A behavioural and ERP investigation of the wearable camera photo review in autobiographical memory.

Wearable camera photo review has successfully been used to enhance memory, yet very little is known about the underlying mechanisms. Here, the sequential presentation of wearable camera photos - a key feature of wearable camera photo review - is examined using behavioural and EEG measures. Twelve female participants were taken on a walking tour, stopping at a series of predefined targets, while wearing a camera that captured photographs automatically. A sequence of four photos leading to these targets was selected (∼ 200 trials) and together with control photos, these were used in a recognition task one week later. Participants' recognition performance improved with the sequence of photos (measured in hit rates, correct rejections, & sensitivity), revealing for the first time, a positive effect of sequence of photos in wearable camera photo review. This has important implications for understanding the sequential and cumulative effects of cues on episodic remembering. An old-new ERP effect was also observed over visual regions for hits vs. correct rejections, highlighting the importance of visual processing not only for perception but also for the location of activated memory representations.

Positivity bias in past and future episodic thinking: Relationship with anxiety, depression, and retrieval-induced forgetting.

Positivity biases in autobiographical memory and episodic future thinking are considered important in mental wellbeing and are reduced in anxiety and depression. The inhibitory processes underlying retrieval-induced forgetting (RIF) have been proposed to contribute to these biases. This investigation found reduced positivity in past and future thinking to be associated with reduced memory specificity alongside greater levels of anxiety, depression, and rumination. Most notably, however, RIF was found to significantly predict memory valence. This indicates that RIF may be important in maintaining such biases, facilitating the forgetting of negative memories when a positive item is actively retrieved.

Haemodynamic determinants of elevated pulse wave velocity during acute isometric handgrip exercise.

BACKGROUND: Measurement of pulse wave velocity (PWV) provides a reliable index of vascular stiffness. Despite its widespread application, the physiological interrelationships between PWV, blood pressure (BP) and in particular, heart rate (HR), have yet to be fully elucidated. Furthermore, little is known about altered arterial compliance during acute exercise. AIM: To examine the effects of 3-min supine non-dominant isometric handgrip exercise (ISOMEX), performed at 30% of maximum voluntary contraction, on carotid-radial PWV, BP and HR in the dominant arm of 51 healthy subjects. RESULTS: During exercise, PWV correlated strongly with diastolic BP (r = 0.55, p < 0.01) and mean arterial pressure (r = 0.51, p < 0.01). PWV and HR failed to correlate at rest or during exercise. CONCLUSION: ISOMEX invoked an elevated PWV, which is predominantly related to BP or factors determining it, and not HR. The carotid-radial PWV stress test is a simple measurement that may have prognostic potential for use in large-scale population studies.

Nuclear magnetic resonance spectroscopic investigations of the human myocardium.

Magnetic resonance spectroscopy is a noninvasive technique for measuring the concentration of metabolites both in vivo and in solutions. The technique exploits the nuclear spin of certain isotopes, and measurements of signals from the nuclei of phosphorus atoms ((31)P) have provided much new information about high-energy phosphates and reaction fluxes in energy provision and utilization. The method has been systematically applied in the isolated heart preparation and the surgically exposed heart, and the effects of ischemia and other interventions have been documented. In humans, the ratio of phosphocreatine to adenosine triphosphate in the heart that has been determined both at rest and during exercise has been shown to be a sensitive index for impairment in cardiac metabolism in patients with myocardial hypertrophy due to aortic valve disease and during hand-grip exercise in patients with ischemia. It is now practical to use (31)P magnetic resonance spectroscopy to extend our understanding of myocardial metabolism in health and disease and to assess the response to therapy and the rejection of the transplanted heart.

The construction of autobiographical memories in the self-memory system.

The authors describe a model of autobiographical memory in which memories are transitory mental constructions within a self-memory system (SMS). The SMS contains an autobiographical knowledge base and current goals of the working self. Within the SMS, control processes modulate access to the knowledge base by successively shaping cues used to activate autobiographical memory knowledge structures and, in this way, form specific memories. The relation of the knowledge base to active goals is reciprocal, and the knowledge base "grounds" the goals of the working self. It is shown how this model can be used to draw together a wide range of diverse data from cognitive, social, developmental, personality, clinical, and neuropsychological autobiographical memory research.

