Fig 6. Cognitive tasks.

Schematic representation of the tasks and the input/output data structure for each of the cognitive tasks used to evaluate the performance of the BioESNs. Left: Memory capacity (MC) task, where the network receives a stream of random values as single input X and has several independent outputs Y (for simplicity, the example shows only two. Each output is memorized by an independent output neuron of the network and is supposed to recall the input at a specific time lag τ. The BioESNs were trained with 4000 time steps and tested on the subsequent 1000. Right: One trial of the sequence recall task. The network receives inputs X₁, X₂ coming from a random sequence and a recall signal channel, respectively. There is only one output neuron, which after the recall signal channel indicates it (i.e., X₂ = 1) is supposed to reproduce the input received in the previous L steps, i.e., the pattern length parameter determining the difficulty of the task (for simplicity, in the scheme L = 2). The BioESNs were trained with 800 trials and tested on 200 trials. The score was computed considering only the recall phase in order to avoid inflation of the metric, given that the fixation periods were much easier to perform correctly.