Memory deficits in Alzheimer's patients: A comprehensive review

Despite considerable experimental work on Alzheimer's disease (AD), the underlying cognitive mechanisms as well as the precise localization of neuropathological changes critical for memory loss remains undefined. A review of the neuropsychological literature on long-term memory deficits in AD patients suggests that AD patients display (a) a pervasive deficit of explicit memory, (b) a partial deficiency of implicit memory for verbal and visuoperceptual material (as measured by repetition priming procedures), and (c) a substantial sparing of implicit memory for visuomotor skills. The explicit memory loss is likely a result of encoding as well as consolidation difficulties. A faulty lexical-semantic knowledge structure appears responsible for deficient repetition priming effects. Since neuropathological changes diffusely affect the brain of AD patients, establishing a clear relationship between localization of cerebral lesions and memory deficits is particularly difficult. Nevertheless, data suggest that extensive involvement of the hippocampal-amygdala complex plays a major role in explicit memory loss. Damage to associative cortical areas likely is involved in repetition priming deficits. The relative integrity of primary motor and sensory cortical areas and of the basal ganglia likely subsume, by contrast, the normal learning of visuomotor skills.     

Impaired semantic memory during acute transient global amnesia

As a clinical model of hippocampal dysfunction, transient global amnesia (TGA) causes reversible memory disturbance. While episodic memory deficits in TGA patients have been extensively described, data regarding semantic memory involvement are sparse and contradictory. We report impaired semantic fluency performance in 16 patients with hippocampal lesions on MRI during acute TGA compared to their performance one day later and to that of 20 healthy subjects. Our findings support the involvement of the hippocampus in semantic retrieval.     

Using cumulative-recall curves to assess the extent of relational and item-specific processing

Although distinguishing between item-specific and relational information has proved to be a useful approach for understanding a variety of important memory phenomena, finding measurement tools for assessing the amount and type of information processed has proven difficult. Using the repeated-testing procedure, Burns (1993) demonstrated that item gains (the recall of items on a later test that were not recalled on earlier tests) and item losses (the forgetting of items on a later test that were recalled on earlier tests) reflected differences in amount of item-specific and relational information processed, respectively. Although several researchers have begun to use the measures with apparent success, the present research demonstrates that the accuracy of the item-gain measure is largely dependent on the rather arbitrary choice of recall-test length. We also show that a related but alternative measure, analysis of cumulative-recall curves, avoids some of the shortcomings of the item gain and loss measures. Moreover, we provide evidence for the generality of the cumulative-recall approach by demonstrating its effectiveness in mixed-list designs.     

Childhood amnesia: Empirical evidence for a two-stage phenomenon

The term childhood amnesia refers to the inability of adults to remember events from their infancy and early childhood. If we plot the number of memories that adults can recall as a function of age during childhood, the number of memories reported increases gradually as a function of age. Typically, this finding has been used to argue that gradual changes in memory development contribute to a gradual decline in childhood amnesia during the preschool period. Alternatively, it is possible that pooling data across participants has obscured more abrupt, stage-like changes in the remission of childhood amnesia. In the present study we examined the number and distribution of childhood memories for individual participants. Six adults were repeatedly interviewed about their childhood memories. We found that the distribution of adults' early childhood memories may be less continuous than pooled data suggest. This finding has important implications for current explanations of childhood amnesia.     

Phenomenology of autobiographical memories: The Memory Experiences Questionnaire

The phenomenology of autobiographical memories varies on a number of dimensions: some memories are vivid and others dim; some are emotionally intense and others lack emotional content. The present research sought to develop a psychometrically-sound scale to assess the entire range of dimensions on which autobiographical memories differ. We reviewed the literature on memory experiences and identified 10 relevant dimensions: Vividness, Coherence, Accessibility, Time Perspective, Sensory Details, Visual Perspective, Emotional Intensity, Sharing, Distancing, and Valence. We constructed a comprehensive item pool to assess these dimensions and, using data from several large samples (Ns=941; 510; 212), we showed that: (a) all 10 scales had adequate reliability (median alpha=.87; range=.72 to .97), (b) the 10-factor structure provided a good fit to the data, and (c) gender, personality, and memory recency had theoretically meaningful relations with the 10 scales. For example, gender and ethnicity differences in phenomenology were mediated by memory content, and early and recent memories had distinct phenomenologies. The discussion focuses on the theoretical and practical utility of the 10 scales.     

