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.     

Applying evidence to support ethical decisions: Is the placebo really powerless?

Using placebos in day-to-day practice is an ethical problem. This paper summarises the available epidemiological evidence to support this difficult decision. Based on these data we propose to differentiate between placebo and “knowledge framing”. While the use of placebo should be confined to experimental settings in clinical trials, knowledge framing — which is only conceptually different from placebo — is a desired, expected and necessary component of any doctor-patient encounter. Examples from daily practice demonstrate both, the need to investigate the effects of knowledge framing and its impact on ethical, medical, economical and legal decisions. An earlier version of this paper was presented at an international conference, “Placebo: Its Action and Place in Health Research Today,” held in Warsaw, Poland on 12–13 April, 2003.     

Fear-relevant selective associations and social anxiety: absence of a positive bias

An illusory correlation paradigm was used to compare high and low socially anxious individuals' initial, on-line and a posteriori covariation estimates between emotional faces and aversive, pleasant and neutral outcomes. Overall, participants demonstrated an initial expectancy bias for aversive outcomes following angry faces, and pleasant outcomes following happy faces. On-line expectancy biases indicated that initial biases were extinguished during the task, with the exception of low socially anxious individuals who continued to over-associate positive social cues with pleasant outcomes. In addition to lacking this protective positive on-line bias, the high social anxiety group reported retrospectively more negative social cues than the low socially anxious group. Findings are discussed in relation to similar evidence from recent interpretive and memory paradigms.     

Interpretation of ambiguous information in clinical depression

The present study used two cognitive tasks--a text comprehension task and a homophone task--to investigate whether clinically depressed individuals have a negative bias when interpreting ambiguous information. Previous research indicates that both tasks are sensitive to anxiety-related interpretive biases, and that the former is less prone to response bias effects. Negative memory biases were also assessed. Results showed that, compared with normal controls, depressed individuals made more negative interpretations on the homophone task, and they also showed an enhanced negative recall bias. However, the groups did not differ in interpretative bias on the text comprehension task. Possible explanations of the results are discussed, including the potential influences of self-referent processing and response bias.     

Time course of attentional bias for fear-relevant pictures in spider-fearful individuals

The time course of attentional biases for spider stimuli was assessed in two groups of individuals with high or low levels of spider fear. Pairs of photographs of spiders and cats were presented in a visual probe task with three exposure durations: 200, 500 and 2000 ms. Results indicated greater attentional bias for spider stimuli in high fear, than in low fear, individuals in the 200 ms condition. The attentional bias in the high fear group significantly reduced as stimulus exposure duration increased, with no significant biases found in the longer exposure conditions. Results support the view that high fear is associated with an enhanced initial attentional bias for fear-relevant stimuli, but that this attentional bias is not maintained over time.     

Why aren't identical twins linguistically identical? Genetic, prenatal and postnatal factors

Results of twin studies clearly demonstrate that genetic factors play an important role in the rate of language acquisition and linguistic proficiency attained by normal and impaired children and adults [see Stromswold, K. (2001). The heritability of language: A review and meta-analysis of twin, adoption and linkage studies. Language, 77, 647-723.]. That said, twin-based heritability estimates for language rarely exceed .6 and monozygotic (MZ) twins (who are usually assumed to have identical genetic and environmental endowments) sometimes have very different linguistic profiles. In addition, twins are more likely to suffer linguistic delays and impairments than singletons. Postnatal factors, such as differences in linguistic input twins receive, are usually assumed to be the major reason for these findings. This paper discusses how genetic, epigenetic, and perinatal environmental factors can lower heritability estimates for language, cause MZ twins to be linguistically discordant, and increase the risk of language impairments in twins. We present results from our ongoing Perinatal Environment and Genetic Interaction (PEGI) study that suggest that perinatal environmental factors affect linguistic development more than postnatal factors, and that postnatal factors affect cognitive development more than perinatal factors. Because perinatal factors are overwhelming biological, whereas postnatal factors tend to be psychosocial (e.g., how and how much parents speak to their children), these results support nativist/biological theories of language and language development and call into question empiricist/emergentist theories. These results are also consistent with modularist theories of language. We end by suggesting new methods that can be used to tease apart the effects of prenatal and postnatal environment and to investigate how these factors interact with genetic factors.     

Ethical Issues in Cancer Genetics: 1) Whose Information Is It?

This article presents and discusses four clinical cases that exemplify the complexity of ethical dilemmas concerning the provider's obligation to disclose or withhold genetic information from patients. Case 1: What is the responsibility of the cancer genetics provider to ensure that a positive test results is shared with distant relatives? Case 2: To ensure that results go to at-risk relatives, do we have the right to ignore the wishes of the designated next-of-kin? Case 3: Do we have the right to reveal a familial BRCA1 mutation to a patient's relative, who is at 50% risk? Case 4: Do we have an obligation to reveal that a patient is not a blood relative and therefore, not at risk to have inherited a familial mutation? These cases form the basis for discussing the provider's dual obligations to keeping patient confidentiality and informing patients and families about risk (i.e. duty to warn). We also provide a summary of consensus points and additional discussion questions for each case.     

Motor initiation and execution in patients with conversion paralysis

Motor initiation and motor execution in four patients with conversion paralysis were investigated in a non-affected motor modality (speech). In line with the hypothesis of dissociated control in conversion disorder [Cognit. Neuropsychiatry 8 (1) (2001) 21] motor initiation, but not response duration, was expected to be impaired. The motor initiation times (reaction time: RT) and motor execution times (response duration: RD) were compared on four RT-tasks that required the production of a verbal response: a simple choice RT-task, a mental letter rotation task, and an implicit and an explicit mental hand rotation task. Because conversion disorder is expected to primarily involve an impairment in the initiation of movement, we expected the following task characteristics to uniquely affect RT and not RD: type of instruction (implicit versus explicit instructed imagery), angle of rotation, and target arm (affected versus non-affected arm). The results indeed showed the task characteristics to significantly affect the participants' RT and not their RD. It was concluded that conversion paralysis is associated with a specific impairment in the explicit initiation of processes with a spatial and motor component.     

Social recognition memory requires two stages of protein synthesis in mice

Olfactory recognition memory was tested in adult male mice using a social discrimination task. The testing was conducted to begin to characterize the role of protein synthesis and the specific brain regions associated with activity in this task. Long-term olfactory recognition memory was blocked when the protein synthesis inhibitor anisomycin was injected 20 min before, immediately after, or 6 h after sampling. No effect was observed when anisomycin was administered 3 h or 18 h after sampling. Immunohistochemical analysis of Fos expression revealed that sampling-like exposure to a juvenile increased the activity of a subset of cells in the accessory olfactory bulb and the brain areas that are associated with it. Additionally, increased Fos expression was measured in the main olfactory bulb and the piriform cortex, whereas no signs of activation were seen in the cortical nucleus of the amygdala, all components of the main olfactory system. No increases in Fos immunoreactivity were observed after 4 h. Our data suggest that long-lasting olfactory recognition memory requires two stages of protein synthesis. The first stage takes place within 1-2 h and the second stage between 6-7 h after sampling. The first but not the second stage is paralleled by an increase in the number of Fos-immunoreactive cells in brain areas associated with both the main and accessory olfactory systems. It therefore appears that the role of the second stage of protein synthesis in recognition memory depends on the integrity of the first stage of protein synthesis.