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PubMed2006

Immune memory, immune oblivion: a lesson from Funes the memorious.

We commonly think of the immune system as having a memory. However, memory is always accompanied by a complementary process of oblivion. Is there immune oblivion? In this theoretical paper, I address this question and suggest that oblivion is an integral aspect of memorization. In this context, I suggest that immune memory is an orchestration of reversible and irreversible processes of biological computation through feedback loops. Drawing on the linguistic metaphor, I inquire into the implications of this idea for a better understanding of immune memory and immune deficiency among the elderly.

Aging↗

PubMed2004

Verbal memory processes in schizophrenia patients and biological relatives of schizophrenia patients: intact implicit memory, impaired explicit recollection.

Verbal memory deficits are arguably the most common cognitive abnormalities in biological relatives of schizophrenia patients. Because verbal memory is a complex cognitive function, it is necessary to differentiate its intact and compromised aspects in order to reveal aberrant neural systems that reflect genetic risk in relatives of schizophrenia patients. Using an experimental verbal memory task, we examined encoding, free-recall, repetition priming, and recognition of verbal material in 22 schizophrenia patients, 22 first-degree biological relatives of schizophrenia patients, and 23 nonpsychiatric control participants. Schizophrenia patients exhibited intact repetition priming, but worse size judgment task performance (encoding), recall, and recognition than the control participants. Biological relatives of schizophrenia patients exhibited intact size judgment task performance, repetition priming, and recognition, but a free-recall deficit. Although size judgment task performance at encoding was associated with recall of verbal material in schizophrenia and control groups, in the relative group encoding performance was associated with the degree of repetition priming. Findings are consistent with impaired explicit recollection of verbal material, but intact implicit verbal memory in schizophrenia patients and biological relatives of schizophrenia patients.

Brief Psychiatric Rating Scale↗

PubMed1999

Errors made by animals in memory paradigms are not always due to failure of memory.

It is commonly assumed that errors in animal memory paradigms such as delayed matching to sample, radial mazes, and food-cache recovery are due to failures in memory for information necessary to perform the task successfully. A body of research, reviewed here, suggests that this is not always the case: animals sometimes make errors despite apparently being able to remember the appropriate information. In this paper a case study of this phenomenon is described, along with a demonstration of a simple procedural modification that successfully reduced these non-memory errors, thereby producing a better measure of memory.

Animals↗

PubMedDate not supplied

Aging and everyday memory: the beneficial effect of memory training.

The authors investigated elderly people's ability to benefit from specific memory training. Empirical evidence of cognitive aging shows a deterioration in working memory ability but also suggests that elderly people maintain the ability to acquire new information and strategies. The aim of the present study was to investigate the effects of two different mnemonic strategies (Loci mnemonic vs. Strategic training) in young and older adults and to evaluate the ability of the older groups to improve performance. Participants received extensive practice in the use of a specific strategy. Three groups of participants (20 adult, 20 younger elderly, and 20 older elderly) were tested in the laboratory, as well as in ecological conditions using a battery of cognitive tests. Questionnaires were also administrated to explore cognitive, metacognitive and emotive motivational aspects of working memory performance. The results show the efficacy of both trainings in improving performances in different tasks, particularly the ecological. The elderly benefit from strategies as much as younger people; nevertheless, the memory performances of the latter are higher. Differences between the two trainings are found only in the task evaluating ability to re-use learnt strategies in other unfamiliar situations. Improvement in performance was more pronounced for the strategic training.

Adult↗

PubMed2002

Post-trial administration of vasopressin in humans does not enhance memory formation (vasopressin and memory consolidation).

Many animal studies show an enhancing effect of vasopressin (VP) on memory, but not all human studies could confirm this finding. This study examined the influence of post-learning administration of VP (40 IU, intranasally) on the consolidation of declarative memories in healthy humans during different intervals of sleep and waking. We could not find any effect of VP on memory consolidation, but EEG activity indicated a significant arousing influence of VP. Results suggest that if VP affects memory function it might do so primarily at the stage of encoding of the materials to be learned but it leaves unaffected processes of consolidation.

Administration, Intranasal↗

PubMed2003

Cytokine-driven proliferation and differentiation of human naïve, central memory and effector memory CD4+ T cells.

