Biology subjects

Krieger, P.

Publications and source records attributed to Krieger, P..

3 recordsLinked to original sources

bioRxiv2023

Audiovisual stimuli enhance narrowband gamma activity along the mouse thalamocortical visual circuit

To what extent thalamic activity can contribute to multisensory integration at cortical level is unclear. To explore this aspect, we used the mouse narrowband gamma oscillations (NBG), which arise from the lateral geniculate nucleus (LGN) and from upstream retinal inputs, as a tool to investigate potential thalamic audiovisual information transfer to the primary visual cortex (V1). We found that simultaneous bimodal audiovisual stimulation increased the power of V1 NBG. Pharmacological and optogenetic manipulations demonstrated that V1 NBG audiovisual responses occurred independently of primary auditory cortex activation. LGN recordings revealed that the majority of its neurons exhibited audiovisual properties. These properties comprised an increase of both the visual-evoked response and gamma-rhythmicity, indicating that the modulation of V1 NBG by audiovisual stimuli likely has a thalamic origin. Our results reveal a previously unreported subcortical source of audiovisual information transfer in V1 and suggest a new role for the LGN as a multisensory integration and relay center.

neuroscience↗

bioRxiv2022

Reducing Merkel cell activity in the whisker follicle disrupts cortical encoding of whisker movement amplitude and velocity

Merkel cells (MCs) and associated primary sensory afferents of the whisker follicle-sinus complex robustly code whisker self-movement, angle, and whisk phase during whisking. However, direct evidence of their roles in encoding whisker movement at cortical level is currently missing. To this end, spiking activity of primary somatosensory barrel cortex (wS1) neurons was measured in response to varying whisker deflection amplitude and velocity in transgenic mice with previously established reduced mechanoelectrical coupling at MC-associated afferents. Under reduced MC activity, wS1 neurons exhibited increased sensitivity to whisker deflection. This appeared to arise from a lack of variation in response magnitude to varying whisker deflection amplitude and velocity. This latter effect was further indicated by weaker variation in the temporal profile of the evoked spiking activity when whisker deflection amplitude and velocity varied. Nevertheless, under reduced MC activity, wS1 neurons retained the ability to discriminate stimulus features based on the timing of the first post-stimulus spike. Collectively, results from this study suggest that MCs contribute to both cortical encoding of whisker amplitude and velocity predominantly by tuning cortical response magnitude and by patterning evoked spiking activity, rather than in tuning cortical response latency.

neuroscience↗

bioRxiv2017

Chronic silencing of corticothalamic layer 6 pyramidal cells affects cortical excitability and tactile behavior

Cortical projections originating in layer 6 (L6) in mouse primary somatosensory cortex have an important function controlling both cortical and sub-cortical activity. To study cortical plasticity and communication between somatosensory and motor cortex, L6-Ntsr1 cells were chronically silenced using tetanus toxin and the effect this had on cortical activity and behavior was investigated. A 2 Hz stimulation protocol was used to potentiate whisker evoked local field potentials (LFP) in a layer-dependent manner in both cortices. Silencing L6 pyramidal cells, the LFP potentiation in both cortices was affected without a change in the spontaneous multi-unit activity. Animals with L6 chronically silenced used more low-amplitude whisks, which presumably compensates for a reduction in cortical excitability. These results suggest that L6 is not only an important cortical output layer that modulates sub-cortical circuits, but also that it controls cortical dynamics.

neuroscience↗