1. Awake Brain Surgery: http://www.youtube.com/watch?v=rqWBDHRvHrQ&feature=related

2. Transduction of Nerve Signals 1. Into the neuron 2. Through the neuron 3. From neuron to neuron

3. Transduction of Nerve Signals 1. Into the neuron  Two main ways for a signal to enter a nerve cell (neuron)  Mechanical stimulation – through physical contact of the receptor of the sensory neuron with an object (senses heat, cold, texture, pain)  Chemical binding- of neurotransmitter molecules to receptors on the dendrites of a neuron

4. Transduction of Nerve Signals  Chemical signal is carried from the dendrites, through the cell body to the axon  Action potential conducts the message along the length of the axon to the axon terminal  The key is the polarity of the axon membrane- determined by the concentration of Na+ and K+ ions along the inner and outer wall of axon membrane 2. Through the neuron

5. Transduction of Nerve Signals

6.  K + leak channels  leak K+ out of axon  Na + channels  pump Na+ into of axon  Na + / K + pumps  pump K+ back into axon and Na+ back out of axon 3 pumps control these concentrations

7. Action potential  Resting Potential  Membrane is polarized  Inside negative relative to outside  K+ leak channels open  Na+ channels and Na+ / K+ pumps are closed

8. Action potential  Resting Potential  Membrane is polarized  Inside negative relative to outside  K+ leak channels open  Na+ channels and Na+ / K+ pumps are closed  Action Potential  Membrane is depolarized  Outside negative relative to inside  Na+ channels open and K+ channels close  Na+ / K+ pumps are still closed

9. Action potential  Resting Potential  Membrane is polarized  Inside negative relative to outside  K+ leak channels open  Na+ channels and Na+ / K+ pumps are closed  Action Potential  Membrane is depolarized  Outside negative relative to inside  Na+ channels open and K+ channels close  Na+ / K+ pumps are still closed  Refractory Period  Membrane is repolarized  Inside negative relative to outside  Na+ channels close, Na+/K+ pumps open  K+ leak channels open at the end

10. Action potential http://highered.mcgraw-hill.com/olc/dl/120107/anim0013.swf http://www.blackwellpublishing.com/matthews/actionp.html

11. Transduction of Nerve Signals 1. Into the neuron 2. Through the neuron 3. From neuron to neuron

12. Transduction of Nerve Signals  3. From neuron to neuron  Transmission of the signal from one neuron to another happens at the synapse  In the axon terminal, neurotransmitters (such as acetylcholine) are released into the synaptic cleft, where the molecules migrate to the surface of the dendrites  The neurotransmitters bind to the receptors on the surface of the dendrite membrane, and send a chemical signal into the cell body which generates a new action potential

13. Transduction of Nerve Signals  3. From neuron to neuron http://highered.mcgraw-hill.com/olc/dl/120107/anim0015.swf http://www.blackwellpublishing.com/matthews/nmj.html

14.  http://delicategeniusblog.com/?p=552 http://delicategeniusblog.com/?p=552