The influence of recollection and familiarity in the formation and updating of associative representations

Prior representations affect future learning. Little is known, however, about the effects of recollective or familiarity-based representations on such learning. We investigate the ability to reuse or reassociate elements from recollection- and familiarity-based associations to form new associations. Past neuropsychological research suggests that hippocampal, and presumably recollective, representations are more flexible than extra-hippocampal, presumably familiarity-based, representations. We therefore hypothesize that the elements of recollective associations, as opposed to familiarity-based representations, may be more easily manipulated and decoupled from each other, and facilitate the formation of new associations. To investigate this hypothesis we used the AB/AC learning paradigm. Across two recall studies we observed an advantage in learning AC word pairs if AB word pairs were initially recollected. Furthermore, AB word pairs were more likely to intrude during a final AC test if those AB word pairs were initially familiarity-based. A third experiment using a recognition version of the AB/AC paradigm ruled out the possibility that our findings were due to memory strength. Our results support the idea that elements in recollective associative traces may be more discretely coded, leading to their flexible use, whereas elements in familiarity-based associative traces are less flexible

Impacto del volcanismo y glaciarismo holocénicos en el poblamiento humano de la cordillera sur de Mendoza (Argentina): Una perspectiva geoarqueológica

A prolonged period of decreased human occupation has been proposed for Mendoza Province, provoked by conditions of increasing aridity during the mid-Holocene. It has also been suggested that the systematic human peopling of the high-altitude Andean environments started ca. 2000-1500 years BP, because of a process of economic intensification in lowland areas with higher availability of resources. In this paper, we present the results of a project designed to assess the role of volcanic activity and glacial advances as the main cause for archaeological discontinuities recorded in the archaeological record of the high Andes. This study covers a latitudinal range between 35°-37°S. We present geochemical and chronological results for tephras recorded in archaeological and geological sites, attempting to define the volcanic sources and their impact on the landscape. The analysis includes a geoarchaeological study of the Valenzuela River, which shows the magnitude of the volcanic activity in the Planchón-Peteroa complex, as well as the extent of Holocene glacial processes. The results presented allow suggesting alternative explanation for the temporal sequences of the archaeological record, inasmuch as highlighting the contribution of geoarchaeology

Grey and white matter correlates of recent and remote autobiographical memory retrieval:Insights from the dementias

The capacity to remember self-referential past events relies on the integrity of a distributed neural network. Controversy exists, however, regarding the involvement of specific brain structures for the retrieval of recently experienced versus more distant events. Here, we explored how characteristic patterns of atrophy in neurodegenerative disorders differentially disrupt remote versus recent autobiographical memory. Eleven behavioural-variant frontotemporal dementia, 10 semantic dementia, 15 Alzheimer's disease patients and 14 healthy older Controls completed the Autobiographical Interview. All patient groups displayed significant remote memory impairments relative to Controls. Similarly, recent period retrieval was significantly compromised in behavioural-variant frontotemporal dementia and Alzheimer's disease, yet semantic dementia patients scored in line with Controls. Voxel-based morphometry and diffusion tensor imaging analyses, for all participants combined, were conducted to investigate grey and white matter correlates of remote and recent autobiographical memory retrieval. Neural correlates common to both recent and remote time periods were identified, including the hippocampus, medial prefrontal, and frontopolar cortices, and the forceps minor and left hippocampal portion of the cingulum bundle. Regions exclusively implicated in each time period were also identified. The integrity of the anterior temporal cortices was related to the retrieval of remote memories, whereas the posterior cingulate cortex emerged as a structure significantly associated with recent autobiographical memory retrieval. This study represents the first investigation of the grey and white matter correlates of remote and recent autobiographical memory retrieval in neurodegenerative disorders. Our findings demonstrate the importance of core brain structures, including the medial prefrontal cortex and hippocampus, irrespective of time period, and point towards the contribution of discrete regions in mediating successful retrieval of distant versus recently experienced events

Emerging pharmacotherapy for cancer patients with cognitive dysfunction

Advances in the diagnosis and multi-modality treatment of cancer have increased survival rates for many cancer types leading to an increasing load of long-term sequelae of therapy, including that of cognitive dysfunction. The cytotoxic nature of chemotherapeutic agents may also reduce neurogenesis, a key component of the physiology of memory and cognition, with ramifications for the patient's mood and other cognition disorders. Similarly radiotherapy employed as a therapeutic or prophylactic tool in the treatment of primary or metastatic disease may significantly affect cognition. A number of emerging pharmacotherapies are under investigation for the treatment of cognitive dysfunction experienced by cancer patients. Recent data from clinical trials is reviewed involving the stimulants modafinil and methylphenidate, mood stabiliser lithium, anti-Alzheimer's drugs memantine and donepezil, as well as other agents which are currently being explored within dementia, animal, and cell culture models to evaluate their use in treating cognitive dysfunction

Hippocampal and retrosplenial goal distance coding after long-term consolidation of a real-world environment

