Data from: Synchronized excitability in a network enables generation of internal neuronal sequences

Hippocampal place field sequences are supported by sensory cues and
network internal mechanisms. In contrast, sharp-wave (SPW) sequences,
theta sequences, and episode field sequences are internally generated. The
relationship of these sequences to memory is unclear. SPW sequences have
been shown to support learning and have been assumed to also support
episodic memory. Conversely, we demonstrate these SPW sequences were
present in trained rats even after episodic memory was impaired and after
other internal sequences – episode field and theta sequences – were
eliminated. SPW sequences did not support memory despite continuing to
‘replay’ all task-related sequences – place- field and episode field
sequences. Sequence replay occurred selectively during synchronous
increases of population excitability -- SPWs. Similarly, theta sequences
depended on the presence of repeated synchronized waves of excitability –
theta oscillations. Thus, we suggest that either intermittent or rhythmic
synchronized changes of excitability trigger sequential firing of neurons,
which in turn supports learning and/or memory.