系脳炎、単純ヘルペス脳炎。

Mammillary bodies / mammillothalamic tract / anterior thalamic nucleus (dorsomedial nucleus also involved) → Wernicke-Korsakoff syndrome (thiamine deficiency). Hippocampus/entorhinal cortex → Alzheimer's disease. Medial temporal/limbic structures → autoimmune/paraneoplastic limbic encephalitis, herpes simplex encephalitis.

出典 / References

• Papez JW. Arch Neurol Psychiatry 1937
• Catani M, et al. Cortex 2013 (limbic connectivity)