Fig. 4: Sensory and categorical neurons and their coding dynamics.
Periodicity mutual information (IPer, Eq. (10)) and 1 s firing rate mutual information (I1s,P1, Eq. (6)) associated with pattern identity were used to identify sensory and categorical S2 neuron subpopulations. a Exemplary S2 neuron with high periodicity information during the first stimulation period (IPer = 0.89bits). This neuron demonstrates low values of I1s,P1 (I1s,P1 = 0.07bits). We can label it as a member of the sensory subgroup. b S2 neuron with low periodicity (IPer = 0.04bits) information and a marked categorical response for E pattern. This neuron conveys large values of I1s,P1 (I1s,P1 = 0.83bits), so it was labeled as categorical. c For each S2 neuron recorded during the TPDT (n = 1646), I1s,P1 (x-axis) is plotted against IPer (y-axis), both associated with the identity of P1. Analogous P2 results were omitted. The red dashed lines indicate the arbitrary mutual information criteria (I > 0.25bits) used to label S2 neurons as sensory (y-axis) or categorical (x-axis). Arbitrary boundaries isolate dynamics features in S2 network based on dominant information value (IPer or I1s,P1). Most S2 neurons exhibit low or intermediate values for both I1s,P1 and IPer (green points). d I1s,P1 (x-axis) is plotted against IPer (y-axis) for each S2 neuron recorded during the LCT (n = 313). Negligibly few neurons exhibit I1s,P1 > 0.25bits during the LCT. e–h Percentage of each subpopulation of neurons with significant coding as a function of time during the TPDT or the LCT. Traces refer to P1 (cyan), P2 (green), class (pink), and decision coding (black). e–f Sensory neurons (IPer > 0.25bits) during the TPDT (right, n = 105) or the LCT (left, n = 41). Most sensory neurons only involved in coding P1 or P2 identity during stimulation periods. g–h Categorical neurons computed during the first stimulus (I1s,P1 > 0.25bits, n = 150) or second stimulus (I1s,P2 > 0.25bits, n = 184) periods. In both cases, P1 coding emerges later and remains longer than in sensory neurons; class coding is present in both categorical neuron types. Decision coding after “pu” is observed in both categorical and sensory neurons during the TPDT. No categorical neurons were identified during the LCT for computing coding dynamics.
