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Clinically Relevant Functional Neuroanatomy IV: Neuroanatomy of Memory. Russell M. Bauer, Ph.D. University of Florida AACN 5 th Annual Conference June 8, 2007. Anatomy of Memory. Russell M. Bauer, Ph.D. (DON’T BELIEVE HIS LIES). Multiple Forms of Memory. “Core” Features of Amnesia.
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Clinically Relevant Functional Neuroanatomy IV: Neuroanatomy of Memory Russell M. Bauer, Ph.D. University of Florida AACN 5th Annual Conference June 8, 2007
Anatomy of Memory Russell M. Bauer, Ph.D. (DON’T BELIEVE HIS LIES)
“Core” Features of Amnesia • anterograde amnesia:defect in new learning • retrograde amnesia/remote memory disturbance: defect in retrieving old memories • spared memory abilities:attention span, psychometric intelligence, and ‘nondeclarative’ forms of memory are generally spared
The Human Amnesic Syndrome • Impaired new learning (anterograde amnesia), exacerbated by increasing retention delay • Impaired recollection of events learned prior to onset of amnesia (retrograde amnesia), often in temporally graded fashion • Not limited to one sensory modality or type of material • Normal IQ, attention span, “nondeclarative” forms of memory
Clinically Relevant Dimensions of Human Memory Performance Immediate-recent-remote Encoding-storage-retrieval Material, modality specificity Tests vs. processes
Encoding • Definition: process of transforming to-be remembered in formation into memorable and retrievable form • Encoding I: bringing information-processing capacity to bear on stimuli • Encoding II: ability to use the results of E-1 mnemonically • Relevance: levels-of-processing accounts of memory (memory as by-product of information processing) • Clinical manifestation: poor immediate (superspan) recall
Consolidation/Storage • definition:process of making new memories permanent • basis:anatomic and physiological changes at cellular level; hippocampalsystem important • when?during study-test interval • duration:hours? days? years? • clinical symptom:delayed memory << immediate memory (forgetting)
Performance on a test of memory for news stories. From Squire & Bayley, Curr Opin Neurobiol, 2007, 17, 185-196.
Retrieval • definition:process of locating, selecting, and activating a memory representation • basis: re-enactment of pattern of excitation occurring at encoding • when? at point of test • clinical symptom: recall << recognition (also true of shallow encoding), inconsistent errors
Medial Temporal Syndromes • Anoxic-hypoxic syndromes • cardiac arrest • CO poisoning • Amnesia associated with ECT • CNS Infections (Herpes) • MTS and complex-partial epilepsy(material-specific) • Early AD
Temporal Lobe Pathology Associated with Herpes Simplex Encephalitis
FLAIR (Fluid Attenuated Inversion Recovery) in Medial Temporal Sclerosis
IntegratedCircuitry Linking Temporal, Diencephalic, and Basal Forebrain Regions
Two Limbic Circuits Anterior Thalamus Dorsomedial Thalamus Mamillothalamic Tract Mammilary Bodies Cingulate Gyrus Orbitofrontal Amygdalofugal pathways Fornix Uncus Hippocampus Amygdala Lateral Medial (Papez)
CA3 CA1 DG subic
Delayed Nonmatching to Sample, multiple trials, trial-unique objects
6-8 weeks postsurgery 2 years postsurgery
Murray & Richmond, Curr Opin Neurobiol, 2001 -perirhinal cortex obviously important in memory, but also has many additional connections
Two Limbic Circuits and the Two-system theory of amnesia Anterior Thalamus Dorsomedial Thalamus Mamillothalamic Tract Mammilary Bodies Cingulate Gyrus Orbitofrontal Amygdalofugal pathways Fornix Uncus Hippocampus Amygdala PRPH Lateral Medial (Papez)
Hippocampus is important in specific types of relational memory (e.g., transitive inference)
Morris Water Maze Lesioned rats Sham operated rats (Eichenbaum, et al, 1990) Aged rats Time to Target Young rats (Gallagher, et al, 1993)
Hippocampus v. Entorhinal Cortex Lesions and “Reference” vs. “Working” Memory MWM “Reference Memory (H<ECo) “Working Memory (H=Eco=Sub<Sham) Galani, et al., Behav Brain Res, 1998, 96, 1-12.
Two Limbic Circuits and the Two-system theory of amnesia Anterior Thalamus Dorsomedial Thalamus Mamillothalamic Tract Mammilary Bodies Cingulate Gyrus Orbitofrontal Amygdalofugal pathways Fornix Uncus Hippocampus Amygdala PRPH Lateral Medial (Papez)
IntegratedCircuitry Linking Temporal, Diencephalic, and Basal Forebrain Regions
Diencephalic Syndromes • Korsakoff Syndromeassociated with ETOH abuse or malabsorption • prominent encoding deficits • role of frontal pathology • Vascular disease • Thalamic trauma