Experimental Brain Research

, Volume 91, Issue 3, pp 435–454 | Cite as

A comparison of monaural and binaural responses to frequency modulated (FM) sweeps in cat primary auditory cortex

  • J. R. Mendelson
  • K. L. Grasse


Monaural and binaural single unit responses to frequency-modulated (FM) sweeps were compared in cat primary auditory cortex (AI). Both upward-directed (changing from low to high frequency) and downward-directed (changing from high to low frequency) FM sweeps were presented monaurally and binaurally at five rates of frequency modulation (referred to here as the speed of FM sweep). Two types of binaural FM sweep conditions were presented: (1) like-directed FM sweeps, in which identical FM sweeps were presented to both ears, and (2) opposite-directed FM sweeps, in which one ear was presented with one direction of FM sweep while the other ear was simultaneously presented with the opposite direction of FM sweep. In a sample of 78 cells, 33 cells were classified as EE (binaural facilitatory) and 45 were classified as EI (binaural inhibitory). Ninety-four percent of all units were sensitive to the direction and/or speed of FM sweeps. In general, under binaural stimulus conditions, EE cells responded optimally to like-directed FM sweeps, while EI cells preferred opposite-directed FM sweeps. When tested monaurally, 59% of all cells (both EE and EI) were direction selective, with the majority (76%) preferring downward-directed FM sweeps. When tested binaurally, most direction selective EE cells (60%) preferred upward-directed FM sweeps, while the majority of direction selective EI cells (71%) preferred downward-directed FM sweeps. Our analysis also allowed us to classify inhibitory responses of EI cells as either direction selective (37%) or non-direction selective (63%). For FM speed selectivity under monaural conditions, most EE cells preferred fast FM sweep rates (0.4–0.8 kHz/ms), while approximately equal numbers of EI cells preferred either slow (i.e., 0.05–0.1 kHz/ms) or fast (i.e., 0.4–0.8 kHz/ms) speeds. Under binaural conditions, the majority of EE and EI cells responded best to high speeds when tested with like-directed FM sweeps, while the preferred speed with opposite-directed FM sweeps was more broadly tuned. The results suggest the presence of binaural neural mechanisms underlying cortical FM sweep direction and speed selectivity.

