whale exchangers-022410

whale exchangers-022410 - 14. 15. 16. 17. 18. 19. 20. 21....

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Scalaidhe, C. G. Gross, J. Neurophysiol. 70 , 1115 (1993). 14. Monkeys were trained by successive approxima- tion to fixate within 2.0° of the fixation point. If the animal’s eye position left the fixation window, the fixation light extinguished, no reward was deliv- ered, anda1s time-out was imposed in addition to the intertrial interval. A trial consisted of: fixation of a centrally presented fixation point for 0.5 s, 1.0 s of visual stimulus presentation, followed by an addi- tional 0.5 s of fixation. No behavioral response oth- er than visual fixation was required, and stimuli were presented in a randomized order. Every neu- ron was tested on one or more basic sets of color stimuli presented on a computer monitor including faces, objects, and colored rectangles. Stimuli typ- ically subtended 8° to 10° of visual angle and were presented on a monitor with 640 pixel by 400 pixel resolution and 16-bit color. In two of three mon- keys, when neurons appeared to show selectivity for faces, they were then tested exhaustively with additional stimuli to assess the basis for an appar- ent selective response to a face stimulus. 15. The mean firing rate was calculated for five time intervals for the task: 1 s during the pretrial period preceding the onset of the fixation point, 400 ms starting 100 ms after visual fixation, 200 ms begin- ning 100 ms after presentation of the visual stimulus, 900 ms from 100 ms after onset of the visual stimu- lus, and 2000 ms starting 100 ms after offset of the visual stimulus. An analysis of variance (ANOVA) was then performed using stimulus as a factor and firing rate in the time windows as a factor with repeated measures. The ANOVA yielded P values for the ef- fects of time period, stimulus, and interaction be- tween stimulus and time period. Only neurons with a significant main effect of stimulus or a significant interaction between stimulus and time window and a significant one-way ANOVA for one of the cue peri- ods or the postcue period at a level of P , 0.05 were considered selectively responsive. Using the criteria of Perret and colleagues ( 20 ), cells that met the ANOVA criteria and had a response magnitude to the best face stimulus that was more than twice as strong as the best response to a nonface stimulus were considered to be face-selective. 16. E. L. Schwartz, R. Desimone, T. D. Albright, C. G. Gross, Proc. Natl. Acad. Sci. U.S.A. 80 , 5776 (1983); E. T. Rolls and G. C. Baylis, Exp. Brain Res. 65 , 38 (1986); G. Sa ´ ry, R. Vogels, G. A. Orban, Science 260 , 995 (1993). 17. Offset of response was determined by when the response returned to below (or above) a 95% confi- dence interval based on pretrial firing for at least 100 ms [J. M. MacPherson and J. W. Aldridge, Brain Res. 175
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This note was uploaded on 03/22/2011 for the course CHE 120B taught by Professor Zasadinski during the Winter '10 term at UCSB.

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