Eye and eyelid movements during blinking: an eye blink centre?

This chapter focuses on the eye and eyelid movements during blinking and discusses the electromyographical (EMG) features of the orbicularis oculi (OO) and levator palpebrae (LP) muscles during spontaneous as well as reflexly activated blinks in healthy and patient subjects. A blink is a complex action of eyelid and eyeball muscles. To obtain more insight into mechanisms underlying the coordination of eyelid closing and opening and eyeball muscles during blinking, the chapter examines simultaneously displayed movements of the eye and eyelid along with the EMG and reflex features of the OO muscle. Additionally, the chapter investigates the EMG and reflex features of simultaneously recorded OO and LP activities both in healthy subjects and in patients with localized brainstem lesions. From the discussion of stereotyped associated eye and eyelid movements during blinking, the chapter proposes that the concurrent activation of extraocular muscles and of the eyelid opening and closing muscles during blinking has a common origin: an eye blink generator. Similar to the saccadic pulse generator, this distinct eye blink generator may be composed of different premotor structures located in the brainstem including “omnipause neurons” that may stop saccades during blinking or may suppress blinking during a saccadic eye movement.