Fig. 6: Network mechanisms of diverse spiking irregularity and its invariance during attention.
From: A doubly stochastic renewal framework for partitioning spiking variability
a The model comprises three layers representing the thalamus, V1, and MT, implemented as spatially organized spiking networks (upper panel). Layer 1 consists of 2500 excitatory Poisson neurons firing at a uniform rate of 10 Hz. Layers 2 and 3 are recurrently coupled balanced networks, each containing 40,000 excitatory and 10,000 inhibitory neurons. Layer 2 receives feedforward excitatory input from Layer 1, and the excitatory neurons in Layer 2 project to Layer 3. Within Layers 2 and 3, neurons form spatially structured recurrent connections, with connection probability decaying with distance according to a Gaussian profile (lower panel; color intensity indicates connection probability). b Distributions of spiking irregularity (ϕ) for excitatory (blue) and inhibitory (red) neurons in Layer 2 (solid lines) and Layer 3 (dashed lines). The diversity of spiking irregularity across Layer 2 neurons aligns with experimental observations (cf. Fig. 4). Excitatory neurons in Layer 3 exhibit highly regular spiking, while inhibitory neurons display a broad range of spiking irregularity. c Spiking irregularity of neurons in Layer 2 decreases with the firing rate (blue dots—excitatory neurons, red dots—inhibitory neurons, lines—linear regression). d Spiking irregularity of neurons in Layer 2 decreases with the balance in the total number of excitatory and inhibitory connections received by a neuron nfe + nee−nie. e Attentional modulation of FF, spiking irregularity ϕ, and firing rate variability Var(λT) in Layer 3. The FF modulation index (MI) is defined as (FFattended−FFunattended)/(FFattended + FFunattended), and similarly for spiking irregularity and firing rate variability. FF is significantly reduced during attention (left, ***p < 10−10, n = 35, 944, one-sided t-test), driven by an attention-mediated reduction in firing rate variability (right, ***p < 10−10), while spiking irregularity remains unchanged (center, ns, p = 0.51). The dashed red line marks zero, and the blue triangle indicates the mean of the distribution. Source data are provided as a Source data file.
