Neurosurgery notes/Anatomy/White matter tracts/Association fibres/Amygdalofugal pathway/Ventral amygdalofugal pathway

Ventral amygdalofugal pathway

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Amygdalofugal pathway

General

  • Aka:
    • Inferior thalamic peduncle
    • Ansa peduncularis
  • Part of the subthalamus
  • Shaped like the letter "S"
  • Located at junction between temporal pole and frontal lobe
  • A limbic tract

Segments

  • Temporal segment
  • Frontal segment

Composed of

Left (A) and right (B) view. - AS: amygdaloseptal fibres - AT: Amygdalothalamic fibres - AH :Amydalohypothalamic fibres
Left (A) and right (B) view. - AS: amygdaloseptal fibres - AT: Amygdalothalamic fibres - AH :Amydalohypothalamic fibres
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Amygdaloseptal fibres
  • Aka: Horizontal limb of the Diagonal band of broca (DBB)
  • Connection:
    • Amygdala ↔ septal area/nucleus
      • Meets the indusium griseum along the medial surface of the nucleus accumbens to form the paraterminal gyrus, which is part of the septal region at the subcallosal area
      • Medially, this bundle may continue with the precommissural fornix at the septal region and laterally reach the amygdala and anterior temporal cortex.
  • Location:
    • Dorsal to the amygdalohypothalamic pathway within the ansa peduncularis
  • Fx:
    • The amygdala may influence the septal nucleus directly through amygdaloseptal pathway and affect the hypothalamus, midbrain and hippocampus indirectly by the septal nucleus.
        • notion image
Amygdalohypothalamic fibres
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  • Connection:
    • Amygdala ↔ hypothalamus
  • Runs ventrally to the amygdaloseptal pathway and enters the anterior hypothalamus
  • Fx
    • Amygdala to control the hypothalamus and influence the endocrine function and automatic nervous system indirectly.
Amygdalothalamic fibres
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  • Aka: medial forebrain bundle
    • Inferior thalamic peduncle
    • Extracapsular thalamic peduncle
  • Connects the anterior temporal cortex + amygdala ↔ medial thalamus ↔ prefrontal and orbitofrontal cortex.
  • Relation:
    • Posterior to the amygdaloseptal pathway
    • Dorsal to the hypothalamuss
  • Fx

Connections

  • Amygdala → Nucleus accumbens/ Subgenual part of cingulate gyrus/Gyrus rectus

Relations

  • Superior:
    • Anterior perforating substance
  • Inferior:
    • Optic tract
  • Medially
    • Columns of Fx
    • Rostrum of corpus callosum
  • Laterally
    • Caudate nucleus
    • Temporal radiations of the uncinate fasciculus
  • Anterior commissure
    • Have a parallel direction with the anterior commissure and optic tract
    • The anterior commissure, which crosses the AP being anterior to the temporal segment and posterior to the frontal segment of AP.
        • Fx, fornix; AC, anterior commissure; ACF, anterior column of fornix; CN, caudate nucleus; AP, ansa peduncularis; OT, optic tract; A, amygdala; H, hippocampus; DCg, dorsal cingulum; ST, stria terminalis; T, thalamus; FH, fimbria hippocampi; DG, dentate gyrus; PCg, parahippocampal cingulum; CC, corpus callosum; OR, optic radiations; AL, anterior limb of internal capsule
        Fx, fornix; AC, anterior commissure; ACF, anterior column of fornix; CN, caudate nucleus; AP, ansa peduncularis; OT, optic tract; A, amygdala; H, hippocampus; DCg, dorsal cingulum; ST, stria terminalis; T, thalamus; FH, fimbria hippocampi; DG, dentate gyrus; PCg, parahippocampal cingulum; CC, corpus callosum; OR, optic radiations; AL, anterior limb of internal capsule

Function

  • Multimodal sensory integration
  • Behavioural inhibition

Deficits

  • Impaired modulation of social behaviour
  • Learning and recall deficits