Donders Institute for Brain, Cognition and Behaviour
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Thesis defense Niccolo Calcini (Donders series 409)

19 November 2019

Promotors: prof. dr. T. Celikel, dr. F. Zeldenrust

Principles of intracellular information transfer in the somatosensory cortex

The mammalian neocortex is a complex anatomical network whose function is a by-product of dynamic functional interactions in this network. Although neocortical neurons are diverse in their molecular, anatomical, and electrophysiological properties, they all contribute to the generation of behaviour by integrating and communicating (transmitting) information.
In typical cortical neurons, information processing starts with the integration of synaptic inputs across the dendritic tree which ultimately changes the somatic membrane polarization. The rate-limiting step in neuronal communication, however, is the encoding of subthreshold responses into action potentials (spikes). In this thesis, we numerically quantify the efficacy of this intracellular information transfer as postsynaptic membrane potentials are translated into action
potentials. We show that the capacity for information transfer varies across cell types; while inhibitory neurons more readily transfer somatic depolarizations into action potentials, excitatory neurons perform low-pass frequency filtering. One of the key elements for this cell-type specific information transfer is the adaptive changes in spike threshold, i.e. the membrane potential at which action potentials are generated. The spike threshold is modulated by dopaminergic signalling both in excitatory and inhibitory neurons to control the efficacy of intracellular information transfer as dopaminergic signalling regulates voltage-gated sodium channel conductances. The behavioural outcome of this dopaminergic action is faster sensory integration in freely behaving animals.