FIG. 3.
Simplified model of the interaction of afferent and efferent pathways involved in the prepulse inhibition, tactile blink reflex (BR) and auditory startle reflex (ASR) in humans. Red broken lines: Prepulses originated in the peripheral nerves (p-pns) and in the auditory system (p-ans); green lines: circuit for the electrically elicited BR; blue lines: circuit for the ASR. Black dotted line: inhibitory action exerted by the pedunculopontine nucleus (PPN) on the trigeminal nucleus (V). Yellow dotted and broken line: inhibitory action exerted by the PPN on the nucleus reticularis pontis caudalis. VII: Brainstem nucleus of the facial nerve; VIII: brainstem nucleus of the auditory nerve. SR: startle reflex, which is abnormal (asterisk) in restless legs syndrome.