Neural plasticity in vivo: opioid sensitivity of memory develops gradually after a septal lesion

Neuronal plasticity can manifest itself in alterations in the sensitivity of memory to the effects of drugs. After the production of a brain lesion, the memory processing of a passive-avoidance task in mice gradually becomes sensitive to the effect of morphine, i.e., an improvement in retention performance is seen after 6 weeks, but not after 1 or 2 weeks. The results presented demonstrate that, even if they lead to no discernible changes in behaviour, plastic processes can still be detected by means of behavioural tests.     

低强度超短波对小鼠体质及智力的影响

本实验探讨了低强度超短波对小鼠连续三代辐射,对学习、记忆、拉力、运动耐力和周围血象的影响。用81MHz,10～12V/m 的超短波进行辐射,每天辐射2小时,每周6天。结果表明:经过超短波辐射的各代小鼠与对照组相比,学习能力、记忆能力、拉力及运动耐力有明显的降低,且运动耐力有进行性降低的趋势,而经过辐射的三代小鼠红细胞、血红蛋白含量及白细胞数均明显增高,每个红细胞的血红蛋白含量则低于对照组。     

A longitudinal study of age-associated memory impairment

An 8-year longitudinal study of elderly people has provided data concerning age-associated impairment (AAMI). In 1985 a random sample of 146 persons aged 65 years or more, living in their own homes, were assessed using the Guild Memory Test the Mini–Mental State Examination (MMSE) and other ratings. After excluding 21% of the sample because they scored less than 24 on the MMSE, and another 34% who fulfilled other exclusion criteria, some 48% of the remainder (22% of the total sample) clearly fulfilled NIMH criteria for AAMI and a further 36% (16% of the total sample) were recorded as forgetful. The NIMH criteria are appropriate for certain research purposes but not in assessing prevalence of memory disorders. Follow–up interviews were conducted after 2, 4, 6 and 8 years. The mortality rate and development of dementia among those fulfilling criteria for AAMI appeared similar to the other non-demented groups of subjects; the mortality rate of those with MMSE scores below 24 was significantly higher. Guild test results at 2-yearly intervals showed considerable changes; half of those scoring least well who were retested showed improvement.     

The locus coeruleus, norepinephrine, and memory in newborns

Use of learned odor cues by newborn rats is critical for pup survival. Rat pups acquire approach responses to maternal odors through an associative conditioning mechanism. This learned behavioral response is accompanied by a modification of olfactory bulb neural response patterns to the learned odor. Both the behavioral and neural reponse changes involved and require norepinephrine release in the olfactory bulb. The source of this norepinephrine is the locus coeruleus. It is proposed that the unique response properties of the locus coeruleus during the early postnatal period in the rat may facilitate acquisition of these critical early memories.     

An integrative psychophysiological approach to brain hemisphere functions in schizophrenia

The present paper proposes a new psychophysiological approach to the genesis of positive and negative schizophrenic symptoms. According to this approach, the initial factor in schizophrenic disorders is a functional insufficiency of the right hemisphere which can be determined by early emotional experience in combination with subtle brain damage. This functional insufficiency causes (a) the inability to grasp and select information before its realization; and (b) the inability to produce a polysemantic context which is crucial for creativity, psychological defense, and the restoration of search activity, all of which determine psychophysiological adaptation to the environment. Right hemisphere insufficiency causes left hemisphere hyperactivity as an ineffective attempt to compensate for this functional deficiency. As a result, normal search activity is replaced by artificial search activity which is represented by “positive” symptoms, and which uses the predisposition of the left hemisphere's catecholamine system for its increased activity. The suggestion is made that cognitive impairment in schizophrenia (the inability to use appropriate previous information in relation to current perceptual input) is related to the competition between information processing which requires left hemisphere activity, and the formation of positive symptoms, also based on left hemisphere activity.     

