Lectures3+4-Chapter_2-BiologicalFoundations

55 each neuron acts like a miniature processor that

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Unformatted text preview: mitter onto the dendrites of the next neuron in the network. 55 Each Neuron Acts Like a Miniature Processor That Surveys Incoming Signals and Computes Whether it Will Send An Outgoing Signal If threshold is reached at the axon burda kaldin burdan hillock, then action potentials will be sonrasina bakman lazim generated and transmitter will be released on the postsynaptic neuron. derste devam ettiler This decision is made at each interface with a new neuron (synapse) Via such circuits, sensory signals ultimately propagate to higher regions of the brain 56 General principles of sensory coding - 1 Coding of stimulus location: Topographic relationships are maintained from the sensory organ to regions of the brain via topographically-organized patterns of axon connections. Location coding is not done in this way for sounds, and location information is not preserved in taste/smell Receptive field: Area on a sensory surface that will influence the activity of a neuron. 57 General principles of sensory coding - 2 58 Intensity coding: Humans can perceive differences in stimulus intensity, yet the action potential is fixed in size and duration. How might intensity coding happen? Adrian (1928) found that for more intense stimuli, frequency of action potentials increases…. However, this relationship does not entirely account for the relationship between stimulus magnitude and perceived magnitude, suggesting that other information is integrated along with the sensory input to arrive at the percept. Edgar Adrian (1889-1977) General principles of sensory coding - 3 Duration coding: Sensory adaptation occurs when the continued application of a stimulus makes us less aware of its presence: This is thought to occur due to an inactivation of ion channels that cannot become “reset” again until neural activity decreases; the “inactive” ion channels mean that it is harder for a neuron to fire an action potential, resulting in fewer action potentials. There are also some receptors that do not appear to “inactivate” or do s...
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