The investigation of the Neuroanatomical substrates of different memory systems in light of individual differences

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dc.contributor.author Ünal, Çağrı Temuçin
dc.date.accessioned 2019-07-26T10:26:16Z
dc.date.available 2019-07-26T10:26:16Z
dc.date.issued 2018
dc.identifier.uri http://hdl.handle.net/20.500.12485/499
dc.description Devam ediyor en_US
dc.description.abstract Multiple memory systems (MMS) hypothesis suggests that memory is not a single entity. According to this hypothesis, environmental information is differentially encoded in different brain regions. This differential encoding allows organisms to adopt different cognitive and behavioral strategies depending on the intrinsic brain states, environmental factors, and past experience. The engagement of these parallel systems is not necessarily mutually exclusive with the net output being determined by their cooperative and competitive interactions yielding an average of neural activity to be conveyed to motor output structures. The two most well-known of these systems depend on the hippocampus and dorsal striatum and coarsely represent the formation of cognitive maps (i.e. explicit memories) and stimulus-response associations (i.e. implicit memories) respectively. The relative contribution of these two systems during behavior depends on experience (i.e. overtraining increases the contribution of dorsal striatum, hence, with overtraining, habit formation takes over cognitive maps) and individual differences (i.e. relative dependence on hippocampus and dorsal striatum during behavior changes from individual to individual). While certain neurodegenerative disorders like Alzheimer’s disease and Parkinson’s disease can bias individuals to heavily depend on a set of structures and hence strategies over the others, the neurobiological substrates of individual differences in healthy individuals are not known at the cellular and network levels. The proposed sets of experiments aim to identify the neurobiological substrates underlying individual differences by using behavioral and anatomical tools in rodents. The emerging neuroanatomical data will be tested to test computational models that attempt to elucidate memory system interactions. Specifically, these studies will constitute the first studies characterizing stable anatomical characteristics at the cellular level that determine individual differences in the relative contribution of different memory systems. The MMS theory forms the basis of the proposed experiments. Briefly, rats will be tested on an ambiguous t-maze where two distinct solutions (an allo-centric solution through hippocampus vs. an ego-centric solution through the dorsal striatum) will be available to solve the spatial problem. Previous research reveal a dichotomy in animals that cannot be explained by chance factor (explained in the main body of the text). Following the behavioral phenotyping of the animals, we will run a series of anatomical procedures and analysis. Allo-centric and ego-centric learners as characterized in a t-maze will be compared with respect to: 1- Number of cholinergic neurons that project to the hippocampus (medial septal neurons) and dorsal striatum (striatal cholinergic interneurons) 2- Number of dopaminergic neurons that project to the hippocampus (ventral tegmental area dopaminergic neurons) and dorsal striatum (substantia nigra dopamine neurons). 3- Morphological characteristics of the neurons mentioned in “1” and “2” 4- Cell counts in the dorsal striatum and hippocampus These comparisons will in turn be used to test pre-existing models pertaining to memory system interactions. The results will contribute to our overall understanding of the organization of structures that play crucial roles in memory formation. As mentioned before, certain neurodegenerative disorders selectively impair (and/or enhance) different types of memory systems. The understanding of individual differences in this respect will contribute to the elucidation of the pathological mechanisms underlying age related memory impairments. Given the exponential growth of the aging population, an understanding of age-related disorders is crucial for developing treatment strategies for these disorders along with the development of rehabilitative measures. The results are expected to contribute to the improvement of life in elderly, promoting their participation in daily activities, a factor crucial for our society’s socio-economic growth. en_US
dc.description.sponsorship TUBITAK 3501 en_US
dc.language.iso en en_US
dc.subject Psychology en_US
dc.title The investigation of the Neuroanatomical substrates of different memory systems in light of individual differences en_US
dc.type Project-TUBITAK en_US

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