Humans must quickly and accurately redirect their gaze in order to look at new targets of interest. Thus, the gaze system must respond to sensory input with precise movement of the eyes and head to correctly position gaze on that target. The central Mesencephalic Reticular Formation (cMRF) interacts with the superior colliculus (SC) and the paramedian pontine reticular formation (PPRF) to control movement of the eyes. However, the signals carried by neurons in these regions are very different. SC neurons respond for a subset of movements, thus the SC is spatially encoded. The excitatory burst neurons (EBNs) in the PPRF change their firing rate with changes in the amplitude and velocity of the movement, thus the EBNs are temporally encoded. How a transformation from spatial to temporal encoding occurs between these two regions is not known. As a major recipient of input from the SC and with direct projections to the PPRF, the cMRF is ideally situated to perform this transformation. Indeed, neurons in the cMRF have BOTH spatial and temporal characteristics. Our current hypothesis is that cMRF pre-saccadic neurons provide the physiologic machinery to perform a spatial to temporal transformation. This proposal will examine cMRF neurons during behaviors that permit comparison of saccades of different velocities, but similar amplitudes to discern whether cMRF neurons temporally encode eye movement velocity. This will be coupled with analysis of the neurons spatial properties and antidromic stimulation to confirm downstream projections.
| Waitzman, David M; Van Horn, Marion R; Cullen, Kathleen E (2008) Neuronal evidence for individual eye control in the primate cMRF. Prog Brain Res 171:143-50 |
| Cromer, Jason A; Waitzman, David M (2007) Comparison of saccade-associated neuronal activity in the primate central mesencephalic and paramedian pontine reticular formations. J Neurophysiol 98:835-50 |
| Cromer, Jason A; Waitzman, David M (2006) Neurones associated with saccade metrics in the monkey central mesencephalic reticular formation. J Physiol 570:507-23 |
