T21. BEHAVIORAL AND EMOTIONAL MECHANISM OF THE BRAIN Flashcards
(29 cards)
What is the limbic system primarily involved in?
Control of emotions and motivations, especially those related to survival (fear, anger, sexual behavior), and it contains centers for gratification and aversion.
Where is the limbic system located?
Buried below the cortex, forming a ring around the brain stem.
Why is it hard to control emotions according to limbic system anatomy?
Because the limbic system is phylogenetically older than the cortex and has few synaptic connections with it.
Which brain structures are part of the limbic system?
Hypothalamus, thalamus, cingulate gyrus, amygdala, and hippocampus.
How is the hippocampus connected within the limbic system?
Connected to the hypothalamus via the fornix; sends neurons to the thalamus, which sends neurons to the cingulate gyrus, completing the Papez circuit.
What is the most important structure in the control pathways of the limbic system?
The hypothalamus.
What are the three directions of hypothalamic output signals?
- To brainstem and peripheral autonomic nerves;
- To thalamus and limbic cortex;
- To hypothalamic infundibulum for pituitary control.
What are some vegetative and endocrine functions regulated by the hypothalamus?
Cardiovascular function, body temperature, water balance, uterine contractility, milk ejection, GI and feeding, endocrine secretion.
Which hypothalamic area regulates cardiovascular functions?
Various areas throughout the hypothalamus can regulate arterial pressure and heart rate.
Which hypothalamic region regulates body temperature?
The anterior portion of the hypothalamus.
What are some endocrine and reproductive functions regulated by the hypothalamus?
Water regulation, uterine contractions, milk ejection, and anterior pituitary hormone secretion.
What effect does electrical stimulation of certain limbic areas have?
Pleasure or satisfaction in some areas; fear, pain, and punishment in others.
How do stimulation or lesions in the hypothalamus affect behavior?
They can cause aggression, satiety, fear, sexual drive, or opposite effects depending on the area stimulated or lesioned.
What behavioral effect results from stimulating the lateral hypothalamus?
Aggression.
What behavioral effect results from stimulating the ventromedial hypothalamus?
Satiety, decreased eating, and tranquility.
What behavioral effect results from stimulating the periventricular nucleus of the hypothalamus?
Fear and punishment reactions.
What is the effect of stimulating various hypothalamic areas related to reproduction?
Sexual drive.
What are the effects of bilateral lesions in the lateral hypothalamus?
Decrease in drinking and eating (leading to possible lethal starvation) and extreme passivity.
What are the effects of bilateral lesions in the ventromedial hypothalamus?
Excessive drinking and eating and hyperactivity.
What behavioral patterns can be caused by hippocampus stimulation?
Pleasure, passivity, or excessive sex drive.
What is the result of bilateral removal of the hippocampus?
Anger, violence, escape behavior, punishment, anxiety, and fear.
What behavioral responses can be caused by stimulation of the amygdala?
Anger, violence, escape behavior, punishment, anxiety, and fear.
What happens when the amygdala is damaged?
Hyperorality, hypersexuality, and disinhibited behavior.
Which drugs act on the amygdala and how?
Benzodiazepines inhibit GABA receptors in the amygdala, acting as minor tranquilizers.
