Abstract
Despite its critical importance in experimental and clinical neuroscience, at present there is no systematic method to predict which neural elements will be activated by a given stimulation regime. Here we develop a novel approach to model the effect of cortical stimulation on spiking probability of neurons in a volume of tissue, by applying an analytical estimate of stimulation-induced activation of different cell types across cortical layers. We utilize the morphology and properties of axonal arborization profiles obtained from publicly available anatomical reconstructions of the twelve main categories of neocortical neurons to derive the dependence of activation probability on cell type, layer and distance from the source. We then propagate this activity through the local network incorporating connectivity, synaptic and cellular properties. Our work predicts that (a) intracranial cortical stimulation induces selective activation across cell types and layers; (b) superficial anodal stimulation is more effective than cathodal at cell activation; (c) cortical surface stimulation focally activates layer I axons, and (d) there is an optimal stimulation intensity capable of eliciting cell activation lasting beyond the end of stimulation. We conclude that selective effects of cortical electrical stimulation across cell types and cortical layers are largely driven by their different axonal arborization and myelination profiles.
Highlights
Brain stimulation is widely used to probe the properties of neural systems [1,2,3,4], to normalize dysfunction, or to manipulate brain activity, including enhancing memories and learning [10,11,12,13]
Since different neuron types are distributed differently across cortical layers [30], it is legitimate to expect that their different properties and placement in the cortex would affect if and how these neurons respond to surface electrical stimulation
Averaged axonal density represents overall morphological properties of a given type of neurons and gives the general intuition on how the anatomy of a given cell type can influence how it is affected by electrical stimulation
Summary
Brain stimulation is widely used to probe the properties of neural systems [1,2,3,4], to normalize dysfunction (e.g., deep brain stimulation for Parkinsonian symptoms [5,6,7] and epileptic patients [8], Direct-Current Stimulation for stroke patients [9]), or to manipulate brain activity, including enhancing memories and learning [10,11,12,13]. The secondary effects of the directly activated neurons on other cells may be more distributed and prolonged than the direct effects themselves [15]. Depending on the goal of stimulation, the effect of interest could be driving cells to spike or inducing sub-threshold changes. It has been difficult to infer these observations by applying the physics of current fields to cortical anatomy and physiology
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
