chapter 58: behavioral and motivational mechanisms of the brain—the limbic system and the...
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Unit Eleven: The Nervous System: C. Motor and
Integrative Neurophysiology
Chapter 58: Behavioral and MotivationalMechanisms of the Brain—The Limbic
System and the Hypothalamus
Guyton and Hall, Textbook of Medical Physiology, 12 edition
Activating—Driving Systems of the Brain
• Control of Cerebral Activity by Continuous Excitatory Signals from the Brain Stem
a. Reticular excitatory area of the brain stem-sends signalsupward and downward
b. Downward-to spinal cord reflexes and to maintain tonein the antigravity muscles
c. Upward through the thalamus (two signals)
1. Rapid transmission to excite the cerebrum2. Build up progressively for seconds to minutes
Activating—Driving Systems of the Brain
Fig. 58.1 Excitatory-activating system of the brain
Activating—Driving Systems of the Brain
• Excitation by Peripheral Sensory Signals
• Increased Activity of the Excitatory Area Caused by Feedback Signals
ReturningFrom the Cerebral Cortex
• Thalamus is a Distribution Center That Controls
Activity in Specific Regions of the Cortex
• A Reticular Inhibitory Area is Located in the
Lower Brain Stem
Activating—Driving Systems of the Brain
• Neurohormonal Control of Brain Activity-Three
Systems Studied in the Rat
a. Norepinephrine system-excitatory and can go toevery area of the brain
b. Dopamine system-can be both excitatory and inhibitory; goes to specific brain regions
c. Serotonin system-inhibitory; goes to specific brain regions
Activating—Driving Systems of the Brain
• Neurohormonal Systems in the Human Brain
a. Same three as in the rat plus
b. The acetylcholine system
Activating—Driving Systems of the Brain
• Neurohormonal Systems in the Human Brain
Fig. 58.2 Fig. 58.3
Activating—Driving Systems of the Brain
• Other Neurotransmitter and Neurohormonal
Substances Secreted in the BrainNeurotransmitter Or Neurohormone
Enkephalin ACTH
GABA MSH
Glutamate Neuropeptide Y
Vasopressin Epinephrine
Histamine Angiotensin II
Endorphins Neurotensin
Limbic System
• Functional Anatomy of the Limbic System
Fig. 58.5 Limbic system showing the key position of the hypothalamus
Limbic System
• Functional Anatomy of the Limbic System
Fig. 58.4 Anatomy of the limbic system
Limbic System
• Hypothalamus, a Major Control Center for the
Limbic System
a. Has two-way communicating pathways with all levels of the limbic system; sends output signals inthree directions:
1. To the brain stem (mesencephalon, medulla, and pons) and then to the ANS
2. To higher areas of the diencephalon and cerebrum
3. To the infundibulum to control secretions of the anterior and posterior pituitary
Limbic System
• Hypothalamus, a Major Control Center for the
Limbic System
b. Vegetative and endocrine control functions of the hypothalamus
c. Areas that cause specific activities are not as accurately localized as suggested in the following figures
Limbic System
Fig. 58.6 Control centers of the hypothalamus
Limbic System
Fig. 58.7 Coronal view of the hypothalamus
Limbic System
• Behavioral Functions of the Hypothalamusand Associated Limbic Structures
a. Effects caused by stimulation of the hypothalamus
1. Lateral-thirst and eating; increases the generallevel of activity (possibly rage and fighting)
2. Ventromedial nucleus-satiety, decreasedeating, and tranquility
3. Periventricular nuclei-fear and punishmentreactions
4. Anterior and posterior hypothalamus-sex drive
Limbic System
• Behavioral Functions of the Hypothalamusand Associated Limbic Structures
b. Effects caused by hypothalamic lesions
1. Bilateral lesions-decrease eating and drinking to zero; extreme passivity
2. Ventromedial areas-excessive eating anddrinking; hyperactivity; continuous rageand savagery
Limbic System
• Reward and Punishment Function of the LimbicSystem
a. Reward centers
b. Punishment centers
c. Rage-association with punishment centers
d. Placidity and tameness
Limbic System
• Importance of Reward and Punishment on Behavior
a. Effect of tranquilizers on reward and punishment
b. Importance in learning and memory
Specific Functions of Other Parts of the Limbic System
• Functions of the Hippocampus
a. Role in learning
b. Theoretical function
• Functions of the Amygdala
• Functions of the Limbic Cortex
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