Memory and the Brain: Neuroanatomical and Functional Imaging Correlates
of Memory and Memory Disorders
Hans Markowitsch
University of Bielefeld
Prerequisites: Read at least on my chapters on
memory and amnesia given below.
Course Description:
Memory nowadays is divided according to time and contents.
Along the dimension time it is distinguished between short-term or on-line
memory (“working memory”) and long-term memory, with short-term memory lasting
from seconds to minutes and long-term memory referring to everything of longer
duration. With respect to contents, there are three main directions: A few
people consider memory to be a unitary system. Most scientists divide memory
into several systems. A second approach is associated with the name of Larry
Squire (“declarative and non-declarative forms of memory”), and the third
with that of Endel Tulving (“episodic and semantic memory systems as well
as 3 other forms”). Tulving and Markowitsch at present divide memory into
five systems and suggest different anatomical networks for each of these
systems. Furthermore, they consider it possible to arrange them hierarchically.
The most complex memory system is the episodic-autobiographical one which
requires self-conscious reflection and is embedded in the dimensions of
time and locus. It frequently is affect-related and allows mental time traveling.
Semantic memory, on the other hand, is context-free fact memory. On the
more automatic, implicit level, perceptual memory, procedural memory and
the priming system constitute the other three long-term memory systems with
perceptual memory allowing the assessment of novelty/familiarity of perceptual
stimuli, procedural memory referring largely to sensory-motor skills and
simple conditioning and priming to an enhanced identification of objects.
On the brain level, working memory recruits prefrontal and (left) parietal
structures. For information acquisition, episodic and – though to a much
lesser degree – semantic memory engage limbic structures and portions of
the prefrontal cortex, while perceptual memory and priming are principally
a matter of poly- and unimodal neocortical regions, and procedural memory
one of the basal ganglia, possibly of cortical premotor regions and cerebellar
structures. For the last three memory systems, information storage and information
retrieval engage the same structures necessary for acquisition or encoding,
while for the episodic and memory systems the situation is more complex.
Both of these are represented in neocortical nets, the episodic memory system
furthermore possibly recruits limbic structures. There seems to be a preponderance
of right-hemispheric nets for episodic and of left-hemispheric ones for semantic
memories. Similarly, episodic information retrieval is triggered via right-hemispheric
prefrontal and anterior structures, while semantic memory retrieval activates
the same net of the left hemisphere.
These networks for information processing have been established on the
basis of both patient data and data in normal subjects using functional
imaging methods. Our own research centers on studying patients with focal
neurological damage who have major forms of episodic anterograde and/or
retrograde amnesia, on studying the processing of autobiographical memory
in normals subjects with positron emission tomography and functional magnetic
resonance imaging. Recent interesting features of this work include differing
brain networks engaged in old versus more recent autobiographical memories,
different anatomical representations of memories with a positive (“happy”)
and negative (“sad”) emotional background. Furthermore, our recent research
demonstrates that in part similar brain regions appear metabolically suppressed
in patients with socalled non-organic, that is, psychiatric or psychogenic
amnesias. For these, an increased release of stress hormones is seen as basis
for what can be termed a mnestic block syndrome. It will be discussed whether
the results of modern functional imaging methods allow to bridge the gap
between patients with manifest organic brain tissue damage and patients with
“functional” amnesia induced by psychic stress or trauma conditions.
Course Reading List
Markowitsch, H.J. (2000). Memory and amnesia. In M.-M. Mesulam
(Ed.), Principles of cognitive and behavioral neurology (pp. 257-293). New
York: Oxford University Press.
Markowitsch, H.J. (2000). Neuroanatomy of memory. In E. Tulving & F.I.M.
Craik (Eds.), The Oxford handbook of memory (pp. 465-484). New York: Oxford
University Press.
Markowitsch, H.J. (2000). Anatomical bases of memory disorders. In M.S.
Gazzaniga (Ed.), The new cognitive neurosciences (2nd ed.). (pp. 781-795).
Cambridge, MA: MIT Press.
Markowitsch, H.J. (2003). Autonoëtic consciousness. In A.S. David
& T. Kircher (Eds.), The self and schizophrenia: A neuropsychological
perspective (in press). Cambridge: Cambridge University Press.
Fink, G.R., Markowitsch, H.J., Reinkemeier, M., Bruckbauer, T., Kessler,
J. & Heiss, W.-D. (1996). Cerebral representation of one’s own past:
neural networks involved in autobiographical memory. Journal of Neuroscience,
16, 4275-4282.
Markowitsch, H.J. (1996). Organic and psychogenic retrograde amnesia: two
sides of the same coin? Neurocase, 2, 357-371.
Markowitsch, H.J. (1999). Functional neuroimaging correlates of functional
amnesia. Memory, 7, 561-583.
Markowitsch, H.J., Kessler, J., Weber-Luxenburger, G. , Van der Ven, C.
& Heiss, W.-D. (2000). Neuroimaging and behavioral correlates of recovery
from ‘mnestic block syndrome’ and other cognitive deteriorations. Neuropsychiatry,
Neuropsychology, and Behavioral Neurology, 13, 60-66.
Markowitsch, H.J. (2002). Functional retrograde amnesia – mnestic block
syndrome. Cortex, 38, 651-654.
Piefke, M., Weiss, P.H., Zilles, K., Markowitsch, H.J. & Fink, G.R.
(2003). Differential remoteness and emotional tone modulate the neural correlates
of autobiographical memory. Brain, in press.