Levels of processing with free and cued recall and unilateral temporal lobe epilepsy

This study investigates the role of the temporal lobes in levels-of-processing tasks (phonetic and semantic encoding) according to the nature of recall tasks (free and cued recall). These tasks were administered to 48 patients with unilateral temporal epilepsy (right "RTLE"=24; left "LTLE"=24) and a normal group (n=24). The results indicated that LTLE patients were impaired for semantic processing (free and cued recall) and for phonetic processing (free and cued recall), while for RTLE patients deficits appeared in free recall with semantic processing. It is suggested that the left temporal lobe is involved in all aspects of verbal memory, and that the right temporal lobe is specialized in semantic processing. Moreover, our data seem to indicate that RTLE patients present a retrieval processing impairment (semantic condition), whereas the LTLE group is characterized by encoding difficulties in the phonetic and semantic condition.     

Memory and executive function impairments after frontal or posterior cortex lesions

Free recall and recognition, memory for temporal order, spatial memory and prospective memory were assessed in patients with frontal lobe lesions, patients with posterior cortex lesions and control subjects. Both patient groups showed equivalent memory deficits relative to control subjects on a range of free recall and recognition tasks, on memory for temporal order and on a prospective memory task. The patient groups also performed equivalently on the spatial memory task although only patients with frontal lobe lesions were significantly impaired. However, the patients with frontal lobe lesions showed an increased false alarm rate and made more intrusion errors relative not only to the control subjects, but also to the patients with poster or cortex lesions. These memory problems are discussed in relation to deficits in executive function and basic memory processes.     

Effects of level of retrieval success on recall-related frontal and medial temporal lobe activations

Brain dedicated single photon emission computed tomography (SPECT) was used to compare the neuroactivation produced by the cued recall of response words in a set of studied word pairs with that produced by the cued retrieval of words semantically related to unstudied stimulus words. Six of the 12 subjects scanned were extensively trained so as to have good memory of the studied pairs and the remaining six were minimally trained so as to have poor memory. When comparing episodic with semantic retrieval, the well-trained subjects showed significant left medial temporal lobe activation, which was also significantly greater than that shown by the poorly trained subjects, who failed to show significant medial temporal lobe activation. In contrast, the poorly trained subjects showed significant bilateral frontal lobe activation, which was significantly greater than that shown by the well-trained subjects who failed to show significant frontal lobe activation. The frontal activations occurred mainly in the dorsolateral region, but extended into the ventrolateral and, to a lesser extent, the frontal polar regions. It is argued that whereas the medial temporal lobe activation increased as the proportion of response words successfully recalled increased, the bilateral frontal lobe activation increased in proportion to retrieval effort, which was greater when learning had been less good.     

Discrimination of Facial Identity and Facial Affect by Temporal and Frontal Lobectomy Patients

The purpose of this study was to determine the extent to which lobectomy affects ability to discriminate facial identity or facial expression. Fifteen right temporal, 15 left temporal, 5 right frontal, and 4 left frontal lobectomy patients, pair-matched for age, sex, and education to normal control subjects, participated in this study. Tasks included a Facial Identity Matching Task and a Facial Affect Matching task. The lobectomized patients as a whole were significantly impaired on both tasks (22% decrement in performance). The patients made twice as many errors resulting from perseveration of response-set of the first condition (identity or emotion matching) into the second condition. The site of lobectomy did not influence general performance on any one task or selective performance on any subset of affective categories. It was concluded that all four brain regions play a significant and equal role in face processing, and that circuits more specifically dedicated to visual face processing, which are responsible for hemispheric dominance affects and affect/identity dissociations, are probably located more posteriorly in the brain. Finally, it was concluded that perseveration of acquired habit may, under specific conditions, characterize temporal lobe dysfunction just as much as frontal lobe dysfunction.     

Dissociations among memory measures in memory-impaired subjects: Evidence for a processing account of memory

Deficits in conceptual transfer on both implicit and explicit memory tests were obtained for memory-impaired temporal lobe epileptic (TLE) subjects in three studies. In Experiment 1, in which a generate-read paradigm was employed, memory-impaired TLEs failed to show normal generation effects on conceptually driven tests of semantic cued recall and general knowledge questions, although their data-driven memory as measured by word-fragment completion and graphemic cued recall tasks was normal. In Experiment 2, memory-impaired patients having left temporal lobe seizure foci were tested on these four tasks and compared with nonimpaired TLEs having right temporal foci. The left TLEs showed deficits on conceptually driven tasks and normal memory for data-driven tests. These findings were extended in Experiment 3, in which left TLE patients failed to show any benefit from blocked study, as compared with random study, on category production and semantic cued-recall tests, although right TLEs and normal controls showed blocking effects on both tasks. These findings may be accommodated by a processing framework of memory in which memory-impaired patients are characterized as having deficits in conceptual, but not in data-driven, processing capabilities.     

