Getting better without memory

Does the tendency to adjust appraisals of ourselves in the past and future in order to maintain a favourable view of ourselves in the present require episodic memory? A developmental amnesic person with impaired episodic memory (HC) was compared with two groups of age-matched controls on tasks assessing the Big Five personality traits and social competence in relation to the past, present and future. Consistent with previous research, controls believed that their personality had changed more in the past 5 years than it will change in the next 5 years (i.e. the end-of-history illusion), and rated their present and future selves as more socially competent than their past selves (i.e. social improvement illusion), although this was moderated by self-esteem. Despite her lifelong episodic memory impairment, HC also showed these biases of temporal self-appraisal. Together, these findings do not support the theory that the temporal extension of the self-concept requires the ability to recollect richly detailed memories of the self in the past and future.     

An Allais paradox without mental time travel

The capacity to anticipate future experiences of regret has been hypothesized to explain otherwise irrational aspects of human decision‐making, including the certainty effect (Kahneman and Tversky (1979) Econometrica 47:263–291) and the common ratio effect (Allais (1953) Econometrica 21:503–546). The anticipated regret hypothesis predicts that individuals incapable of episodically imagining their personal futures, as has been reported for people with extensive damage to medial temporal lobe structures and resulting deficits in episodic thought, should be immune to these effects. We report that K.C., who has extensive bilateral damage to his hippocampus and adjacent medial temporal lobe structures and nearly complete deficits in his ability to episodically imagine his personal future, nonetheless displays both the certainty and the common ratio effects. These results suggest that the episodic anticipation of future regret does not explain the general human tendency to display the certainty and common ratio effects. © 2014 Wiley Periodicals, Inc.     

Hippocampal Insulin Resistance Impairs Spatial Learning and Synaptic Plasticity

Insulin receptors (IRs) are expressed in discrete neuronal populations in the central nervous system, including the hippocampus. To elucidate the functional role of hippocampal IRs independent of metabolic function, we generated a model of hippocampal-specific insulin resistance using a lentiviral vector expressing an IR antisense sequence (LV-IRAS). LV-IRAS effectively downregulates IR expression in the rat hippocampus without affecting body weight, adiposity, or peripheral glucose homeostasis. Nevertheless, hippocampal neuroplasticity was impaired in LV-IRAS–treated rats. High-frequency stimulation, which evoked robust long-term potentiation (LTP) in brain slices from LV control rats, failed to evoke LTP in LV-IRAS–treated rats. GluN2B subunit levels, as well as the basal level of phosphorylation of GluA1, were reduced in the hippocampus of LV-IRAS rats. Moreover, these deficits in synaptic transmission were associated with impairments in spatial learning. We suggest that alterations in the expression and phosphorylation of glutamate receptor subunits underlie the alterations in LTP and that these changes are responsible for the impairment in hippocampal-dependent learning. Importantly, these learning deficits are strikingly similar to the impairments in complex task performance observed in patients with diabetes, which strengthens the hypothesis that hippocampal insulin resistance is a key mediator of cognitive deficits independent of glycemic control.     

Cueing the personal future to reduce discounting in intertemporal choice: Is episodic prospection necessary?

