Fig. 3: Flexible cache memories. | Nature Communications

Fig. 3: Flexible cache memories.

From: Computational models of episodic-like memory in food-caching birds

Fig. 3

In the second experiment of Clayton03, birds cached crickets on day 1 in caching tray 1. In the Plastic Caching Model, an available food item activates a food-type neuron ϕf and the food indicator neuron ϕ* and a caching tray activates cache-site neurons ϕx that code for the tray’s appearance and position in the cage. The caching preference ϕcache depends on the current motivational state hf weighted by \({v}_{f}^{{{{{{{{\rm{cache}}}}}}}}}\) and the caching weights \({w}_{fx}^{{{{{{{{\rm{cache}}}}}}}}}\). Memory weights \({w}_{fx}^{(1)}\) (blue arrows) are tagged when the bird evaluates the caching preference and grown after successful caching. Caching on day 2 in tray 2 (not shown) and on day 3 in caching tray 3 (same position, different appearance than tray 1) leads to the formation of new memory weights (blue arrows). Memory consolidation over night (wiggly gray arrows) transferred the memory of the caching event on day 1 to weights that target the third layer of the associative memory (dashed blue arrows). The caching event on day 2 is stored in memory weights that target the second layer (not shown). Perceiving caching tray 1 on day 4 activates the memory of the food type cached in this tray. This activates the foodtype neuron ϕf, the foodtype-specific caching neuron \({\phi }_{f}^{{{{{{{{\rm{cache}}}}}}}}}\) and the readout of the motivational state. The food indicator neuron ϕ* is inactive, because the food item is not actually perceived but only remembered. The inspection preference ϕinspect depends on the current motivational state hf weighted by \({v}_{f}^{{{{{{{{\rm{inspect}}}}}}}}}\) and the memory readout weights \({v}_{f}^{(4)}\). The unpleasant feedback of the degraded recovered cricket (thick gray arrows) decreases the caching weights \({w}_{fx}^{{{{{{{{\rm{cache}}}}}}}}}\) and the memory readout weights \({v}_{f}^{(4)}\). These weights are further lowered on day 5 (not shown). Consequently, on day 6 the bird has a lower preference of inspecting the tray where it cached a cricket three days ago.

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