Disinhibition of somatosensory evoked potential recovery in alcoholics

The pathogenesis of cognitive impairment in alcoholics remains unclear. Previous studies suggested that diffuse white matter atrophy is associated with cognitive impairment in alcoholics. To elucidate this issue, the present study evaluated alcoholics with cognitive impairment using the somatosensory evoked potential (SEP) recovery method, which is suitable for detecting subtle dysfunction at the cortical level. Subjects comprised 12 alcoholics with mild cognitive impairment [Mild group: Mini Mental State Examination Score (MMSE), ≥24; mean, 27.9 ± 1.6], 12 alcoholics with moderate to severe cognitive impairment (Moderate group: MMSE score, < 24; mean, 21.0 ± 2.5) and 12 normal subjects (Control group). SEP was recorded from the hand sensory area contralateral to the median nerve stimulated at the wrist. Single-pulse or paired-pulse stimuli at various interstimulus intervals (10–300 ms) were administered. Recovery functions of N9 (a peripheral nerve component), N20, N20-P25 and P25-N33 (cortical components) were studied. N20 recovery curves of both alcoholic groups were less suppressive than those of Controls, and P25-N33 recovery curves of the Moderate group were more excitatory than those of the Mild or Control groups. A disinhibited recovery pattern of N20 indicates subcortical dysfunction, and a disinhibited pattern of P25-N33 would be induced by cortical dysfunction. Therefore, subcortical dysfunction indicated by an abnormal N20 recovery pattern may contribute to the early cognitive impairment of alcoholics, whilst the cortical dysfunction indicated by an abnormal P25-N33 recovery pattern may contribute to the later cognitive impairment of alcoholics.     

认知矫正治疗前后慢性精神分裂症患者功能磁共振成像的对照研究

目的 探讨认知矫正治疗对精神分裂症患者工作记忆相关脑区活动的影响.方法 对10例病情稳定的慢性精神分裂症患者进行为期6个月的认知矫正治疗,分别于治疗前后进行韦克斯勒记忆量表(WMS)测查及功能磁共振成像(fMRI)测量.结果 (1)WMS测查:治疗后再认[(8.11±4.34)分]和再生[(10.22±3.35)分]以及Benton错误[(3.75±2.92)分]均较治疗前[分别为(5.78±2.95)分、(8.56±3.21)分和(8.00±6.28)分]改善,均P＜0.05.(2)fMRI:治疗前后的反应时和正确率比较,差异无统计学意义(P＞0.05).治疗后在高负荷条件下,背侧前额叶皮质(DLPFC)区域(Brodmann46区)的激活范围(x,y,z=-51,36,15;k=40,t=7.21)小于治疗前的激活范围(x,y,z=-48,24,24,k=154,t=12.72),治疗前后DLPFC区域激活(x,y,z=-24,36,18,k=12,t=3.75)的差异有统计学意义(P＜0.005);在低负荷条件下,治疗前后DLPFC区域激活的差异无统计学意义(P＞0.05).结论 认知矫正治疗能改善精神分裂症患者工作记忆相关脑区的活动.     

图片学习测验在识别老年人轻微认知功能损害中的作用

目的　分析图片学习测验在识别老年人轻微认知功能损害 (MCI)中的作用。方法　选择符合MCI诊断标准的老年人 4 8例与正常对照组 5 6名完成图片学习测验、简易智能状态检查、听觉词语学习测验及多种非记忆测验。结果　图片学习测验的 3个记忆指标 (图片短时记忆、延迟记忆和学习记忆 )在MCI与正常对照组之间有非常显著的差异。已经给出这三个图片记忆指标区分MCI与正常老年人的划界分、敏感性和特异性。结论　图片记忆操作简便、信度和效度好 ,可以作为临床医师筛选MCI的有效工具     

Effects of purine analogues on spontaneous alternation in mice

The Y-maze was used to examine the effects of purines acting at A₁ and A₂ adenosine receptors upon spontaneous alternation, a model of working memory, in mice. In support of previous work, scopolamine produced a loss of spontaneous alternation behaviour to the 0.5 chance level. The A₁ receptor selective agonist N6-cyclopentyladenosine (CPA) did not change spontaneous alternation behaviour alone, but it prevented the decrease of spontaneous alternation scores produced by scopolamine. The A₁ receptor selective antagonist 1,3-dipropyl-8-cyclopentylxanthine (CPX) blocked the effect of CPA in combination with scopolamine but had no effect alone. The A₂ receptor selective agonist (N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl]adenosine (DPMA), and the A₂ receptor selective antagonist 3,7-dimethyl-1-propargylxanthine (DMPX) had no effect of alternation behaviour alone and did not modify the effect of scopolamine. The results indicate the ability of A₁ but not A₂ receptor activation to modify working memory deficits induced by scopolamine, but suggest that endogenous adenosine does not normally participate in working memory processes.