Altered evoked low-frequency connectivity from SI to ACC following nerve injury in rats

Lea Tøttrup; S Farokh Atashzar; Dario Farina; Ernest Nlandu Kamavuako; Winnie Jensen

doi:10.1088/1741-2552/abfeb9

Altered evoked low-frequency connectivity from SI to ACC following nerve injury in rats

J Neural Eng. 2021 May 24;18(4). doi: 10.1088/1741-2552/abfeb9.

Authors

Lea Tøttrup¹, S Farokh Atashzar^{2

3}, Dario Farina⁴, Ernest Nlandu Kamavuako^{5

6}, Winnie Jensen¹

Affiliations

¹ Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
² Departments of Electrical and Computer Engineering, and Mechanical and Aerospace Engineering, New York University, New York, NY, USA.
³ NYU WIRELESS center, New York University (NYU), New York, NY, USA.
⁴ Department of Bioengineering, Imperial College London, London, United Kingdom.
⁵ Department of Engineering, King's College London, London, United Kingdom.
⁶ Université de Kindu, Faculté de Médecine, Département des Sciences de base, Maniema, DR Congo.

PMID: 33957613
DOI: 10.1088/1741-2552/abfeb9

Abstract

Objective. Despite decades of research on central processing of pain, there are still several unanswered questions, in particular regarding the brain regions that may contribute to this alerting sensation. Since it is generally accepted that more than one cortical area is responsible for pain processing, there is an increasing focus on the interaction between areas known to be involved.Approach. In this study, we aimed to investigate the bidirectional information flow from the primary somatosensory cortex (SI) to the anterior cingulate cortex (ACC) in an animal model of neuropathic pain.19 rats (nine controls and ten intervention) had an intracortical electrode implanted with six pins in SI and six pins in ACC, and a cuff stimulation electrode around the sciatic nerve. The intervention rats were subjected to the spared nerve injury (SNI) after baseline recordings. Electrical stimulation at three intensities of both noxious and non-noxious stimulation was used to record electrically evoked cortical potentials. To investigate information flow, two connectivity measures were used: phase lag index (PLI) and granger prediction (GP). The rats were anesthetized during the entire study.Main results. Immediately after the intervention (<5 min after intervention), the high frequency (γandγ+) PLI was significantly decreased compared to controls. In the last recording cycle (3-4 h after intervention), the GP increased consistently in the intervention group. Peripheral nerve injury, as a model of neuropathic pain, resulted in an immediate decrease in information flow between SI and ACC, possibly due to decreased sensory input from the injured nerve. Hours after injury, the connectivity between SI and ACC increased, likely indicating hypersensitivity of this pathway.Significance. We have shown that both a directed and non-directed connectivity between SI and ACC approach can be used to show the acute changes resulting from the SNI model.

Keywords: animal model of pain; functional connectivity analysis; granger prediction; spared nerve injury.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Gyrus Cinguli
Neuralgia*
Peripheral Nerve Injuries*
Rats
Sciatic Nerve
Somatosensory Cortex