Do age differences in odour memory depend on differences in verbal memory?

Studies of human odour memory have in most cases been obscured by the experimental designs utilised, in which verbal memory played a crucial role in the subjects' performance. Previously, attempts have been made to minimise verbal mediation in the assessment of odour memory by the use of incidental or implicit learning, which is how odours are learned in everyday life; it is still under debate whether this form of learning is age-dependent or not. In this experiment we make use of very uncommon odours and show that incidental learning of odours is as good in elderly people as in the young, whereas intentional learning is better in young people.     

Can postictal memory predict postoperative memory in patients with temporal lobe epilepsy?

We investigated the contribution of postictal memory testing for lateralizing the epileptic focus and predicting memory outcome after surgery for temporal lobe epilepsy (TLE). Forty‐five patients with TLE underwent interictal, postictal, and postoperative assessment of verbal and nonverbal memory. Surgery consisted of anterior temporal lobectomy (36), selective isolated amygdalohippocampectomy (6), or amygdalohippocampectomy coupled to lesionectomy (3). Postictal and postoperative but not interictal memory were significantly lower in left TLE than in right TLE. Nonverbal memory showed no significant difference in left TLE versus right TLE in all conditions. Postictal memory was significantly correlated with postoperative memory, but the effect disappeared when the lateralization of the focus was considered. Postictal verbal memory is a useful bedside tool that can help lateralize the epileptic focus. Larger studies are needed to further estimate its predictive value of the postoperative outcome.     

Panic disorder and memory: does panic disorder result from memory dysfunction?

It is proposed that patients with panic disorder have a defect in fear-relevant episodic memory, and their panic attacks arise from automaticity in recollecting fear-relevant emotional-autonomic cluster. The cluster as a component of fear appears to have been dissociated from cognitive structure (episodic or informative memory trace) or from "information structure". A special method was created for testing this hypothesis where 30 panic disorder patients, 12 healthy controls, and 32 patients with other psychiatric diagnoses were asked to recall and describe a fearful experience. None of the patients in the panic disorder group could recall any fearful event or episode in their past. All but one subject among healthy controls and all the subjects in the non-panic group could recall one or more fearful event or episode. Possible theoretical implications of these results are discussed in the context of some classical concepts.     

Delayed recognition memory in Parkinson's disease: a role for working memory?

Immediate and delayed recognition memory for words was examined in a sample of 16 non-demented patients with Parkinson's disease and 16 normal control participants of equivalent age and educational attainment. The patients, relative to control participants, had intact immediate but impaired delayed recognition memory performance. Patients were also impaired on tests of free and cued recall, working memory and a measure of psychomotor processing speed. Processing speed was a significant covariate for delayed recognition, free and cued recall and working memory performance, but not for immediate recognition performance. These results suggest that the same cognitive processes which support performance on tests of recall and working memory also support performance on tests of delayed recognition.     

Do memory complaints represent impaired memory performance in patients with major depressive disorder?

Memory complaints are found to be associated with depression. However, the question is, “How much these subjective complaints indicate objective memory impairments?” The aim of this study is to determine whether subjective memory complaints represent objective memory impairments and to establish the demographic and clinical characteristics of patients with major depressive disorder (MDD) and subjective memory complaints. Sixty‐four patients with MDD were assessed for objective memory performance through subtests of the Wechsler Memory Scale‐III. Memory complaints also were assessed in these patients with a structured interview. Thirty healthy controls were also included in the study to compare memory performance among groups. The Hamilton Rating Scale for Depression was used to measure the severity and characteristics of depression. Patients with MDD who had longer duration and earlier onset of depression reported more memory complaints. MDD patients with memory complaints had more hypochondriac concerns but not more depression severity compared with those without memory complaints. There was no relationship between subjective memory complaints and objective memory performance in MDD patients. Patients with MDD with and without memory complaints had lower scores on the Wechsler Memory Scale‐III than the control group. Subjective memory complaints are not a valid indictor of objective memory impairments, and the diagnostic value of self‐reported memory is being questioned in patients with MDD. The cognitive status of MDD patients should be assessed routinely, regardless of the patient awareness of his or her cognitive deficits. Depression and Anxiety, 2008. © 2007 Wiley‐Liss, Inc.     

The role of the hippocampus in long-term memory: is it memory store or comparator?

