Chapter 58 Flashcards
What are the two types of cerebellar excitatory signals?
- Short acting excitatory signal caused by acetylcholine release from the brainstem reticular area
- Longer acting excitatory signals from the reticular excitatory area which project through the inralaminal nuclei of that thalamus and excite the cortex
What happens when the excitatory area in the pons around the level of the 5th CN is cut? What is the name of this strucutre?
- coma results
- reticular excitatory area
What is the general idea of the positive feedback loop between the excitatory area and the cortex?
the exitatory area causes excitation of the cortex, then the cortex returns an excitory signal to the bulboreticular area. This causes a positive feedback allowing for an awake state
Which brain structure acts as the relay and distribution center for activity in the cortex?
thalamus
What else does the thalamus do for the gigantocellular input as it passes to the cortex?
modulates it
What is the main purpose of the reticuloinhibitory area? What is its principle neurotransmitter?
decrease activity of the upper cortex
-serotonin
Where is the locus ceruleus?
Ponto-mesencephalon junction
What NT is released from the locus ceruleus? What is the result?
- Norepiepherine
- Generally excites the brain but does inhibit some areas
Where is the substantia nigra? What NT does it relase?
- midbrain
- dopamine
What is the action of dopamine in the brain?
-inhibitory NT on the basal nuclei
Where are the raphe nuclei and what NT do they secrete?
- midline pons
- serotonin
Where do fibers from the raphe nuclei project and what is the function of the serotonin released there?
- projecto to the diencephalon and cortex as well as the spinal cord
- in the upper levels it is inhibitory and is essential in sleep
- in the cord is supresses pain
Where are the gigantocellular neurons and what NT do they release? What is its impact?
- reticular area of the pons and mesencephalon
- Acetycholine
- excitatory function in bothe the cortex and the spinal cord (causes wakefulness)
Neurohormonal systems in the human brain (image)
What is the general role of the limbic system?
- modulate emotions and behavior
- also internal conditions like body temp, fluid osmolality, and drive to eat and drink
What are the three directions of pathways out of the hypothalamus?
- downward and outward
- upward
- into the hypothalamic infundibulum
What is the function of the hypothalamic pathway travelling downward and outward?
Travels to the brainstem (mainly to the reticular areas, mesencephalon, pons an medualla) and onward into the peripheral nerves of the ANS.
Where do the upward tracts from the hypothalamus continue on to?
-higher areas of the diencephalon and cerebrum
What is the function of the tracts that run from the hypothalamus through the infundibular stalk?
-function to contol or partially control the secretory functions of both the anterior and posterior pituitary
Where does stimulation in the hypothalamus result in an increase in blooooode pressure?
-posterior and lateral hypothalamus (increase in arterial pressure and heart rate)
Where does stimulation in the hypothalamus result in a decrease in blood pressure?
-in the preoptic area
How does the hypothalamus contribute to the regulation of body temperature?
-An increase in temperature of blood through the anterior portion of the hypothalamus results in an increase in activity of temperature sensitive neurons, while a decrease does the opposite.
In what two ways does the hypothalamus regulate body water?
- by creating the sensation of thirst
- by controlling the excretion of water into the urine (vasopressin or ADH)
Which nuclei is involved in the control of water excretion by the kidneys?
-supraoptic nuclei
How is the hypothalamus involved in the contraction of the uterus and breast?
-oxytocin secretion by neuronal cells of the paraventricular nuclei
What two nuclei of the hypothalamus are important for hunger and satiety?
- Lateral: hunger
- Ventromedial: Satiety
What would the result of stimulation of the lateral nuclei of the hypothalamus be?
- thirst
- hunger
- rage and fighting
What would be the result of stimulation of the ventromedial hypothalamic nuclei be?
-Lack of hunger (satiet) and tranquility
What happens when the thin zone of the paraventricular nucleus of the hypothalamus is stimulated?
-reactions of fear and punishment
Which portions of the hypthalamus stimulate the sex drive?
-the most anterior and most posterior portions
What is the location of the reward centers of the hypothalamus? What is the effect of stimulation of these areas?
- lateral and ventromedial nuclei
- weak stimuli= sense of reward
- strong timuli= sense of punishment
Where are the most potent punishment areas of the hypothalamus? What happens upon stimulation of these areas?
- most potent in the PAG and pariventricular areas of the hypothalamus and thalamus
- stimulation can result iin the inhibition of the reward and pleasure centers (showing how punishment can take precedence over please and reward)
What center of the brain, when stimulated in animals result in rage?
-punishment center
How is rage normally supressed or inhibited?
-inhibition by the ventromedial nuclie of the hypothalamus
If the ventromedial nuclei normally inhibit the rage response, what happens when the ventromedial nuclei are lesioned bilaterally?
-Rage
What do traquillizers do to the reward and punishment centers?
-inhibit both of them
How does the hippocampus contribute to learning? what happens if it is removed?
- causes the drive for conversion of short term memory into long term memory
- if removed, the patient can essentially no longer learn any new information of remember new things (anterograde amnesia)
What are the major functions of the amygdala?
What are the effects of stimulating the amygdala?
- behavioral and physiologic
- alteration of: arterial pressure, heart rate, GI motility, defication and micturition, pupillary dilation and constriction, piloerrection, secretion of petuitary hormones
- feelings of: rage, pleasure, reward, punishment, pain
What is Kluver-Bucy syndrome? What is the connection to older population?
- bilateral ablation of the amygdala
- lack of fear, extreme curiosity, forgetful, oral fixation, HUMPS EVERYTHING (giggity)
- Older patients afflicted with this problem tend to like to eat everything
What can lesions to the other parts of the libic cortex cause?
