BIOL 3800 1st Edition Lecture 14 Outline of Current Lecture I. Brodmann AreasA. Subsections and their FunctionsB. HomunculusII. The Autonomic Nervous SystemA. Sympathetic and ParasympatheticB. Synaptic Connections of the Autonomic Nervous SystemC. Opposing Effects on Target Tissue (Sympathetic and Parasympathetic)III. Supplemental ReadingA. Pathological Changes by Oliver SacksCurrent Lecture“Structural and Functional Organization of Nervous System”(Chapter 8 and 11 Part II)I. Brodmann AreasA. Subsections and their FunctionsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. If you slice through area 4 and then take a coronal section and look at it you willhave all sorts of subsections it will look like this:2. If you slice somewhere different it will look different a. For example: obviously if you slice through area 17 it will look different. 3. Another place to cut is along area 3 and area 4 depending on whether you are on top or coming around from the side wherever you are there are different functions and that’s what they call homunculusB. Homunculus1. This is a homunculus diagram it looks a little bit awkward.2. Dr. Gross put the picture you see underneath in order to avoid confusion because if you don’t look at this very carefully you say these things are side by side and say on the left side there is sensory and on the right side there is motor and these things don’t exist side by side. 3. Sensory is behind the central canal or the central sulcus or the fissure of Rolando and the motor area is in front of it but they put it side by side to save space.4. If we start with the motor area, area 4 sensations from your toes are interpreted inside your longitudinal fissure that is true for all people so you need to know that. 5. Then your knee right at the curvature then we get to more interesting things such as the hand and all the fingers. 6. The hand and the fingers all the way to the thumb take up an enormous amount of space on the cortex what does that tell you? a. The more delicate the movement you make with some of your muscles the morearea you need to control that.b. So the hand takes up quite a bit and if you look at it from a certain side the cortex is almost vertical when you look at it from the side that’s where you have the lips so the hands are a little bit above that. What Dr. Gross wants you to know is not where the little finger is and so on, but a general area of where hands and fingers are and lips in this figure. So don’t mixup the hand area with the face and the lips 7. The other thing of course you have is the knee and hip and trunk you need to know that they are all further up in the cortex take and that they take up very little area. Why is this?a. You don’t have much movement there you can wiggle your hips and that’s aboutit but you can do remarkable things with your hands; because, it takes more neurons to control those movements. 8. In summary, need to know where things are in Area 4. 9. Now we will go to Area 3 which is now behind the fissure of Rolando.a. So now we are looking at a slice though area 3 and we are just looking at one side of it. b. Now there is some Asymmetry. 10. If you start way down in the longitudinal fissure this is where sensations from the genitalia are formed. Apparently that’s where the feeling of orgasm who knows whatelse is interpreted. a. If you stimulate here they’ve had people with electrodes in there trying to stop epilepsy so it must feel pretty good. 11. If you go up it’s the same thing for sensation hip, leg and so on in a small area because you don’t have many sensory receptors inside your leg. 12. Notice the lips has a lot of sensory endings and then we go down to the tongue and pharynx so need to know where these are in area 3. 13. People have messed with the sacral nerves during special surgery and you can trigger all kinds of things down there too. 14. Note on Phantom pain. a. We have some idea that it takes several neurons to get up to the cortex so pain actually at the periphery you need one cell that’s in the dorsal root ganglion it’s a C fiber if its burning pain it actually synapses in the spinal cord kind of in the top of the gray area and another neuron takes over and that takes the axons all the way up to the thalamus. b. Therefore it takes several relay stations and you learn from experience that a sensation comes from some barrier and that’s it so if you activate cells along theway that are responsible for that area even if that may have been cut away let’s say you don’t have your hand anymore you can still feel pain from your hand. Why? i. Because some of those cells are active. c. All phantom sensation where someone who has lost an arm says this is horrible my arm is just sticking straight up and it hurts like heck it is the neurons along the way including the thalamus if they are activated that will give you that sensation in the cortex. 15. The cortex is more plastic than we thought and the original idea is that everything is fixed by the H8 came from the visual cortex and there is some truth to that even though that wasn’t old but in the sensory area if you cut off one finger than the other fingers will take over that area and you have enhanced sensation.16. To clarify above homunculus diagram again, this picture is a coronal section the only thing that is confusing is the artist has put a section from area 3 over on one side and area 4 on the other side so he has just cut the coronal section in half and put them side by side to save space and yet that one fact causes all kinds of confusion. 17. If you have complete area 3 than this would also be area 3 sensation and it would be pretty much symmetric but obviously as we know there is some asymmetry in thebrain especially along the cortex. II. The Autonomic Nervous SystemA. Sympathetic and Parasympathetic1. The Autonomic Nervous System: the Sympathetic and Parasympathetic is found here belowis a picture.2. Do not memorize this picture it is much easier to reason with fight or flight logic.3. The Sympathetic System which allows you to “fight” or run away essentially is a thoracic lumbar outflow. a. We don’t have the connection to the brain in there but we are just saying there are cells in the spinal cord which then either synapse in the sympathetic chain ganglion which is outside the spinal