Several attempts have been made to reconcile a number of rival theories on the role of the hippocampus in long-term memory. Those attempts fail to explain the basic effects of the theories from the same point of view. We are reviewing the four major theories, and shall demonstrate, with the use of mathematical models of attention and memory, that only one theory is capable of reconciling all of them by explaining the basic effects of each theory in a unified fashion, without altogether sacrificing their individual contributions. The key issue here is whether or not a memory trace is ever stored in the hippocampus itself, and there is no reconciliation unless the answer to that question is that there is not. As a result of the reconciliation that we are proposing, there is a simple solution to several outstanding problems concerning the neurobiology of memory such as: consolidation and reconsolidation, persistency of long term memory, novelty detection, habituation, long-term potentiation, and the multifrequency oscillatory self-organization of the brain.     

Are memory traces localized or distributed?

Evidence supports the view that "memory traces" are formed in the hippocampus and in the cerebellum in classical conditioning of discrete behavioral responses (e.g. eyeblink conditioning). In the hippocampus, learning results in long-lasting increases in excitability of pyramidal neurons that appear to be localized to these neurons (i.e. changes in membrane properties and receptor function). However, these learning-altered pyramidal neurons are distributed widely throughout CA3 and CA1. Although it plays a key role in certain aspects of classical conditioning, the hippocampus is not necessary for learning and memory of the basic conditioned responses. The cerebellum and its associated brain stem circuitry, on the other hand, does appear to be essential (necessary and sufficient) for learning and memory of the conditioned response. Evidence to date is most consistent with a localized trace in the interpositus nucleus and multiple localized traces in cerebellar cortex, each involving relatively large ensembles of neurons. Perhaps "procedural" memory traces are relatively localized and "declarative" traces more widely distributed.     

How are memory complaints in functional memory disorder related to measures of affect, metamemory and cognition?

Objective

Memory complaints are a common finding in outpatients, especially in psychosomatic and neurological practice. In a substantial group of patients persistent memory complaints are found in the absence of abnormal neuropsychology. Different labels such as “functional memory complaint” have been suggested for this phenomenon. We characterise a group of patients with such memory complaints, which we termed functional memory disorder (FMD). The aim of the present study is to describe patients with FMD.

Methods

Thirty-nine patients with FMD were compared to 38 control subjects. Data were collected on the German version of the Rey Auditory Verbal Learning test and the Zahlenverbindungstest (cognitive speed), subscales of the Metamemory in Adulthood questionnaire (MIA), the Perceived Stress Questionnaire (PSQ), the Global Severity Index (GSI) of the Symptom Checklist, the Beck Depression Inventory (BDI), and other psychological questionnaire measures.

Results

We found significant group differences on all psychological questionnaire measures, with more pathological scores in the patient group. GSI and PSQ were the best predictors of memory self-efficacy. MIA-Memory Self-Efficacy (MSE), MIA-Achievement, and BDI were the best predictors of group membership (FMD vs. control group). When MSE was excluded, MIA-Achievement and BDI or GSI were the only predictors of group membership. Neuropsychological measures predicted neither MSE nor group membership.

Conclusions

Pathological scores on measures of metamemory, stress, and depression are typical of FMD. Low MSE and a high memory-related achievement motivation seem to be key features of FMD. Other important features are increased perceived stress, general psychosomatic complaint, and elevated depression scores. Neuropsychological test performance is not associated with FMD symptoms.     

Alzheimer’s disease and memory strength: Gradual decline of memory traces as a function of their strength

Objective: Episodic memory impairment is at the core of amnestic mild cognitive impairment (aMCI) and Alzheimer’s disease (AD). The origin of memory deficits may result either from an encoding deficit or from an accelerated decline of the memory trace. The present study explores these two hypotheses. Method: We used the delayed-matching-to sample 48 items (DMS-48) memory test in a group of controls, aMCI patients, and AD patients (n= 16 in each group). The DMS-48 offers an incidental learning phase followed by three forced-choice recognition tests at three-minute, one-hour, and one-week delays. Moreover, the forced-choice test distinguishes three kinds of couple items: abstract (meaningless), paired (two similar exemplars), and unique (two different objects) items. Results: As predicted by the accelerated forgetting hypothesis, patients showed a decrease in recognition performance over time. Controls also exhibited a similar decline in performance. As predicted by the encoding deficit hypothesis, abstract items were the most poorly recognized in AD, at both the three-minute and the one-week delays. In AD, recognition of the paired items also dropped after the one-hour delay, followed by unique items after a one-week delay. Patients with aMCI exhibited a performance that was similar to controls, except for abstract items, which dropped at the one-week delay. Conclusions: These results are discussed in light of a third hypothesis, the memory strength hypothesis, in order to better account for the progressive decline in memory performance as a function of the item type in AD.     

