Physiology 3120 Lecture Notes - Lecture 24: Cingulate Cortex, Entorhinal Cortex, Leptin Receptor
15 May 2018
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Lecture 24 – Hypothalamus and Limbic System
- Limbo (border) with brainstem
- Located at the top of the brain stem
- Phylogenetically old, primitive cortex (reptilian cortex) inherited by mammals
o Through phylogenetic development in animals, started first with spinal cord and
then brainstem came on top of it with areas to control things necessary for life
(heart and respiratory system)
o On top of the brain stem is the old cortex to control more advanced states and
behaviors = limbic cortex
o When mammals came along, they kept the limbic system and brainstem and added
cerebral hemispheres and a new cortex called the neo cortex
o New cortex still influences the old limbic cortex and can override it
o There are expanded perceptual areas in the brain now (visual, auditory, motor, etc)
- Structures in the limbic system:
o Cingulate cortex
o Hypothalamus
o Amygdala
o Hippocampus
Limbic system function
- Emotion
- Motivational states
- Rabies virus affects limbic cortex
o Show botus terror, rage
- Daily life: road rage, slap face
o Attributed to the limbic cortex
o If sitting down and someone slapped you, limbic cortex would tell the body to slap
them back if they are small
o Limbic cortex decides if its better to be aggressive or defensive
- Neocortex can override and limbic cortex
find more resources at oneclass.com
find more resources at oneclass.com
o E.g. if there is a murder in the house, the police surround the house and wait and
after 24h, limbic activity has gone down and they will walk out. By rushing the
murderer, they are still in limbic mode and will cause trouble
- Mammals have the dorsal column which also goes to the postcentral gyrus and takes up
about 90% of neuronal connections in the cortex
- 10% of all projections to somatosensory cortex come from spinothalamic system (i.e pain)
- Somatosensory cortex: nociceptor afferent information is recognized as pain
o Somatosensory cortex gives the location of the pain, intensity of it and timing (how
long it lasts)
o Pain is sent to various parts of the pain
- Cingulate cortex also receives nociceptor afferent information (pain) – part of the limbic
cortex
- Cingulate cortex: signals emotional component of pain
o Psychological bad aspect of pain
o Chronic pain has a negative impact on psychological state
o LESION in cingulate cortex pain area: feel pain, but not bothered by it
- Making lesions in the cingulate cortex to reduce pain during surgery?
o There are other things happening within the limbic system in this region
o Risks of doing damage to other parts of the limbic system
o Worse off in terms of after having lesions in terms of day to day interactions,
behavior and memory
o Surgery is not usually performed in the cingulate cortex
Hypothalamus
- Receives input from the limbic cortex
- Governs the autonomic nervous system
- Less than 1% volume of brain
- Remarkable number of functions
- Lesion: catastrophic
- Controls vegetative activities
find more resources at oneclass.com
find more resources at oneclass.com
- Could take out 1% of neocortex – wouldn’t even know it was missing but if made the same
lesion in the hypothalamus, it would be catastrophic
- Hypothalamus is under the thalamus
Leptin (hormone)
- Made in fat storage cells
- Signals size fat stores
- Has a feedback as a hormone into the circulating blood to the hypothalamus
- Effect: reduces food intake
- Obese may be insensitive to leptin
o Or mutation gene for leptin or gene leptin receptor in the hypothalamus
- Limbic system: old limbic cortex
- Hypothalamus is part of the limbic system – could say that about areas of medulla and
spinal cord
- Sensory input to hypothalamus:
o Retina: needed for circadian rhythms
o Huge array of sensory information from entire body and environment that goes to
the hypothalamus as well
- Outputs:
o Has axons that projects to posterior pituitary where they release two hormones:
oxytocin and ADH
- Anterior pituitary:
o Portal system: highly specialized system of blood vessels that gets releasing and
releasing inhibiting hormones sent from the hypothalamus through the vascular
portal system by the hypophysial portal veins to anterior pit.
o Used for release for many hormones
- Neuroconnections from the hypothalamus to the medulla and down to the spinal cord
- There are neurons which have receptors on them for osmolality, glucose, temperature,
sodium and leptin
o Detect concentration in circulating blood of different variables
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Located at the top of the brain stem. Structures in the limbic system: cingulate cortex, hypothalamus, amygdala, hippocampus. Rabies virus affects limbic cortex: show botus terror, rage. Daily life: road rage, slap face: attributed to the limbic cortex. If sitting down and someone slapped you, limbic cortex would tell the body to slap them back if they are small: limbic cortex decides if its better to be aggressive or defensive. Neocortex can override and limbic cortex: e. g. if there is a murder in the house, the police surround the house and wait and after 24h, limbic activity has gone down and they will walk out. By rushing the murderer, they are still in limbic mode and will cause trouble. Mammals have the dorsal column which also goes to the postcentral gyrus and takes up about 90% of neuronal connections in the cortex. 10% of all projections to somatosensory cortex come from spinothalamic system (i. e pain)
