Lecture 14

Limbic System

• Limbic system encircles the upper portion of the brainstem and includes:
  
  • Olfactory Bulbs
    
  • Amygdaloid bodies
    
  • Cingulate Gyrus (in the medial side of the hemisphere at the top)
    
  • Parahippocampal Gyrus
    
  • Hippocampus (the internal gyrus that goes into the inferior horn of the lateral ventricle)
    
  • Fornix
    
  • Mammillary Bodies of the hypothalamus
    
  • Thalamic and Hypothalamic nuclei
    
• Much of the brain is 6 layers deep, but parts of it are 3 layers deep.
  
• 3 layer parts are the Allocortex.
  
• 6 layer parts are the Neocortex.
  
• Transition areas between the 3 and 6 layer portions that are called the Juxtallocortex, it has 4 to 5 layers.
  
• Papez Circuit proposed by Papez (1930's) – it started at the Hippocampus (the Hipppocampus is part of the Allocortex).  The only efferent outlet of the Hippocampus is the Fornix, and it conducts in one direction and sends everything to the mammillary bodies. 
  
  • Circuit starts at the Hippocampus (via the Fornix)  Mammillary bodies of Hypothalamus  Anterior nuclei of Thalamus  Cigulate gyrus  Parahippocampal gyrus  Hippocampus.
    
  • He believed that the hippocampus was where emotions were organized.
    
  • Today the hippocampus is studied for memory not for limbic system function.
    
• The Limbic System is part of the brain that is responsible for:
  
  • Seeking and capturing prey
    
  • Courtship
    
  • Copulation
    
  • Maternal and Paternal behavior
    
  • Emotional Responses
    
  • Aggressive as well as communal behavior
    
  • Fight or flight
    
  • Memory formation
    
• Copulation:
  
  • In men there are many social, psychological, or neo-cortical functions that are going into sexual behavior.
    
    • Typically when we discuss sexual behavior, we talk about lower mammalian species that don't have as many social and psychosocial input and only talk about the basic instincts that are being formed by the Limbic system
      
  • Gonadal hormones stimulate sexual behavior in both the male and the female.
    
    • Testosterone in male, Estrogens in female.
      
  • In Males and Female – Gonadal hormone levels are detected/monitored by the hypothalamus.
    
  • In virtually all mammalian species the male's sexual activity interest is continuous.
    
  • The female in mammalian species, sexual activity is controlled the Estrus cycle. The Estrus Cycle is controlled by relative levels of estrogen and progesterone (relative level is used b/c to compare relativity to own level – ex. when they are relatively high or low)
    
    • When Estrogen levels increase – female in heat – we call this Estrus
      
      • The female is receptive to sexual intercourse
        
    • When Progesterone is high – female is out of heat – we call this Diestrus.
      
  • Certain mammals stop cycling their Estrus Cycle because they do not want to have their babies in the winter time.
    
    • Deer who would give birth in January would have high death rates of fawns.
      
    • The Doe will go through an Anestrus period – they do not cycle at all.
      
      • We think that Anestrus is brought on by day length, and when the day get short Anestrus will set in
        
  • The female will copulate only during Estrus, which is just prior to ovulation
    
  • We don't have an Estrus cycle in human females, but we do have signs of it
    
  • Human females – exhibit more skin in public in the few days prior to their ovulation.
    
    • Human females exhibit more sexual activity just prior to ovulation, and this is when their estrogen level is the highest.
      
    • Vaginal secretions of the female include Pheromones, which are fatty acid chemical signalers, that can actually result in various unlearned behaviors (such as having sex or suckling the breast).
      
      • Males that sense the pheromones of the vagina will become more sexually aggressive.
        
      • Female secrets pheromones form her nipples and the baby can smell and it knows to suckle.
        
• Fear and Rage – are closely related emotions (ex. If you chase a dog it will run from you, but if you are in an alley the fear of the dog will quickly turn to rage)
  
  • Fear and rage are centered in both Hypothalamic nuclei and the Amygdaloid body.
    
    • If the Amygdaloid body is destroyed you will have an animal that is fearless and rageless.
      
    • Some of the Hypothalamic nuclei are calming centers – this is b/c if they are destroyed you can cause rage in the animal.
      
    • We can create rage by stimulating the Lateral Hypothalamus.
      

 
 

• Higher learning and memory:
  
  • Memory can be divided in 2 types – Non-declarative Memory and Declarative Memory
    
  • Non-declarative – learning skills, habits, functions – classical conditioning
    
    • The pathway is not well understood, but it is different than the pathways for declarative memory.
      
    • You can destroy the hippocampus, and the person will not have any type of memory, but you can give that person piano lessons, and they will be able to play the piano but not remember having taken lessons.
      
    • (ex. Taxi – Christopher Lloyd as Jim Ingatowski – Elane worked at art gallery - invited Jim….piano player never showed…Jim played…burned brain out by drugs – "Damn I must have taken lessons") – this could possibly happen if you had destruction of your Hippocampus
      
  • Declarative – (is what you think of as memory) people, places, events, facts of science, what happened, what events just occurred. These memories must pass through the Hippocampus before being recorded in the Cerebral Cortex.  A memory is recorded in a specific area (if you smelled something it is stored in the olfactory cortex, or if you saw something it is stored in the visual cortex, but it has to pass through the Hippocampus.  Declarative memory has 3 parts: (these names vary by year)
    
    • 1.) Immediate Buffer – this is what you are currently using. It is a constant firing circuit or groups of circuits.  Information is entered by adjusting the firing rate of the circuits.  You lose stuff all the time out of the immediate buffer. 
      
    • 2.) Short-term memory – is going to last for a few hours.  What happens is a synapse is firing briefly at a high frequency, and the receiving neuron will become more sensitive to that firing. The receiving neurons temporarily experience a greater voltage swing in response to the firing.  It is a local response and it does not involve the nucleus. The changes to the synapse (synaptic plasticity) will last hours.
      
    • 3.) Long-term memory – memory enters in a short term memory, but instead of only being stimulated once, a few minutes later a second burst will occur, and then a third burst will occur – these are called Temporal Firing Patterns (patterns of rapid firing bursts as they are coming in).  These repeated bursts stimulate action potentials to open Calcium channels, and Calcium influxes into the target neuron. The Calcium ions will activate Protein Kinases.  The temporal firings, temporal firing patterns, and the timing of the bursts set up a chemically responsive pathway to the nucleus. Variations in these temporal patterns and timings set up different pathways, but if we are trying to set up long term memory the Calcium ions will activate a Protein Kinase that activates a cyclic AMP response element binding protein called CREB. CREB will go into the nucleus to activate genes and produce synaptic strengthening proteins. The synaptic changes are permanent and we have long term memory.  This is no the only thing that the neuron can do, a lot of things can occur by changing the temporal firing patterns. How the Calcium influxes makes a difference too. Some of the stuff comes in and makes a permanent memory, but some of the stuff (that you didn't want to remember or stuff that you are not aware of) associated with that also might be committed to memory.
      
