2 18 15 Lecture 16 Sensory Receptors Figure 7 1 Two designs o 1 Directly by neuron end o 2 Receptor cell to neuron end o Speed difference o If slow what s the benefit Types are specific o Mechanoreceptors pressure or stretch o Thermoreceptors Temperature o Photoreceptors light wave aka photons o Chemoreceptors chemicals o Nociceptor painful stimuli e x heat or tissue damage Coding intensity location sensory transduction o Figure 7 2 o Intensity The two key parts for coding are how intense the stimulus is ex is the stove warm or hot and location ex did I burn my hand or my arm Sensory transduction Variable stimulus stimuli Variable receptor potentials GPs Something can be cool warm or hot small medium large Our receptor turns that stimulus into an electrical signal called a receptor potential aka graded potential Variable action potential pattern not magnitude Variable neurotransmitter amount More action potentials more neurotransmitters being released o Larger stimulus higher action potential frequency increase in number of neurotransmitters o Location figure 7 4 1 Receptive field area covered Size related to localizing narrow more specific Figure 7 6 Smaller receptor is better for localization ability bigger receptor worse localization inverse relationship Density related to sensitivity o Figure with 2 pronged pins One has both prongs touch one receptor The other has each prong touching a different receptor 2 18 15 Overlap possible get recruitment o Figure 7 8 o Venn diagram o The overlap helps identify where the stimulus is coming from 2 Lateral Inhibition Sharpens the pattern contrast Figure 7 9 Crossing over ALL are inhibited Processing Figure 7 14 Ascending pathway in CNS o Brain stem thalamus cerebrum with cross o Ex left hand to right hemisphere To specific brain regions o Ex visual auditory taste Input can be impacted by output o Figure 7 11
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