Memory in autistic spectrum disorder

Behavioral evidence concerning memory in forms of high-functioning autism (HFA) and in moderately low-functioning autism (M-LFA) is reviewed and compared. Findings on M-LFA are sparse. However, it is provisionally concluded that memory profiles in HFA and M-LFA (relative to ability-matched controls) are similar but that declarative memory impairments are more extensive in M-LFA than in HFA. Specifically, both groups have diminished memory for emotion- or person-related stimuli. Regarding memory for nonsocial stimuli, both groups probably have mental-age-appropriate nondeclarative memory, and within declarative memory, both groups have mental-age-appropriate immediate free recall of within-span or supraspan lists of unrelated items, as well as cued recall and paired associate learning. By contrast, recognition is largely unimpaired in HFA but moderately impaired in M-LFA, and free recall of meaningful or structured stimuli is moderately impaired in HFA but more severely impaired in M-LFA. Theoretical explanations of data on declarative memory in HFA identify problems in the integrative processing, or the consolidation and storage, of complex stimuli or a specific problem of recollection. Proposed neural substrates include the following: disconnectivity of primary sensory and association areas; dysfunctions of medial prefrontal cortex, hippocampus, or posterior parietal lobe; or combinations of these associated with neural disconnectivity. Hypothetically, perirhinal dysfunction might explain the more extensive declarative memory impairments in M-LFA. Foreseeable consequences of uneven memory abilities in HFA and M-LFA are outlined, including possible effects on language and learning in M-LFA. Finally, priorities for future research are identified, highlighting the urgent need for research on memory in lower functioning individuals.     

Cue utilization following different forms of encoding in mildly, moderately, and severely demented patients with Alzheimer's disease

The ability of patients with Alzheimer's disease (AD) to utilize semantic category cues in order to improve memory performance was examined. Categorizable lists of words or objects were presented under five different encoding conditions: (a) nouns, (b) objects, (c) objects with a semantic orienting question, (d) objects with self-generated motoric acts, and (e) objects with experimenter-instructed motoric acts. Subjects were asked to memorize the items for a free recall test, and were subsequently provided with the category names in a cued recall test. Mildly, moderately, and severely demented AD patients, and a group of normal older adults participated in the study. Results showed that normal older adults and mildly demented AD subjects were able to utilize cues to improve memory performance in all conditions. Moderately demented patients utilized cues in all conditions except in the verbal condition (condition [a]), whereas severely demented patients utilized cues only in the motoric condition (condition [e]). These results suggest that the ability to utilize category cues following a motoric encoding is preserved later in AD than the ability to utilize cues after a semantic encoding.     

Effects of aging and IQ on item and associative memory

The effects of aging and IQ on performance were examined in 4 memory tasks: item recognition, associative recognition, cued recall, and free recall. For item and associative recognition, accuracy and the response time (RT) distributions for correct and error responses were explained by Ratcliff's (1978) diffusion model at the level of individual participants. The values of the components of processing identified by the model for the recognition tasks, as well as accuracy for cued and free recall, were compared across levels of IQ (ranging from 85 to 140) and age (college age, 60-74 years old, and 75-90 years old). IQ had large effects on drift rate in recognition and recall performance, except for the oldest participants with some measures near floor. Drift rates in the recognition tasks, accuracy in recall, and IQ all correlated strongly. However, there was a small decline in drift rates for item recognition and a large decline for associative recognition and cued recall accuracy (70%). In contrast, there were large effects of age on boundary separation and nondecision time (which correlated across tasks) but small effects of IQ. The implications of these results for single- and dual-process models of item recognition are discussed, and it is concluded that models that deal with both RTs and accuracy are subject to many more constraints than are models that deal with only one of these measures. Overall, the results of the study show a complicated but interpretable pattern of interactions that present important targets for modeling.     

额叶参与对新异联系的启动效应——来自脑损伤病人的证据

对新异联系的启动效应是内隐记忆的一种形式,又称联想启动。采用知觉辨认任务,探讨额叶损伤与联想启动的关系。25例额叶损伤病人及18例匹配的正常被试参与实验。结果表明,额叶受损病人辨认旧词对与重组词对的正确率没有明显差别;而且,轻度记忆损伤的额叶病人再认成绩正常,但联想启动值低于对照组,内隐记忆和外显数、坚持性反应数和语词流畅性等有中度相关。这些结果提示,额叶不仅与情节记忆、工作记忆等外显记忆有关,也参与了以非相关词对为材料的联想启动。     

Children's cued recall: Developmental differences in retrieval operations

Second and fifth grade children were aurally presented a study list containing eight target items plus primacy and recency buffers, followed first by free recall, then by cued recall for items not produced in free recall. Two additional buffer items were used at Grade 5 in an effort to equate the two age groups in free recall of targets. The cues were either of high or of moderate associative strength, and equal for the two age groups. Free recall of targets did not differ with age, suggesting equivalent storage of targets. At Grade 2 the cued recall level matched expectations based on a simple associative account of cuing effects. However, cued recall at Grade 5 was much higher than the normative association values, implicating strategic retrieval operations, the possible nature of which was discussed.     