    • This neuron can be taught to different things by changing the temporal firing patterns.
      
  • Our memories are NOT that good – it is so easy to put false memories into someone's head.
    
    • Imprinting false memories is very easy to do.
      
    • Generally traumatic memories are the ones that last.
      
      • Ex. Where were you last week vs. Where were you on 9/11.
        
      • If we have a beer party and we videotaped it.  Group A met up 6 months later, and so did Group B (to recall what happened at the party).  But Group B had a Shill (someone who wasn't at the party) in their group placing a false memory.  At the 6 month mark the Group B did not agree with the Shill who said that he threw up.  But if Group B comes back in a year, ½ of the group will remember that the Shill threw up at the party.
        

 
 

Blood Cells:

• Blood production is called Hematopoiesis
  
• You didn't start to make blood originally, b/c you were in utero at around the 3^rd week.
  
• We will cover where blood production begins (at the organ), when it wanes (when it goes away from that location)
  
• When in vivo (in utero), and you first started to produce blood – it was produced in the Yolk sac and that began at about the 3^rd week of gestation and waned from the Yolk sac at about the 3^rd month.
  
• Blood is then produced by the Vasculature (blood vessels) – this begins in about the 2^nd month and wanes at about the 5^th month, not exactly sure when it ends.
  
  • The cells creating blood in the vasculature have migrated from the Yolk sac.
    
• When we talk about a new place producing blood, indication that another true migration has begun.
  
• The Liver starts to produce blood late in the 2^nd month and wanes at about the 7^th or 8^th month. The liver is the main producer of fetal blood in the middle trimester of gestation.
  
• The Spleen starts to produce blood in the 3^rd month and wanes in 7^th month.
  
• The Bone marrow starts to produce blood in the 4^th month and ends Post-mortim (it is still going on now).
  
• When we are first making this blood we are only making Red Blood Cells (RBC's), until about the 4^th month the RBC's are larger, about 10um in diameter, are nucleated, and contain a different type of hemoglobin, from the 4^th month on they are replaced with adult type RBC's, little sacs of 8.6um in diameter hemoglobin.
  
• At about 3 months of gestation, Platelet production will occur (deals with blood coagulation).
  
• At about 5 months of gestation, Leukocytes (White Blood Cells) begin to be produced, but an immune response does not occur – they are not functional.
  
  • The Immune system does not start functioning (carrying out an immune response) until 60 days after you are born (ex. true for humans and horses).
    
    • For a Foal, the antibodies do not cross the placenta so that Foal does not have an immune system for 60 days.  It is very important for the Foal to get milk in order to get antibodies from the mother. 
      
    • In humans, the IGG (immunoglobin) will cross the placenta, and the baby will get antibodies from the mother when it is born, and the immune response will be from those antibodies to fight things until 60 days pass and it can do an immune response itself.
      
• Red Bone Marrow – when you were born virtually every bone in your body was Red Bone Marrow and it was making blood, but now that you are older blood is only being made in your:
  
  • Proximal Humerous
    
  • Proximal Femur
    
  • Shoulder Girdle (clavicle and scapula)
    
  • Pelvic Girdle
    
  • Axial Skeleton (Rib cage, head, spinal column) – centralized part
    
  • Red Bone Marrow is the largest and most active organs in your body – if we put all of your bone marrow together as a single organ it would rival the size of the liver.
    
  • The lower limbs (ex. shins) and lower arms (ex. hands), are not making any RBC's.
    
  • Since the baby has all of this, they can replace blood almost at the same rate as an adult human (it will replace 5cc's of blood just as fast as an adult).
    
  • Red Bone Marrow is NOT liquid – it is a solid tissue with zones of different types of blood cell production; each zone produces a single type of blood cell, and the zones are held together byAdhesion Molecules.
    
  • All of our blood cells come from a stem cell called a Pluripotent Hemotopoietic Stem Cell (HSC).
    
    • Pluripotent means it can become any cell it wants to become
      
  • The HSC can:
    
    • 1.) Replace itself producing another HSC cell
      
    • 2.) Give rise to Colony Forming Unit cells (CFU-L) (the L stands for Lymphocytes) – the CFU-L is not a lymphocyte but it is destined become one
      
    • 3.) Can produce a cell called CFU-GEMM – this cell can become all the other blood cells that you make
      

       
       

 
 

Lecture 13

Regulation of Meal Intake and Weight Regulation, continued

 
 

• The Hypothalamus has a Feeding Center and a Satiety Center.
  
  • Lateral-Hypothalamic Nuclei – Feeding Center.
    
    • It is saying eat; it creates a hunger sensation.  It is constantly telling you to eat.
      
  • Ventro-medial Nuclei – Satiety Center.
    
    • It tells the Feeding Center to shut-up.
      
    • It works; the feeding center shuts up when it is told to.
      
    • The Satiety Center bases what it says to the Feeding center on many physical parameters that it is monitoring.
      
      • In the blood it monitors the uptake of glucose by cells.  It does this by monitoring the amount of glucose in the blood of the atria and compares it to the amount there is in the veins.
        
        • When glucose is being taken up, it puts a positive into the Satiety Center, which will then send its message to tell the Feeding center to shut up (putting negatives into the Feeding Center).
          
      • High Amino Acid (AA) and Lipid levels stimulate the Satiety center.
        
      • In the GI tract there are Stretch Receptors – they indicate the amount of food there is in the GI tract and if they are stretched they stimulate the Satiety Center.
        
      • Also in the GI tract, we are going to monitor the levels of glucose, protein, and fat.
        
      • Glucose is monitored directly with their own glucose receptors in the gut (the more glucose we have the more we stimulate the Satiety Center)
        
      • Protein and the fats are monitored indirectly and are going to stimulate a hormone called CCK.  CCK is monitored by the Satiety Center of the Hypothalamus (if you eat proteins or fats it increases CCK)  
        
    • We used to look for a set point for the Satiety center, but it is the Feeding Center that is the set point.
      
      • The Feeding Center is receiving all of this physiological input, but it ignores it, and the Feeding Center just sits there and says I will do whatever the Satiety Center tells me to do
        
      • If the Feeding Center is destroyed, you will become obese but up to a new level.
        
