Article Figures & Data
Figures
- Figure 1.
Freely-moving setup and basic stimulus design. A, Schematic of freely-moving behavioral setup. The trial initiation port was centered on the wall opposite the visual display. Choice ports were on either side of the display. An IR beam was also placed across the middle of the box. B, Task structure. An LED was illuminated above the trial initiation port to signal that the ferret could initiate a trial. When the ferret broke the IR beam in that port, a small reward was dispensed, and stimulus presentation was triggered. Subsequent selection of the correct port resulted in ending stimulus presentation and reward delivery. C & D, Acuity task stimuli: sinusoidal gratings with varying contrasts and spatial frequencies. The ferrets were trained to discriminate horizontal from vertical gratings. E, Motion integration task stimuli: RDK consisting of black and white dots with varying coherence levels. RDK had to be discriminated based on their direction of motion (left or right). F, Form integration task stimuli: linear Glass patterns with varying degrees of coherence. The ferrets were trained to discriminate horizontal from vertical patterns.
- Figure 2.
Behavioral estimates of visual acuity. A, Psychometric curves for one ferret (F4) for three spatial frequencies. Error bars represent 95% confidence intervals (see Materials and Methods). B, Psychometric curves fit to data from individual testing sessions using a spatial frequency of 0.18 cpd (ferret F4); 13 sessions are shown here. C, Contrast sensitivity curves for each ferret. Error bars represent 68% confidence intervals (see Materials and Methods).
- Figure 3.
Motion integration thresholds. A, Psychometric curves for each ferret on the motion integration task (dot speed 48°/s). B, Impact of training on motion integration thresholds: performance for F4 at the time of initial threshold measurements, and after 11 additional sessions. C, Sided coherence threshold Δ as a function of dot speed for each ferret. D, Performance of ferret F4 for RDK of 60% coherence as a function of dot speed. E, Performance comparison for short versus infinite dot lifetime (data for ferret F0). F, Performance comparison for white dots on a black background versus black and white dots on a gray background (data for ferret F6). All error bars, with exception of C, represent 95% confidence intervals. Error bars for C are 68% confidence intervals.
- Figure 4.
Head-fixed behavior paradigm. A, Schematic drawing of the head-fixed behavior setup (top view). The setup consisted of three major components, a body holder, headpost holder, and the reward spouts. All three components could be moved relative to each other to allow the animal to assume a comfortable posture while in the setup, and to reach the spouts easily. Each spout could be moved independently between a retracted and a forward position by means of a gas piston. Animals could only lick the spouts when in the forward position. All spouts were mounted on a large translation stage to control their overall distance from the animal. In addition, the two peripheral spouts were mounted on two smaller translation stages to control the lateral distance between the spouts. This was necessary to make sure that animals could not activate more than one spout simultaneously. B, Side-view of the head-fixed behavior setup. C, Three-spout task design. A trial initiation cue was presented and the center spout was moved forward. When the ferret licked the center spout, a small reward was dispensed. Next, the center spout was retracted and stimulus presentation was triggered. The two choice spouts were moved forward. If the ferret licked the correct spout first, the incorrect spout was retracted, the stimulus removed, and the ferret received a large water reward. If the ferret contacted the incorrect spout first, it was also retracted. The ferret then had to contact the correct spout (which remained in position) to end the trial and receive a much smaller reward.
- Figure 5.
Comparison of motion integration thresholds measured using head-fixed and freely-moving paradigms. Psychometric curves from all ferrets for the motion integration task at 72°/s. Colored lines show the performance of the head-fixed animals, F8 and F9. Black lines show the performance of freely moving animals (F0, F4, and F6). Error bars represent 95% confidence intervals.
- Figure 6.
Form integration thresholds measured using Glass patterns. Psychometric curves for Glass pattern stimuli for two ferrets. Error bars represent 95% confidence intervals.
- Figure 7.
Comparison of neurometric and psychometric motion integration thresholds. A, Sagittal view of the ferret brain, with the suprasylvian sulcus (SS) and PSS indicated. B, Firing rate distributions for an example PSS neuron, evoked by RDK of different coherence levels moving in the neurons preferred direction (black bars) or its null direction (white bars). Each bar indicates the number of trials on which a neuron exhibited a particular firing rate. C, ROC curves generated from the distributions in B. D, aROC values for all directionally selective and significantly responsive neurons (N = 36) at 100% coherence. Red dashed line at 0.75 indicates criterion cutoff. E, Comparison of an example neurometric function, computed for the neuron shown in C, D, to the average psychometric function. The average psychometric function was generated by fitting behavioral data collapsed across all three ferrets tested in the freely-moving paradigm. The threshold for the average psychometric function, using a criterion of 75% correct responses, is also indicated. Error bars indicate 95% confidence intervals. F, Distribution of 75% correct coherence thresholds across all directionally selective, significantly responsive neurons with aROC values of 0.75 or above at 100% coherence (N = 34). Also shown are the mean of this distribution, the threshold based on the average psychometric function (see E), and the thresholds of each of the three ferrets, all using the same criterion of 75% correct.
Tables
Ferret Acuity Dots Glass F0 X X X F4 X X F2 X F6 X X F8 X F9 X Ferrets were first trained on the Acuity task, followed by the RDK task, followed by the Glass pattern task.
Ferret Peak contrast sensitivity (cpd) Maximum acuity estimate (cpd) Number of trials Number of sessions F0 0.17 0.70 1420 11 F2 0.17 0.60 1500 17 F4 0.20 0.65 1291 13 Mean 0.18 ± 0.01 0.65 ± 0.03 1404 ± 61 14 ± 2 Mean reported with SE.
Task Δ (50–68%) Threshold at 75% Threshold at 82% Number of trials Number of sessions Dots, 72°/s F0 20.06% 35.62% 45.07% 1371 12 F4 14.05% 23.39% 32.17% 503 6 F6 12.79% 26.74% 34.98% 778 7 Mean, free 15.63 ± 2.24% 28.58 ± 2.65% 37.40 ± 3.92% 884 ± 256 8 ± 2 F9 (hf) 18.36% 30.55% 41.62% 568 4 F8 (hf) 28.35% 45.27% 59.48% 939 2 Mean, hf 23.36 ± 5.00% 37.91 ± 7.36% 50.55 ± 8.93% 753 ± 186 3± 1 Mean, all 18.72 ± 2.75% 32.31 ± 3.83% 42.66 ± 4.79% 832 ± 155 6 ± 2 Dots, 48°/s F0 18.93% 42.96% 49.98% 308 3 F4 15.01% 25.10% 35.56% 581 5 F6 18.91% 34.51% 47.76% 707 8 Mean 17.62 ± 1.30% 34.19 ± 5.16% 44.43 ±4.48% 532 ± 118 5 ± 1 Dots, 24°/s F0 19.89% 38.37% 50.89% 570 5 F4 17.67% 39.16% 47.37% 492 5 F6 16.67% 33.97% 44.20% 749 8 Mean 18.07 ± 0.95% 37.16 ± 1.61% 47.49 ± 1.93% 604 ± 76 6 ± 1 Glass F0 21.32% 44.31% 66.68% 766 6 F6 23.25% 48.94% 65.45% 616 5 Mean 22.28 ± 0.97% 46.65 ± 2.34% 66.06 ± 0.62% 691 ± 75 6 ± 1 Hf, head-fixed behavior; free, freely-moving behavior. Mean reported with SE.
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