Journal of Neurophysiology, Vol 42, Issue 6 1626-1639, Copyright © 1979 by APS

ARTICLES

Representation of sound frequency and laterality by units in central nucleus of cat inferior colliculus

M. N. Semple and L. M. Aitkin

1. The discharges of 632 units were isolated extracellularly during 42 penetrations of the central nucleus of the inferior colliculus (ICC) in 21 adult cats lightly anesthetized with pentobarbital and ketamine. Microelectrode penetrations were directed from caudal to rostral through ICC, parallel to the Horsley-Clarke (H-C) horizontal and sagittal planes. 2. The threshold best frequency (BF) and binaural response properties were examined for each unit, with the aim of elucidating the organization of these discharge characteristics within ICC. 3. Binaural unit classes consisted of monaural (contralateral) (EO), binaurally phase-sensitive (delay), contralateral excitatory/ipsilateral inhibitory (EI), binaurally excitatory (EE), and other more heterogeneous interaction patterns (other). 4. Detailed histological reconstruction of electrode tracks allowed the recording site for each unit to be related to the three dimensions of ICC. This structure was divided into three lateromedial and three rostrocaudal blocks such that each block contained a similar number of units, enabling meaningful statistical comparisons. Low (3.2 kHz greater than BF) and high (3.2 kHz less than BF) best-frequency classes provided a correlate of dorsoventral location. 5. The arrangements of BFs within ICC were found to be compatible with a model of this structure in which units having similar BFs are organized into layers lying in the H-C horizontal plane medially and gradually tilting in both a ventrolateral and ventrorostral direction. Low frequencies are concentrated dorsally and laterally; high frequencies, ventrally and medially. A rostrocaudal BF difference arises only in lateral aspects of the ICC, where lower frequencies are encountered rostrally. 6. Binaural response classes were distributed differentially throughout ICC. Thus, EO units were concentrated caudally, ventrally, and laterally, while delay units were in greatest numbers rostrally, dorsally, and laterally--almost totally segregated from EO and EI units. The latter populations overlapped ventrally and laterally, but EI units were in greatest density rostrally. The EE class occurred throughout the nucleus, but was most common medially. 7. It is suggested that the differential distributions of binaural responses reflect a partial segregation of the afferents, arising in the superior olive and cochlear nucleus, which terminate in ICC. The central nucleus of the inferior colliculus thus may be composed of several functionally segregated subregions contained within a common tonotopic organization.

This article has been cited by other articles:

				M. S. Malmierca, M. A. Izquierdo, S. Cristaudo, O. Hernandez, D. Perez-Gonzalez, E. Covey, and D. L. Oliver A Discontinuous Tonotopic Organization in the Inferior Colliculus of the Rat J. Neurosci., April 30, 2008; 28(18): 4767 - 4776. [Abstract] [Full Text] [PDF]

				M. N. Shivdasani, S. J. Mauger, G. D. Rathbone, and A. G. Paolini Inferior Colliculus Responses to Multichannel Microstimulation of the Ventral Cochlear Nucleus: Implications for Auditory Brain Stem Implants J Neurophysiol, January 1, 2008; 99(1): 1 - 13. [Abstract] [Full Text] [PDF]

				K. K. Porter, R. R. Metzger, and J. M. Groh Visual- and saccade-related signals in the primate inferior colliculus PNAS, November 6, 2007; 104(45): 17855 - 17860. [Abstract] [Full Text] [PDF]

				H. H. Lim and D. J. Anderson Spatially Distinct Functional Output Regions within the Central Nucleus of the Inferior Colliculus: Implications for an Auditory Midbrain Implant J. Neurosci., August 8, 2007; 27(32): 8733 - 8743. [Abstract] [Full Text] [PDF]

				H. H. Lim and D. J. Anderson Auditory Cortical Responses to Electrical Stimulation of the Inferior Colliculus: Implications for an Auditory Midbrain Implant J Neurophysiol, September 1, 2006; 96(3): 975 - 988. [Abstract] [Full Text] [PDF]

