We have proposed that general anesthetics, irrespective of their precise mechanism of action, induce loss of consciousness when they bring about the breakdown of information integration within the corticothalamic system. Here, we will test this proposal using animal models in which we can investigate the role of different neuronal populations in anesthetic unconsciousness. Specifically, it is unclear whether anesthetic loss/recovery of consciousness (LOC/ROC) relies on a thalamic switch or a direct action on cortical cells. Within cortex, it is not known whether anesthetic LOC/ROC is a global phenomenon or is due to specific neural populations and fiber pathways. We hypothesize that pyramidal cells in supragranular (SG) layers, which form a highly integrated network both within and across cortical areas, are ideally poised to support information integration and thereby consciousness. The roles of different thalamic populations in modulating cortical interactions are also unknown. We hypothesize that thalamic matrix cells, with their widespread cortical projections focused especially in SG layers, enable cortical information integration. In addition t actions on specific cell types, we propose that anesthetics target specific synaptic pathways, suppressing cortico-cortical (CC) and matrix thalamo-cortical (TC) synaptic connections, while leaving core TC connections intact. To test these hypotheses, we will take advantage of recent developments in laminar multiunit recordings in freely- moving rodents to examine the neural correlates of LOC/ROC, and recordings of network activity in brain slices to investigate the cellular and circuit mechanisms of these correlates. Moreover, we will use optogenetic and pharmacogenetic methods to transiently activate/inactivate specific cortical layers and thalamic populations and explore their causal involvement in LOC/ROC.

Public Health Relevance

How anesthetics produce unconsciousness remains mysterious, but both empirical and theoretical considerations indicate that consciousness requires a high level of information integration in specific brain regions. In this project we will test in mice the hypothesis that general anesthetics, irrespective of their precise mechanism of action, induce loss of consciousness when they bring about the breakdown of information integration in specific neuronal populations within the corticothalamic system.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM116916-02
Application #
9252491
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Cole, Alison E
Project Start
2016-04-01
Project End
2020-03-31
Budget Start
2017-04-01
Budget End
2018-03-31
Support Year
2
Fiscal Year
2017
Total Cost
$403,066
Indirect Cost
$135,718
Name
University of Wisconsin Madison
Department
Psychiatry
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Honjoh, Sakiko; Sasai, Shuntaro; Schiereck, Shannon S et al. (2018) Regulation of cortical activity and arousal by the matrix cells of the ventromedial thalamic nucleus. Nat Commun 9:2100
Miller, Andrew H; Howe, Hollis B; Krause, Bryan M et al. (2018) Pregnancy-Associated Plasma Protein-aa Regulates Photoreceptor Synaptic Development to Mediate Visually Guided Behavior. J Neurosci 38:5220-5236
Chang, Jui-Yang; Fecchio, Matteo; Pigorini, Andrea et al. (2018) Assessing recurrent interactions in cortical networks: Modeling EEG response to transcranial magnetic stimulation. J Neurosci Methods 312:93-104
Hentschke, H; Raz, A; Krause, B M et al. (2017) Disruption of cortical network activity by the general anaesthetic isoflurane. Br J Anaesth 119:685-696
Nir, Yuval; Andrillon, Thomas; Marmelshtein, Amit et al. (2017) Selective neuronal lapses precede human cognitive lapses following sleep deprivation. Nat Med 23:1474-1480
Funk, Chadd M; Peelman, Kayla; Bellesi, Michele et al. (2017) Role of Somatostatin-Positive Cortical Interneurons in the Generation of Sleep Slow Waves. J Neurosci 37:9132-9148