Infraslow noradrenergic locus coeruleus activity fluctuations are gatekeepers of the NREM-REM sleep cycle.

The noradrenergic locus coeruleus (LC) regulates arousal levels during wakefulness, but its role in sleep remains unclear. Here, we show in mice that fluctuating LC neuronal activity partitions non-rapid-eye-movement sleep (NREMS) into two brain-autonomic states that govern the NREMS-REMS cycle over ~50-s periods; high LC activity induces a subcortical-autonomic arousal state that facilitates cortical microarousals, whereas low LC activity is required for NREMS-to-REMS transitions. This functional alternation regulates the duration of the NREMS-REMS cycle by setting permissive windows for REMS entries during undisturbed sleep while limiting these entries to maximally one per ~50-s period during REMS restriction.

Emerging Functions of Neuromodulation during Sleep.

Neuromodulators act on multiple timescales to affect neuronal activity and behavior. They function as synaptic fine-tuners and master coordinators of neuronal activity across distant brain regions and body organs. While much research on neuromodulation has focused on roles in promoting features of wakefulness and transitions between sleep and wake states, the precise dynamics and functions of neuromodulatory signaling during sleep have received less attention.

Silencing CA1 pyramidal cells output reveals the role of feedback inhibition in hippocampal oscillations.

The precise temporal coordination of neural activity is crucial for brain function. In the hippocampus, this precision is reflected in the oscillatory rhythms observed in CA1. While it is known that a balance between excitatory and inhibitory activity is necessary to generate and maintain these oscillations, the differential contribution of feedforward and feedback inhibition remains ambiguous.

Cortical sensory processing across motivational states during goal-directed behavior.

Behavioral states can influence performance of goal-directed sensorimotor tasks. Yet, it is unclear how altered neuronal sensory representations in these states relate to task performance and learning. We trained water-restricted mice in a two-whisker discrimination task to study cortical circuits underlying perceptual decision-making under different levels of thirst.

Learning-related congruent and incongruent changes of excitation and inhibition in distinct cortical areas.

Excitatory and inhibitory neurons in diverse cortical regions are likely to contribute differentially to the transformation of sensory information into goal-directed motor plans. Here, we investigate the relative changes across mouse sensorimotor cortex in the activity of putative excitatory and inhibitory neurons-categorized as regular spiking (RS) or fast spiking (FS) according to their action potential (AP) waveform-comparing before and after learning of a whisker detection task with delayed licking as perceptual report. Surprisingly, we found that the whisker-evoked activity of RS versus FS neurons changed in opposite directions after learning in primary and secondary whisker motor cortices, while it changed similarly in primary and secondary orofacial motor cortices.

Axonal and Dendritic Morphology of Excitatory Neurons in Layer 2/3 Mouse Barrel Cortex Imaged Through Whole-Brain Two-Photon Tomography and Registered to a Digital Brain Atlas.

Communication between cortical areas contributes importantly to sensory perception and cognition. On the millisecond time scale, information is signaled from one brain area to another by action potentials propagating across long-range axonal arborizations. Here, we develop and test methodology for imaging and annotating the brain-wide axonal arborizations of individual excitatory layer 2/3 neurons in mouse barrel cortex through single-cell electroporation and two-photon serial section tomography followed by registration to a digital brain atlas.

Rapid suppression and sustained activation of distinct cortical regions for a delayed sensory-triggered motor response.

The neuronal mechanisms generating a delayed motor response initiated by a sensory cue remain elusive. Here, we tracked the precise sequence of cortical activity in mice transforming a brief whisker stimulus into delayed licking using wide-field calcium imaging, multiregion high-density electrophysiology, and time-resolved optogenetic manipulation. Rapid activity evoked by whisker deflection acquired two prominent features for task performance: (1) an enhanced excitation of secondary whisker motor cortex, suggesting its important role connecting whisker sensory processing to lick motor planning; and (2) a transient reduction of activity in orofacial sensorimotor cortex, which contributed to suppressing premature licking.

Cortical circuits for transforming whisker sensation into goal-directed licking.

Animals can learn to use sensory stimuli to generate motor actions in order to obtain rewards. However, the precise neuronal circuits driving learning and execution of a specific goal-directed sensory-to-motor transformation remain to be elucidated. Here, we review progress in understanding the contribution of cortical neuronal circuits to a task in which head-restrained water-restricted mice learn to lick a reward spout in response to whisker deflection.

Anatomically and functionally distinct thalamocortical inputs to primary and secondary mouse whisker somatosensory cortices.

Subdivisions of mouse whisker somatosensory thalamus project to cortex in a region-specific and layer-specific manner. However, a clear anatomical dissection of these pathways and their functional properties during whisker sensation is lacking. Here, we use anterograde trans-synaptic viral vectors to identify three specific thalamic subpopulations based on their connectivity with brainstem.

Distinct Contributions of Whisker Sensory Cortex and Tongue-Jaw Motor Cortex in a Goal-Directed Sensorimotor Transformation.

The neural circuits underlying goal-directed sensorimotor transformations in the mammalian brain are incompletely understood. Here, we compared the role of primary tongue-jaw motor cortex (tjM1) and primary whisker sensory cortex (wS1) in head-restrained mice trained to lick a reward spout in response to whisker deflection. Two-photon microscopy combined with microprisms allowed imaging of neuronal network activity across cortical layers in transgenic mice expressing a genetically encoded calcium indicator.

Continuous wavelet application for the assessment of neural potential interaction during time discrimination task.

The aim of the paper is to assess the interaction of the neural potentials during a time discrimination psychoacoustic task. Ten subjects participated in the experiment and were asked about the equality of two acoustic pulses: one reference of 500ms and one trial that varied from 420ms to 620ms. During the experimental procedure, Electroencephalogram (EEG) and Event Related Potential (ERP) signals were recorded.