Differential functional response in the posteromedial cortices and hippocampus to stimulus repetition during successful memory encoding

The reduction of neural activity in response to repeated stimuli, repetition suppression, is one of the most robust experience‐related cortical dynamics known to cognitive neuroscience. Functional magnetic resonance imaging (fMRI) studies during episodic memory encoding have demonstrated repetition suppression in the hippocampus and this reduction has been linked to successful memory formation. An emerging body of functional imaging evidence suggests that the posteromedial cortex, in addition to the medial temporal lobes, may have a pivotal role in successful episodic memory. This area typically deactivates during initial memory encoding, but its functional changes in response to repetitive encoding remain poorly specified. Here, we investigate the repetition‐related changes in the posteromedial cortex as well as the hippocampus while the participants underwent an fMRI experiment involving repetitive encoding of face–name pairs. During the first encoding trial of face–name pairs, significant activation in the hippocampus was observed. The second and third encoding trials demonstrated a repetition suppression effect in the hippocampus, indicated by a stepwise decrease of activation. In contrast, the posteromedial cortex demonstrated significant deactivation during the initial encoding trial of face–name pairs. The second and third encoding trials demonstrated a stepwise decrease of deactivation, repetition enhancement, with activity at or above baseline levels in the final encoding trial. These findings demonstrate that hippocampus repetition suppression as well as posteromedial repetition enhancement is related to successful encoding processes and are discussed in relation to the default mode hypothesis as well as potential implications for understanding late‐life amnestic disorders. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.     

Zum Sturz ins Wasser

Ohne ZusammenfassungUnsere Ausführungen, die Herrn Geheimrat Prof. Dr.Ungar, dem Altmeister der Gerichtlichen Medizin auf deutschem Sprachgebiete, anläBlich seines 80. Geburtstagsfestes als Zeichen unserer aufrichtigen Verehrung gewidmet werden, bestätigen also vollinhaltlich die auf theoretischem Wege gewonnenen Schlußfolgerungen der in der Einleitung zitierten Abhandlung. Sie liefern aber auch noch — und dies erscheint uns als ihr wesentliches Ergebnis — eine experimentell gefestigte Stütze für unsere durch die Problemstellung bedingte indirekte Beweisführung, die uns jeglichen Zweifel bezüglich der Richtigkeit der Behauptung, daß unter Umständen beim Fall eines Menschen ins Wasser aus großer Höhe selbst Knochenbrüche durch das Aufschlagen des Körpers aufs Wasser entstehen können, benimmt.     

Biofilm formation in an in vitro model of cochlear implants with removable magnets.

BACKGROUND: Cochlear implant (CI) recesses, such as the removable magnet pocket, appear to harbor more biofilm than smooth surfaces. The aim of this study was to examine the impact of removable magnets on biofilm formation in an in vitro model. METHODS: Silastic models were constructed to represent CIs with and without a magnet pocket and with and without a titanium blank in the pocket. CIs were exposed to a culture of a biofilm forming strain of Staphylococcus aureus. Adherence of planktonic bacteria and biofilm formation were assessed with quantitative bacterial counts and scanning electron microscopy. RESULTS: Adherent bacterial counts were significantly higher in CI models with an empty magnet pocket (P = 0.0097). Biofilm formation was significantly lower in CI models without a magnet pocket (P = 0.0121). CONCLUSIONS: CI magnet pockets harbor bacteria that can increase biofilm development in an in vitro model.     

Increased cognitive sensitivity to scopolamine with age and a perspective on the scopolamine model

