Abstract
The thalamus is a key element of sensory transmission in the brain, as it gates and selects sensory streams through a modulation of its internal activity. A preponderant role in these functions is played by its internal activity in the alpha range ([8–14] Hz), but the mechanism underlying this process is not completely understood. In particular, how do thalamocortical connections convey stimulus driven information selectively over the back-ground of thalamic internally generated activity? Here we investigate this issue with a spiking network model of feedforward connectivity between thalamus and primary sensory cortex reproducing the local field potential of both areas. We found that in a feedforward network, thalamic oscillations in the alpha range do not entrain cortical activity for two reasons: (i) alpha range oscillations are weaker in neurons projecting to the cortex, (ii) the gamma resonance dynamics of cortical networks hampers oscillations over the 10–20 Hz range thus weakening alpha range oscillations. This latter mechanism depends on the balance of the strength of thalamocortical connections toward excitatory and inhibitory neurons in the cortex. Our results highlight the relevance of corticothalamic feedback to sustain alpha range oscillations and pave the way toward an integrated understanding of the sensory streams traveling between the periphery and the cortex.
Highlights
During the past decades several key features of sensory processing in the primary sensory cortex have been discovered, but much less is known about sensory information processing and transmission in the thalamus (Rikhye et al 2018)
We investigated in silico the properties of thalamocortical information transmission through our local network model of the thalamus receiving external stimuli (Barardi et al 2016) and projecting to the primary cortex, which receives stimulus-unrelated excitatory inputs (Mazzoni et al 2011) (Fig. 1A)
To capture the mechanisms underlying the relationship between spectral content in the thalamus and in the cortex, we first compared the thalamic PSDT and the associated cortical PSDΓ from the respective LFPs both without external stimuli and during external stimulation, see “Methods” and (Barardi et al 2016)
Summary
During the past decades several key features of sensory processing in the primary sensory cortex have been discovered, but much less is known about sensory information processing and transmission in the thalamus (Rikhye et al 2018). The majority of sensory signals are conveyed by the thalamus to the cortex in the form of spiking patterns propagating along different pathways (Kandel et al 2000). Thalamocortical relay neurons in the thalamus receive sensory inputs and in turn project them to particular areas of the cortex through thalamocortical synapses. The thalamus has been described as a relay station where little computation takes place. We investigate the interplay of these two functions of the thalamus, using a novel spiking network model of the two areas
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