Probabilistic Reasoning by Neurons
The following supplementary movies are prepared for the journal publication
Yang, T and Shadlen, MN (2007), Probabilistic reasoning by neurons, Nature 447, 1075-1080
These movies reproduce the sequence of events on six representative trials from the experiment. The diagrams in this appendix depict the content of each of the movies. Versions of these diagrams are also reproduced dynamically at the bottom of the movies. Each movie begins with acquisition of the fixation point (FP) and ends with a saccadic eye movement to the red or the green target.
The moving yellow dot shows the eye position of the monkey during the trial. In the bottom of the movie, spike trains are shown as ticks along the time line. The traces depict the changing logLR associated with the appearance of the shapes; height reflects the logLR in favor of Tin. The color of the trace in the movies indicates whether the evidence currently favors the red or the green target. Neither the eye position trace nor the diagrams were shown on the video display that was viewed by the monkey. The movie soundtrack plays the spikes from the neuron. There is a prominent transient response to the targets in the beginning of the 1st epoch. The four shapes cause the firing rate to increase or decrease ~200 ms after each is displayed. Movies 1-3 are from the example neuron depicted in Figure 2 (RF below and to the right of fixation). Movies 4-6 are from three other neurons. All six neurons have their RF location in the right visual field. Note that the same shape can cause different changes of logLR in different epochs (e.g., Movie 1), as explained in Online Methods.
Click the diagrams below to view the movies. Please note that these movies are converted from original .mov format to .m4v format for play in Quicktime 10.4.
A Neural Implementation of Wald's Sequential Probability Ratio Test
The following supplementary movies are prepared for the journal publication
Kira, S., Yang, T., Shadlen, M.N. (2015) A neural implementation of Wald's sequential probability ratio test. Neuron doi: 10.1016/j.neuron.2015.01.007
Movie S1 [related to Figures 3 and 4] . Example trial (Tin choice) with neural recording.
The movie depicts a trial in which monkey E chose the left target (Tin) after viewing 7 shapes. The movie is played at half speed. Eye position is depicted by the yellow dot. After acquiring fixation at the central white dot, two red choice targets appear. The left target is in the RF of the neuron. After a delay, shapes appear sequentially until the monkey initiates its saccade. Action potentials can be heard as clicks. They are also displayed as tick marks above the graph, which shows the cumulative logLR associated with each new shape (horizontal white line segments), displaced by 200 ms relative to the spikes in order to compensate for the sensory delay (τs; see main text). They are thus aligned approximately to the spikes induced by each new shape. The neutral level of evidence (logLR = 0) is shown as a horizontal yellow line. The eye position and lower graph were not displayed to the monkey; nor were the audio clicks. Only the fixation spot, targets, and shapes were visible to the monkey. In this trial, the cumulative logLR meandered around zero for the first few shapes and then favored Tin. Reflecting this pattern, the firing rate increased with the rise in the cumulative logLR until the monkey chose Tin.
Movie S2 [related to Figures 3 and 4]. Example trial (Tout choice) with neural recording.
The recording is from the same LIP neuron as in Movie S1. In this trial, the cumulative logLR initially favored Tin but then reversed to favor Tout. Reflecting this pattern, the firing rate increased initially but then diminished until the monkey chose Tout.