The onset of childhood amnesia in childhood: A prospective investigation of the course and determinants of forgetting of early-life events

The present research was an examination of the onset of childhood amnesia and how it relates to maternal narrative style, an important determinant of autobiographical memory development. Children and their mothers discussed unique events when the children were 3 years of age. Different subgroups of children were tested for recall of the events at ages 5, 6, 7, 8, and 9 years. At the later session they were interviewed by an experimenter about the events discussed 2 to 6 years previously with their mothers (early-life events). Children aged 5, 6, and 7 remembered 60% or more of the early-life events. In contrast, children aged 8 and 9 years remembered fewer than 40% of the early-life events. Overall maternal narrative style predicted children's contributions to mother–child conversations at age 3 years; it did not have cross-lagged relations to memory for early-life events at ages 5 to 9 years. Maternal deflections of the conversational turn to the child predicted the amount of information children later reported about the early-life events. The findings have implications for our understanding of the onset of childhood amnesia and the achievement of an adult-like distribution of memories in the school years. They highlight the importance of forgetting processes in explanations of the amnesia.     

儿童汉字练习:纸笔手写与键盘拼音输入的效果比较

在学校情境下,采用纸笔手写和键盘拼音输入练习汉字的实验任务,比较了75名小学六年级儿童在两种练习方式下的汉字学习及复习效果,并进行了保持效果的追踪。结果发现,纸笔手写和键盘拼音输入对儿童的汉字复习具有同等积极作用,在再认选择和回忆书写上效果均相当;对儿童的汉字学习积极作用不一致:在再认选择上两者积极效果相当,但在回忆书写上,手写明显优于拼音输入。另外,经纸笔手写和键盘拼音输入复习和学习的汉字,其记忆保持随时间变化的趋势一致。以上结果说明了对具有书面语言经验的儿童,拼音输入与手写都有助于形成和巩固汉字在心理词典中的义音形联结,但手写动作更有利于汉字从正字法代码向书写动作程序的转换;"提笔忘字"现象可能是正字法遗忘的结果,并非由使用拼音输入法造成。     

Predicting remembering and forgetting of autobiographical memories in children and adults: a 4-year prospective study

Preservation and loss to forgetting of autobiographical memories is a focus in both the adult and developmental literatures. In both, there are comparative arguments regarding rates of forgetting. Children are assumed to forget autobiographical memories more rapidly than adults, and younger children are assumed to forget more rapidly than older children. Yet few studies can directly inform these comparisons: few feature children and adults, and few prospectively track the survival of specific autobiographical memories over time. In a 4-year prospective study, we obtained autobiographical memories from children 4, 6, and 8 years, and adults. We tested recall of different subsets of the events after 1, 2, and 3 years. Accelerated rates of forgetting were apparent among all child groups relative to adults; within the child groups, 4- and 6-year-olds had accelerated forgetting relative to 8-year-olds. The differences were especially pronounced in open-ended recall. The thematic coherence of initial memory reports also was a significant predictor of the survival of specific memories. The pattern of findings is consistent with suggestions that the adult distribution of autobiographical memories is achieved as the quality of memory traces increases (here measured by thematic coherence) and the rate of forgetting decreases.     

Preserved re-experience of discrete emotions: Amnesia and executive function

Amnesic patients can re-experience emotions elicited by forgotten events, suggesting that brain systems for episodic and emotional memory are independent. However, the range of such emotional memories remains under-investigated (most studies employing just positive–negative emotion dyads), and executive function may also play a role in the re-experience of emotions. This is the first investigation of the intensity of the emotional re-experience of a range of discrete emotions (anger, fear, sadness, and happiness) for a group of amnesic patients. Twenty Korsakoff syndrome (KS) patients and 20 neurologically normal controls listened to four novel emotional vignettes selectively eliciting the four basic emotions. Emotional experience was measured using pen-and-paper Visual Analogue Mood Scales and episodic memory using verbal recollections. After 30 min, the recollection of stories was severely impaired for the patient group, but the emotional re-experience was no different from that of controls. Notably, there was no relationship between episodic recall and the intensity of the four emotions, such that even profoundly amnesic patients reported moderate levels of the target emotion. Exploratory analyses revealed negative correlations between the intensity of basic emotions and executive functions (e.g., cognitive flexibility and response inhibition) for controls but not patients. The results suggest that discrete emotions can be re-experienced independently of episodic memory, and that the re-experience of certain discrete emotions appears to be dampened by executive control. KS patients with absent or mild cognitive symptoms should benefit from emotion-regulation interventions aimed at reducing the recognized affective burden associated with their episodic memory deficit.