1 Activation of the same mGluR5 receptors in the amygdala causes divergent effects 2 on specific versus indiscriminate fear 3 4 Mohammed Mostafizur Rahman1,2,#, Sonal Kedia1,#, Giselle Fernandes1#, Sumantra 5 Chattarji1,2,3* 6 7 1National Centre for Biological Sciences, Tata Institute of Fundamental Research, 8 Bangalore 560065, India 9 10 2Centre for Brain Development and Repair, Institute for Stem Cell Biology and 11 Regenerative Medicine, Bangalore 560065, India 12 13 3Centre for Integrative Physiology, Deanery of Biomedical Sciences, University of 14 Edinburgh, Hugh Robson Building, George Square, Edinburgh EH89XD, UK 15 16 17 * Corresponding Author: Prof. Sumantra Chattarji 18 Centre for Brain Development and Repair, Institute for 19 Stem Cell Biology and Regenerative Medicine and 20 National Centre for Biological Sciences 21 Bangalore 560065, INDIA 22 E-Mail:
[email protected] 23 # Equal contribution 24 1 25 Abstract 26 27 Although mGluR5-antagonists prevent fear and anxiety, little is known about how the 28 same receptor in the amygdala gives rise to both. Combining in vitro and in vivo 29 activation of mGluR5 in rats, we identify specific changes in intrinsic excitability and 30 synaptic plasticity in basolateral amygdala neurons that give rise to temporally distinct 31 and mutually exclusive effects on fear-related behaviors. The immediate impact of 32 mGluR5 activation is to produce anxiety manifested as indiscriminate fear of both tone 33 and context. Surprisingly, this state does not interfere with the proper encoding of tone- 34 shock associations that eventually lead to enhanced cue-specific fear. These results 35 provide a new framework for dissecting the functional impact of amygdalar mGluR- 36 plasticity on fear versus anxiety in health and disease.