Summation between acoustic and trigeminal stimuli evoking startle

Electrical stimulation of the spinal trigeminal pathway evokes a short-latency startle-like response in rats. To explore the relationship between acoustic and tactile systems mediating startle, we studied temporal summation between pairs of startle-evoking stimuli in awake rats by varying the interstimulus interval. The stimuli were: (i) two noise bursts; (ii) two unilateral electrical stimuli near the principal nucleus of the trigeminal nerve; (iii) electrical stimulation of the left and right trigeminal nucleus; or (iv) a noise burst and unilateral stimulation of the trigeminal nucleus. Following two noise bursts, the amplitude of startle increased as the interval increased from 0 to 4 ms, then declined smoothly as the interval increased to 15 ms. Unilateral stimulation of the trigeminal nucleus resulted in a sharper summation effect, with maximal summation at 2 ms, and refractory periods estimated at 0.4-0.8 ms. Bilateral stimulation of the trigeminal nucleus resulted in broader summation without a refractory period, and maximal summation when the stimuli on both sides of the trigeminal nucleus were presented simultaneously. The combination of acoustic and trigeminal stimulation was most effective in enhancing startle amplitudes, and summation peaked when the noise burst preceded the trigeminal stimulation by 5 ms. Similarly, electromyogram latencies measured in the hindlimb were 3-4 ms shorter for trigeminal stimulation than for the noise burst. Startle appears to be optimally activated by simultaneous acoustic and tactile stimuli, as occurs during head blows.

[1]  Younglim Lee,et al.  A Primary Acoustic Startle Pathway: Obligatory Role of Cochlear Root Neurons and the Nucleus Reticularis Pontis Caudalis , 1996, The Journal of Neuroscience.

[2]  J. Siegel,et al.  Anatomical distribution and response patterns of reticular neurons active in relation to acoustic startle , 1988, Brain Research.

[3]  B. Frost,et al.  Azimuthal sensitivity of rat pinna reflex: EMG recordings from cervicoauricular muscles , 1996, Hearing Research.

[4]  T. Blumenthal,et al.  The startle response and auditory temporal summation in neonates. , 1987, Journal of experimental child psychology.

[5]  M. Schmolesky,et al.  The effect of acoustic pulse intensity upon the electrically elicited blink reflex at positive and negative stimulus onset asynchronies , 1996, Biological Psychology.

[6]  Michael Davis,et al.  The design and calibration of a startle measurement system , 1986, Physiology & Behavior.

[7]  P. Groves,et al.  Brain stem pathways, cortical modulation, and habituation of the acoustic startle response. , 1974, Behavioral biology.

[8]  G. Hammond,et al.  Augmentation of the early component of the human blink reflex with closely spaced stimulus pairs , 1993, Psychobiology.

[9]  B. Taylor,et al.  Dissociation of tactile and acoustic components in air puff startle , 1991, Physiology & Behavior.

[10]  Michael Davis,et al.  NMDA and non-NMDA antagonists infused into the nucleus reticularis pontis caudalis depress the acoustic startle reflex , 1993, Brain Research.

[11]  J. Yeomans,et al.  Axons and synapses mediating electrically evoked startle: collision tests and latency analysis , 1995, Brain Research.

[12]  J. Yeomans,et al.  Double-pulse stimulation of startle-like responses in rats: refractory periods and temporal summation , 1989, Brain Research.

[13]  G. Hammond.  Lesions of pontine and medullary reticular formation and prestimulus inhibition of the acoustic startle reaction in rats. , 1973, Physiology & behavior.

[14]  G. Hammond,et al.  Temporal integration shown in the late component of the human blink reflex , 1997, Psychobiology.

[15]  J. Yeomans,et al.  Axons and synapses mediating startle-like responses evoked by electrical stimulation of the reticular formation in rats: symmetric and asymmetric collision effects , 1993, Brain Research.

[16]  G. Paxinos,et al.  The Rat Brain in Stereotaxic Coordinates , 1983 .

[17]  T. Blumenthal,et al.  Modification of the electrically elicited eyeblink by acoustic, visual, and vibrotactile pulses , 1997, Psychobiology.

[18]  J. Siegel,et al.  Behavioral organization of reticular formation: studies in the unrestrained cat. II. Cells related to facial movements. , 1983, Journal of neurophysiology.

[19]  J. Pellet.  Neural organization in the brainstem circuit mediating the primary acoustic head startle: An electrophysiological study in the rat , 1990, Physiology & Behavior.

[20]  T. Blumenthal,et al.  The startle response as an indicator of temporal summation , 1986, Perception & psychophysics.

[21]  Temporal integration in the acoustic startle reflex of the rat. , 1973, Journal of comparative and physiological psychology.

[22]  J. Ostwald,et al.  Afferent and efferent connections of the ventrolateral tegmental area in the rat , 1997, Anatomy and Embryology.

[23]  H. Hoffman,et al.  The neural substrate of the startle response , 1980, Physiology & Behavior.

[24]  M. Davis,et al.  Footshock-induced sensitization of electrically elicited startle reflexes. , 1989, Behavioral neuroscience.

[25]  E Friauf,et al.  Giant neurons in the rat reticular formation: a sensorimotor interface in the elementary acoustic startle circuit? , 1994, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[26]  H. Schnitzler,et al.  Acoustic startle threshold of the albino rat (Rattus norvegicus). , 1987, Journal of comparative psychology.

[27]  T. Blumenthal,et al.  The startle eyeblink response to low intensity acoustic stimuli. , 1991, Psychophysiology.

[28]  Geoffrey R. Hammond,et al.  Temporal integration of acoustic and cutaneous stimuli shown in the blink reflex , 1989, Perception & psychophysics.

[29]  Michael Davis.  The Mammalian Startle Response , 1984 .

[30]  J. Yeomans,et al.  Collision-like interactions between acoustic and electrical signals that produce startle reflexes in reticular formation sites , 1993, Brain Research.

[31]  M. Davis,et al.  A primary acoustic startle circuit: lesion and stimulation studies , 1982, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[32]  Paul W. Frankland,et al.  The acoustic startle reflex: neurons and connections , 1995, Brain Research Reviews.

[33]  K. Kandler,et al.  Auditory projections from the cochlear nucleus to pontine and mesencephalic reticular nuclei in the rat , 1991, Brain Research.

[34]  J. Siegel,et al.  Behavioral organization of reticular formation: studies in the unrestrained cat. I. Cells related to axial, limb, eye, and other movements. , 1983, Journal of neurophysiology.

[35]  E. Friauf,et al.  Giant neurons in the caudal pontine reticular formation receive short latency acoustic input: An intracellular recording and HRP‐study in the rat , 1992, The Journal of comparative neurology.

[36]  J. Yeomans.  Principles of Brain Stimulation , 1990 .

[37]  M. Davis,et al.  Plasticity of the acoustic startle response in the acutely decerebrate rat. , 1977, Journal of comparative and physiological psychology.

[38]  M. Koch,et al.  Loss of the acoustic startle response following neurotoxic lesions of the caudal pontine reticular formation: Possible role of giant neurons , 1992, Neuroscience.