Pathway and directional specificity of Hebbian plasticity in the cortical visual motion processing network
Michele Bevilacqua,
Krystel R. Huxlin,
Friedhelm C. Hummel,
Estelle Raffin
Affiliations
Michele Bevilacqua
Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, EPFL, Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland
Krystel R. Huxlin
The Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, USA
Friedhelm C. Hummel
Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, EPFL, Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland; Clinical Neuroscience, University of Geneva Medical School, Geneva, Switzerland
Estelle Raffin
Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, EPFL, Geneva, Switzerland; Defitech Chair in Clinical Neuroengineering, Neuro-X Institute (NRX) and Brain Mind Institute, Clinique Romande de Readaptation (CRR), EPFL Valais, Sion, Switzerland; Corresponding author
Summary: Cortico-cortical paired associative stimulation (ccPAS), which repeatedly pairs single-pulse transcranial magnetic stimulation (TMS) over two distant brain regions, is thought to modulate synaptic plasticity. We explored its spatial selectivity (pathway and direction specificity) and its nature (oscillatory signature and perceptual consequences) when applied along the ascending (Forward) and descending (Backward) motion discrimination pathway. We found unspecific connectivity increases in bottom-up inputs in the low gamma band, probably reflecting visual task exposure. A clear distinction in information transfer occurred in the re-entrant alpha signals, which were only modulated by Backward-ccPAS, and predictive of visual improvements in healthy participants. These results suggest a causal involvement of the re-entrant MT-to-V1 low-frequency inputs in motion discrimination and integration in healthy participants. Modulating re-entrant input activity could provide single-subject prediction scenarios for visual recovery. Visual recovery might indeed partly rely on these residual inputs projecting to spared V1 neurons.
