title: Load Rate and Temperature Dependent Mechanical Properties of the Cortical Neuron and Its Pericellular Layer Measured by Atomic Force Microscopy.
abstract: When studying the mechanical properties of cells by an indentation technique, it is important to take into account the nontrivial pericellular interface (or pericellular "brush") which includes a pericellular coating and corrugation of the pericellular membrane (microvilli and microridges). Here we use atomic force microscopy (AFM) to study the mechanics of cortical neurons taking into account the presence of the above pericellular brush surrounding cell soma. We perform a systematic study of the mechanical properties of both the brush layer and the underlying neuron soma and demonstrate that the brush layer is likely responsible for the low elastic modulus (<1 kPa) typically reported for cortical neurons. When the contribution of the pericellular brush is excluded, the average elastic modulus of the cortical neuron soma is found to be 3-4 times larger than previously reported values measured under similar physiological conditions. We also demonstrate that the underlying soma behaves as a nonviscous elastic material over the indentation rates studied (1-10 μm/s). As a result, it seems that the brush layer is responsible for the previously reported viscoelastic response measured for the neuronal cell body as a whole, within these indentation rates. Due to of the similarities between the macroscopic brain mechanics and the effective modulus of the pericellular brush, we speculate that the pericellular brush layer might play an important role in defining the macroscopic mechanical properties of the brain.
authors.affiliation: Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Marc
authors.initials: M
authors.lastname: Simon
authors.affiliation: Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Maxim
authors.initials: M
authors.lastname: Dokukin
authors.affiliation: Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Vivekanand
authors.initials: V
authors.lastname: Kalaparthi
authors.affiliation: Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Elise
authors.initials: E
authors.lastname: Spedden
authors.affiliation: Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Igor
authors.initials: I
authors.lastname: Sokolov
authors.affiliation: Department of Physics and Astronomy, ‡Center for Nanoscopic Physics, §Department of Mechanical Engineering, and ∥Department of Biomedical Engineering, Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Cristian
authors.initials: C
authors.lastname: Staii
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D002540:Cerebral Cortex / Q000166:cytology; D055119:Elastic Modulus; D019276:Glycocalyx / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D008871:Microvilli / Q000502:physiology* / Q000648:ultrastructure; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D013696:Temperature