Temporal diversity in the cat lateral geniculate nucleus
Purpose. To examine the responses and spatiotemporal receptive field structure of lagged and nonlagged cells and to reconsider the classification of these cells and the effects of parabrachial stimulation. Methods. Extracellular recording in anesthetized, paralyzed cats combined with the use of conventional visual stimuli plus reverse correlation with spatiotemporal ternery white noise. Results. A multi-dimensional cluster analysis was performed based on parameters taken from the measured spatiotemporal weighting functions and the responses to other stimuli for 130 X-cells. This analysis cleaved the population into two groups corresponding closely to our intuitive classification of lagged and nonlagged cells. However, the most reliable feature of lagged cells was not the delayed response, but rather initial inhibition in the response to center-appropriate stimuli. These two features were almost uncorrelated. The initial inhibition was exhibited by all of the lagged cells and by only one of the nonlagged cells. This criterion seems to apply to Y-cells as well. Histograms of individual parameters were seldom distributed in a bimodal fashion. A few lagged cells were found with short half-rise times, and a few nonlagged cells were found with long half-rise times. This classification scheme was robust during parabrachial stimulation. The responses of cells of both types were quite well predicted from their spatiotemporal weighting functions, suggesting a general linearity of response. Conclusions. Although most typical lagged and nonlagged cells show responses that are very different, these cell classes appear to be drawn from populations which overlap extensively on single response measures. The independence of the temporal measurements and the leading inhibition suggests a model including at least two mechanisms. The profound temporal differences between nonlagged and lagged cells may be useful in the generation of spatiotemporal receptive field properties of cortical cells.
Neurology|Anatomy & physiology
Wolfe, Jonathan Nils, "Temporal diversity in the cat lateral geniculate nucleus" (1996). Dissertations available from ProQuest. AAI9628028.