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. 2023 Jun 29;14:3843. doi: 10.1038/s41467-023-39548-5

Fig. 7. Neural Representation Similarity of distributed population-level response and relation to Numerical Distance Effect.

Fig. 7

A, B Neural representation similarity (NRS) calculated based on pairwise similarity between the mean activation across neurons in each layer (a) V1, (b) V2, (c) V3, and (d) IPS, for each value of the input stimuli. This shows us how well differentiated each input stimuli are, compared to other input values, in terms of their neuronal representations, pre-training (A) and post-training (B). The influence of training in the whole layer level RSA can be seen strongly in IPS, to a progressively smaller extent in V3 and negligible in V2 and V1. C, D The NRS is condensed to map the dissimilarity (1- average NRS) averaged as a function of each unique value of difference between inputs, that is, directly measure the numerical distance effect between representations of numerosities at a distributed level. A robust representation should show a sharply increasing linear trend in the average similarity with increasing input difference. The condensed RSA as a function of input difference is calculated for (a) the whole layer, (b) P-SPONs based on selective numerosity neurons, (c) New+Switch based on selective numerosity neurons, (d) P-SPONs based on all numerosity neurons, and (e) New+Switch based on all numerosity neurons. Pre-training (C), these linear trends have a very small slope. This slope increases with numerosity training (D), with significantly larger increases as we move from lower to higher layers, especially in IPS. E, F The NRS is condensed to map the dissimilarity (1- average NRS) averaged as a function of each unique value of log-ratio between inputs, that is, directly measure the ratio effect between representations of numerosities at a distributed level. This is shown for (a) the whole layer, (b) P-SPONs based on selective numerosity neurons, (c) New+Switch based on selective numerosity neurons, (d) P-SPONs based on all numerosity neurons, and (e) New+Switch based on all numerosity neurons. A robust representation should show a sharply increasing linear trend in the average similarity with increasing log-ratio. Source data are provided as a Source Data file.