title: Time-sensitive reorganization of the somatosensory cortex poststroke depends on interaction between Hebbian and homeoplasticity: a simulation study.
abstract: Together with Hebbian plasticity, homeoplasticity presumably plays a significant, yet unclear, role in recovery postlesion. Here, we undertake a simulation study addressing the role of homeoplasticity and rehabilitation timing poststroke. We first hypothesize that homeoplasticity is essential for recovery and second that rehabilitation training delivered too early, before homeoplasticity has compensated for activity disturbances postlesion, is less effective for recovery than training delivered after a delay. We developed a neural network model of the sensory cortex driven by muscle spindle inputs arising from a six-muscle arm. All synapses underwent Hebbian plasticity, while homeoplasticity adjusted cell excitability to maintain a desired firing distribution. After initial training, the network was lesioned, leading to areas of hyper- and hypoactivity due to the loss of lateral synaptic connections. The network was then retrained through rehabilitative arm movements. We found that network recovery was unsuccessful in the absence of homeoplasticity, as measured by reestablishment of lesion-affected inputs. We also found that a delay preceding rehabilitation led to faster network recovery during the rehabilitation training than no delay. Our simulation results thus suggest that homeoplastic restoration of prelesion activity patterns is essential to functional network recovery via Hebbian plasticity.
authors.affiliation: Neuroscience Graduate Program, University of Southern California, Los Angeles, California; abains05@gmail.com.
authors.forename: Amarpreet Singh
authors.initials: AS
authors.lastname: Bains
authors.affiliation: Neuroscience Graduate Program, University of Southern California, Los Angeles, California; Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California; and M2H Laboratory, Euromov, University of Montpellier I, Montpellier, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Schweighofer
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008959:Models, Neurological; D009470:Muscle Spindles / Q000502:physiology; D016571:Neural Networks, Computer; D009473:Neuronal Plasticity; D009474:Neurons / Q000502:physiology*; D020127:Recovery of Function; D013003:Somatosensory Cortex / Q000503:physiopathology*; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D013569:Synapses / Q000502:physiology
keywords: Hebbian plasticity; computational model; homeoplasticity; rehabilitation timing; stroke rehabilitation