Hippocampal memory encoding and retrieval: Difference between revisions

Revision as of 09:13, 6 July 2016

Revision as of 09:14, 6 July 2016

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===Psychiatric Disorders===

Individuals who develop hippocampal lesions often fare poorly on measures of verbal declarative memory. Tests involving the recall of paragraphs or strings of words, as cited by Bremner and colleagues, illustrate a degree of dysfunction among lesion patients proportionate to the percentage of hippocampal volume and the amount of cells lost.<ref name=f>{{cite journal | last1 = Bremner | first1 = J. | last2 = Vythilingam | first2 = M. | last3 = Vermetten | first3 = E. | last4 = Southwick | first4 = S. | last5 = MaGlashan | first5 = T. | last6 = Nazeer | first6 = A. | last7 = Khan | first7 = S. | last8 = Vaccarino | first8 = V. | last9 = Soufer | first9 = R. | last10 = Garg | first10 = P. | last11 = Chin | first11 = K. | last12 = Staib | first12 = L. | last13 = Duncan | first13 = J. | last14 = Charney | first14 = D. | year = 2003 | title = MRI and PET study of deficits in hippocampal structure and function in women with childhood sexual abuse and posttraumatic stress disorder | url = | journal = The American Journal of Psychiatry | volume = 160 | issue = | pages = 924–932 | doi=10.1176/appi.ajp.160.5.924}}</ref>

As precursors toward later studies that would showcase the effect of [[Post-Traumatic Stress Disorder]] (PTSD) on the human hippocampus, animal studies have broadly demonstrated a susceptibility of the mammalian hippocampus to stressors. In particular, stressed animals develop functional deficits in memory, changes in hippocampal form, and an impairment in neurogenesis, or the ability to produce new neurons.<ref name=f />

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===Disease===

According to the Journal of Neurology, Neurosurgery, and Psychiatry, [[Alzheimer’s]] generally causes a reduction in tissue as well as neurodegeneration throughout the brain. Out of all areas in the brain, the hippocampus is among the first to be damaged by Alzheimer’s. One study located in the Journal of Neurology, Neurosurgery, and Psychiatry tested to see the volume changes of the hippocampus in Alzheimer’s disease patients. Results showed that there was 27% less volume in the hippocampus compared with the hippocampus found in normal cognition. Lastly, the difference between the hippocampus of an Alzheimer’s patient and that of a normal patient was shown through the notable loss seen in cortical grey matter in Alzheimer’s.<ref name=i>{{cite journal | last1 = Du | first1 = A. | last2 = Schuff | first2 = N. | last3 = Amend | first3 = D. | last4 = Laakso | first4 = M. | last5 = Hsu | first5 = Y. | last6 = Jagust | first6 = W. | last7 = Yaffe | first7 = K. | last8 = Kramer | first8 = J. | last9 = Reed | first9 = B. | last10 = Norman | first10 = D. | last11 = Chui | first11 = H. | last12 = Weiner | first12 = M. | year = 2001 | title = Magnetic resonance imaging of the entorhinal cortex and hippocampus in mild cognitive impairment and alzheimer's disease | url = | journal = Journal of Neurology, Neurosurgery, Psychiatry | volume = 71 | issue = | pages = 441–447 | doi=10.1136/jnnp.71.4.441}}</ref>

==Experiment==