Introductory Infomations concerning Amnesia  

1. What is Amnesia - a short defintion und explanation of
   Prof. H.J. Markowitsch
2. Forms of Amnesia and Associated Illness
3. What can be done against the symptoms of Amnesia?
4. Frequently Asked Questions: some interesting questions and answers concerning the topic Amnesia...

I. What is Amnesia? (by PROF H.J. Markowitsch)
While Mnemosyne, the Greek muse of memory, represents the healthy ability to remember, amnesia stands for the opposite or the loss of memory. In earlier times, amnesia was regarded as the general inability to encode new and recall old information (“global amnesia“); nowadays, amnesia is considered to be a much more differentiated condition, partly as a consequence of the present dividing of memory into several subsystems (Tulving/Markowitsch 1998).

It is differentiated into domain-, material- and modality-specific amnesias, into memory loss, referring to the future (anterograde amnesia, disturbed ability to form new memories) or to the past (retrograde amnesia; disturbed ability to remember), into partial and global, time-limited (”transient global amnesia“) and unlimited amnesia with respect to time, into amnesia with respect to short-term or long-term memory as well as into organic and functional amnesias (Markowitsch 2002).

In former times, amnesia referred to the complete inability to retrieve information + or to learn information anew, nowadays the term amnesia is used as well when the memory disturbance is incomplete. Weakness of learning, forgetfulness, retrieval loss, spontaneous decay, errorful reproduction, interference-based forgetting, confusional forgetting, motivated forgetting, tip-of-the-tongue phenomena, memory blocks and confabulations belong to the more peripheral amnesic conditions. Generally, amnesias refer to disturbances of long term memory; there are, however, single cases of severe short-term memory disturbances with preserved long term memory (Markowitsch et al. 1999). Amnesic conditions are different from dementias due to their selectivity: In dementia further dimensions of the personality are disturbed, while in amnesic patients generally memory only, but not intelligence or other personality variables are affected. Amnesias with a direct organic background are caused by various forms of brain damage, while so called functional amnesias are caused by psychic traumata or stressful situations. Sometimes a mixture of both forms exists in that way that minor somatic disturbances (which are in principal non-typical for enduring memory disturbances) may lead to lasting amnesic conditions (Markowitsch 1999).

Corresponding to the multitude of amnesias the underlying brain damage or functional interruptions may be quite diverse and may affect both cortical and subcortical regions. Structures of the limbic system are as bottleneck structures (Markowitsch 2000) primarily important for information encoding, while structures of the frontal lobe and the anterior temporal lobes are central for recall (Markowitsch 1999).

In this relation the right-hemispheric combination of these two regions seems to be relevant for recalling the personal past, that is episodic memory, while the same regional combination of the left hemisphere is centrally engaged in the recall from semantic facts (Markowitsch 1999). Is procedural memory disturbed, damage in the basal ganglia and in part also of the cerebellum is assumed to exist. Disturbances of the priming form of memory are usually cortical in nature. The following table provides a survey of those different forms of amnesia.

Markowitsch, H.J. (2000) Memory and amnesia. In: M.-M. Mesulam (Ed.), Principles of Cognitive and Behavioral Neurology, New York: Oxford Univ. Press, pp. 257-293; Markowitsch, H.J. (2002) Dem Gedächtnis auf der Spur. Darmstadt: Primus Verlag; H. J. Markowitsch/E. Kalbe/J. Kessler/H.-M. von Stockhausen/M. Ghaemi/W.-D. Heiss (1999) Short-term memory deficit after focal parietal damage. Journal of Clinical and Experimental Neuropsychology, 25, 784-796; E. Tulving/H. J. Markowitsch (1998) Episodic and declarative memory: Role of the hippocampus. Hippocampus, 8, 198-204; Markowitsch, H.J. (Ed.) (1990) Transient Global Amnesia and Related Disorders. Toronto: Huber Press.