      • The feeding center is a slave of the satiety center.
        
      • The things being monitored here are all based upon metabolites and volume in the gut
        
    • This is a short term meal system
      

 
 

 
 

• Weight Regulation:
  
  • Meal intake is part of Weight Regulation System – (the Ventral Medial Nuclei and the Lateral-Hypothalamic Nuclei are functioning with this Weight Regulation System
    
  • These are all in the nuclei of the Hypothalamus
    
    • Paraventricular – sits on either side of the 3^rd ventricle, and there are 2 of them
      
    • Dorsal-medial nuclei – sits on either side of the 3^rd ventricle, and there are 2 of them
      
    • Arcuate nucleus – is the only single nuclei, b/c it sits below the 3^rd ventricle
      
  • The main regulator of body weight is a hormone that is produce by Adipocytes (fat cells) called Leptin.
    
    • The more adipose fat tissue you have the higher the level of Leptin you produce, and vice versa.
      
    • Leptin receptors are found in all of the Hypothalamic nuclei (they are regulating the weight)
      
    • The 3 nuclei above all have receptors for Leptin.
      
    • If we have high levels of Leptin causes:
      
      • A reduction in your Feed Intake
        
      • A stimulation of catabolism of fat (breaking something down)
        
      • An increase in the Basal Metabolic Rate (BMR) (this increases the amount of calories that you are burning)
        
    • Low levels of Leptin have exactly the opposite effect:
      
      • Anabolism of fat
        
      • Increases Food Intake
        
      • Decrease BMR.
        

Water Balance System in the Hypothalamus

• Balance means that intake has to equal output. This is done by the Hypothalamus.
  
  • Water balance levels are set to maintain:
    
    • Blood volume
      
    • Blood pressure
      
    • Osmotic gradient of the plasma
      
  • Intake of water is regulated by Thirst.
    
  • Output of water is regulated by ADH (Anti-Diuretic Hormone) – is a hormone that when stimulated causes the kidneys to reabsorbe more water thus lowering your urine output
    
• Thirst:
  
  • The osmotic receptors located in the Anterior Hypothalamus that monitor the osmotic gradient of the plasma.
    
  • The osmotic receptors themselves are just cells that shrink in response to a high osmotic gradient (they swell in a low osmotic gradient).
    
    • When they shrink they are lacking water 
      
    • When they swell they are full of water.
      
  • When the gradient is high, meaning there is lots of salt in your body (NaCl is the main one we look at) the receptors will stimulate the thirst center in the Lateral Hypothalamus (they say get thirsty)
    
    • Thirst Center  + or - (puts in) Osmotic gradient.
      
    • When positives are put in, it is a dryness of the mouth.
      
  • The stomach does not absorb water, which is why you get full when you drink water. 
    
  • The main site of water re-absorption is the Duodenum.
    
  • If there is food in the stomach the fluid can get into the small intestine rather quickly because it bypasses the bolus of food. This is because the stomach contracts and relaxes around the food (putting the food in the center), and allows spaces/a pathway for the fluid to get by, into the small intestine.
    
  • There are receptors in your Pharynx, Stomach, and Hepatic portal vein – when these are stimulated by water, to say you cannot drink anymore.
    
    • You drink water b/c water hit the osmotic receptors of the pharynx, stomach, and hepatic portal vein and then they will equalize and you will get another drink of water (you continue to do this until the osmotic receptors say that's enough)
      
  • None of that water has gotten to the osmotic gradient receptor in the hypothalamus.
    
  • GI Tract Osmotic Receptors – put in a negative and send it to the thirst center – you are no longer thirsty. They can only put in a positive.
    
  • You keep getting thirsty and then stopping, until the osmotic gradient drops to where you don't drink for a while.
    
    • This prevents you from drinking too much water.
      
  • These receptors can be fooled with Gatorade, which changes the osmotic gradient, so you can drink a lot of it quickly. Gatorade can easily bypass those receptors b/c that is what they are set to do (you can drink a lot more Gatorade than water)
    
• When you give a pint of blood and you get thirsty, this is called Hypovolemia – (means low volume blood) – drop in blood volume.
  
  • 2 things are working here and are monitored by the hypothalamus
    
  • 1.) Angiotensin II – this is a powerful blood pressure raiser monitored by the hypothalamus, and it comes from the kidney and secrets Renin.  The Renin will change to Angiotensin I, which will change to Angiotensin II.  If you raise the Angiotensin II levels it will increase the levels of the thirst b/c you are trying to raise your blood pressure (you do this by drinking more).
    
  • 2.) Baroreceptors – this is a pressure receptor.  The Baroreceptors in the atria of the heart monitor the blood volume that is sitting in the veins.  Baroreceptors found in your carotid sinusand that monitor the blood pressure.
    
    • Increasing the firing rates of the Baroreceptors (that is increasing the blood pressure and volume of blood) will reduce the thirst
      
      • This means that a high angiotensin II levels and high osmolatiy of plasma increase ADH. This increases absorption of water by the kidney and lessens your urine output.
        
    • If we have a drop in volume or blood pressure, this will increase the thirst
      
• There a lots of social reasons for drinking.
  
  • When you drink beer it blocks ADH, which tells you kidneys to stop producing ADH (ADH tells kidneys to reabsorb water) – this increases your urine output.
    

 
 

Regulation of Body Temperature:

• There are Thermoreceptors in the pre-optic area of the Hypothalamus.
  
  • These receptors monitor the temperature of the blood.
    
• Normal body temperature is 37C– this is 98F
  
• There are Heat Sensitive Neurons in the Hypothalamus.
  
  • They increase their firing rate when the temperature goes above 37C.
    
• There are Cold Sensitive Neurons in the Hypothalamus
  
  • They increase their firing rate when the temperature goes below 37C.
    
• The hypothalamus gets input from the skin from its hot and cold receptors.
  
• Input also comes from the blood.
  
• When the hypothalamus and skin receptors contradict each other, the hypothalamus will override the peripheral receptors and make the appropriate response.
  
• Response to the cold is mainly due to peripheral receptor stimulation while response to heat stimulation is due to hypothalamic stimulation, this is why you have more cold receptors in the skin, and more heat receptors in the hypothalamus.
  
• Response to a cold environment:
  
  • Increase your chemical heat production by:
    
    • Shivering
      
    • Increase your voluntary activity.
      
    • Eat – eating not only increases the amount of metabolites that you can burn to keep warm, but eating also has a Specific Heat of Digestion (there is a certain amount of heat that is produced by your body digesting your food).  
      
      • In the winter, the specific heat of digestion is conserved and used for heat.
        
