Biology subjects

Janina D Ferbinteanu

Publications and source records attributed to Janina D Ferbinteanu.

2 recordsLinked to original sources

bioRxiv2016

Graph analysis of structural brain networks in Alzheimer’s disease

BackgroundChanges in brain connectivity in patients with early Alzheimers disease (AD) have been investigated using graph analysis. However, these studies were based on small data sets, explored a limited range of network parameters, and did not focus on more restricted sub-networks, where neurodegenerative processes may introduce more prominent alterations.\n\nMethodsIn this study, we constructed structural brain networks out of 87 regions by using data from 135 healthy elders and 100 early AD patients selected from the Open Access Series of Imaging Studies (OASIS) database. We evaluated the graph properties of these networks by investigating metrics of network efficiency, small world properties, segregation, product measures of complexity, and entropy. Because degenerative processes take place at different rates in different brain areas, analysis restricted to sub-networks may reveal changes otherwise undetected. Therefore, we first analyzed the graph properties of a network encompassing all brain areas considered together, and then repeated the analysis after dividing the brain areas into two sub-networks constructed by applying a clustering algorithm.\n\nResultsAt the level of large scale network, the analysis did not reveal differences between AD patients and controls. In contrast, the same analysis performed on the two sub-networks revealed modifications accompanying AD. Changes in small world properties suggested that the ability to engage concomitantly in integration and segregation of information diminished with AD in the sub-network containing the areas of medial temporal lobe known to be heaviest and earliest affected. In contrast, we found that the second network showed an increase in small world propensity, a novel metric that unbiasedly quantifies small world structure. Complexity and entropy measures indicated that the intricacy of connection patterns and structural diversity decreased in both sub-networks.\n\nConclusionsThese results show that neurodegenerative processes impact volumetric networks in a non-global fashion. Our findings provide new quantitative insights into topological principles of structural brain networks and their modifications during early stages of Alzheimers disease.

Bioinformatics↗

bioRxiv2016

Contributions of hippocampus and striatum to memory-guided behavior depend on past experience

The hippocampal and striatal memory systems operate independently and in parallel in supporting spatial and response learning, respectively, when animals are explicitly trained in one task. Here, we investigated whether this principle continues to hold when animals are concurrently trained in two types of tasks. Rats were trained on a plus maze in either a spatial navigation or a cue response task (individual training), while a third set of rats acquired both (concurrent training). Subsequently, the rats underwent either sham surgery or neurotoxic lesions of the hippocampus (HPC), medial dorsal striatum (DSM) or lateral dorsal striatum (DSL), followed by retention testing. Finally, rats in the individual training condition also acquired the novel other task. When rats learned one task, HPC and DSL selectively supported spatial navigation cue response, respectively. However, when rats learned both tasks, HPC and DSL additionally supported the behavior incongruent with the processing style of the corresponding memory system. DSM significantly contributed to performance regardless of task or training procedure. Experience with the cue response task facilitated subsequent spatial learning, while experience with spatial navigation delayed both simultaneous and subsequent response learning. These findings suggest that multiple principles govern the interactions among memory systems.\n\nSignificance StatementCurrently, we distinguish among several types of memories, each supported by a distinct neural circuit. The memory systems are thought to operate independently and in parallel. Here, we demonstrate that the hippocampus and the dorsal striatum memory systems indeed operate independently and in parallel when rats learn one type of task at a time, but interact co-operatively and in synergism when rats concurrently learn two types of tasks. Furthermore, new learning is modulated by past experiences. These results can be explained by a model in which independent and parallel information processing that occurs in the separate memory-related neural circuits is supplemented by information transfer between the memory systems at the level of the cortex.

Animal Behavior and Cognition↗