Impaired Spatial Firing Representations of Neurons in the Medial Entorhinal Cortex of the Epileptic Rat Using Microelectrode Arrays

Zhaojie Xu; Fan Mo; Gucheng Yang; Penghui Fan; Botao Lu; Wei Liang; Fanli Kong; Luyi Jing; Wei Xu; Juntao Liu; Mixia Wang; Yirong Wu; Xinxia Cai

doi:10.34133/research.0229

Impaired Spatial Firing Representations of Neurons in the Medial Entorhinal Cortex of the Epileptic Rat Using Microelectrode Arrays

Research (Wash D C). 2023 Sep 15:6:0229. doi: 10.34133/research.0229. eCollection 2023.

Authors

Zhaojie Xu^{1

2}, Fan Mo^{1

2}, Gucheng Yang^{1

2}, Penghui Fan^{1

2}, Botao Lu^{1

2}, Wei Liang^{1

2}, Fanli Kong^{1

2}, Luyi Jing^{1

2}, Wei Xu^{1

2}, Juntao Liu^{1

2}, Mixia Wang^{1

2}, Yirong Wu^{1

2}, Xinxia Cai^{1

2}

Affiliations

¹ State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

Epilepsy severely impairs the cognitive behavior of patients. It remains unclear whether epilepsy-induced cognitive impairment is associated with neuronal activities in the medial entorhinal cortex (MEC), a region known for its involvement in spatial cognition. To explore this neural mechanism, we recorded the spikes and local field potentials from MEC neurons in lithium-pilocarpine-induced epileptic rats using self-designed microelectrode arrays. Through the open field test, we identified spatial cells exhibiting spatially selective firing properties and assessed their spatial representations in relation to the progression of epilepsy. Meanwhile, we analyzed theta oscillations and theta modulation in both excitatory and inhibitory neurons. Furthermore, we used a novel object recognition test to evaluate changes in spatial cognitive ability of epileptic rats. After the epilepsy modeling, the spatial tuning of various types of spatial cells had suffered a rapid and pronounced damage during the latent period (1 to 5 d). Subsequently, the firing characteristics and theta oscillations were impaired. In the chronic period (>10 d), the performance in the novel object experiment deteriorated. In conclusion, our study demonstrates the detrimental effect on spatial representations and electrophysiological properties of MEC neurons in the epileptic latency, suggesting the potential use of these changes as a "functional biomarker" for predicting cognitive impairment caused by epilepsy.