Recent research indicates the hippocampus may code the distance to the goal during navigation of newly learned environments. It is unclear however, whether this also pertains to highly familiar environments where extensive systems-level consolidation is thought to have transformed mnemonic representations. Here we recorded fMRI while University College London and imperial College London students navigated virtual simulations of their own familiar campus (> 2 years of exposure) and the other campus learned days before scanning. Posterior hippocampal activity tracked the distance to the goal in the newly learned campus, as well as in familiar environments when the future route contained many turns. By contrast retrosplenial cortex only tracked the distance to the goal in the familiar campus. All of these responses were abolished when participants were guided to their goal by external cues. These results open new avenues of research on navigation and consolidation of spatial information and underscore the notion that the hippocampus continues to play a role in navigation when detailed processing of the environment is needed for navigation

Symptoms in different severity degrees of bruxism: a cross-sectional study

Objective: The aim of the present study was to evaluate symptoms of the muscle pain, sleep quality, oral health, anxiety, stress and depression in individuals with different severity degrees of bruxism. Methods: Seventy-two individuals with bruxism were enrolled in the study, classified into: moderate (n=25) and severe (n=47) bruxism. Pain intensity was assessed using the Visual Analogical Scale, pain threshold with algometer, sleep quality by the Pittsburgh Sleep Quality Index, oral health by the Oral Health Impact Profile, anxiety by the State-Trait Anxiety Inventory, stress by the Perceived Stress Scale and depression using the Beck Depression Inventory. The significance level considered was 5%. Results: The results showed that individuals with severe bruxism presented greater muscle pain intensity, sleep disorder, worse oral health, high anxiety level and dysphoria with statistically significant differences (pObjetivo: Avaliar sintomas de dor muscular, qualidade de sono, saúde bucal, ansiedade, estresse e depressão em indivíduos com diferentes graus de severidade do bruxismo. Métodos: Setenta e dois indivíduos com bruxismo participaram do estudo e foram classificados com bruxismo moderado (n=25) e severo (n=47). A intensidade da dor foi avaliada pela Escala Visual Analógica, limiar de dor com o algômetro, qualidade de sono pelo Índice de Qualidade de Sono de Pittsburgh, saúde bucal pelo Perfil de Impacto de Saúde Bucal, ansiedade pelo Inventário de Ansiedade Traço-Estado, estresse pela Escala de Estresse Percebido e depressão pelo Inventário de Depressão de Beck. O nível de significância considerado foi 5%. Resultados: Os resultados demonstraram que indivíduos com bruxismo severo apresentaram maior intensidade de dor muscular, distúrbio do sono, pior qualidade de saúde bucal, elevado grau de ansiedade e disforia, com diferenças estatisticamente significantes (p;0,05). Conclusão: Os dados sugerem que indivíduos com bruxismo severo tem sintomas mais intensos. Eles apresentam maior intensidade de dor muscular, alterações na qualidade do sono e saúde bucal, ansiedade e depressão do que indivíduos com bruxismo moderado. Porém, ambos apresentam similaridade no estresse.Objetivo: Evaluar los síntomas dolor muscular, calidad de sueño, salud bucal, ansiedad, estrés y depresión en sujetos con diferentes niveles de gravedad del bruxismo. Método: Participaron del estudio 72 personas con bruxismo, clasificado según los niveles moderado (n=25) y grave (n=47). Se evaluaron la intensidad del dolor mediante la Escala Visual Analógica, umbral de dolor con algómetro, la calidad de sueño por el Índice de Calidad de Sueño de Pittsburgh, la salud bucal mediante el Perfil del Impacto de Salud Bucal, la ansiedad por el Inventario de Ansiedad Rasgo-Estado, el estrés mediante la Escala de Estrés Percibido y la depresión por el Inventario de Depresión de Beck. Se consideró el nivel de significación de 5%. Resultados: Los sujetos con bruxismo grave presentaron más intensamente dolor muscular, trastorno de sueño, peor calidad de salud bucal, alto grado de ansiedad y disforia, con diferencias estadísticamente significativas (p;0,05). Conclusión: Los datos mostraron que los sujetos con bruxismo grave sufren síntomas más intensos. A pesar de sufrir síntomas más intensos de dolor muscular, calidad de sueño y salud bucal alterada, ansiedad y depresión que los sujetos con bruxismo moderado, el estrés está presente en los dos niveles de bruxismo

Classic and recent advances in understanding amnesia

Neurological amnesia has been and remains the focus of intense study, motivated by the drive to understand typical and atypical memory function and the underlying brain basis that is involved. There is now a consensus that amnesia associated with hippocampal (and, in many cases, broader medial temporal lobe) damage results in deficits in episodic memory, delayed recall, and recollective experience. However, debate continues regarding the patterns of preservation and impairment across a range of abilities, including semantic memory and learning, delayed recognition, working memory, and imagination. This brief review highlights some of the influential and recent advances in these debates and what they may tell us about the amnesic condition and hippocampal function