Deep CNNs and Neural Responses

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Questions and Answers

What do the top layers of deeper CNNs predict more accurately than 'regular-deep' models?

  • Challenge images for AlexNet
  • Early phases of IT neural responses
  • Late phases of IT neural responses (correct)
  • Recurrent circuits of the ventral stream

What has been observed for challenge images when using deeper CNNs?

  • The challenge images remain the same
  • An increase in the number of challenge images
  • A reduction in the number of challenge images (correct)
  • No change in the number of challenge images

What is unique about the images that remain unsolved by deeper CNNs?

  • They have shorter OSTs in the IT cortex
  • They are not related to challenge images
  • They have longer OSTs in the IT cortex (correct)
  • They have no OSTs in the IT cortex

What does CORnet model implement?

<p>Within-area recurrent connections with shared weights (A)</p> Signup and view all the answers

What is unique about Pass 4 of the CORnet model?

<p>It is a better predictor of late phases of IT responses (B)</p> Signup and view all the answers

What do the results of CORnet model further argue for?

<p>Recurrent computations in the ventral stream (B)</p> Signup and view all the answers

What do the data not yet explain?

<p>The exact nature of the computational problem solved by recurrent circuits (C)</p> Signup and view all the answers

What is the number of time-steps implemented in the CORnet model?

<p>Five (A)</p> Signup and view all the answers

What happens when an image is rapidly followed by a spatially overlapping mask?

<p>The image is interrupted from further processing (C)</p> Signup and view all the answers

What is a limitation of standard feed-forward models like AlexNet?

<p>They are not robust to occlusion (A)</p> Signup and view all the answers

What is the purpose of adding recurrent connections to the fc7 layer of AlexNet?

<p>To allow the model to perform pattern completion (A)</p> Signup and view all the answers

What is a characteristic of attractor networks like the Hopfield network?

<p>They have all-to-all connections with fixed attractor points (C)</p> Signup and view all the answers

What was observed when evaluating the performance of feed-forward models on partially visible objects?

<p>Performance was comparable to humans at full visibility, but declined at limited visibility (A)</p> Signup and view all the answers

What was found when comparing the latency of neural response and computational distance of each partial object to its whole object category mean?

<p>A modest but significant correlation (B)</p> Signup and view all the answers

What is the name of the model that was developed by adding recurrent connections to the fc7 layer of AlexNet?

<p>RNNh (B)</p> Signup and view all the answers

What is shown in the temporal evolution of the feature representation for RNNh as visualized with stochastic neighborhood embedding?

<p>The iterative refinement of the model's representation (B)</p> Signup and view all the answers

What is the primary advantage of deeper CNNs like Inception-v3 and ResNet-50 compared to shallower networks like AlexNet?

<p>They introduce more nonlinear transformations to the image pixels (C)</p> Signup and view all the answers

What is the primary function of recurrent computations in the primate brain during core object recognition?

<p>To act as additional nonlinear transformations of the initial feedforward (D)</p> Signup and view all the answers

What is the primary purpose of pattern completion in perception?

<p>To enable recognition of poorly visible or occluded objects (A)</p> Signup and view all the answers

What is the result of backward masking on visual object recognition?

<p>It disrupts recognition of partially visible objects (D)</p> Signup and view all the answers

What can be inferred from the representation of whole objects and partial objects in the study?

<p>Partial objects are more similar to each other than to their whole object counterparts. (A)</p> Signup and view all the answers

What is the minimum percentage of object visibility required for the visual system to make inferences?

<p>10% (C)</p> Signup and view all the answers

What happens to the representation of partial objects over time in the clusters of whole images?

<p>They approach the correct category. (A)</p> Signup and view all the answers

What is the primary finding of Tang et al.'s (2018) study on pattern completion?

<p>Pattern completion is implemented by recurrent computations (A)</p> Signup and view all the answers

What is the timing of the saturating performance and correlation with humans in the RNNh model?

<p>Around 10-20 time steps. (B)</p> Signup and view all the answers

What is the result of visual categorization of objects under limited visibility?

<p>Recognition is robust to limited visibility (B)</p> Signup and view all the answers

What is the effect of backward masking on the RNN model's performance?

<p>It impairs the performance. (C)</p> Signup and view all the answers

What is the primary difference between the visual system and current computer vision models?

<p>The visual system has a more efficient implementation of recurrent circuits (C)</p> Signup and view all the answers

What cognitive process is critical for recognition of poorly visible or occluded objects?

<p>Pattern completion. (D)</p> Signup and view all the answers

What is the timing of the physiological responses to heavily occluded objects?

<p>Around 200 ms. (D)</p> Signup and view all the answers

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Study Notes

Deeper CNNs and IT Neural Responses

  • Deeper CNNs, such as Inception-v3 and ResNet-50, predicted IT neural responses at late phases (150-250 ms) more accurately than shallower models like AlexNet.
  • This suggests that deeper CNNs might be approximating 'unrolled' versions of recurrent circuits in the ventral stream.
  • Deeper CNNs had fewer challenge images, and the remaining challenge images showed longer OSTs (object-selective tolerance) in the IT cortex.

CORnet Model

  • CORnet is a four-layered recurrent neural network model that better predicts IT responses, especially in the late phase.
  • The top layer of CORnet has within-area recurrent connections with shared weights and implements five time-steps.
  • Pass 1 and pass 2 of the network are better predictors of early time bins, while late passes (especially pass 4) are better at predicting late phases of IT responses.

Recurrent Computations in the Ventral Stream

  • Deeper CNNs partially approximate recurrent computations in the ventral stream, which are more efficiently built into the primate brain architecture.
  • During core object recognition, recurrent computations act as additional nonlinear transformations of the initial feedforward process.

Image Completion and RNN

  • Recurrent computations are necessary for visual pattern completion, enabling recognition of poorly visible or occluded objects.
  • The visual system can make inferences even when only 10-20% of the object is visible.

Backward Masking

  • Backward masking disrupts recognition of partially visible objects by interrupting processing of the visual stimulus.
  • Behavioral performance declined at limited visibility, and standard feed-forward models were not robust to occlusion.

RNNh Model

  • The RNNh model, which added recurrent connections to the fc7 layer, demonstrated a significant improvement over the standard AlexNet architecture.
  • The RNNh model's performance and correlation with humans saturated at around 10-20 time steps.
  • The model's performance was impaired by backward masking, reducing it from 58 ± 2% to 37 ± 2%.

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