The information that amnesic patients do not forget

The performance of three kinds of amnesic patients and control subjects was assessed using four methods for testing memory: free recall, recognition, cued recall, and word completion. Whereas amnesic patients were impaired on free recall, recognition, and cued recall, they were normal on word completion. Moreover, performance on the word-completion test declined at a normal rate reaching chance after about 120 min. The word-completion test resembled the cued-recall test in that the initial letters of previously presented words were given as cues. It differed from cued recall only in the instructions, which directed subjects away from the memory aspects of the test and asked them to complete each three-letter cue with the first word that came to mind. The present results offer an explanation of conflicting findings that have been obtained with amnesic patients on tests of the cued-recall type. The results are considered in terms of a process (activation or procedural learning), which is spared in amnesia and not dependent on the integrity of the damaged brain regions.     

逆行性遗忘、额叶与远期记忆的组织

通过对一例严重记忆障碍合并额叶损伤病人的逆行性遗忘的分析,对远期记忆的组织特点进行了探讨。被试的额叶功能受损较为明显。除顺行性遗忘外,患者的逆行性遗忘也较为严重。对病人进行的逆行性遗忘检测包括：著名人物测验、著名事件、一般知识测验和自传性记忆测验等。被试对著名人物、著名事件的回忆和再认成绩、以及有关个人的情节和语义记忆成绩均较低,但没有典型的随时间下降的趋势,而是呈平直斜率;患者儿童期的自传性记忆和公众事件记忆也受损。这两个特点均与内侧颞叶一间脑系统损伤的特点不同,提示额叶参与了远期记忆的提取等过程。     

Attention deficit hyperactivity disorder and the frontal lobe syndrome.

The usefulness of frontal lobe (FL) dysfunction as a conceptual model for Attention Deficit Hyperactivity Disorder (ADHD) was investigated. Twenty-four ADHD and 24 normal control (NC) children were tested using two batteries of tasks. The first was sensitive to FL deficits in motor control and problem solving skills. The second consisted of memory tasks sensitive to temporal lobe dysfunction. ADHD children differed significantly from NCs on measures of FL function, but not on tests of temporal lobe functions. Where norms were available for normal children on the same FL tests, ADHDs performed like 6- to 7-year-olds, despite their mean age of 10 years and minimum age of 8 years. The differential performance of ADHDs on tasks sensitive to FL and temporal lobe dysfunction supports the hypothesis that ADHD deficits are analogous to FL dysfunction and demonstrates that the children's deficits do not reflect generalized cognitive impairment.     

Do novel associative word stem completion and cued recall share the same memory retrieval processes?

The aim of this study was to determine whether word stem completion for novel associations between cue and target words was mediated by automatic unconscious memory processes or effortful memory processes under conscious control. This was done by applying full and divided attention conditions at test to stem completion, cued recall, and recognition, and by administering a questionnaire that probed the memory strategies used by subjects during the completion test. Divided attention had no effect on stem completion performance, but did reduce associative cued recall. Recognition performance was weakened overall by divided attention, but the associative effect was similar under both attention conditions. This suggested that novel associative word stem completion was mediated by automatic retrieval processes. However, the results of the questionnaire indicated that only subjects who attempted to remember the words from the study phase during the completion task showed any novel associative effect. It is concluded that novel association word stem completion and cued recall share automatic retrieval processes, which nevertheless give rise to the experience of remembering.     

The time course of episodic associative retrieval: Electrophysiological correlates of cued recall of unimodal and crossmodal pair-associate learning

Little is known about the time course of processes supporting episodic cued recall. To examine these processes, we recorded event-related scalp electrical potentials during episodic cued recall following pair-associate learning of unimodal object-picture pairs and crossmodal object-picture and sound pairs. Successful cued recall of unimodal associates was characterized by markedly early scalp potential differences over frontal areas, while cued recall of both unimodal and crossmodal associates were reflected by subsequent differences recorded over frontal and parietal areas. Notably, unimodal cued recall success divergences over frontal areas were apparent in a time window generally assumed to reflect the operation of familiarity but not recollection processes, raising the possibility that retrieval success effects in that temporal window may reflect additional mnemonic processes beyond familiarity. Furthermore, parietal scalp potential recall success differences, which did not distinguish between crossmodal and unimodal tasks, seemingly support attentional or buffer accounts of posterior parietal mnemonic function but appear to constrain signal accumulation, expectation, or representational accounts.     