How does the ability to imagine detailed future experiences (i.e., episodic prospection) contribute to choices between immediate and delayed rewards? Individuals with amnesia do not show abnormally steep discounting in intertemporal choice, suggesting that neither medial temporal lobe (MTL) integrity nor episodic prospection is required for the valuation of future rewards (Kwan et al. ( ), Hippocampus, 22:1215‐1219; Kwan et al. (2013), J Exp Psychol, 142:1355‐1369 2013). However, hippocampally mediated episodic prospection in healthy adults reduces the discounting of future rewards (Peters and Büchel (2010), Neuron, 66:138‐148; Benoit et al. (2011), J Neurosci, 31:6771‐6779), raising the possibility that MTL damage causes more subtle impairments to this form of decision‐making than noted in previous patient studies. Intertemporal choice appears normal in amnesic populations, yet they may be unable to use episodic prospection to adaptively modulate the value assigned to future rewards. To investigate how the extended hippocampal system, including the hippocampus and related MTL structures, contributes to the valuation of future rewards, we compared the performance of six amnesic cases with impaired episodic prospection to that of 20 control participants on two versions of an intertemporal choice task: a standard discounting task, and a cued version in which cues prompted them to imagine specific personal future events temporally contiguous with the receipt of delayed rewards. Amnesic individuals' intertemporal choices in the standard condition were indistinguishable from those of controls, replicating previous findings. Surprisingly, performance of the amnesic cases in the cued condition indicates that amnesia does not preclude flexible modulation of choices in response to future event cues, even in the absence of episodic prospection. Cueing the personal future to modulate decisions appears to constitute a less demanding or a qualitatively different (e.g., personal semantic) form of prospection that is not as sensitive to MTL damage as prospective narrative generation. © 2015 Wiley Periodicals, Inc.     

Neural activity patterns evoked by a spouse's incongruent emotional reactions when recalling marriage‐relevant experiences

Resonance with the inner states of another social actor is regarded as a hallmark of emotional closeness. Nevertheless, sensitivity to potential incongruities between one's own and an intimate partner's subjective experience is reportedly also important for close relationship quality. Here, we tested whether perceivers show greater neurobehavioral responsiveness to a spouse's positive (rather than negative) context‐incongruent emotions, and whether this effect is influenced by the perceiver's satisfaction with the relationship. Thus, we used fMRI to scan older long‐term married female perceivers while they judged either their spouse's or a stranger's affect, based on incongruent nonverbal and verbal cues. The verbal cues were selected to evoke strongly polarized affective responses. Higher perceiver marital satisfaction predicted greater neural processing of the spouse's (rather than the strangers) nonverbal cues. Nevertheless, across all perceivers, greater neural processing of a spouse's (rather than a stranger's) nonverbal behavior was reliably observed only when the behavior was positive and the context was negative. The spouse's positive (rather than negative) nonverbal behavior evoked greater activity in putative mirror neuron areas, such as the bilateral inferior parietal lobule (IPL). This effect was related to a stronger inhibitory influence of cognitive control areas on mirror system activity in response to a spouse's negative nonverbal cues, an effect that strengthened with increasing perceiver marital satisfaction. Our valence‐asymmetric findings imply that neurobehavioral responsiveness to a close other's emotions may depend, at least partly, on cognitive control resources, which are used to support the perceiver's interpersonal goals (here, goals that are relevant to relationship stability). Hum Brain Mapp 36:4164–4183, 2015. © 2015 Wiley Periodicals, Inc.     

Lifestyle Risk Factors Associated with Arm Swelling Among Women with Breast Cancer

Background

Breast cancer-related lymphedema (BCRL) is a feared complication for breast cancer patients who have undergone axillary surgery. Although clinical risk factors for BCRL are defined, data are sparse regarding common exposures that might induce incident arm swelling. The goal of this study was to quantify the association between common exposures thought to be potential risk factors and the occurrence of incident arm swelling among breast cancer survivors with or at risk for BCRL.

Methods

This is a prospective subanalysis of the Physical Activity and Lymphedema (PAL) trial, a randomized controlled trial of 295 breast cancer survivors. Participants reported their exposure to 30 different potential risk factors at 3 month intervals for 1 year. Incident arm swelling was defined as a ≥5 % increase in interlimb water volume difference between two consecutive time points.

Results

Twenty-seven participants (9 %) experienced incident arm swelling and 268 patients (91 %) did not. Sauna use was the only exposure that was significantly predictive of incident arm swelling (p = 0.05). Nonwhite and nonblack participants had a significantly increased risk for experiencing incident arm swelling (p = 0.005 for both comparisons).

Conclusions

In our patient cohort, many common exposures that have been reported to be risk factors did not prove to have a significant predictive relationship for incident arm swelling. This study supports the recommendation that breast cancer patients who have had axillary surgery should avoid sauna use. The results do not confirm the need for other restrictions that may interfere with the quality of life in women with breast cancer.