Quantification of prefrontal cortical neuronal ensembles following conditioned fear learning in a Fos-LacZ transgenic rat with photoacoustic imaging in Vivo

James I Matchynski; Timothy S Cilley; Nareen Sadik; Kassem M Makki; Min Wu; Rayyan Manwar; Alexander R Woznicki; Srinivasu Kallakuri; Cynthia L Arfken; Bruce T Hope; Kamran Avanaki; Alana C Conti; Shane A Perrine

doi:10.1016/j.pacs.2023.100551

Quantification of prefrontal cortical neuronal ensembles following conditioned fear learning in a Fos-LacZ transgenic rat with photoacoustic imaging in Vivo

Photoacoustics. 2023 Aug 27:33:100551. doi: 10.1016/j.pacs.2023.100551. eCollection 2023 Oct.

Authors

James I Matchynski^{1

2

3

4}, Timothy S Cilley¹, Nareen Sadik¹, Kassem M Makki³, Min Wu³, Rayyan Manwar⁵, Alexander R Woznicki³, Srinivasu Kallakuri¹, Cynthia L Arfken^{1

2}, Bruce T Hope⁶, Kamran Avanaki⁵, Alana C Conti^{1

2

3}, Shane A Perrine^{1

2}

Affiliations

¹ Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI, USA.
² Translational Neuroscience Program, Wayne State University School of Medicine, Detroit, MI, USA.
³ John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA.
⁴ Wayne State MD/PhD Program, Wayne State University School of Medicine, Detroit, MI, USA.
⁵ University of Illinois at Chicago, Department of Bioengineering, Chicago, IL, USA.
⁶ The National Institute on Drug Abuse (NIDA), Intramural Research Program, Baltimore, MD, USA.

Abstract

Understanding the neurobiology of complex behaviors requires measurement of activity in the discrete population of active neurons, neuronal ensembles, which control the behavior. Conventional neuroimaging techniques ineffectively measure neuronal ensemble activity in the brain in vivo because they assess the average regional neuronal activity instead of the specific activity of the neuronal ensemble that mediates the behavior. Our functional molecular photoacoustic tomography (FM-PAT) system allows direct imaging of Fos-dependent neuronal ensemble activation in Fos-LacZ transgenic rats in vivo. We tested four experimental conditions and found increased FM-PAT signal in prefrontal cortical areas in rats undergoing conditioned fear or novel context exposure. A parallel immunofluorescence ex vivo study of Fos expression found similar findings. These findings demonstrate the ability of FM-PAT to measure Fos-expressing neuronal ensembles directly in vivo and support a mechanistic role for the prefrontal cortex in higher-order processing of response to specific stimuli or environmental cues.

Keywords: Fear-conditioning; Fos-LacZ transgenic rat; Functional imaging; Medial prefrontal cortex; Molecular imaging; Neuronal ensembles; Optoacoustic imaging; Photoacoustic imaging.