MT2 notes

MT2 notes - 1 Lecture 6 Mechanisms of imprinting Filial...

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1 Lecture 6 Mechanisms of imprinting Filial imprinting in geese - Formation of social attraction to a specific individual - The eventual recognition of a suitable mate - Linked to a sensitive period of development - We don’t know the mechanism o Has been approached using “lesion studies” o Hyperstriatum ventral (IMHV) is involved o Synpatic changes are implicated and are stimulus dependent i.e. different stimuli produce different changes o Involves complex stimuli (visual, auditory, etc) - Other examples (more than one neural mechanism is involved) o Homestream imprinting in salmon o Imprinting to prey odors o Imprinting to the scent of mom (rabbits, mice, rats, etc) o Imprinting to the scent of baby (sheep) o Pregnancy block in mice o Kin recognition / mate selection Olfactory imprinting in salmon - Homestream imprinting in salmon o Hyp: the peripheral olfactory system is tuned to the scent of the home stream (1 st question level of analysis) Imprinting occurs during the parr-smolt period Changes in plasma T 4 during smolting Organizational hormone for this memory o Salmon imprint to the scent of the home stream during a critical period of development They later use this odor memory to guide them home How does this happen? HYP: Imprinting occurs during the parr-smolt transformation (PST) o How does this develop? HYP: Olfactory imprinting involves a timing of the peripheral olfactory system to the home stream during PST Result: Yes o Olfactory system overview Olfactory rosette water comes in through nose to olfactory epithelium cells with very long axons o Whole cell patch-clamp recording Isolated olfactory receptor neuron -> gigaohm seal -> whole-cell recording
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2 o Results PEA more cell responding to PEA in the imprinted fish L-serine (mammalian hair) more cells responding to the nonimprinting Testing of sensitivity to cells to any odor or just to PEA? It’s not to any odor but to the one they were exposed to early in life - How does this develop o Hyp b: the PST is associated with a proliferation of receptor neurons in the peripheral olfactory epithelium Result: Yes o Does smolting induce proliferation? Methods: Inject BrDU, prefuse fish and do immunocytochemistry Count cells in serial sections o Yes there is proliferation of cells during this time, growth in epithelium o Hyp C: proliferation can be induced with thyroid hormone Result is yes Does T3 induce proliferation? T3 implanted in parr/placebo fish implant cholesterol pellet Methods the same as above o New model for olfactory imprinting Maturation hormones up-regulate receptors sensitive to imprinted odors thyroid hormone During imprinting, thyroid hormone promotes proliferation of olfactory receptor neurons that are sensitive to a wide variety of odors Olfactory receptor neurons that are most active survive while others
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MT2 notes - 1 Lecture 6 Mechanisms of imprinting Filial...

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