Advertisement

Nature of the Functional Loss in Amnesia: Possible Role for a Highly Structured Neural Network

  • Andrew Mayes
Conference paper
Part of the Perspectives in Neural Computing book series (PERSPECT.NEURAL)

Abstract

Organic amnesia is a condition in which brain damage to structures in the medial temporal lobes, midline diencephalon or basal forebrain impairs the ability to recall or recognize recently experienced facts or episodes (anterograde amnesia) and also the ability to recall and recognize facts and episodes, memories for which may have been formed normally up to decades before the onset of brain damage. Despite these impairments, which can be very severe in some patients, many amnesics show preserved intelligence and short-term memory. Amnesics therefore show an impairment that is specific to certain kinds of memory, leaving other kinds of memory and cognitive function intact. In this paper, the precise nature of the preserved and impaired functions will first be described in more detail in order to facilitate an appropriate characterization of the disturbed function(s) and to help determine whether patients are suffering from only one functional deficit or several independent functional deficits. Work that is concerned with identifying the structures, damage to which is critical in producing the syndrome, will then be briefly reviewed. The anatomy and physiology of the critical structures will then be outlined and the nature of their informational inputs and outputs briefly considered. Finally, the conditions that must be met by a neural network model that can produce the kinds of memory that are deficient in amnesics will be discussed.

Keywords

Entorhinal Cortex Basal Forebrain Medial Temporal Lobe Retrograde Amnesia Association Cortex 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Daum I, Channon S and Canavan AGM (1989) Classical conditioning in patients with severe memory problems. Journal of Neurology, Neurosurgery and Psychiatry 52: 47–51.Google Scholar
  2. Dudai Y (1989) The Neurobiology of Memory:Concepts. Findings and Trends. Oxford University Press, Oxford.Google Scholar
  3. Heit G, Smith ME and Halgren E (1988) Neuronal encoding of individual words and faces by the human hippocampus. Nature 333: 773–775.CrossRefGoogle Scholar
  4. Hirst W, Johnson MK, Kim JK, Phelps EA, Risse G and Volpe BT (1986) Recognition and recall in amnesics. Journal of Experimental Psychology: Learning, Memory and Cognition 12: 445–451.Google Scholar
  5. Hirst W, Johnson MK, Phelps EA and Volpe BT (1988) More on recognition and recall with amnesics. Journal of Experimental Psychology: Learning, Memory and Cognition 14: 758–762.Google Scholar
  6. Jacoby LL and Witherspoon D (1982) Remembering without awareness. Canadian Journal of Psychology 36: 300–324.CrossRefGoogle Scholar
  7. Lye RH, O’Boyle DJ, Ramsden RT and Schady W (1988) Effects of a unilateral cerebellar lesion on the acquisition of eye-blink conditioning in man. Journal of Physiology 403: 58 P.Google Scholar
  8. McClelland JL and Rumelhart DE (1986) Amnesia and distributed memory. In:McClelland JL, Rumelhart DE and the PDP Research Group (eds) Parallel Distributed Processing, volume 2: Psychological and Biological Models. MIT Press, Cambridge, Mass.Google Scholar
  9. Mayes AR (1988) Human Organic Memory Disorders. Cambridge University Press, New York.CrossRefGoogle Scholar
  10. Mayes AR, Meudell PR, Mann D and Pickering A (1988) Location of lesions in Korsakoff’s syndrome:neuropsychological and neuropathalogical data on two patients. Cortex 24: 1–22.Google Scholar
  11. Mishkin M and Appenzeller T (1987) The anatomy of memory. Scientific American 256: 62–71.CrossRefGoogle Scholar
  12. Mishkin M, Malamut B and Bachevalier J (1984) Memories and habits:two neural systems. In:Lynch G, McGaugh JL and Weinberger NM (eds) Neurobiology of Learning and Memory. Guildford Press, New York.Google Scholar
  13. Morris RGM (1989a) Does synaptic plasticity play a role in information storage in the vertebrate brain. In:Monis RGM (ed) Parallel Distributed Processing:Implications for Psychology and Neurobiology. Oxford University Press, Oxford.Google Scholar
  14. Morris RGM (1989b) Introductionxomputational neuroscience:modelling the brain. In:Morris RGM (ed) Parallel Distributed Processing:Implications for Psychology and Neurobiology. Oxford University Press, Oxford.Google Scholar
  15. Press GA, Amaral DG and Squire LR (1989) Hippocampal abnormalities in amnesic patients revealed by high-resolution magnetic resonance imaging. Nature 341: 54–57.CrossRefGoogle Scholar
  16. Rolls ET (1989) Parallel distributed processing in the brain:implications of the functional architecture of neuronal networks in the hippocampus. In:Morris RGM (ed) Parallel Distributed Processing:Implications for Psychology and Neurobiology. Oxford University Press, Oxford.Google Scholar
  17. Schacter DL (1990) Toward a cognitive neuropsychology of awareness:implicit knowledge and anosognosia. Journal of Clinical and Experimental Neuropsychology 12: 155–178.CrossRefGoogle Scholar
  18. Shimamura AP (1989) Disorders of memory:the cognitive science perspective. In:Boller F and Grafman J (eds) Handbook of Neuropsychology, volume 3. Elsevier, Amsterdam.Google Scholar
  19. Shoqeirat MA (1989) Contextual memory deficits and rate of forgetting in amnesics with different aetiologies. Unpublished Ph.D. thesis, Manchester University. Singer W (1990) Mechanisms of use-dependent synaptic plasticity in visual cortex. Paper given at the Open Network Conference on Neural Mechanisms of Learning and Memory. London, 3–6 April.Google Scholar
  20. Squire LR, Haist F and Shimamura AP (1989) The neurology of memory:quantitative assessment of retrograde amnesia in two groups of amnesic patients. Journal of Neuroscience 9: 828–839.Google Scholar
  21. Squire LR, Shimamura AP and Amaral DG (1989) Memory and the hippocampus. In:Byrne J and Berry W (eds) Neural Models of Plasticity. Academic Press, New York.Google Scholar
  22. Zola-Morgan S, Squire LR and Amaral DG (1986) Human amnesia and the medial temporal region:enduring memory impairment following a bilateral lesion limited to field CA1 of the hippocampus. Journal of Neuroscience 6: 2950–2967.Google Scholar
  23. Zola-Morgan S, Squire LR and Amaral DG (1989) Lesions of the amygdala that spare adjacent cortical regions do not impair memory or exacerbate the impairment following lesions of the hippocampal formation. Journal of Neuroscience 9: 1922–1936.Google Scholar
  24. Zola-Morgan S, Squire LR, Amaral DG and Suzuki WA (1989) Lesions of perirhinal and parahippocampal cortex that spared the amygdala and hippocampal formation produce severe memory impairment. Journal of Neuroscience 9: 4355–4370.Google Scholar

Copyright information

© Springer-Verlag London Limited 1992

Authors and Affiliations

  • Andrew Mayes

There are no affiliations available

Personalised recommendations