Effects of thalamic hemorrhagic lesions on explicit and implicit learning during the acquisition and retrieval phases in an animal model of central post-stroke pain.
Hemorrhagic stroke has many symptoms, including central pain, learning and memory impairments, motor deficits, language problems, emotional disturbances, and social maladjustment. Lesions of the ventral basal complex (VBC) of the thalamus elicit thermal and mechanical hyperalgesia, forming an animal model of central post-stroke pain (CPSP). However, no research has yet examined the involvement of learning and memory in CPSP using an animal model. The present study examined whether VBC lesions affect motor function, conditioned place preference (CPP; implicit memory), and spatial learning (explicit memory) in the acquisition and retrieval phases. The results showed that rats with VBC lesions exhibited thermal hyperalgesia in the acquisition and retrieval phases, indicating that these lesions can induce CPSP. During these phases, the rats with VBC lesions exhibited enhanced (morphine-induced) CPP learning. These lesions did not affect the rats' total distance travelled, time spent, or velocity in the spatial learning tasks. The lesions also did not affect motor function in the rotarod task. Altogether, VBC lesions resulted in CPSP and facilitated CPP (implicit memory). However, the lesions did not affect spatial learning (explicit memory) or motor function. The relationship between CPSP and learning and memory is important for patients who suffer from such central pain. The implications of the present study may provide insights into helping reduce CPSP and its associated symptoms.
Department of Psychology, Fo Guang University, Yilan County 26247, Taiwan.
Cheng Chung
CC
Wang
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Hsi-Chien
HC
Shih
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Bai Chuang
BC
Shyu
Department of Psychology, Fo Guang University, Yilan County 26247, Taiwan. Electronic address: chweihuang@mail.fgu.edu.tw.
Andrew Chih Wei
AC
Huang
D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant / Q000502:physiology; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000503:physiopathology; D020300:Intracranial Hemorrhages / Q000209:etiology* / Q000473:pathology; D008297:Male; D008569:Memory Disorders / Q000209:etiology*; D011939:Mental Recall / Q000502:physiology*; D010146:Pain / Q000209:etiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D045442:Rotarod Performance Test; D065853:Spatial Learning / Q000502:physiology*; D020521:Stroke / Q000150:complications*; D013788:Thalamus / Q000503:physiopathology*; D013997:Time Factors
Central post-stroke pain; Conditioned place preference; Morris water maze; Motor function; Spatial learning; Ventrobasal complex nuclei of the thalamus