Spiking regimes in model networks of hippocampal persistent firing neurons
Year: 2016
Type: conference-paper
Abstract: Rapid persistent firing is thought to be the neural correlate of short-term memory maintenance [1],in which transient stimuli must be preserved during long delay periods outlasting them. Therefore,the brain structures commonly involved in working memory tasks, including the hippocampus, mustpossess the necessary substrates for the generation and maintenance of elevated persistent activity.Various synaptic mechanisms underlying mnemonic persistent firing have been suggested by neuroscientists. The common view is that networks with specific topologies, such as recurrent excitatoryconnections, depend on strong local excitation for the generation of long-lasting neuronal activity andrhythmic oscillations [2]. However, it has been shown that memory can also be encoded in brainregions which do not display such topologies, such as the CA1 area of the hippocampus [3]. Theseregions display similar activation patterns, and must therefore rely on mechanisms which are independent of topology and connectivity, such as intrinsic cellular properties. Among these are the ioniccurrents mediated by calcium-activated non-specific (CAN) ion channels, which seem to be a validcandidate for rhythm generators in hippocampal networks.Our work investigates the different patterns of activity displayed by model networks of hippocampalCAN-equipped persistent firing neurons. The neuron model is based on the Hodgkin-Huxley formalism for increased biological plausibility. We show that synchronized patterns elicited by a transient(250 ms) stimulus can be maintained solely by CAN currents, without the need for strong recurrentconnections. In addition, such a CAN-network exhibits three main types of firing regimes dependingon the value of the connection weights – a slow regime with firing rates 6 Hz < f < 18 Hz, a burstingregime, and a fast gamma regime with firing rates f > 40 Hz. These results are in accordance within vitro recordings of hippocampal slice preparations [4], and provide a possible explanation for thegeneration and maintenance of memory-related oscillatory activity in different frequency bands, withinthe hippocampus.
Source: HAL
Institutions: Monash University, Ruhr University Bochum
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2616387001