      • In the summer, the specific heat of digestion is lost as radiant heat (you don't use this heat). 
        
    • Increase the Circulating Catecholamines, which have a calorigenic effect on the body.
      
    • Increase our metabolism of our body – this occurs every winter.
      
    • Stimulate your Brown Adipose Tissue (BAT) – Brown Fat.
      
      • A brown adipocyte is a small globule (brown thing) that the burns a lot of fat quickly.
        
      • A normal adipocyte is huge and filled with a lot of fat (white).
        
      • Babies have a large amount of BAT b/c they lose a lot of heat.  They have a large surface area compared to their volume of weight
        
      • When born, there is BAT in the back of your neck and a small part of back
        
      • When you get to be older, all of this disappears, it is still brown adipose tissue but it looks like white adipose tissue.
        
      • If you are exposed over and over to the cold environment the BAT changes back to a type that will function to produce heat.
        
      • If you are exposed to the cold over and over again, it will cycle to the functional form much quicker.
        
      • The more frequent it cycles, the quicker it will cycle back to a functional form.  Once you stimulate it, it will keep on being stimulated.
        
      • There is a protein in the mitochondrial membrane of these cells called Thermogenin
        
      • Electron transport chain – generally burning Hydrogen to create ATP.
        
      • Thermogenin uncouples Oxidative Phosphorylation from ATP production and all the energy is used for heat.
        
  • Decrease heat loss in the cold by:
    
    • Increasing Cutaneous Vasoconstriction – blood vessels beneath skin constrict (don't want to lose the heat in your blood).
      
    • Reduce your surface area – you do this by curling up.
      
    • Haripilation – it stands the hair up – it increase the R value of the hair insulation purposes (in humans this is called Goosebumps, but it is more useful for animals (ex. Dogs) by increasing their insulation ability and decreases their heat loss)
      
      • R-value is how much heat loss is occurring as a function of the hair standing up.
        
• Response to a hot environment:
  
  • Decrease heat production by:
    
    • Anorexia – eat less
      
    • Become inert and docile –less activity
      
    • Lower BMR
      
    • Inhibit BAT – a non-functional form.
      
  • Increase Heat Loss by:
    
    • Cutaneous Vasodilation – loss of heat
      
    • Sweat – as it evaporates, it takes heat from our bodies.
      
    • Increase respirations – the air that you breath is usually cooler than what comes out so you can increase respiration – that increases heat loss.
      

 
 

Lecture 12

Posture and Movement, continued…

 
 

• Caudate Circuit:
  
  • Prefrontal  Premotor  Supplementary motor  Somatosensory  Caudate  Putamen  Globus pallidus
    
    • The Globus Pallidus sends information to the Thalamus.
      
    • The Thalamus will send it back to the Prefrontal and Premotor
      
      • The circuit does not send information to the Primary-Motor cortex because every movement you make has been made before.
        
    • The Caudate Circuit does not plan the movements; you do not have any movements that you have not done before in your life.
      
    • There is a library of movements that are all subconscious.
      
    • This circuit is taking the movements off of the library shelf. You select the patterns of already learned Subconscious motions.
      
    • When you initiate the Subconscious motion – the Caudate Circuit initiates the order in which it should be done.
      
    • Pre-motor also talks to the Neocerebellum (more lateral portion of the cerebellum), which signals back to the Premotor and Supplementary.
      
    • The Neocerebellum is working on the next sequential movement, it is one step ahead.
      

       
       

 

• Movement Execution: performed by the Primary Motor Cortex
  
• The Primary Motor Cortex sends messages from the Upper Motor Neuron to the Lower Motor Neuron, which will go down to the muscle, thus initiating the movement of skeletal muscle
  
  • The Spinocerebellum (in the Basilar Pons) – when the Primary motor cortex sends a message through the Pons to the lower motor neuron it also sends a message to the Spinocerebellum. The Spinocerebellum monitors what information is being sent and it can send corrections back to whatever he thinks might be wrong.
    
    • The Primary Motor Cortex sent a map of what was going on to the Spinocerebellum, which talks back to the Primary Motor Cortex
      
  • The Spinocerebellum sends corrections of its own through the Red Nucleus to the lower motor neuron.
    
    • What the Red Nucleus (in the midbrain) is passing on is monitored by the Spinocerebellum
      
      • A Camel is a horse designed by a committee
        
  • The Neocerebellum is working on the next movement down
    
  • The Floccularnodular Lobe (smallest) – is in contact with Neocerebellum and Spinocerebellum as to equilibrium. They are in connection from the inner ear.
    
    • The Floccularnodular Lobe is working on quicker and more intricate movements that include changes in direction.
      
  • If we make a quick movement that it bypasses the Spinocerebellum (not giving the Spinocerebellum a chance to correct the movement), which is called a Ballistic movement – it will overshoot the target because it does not have a chance to be corrected.
    
    • Ex. Move finger towards the exit fast your arm has a pendulum action (the Spinocerebellum didn't have time to correct it), but if he does it slowly it doesn't waver
      

 
 

Medullary Autonomic Reflex Centers:

• The medulla is the regulator of some fairly complex autonomic nervous system reflexes.
  
• These are also known as Life Centers
  
• 1.) Swallowing:
  
  • Swallowing can be initiated on a Voluntary basis, but it is not always done this way, you are always creating a certain amount of saliva in your mouth and you don't think about it. Once it is started it is finished by an Autonomic reflex.
    
  • The Voluntary stage consists of the tongue pushing upward and backwards.
    
  • Moves the bolus of food into the Oropharynx.
    
  • The uvula pulls the Soft pallet over the nasophayrnx and seals off the nasopharynx so food does not go up your nose.
    
  • Receptors in surrounding epithelium signal the brain and autonomic portion of swallowing starts.
    
  • The vocal cords close and the rise up tightly next to the epiglottis (covering the opening of the larynx) making a tight seal. This shuts off the trachea (which is anterior to the esophagus) so that food doesn't go down this way.
    
  • Respiration is reflexively inhibited.
    
  • The Upper sphincter of the esophagus relaxes.
    
  • The Superior constrictor muscles of the pharynx start a peristaltic contraction.
    
  • This pushes the bolus of food into the esophagus, through the relaxed esophageal sphincter. Peristaltic contractions push the food into the stomach.
    
• 2.) Coughing –
  
  • Coughing is initiated by the irritation of receptors in the pulmonary airways.
    
  • First take a deep breath
    
  • The epiglottis closes and vocal cords push up against the epiglottis and seal off the trachea.
    
  • The Trachialis muscle contracts making the trachea narrower and increases the velocity of the air exiting.
    
