A new type of pyramidal neuron in the hippocampus promotes sequence replay

To investigate the potential impact of novel athorny pyramidal cells on sequence replay events associated with sharp wave-ripple oscillations, we established two network models of the hippocampal CA3 region from a modeling perspective. In model 1, the pyramidal cells population was considered homogenous, generating regular-spike firing patterns. In model 2, the pyramidal cells population was heterogeneous and included a new type of pyramidal neuron capable of burst firing—athorny pyramidal cells. By analyzing sequence replay phenomena in both networks and examining the relative time order of synchronous firing between the two types of pyramidal neurons around synchronous events, we arrived at the following conclusions: (1) The novel athrony pyramidal cells enhance the frequency of sequence replay events and promote sharp wave-ripple occurrences. (2) We hypothesize that this facilitation may be attributed to athrony pyramidal cells potentially triggering synchronous events when their firing rate reaches a certain threshold. This is supported by our observation that synchronous firing of athorny pyramidal cells precedes that of thorny pyramidal cells during sharp-wave ripple events commonly associated with sequence replay. Our model demonstrates the critical role of novel athorny pyramidal cells in hippocampal information processing and memory consolidation mechanisms. These findings have significant implications for understanding hippocampal function and memory processes.