Frequency tuning and discharge patterns of spherical bushy cells resemble most closely those of the auditory nerve fibers with which they make synaptic contact and hence are referred to functionally as being “primary-like” (PL).
First, convergence of cochlear input upon a bushy cell is limited to but one (or a few) primary afferent, which tends to preserve the spectral sensitivity and discharge pattern of incoming primary afferents. This highly unusual structure underlies two important functions subserved by bushy cells. Primary afferents make multiple synaptic contacts over almost the entire soma of bushy cells by their large basket-like terminal structures - the end bulbs of Held ( Richter, 1983 Adams, 1986). Spherical and globular bushy cells are distinguished by cytoplasmic features as well as by their rounded somata from which sprout short, bushy primary and secondary dendrites. Nor is a segregation of spherical bushy cells into large and small types evident in humans ( Richter, 1983). Spherical bushy cells, globular bushy cells and stellate cells in the human VCN lie somewhat intermixed within cochlear nerve branches, making it difficult to discern a boundary that in other mammals so often defines anteroventral and posteroventral divisions. Each plays a special role in transforming temporal and spectral information it receives from the cochlea and in transmitting that transformed information over parallel pathways to higher auditory centers of the brain.
These are referred to as spherical bushy cells, globular bushy cells, stellate cells, octopus cells and small cap cells ( Bacsik and Strominger, 1973 Dublin, 1974, 1976 JK Moore and Osen, 1979a,b Richter, 1983 Adams, 1986 JK Moore, 1987 Cant, 1992 Wagoner and Kulesza, 2009). The human VCN consists of five cell types having morphological characteristics of those found in VCN of non-human mammals. Brugge, in Handbook of Clinical Neurophysiology, 2013 2.2.1 Ventral cochlear nucleus
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