Alterations of skeletal muscle metabolism in humans studied by phosphorus 31 magnetic resonance spectroscopy in congestive heart failure.

Muscle metabolism of the finger flexor muscle of the dominant arm was examined in patients with congestive heart failure and age-related controls. Phosphocreatine utilization and decrease in pH during exercise was significantly greater in patients than in controls. Recovery rates were slow in some of these patients. Measurements of forearm blood flow at rest or during exercise were not significantly reduced in patients compared with controls. The inorganic phosphate peak was split during exercise in some of the patients, suggesting the presence of more glycolytic fibers in their muscles. These observations suggest that metabolic abnormalities may be present in the skeletal muscles of patients with heart failure that are not due to reduced nutritive blood flow. This may, in part, explain the lack of correlation between measurements of cardiac function and exercise tolerance in these patients.

Changes in memory awareness during learning: the acquisition of knowledge by psychology undergraduates.

First-year psychology students took multiple-choice examinations following each of 4 lecture courses and 3 laboratory research methods courses. One lecture course was later retested. Students indicated state of memory awareness accompanying each answer: recollective experience (remember), "just know" (know), feeling of familiarity (familiarity), or guess. On the lecture courses, higher performing students differed from other students because they had more remember responses. On research methods, higher performing students differed because they knew more, and in the delayed retest, higher performing students differed because they now knew rather than remembered more. These findings demonstrate a shift from remembering to knowing, dependent upon level attained, type of course, and retention interval, and suggest an underlying shift in knowledge representation from episodic to semantic memory. The authors discuss theoretical and educational implications of the findings.

Neuropeptide Y and vasoactive intestinal polypeptide in cerebral arteries of the rat: relationships between innervation pattern and mechanical response.

Possible relationships between the density of peptide innervation and the contractile response of rat cerebral arteries to exogenously applied neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) were examined. The effects of NPY on membrane potential and reactivity of cerebral arteries to exogenous norepinephrine also were studied. In normally innervated arteries there was no apparent correlation between degree of innervation and response to NPY. Marked, prolonged tachyphylaxis to NPY and VIP was observed following brief exposure to these peptides. Surgical removal of the superior cervical ganglia or the sphenopalatine ganglia greatly reduced and, in some cases, eliminated NPY- or VIP-immunoreactive perivascular nerves from cerebral arteries. However, responses of denervated middle cerebral arteries to exogenous NPY or VIP were not different from responses of innervated arteries. Doses of NPY that induced maximal contraction caused no change in membrane potential of the middle cerebral artery. NPY also did not alter the response of cerebral arteries to exogenous norepinephrine. Finally, electrical stimulation of normal or denervated arteries caused only minor constrictor or dilator responses. These results do not support a substantial role for peptidergic perivascular nerves in regulation of pial arterial contractility in the rat.

Flashbulb memories in older adults.

In this study of age differences in flashbulb memory, groups of young and older adults gave detailed accounts of how they heard the news of the resignation of the British Prime Minister Margaret Thatcher. They were tested within 14 days after the event and again 11 months later. They also gave ratings for the encoding variables (surprise, emotion, importance, knowledge, and interest) and for frequency of rehearsal. Memories that met a strict criterion of consistency between the original and delayed responses were classified as flashbulb memories. Although 90% of young Ss had flashbulb memories, only 42% of the elderly met the criterion. The age groups also differed in the type of details remembered and in the relationship between the encoding and rehearsal variables and the occurrence of flashbulb memory. The age-related deficit in flashbulb memory is related to source amnesia and to a deficit in memory for context.

Recurrent Listeria monocytogenes meningitis in a heart transplant recipient.

A case of recurrent Listeria monocytogenes meningitis is reported, the two episodes arising 4 months and 8 months after the patient had received a heart transplant. Both episodes immediately followed increased doses of corticosteroids for allograft rejection. The source of infection was not identified. Previous reports and possible explanations of recurrent L. monocytogenes infection are reviewed.