Memory T lymphocytes divide in vivo in the absence of antigen maintaining a pool of central memory (T(CM)) and effector memory cells (T(EM)) with distinct effector function and homing capacity. We compared human CD4+ naïve T, T(CM) and T(EM) cells for their capacity to proliferate in response to cytokines, which have been implicated in T cell homeostasis. Interleukin (IL)-7 and IL-15 expanded with very high efficiency T(EM), while T(CM) were less responsive and naïve T cells did not respond at all. Dendritic cell (DC)-derived cytokines allowed naïve T cells to respond selectively to IL-4 and potently boosted the response of T(CM) to IL-7 and IL-15 by increasing the expression of the IL-2/IL-15Rss and the common gamma chain (gamma(c)). The ERK and the p38 MAP kinases were selectively required for TCR and cytokine-driven proliferation, respectively. Importantly, in cytokine-driven cultures T(CM) proliferated and some of the proliferating cells acquired effector function and non-lymphoid tissue homing capacity. Ex vivo BrdU incorporation experiments showed that both T(CM) and T(EM) proliferated under steady state conditions in vivo. Altogether these results provide a plausible mechanism for the maintenance of a polyclonal and functionally diverse repertoire of human CD4+ memory T cells and for a sustained antigen-independent generation of T(EM) from a pool of T(CM) cells.

Animals↗

PubMed2000

A cascade associative memory model with a hierarchical memory structure.

The introduction of a hierarchical memory structure into a cascade associative memory model for storing hierarchically correlated patterns improves the storage capacity and the size of the basins of attraction remarkably. A learning algorithm groups descendants (second-level patterns) according to their ancestors (first-level ones), and organizes the memory structure in a weight matrix where the groups are memorized separately. The weight matrix is, thus, in the form of a pile of covariance matrices, each of which is responsible for recalling only the descendants of each ancestor. Putting it simply, the model is multiplex associative memory. The recalling process proceeds as follows: the model first recalls the ancestor of a target descendant. Then, the dynamics with dynamic threshold combines the ancestor and the weight matrix to activate the covariance matrix for recalling only the descendants of the ancestor. This mechanism suppresses the cross-talk noise generated by the descendants of the other ancestors, and the recalling ability is enhanced.

Algorithms↗

PubMed2003

Language comprehension and working memory language comprehension and working memory deficits in patients with schizophrenia.

The present study examined the hypothesis that patients with schizophrenia have deficits in language comprehension compared to normal controls, and that these deficits are associated with disturbances in working memory (WM). In addition, we hypothesized that language comprehension deficits would be associated with the severity of specific symptoms in the patients (formal thought disorder and hallucinations). Participants were 27 stable outpatients with schizophrenia and 28 demographically similar controls. Language comprehension was measured by presenting sentences auditorily that varied in length and syntactic complexity, followed by two or three comprehension questions. We measured working memory by administering a reading span task. Results indicated that, as predicted, language comprehension deficits were significantly greater in patients with schizophrenia than controls. Also as predicted, working memory was strongly correlated with language comprehension performance in both patients with schizophrenia and controls. Contrary to our predictions, language comprehension and working memory deficits were not associated with either formal thought disorder or hallucinations.

Adult↗

PubMed2003

Pre-frontal executive committee for perception, working memory, attention, long-term memory, motor control, and thinking: a tutorial review.

As an explicit organizing metaphor, memory aid, and conceptual framework, the prefrontal cortex may be viewed as a five-member 'Executive Committee,' as the prefrontal-control extensions of five sub-and-posterior-cortical systems: (1) the 'Perceiver' (dominant-right-hemisphere ventral-lateral prefrontal cortex--VL/PERC-PFC) is the frontal extension of the ventral perceptual stream (the VL/PERC system) which represents the world and self in object coordinates; (2) the 'Verbalizer' (dominant-left-hemisphere ventral-lateral prefrontal cortex system--VL/VERB-PFC) is the frontal extension of the language stream (the VL/VERB system) which represents the world and self in language coordinates; (3) the 'Motivator' (ventral/medial-orbital pre-frontal cortex--VMO-PFC) is the frontal cortical extension of a subcortical extended-amygdala stream (the VMO system) which represents the world and self in motivational/emotional coordinates; (4) the 'Attender' (dorsal-medial/anterior cingulate--DM/AC-PFC) is the frontal cortical extension of a subcortical extended-hippocampal stream (the DM/AC system) which represents the world and self in spatiotemporal coordinates and directs attention to internal and external events; and (5) the 'Coordinator' (the dorsolateral prefrontal cortex--DL-PFC) is the frontal extension of the dorsal perceptual stream (the DL system) which represents the world and self in body- and eye-coordinates and controls willed action and working memory. This tutorial review examines the interacting roles of these five systems in perception, working memory, attention, long-term memory, motor control, and thinking.

