Limbic System Dr. Skantha Kandiah MBA, MSc (NUI), MB BCh BAO (NUI), LRCP & SI Senior Lecturer in Anatomy and Lecturer in Healthcare Management RCSI

Limbic System Cingulate gyrus Hippocampus Fornix Mamillary bodies Septal nuclei Amygdala

Cingulate gyrus

Hippocampus

Fornix

Mamillary bodies

Septal nuclei

Amygdala

FORNIX CONNECTS MAMMILLARY BODIES TO HIPPOCAMPUS Efferent fibres from hippocampus form fimbria

CONNECTS MAMMILLARY BODIES TO HIPPOCAMPUS

Efferent fibres from hippocampus form fimbria

NUCLEUS ACCUMBENS Stimulation – sense of well-being Connection to basal nuclei – motor expression of emotion? SEPTAL AREA – stimulation – sensation like orgasm Destruction of septal area -- rage

NUCLEUS ACCUMBENS

Stimulation – sense of well-being

Connection to basal nuclei –

motor expression of emotion?

SEPTAL AREA – stimulation – sensation like orgasm

Destruction of septal area -- rage

AMYGDALA At tip of tail of caudate nucleus and anterior horn of lateral ventricle Fear – important for survival ? Overactivity – rage ? Role in phobias Bilateral ablation – timidity, hypersexuality.

At tip of tail of caudate nucleus and anterior horn of lateral ventricle

Fear – important for survival

? Overactivity – rage

? Role in phobias

Bilateral ablation – timidity, hypersexuality.

HIPPOCAMPUS IMPORTANT FOR MEMORY 3 layers of cells (allocortex) Alzheimer’s disease General cortical degeneration Hippocampal degeneration (bilateral) – cannot form new memories Frontal degeneration – inappropriate behaviour, later -= attention and motivation deficit

IMPORTANT FOR MEMORY

3 layers of cells (allocortex)

Alzheimer’s disease

General cortical degeneration

Hippocampal degeneration (bilateral) – cannot form new memories

Frontal degeneration – inappropriate behaviour, later -= attention and motivation deficit