Laterality of auditory startle responses in humans

• Published in: Clinical neurophysiology Vol. 119; no. 2; pp. 309 - 314
• Main Authors: Kofler, Markus, Müller, Jörg, Rinnerthaler-Weichbold, Martina, Valls-Solé, Josep
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.02.2008; Elsevier Science
• Subjects: Acoustic Stimulation - methods; Adult; Aged; Area Under Curve; Auditory startle response; Biological and medical sciences; Brainstem reflex; Dose-Response Relationship, Radiation; Electrodiagnosis. Electric activity recording; Electromyography; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Human; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Muscle, Skeletal - innervation; Nervous system; Neurology; Normative values; Reaction Time; Reflex, Startle - physiology; Side-to-side difference; Vertebrates: nervous system and sense organs; Auditory startle response; Human; Normative values; Brainstem reflex; Side-to-side difference; Reflex; Probability; Orbicularis oculi muscle; Hand; Electrodiagnosis; Handedness; Biceps brachii muscle; Sternocleidomastoid muscle
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2007.11.006

To examine whether the auditory startle reaction in humans is a symmetrical or asymmetrical bilateral brainstem reflex in response to an unexpected loud stimulus. We investigated physiological side-to-side differences of auditory startle responses (ASRs) in 28 healthy adult subjects. ASRs were elicited by randomly presented auditory stimuli. Reflex electromyographic activity was simultaneously recorded from masseter, orbicularis oculi, sternocleidomastoid and biceps brachii muscles bilaterally. ASR area-under-the-curve was significantly larger on the side contralateral to hand dominance in sternocleidomastoid, and tended to be larger on the dominant side in biceps brachii. In contrast, in orbicularis oculi, ASR area was significantly larger on the right vs. left side, irrespective of handedness. There was no significant side-to-side difference of ASR probability and ASR latency in any muscle. The present data expand our knowledge on physiological variables influencing ASRs and provide evidence of laterality of ASRs in sternocleidomastoid and biceps brachii, being associated with hand dominance, and in orbicularis oculi, irrespective of handedness. Normal limits of side-to-side differences offer an additional parameter to be taken into account in studies of patients presenting with asymmetric symptoms.