Physiology 3120 Lecture Notes - Evoked Potential, Axon Hillock, Somatotopic Arrangement

• School: Western University
• Department: Physiology
• Course: Physiology 3120
• Professor: Tom Stavraky

Document Summary

Consciousness, evoked potential, eeg, and sleep: two components of consciousness. Content of consciousness; cerebral cortex functions (memory, perception, etc. ) Level of consciousness; reticular system in the brainstem: evoked potentials. Primary & secondary (only worry about primary) Only observed in the leg area of the somatosensory cortex; activation of different populations of neurons will produce different patterns. Change in voltage; results from summation of extracellular currents associated with post- synaptic potentials; not local currents associated with aps (see figure) Current from dcml axons doesn"t contribute to evoked potential. Aps originating at axon hillock contribute nothing to the evoked potential. Used to (i) determine integrity of reticular pathway, and (ii) elucidate somatotopic organization of cortex: electroencephalogram (eeg) Neurons fluctuating between epsps and ipsps at about 10 hz during one form of sleep. Interneurons in the thalamus inhibit themselves, so that when epsps occur, more inhibition occurs, and vice-versa. When subject is awake & alert, subject shows a desynchronized pattern.