Our objective is to understand how the nervous system translates sensory information into the commands for the initiation and execution of movements. The saccadic eye movement system, because of its simple peripheral mechanics and musculature and the ease with which eye movements can be quickly and accurately recorded, has lent itself to a rapid accumulation of detailed knowledge of the neuron types, the discharge patterns, and many of the connections that comprise the brainstem saccade generator. That understanding is incomplete, and has therefore been supplemented wiht hypothesized connections and neuron types and formulated in the form of models that simulate a functioning saccade generator. We will test which of two models of the saccade generator best predicts the eye movement that results from specific chemical lesions to one of its component elements, the omnipause neurons. The results of the lesion studies will tell us something of how the elements of the saccade generator must be configured to produce normal saccades. We will also study the inputs to the brainstem saccade generator. We will focus on mesencephalic saccade-related neurons located in regions known to project to the region of omnipause neurons. Their discharge patterns will be quantified and related to the parameters of the saccade. The discharge will also be tested under a variety of behavioral conditions designed to reveal a variety of possible functional roles. Finally, the connections of mesencephalic saccade-related neurons with putative target neurons in the pontine saccade generator as well as the superior colliculus will be investigated. To assist in assessing connections, we will attempt to develop a technique, peri-spike histograms, for use in alert trained animals. The description of discharge characteristics and the demonstration of connections of particular types of neurons will help us to understand the next most central level of processing in the programming of saccadic eye movements. These studies, in addition to providing an example of how the nervous system processes information, provide a list of specific functions that can be attributed to specific neural areas of structures. That list has proven to be and should continue to be very useful in the diagnosis and localization of nervous system dysfunctions from a wide variety of causes, especially since the eye movements are easily monitored and deficits quickly revealed.
NIH ExPorter
NIH ExPorter