  • Intrapulmonary pressure builds, the epiglottis and the vocal cords open quickly and a blast of air comes out through your mouth.
    
• 3.) Sneezing –
  
  • Sneezing is initiated by irritation receptors in the nasal cavity and the nasopharynx
    
  • Similar to cough but the air is directed through your nose.
    
  • The purpose of coughing and sneezing is airway clearance.
    
• 4.) Gagging –
  
  • Gagging is initiated by Oropharyngeal irritation to the point of airway blockage.
    
    • When you stick your finger down your throat to throw up, they will gag, but this is not only due to the irritation receptors but it is always b/c they are blocking their airway when they are doing that
      
• 5.) Vomiting –
  
  • Vomiting is initiated by irritation receptors in the upper GI tract and by chemical receptors (chemoreceptors) in the medulla.
    
  • Reverse peristalsis of the upper GI tract
    
  • Function to empty the stomach.
    

 
 

Homeostasis in the Hypothalamus –

• keeps something normal – maintenance of the body
  
  • ie weight...
    
• http://en.wikipedia.org/wiki/Hypothalmus
  
  
• Hypothalamus plays a role in:
  
  • Sympathetic and Parasympathetic responses.
    
  • It is an integral part of RAS and Limbic system
    
  • It is a part of cyclic behavior.
    
• The Circadian Clock – about a day clock.
  
  • It is located in the Supra-Chiasmatic Nuclei – there are 2 of them
    
    • Each has approximately 10,000 cells and they all function independently of one another.
      
    • Each cell is a clock and it works on the gene level.
      
  • The first gene is called Clock and it makes a protein called Clock.
    

Gene	Protein Produced	Gene Stimulated	Protein Produced
Clock	Clock
BMAL-1	BMAL-1
	Clock + BMAL-1 together	Cryptochrome	CRY
	Clock + BMAL-1 together	Period	PER

• Clock produced all the time (Clock is very easy to find)
  
• BMAL-1 must be stimulated to be produced, so it takes a while to be produced. (It is not made all the time, it must be stimulated)
  
• Clock and BMAL-1 form a heterodimer, and then function as a single protein.
  
  • Together they activate 2 genes – Cryptochrome and Period
    
    • Clock has to get into the nucleus to stimulate these genes.
      
    • As a heterodimer it puts in positive and
      
• CRY and PER bind together to get back into the nucleus, CRY can do it alone, but PER cannot. But once it is in the nucleus, they split apart.
  
  • CRY turns off the heterodimer. This occurs quickly. This is a Negative Feedback System.
    
  • PER helps to slowly stimulate (be positive on) BMAL-1 production.
    
• This on and off cycle will occur in 25 hours, if they are put in a cave where there is nothing (no light whatsoever). They will only be off by one hour each day.
  
• The Circadian clock is corrected to 24 hours by the input of light. This is b/c each of the 10,000 cells (there are 20,000 cells if you count both of the Super-Chiasmatic nuclei) b/c everything is synchronized with the light.
  
• Some of the retinal ganglionic cells go directly to the Supra-Chiasmatic Nuclei
  (SCN) (they don't go to the LGN) – this is referred to as the Retinal-Hypothalamic Tract.
  
  • The ganglion cells of the SCN are releasing Glutamate on the cells, in response to light stimulation (of the rods and cones of the retina)
    
  • The Glutamate can only affect the circadian clock during the phase when the Cryptchrome and the Period are turned off.
    
  • When the Cryptchrome and Period are turned off it is considered to be Circadian Nighttime.
    
  • Light stimulation early in the Circadian Night will move the clock back.
    
  • Light stimulation late in the Circadian Night will move the clock forward.
    
  • Both of these are stimulated by Glutamate but different receptors are involved.
    
  • These corrections resync the clock to 24 hours.
    
  • All 10,000 cells are synchronized because they all received the same light input.
    
  • Both Super-Chaismatic Nuclei are receiving the same light input so they are synchronized together.
    
  • This correction is mainly due to rods and cones, but it can happen in the absence of rods and cones.
    
  • There is a certain ganglion cell (not rods or cones) that has a photopigment called Melonopsin – (this protein can detect a Diffuse light) this is how people do the regulation without rods and cones (blind people). This pigment is in the ganglion cell itself, not in the retina.
    
    • Melanopsin does a very poor job of doing that, and it takes it much longer to reset it with this. It is the light from the rods and cones that is resetting the clock.
      
• The output of the SCN is both electrical and chemical. During Circadian Daytime (heterodimer is active) the SCN will increase its firing rate and is also secreting a signaling protein called Prokineticin 2.
  
  • Increases the amount of Prokineticin 2 it makes during the Circadian Daytime and decreases the amount during the Circadian Nighttime.
    
    • Prokineticin 2 stays within the CNS it only works within the brain.
      
    • The high electrical activity and high production of Prokineticin 2 works the same for Nocturnal (animals that are night active) and Diurnal (animals that sleep at night) animals.
      
      • This is the main clock in our head; it is the one that we worry about resetting. (Jet Lag)
        

• The other body clocks in our body is in our peripheral tissues
  
  
  • These similar clocks are in the
    
    • 1.) Kidney
      
    • 2.) Liver
      
    • 3.) Heart
      
    • 4.) Vasculature
      
  • They are all gene clocks that work in a similar fashion to the SCN circadian clock, but they do not have any direct retina input to reset them; rather they rely on hormone levels to keep them regulated/reset.
    
  • All the peripheral clocks use Clock as a constant level protein of the heterodimer.
    
  • The cyclic protein in all these areas can be BMAL-1 or MOP-4, or some other cyclic protein.
    
  • The variations of the cyclic proteins allow specificity of hormone clock resetting.
    
  • The Peripheral clocks are usually 3 to 9 hours out of sync with the SCN.
    

  Regulation of Meal Intake and Weight Regulation
  

  • Meal Intake – is a short-term homeostatic system; how hungry are you, how much are you going to eat, what makes you start and stop eating (it works on a one meal basis)
    
  • Weight Regulation – is a long-term homeostatic system; how we are going to maintain our stable weight (cycling from the morning to night)
    
    • You weigh the least in the morning and by the time you have gone through the day you will gain 5 pounds, but then you will lose it back again (after a heavy meal you weight more, but when you go to the bathroom you lose weight)
      
    • You will stay within this 5 pound range day after day
      

   
   

   
   

   
   

Lecture 11

• EEG
  
  •  Electroencephalogram:
    
    • It monitors the superficial electrical activity of the cerebral cortex. You can't see what the hypothalamus is doing. Electrodes are placed on the scalp itself.
      
