the three types of neurons are located in brainstem.
the three types of neurons are located in brainstem.
where are the three types of neurons located?
brainstem
the last decades of work in the perl laboratory were principally devoted to characterizing the functional organization of the superficial dorsal horn of the spinal cord and understanding how spinal neurons located within these regions interact with one another to process signals arising from the periphery. these experiments involved recording from neurons responsive to various types of primary afferent input and correlating these functional signatures with morphological features of the spinal neurons in question. this work in part resulted in the systematic categorization by timothy grudt and perl of functionally characterized spinal neurons based on their morphological features and location within the dorsal horn. experiments with yan lu and jihong zheng were aimed at a better understanding of connections between spinal neurons and how afferent input from the periphery is modulated by these connections. perl’s experiments with adam hantman focused on a unique, homogeneous population of green fluorescent protein (gfp)-expressing neurons in the spinal substantia gelatinosa of a transgenic mouse. hantman and perl physiologically characterized these neurons, showing them to be inhibitory in nature and responsive only to unmyelinated afferents with a conduction velocity at the high end of the c-fiber range; they also demonstrated the highly specific connections of these gfp-expressing neurons with other types of neurons in the substantia gelatinosa.
edward perl
the olivocochlear bundle (ocb) originates in the superior olivary complex in the brainstem. the vestibulocochlear anastomosis carries the efferent axons into the cochlea, where they innervate the organ of corti (oc). the ocb contains fibres projecting to both the ipsilateral and contralateral cochleae, prompting an initial division into crossed (cocb) and uncrossed (ucocb) systems. more recently, however, the division of the ocb is based on the cell bodies’ site of origin in the brainstem relative to the medial superior olive (mso). the medioventral periolivary (mvpo) region, also known as the ventral nucleus of the trapezoid body, a diffuse region of neurons located medial to the mso, gives rise to the medial olivocochlear system (mocs). the lateral superior olive (lso), a distinct nucleus of neurons located lateral to the mso, gives rise to the lateral olivocochlear system (locs). the mocs neurons are large multipolar cells, while the locs are classically defined as composed of small spherical cells. this division is viewed as being more meaningful with respect to ocb physiology. in addition to these classically defined olivocochlear neurons, advances in tract tracing methods helped reveal a third class of olivocochlear neurons, termed shell neurons, which surround the lso. thus, locs class cell bodies within the lso are referred to as intrinsic locs neurons, while those surrounding the lso are referred to as shell, or extrinsic, locs neurons. shell neurons are typically large, and morphologically are very similar to mocs neurons.
olivocochlear system