Journal of Comparative Physiology A

, Volume 194, Issue 8, pp 693–700 | Cite as

Stimulus-dependent oscillations and evoked potentials in chinchilla auditory cortex

  • Paul H. Delano
  • Elizabeth Pavez
  • Luis Robles
  • Pedro E. Maldonado
Original Paper


Besides the intensity and frequency of an auditory stimulus, the length of time that precedes the stimulation is an important factor that determines the magnitude of early evoked neural responses in the auditory cortex. Here we used chinchillas to demonstrate that the length of the silent period before the presentation of an auditory stimulus is a critical factor that modifies late oscillatory responses in the auditory cortex. We used tetrodes to record local-field potential (LFP) signals from the left auditory cortex of ten animals while they were stimulated with clicks, tones or noise bursts delivered at different rates and intensity levels. We found that the incidence of oscillatory activity in the auditory cortex of anesthetized chinchillas is dependent on the period of silence before stimulation and on the intensity of the auditory stimulus. In 62.5% of the recordings sites we found stimulus-related oscillations at around 8–20 Hz. Stimulus-induced oscillations were largest and consistent when stimuli were preceded by 5 s of silence and they were absent when preceded by less than 500 ms of silence. These results demonstrate that the period of silence preceding the stimulus presentation and the stimulus intensity are critical factors for the presence of these oscillations.


Auditory cortex Chinchilla Oscillations Local field potential Tetrode 



Evoked potential


Local field potential



We thank Bethany Schneider, Fernando Ramirez and Carlos Hamamé for comments on a previous version of the manuscript and Fernando Vergara for technical assistance. This work was supported by FONDECYT 1020970, Iniciativa Científica Milenio ICM P01-007F, PhD Scholarship CONICYT to PHD and PG-42-2004. The experiments reported here comply with the “Principles of Animal Care” (publication No. 86-23, revised 1985 of the NIH) and also with the current Chilean laws (CBA #098 FMUCH).


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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Paul H. Delano
    • 1
    • 3
    • 4
  • Elizabeth Pavez
    • 1
    • 2
  • Luis Robles
    • 1
  • Pedro E. Maldonado
    • 1
    • 3
  1. 1.Programa de Fisiología y Biofísica, ICBM, Facultad de MedicinaUniversidad de ChileSantiago 7Chile
  2. 2.Escuela de Tecnología Médica, Facultad de MedicinaUniversidad de ChileSantiagoChile
  3. 3.Centro de Neurociencias Integradas, ICMSantiagoChile
  4. 4.Servicio Otorrinolaringología, Hospital Clínico de la Universidad de ChileSantiagoChile

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