Age differences in veridical and false recall are not inevitable: The role of frontal lobe function

The relationship of neuropsychological measures of frontal lobe function to age differences in false recall was assessed using the Deese/Roediger-McDermott associative false memory paradigm (Deese, 1959; Roediger & McDermott, 1995). As other studies have found, older adults were less likely to correctly recall studied items and more likely to falsely recall highly related but nonpresented items than were younger adults. When older adults were divided based on a composite measure of frontal lobe functioning, this age difference was found only for low frontal lobe functioning individuals. High frontal lobe functioning older adults and young adults had equivalent levels of false recall, as well as equivalent levels of veridical recall. These results suggest that age differences in memory may be due to declines in frontal lobe function. More important, our findings indicate that declines in veridical recall and increases in false recall are not an inevitable consequence of aging.     

Dichotic listening,executive functions and grey matter cortical volume in patients with schizophrenia and healthy controls

Schizophrenia is characterized by cognitive impairment, especially in relation to executive functions. Brain structural abnormalities are also often seen in schizophrenia although little is known of the relationship between cognitive impairment and structural brain changes. Our aim was therefore to investigate this relationship further using MRI and a dichotic listening (DL) task with simple speech sounds and with instructions to focus attention and report only from the left or right ear stimulus. When instructed to focus attention on the left ear syllable a cognitive conflict is induced requiring the allocation of executive resources to be resolved. Grey matter (GM) volume was measured with MRI from four volumes of interests (VOIs), left and right frontal and temporal cortex, respectively, and correlated with DL performance. The results showed significant differences between the groups in their ability to focus attention on and report the left ear stimulus, which was accompanied by reduced GM volume in the left frontal and right temporal lobe VOIs. There was also a significant positive correlation between left frontal GM volume and performance on the DL task, for the groups combined. The results did not support a conclusion that an impairment in cognitive function in schizophrenia was driven by an corresponding impairment in brain structure, since there were no significant correlations when the groups were analyzed separately. It is however concluded that patients with schizophrenia are impaired in executive functions and that they also show reduced GM volumes in left frontal and right temporal lobe areas, compared to healthy controls.     

Verbal and Nonverbal Emotional Memory Following Unilateral Amygdala Damage

The amygdala is involved in the normal facilitation of memory by emotion, but the separate contributions of the left and right amygdala to memory for verbal or nonverbal emotional material have not been investigated. Fourteen patients with damage to the medial temporal lobe including the amygdala (seven left, seven right), 18 brain-damaged, and 36 normal controls were exposed to emotional and neutral pictures accompanied by verbal narratives. Memory for both narratives and pictures was assessed with a free recall test 24 h later. Subjects with left amygdala damage failed to show the normally robust enhancement of memory for verbal and nonverbal emotional stimuli. The group with right amygdala damage showed the normal pattern of facilitation of memory by emotion for both verbal and nonverbal stimuli despite an overall reduction in memory performance. Furthermore, subjects with left amygdala damage were disproportionately impaired on memory for emotional narratives as compared with memory for emotional pictures. The latter finding offers partial support for a lateralized and material-specific pattern of the amygdala's contribution to emotional memory.     

Impaired acquisition of temporal information in retrosplenial amnesia

In this paper we describe the performance of an amnesic with a left retrosplenial lesion on three memory tasks assessing his ability to judge when a previously learned event had occurred. This patient was dramatically impaired in acquiring temporal information about new stimuli, and this defect could not be attributed to recognition failures or to frontal lobe dysfunction. In contrast to his impaired acquisition of temporal information, he had no difficulty judging the temporal order of remote historical events. The pattern of performance displayed by this patient suggests a specific defect in "time-tagging" of new incoming information.     

Diagnosing criterion-level effects on memory: what aspects of memory are enhanced by repeated retrieval?

Previous research has shown that increasing the criterion level (i.e., the number of times an item must be correctly retrieved during practice) improves subsequent memory, but which specific components of memory does increased criterion level enhance? In two experiments, we examined the extent to which the criterion level affects associative memory, target memory, and cue memory. Participants studied Lithuanian-English word pairs via cued recall with restudy until items were correctly recalled one to five times. In Experiment 1, participants took one of four recall tests and one of three recognition tests after a 2-day delay. In Experiment 2, participants took only recognition tests after a 1-week delay. In both experiments, increasing the criterion level enhanced associative memory, as indicated by enhanced performance on forward and backward cued-recall tests and on tests of associative recognition. An increased criterion level also improved target memory, as indicated by enhanced free recall and recognition of targets, and improved cue memory, as indicated by enhanced free recall and recognition of cues.