ABSTRACT
BACKGROUND: Temporal cortex is related to human and animal's learning and memory capability, it not only accepts the casting fibers of auditory sense, but also closely connects with many brain areas where are related to spatial cognition.OBJECTIVE: To observe the improving effect of thrombolytic capsule on spatial cognitive capability of rats with lateral temporal cortical infarction DESIGN: Completely randomized controlled study SETTING: Department of Neurology, the 175th Hospital of Chinese PLA;Department of Neurology, General Hospital of Chinese PLA; Institute of Psychology of Chinese Academy of Science MATERIALS: This experiment was carried out at Brain Function Laboratory of Institute of Psychology of Chinese Academy of Science from August 1998 to February 1999, 28 SD rats were randomly divided into 3 groups,namely brain stroke group with 10 rats, treatment group with 10 rats and sham operation group with 8 rats.METHODS: Brain infarction model was established on SD rats by using three-dimensional directional photochemistry induction. Rats were anaesthetized with hydrochloride and intravenously injected of rose pink solution in dosage of 20 mg/kg from tail vein. Then incision was made on the left temporal scalp to expose temporal bone, cold photosource with the guidance of optical fiber was used for directional illumination for 20 minutes in area of 2 mm2. Twenty minutes later, rats in treatment group were given intraperitoneal injection of thrombolytic capsule physiological saline of 40 g/L in dosage of 200 mg/kg, which replaced by the same volume of physiological saline in brain stroke group. Rats in sham-operation group received the same operative lamination and injected with the same volume of physiological saline from tail vein and intraperitoneal cavity.MAIN OUTCOME MEASURES: Achievement of Morris water labyrinth(edge type scored 1, randomize type of 2, trend type of 3 and straight-line type of 4).age response time: it was shortened in treatment group and sham operation group than brain infarction group [ on 1st day: 58,50,65 s; 2nd day: 24,27,46 s; 3rd day: 14,17,20 s; 4th day: 11,9,15 s, (P ＜ 0.01 )], but it was similar ing strategy grades: on the 1st day, scores were slightly higher in treatment group and sham operation group than infarction group, but were instable (F=1.167, P ＞ 0.05). On the 2nd day, it was higher in sham operation group than brain stroke group[2.9,2.3, (F=5.5 ,P ＜ 0.05)], but it was similar between treatment group and infarction group[2.6,2.3 scores, (F=3.34,P ＞ 0.05)]. on the 3rd and 4th day, it was higher in treatment group than infarction group [ 3.5,2.7 minutes; 3.7,3.3 minutes, (F=8.92, 14, P ＞ 0.05)]and similar between treatment group and sham operation group(P ＞ 0.05).CONCLUSION: Rat response time was reduced by thrombolytic capsule during the early time of cerebral infarction, changing searching tactics gradually from randomized and edge type to tendency type and straight line type, suggesting thrombolytic capsule can improve the post-ischemia cognitive function, raise training record of cerebral infarctional rats.
ABSTRACT
Objective To explore the role of the prefrontal cortex in semantic encoding of unrelated word pairs by using functional near-infrared spectroscopy (fNIRS). Method Forty-eight subjects were presented unrelated pairs of Chinese words under both the nonsemantic and semantic encoding conditions. Under the nonsemantic condition, subjects judged whether the two words had similar orthographic structures; under the semantic condition, they generated a sentence involving the presented word pairs. The changes of regional blood volume associated with the cognitive tasks were measured by using fNIRS equipment which was a continuous optical imager. Result The regions that corresponded to the prefrontal regions showed greater activation under semantic than nonsemantic condition in both left and right hemispheres, although the extent of the activation was larger in the left than right prefrontal regions. This result was consistent with other neuroimaging studies on unrelated word pairs processing, but did not conform to the strict interpretations of the hemispheric encoding/retrieval asymmetry model (HERA). Conclusion This study suggests that material specificity is one of the important factors to influence hemispheric asymmetry in memory encoding. When associations between items are required, right prefrontal regions participate in the encoding processing as well. It also indicates that fNIRS imaging is a viable method of investigating higher level cognitive processing such as memory.
ABSTRACT
Objective To investigate the left prefrontal lobe activation during semantic and non-semantic encoding tasks with functional near-infrared imaging (fNIRI) technique. Method 22 healthy subjects were assigned semantic encoding and non-semantic encoding tasks. During semantic encoding tasks, subjects were asked to make a meaningful sentence including two unrelated Chinese word pairs, while during non-semantic encoding task they were asked to judge whether the two Chinese word pairs had the same morphological structure or not. Light intensity of two wavelengths (760 nm and 850 nm) diffused through skull and left prefrontal lobe were real-time recorded and used to reconstruct the brain activation image during the experiment. Result With the fNIRI, significant activations were observed in the left inferior prefrontal cortex (Brodmann' areas 45 and 47) during the two tasks, but the evoked activations were more significant for semantic than non-semantic task. These observations were consistent with the results reported by others with functional megnetic resonance imaging(fMRI) and positron-emission tomographyPET.Conclusion The results suggest that fNIRI provides an important, non-invasive way to map the prefrontal activation during cognitive tasks.