Temporal refinement of sensory‐evoked activity across layers in developing mouse barrel cortex

Abstract

Rhythmic whisking behavior in rodents fully develops during a critical period about 2 weeks after birth, in parallel with the maturation of other sensory modalities and the onset of exploratory locomotion. How whisker‐related sensory processing develops during this period in the primary somatosensory cortex (S1) remains poorly understood. Here, we characterized neuronal activity evoked by single‐ or dual‐whisker stimulation patterns in developing S1, before, during and after the occurrence of active whisking. Employing multi‐electrode recordings in all layers of barrel cortex in urethane‐anesthetized mice, we find layer‐specific changes in multi‐unit activity for principal and neighboring barrel columns. While whisker stimulation evoked similar early responses (0–50 ms post‐stimulus) across development, the late response (50–150 ms post‐stimulus) decreased in all layers with age. Furthermore, peak onset times and the duration of the late response decreased in all layers across age groups. Responses to paired‐pulse stimulation showed increases in spiking precision and in paired‐pulse ratios in all cortical layers during development. Sequential activation of two neighboring whiskers with varying stimulus intervals evoked distinct response profiles in the activated barrel columns, depending on the direction and temporal separation of the stimuli. In conclusion, our findings indicate that the temporal sharpening of sensory‐evoked activity coincides with the onset of active whisking.

Sensory input drives rapid homeostatic scaling of the axon initial segment in mouse barrel cortex

“…Furthermore, studies in sensory cortices of various rodent species have outlined a layerspecific ability for plastic adaptation reflected by changes in spine dynamics, synaptic plasticity or direct stimulation responses both during development as well as at mature ages (Jiang et al, 2007;Skibinska et al, 2000;van der Bourg et al, 2017;van der Bourg et al, 2019). These studies showed that synaptic scaling and spine dynamics are a predominant feature of supragranular layers and to a much lesser extent for infragranular layers, underscoring our data showing layer-specific AIS plasticity.…”

A database and deep learning toolbox for noise-optimized, generalized spike inference from calcium imaging

“…5 , 6 ). The enhanced temporal resolution will be particularly useful for the analysis of neuronal activity during natural stimulus sequences and behaviors that occur on timescales shorter than typical durations of calcium transients, such as dynamical neuronal representations across theta cycles 52 or early and late phases of sensory responses in cortical areas 53 . Moreover, the inference of absolute spike rates will help improve the calibration of precisely patterned optogenetic manipulations 54 , 55 and the extraction of constraints, e.g., absolute spike rates, for computational models of neural circuits.…”

Spontaneous activity in developing thalamic and cortical sensory networks

“…Indeed, local responses to single whisker deflection are already observed at P0, and they undergo progressive tuning, which is evidence of a segregated whisker map as early as P2-P3 (Mitrukhina et al, 2015). At the onset of active whisking (P14), localized cortical responses to single whisker deflections will undergo further layer-specific and temporal refinement (van der Bourg et al, 2017(van der Bourg et al, , 2019Yang et al, 2009). In vivo calcium imaging further confirms that the diameter of the domains reaches an average of 300 mm in the presumptive sensory cortices of neonatal rats and mice, whether spontaneous or evoked (Kummer et al, 2016;Nakazawa et al, 2020).…”