Does “thinking about thinking” interfere with memory? An experimental memory study in obsessive–compulsive disorder

Neuropsychological assessments of participants with obsessive–compulsive disorder (OCD) indicate impaired verbal memory if to be remembered material has to be organized. People with OCD also tend to focus their attention on their thoughts (heightened cognitive self-consciousness). We tested the hypothesis that cognitive self-consciousness causes verbal memory deficits by provoking a division of attention between study task and thoughts. Thirty-six participants with OCD, 36 matched healthy controls and 36 participants with major depressive disorder (MDD) learned under proactive interference in three study conditions: single-task condition, condition with heightened cognitive self-consciousness and condition with an external secondary task. Memory was impaired in the cognitive self-consciousness condition compared to both other conditions. Independent of condition, participants with OCD showed a reduced memory performance compared to healthy controls, but did not differ from participants with MDD. Our results are in line with the hypothesis that cognitive self-consciousness causes memory impairment.     

Any novelty in hippocampal formation and memory?

PURPOSE OF REVIEW: Novel events tend to attract attention and become more effectively encoded in memory than predictable events. The hippocampus and medial-temporal cortical regions, along with regions of the prefrontal cortex, have been associated with enhanced memory for novel events. This review provides an update on recent studies of hippocampal novelty responses in relation to memory. RECENT FINDINGS: Several different types of novelty have been studied. Stimulus novelty effects have been observed as reduced neural activity in the medial-temporal and prefrontal regions when the same stimulus is repeatedly presented. Contextual novelty effects, the detection of a stimulus or event in an unexpected context, is impaired in patients with hippocampal damage. Single-trial analyses of brain activity show that the hippocampus rapidly habituates to contextually novel situations. Associative novelty, the detection of new arrangements of familiar stimuli, has also been related to the medial-temporal regions. A division of labour among the medial-temporal regions has been proposed such that associative novelty selectively engages the hippocampus, whereas stimulus novelty is mediated by the perirhinal cortex. However, a simple account of when the hippocampus versus other medial-temporal cortical regions is recruited awaits further studies. Increased dopaminergic and cholinergic neurotransmission may account for enhanced memory encoding of novel events, and relate to structural neuronal changes. SUMMARY: Interindividual variability in the responsiveness of the hippocampal-novelty system may be genetically mediated, and personality factors can also play a role. A better understanding of such variability can have implications for interventions aimed at supporting memory and for the treatment of drug abuse.     

Avicenna’s pharmacological approach to memory enhancement

In recent decades, the number of patients with dementia has significantly risen. Current treatments for dementia are not curative and there still is place for development of medications. Throughout the ages, several medical disciplines have systematized and codified medical knowledge acquired throughout centuries of trial and error. Revisiting these disciplines might help in gaining insight for development of medications and other therapeutic strategies. The present study aims to show the possible benefits of an immanent understanding of the approach towards memory and dementias taken by humoral medical discourse in the Islamicate world. This study presents how brain function was theorized in the medieval Islamicate world. Afterwards, a brief history of the theory of the inner senses and of humoral medicine is briefly presented. Then the definition of memory and its localization within the brain as theorized in the framework of humoral medicine is closely studied. To demonstrate the possible advantages of the study of the inner logic of humoral medicine, ten medicinal plants are chosen and discussed.     

Molecular control of memory in nematode Caenorhabditis elegans

Model invertebrate organism Caenorhabditis elegans has become an ideal model to unravel the complex processes of memory. C. elegans has three simple forms of memory： memory for thermosensation, memory for chemosensation, and memory for mechanosensation. In the form of memory for mechanosensation, short-term memory, intermediate-term memory, and long-term memory have been extensively studied. The short-term memory and intermediate-term memory may occur in the presynaptic sensory neurons, whereas the long-term memory may occur in the postsynaptic interneurons. This review will discuss the recent progress on genetic and molecular regulation of memory in C. elegans.     

