Cell-type specific arousal dependent modulation of spontaneous thalamic activity in the lateral geniculate nucleus
Benedek Molnár1, Péter Sere1, Sándor Bordé2, Krisztián Koós3, Péter Horváth3, 4 and Magor L. Lőrincz1, 2
1 Department of Physiology, Faculty of Medicine, University of Szeged, Szeged, Hungary 2Department of Physiology, Anatomy and Neuroscience, Faculty of Sciences University of Szeged, Szeged, Hungary; 3Biological Research Centre of the Hungarian Academy of Sciences, 62Temesvári krt, H-6726, Szeged, Hungary; 4Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland.
Keywords: brain state, inhibition, cortical feedback, lateral geniculate nucleus, thalamocortical, interneuron. State dependent thalamocortical activity is important to sensory coding, oscillations and cognition. The lateral geniculate nucleus relays visual information to the cortex, but the state dependent spontaneous and visually evoked activity of LGN neurons in awake behaving animals remains controversial. Using a combination of pupillometry, extracellular and intracellular recordings from identified LGN neurons we show that thalamocortical neurons and interneurons are inversely related to arousal forming two complementary coalitions. Intracellular recordings indicated that the membrane potential of LGN TC neurons was tightly correlated to fluctuations in pupil size. Inactivating either the brainstem cholinergic nuclei or local thalamic blockade of muscarinic acetylcholine receptors suppressed the arousal dependency of both TC neurons and LGN interneurons via different mechanisms. Taken together our results show that LGN neuronal membrane potential and action potential output are dynamically linked to arousal dependent brain states in awake mice and this fact might have important functional implications.