				P. X. JORIS, C. E. SCHREINER, and A. REES Neural Processing of Amplitude-Modulated Sounds Physiol Rev, April 1, 2004; 84(2): 541 - 577. [Abstract] [Full Text] [PDF]

				S. M. N. Woolley and J. H. Casseday Response Properties of Single Neurons in the Zebra Finch Auditory Midbrain: Response Patterns, Frequency Coding, Intensity Coding, and Spike Latencies J Neurophysiol, January 1, 2004; 91(1): 136 - 151. [Abstract] [Full Text]

				S. J. Sterbing, K. Hartung, and K.-P. Hoffmann Spatial Tuning to Virtual Sounds in the Inferior Colliculus of the Guinea Pig J Neurophysiol, October 1, 2003; 90(4): 2648 - 2659. [Abstract] [Full Text] [PDF]

				L. M. Miller, M. A. Escabi, H. L. Read, and C. E. Schreiner Spectrotemporal Receptive Fields in the Lemniscal Auditory Thalamus and Cortex J Neurophysiol, January 1, 2002; 87(1): 516 - 527. [Abstract] [Full Text] [PDF]

				F. E. N. LeBeau, M. S. Malmierca, and A. Rees Iontophoresis In Vivo Demonstrates a Key Role for GABAA and Glycinergic Inhibition in Shaping Frequency Response Areas in the Inferior Colliculus of Guinea Pig J. Neurosci., September 15, 2001; 21(18): 7303 - 7312. [Abstract] [Full Text] [PDF]

				M. L. Gabriele, J. K. Brunso-Bechtold, and C. K. Henkel Plasticity in the Development of Afferent Patterns in the Inferior Colliculus of the Rat after Unilateral Cochlear Ablation J. Neurosci., September 15, 2000; 20(18): 6939 - 6949. [Abstract] [Full Text] [PDF]

				R. K. Shepherd, J. H. Baxi, and N. A. Hardie Response of Inferior Colliculus Neurons to Electrical Stimulation of the Auditory Nerve in Neonatally Deafened Cats J Neurophysiol, September 1, 1999; 82(3): 1363 - 1380. [Abstract] [Full Text] [PDF]

				A. Klug, E. E. Bauer, and G. D. Pollak Multiple Components of Ipsilaterally Evoked Inhibition in the Inferior Colliculus J Neurophysiol, August 1, 1999; 82(2): 593 - 610. [Abstract] [Full Text] [PDF]

				K. A. Davis, R. Ramachandran, and B. J. May Single-Unit Responses in the Inferior Colliculus of Decerebrate Cats II. Sensitivity to Interaural Level Differences J Neurophysiol, July 1, 1999; 82(1): 164 - 175. [Abstract] [Full Text] [PDF]

				B. Delgutte, P. X. Joris, R. Y. Litovsky, and T. C. T. Yin Receptive Fields and Binaural Interactions for Virtual-Space Stimuli in the Cat Inferior Colliculus J Neurophysiol, June 1, 1999; 81(6): 2833 - 2851. [Abstract] [Full Text] [PDF]

				D. A. Bodnar and A. H. Bass Midbrain Combinatorial Code for Temporal and Spectral Information in Concurrent Acoustic Signals J Neurophysiol, February 1, 1999; 81(2): 552 - 563. [Abstract] [Full Text] [PDF]

				M. S. Malmierca, T. B. Leergaard, V. M. Bajo, J. G. Bjaalie, and M. A. Merchan Anatomic Evidence of a Three-Dimensional Mosaic Pattern of Tonotopic Organization in the Ventral Complex of the Lateral Lemniscus in Cat J. Neurosci., December 15, 1998; 18(24): 10603 - 10618. [Abstract] [Full Text] [PDF]