The present invention relates to apparatuses for stimulating in vivo light-sensitive cells of an area comprising at least a light source having a wavelength adapted to stimulate the light-sensitive cells.They can be used on muscles or organs requiring an excitation and inhibition like heart suffering cardiomyopathy.Such apparatuses provide a homogeneous stimulation of the light-sensitive cells of an area that can be larger than the area covered by a traditional electrode.
