Environmental dependent influences on the developmental refinement of excitatory inputs at an ultra-fast coincidence detector neuron
Molecular Biology and Physiology of Neurons and Glial Cells
Final Report Abstract
In the successful proposal “Environmental dependent influences on the developmental refinement of excitatory inputs at an ultra-fast coincidence detector neuron” the Felmy lab was able to determine the environmental drive for the developmental refinement of excitation onto the ultra-fast coincidence detector neurons in the medial superior olive (MSO). To alter the auditory environment for developing gerbils we raised them in a “noise box”. In this sound attenuated chamber, gerbils are challenged with broadband noise of moderate intensity during postnatal development. The presence of such omnidirectionally applied sounds are thought to increase the activity of auditory neurons and to suppress the available information about specific sound sources and thereby reducing the experience of sound source localization. Our in vitro data shows that the excitatory inputs to MSO neurons are slightly faster refined when gerbils are noise box reared. Thus, the loss of experience seems not to delay the refinement, as has been shown for inhibitory inputs, rather it is suggested that increased activity accelerates development of excitatory transmission in the MSO. We also show that MSO neurons unexpectedly show now action potential induced calcium transient in soma or dendrites when they are mature, as likely most other neurons do. Thus, postsynaptic activity does not lead to the standard calcium signal in these neurons. The major source of activity-dependent calcium entry to MSO neurons appear the excitatory synapses. In a side project, we were able to demonstrate that the relevant temporal precision of inputs to the MSO is adapted in a species-specific manner. Neurons that project onto MSO neurons are temporally more precise and fire more reliable in bats compared to gerbils. Thus, environmental sounds and the specific hearing adaptations alter the synaptic and cellular properties of auditory brainstem neurons and in particularly neurons of the ultra-fast coincidence detector systems required for sound source localization.
Publications
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Activity-Dependent Calcium Signaling in Neurons of the Medial Superior Olive during Late Postnatal Development. The Journal of Neuroscience, 40(8), 1689-1700.
Franzen, Delwen L.; Gleiss, Sarah A.; Kellner, Christian J.; Kladisios, Nikolaos & Felmy, Felix
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Ambient noise exposure induces long-term adaptations in adult brainstem neurons. Scientific Reports, 11(1).
Siveke, Ida; Myoga, Mike H.; Grothe, Benedikt & Felmy, Felix
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Structural arrangement of auditory brainstem nuclei in the bats Phyllostomus discolor and Carollia perspicillata. Journal of Comparative Neurology, 530(15), 2762-2781.
Pätz, Christina; Console‐Meyer, Laura & Felmy, Felix
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Species-Specific Adaptation for Ongoing High-Frequency Action Potential Generation in MNTB Neurons. The Journal of Neuroscience, 43(15), 2714-2729.
Kladisios, Nikolaos; Wicke, Kathrin D.; Pätz-Warncke, Christina & Felmy, Felix
