Download dynamics and functional connectivity in barrel network

会员号：S421100710A
Changes
of
Response
Dynamics
and
Functional
Connectivity in Barrel Microcircuit Associated with
Tactile Frequency Discrimination
1
Jun ZHAO , Jin-Hui WANG
1*
1
State Key Laboratory of Brain and Cognitive Sciences，Institute of Biophysics,
Chinese Academy of Sciences, Beijing 100101, China
*Corresponding author
E-mail:[email protected]
Abstract: Objective Cortical processing of somatosensory information is performed
by a large population of neurons with complex dynamics and interactions in barrel
cortex. Emerging evidences recently suggest that astrocytes receive surrounding
synaptic inputs and participate in sensory information processing. However, the
knowledge of population response dynamics and functional connectivity on processing
tactile frequency information in barrel cortex at the level of neuro-astrocytic
microcircuits remains comparably poor. A key step to understand the complex
mechanisms of how these nerve cells work is measuring and analyzing the dynamic
interactions in the local microcircuits in vivo under different conditions of
sensory stimulation. Hence, we used two-photon calcium imaging to monitor the
neuronal and astrocytic activities in barrel microcircuit, which would help to
explore the processing mechanisms for tactile frequency discrimination. Methods FVB
mice (20-35 PND) were anesthetized by the intraperitoneal injections of urethane.
A population of neocortical cells was labeled by injecting the calcium indicator
Oregon Green BAPTA-1 AM into layer I and II/III. Astrocytes were distinguished by
co-injecting the astrocytic specific marker sulforhodamine 101. Population neuronal
and astrocytic calcium signals in barrel microcircuit were simultaneously recorded
in vivo by two-photon laser scanning microscopy with the resolution of individual
cells. Whiskers of FVB mice in the contralateral sides of the imaged barrel cortices
were deflected in a caudal-to-rostral direction by air-puffing during the
experiments. Whisker deflections were done by giving the paired repetitive pulses
of air-puffing (50 psi, 50 ms) through a tiny steel tube that was mounted on a
micromanipulator and controlled with costume-made LabVIEW program. The stimulus
patterns were paired bursts that constituted of frequency patterns as 10 and 10 Hz
(named as 10-to-10 Hz) or 8 and 12 Hz (i.e., 8-to-12 Hz), closely to the natural
frequency of exploratory whisking. The coordination of population calcium dynamics
and network topologic properties were analyzed based on graph theory. Results (1)
Compared with the spontaneous conditions, whiskers deflections evoked much larger
calcium signals in both neurons and astrocytes and increased the activity
synchronization in neuronal and astrocytic network. (2) The majority of neuronal
and astrocytic responses was both facilitated by frequency increment of whiskers
inputs and depressed with the adaptation. (3) Neurons and astrocytes in local
networks were coordinately activated, thus forming functional neuro-astrocytic
network. (4) The strength of functional connectivity in neuro-astrocytic network
was enhanced with frequency increment and weakened with adaptation. Conclusion The
dynamic changes of responses and functional connectivity in barrel neuro-astrocytic
network may contribute to frequency -dependent processing of whisker sensory
information.
Keywords: neuro-astrocyte network; functional connectivity; barrel cortex; sensory
processing; two-photon; calcium imaging