Pictures, images, and recollective experience.

Five experiments investigated the influence of picture processing on recollective experience in recognition memory. Subjects studied items that differed in visual or imaginal detail, such as pictures versus words and high-imageability versus low-imageability words, and performed orienting tasks that directed processing either toward a stimulus as a word or toward a stimulus as a picture or image. Standard effects of imageability (e.g., the picture superiority effect and memory advantages following imagery) were obtained only in recognition judgments that featured recollective experience and were eliminated or reversed when recognition was not accompanied by recollective experience. It is proposed that conscious recollective experience in recognition memory is cued by attributes of retrieved memories such as sensory-perceptual attributes and records of cognitive operations performed at encoding.

Sensory-perceptual episodic memory and its context: autobiographical memory.

Episodic memory is reconceived as a memory system that retains highly detailed sensory perceptual knowledge of recent experience over retention intervals measured in minutes and hours. Episodic knowledge has yet to be integrated with the autobiographical memory knowledge base and so takes as its context or referent the immediate past of the experiencing self (or the 'I'). When recalled it can be accessed independently of content and is recollectively experienced. Autobiographical memory, in contrast, retains knowledge over retention intervals measured in weeks, months, years, decades and across the life span. Autobiographical knowledge represents the experienced self (or the 'me'), is always accessed by its content and, when accessed, does not necessarily give rise to recollective experience. Instead, recollective experience occurs when autobiographical knowledge retains access to associated episodic memories. In this reworking of the 'episodic memory' concept autobiographical memory provides the instantiating context for sensory-perceptual episodic memory.

Remembering, familiarity, and source monitoring.

Two experiments investigated recollective experience in a source monitoring task. Subjects saw an array of objects and performed, watched, or imagined actions involving pairs of objects. In a subsequent recognition test, subjects indicated whether their recognition judgements were made on the basis of conscious recollective experience ("remember" responses), or on some other basis such as familiarity ("know" responses). The proportions of correct "remember" responses for both objects and actions decreased from performed, through watched, to imagined actions, whereas the proportions of correct "know" responses were uninfluenced by the source of the memories. In addition, the relationship between recollective experience and accuracy of source judgement varied across sources. Source accuracy for performed actions was obtained only in "remember" responses, whereas source accuracy for performed actions was obtained only in "remember" responses, whereas source accuracy for imagined actions was obtained only in "know" responses. Source accuracy for watched actions was obtained in both "remember" and "know" responses. The findings suggest that the types of memory attributes available at retrieval determine the quality of subsequent memory experience, and it is proposed that memories with strongly self-referential attributes (arising from performed actions) powerfully cue recollective experience during retrieval.

Effects of beta-adrenergic blockade on the ventilatory responses to hypoxic and hyperoxic exercise in man.

1. The ventilatory responses to step changes from rest to 100 W cycling exercise were studied in five healthy human subjects. Exercise was performed in hypoxia (end-tidal O2 pressure, PET,O2, 50-55 mmHg), a condition characterized by a marked enhancement of arterial chemoreceptor activity, and in hyperoxia (PET,O2 greater than 250 mmHg), a condition in which arterial chemoreceptor activity is largely suppressed. The subjects were studied at each O2 level after placebo and after an oral dose of 120 mg propranolol. 2. The magnitude of phase 1, the immediate, rapid ventilatory response at the onset of work, was unaffected by hypoxia and at both oxygen levels it was also unaffected by propranolol. 3. Phase 2, analysed from 20 to 120 s after the onset of exercise, was significantly affected by both O2 level and beta-blockade. The kinetics of the ventilatory changes in this phase were well described in all four conditions by a simple exponential function. The overall mean time constants after placebo were shorter in hypoxia (31.0 s) than in hyperoxia (40.2 s), and at each O2 level longer after propranolol, in hypoxia 61.3 s and in hyperoxia 106.0 s. 4. Continuous analysis of gas sampled at the mouth with a mass spectrometer showed constancy of end-tidal PCO2 throughout the step change in hypoxia both with and without beta-blockade. In contrast, in both hyperoxic conditions PET,CO2 rose, mainly in phase 2, to a value 5-6 mmHg higher than the starting value. 5. The steady-state ventilation was higher in hypoxia than in hyperoxia, and end-tidal CO2 pressure, PET,CO2, correspondingly lower. Neither ventilation nor PCO2 were, however, affected by propranolol in either condition. 6. It is concluded that the arterial chemoreceptors are important for both the rate of adaptation of ventilation to a new rate of metabolism during a step change of work rate, and for the matching of ventilation to CO2 flow which normally ensures isocapnia. The further slowing of the dynamics of the ventilatory response in hyperoxia as well as the preserved isocapnia in hypoxia after beta-blockade argue against any major role of beta-adrenergic mechanisms for these functions of the arterial chemoreceptors. The observed effects are considered to be secondary to the reduced cardiac output and an increased CO2 storage initially during exercise following beta-adrenergic blockade.