Attention↗

PubMed2001

The mode of short-term memory encoding as indicated by event-related potentials in a memory scanning task with distractions.

OBJECTIVE: Auditory event-related potentials (ERPs) were recorded during the performance of a memory scanning task, with and without distracters between the memorized items and the probe. The effect of distracters with different phonological/semantic characteristics was tested, to indicate the encoding mode in short-term memory. METHODS: Three types of sets ('memorized sets') were presented to the subject before the probe: 4 memorized digits, two memorized digits with two distracter digits and two memorized digits with two noise distracters. Potentials in response to the set items were averaged separately according to stimulus type and position in the set. Potentials in response to the probe were averaged according to the preceding stimulus sequence: 4 memorized digits, two distracter digits or two noise distracters. RESULTS: The early components (N1, P2) differed between distracter items and memorized items, indicating lower attention allocation to distracter items. In contrast, the late components (N2, P3) indicated similar processing of distracters and memorized items. Behavioral measures indicated shorter scanning times of sets with distracters. The early ERP components in response to the probe (P2, N2) indicated differences among probes according to the preceding combinations of memorized items and distracters. The late component (P3) indicated different speeds (latencies) of scanning and comparison for series with compared to without distracters, but similar processing resource allocation (amplitudes). Processing was prolonged when the distracter items were phonological. CONCLUSIONS: This study shows that distracters affect both the memorization process and the scanning and comparison in short-term memory. The stronger distraction by stimuli that are phonologically similar to the memorized items supports phonological processing in short-term memory.

Adolescent↗

PubMed2006

Memories of the terrorist attacks of September 11, 2001: a study of the consistency and phenomenal characteristics of flashbulb memories.

In this study, I investigated students' memories of the terrorist attacks of September 11, 2001, carried out by Al Qaeda terrorists against the World Trade Center in New York and the Pentagon in Washington. Participants completed on two occasions (2 weeks and 8 months after the events took place) a memory questionnaire that included an assessment of the phenomenal richness of their memories. The results showed that the participants remembered very well the circumstances in which they first heard about the terrorist attacks, that they were very confident about this information, and that these memories were characterized by a high phenomenal richness. Over time, there was a decrease in all of these variables, but people's ratings of phenomenology and confidence were still very high.

Adolescent↗

PubMed2000

Retrieving positive memories to regulate negative mood: consequences for mood-congruent memory.

Several researchers have suggested that mood-incongruency effects are due to a mood-regulatory process in which people retrieve positive memories to repair negative moods. The present studies tested this idea by manipulating mood-repair strategies and examining their impact on positive and negative memory retrieval. Mood-congruent retrieval occurred when participants stayed focused on events associated with their negative mood; mood-incongruent retrieval occurred when participants engaged in positive reappraisal (when they reinterpreted events as having positive outcomes). The effects of these strategies on memory retrieval also interacted with personality traits related to negative mood regulation. Individuals high in such traits showed stronger mood-incongruent memory than did individuals low in negative mood-regulation traits. Discussion focuses on integrating mood-regulatory variables and personality variables into existing mood-congruency theories (e.g., associative network models).

Adult↗

PubMed2002

Outstanding memories: the positive and negative effects of nudes on memory.

A picture of a nude isolated in a series of pictures of clothed models was quite memorable, but when compared with a clothed picture, the nude impaired memory for background picture derails as well as pictures immediately following the nude (anterograde amnesia). Recall of details given picture-gist recall, as well as recognition of person details, were equivalent in the clothed and nude conditions. A clothed picture isolated in a series of nudes did not hurt memory for background information, nor did it produce anterograde amnesia. Apparently, distinctiveness supports good memory for the gist of the nude or clothed pictures. However, distinctiveness is not responsible for the anterograde amnesia and poor memory for background details found with nudes.

Affect↗

PubMed1986

Memory complaint and memory performance in the depressed elderly.

