Neural circuits and temporal plasticity in hindlimb representation of rat primary somatosensory cortex: revisited by multi-electrode array on brain slices

• Published in: Neuroscience bulletin Vol. 26; no. 3; pp. 175 - 187
• Main Authors: Wang, Dan-Dan, Li, Zhen, Chang, Ying, Wang, Rui-Rui, Chen, Xue-Feng, Zhao, Zhen-Yu, Cao, Fa-Le, Jin, Jian-Hui, Liu, Ming-Gang, Chen, Jun
• Format: Journal Article
• Language: English
• Published: Heidelberg Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences 01.06.2010
• Subjects: Afferent Pathways - physiology; Anatomy; Anesthesiology; Animals; Biomedical and Life Sciences; Biomedicine; Electric Stimulation; Electrodes; Hindlimb - physiology; Human Physiology; In Vitro Techniques; Long-Term Potentiation - physiology; Male; Models, Neurological; Neural Pathways - physiology; Neurology; Neuronal Plasticity - physiology; Neurons - physiology; Neurosciences; Original; Original Article; Pain Medicine; Presynaptic Terminals - physiology; Rats; Rats, Sprague-Dawley; Somatosensory Cortex - physiology; Synaptic Transmission - physiology; Thalamus - physiology; Time Factors; 平面微电极阵列记录技术; 神经回路; primary somatosensory cortex; 二维电流源密度分析; two-dimensional current source density imaging; neural circuits; 长时程增强; 初级躯体感觉皮层; planar multi-electrode array; long-term potentiation
• ISSN: 1673-7067; 1995-8218; 1995-8218
• DOI: 10.1007/s12264-010-0308-6

Objective The well-established planar multi-electrode array recording technique was used to investigate neural circuits and temporal plasticity in the hindlimb representation of the rat primary somatosensory cortex (S1 area). Methods Freshly dissociated acute brain slices of rats were subject to constant perfusion with oxygenated artificial cerebrospinal fluid (95% O 2 and 5% CO 2 ), and were mounted on a Med64 probe (64 electrodes, 8×8 array) for simultaneous multi-site electrophysiological recordings. Current sources and sinks across all the 64 electrodes were transformed into two-dimensional current source density images by bilinear interpolation at each point of the 64 electrodes. Results The local intracortical connection, which is involved in mediation of downward information flow across layers II–VI, was identified by electrical stimulation (ES) at layers II–III. The thalamocortical connection, which is mainly involved in mediation of upward information flow across layers II–IV, was also characterized by ES at layer IV. The thalamocortical afferent projections were likely to make more synaptic contacts with S1 neurons than the intracortical connections did. Moreover, the S1 area was shown to be more easily activated and more intensively innervated by the thalamocortical afferent projections than by the intracortical connections. Finally, bursting conditioning stimulus (CS) applied within layer IV of the S1 area could successfully induce long-term potentiation (LTP) in 5 of the 6 slices (83.3%), while the same CS application at layers II–III induced no LTP in any of the 6 tested slices. Conclusion The rat hindlimb representation of S1 area is likely to have at least 2 patterns of neural circuits on brain slices: one is the intracortical circuit (ICC) formed by interlaminar connections from layers II–III, and the other is the thalamocortical circuit (TCC) mediated by afferent connections from layer IV. Besides, ICC of the S1 area is spatially limited, with less plasticity, while TCC is spatially extensive and exhibits a better plasticity in response to somatosensory afferent stimulation. The present data provide a useful experimental model for further studying microcircuit properties in S1 cortex at the network level in vitro .