Key words

Frequency modulated sweep Binaural response Primary auditory cortex Direction selectivity Speed selectivity Cat 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Arthur RM, Pfeiffer RR, Suga N (1971) Properties of “two tone inhibition” in primary auditory neurones. J Physiol (Lond) 212:593–609Google Scholar
  2. Britt R, Starr A (1976) Synaptic events and discharge patterns of cochlear nucleus. II. Frequency modulated tones. J Neurophysiol 31:179–193Google Scholar
  3. Clopton BM, Winfield JA (1974) Unit responses in the inferior colliculus of rat to temporal auditory patterns of tone sweeps and noise bursts. Exp Neurol 42:532–540Google Scholar
  4. Cynader M, Chernenko G (1976) Abolition of direction selectivity in the visual cortex of the cat. Science 193:504–505Google Scholar
  5. Cynader M, Regan D (1978) Neurones in cat parastriate cortex sensitive to the direction of motion in three-dimensional space. J Physiol (Lond) 274:549–569Google Scholar
  6. Cynader M, Regan D (1982) Neurons in cat visual cortex tuned to the direction of motion in depth: effect of positional disparity. Vision Res 22:967–982Google Scholar
  7. Erulkar SD, Butler RA, Gerstein GL (1968) Excitation and inhibition in cochlear nucleus. II. Frequency-modulated tones. J Neurophysiol 31:637–648Google Scholar
  8. Gardner RB, Wilson JP (1979) Evidence for direction-specific channels in the processing of frequency modulation. J Acoust Soc Am 66:704–709Google Scholar
  9. Grasse KL, Ariel M, Smith ID (1990) Direction-selective responses of units in the dorsal terminal nucleus of cat following intravitreal injections of bicuculline. Vis Neurosci 6:604–617Google Scholar
  10. Kay RH (1982) Hearing of modulation in sounds. Physiol Rev 62:894–975Google Scholar
  11. Kay RH, Matthews DR (1972) On the existence in human auditory pathways of channels selectively tuned to the modulation present in frequency-modulated tones. J Physiol (Lond) 225:657–677Google Scholar
  12. Mendelson JR (1992) Neural selectivity for interaural frequency disparity in cat primary auditory cortex. Hear Res 58:47–56Google Scholar
  13. Mendelson JR, Cynader MS (1985) Sensitivity of cat primary auditory cortex (AI) neurons to the direction and rate of frequency modulation. Brain Res 327:331–335Google Scholar
  14. Mendelson JR, Schreiner CE, Sutter ML, Grasse KL (1992) Functional topography of cat primary auditory cortex: responses to frequency modulated sweeps. Exp Brain Res (in press)Google Scholar
  15. Merzenich MM, Knight PL, Roth GL (1975) Representation of cochlea within primary auditory cortex in the cat. J Neurophysiol 38:231–249Google Scholar
  16. Moller AR (1974) Coding of sounds with rapidly varying spectrum in the cochlear nucleus. J Acoust Soc Am 55:631–640Google Scholar
  17. Moody DB, May B, Cole DM, Stebbins WC (1986) The role of frequency modulation in the perception of complex stimuli by primates. Exptal Biol 45:219–232Google Scholar
  18. Nabelek IV, Nabelek AK, Hirsh IJ (1970) Pitch of tone bursts of changing frequency. J Acoust Soc Am 48:536–553Google Scholar
  19. Nabelek IV, Nabelek AK, Hirsh IJ (1972) Pitch of sound bursts with continuous or discontinuous change of frequency. J Acoust Soc Am 53:1305–1312Google Scholar
  20. Nelson PG, Erulkar SD, Bryan JS (1966) Responses of units of the inferior colliculus to time-varying acoustic stimuli. J Neurophysiol 29:834–860Google Scholar
  21. Nomoto M (1980) Discharge patterns of the primary auditory cortex in cats. Jpn J Physiol 30:427–442Google Scholar
  22. Phillips DP, Mendelson JR, Cynader MS, Douglas RM (1985) Responses of single neurones in cat auditory cortex to time-varying stimuli: frequency-modulated tones of narrow excursion. Exp Brain Res 58:443–454Google Scholar
  23. Phillips DP, Hall SE (1987) Responses of single neurons in cat auditory cortex to time-varying stimuli: linear amplitude modulations. Exp Brain Res 67:479–492Google Scholar
  24. Pick GF (1979) A study of frequency transition in cat vocalization. J Acoust Soc Am 66:594–597Google Scholar
  25. Poon PWF, Chen X, Hwang JC (1991) Basic determinants for FM responses in the inferior colliculus of rats. Exp Brain Res 83:598–606Google Scholar
  26. Rees A, Moller AR (1983) Responses of neurons in the inferior colliculus of the rat to AM and FM tones. Hearing Res 10:301–330Google Scholar
  27. Regan D, Tansley BW (1979) Selective adaptation to frequency-modulated tones: Evidence for an information-processing channel selectively sensitive to frequency changes. J Acoust Soc Am 65:1249–1257Google Scholar
  28. Sachs MB, Kiang NYS (1968) Two-tone inhibition in auditory nerve fibers. J Acoust Soc Am 43:1120–1128Google Scholar
  29. Sellick PM, Russell IJ (1979) Two tone suppression in cochlear hair cells. Hear Res 1:227–236Google Scholar
  30. Shore SE, Nuttall AL (1985) High-synchrony cochlear compound action potentials evoked by rising frequency-swept tone bursts. J Acoust Soc Am 78:1286–1295Google Scholar
  31. Shore SE, Clopton BM, Au YN (1987) Unit responses in ventral cochlear nucleus reflect cochlear coding of rapid frequency-sweeps. J Acoust Soc Am 82:471–478Google Scholar
  32. Sinex DG, Geisler CD (1981) Auditory-nerve fiber responses to frequency-modulated tones. Hearing Res 4:127–148Google Scholar
  33. Suga N (1965a) Functional properties of auditory neurones in the cortex of echo-locating bats. J Physiol (Lond) 181:671–700Google Scholar
  34. Suga N (1965b) Analysis of frequency modulated sounds by auditory neurons of echo-locating bats. J Physiol (Lond) 179:26–53Google Scholar
  35. Suga N (1968) Analysis of frequency-modulated and complex sounds by single auditory neurones of bats. J Physiol (Lond) 198:51–80Google Scholar
  36. Suga N (1969) Classification of inferior collicular neurones of bats in terms of responses to pure tones, FM sounds, and noise bursts. J Physiol 200:555–574Google Scholar
  37. Tansley BW, Regan D (1979) Separate auditory channels for unidirectional frequency modulation and unidirectional amplitude modulation. Sensory Proc 3:132–140Google Scholar
  38. Vartanian IA (1974) On mechanisms of specialized reactions of central auditory neurons to frequency-modulated sounds. Acustica 31:305–310Google Scholar
  39. Watanabe T (1972) Fundamental study of the neural mechanisms in cats subserving the feature extraction process of complex sounds. Jpn J Physiol 22:569–583Google Scholar
  40. Whitfield IC, Evans EF (1965) Responses of auditory cortical neurons to stimuli changing frequency. J Neurophysiol 28:655–672Google Scholar
  41. Whitfield IC, Purser D (1972) Microelectrode study of the medial geniculate body in unanesthetized free-moving cats. Brain Behav Evol 6:311–322Google Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • J. R. Mendelson
    • 1
  • K. L. Grasse
    • 2
  1. 1.Division of Life SciencesUniversity of TorontoScarboroughCanada
  2. 2.Department of PsychologyYork UniversityNorth YorkCanada

Personalised recommendations