The basket cells provided feedback inhibition targeting the cell soma of 70% of all pyramidal neurons within their hypercolumn non-selectively (Yoshimura et al., 2005). Connections between pairs of neurons were randomly

generated according to the connection densities. All connections that a neuron by chance formed onto itself were Venetoclax excluded from the network. The local network connectivity and the corresponding sizes of excitatory postsynaptic potentials (PSPs) were constrained with biological data, mostly from Thomson et al. (2002). For long-range (global) connections data is rather scarce as this type of connectivity is difficult to measure quantitatively. We therefore extrapolated the available experimental data based on theoretical considerations to arrive at a plausible amount of long-range connections between pyramidal cells (Lundqvist et al., 2006 and Lundqvist et al., 2010). Each pyramidal cell had 90 excitatory synapses from other distant pyramidal cells that were part of the same memory pattern. With only 9 hypercolumns in the network this resulted in excessive long-range connectivity density of ~30% (Lundqvist et al., 2006). The density

level is considerably reduced as the number of hypercolumns increases towards selleck real cortical scales. The single cell as well as attractor dynamics are however independent of scale (Djurfeldt et al., 2008). Our neuron models (Lansner and Fransén, 1992) were multi-compartmental and conductance-based, following the Hodgkin–Huxley and Rall formalisms. Pyramidal cells consisted of 6 compartments (soma, basal dendritic, initial segment, and three apical dendritic) and interneurons of 3 compartments (soma, dendritic, and initial segment). The potential in a compartment was calculated by integrating the currents dEdt=(Eleak−E)gm+∑(Ecomp−E)gcore+(Eext−E)gext+Ichannels+Isyncm,where c  m is the capacitance of the membrane proportional to its area, g  m is the membrane leak conductance, E  leak is the equilibrium potential of

the leak current. The term (Ecomp−E)gcore denotes the contributing currents from electrically coupled compartments with potential Ecomp and the conductance gcore, which depends on compartmental cross section (equal for Niclosamide basal and apical dendrites, smaller for initial segment). gext is a non-specific excitatory conductance with reversal potential Eext. Ichannels is the active currents from different ionic channels in the membrane of the compartment, including voltage-dependent Na+, K+, and Ca2+ channels as well as Ca2+-dependent K+ channels. Isyn is the current through glutamatergic (AMPA, NMDA type) and GABA-ergic synapses on the compartment. The kinetics of Ichannels and Isyn are described by Hodgkin–Huxley-type equations presented in Supplementary material. Parameters were tuned to mimic the spiking behavior of the respective neuron type (Table 1). Pyramidal cells were strongly adapting and basket cells almost non-adapting (Cauli et al., 2000).