    • ECoG – Electrocorticogram. [NOW: ECG old: EKG (Electrocardiogram)-put electrodes on the head.]
      
      • The electrodes are placed directly on the brain (in the ECoG).
        
    • Electrodes are placed on reference points (landmarks) from the Nasion (where nasal suture meets frontal suture) to the Inion (on the external occipital protuberance).  Standardized so it will work on children and adults.
      
    • We place 11 electrodes from the Nasion to the Inion to divide the scalp into 10 equal spaces. To get this you draw a line from Naison to Inion
      
    • SEE HANDOUT of EEG locations (not given HO)
      
    • In front of the opening to the ear, there is a notch – There are 2 Pre-auricular points. From pre-auricular point to pre-auricular point is divided into 10 equal spaces.
      

       
       

    • Modified Combinatorial system – all the possible placements of EEG electrodes on the head.
      

       
       

      • There are 11 positions.
        
        • z = zero, dead center
          
        • The Right hand side of the person is even numbers
          
        • The Left hand side of the person is odd numbers
          
        • N = Nasion
          
        • FPz = pre-frontal
          
        • AF = anterior frontal
          
        • F = frontal
          
        • FC = frontal, central
          
        • C = central
          
        • A1, and A2 – auricular, hang on earlobes, grounding electrodes (these don't count). 
          
        • T9 and T10 = Temporal, and are the Pre-auricular points. There will be 11 of them (dividing 10 equal spaces)
          
        • FT = frontal temporal
          
        • CP = central parietal
          
        • P = parietal
          
        • PO = Parietal Occipital
          
        • O = occipital
          
        • I = inion
          
      • People who have brain damage, will have different places where you want to put leads for the EEG. If someone got shot in the head and they lose part of their brain and you do EEGs around the area, they might have Strange Montages.
        

       
       

    • The 10-20 System is what they do for a normal person, if you are conscious.  This is the standard set up for EEG (called 10-20 b/c instead of 10%, you are getting 20% in some of the electrodes). It is based on equal spacing so there is no such thing as a child EKG and adult EKG.
      
      • These are for strictly Unipolar Readings
        
      • There are 16 leads.
        
        • We don't put electrodes on Fz, Pz, or Cz.  We don't monitor these
          
          • Because its between hemispheres
            
        • PG1 and PG2 – grounding posts placed on either side of your nose.
          
        • A1 and A2 – there are alligator clips on the ear lobes used for grounding
          

           
           

  • Two Types of Recordings:
    
    • Bipolar Recording – it is hooked to two electrodes and you measure the difference between the 2 (the electrical flow is going in one direction if positive). 
      
      • You can measure the electrical difference from north to south or from east to west (they can't go diagonal).
        
      • Don't do them here, but a lot in Europe
        
    • Unipolar Recording – the electrodes are set up like a bipolar reading.  We have 2 electrodes reading, but 1 is placed on an area where we won't see electrical activity (we are always working against/comparing the electrode with electrical activity to the null/void electrode). Essentially all we see is the unipolar. It is comparing it to a non-electrical event.
      
    • In America we only use Unipolar EEG's because they give nicer waves and are easier to read.
      
    • In Europe they use Bipolar EEG's almost exclusively because they give nicer waves and they are easier to read.
      

       
       

  • If we set up electrodes for this Modified Combinatorial System, they have to go in the same direction. This would mean that all the other electrodes would have to be going across in this plane. They have to go from left to right or front to back.
    

     
     

  • The grounds are put on your nose because it is cartilage, and you won't get excess electrical activity (there is no muscle here)
    

     
     

  • A Montage, is a list of bipolar leads that you actually monitor, which means that they are Bipolar Readings.
    
    • If we have Unipolar readings it is called a Referential Montage, which is referenced to the ground, and the machine is set so it will find the electrode that has the least amount of electrical activity going to it, and it will compare that electrode to the electrode that is grounded (i.e. the reference point being the null or void).
      
  • The Standard Waves of an EEG: (never written in the Greek Sign)
    
    • http://en.wikipedia.org/wiki/Electroencephalography#Wave_patterns
      
    • Alpha Wave 
      
      • 8 – 13 Hz in frequency (how often it goes up and down)
        
      • approximately 50mv in amplitude (how tall it is).
        
    • Beta Wave 
      
      • > 13 Hz
        
      • They have a greater frequency but they usually have a lesser amplitude than an alpha wave.
        
    • Theta Wave 
      
      • 4hz < 8hz
        
      • Higher amplitude than alpha waves.
        
    • Delta Wave 
      
      • < 4 Hz
        
      • Very high in amplitude.
        
    • We have some unofficial waves:
      
      • Gamma Wave – used to be considered greater than 30 Hz but they are now considered part of the Beta Waves.
        
      • Zeta Wave – abnormal wave of some sort, means nothing.
        

         
         

    • Alpha rhythm
      
      • are a series of repeating alpha waves.
        
      • occur when you are completely and totally relaxed, and your mind is blank. This is a non-alert state.
        
        • Resting with your eyes closed, but if someone were to do a stimulus you would go into Beta Waves – you would be relaxed and alert.  This is called Alpha Blocking.
          
        • Alpha rhythm is never found in the anterior of the brain.
          
        • Alpha waves are found over the:
          
          • occipital lobe,
            
          • parietal lobe,
            
          • The posterior half of the temporal lobe
            
        • Once in a while you will find an alpha rhythm in 10% of people called a Central Mu Rhythm, which is over the Pre-central Gyrus where you are getting movement messages – but it goes away when people move.
          

         
         

• Sleep 
  
  • comes in 4 stages (we only have done research on graduate students, so we only know how graduate students sleep)
    
  • http://en.wikipedia.org/wiki/Sleep#Physiology
    
    • Stage 1 –
      
      • you are just lying down, you start in Alpha Rhythm.  You are Awake lying calmly not asleep, just relaxed with a blank mind)
        
      • When the alpha rhythm starts to elongate (slowing to 2 to 7Hz and drops slightly in amplitude), you have moved into Stage 1 sleep.
        
      • You do not go directly in to REM, you come up to REM from lower stages.
        
      • Vital signs– 1.) Pulse, 2.) Blood pressure, 3.) Respiration, and 4.) Temperature – stay normal, and person is easily aroused, but may deny that they were asleep, they have not lost their awareness. This is only true in some people.
        
      • When the alpha rhythm gets very jumpy up and down (lots of noise), it is referred to as a: 
        
      • Sleep Spindle – 7 to 14hz, and it will be higher in amplitude than an Alpha wave.
        
        • The first Sleep Spindle that appears is a sign that the person has gone into Stage 2 sleep.
          