18 older normal volunteers (mean age = 66.5 ± 7.9 years) and 46 younger volunteers (mean age = 27.0 ± 6.1 years) were administered the anticholinergic drug scopolamine (0.5 mg i.v.) followed by a battery of cognitive tests evaluating attention, learning and memory. The older subjects were significantly more impaired than the younger by scopolamine on some tests of learning and memory. This increased sensitivity of the older group to scopolamine is consistent with studies in animals and humans showing decreased cholinergic system function with age. The findings also indicate that age is an important variable to consider in using the scopolamine model of memory impairment. The cognitive impairment caused by scopolamine in younger subjects in this and prior studies is similar to some, but not all aspects of the impairment which occurs in normal aging^11,29,37. Scopolamine also caused impairments on digit span and word fluency tasks, which are not consistent with normal aging changes. In the older group of subjects, scopolamine produced aspects of the cognitive impairment which occurs in AD on tests of episodic memory and learning, vigilance-attention, category retrieval, digit span, and number of intrusions^64,86,88,91. Other areas of cognition that are of relevence to aging and AD such as psychomotor speed, praxis, concept formation and remote memory were not evaluated in this study. Some of these are being evaluated in ongoing studies, along with additional and more specific tests of retrieval from knowledge memory, implicit memory and attention. The scopolamine model has provided a fruitful pharmacologie starting point for the study of a number of cognitive operations. The idea of dissecting apart aspects of memory systems pharmacologically depends on the availability of neurochemically specific drugs and on the specificity and sensitivity of neuropsychological tests for distinct cognitive operations or domains. Further studies using such tools will aid not only in the understanding of the impairments which occur in aging and in AD, but also of the conceptualization of memory and other cognitive operations and ultimately the physiological mechanisms involved in memory and learning.     

Primary histiocytic lymphoma of the esophagus

Squamous cell carcinoma represents the most common primary malignant lesion of the esophagus (1). The initial manifestation of lymphosarcoma infrequently occurs in the gastrointestinal tract, and in one large series, there were no lymphosarcomas presenting in the esophagus (2). In the case described below, a primary histiocytic lymphoma (large cell lymphoma) was discovered in the distal esophagus.     

Context-specific memory and apolipoprotein E (ApoE) epsilon 4: cognitive evidence from the NIMH prospective study of risk for Alzheimer's disease.

The aim of the study was to determine whether the epsilon 4 allele of the apolipoprotein E (ApoE) gene was associated primarily with context-specific memory among individuals at genetic risk for developing Alzheimer's disease. The effect of ApoE status on comprehensive neuropsychological results was examined in 176 healthy adults during baseline cognitive testing in the NIMH Prospective Study of Biomarkers for Older Controls at Risk for Alzheimer's Disease (NIMH Prospective BIOCARD Study). The presence of the epsilon 4 allele was associated with significantly lower total scores on the Logical Memory II subtest of the Wechsler Memory Scale-Revised and percent of information retained after delay. Further analysis indicated the prose recall and retention effect was partially explained by a small subgroup of epsilon 4 homozygotes, suggesting a gradually progressive process that may be presaged with specific cognitive measures. The current results may represent an epsilon 4-associated breakdown between gist-related information and context-bound veridical recall. This relative disconnection may be understood in light of putative epsilon 4-related preclinical accumulation of Alzheimer pathology (tangles and plaques) in the entorhinal cortex (EC) and among frontal networks, as well as the possibility of less-efficient compensatory strategies.     

A pilot placebo-controlled study of trazodone and buspirone in alzheimer's disease

The pharmacological management of behavioural symptoms in Alzheimer's disease is limited by the dearth of effective agents in this area. The purpose of this study was to determine whether trazodone or buspirone are helpful in the treatment of behavioural disturbance in AD. Ten patients meeting NINCDS criteria for AD with behavioural complications were administered trazodone (up to 50 mg tid), buspirone (10 mg tid), and placeboin a 12-week double-blind, crossover design. Outcome measures were the Brief Psychiatric Rating Scale (BPRS), the Dementia Mood Assessment Scale (DMAS), and the Buschke Selective Reminding Task. The data were analysed by ANOVA. Compared to placebo, trazodone produced a small but significant reduction in BPRS and DMAS scores (p<0.05), indicating improvement in behaviour but no change in cognitive measures. In contrast, buspirone has no significant effect on either behavioural or cognitive measures compared to placebo. The results of this pilot study suggest a beneficial role for trazodone, but not buspirone, in the treatment of behavioural disturbance in AD. Further studies using a wider range of doses of trazodone in more behaviourally disturbed AD patients should now be initiated in an attempt to replicate and expand on this preliminary finding.