No abstract

Astrocytes, glial cells of the central nervous system, help to regulate neural circuit operation and adaptation. They exhibit complex forms of chemical excitation, most prominently calcium transients, evoked by neuromodulator and -transmitter receptor activation. However, whether and how astrocytes contribute to cortical processing of complex behavior remains unknown. One of the puzzling features of astrocyte calcium transients is the high degree of variability in their spatial and temporal patterns under behaving conditions. Here, we provide mechanistic links between astrocytes' activity patterns, molecular signaling, and behavioral cognitive and motor activity variables by employing a visual detection task that allows for in vivo calcium imaging, robust statistical analyses, and machine learning approaches. We show that trial type and performance levels deterministically shape astrocytes' spatial and temporal response properties. Astrocytes encode the animals' decision, reward, and sensory properties. Our error analysis confirms that astrocytes carry behaviorally relevant information depending on and complementing neuronal coding. We also report that cell-intrinsic mechanisms curb astrocyte calcium activity. Additionally, we show that motor activity-related parameters strongly impact astrocyte responses and must be considered in sensorimotor study designs. Our data inform and constrain current models of astrocytes' contribution to complex behavior and brain computation beyond their established homeostatic and metabolic roles.

Spinal cord circuits play crucial roles in transmitting and gating cutaneous somatosensory modalities, such as pain, but the underlying activity patterns within and across spinal segments in behaving mice have remained elusive. To enable such measurements, we developed a wearable widefield macroscope with a 7.9 mm2 field of view, subcellular lateral resolution, 2.7 mm working distance, and <10 g overall weight. We show that highly localized painful mechanical stimuli evoke widespread, coordinated astrocyte excitation across multiple spinal segments.

While the spinal cord is known to play critical roles in sensorimotor processing, including pain-related signaling, corresponding activity patterns in genetically defined cell types across spinal laminae have remained challenging to investigate. Calcium imaging has enabled cellular activity measurements in behaving rodents but is currently limited to superficial regions. Here, using chronically implanted microprisms, we imaged sensory and motor-evoked activity in regions and at speeds inaccessible by other high-resolution imaging techniques. To enable translaminar imaging in freely behaving animals through implanted microprisms, we additionally developed wearable microscopes with custom-compound microlenses. This system addresses multiple challenges of previous wearable microscopes, including their limited working distance, resolution, contrast, and achromatic range. Using this system, we show that dorsal horn astrocytes in behaving mice show sensorimotor program-dependent and lamina-specific calcium excitation. Additionally, we show that tachykinin precursor 1 (Tac1)-expressing neurons exhibit translaminar activity to acute mechanical pain but not locomotion.

While the spinal cord is known to play critical roles in sensorimotor processing, including pain-related signaling, corresponding activity patterns in genetically defined cell types across spinal laminae have remained elusive. Calcium imaging has enabled cellular activity measurements in behaving rodents but is currently limited to superficial regions. Using chronically implanted microprisms, we imaged sensory and motor evoked activity in regions and at speeds inaccessible by other high-resolution imaging techniques. To enable translaminar imaging in freely behaving animals through implanted microprisms, we additionally developed wearable microscopes with custom-compound microlenses. This new integrated system addresses multiple challenges of previous wearable microscopes, including their limited working distance, resolution, contrast, and achromatic range. The combination of these innovations allowed us to uncover that dorsal horn astrocytes in behaving mice show somatosensory program-dependent and lamina-specific calcium excitation. Additionally, we show that tachykinin precursor 1 (Tac1)-expressing neurons exhibit upper laminae-restricted activity to acute mechanical pain but not locomotion.