2-Deoxyglucose-induced vasodilation and hyperpolarization in rat coronary artery are reversed by glibenclamide.

The mechanisms responsible for coronary vasodilation during ischemia or hypoxia are poorly understood. It has recently been suggested that alterations in intracellular ATP may play a role in this response. We examined whether dilation of isolated coronary arteries in response to metabolic blockade by 2-deoxyglucose, which competitively inhibits glycolysis and glycogenolysis, was sensitive to glibenclamide, an inhibitor of ATP-sensitive potassium channels. Pressurized rat coronary arteries with myogenic tone dilated in response to 2-deoxyglucose by an endothelium-independent mechanism. The dilation was accompanied by a substantial hyperpolarization. Addition of glibenclamide partially reversed this vasodilation and abolished the hyperpolarization. We propose that ATP-sensitive potassium channels play a significant role in the dilator response to 2-deoxyglucose. This may have implications both for ischemia-induced coronary vasodilation and for the use of oral hypoglycemic agents in general.

Cardiac metabolism during exercise in healthy volunteers measured by 31P magnetic resonance spectroscopy.

A technique was devised for individuals to exercise prone in a magnet during magnetic resonance spectroscopy of the heart and phosphorus-31 magnetic resonance spectra of the heart were obtained by the phase modulated rotating frame imaging technique in six healthy volunteers during steady state dynamic quadriceps exercise. During prone exercise heart rate, blood pressure, and total body oxygen consumption were measured at increasing loads and the results were compared with those during Bruce protocol treadmill exercise. During prone exercise with a 5 kg load the heart rate was similar and the systolic and diastolic blood pressures were higher than those during stage 1 of the Bruce protocol. The rate-pressure products were similar but the total body oxygen consumption was lower during prone exercise. There was no difference in the ratio of phosphocreatine to adenosine triphosphate during rest and exercise.Thus during exercise that produced a local cardiac stress equal to or greater than that during stage 1 of the Bruce protocol treadmill exercise, the energy requirements of the normal human myocardium were adequately supplied by oxidative phosphorylation.

Electrocardiogram monitoring at rest and during exercise in 31P magnetic resonance spectroscopy studies of the human heart at 1.9 tesla.

An electrocardiogram (ECG) monitoring system has been developed and evaluated in normal volunteers (n = 7) and patients with various cardiac diseases (n = 24) in a 1.9 tesla magnet during magnetic resonance spectroscopy studies. To minimize an ECG signal path, and thus to reduce motion-related artifacts on the ECG during a dynamic exercise test, one coaxial cable was used to obtain the ECG signal from two electrodes placed parallel to the longitudinal body axis on the left side of the chest. A fiber optic link and an inductor-capacitor low-pass filter were used to remove extraneous radiofrequency (RF) noise and RF pulse artifacts respectively, and the examination bed was solidly supported on the base of the magnet. The ECG monitoring system provided a useful means for continuous recording of the ECG independently of the R-R interval in the high magnetic field, and permitted reliable monitoring of the QRS complex of the subject at rest and during exercise.