    • Stage 2 –
      
      • Sleep Spindles increase in number slowly
        
      • The person has lost perceptual awareness, and is not easily aroused.
        
      • Vital signs are still normal.
        
    • Stage 3 –
      
      • Sleep Spindles begin to disappear (decrease in number).
        
      • The waves that are between the Spindles start to increase in amplitude and lower in frequency
        
      • Vital signs begin to decline.
        
      • Finally the Spindles disappear all together, and all that is left is a very large Delta wave.
        
    • Stage 4 –
      
      • Once the Sleep Spindles have disappeared completely, all we have are Delta waves.
        
      • The Delta wave is produced by the Thalamus. The thalamus gets its instructions from the RAS system.
        
      • You are going to cycle out of Stage 4 sleep in the middle of the night, and then we are going to get a stair step into REM sleep. 
        
      • Stair step all the way from awake, 1, 2, 3, 4, 3, 2, 1, REM
        
    • REM (Rapid Eye Movement) Sleep is considered to be a more awake pattern of sleep where you are dreaming (more of less we have Beta waves). 
      
      • You can do an EOG, which monitors the muscles of the eye, and your eyes are flipping back and forth.  The EOG can monitor when you are dreaming.
        
      • Then you are going to cycle back down (you might go from Stage 3 to Stage 1 immediately, so it is not always a stair step process)
        

         
         

    • The pattern that is formed is called a Sleep cycle (that is from peak to valley)
      
      • http://www.ultracrepidate.com/wp-content/uploads/2007/01/sleep_cycle.jpg
        
      • You have 4 to 6 sleep cycles a night (for 20 yr. olds),
        
      • Not all of the stages are visited and there are different durations that you stay in a stage for.
        
      • If you are elderly, you have fewer cycles per night, and when you are really old, you stop going into Stage 4 (Stage 4 is needed, and that is why elderly people fall asleep in front of the TV/during the day) – they have fewer sleep cycles.
        
    • You do not remember a dream unless you wake up during REM.
      
    • If a person is deprived of Stage 4 sleep, they will spend more time in Stage 4 the next time they get down to Stage 4.
      
    • If you are deprived of REM sleep, they will go back into REM more quickly the next time the sleep cycle comes around.
      
    • If someone is totally derived of REM sleep – the person will become emotionally unstable and exhibit various personality disorders until they are allowed to get REM sleep again.
      
    • Dreaming 4-5 times per night, but only remember the ones that you wake up to…
      
• Posture and Movement
  
  • Posture:
    
    • Posture is Reflexive. It is maintained by a series of reflexive actions. They are learned reflexes.
      
      • You learned this when you are little kid, now you don't think about what you are doing. You have a learning process (ex. Picking up a Foal to get it to walk faster)
        
      • Static Reflexes for Posture – are sustained muscle contractions to maintain the position of the body (if you extend your arm you have to flex more back muscles to hold something than if you held a weight close to your body – physics)
        
      • Phasic Reflexes for Posture– are movement reflexes, they are short-term movement or stance corrections (ex. If you push someone, they brace themselves in response to being pushed – hop on one foot to readjust)
        
      • Medullary Reflexes – those regulated by the Medualla oblongata.
        
  • Movement:
    
    • Putamen Circuit: (subconscious motion)
      
      • Subconscious Motion – these are motions that you don't think about, you just do them (such as reflexes)
        
    • Pre-Motor  Supplementary Motor --> Somatosensory Area (which goes into the post central gyrus and has to do with proprioception). 
      
      • These 3 make a plan for the motion what they want to do, and then they send this information to the Putamen.
        
      • The Putamen sends the information to the Globus Pallidus.
        
      • The Globus Pallidus sends the information to:
        
        • 1.) The Substantia Nigra (in the midbrain) – doesn't talk back
          
        • 2.) The Subthalamic Nuclei – talks back.
          
        • 3.) The Thalamus
          
    • Globus Pallidus, Substantia Nigra, and Subthalamic Nuclei send info to the Thalamus.
      
      • EVERYTHING Talks to the Thalamus
        
    • The Thalamus sends information back to the:
      
      •  Primary Motor Cortex (in the pre-central gyrus)
        
      •  Pre-Motor Cortex (with supplementary motor and somatosensory)
        
      • The Primary-Motor Cortex initiates the movement and will initiate the cortex.
        

         
         

    • Cognitive Movement (you decide you are going to make a motion)
      

       
       

       
       

      FRIDAYYYY
      

   
   

   
   

   
   

Lecture 10

Autonomic Nervous System 

 
 

1. The Autonomic Nervous System:
   
   1. Sympathetic Nervous System
      
   2. Para-sympathetic Nervous Systems 
      

       
       

• They both have a system of the upper motor neurons going to pre-synaptic neurons and post-synaptic neurons (and then go to the target tissue) in place of the lower motor neuron (note: upper motor neurons went to lower motor neurons in the CNS). 
  
• The Sympathetic nervous system can trace its pre-synaptic neurons to the sympathetic trunks
  
  • This is the anatomical definition of the Sympathetic nervous system
    
• The Para-sympathethic Nervous system cannot trace any of its neurons to the sympathetic trunks
  
  • This is the anatomical definition of the Para-sympathetic nervous system
    

     
     

• The two systems differ in neurotransmitters that they use at the target tissue
  
  • Pre-synaptic neurons in both Sympathetic and Parasympathetic secrete ACh (Acetylcholine)
    
  • The Parasympathetic system uses ACh at both the pre-synaptic and post-synaptic spaces
    
  • The Sympathetic uses Norepinephrine as the post-synaptic on or near the target tissue
    
  • There are 3 exceptions to this rule that the SNS uses Norepinephin
    
    • The SNS post-synaptic neurons, during flight or fight, are going to dilate the blood vessels to the skeletal muscles and use ACH. When you sit down and then stand up – your blood pressure was changed by the SNS – that is called Vasomotor Tone. When it changed the blood pressure it used Norepinephin.???At presynaptic???
      
    • Sympathetic post-synaptic neurons that innervate the Sweat Glands use ACH.
      
    • Sometimes there are no post-synaptic fibers.  When this happens the pre-synaptic fiber goes all the way to the adrenal medulla.  There the pre-synaptic fibers synapse (raining ACH out) on:
      
      • Chromaffin cells
        
        • These are endocrine cells that secrete hormones and they get released into the blood stream
          
        • Secrete things called Circulating Catecholamines - which are 80% epinephrine and 20% norepinephine
          

           
           

• The effect of the Parasympathetic system:
  

   
   

  • Constricts the pupils of the eye
    
    • it is the only one innervating the circular smooth muscles of the iris)
      
    • Contracts the ciliary muscle of the eye, which is attached to the lens of the eye. 
      
