Physiology 3120 Lecture Notes - Lecture 27: Cingulate Cortex, Entorhinal Cortex, Road Rage
2 May 2018
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Human Physiology Lecture 27
Hypothalamus and Limbic System
November 17 2017
- Limbo (border) with brainstem
- Phylogenetically old, primitive (reptilian cortex)
o Spinal cord, then brain stem came on top to control things necessary – heart and respiratory
system
o On top of the brain stem, the limbic system to control more advanced states + behaviours
o Mammals added the cerebral hemisphere with the new cortex = neocortex
▪ Parts of the neocortex influence the old limbic cortex & can override it
o Inherited by mammals
- Structures in limbic system: Cingulate cortex, Hypothalamus, Amygdala, Hippocampus
o NO MC ABOUT WHICH STRUCTURES ARE IN LIMBIC SYSTEM
- On the top of the brain stem there is a phylogenetically old cortex = limbic system
- Limbic system is ring of phylogenetically primitive cortex around the brain stem & its
interconnecting structures
- Limbo = border
- Limbic system is the rostral border of the brain stem
o Concerned with emotion, certain motivational states + behaviours (Homeostatic and
instinctual drives) and memory
- Limbic system is primitive (reptilian) and is essential
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Limbic System Function
Emotion, Motivational States
Behaviours
Cold/Hot
Clothes, Move (shivering)
Hunger
Feeding
Thirst
Drinking
Rage / fear
Attack / Defense
- Rabies virus affects limbic cortex: changes in emotional
state such as bouts terror, rage
- Daily life limbic rage behaviour: road rage, slap face
(fights)
Note: can override the neocortex + limbic cortex
Sexual urge
Mating
Pain /Nociceptive afferents
Avoidance
- Somatosensory cortex (Location, Intensity, Timing)
- Cingulate cortex: Emotional Component (lesion: feel pain
but not bothered by it) psychological aspect of pain
- Note: small # of people that have had lesions in the
cingulate cortex area can feel pain but are not bothered
by it b/c the cingulate cortex is associated with the
emotional component of brain
- Can not just get ride of the cingulate cortex b/c damage
other functions of the limbic system
- Goes up the spinothalamic system to the post central gyrus,
BUT in mammals, there is the dorsal medial lemiscal
pathway that also goes to the somatosensory cortex (90%
of neuronal connections in the somatosensory cortex)
Hypothalamus
- Receives input from the limbic cortex
- < 1% volume of brain
- Remarkable number of functions
- Lesion can be catastrophic
o Hypothalamus controls vegetative activities – if any are
disordered, there are many problems in the individual’s life
- In charge of the autonomic nervous system
- Location: underneath the thalamus
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- Note: limbic system includes the old limbic cortex
- Hypothalamus part of the limbic system
- One of the important sensory inputs to the hypothalamus is the retina: needed for saccadian rhythms
- There is an array of sensory information from entire body and environment that goes to the
hypothalamus
- Hypothalamus has axons that project to the posterior pituitary – release 2 hormones: oxytocin + ADH
- Portal system = highly specialized system of blood vessel releasing and releases inhibiting hormones
sent from the hypothalamus down the vascular portal system via hypophysial portal veins to anterior
pituitary
o Used for release of variety of different hormones
- Neuron connections form the hypothalamus to to the medulla down to the spinal cord
- Feature of hypothalamus: there are neurons that have receptors on them – receptors for:
o Osmolality
o Glucose
o Temperature
o Sodium
o Leptin
o Detect the concentrations in circulating blood of the different variables
- Leptin (hormone)
o Made in fat storage cells
o Signals size fat stores
▪ Has feedback as a hormone, into the circulating blood, back to the hypothalamus to
reduce food intake
o Reduces food intake
o Obese humans may be insensitive to leptin or have a mutation in the leptin gene or leptin
receptor gene
find more resources at oneclass.com
find more resources at oneclass.com
