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