Depressed and nondepressed elderly subjects recruited in the context of a large epidemiological study of health were compared on measures of self-reported memory disturbance and an objective index of memory performance (free recall). Three groups were studied including (a) subjects meeting Research Diagnostic Criteria (RDC) for major depression, (b) subjects with high levels of self-reported depressive symptoms who did not meet RDC for major depression, and (c) subjects with low levels of self-reported depressive symptoms. Subjects with high depression symptom levels reported significantly higher levels of memory complaint than did subjects with low symptom levels. However, there were no differences in self-reported memory disturbance as a function of depression diagnosis. Further, there were no significant differences between groups on the free-recall measure, either as a function of symptom level or diagnosis. It is argued that symptom severity rather than diagnosis of depression is important in determining impairment in depressed elderly people.

Aged↗

PubMed1992

Adult age differences in short-term memory and subsequent long-term memory for actions.

Short-term memory for actions was investigated for young adult and elderly adult subjects with the Brown-Peterson procedure at retention intervals of 0 and 15 s. The short-term memory trials were followed by the long-term recall of the prior to-be-remembered actions. The 15-s retention interval was filled either with no activity or with 1 of 3 different interfering activities. Verbal interference had little effect on short-term memory at either age level. Actions performed in the interval either by the subjects or by the experimenter produced significantly lower recall scores at each age level, with the decrement being more pronounced for the elderly than for the young subjects. The long-term memory results indicated that successful short-term recall enhanced later long-term recall, regardless of age level.

Adult↗

PubMed1994

Memory knowledge and memory monitoring in adulthood.

Age differences in 2 specific processing dimensions of metamemory, namely memory knowledge and memory monitoring, were examined. Young and old Ss recalled lists of words paired with letter, rhyme, and meaning cues over 2 trials. On both trials, Ss made predictions of recall likelihood on presentation of each word-cue pair. No age differences in initial predictions (i.e., prior memory knowledge) were apparent, whereas age-based performance differences were observed. On Trial 2, both young and old Ss significantly revised their predictions; however, old adults monitored only global discrepancies between previous expectation and performance. Young adults raised and lowered expectations across cue types in accordance with their previous performance. Age differences in processing speed accounted for some but not all of the memory-monitoring differences.

Adolescent↗

PubMed2004

College students' memory for vocabulary in their majors: evidence for a nonlinear relation between knowledge and memory.

The effect of domain knowledge on students' memory for vocabulary terms was investigated. Participants were 142 college students (94 education majors and 48 business majors). The measure of domain knowledge was the number of courses completed in the major. Students recalled three different lists (control, education, and business) of 20 words. Knowledge effects were estimated controlling for academic aptitude, academic achievement, and general memory ability. Domain-specific knowledge consistently predicted recall, above and beyond the effect of these control variables. Moreover, nonlinear models better represented the relation between knowledge and memory, with very similar functions predicting recall in both knowledge domains. Specifically, early in the majors more classes corresponded with increased memory performance, but a plateau period, when more classes did not result in higher recall, was evident for both majors. Longitudinal research is needed to explore at what point in learning novices' performance begins to resemble experts' performance.

Adolescent↗

PubMed2005

The selective 5-HT6 receptor antagonist Ro4368554 restores memory performance in cholinergic and serotonergic models of memory deficiency in the rat.

Antagonists at serotonin type 6 (5-HT(6)) receptors show activity in models of learning and memory. Although the underlying mechanism(s) are not well understood, these effects may involve an increase in acetylcholine (ACh) levels. The present study sought to characterize the cognitive-enhancing effects of the 5-HT(6) antagonist Ro4368554 (3-benzenesulfonyl-7-(4-methyl-piperazin-1-yl)1H-indole) in a rat object recognition task employing a cholinergic (scopolamine pretreatment) and a serotonergic- (tryptophan (TRP) depletion) deficient model, and compared its pattern of action with that of the acetylcholinesterase inhibitor metrifonate. Initial testing in a time-dependent forgetting task employing a 24-h delay between training and testing showed that metrifonate improved object recognition (at 10 and 30 mg/kg, p.o.), whereas Ro4368554 was inactive. Both, Ro4368554 (3 and 10 mg/kg, intraperitoneally (i.p.)) and metrifonate (10 mg/kg, p.o., respectively) reversed memory deficits induced by scopolamine and TRP depletion (10 mg/kg, i.p., and 3 mg/kg, p.o., respectively). In conclusion, although Ro4368554 did not improve a time-related retention deficit, it reversed a cholinergic and a serotonergic memory deficit, suggesting that both mechanisms may be involved in the facilitation of object memory by Ro4368554 and, possibly, other 5-HT(6) receptor antagonists.

Animals↗