    • The lumen is getting smaller since this is a circular muscle. 
      
    • There are suspensory ligaments going to the lens, and it allows the lens to bulge (for close vision) and get fatter. 
      
    • The Sympathetic system does not innervate the ciliary muscle of the eye. 
      
  • It decreases the heart rate
    
    • When you sit down, your heart rate decreases b/c of the PNS b/c it has increased the firing rate to do that.  But when you stand up and increase your heart rate, it increases b/c of a decreasing the firing of the PNS. The SNS kicks in through regulating your heart rate, and there is a constant sending through there.  All you have to do to increase it or decrease it is change the PNS up and down.
      
  • It constricts coronary blood vessels
    
  • It increases the activity of the GI tract
    
    • it relaxes the sphincters to allow movement, it will increase the secretions, and it will increase the smooth muscle contractions in the GI tract.
      
  • It constricts the bronchioles of the lungs 
    
  • It is responsible for the contraction of the bladder, but it does not effect the kidneys (the PNS does not innervate the kidneys) 
    
  • It causes sexual excitation in both males and females
    

     
     

1. The effects of the Sympathetic system
   
   1. It dilates the pupil of the eye. 
      
      1. It innervates the radial muscles of the Iris, making the pupils larger. 
         
      2. During flight or fight, we will dilate your eyes, but when we walk into a dark room your eyes will dilate too, which is not flight or fight.  During the Sympathetic stimulation of flight or fight, if we monitor the lens of the eye, we do find that the lens of the eye does flatten some.  This is probably due to the change in the blood flow/circulation or the changing of the firing of the PNS, b/c there is no ciliary muscle to do that.
         
   2. It constricts and dilates all the necessary arteriole and venous systems for fight or flight (to accommodate for changes in the blood flow)
      
   3. It increases the heart rate, and increases the force of the heart beat. 
      
   4. It dilates the arterioles of the heart and skeletal muscle (you are thinking more about flight or fight when you do this)
      
   5. It constricts the arterioles of the:
      
      1. GI tract
         
      2. Kidney
         
      3. Skin
         
      4. Sex organs
         
   6. It constricts the arterioles to the lungs
      
      1. When running, you are expanding the lungs.  When you start to take deeper breathes, this will drop your blood pressure.  This is why we constrict our arterioles to make the blood pressure rise and stay at the proper pressure of the lungs.  You don't want your blood pressure to drop.  
         
   7. It dilates the Bronchioles of the Lungs (allowing more in)
      
   8. It shuts down the GI tract completely (this is definitely a flight or fight thing), closing sphincters, decreasing secretions, and relaxing the smooth muscle contractions.  
      
   9. It relaxes the bladder (this is not urinating) and closes the sphincter urethra (this is a flight or fight thing too)
      
   10. It increases Renin secretion by the kidney, making more Angiotensin II available giving you increased blood pressure.
       
   11. It increases sweating and pilli muscle contraction (Haripilation occurs – goosebumps)
       
   12. It stimulates fat break down in adipose tissue 
       
   13. It mobilizes glycogen stores of the liver raising blood glucose levels
       
   14. It also contracts the spleen, this does not make much of a difference in humans. 
       
       1. In larger animals, like a horse, if they contract the spleen they raise their Hemoatocrit by 5 points, because they have large stores of RBC's in the spleen. 
          
   15. Causes sexual orgasm in both male and female. 
       

• The Sympathetic system cannot shut down the sexual excitation that the Parasympathetic system created; the only way to end the excitation is through orgasm. 
  

 
 

• The sympathetic system is usually the winner over the parasympathetic system. 
  

   
   

• Sympathetic Tone – is the tonal firing of the sympathetic systems, especially the heart. 
  
  • When we talk about Sympathetic tone we only think of the Sympathetic Vasomotor tone, b/c there are no innervations of the blood vessels that are responsible for blood pressure regulation
    

     
     

• Parasympathetic Tone - is not due to the lack of Sympathetic innervations, it just sits there doing the same thing with the exception of when you have flight or fight.   
  
  • The heart has Parasympathic Tone firing and constant sympathetic tonal firing to blood vessels, increasing and decreasing tonal firing of sympathetic fibers – Sympathetic Vasomotor Tone
    
  • Regulating the blood pressure as you are walking back and forth. 
    
  • This is not in fight or flight. 
    
  • 3 systems of Parasympathetic Tone
    
    • these systems are generally regulated by the Parasympathetic system, except in the case of fight or flight. The Parasympathetic system is the ruler, unless we have fight or flight.
      
    • The heart is run by the parasympathetic system except you are in fight or flight (the PNS tells the heart to slow down and the SNS tells the heart to speed up: they are on both sides of the SA node)
      
    • The GI tract is under parasympathetic control except in fight or flight
      
    • The bladder is controlled parasympathtically except in fight or flight. 
      

   
   

• The Autonomic Nervous system: (we cover EEGs and Sleep)
  
  • Reticular Activating System (RAS): 
    

1. Reticular Formation is comprised of sensory afferents bound for the cerebrum going up to the brain stem (medulla, pons, and midbrain). 
   
2. The sensory afferents are going to have clusters of nuclei in white matter:
   
   1. As they go through the brain stem the more mid-line nuclei are called Raphe Nuclei.  
      
   2. Farther from the midline, but closer than the lateral line we have a medial group called a Large cell group. 
      
   3. Farther out from that we have a lateral group called a Small cell group. 
      
   4. The neurons of virtually all the senses send neurons to this area. (Such as from the eye or ear, they are above and go directly to the brain and talk to it).  They send messages into the reticular formation down into the brain stem.
      
3. The Reticular formation is an integral part of the RAS, but it is only one single part of the RAS system
   
4. The RAS sends a continual stream of impulses to the brain
   
   1. The messages change but the flow is continuous
      
5. It keeps the brain alert or puts the brain to sleep
   
6. The RAS system filters out what it considers unnecessary information. 
   
   1. You don't feel something if you are not paying attention to it.  (ex. Can you feel your socks?)
      
7. The RAS has the cerebral cortex disregarding 99% of the sensory stimuli that are sent to the brain. If we did not have this filter, the brain could not handle all the messages. 
   
   1. The filtering of the RAS system is shut down by LSD, and then you can feel more of the sensory stimuli. 
      
   2. Bad trips – take LSD and something scares you and you stay scared (LSD stops itself)
      
   3. You don't have flash backs, but there is only a sense of flashbacks
      
      

 
 

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