Synaptic properties of the mammillary and cortical afferents to the anterodorsal thalamic nucleus in the mouse.
Input to sensory thalamic nuclei can be classified as either driver or modulator, based on whether or not the information conveyed determines basic postsynaptic receptive field properties. Here we demonstrate that this distinction can also be applied to inputs received by nonsensory thalamic areas. Using flavoprotein autofluorescence imaging, we developed two slice preparations that contain the afferents to the anterodorsal thalamic nucleus (AD) from the lateral mammillary body and the cortical afferents arriving through the internal capsule, respectively. We examined the synaptic properties of these inputs and found that the mammillothalamic pathway exhibits paired-pulse depression, lack of a metabotropic glutamate component, and an all-or-none response pattern, which are all signatures of a driver pathway. On the other hand, the cortical input exhibits graded paired-pulse facilitation and the capacity to activate metabotropic glutamatergic responses, all features of a modulatory pathway. Our results extend the notion of driving and modulating inputs to the AD, indicating that it is a first-order relay nucleus and suggesting that these criteria may be general to the whole of thalamus.
Petrof
Iraklis
I
Department of Neurobiology, University of Chicago, Chicago, Illinois 60637, USA.
Sherman
S Murray
SM
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D020643:Anterior Thalamic Nuclei / Q000166:cytology*; D002540:Cerebral Cortex / Q000502:physiology*; D004148:Dioxolanes / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D044927:Electron-Transferring Flavoproteins / Q000378:metabolism; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D010721:Phosphinic Acids / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D011724:Pyridazines / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D004148:Dioxolanes; D044927:Electron-Transferring Flavoproteins; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D010721:Phosphinic Acids; D011687:Purines; D011724:Pyridazines; C086109:3-aminopropyl-cyclohexylmethylphosphinic acid; C104068:4-(2-amino-6-chloro-9H-purin-9-yl)-1,3-dioxolane-2-methanol; C049853:gabazine