The role of memory in awareness of memory deficits in Alzheimer’s disease,schizophrenia, and brain injury

Patients with neuropsychiatric disorders such as Alzheimer’s disease (AD), schizophrenia (Sz), and brain injury (BI) often show memory deficits and lack of awareness of those deficits. This study aimed to investigate the role of memory in awareness of memory deficits and illness in multiple patient groups. Comparison of awareness profiles between groups can reveal common or distinct patterns of awareness and predictors, which may inform theories about the structure of awareness. Using the same standardized measures, AD (N = 27) Sz (N = 31), and BI (N = 26) patients were compared on memory functioning, awareness of illness, and awareness of memory deficits—measured by discrepancy of pretest estimate and actual test scores. All groups were poor at pretest estimation of memory functioning, particularly the AD and BI groups. In AD, patients with the lowest memory functioning rated their performance highest. The BI group and to a lesser extent the AD group showed improved estimations of performance following the memory test. Those with the poorest memory showed the greatest improvement in ratings accuracy post test. The relationship between memory and awareness of memory was stronger than the association between memory and awareness of illness. There was a double dissociation between awareness of memory and awareness of illness across patient groups. The study shows that awareness of memory is linked to memory functioning, while memory is only modestly related to awareness of illness. Dissociations in the role of memory in different domains of awareness and “online” awareness of performance provide information to refine cognitive models of awareness. However, the results should be interpreted with caution given the heterogeneous nature of the sample.     

Visual memory testing in older adults with age-related visual decline: a measure of memory performance or visual functioning?

Although we know that vision is correlated with memory performance in older adults, the implications for this in terms of neuropsychological assessment have not been investigated. Relationships among age, visual acuity, and visual and verbal memory in 89 community dwelling volunteers aged 60 to 87 years were examined. Vision was tested using the Landolt C and visual and verbal memory were assessed via the Visual Reproduction (VR) and Word List (WL) subtests from the Wechsler Memory Scale, Third Edition (WMS-III; Wechsler, 1997), respectively. Significant correlations were observed between vision and the VR and WL tasks. Hierarchical multiple regression analyses revealed that vision significantly increased the R2 for VR and WL after controlling for age and education. The effect of vision was not specific to visual memory. We conclude that vision is correlated with general memory function in older adults, and is not modality specific.     

Does abnormal non-rapid eye movement sleep impair declarative memory consolidation?: Disturbed thalamic functions in sleep and memory processing

Non-rapid eye movement (NREM) sleep has recently garnered support for its role in consolidating hippocampus-based declarative memories in humans. We provide a brief review of the latest research on NREM sleep activity and its association with declarative memory consolidation. Utilizing empirical findings from sleep studies on schizophrenia, Alzheimer's disease, and fibromyalgia, we argue that a significant reduction of slow-wave sleep and sleep spindle activity contribute to the development of deficits in declarative memory consolidation along with concomitant sleep disturbances commonly experienced in the aforementioned disorders. A tentative model is introduced to describe the mediating role of the thalamocortical network in disruptions of both declarative memory consolidation and NREM sleep. The hope is to stimulate new research in further investigating the intimate link between these two very important functions.     

Is selective mutism associated with deficits in memory span and visual memory?: an exploratory case–control study

Our main aim in this study was to explore the association between selective mutism (SM) and aspects of nonverbal cognition such as visual memory span and visual memory. Auditory-verbal memory span was also examined. The etiology of SM is unclear, and it probably represents a heterogeneous condition. SM is associated with language impairment, but nonspecific neurodevelopmental factors, including motor problems, are also reported in SM without language impairment. Furthermore, SM is described in Asperger's syndrome. Studies on nonverbal cognition in SM thus merit further investigation. Neuropsychological tests were administered to a clinical sample of 32 children and adolescents with SM (ages 6-17 years, 14 boys and 18 girls) and 62 nonreferred controls matched for age, gender, and socioeconomic status. We used independent t-tests to compare groups with regard to auditory-verbal memory span, visual memory span, and visual memory (Benton Visual Retention Test), and employed linear regression analysis to study the impact of SM on visual memory, controlling for IQ and measures of language and motor function. The SM group differed from controls on auditory-verbal memory span but not on visual memory span. Controlled for IQ, language, and motor function, the SM group did not differ from controls on visual memory. Motor function was the strongest predictor of visual memory performance. SM does not appear to be associated with deficits in visual memory span or visual memory. The reduced auditory-verbal memory span supports the association between SM and language impairment. More comprehensive neuropsychological studies are needed.