Most Helpful Customer Reviews
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3.0 out of 5 stars
"How the Sea Horse (Hippocampus) Facilitates LTM", November 23, 2005
"Memory, Amnesia, & The Hippocampal System", N. Cohen, H. Eichenbaum, MA, MIT Press, 1993/4 ISBN 0-262-03203-1, SC, 330 pg. plus 2 pg. Cont., 4 pg. Pref., 13 Chaps., 4 pg. Notes, 32 pg. Ref., 4 pg. Index. 9" x 6 3/4"
A technical book offering "a high-level theory" derived from animal & human studies on declarative memory mechanisms with especial reference to the hippocampus (Sea Horse or Sea Monster), orchestrating brain's functional hardware (architecture) with instantiated memory. Authors posited the role of hippocampus in memory & defined memory impairment(s) in amnesia(s) to provide a better understanding of normal memory (how we learn, remember & forget).
The mainstay of the book & thesis is generated from an oft-quoted
& well published case of H.M. who at age 27, in 1953 underwent bilateral resection of the hippocampal formation (including the amygdala & mulimodal association areas of the temporal cortex) to relieve major bi-temporal lobe seizures of 10 years duration consequent to bicycle accident at age 9 (H.M. was a pedestrian).
The useful but brief sketching of memories is made with distinctions between declarative vs procedural, semantic vs episodic, & explicit vs implicit & a description of "mediational" or "evaluative" memories. We are provided micro-photographs of human & animal hippocampi; cartoons of hippocampi neuronal cell firings; & etiologies of amnesias, both hippocampal & those non-hippocampal (Korsakoff's, AD, PD, & Huntington's), in declarative memory domain. Discussion is provided on "Place Cell" pyramidal cell firings during spatial exploration, & on Place Fields, an abstract spatial "think"(or thought) of position
(not sensory).
Of interest was discussion of Tower of Hanoi puzzle, cognition of Fibonacci sequencing. mirror & mirror-reversed text studies, & acknowledgement of Morton's memory representations of linguistic objects as "logogens" and visual objects as "pictogens" for memory refreshing. Authors conclude the hippocampus "apparently" stores temporary representations permitting later access or reconstructions (recall) of declarative memory -- that the permanment representation (memory) resides in the neocortex, & that the hippocampus network fashions a "memory space" for the encoding & updating of relations of fresh items -- i.e., the reinstantiations which "enable memory consolidation." Authors share mixed thoughts about renaming procedural memory as that of nondeclarative memory as overly phenomenological rather that representational.
A wordy, overly-pontifical written book by two knowledgeable researchers is interesting to read but harder to digest. Those interested in this & related subjects would be better served wtih "Principles of Neural Science", 4th Ed. 2000 by Kandell, Schwartz & Jessell (1,414 pg.).
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2 of 4 people found the following review helpful:
5.0 out of 5 stars
I forget (do I?), November 26, 2000
This reference is readable and suitable for the interested general reader. While an introductory cognitive science or psychology textbook covers a broader range of material, this reference, restricted to limited aspects of memory, has the advantage of giving the reader a better feel for different approaches (cognitive scientific, psychological, neuroanatomical, physiological, and neuropsychological) towards an understanding of brain functions. 'Procedural memory' optimizes various processors throughout the brain for the stimuli they encounter. 'Declarative memory', dependent on the hippocampal system, is a relational representation of learning experiences, is very accessible and can be easily expressed, and binds outputs of the various neocortical processor outputs (eg, high level visual, auditory, limbic, somesthetic, etc) and olfactory outputs converging on the hippocampal system. Olfactory, frontal, parietal and temporal cortical areas send projections to the superficial entorhinal cortex. In turn, from the entorhinal cortex, the perforant pathway projects to the dentate gyrus (where there are association fibers between neurons), which in turn projects mossy fibers to the CA3 hippocampal region (where there are association fibers between neurons), which in turn projects Schaffer collaterals to the CA1 hippocampal region (which also receives a more direct input from the entorhinal cortex) which then projects to the deep entorhinal cortex, which in turn projects back to the source olfactory, frontal, parietal and temporal cortical areas. The hippocampal subiculum also receives projections from both the CA1 region and the entorhinal cortex, and also projects to the deep entorhinal cortex which then in turn projects back to the cortical areas from which the hippocampal system received projections from. The fornix pathway connects the hippocampal system with subcortical structures such as thalamus, hypothalamus and brainstem nuclei. Glutamate NMDA and non-NMDA neurotransmitter receptors on the same dendritic spines of hippocampal neurons provide a conjunction mechanism - the NMDA channel will open if neurotransmitter is received AND there is sufficient membrane depolarization (ie, in response to another input), and will result in long-term potentiation LTP. However, it is noted that in particular, LTP is best induced if there are high frequency bursts of the stimuli, repetition of these bursts at frequencies corresponding to the theta rhythm, and activation of hippocampal neurons at the peak of the dentate theta rhythm. Electrophysiological recordings of rodent CA1 neurons show that hippocampal neurons encode relationships between environmental and internal cues, in particular, being sensitive to specific locations in the environment during spatial explorations. While the hippocampal system binds together outputs of many neocortical (and olfactory and subcortical) processors and thus allows declarative memories to be reconstructed from features in these processors, the hippocampal system is not the permanent storage site of such memories. For example, in cases of hippocampal system damage, remote memories are not strongly affected. It is thus proposed that the hippocampal system allows access to the various processors so that features of declarative memories can somehow be bound together in a more permanent manner.
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