Short Communication Volume 2 Issue 5 - March 2017 DOI: 10.19080/OAJNN.2017.02.555600 Open Access J Neurol Neurosurg Copyright © All rights are reserved by Kimberle M Jacobs Neurophysiological Study of Traumatic Brain Injury: To Slice or Not to Slice Jianli Sun and Kimberle M Jacobs* Department of Anatomy & Neurobiology, Virginia Commonwealth University, USA Submission: March 04, 2017; Published: March 20, 2017 *Corresponding author: Kimberle M Jacobs, PhD Associate Professor, Department of Anatomy & Neurobiology Virginia Commonwealth University, PO Box 980709 Richmond, VA 23298, USA, Tel: ; Fax: ; Email: Introduction One of the most critical neuropathological features of traumatic brain injury (TBI) is axotomy [1-5]. Even in mild (m) TBI, diffuse axotomy is easily and consistently observed as axons that end in swellings and dislocation from the distal part of the axon [6-8]. Integrity of axons can be measured in the clinical population with diffusion tensor imaging (DTI) [9-12]. Patient outcome has been correlated with DTI results, [13-16] although subacute imaging may be most effective in this regard [17,18]. Correlations may also be stronger for severe and moderate as opposed to mild injuries [19]. DTI results have also been shown to correlate with the degree of diffuse axonal injury (DAI) as measured with amyloid precursor protein (APP) staining that accumulates in the axonal swelling [20,21]. Treatment assessments have typically been focused on reduction of this axonal injury [22-29], although it has also been recognized that some measures of DAI improve over time while cognitive dysfunction persists [30]. Because axotomy also occurs during preparation of ex vivo brain slices, it could be argued that this methodology should not be used for study of mechanisms associated with TBI. Vibratome-axotomized neurons can certainly be identified at the surface of acute slices (Figure 1A & 1B). This is one reason most investigators performing recordings in slices choose neurons that are at least one cell layer deep to surface neurons, and typically 40-60 m into the tissue. Creation of ex vivo slices for study of normal physiological function has been a staple of neuroscience research for decades [31,32]. The benefits of stability, visualized access to specific cell types and placement of electrodes, as well as feasibility of drug application have been previously described [33-35]. However, the idea that slicing produces pathology has also been used to create a model of post-traumatic epilepsy utilizing organotypic hippocampal slices that survive for weeks [36-40]. In this model, interictal- like epileptiform activity is first observed after 14 days in vitro, while ictal-like activity is seen by 21 days [38]. The fact that this abnormal activity develops in days and not hours suggests that it may be due to synaptic reorganization that is secondary to the axotomy and thus unlikely to play a role in the physiology of acute slices. We recently chose to use the acute slice to study physiological effects of trauma, specifically in order to target the axotomized neurons which are in the minority and located diffusely within Open Access J Neurol Neurosurg 2(5): OAJNN.MS.ID.555600 (2017) 001 Abstract Diffuse axotomy is characteristic of mild traumatic brain injury (TBI) both clinically and in experimental models. Axotomy also occurs during preparation of acute brain slices for physiological recordings. Brain slices have been used for decades and have many advantages, including the ability to select cells within particular locations or with specific morphologies for study. The question addressed here is whether creating additional axotomy by preparing brain slices introduces additional injury that is already typical of TBI. We have previously demonstrated alterations in both intrinsic membrane and synaptic properties recorded in brain slices after mTBI. Here we examined whether axotomized neurons differ from intact neurons in slices made from naïve mouse pups. There was no significant difference in either excitatory synaptic postsynaptic currents or in any measures of intrinsic membrane and cellular properties. These results suggest that creating the brain slices does not induce alterations similar to that observed within two days of mTBI induced by fluid percussion injury. Thus ex vivo slices are an appropriate methodology to study the effects of TBI. Keywords: Ex vivo slice; Electrophysiology; Axotomy; EPSC; Membrane properties; Neurotrauma Abbreviations: AHP: After Hyperpolarization; APP: Amyloid Precursor Protein; DAI: Diffuse Axonal Injury; DAP: Depolarizing After Potential; DTI: Diffusion Tensor Imaging; TBI: Traumatic Brain Injury