The Episodic Memory System: Neurocircuitry and Disorders

  title={The Episodic Memory System: Neurocircuitry and Disorders},
  author={Bradford C. Dickerson and Howard Eichenbaum},
The ability to encode and retrieve our daily personal experiences, called episodic memory, is supported by the circuitry of the medial temporal lobe (MTL), including the hippocampus, which interacts extensively with a number of specific distributed cortical and subcortical structures. In both animals and humans, evidence from anatomical, neuropsychological, and physiological studies indicates that cortical components of this system have key functions in several aspects of perception and… 
Episodic memory in aspects of large-scale brain networks
This review focuses on the functional organization of the MTL and other neocortical areas in episodic memory and shows that brain stimulation may impact memory through modulating functional networks, carrying future implications of a novel interventional therapy for memory impairment.
Characterization of brain network supporting episodic memory in the absence of one medial temporal lobe
The data suggest that hyperconnectivity of distributed brain areas, especially the mPFC, is a neural mechanism for memory function in the absence of one MTL.
The structural brain network topology of episodic memory
This work applied graph theory methods to diffusion-based anatomical networks in order to examine the structural architecture of the medial temporal lobe needed to support effective episodic memory functioning and examined the relationship between performance on tests of verbal and non-verbal episodicMemory with node strength, which indexes how well connected a brain region is in the network.
The influence of age and mild cognitive impairment on associative memory performance and underlying brain networks
Functional connectivity analysis revealed a stronger link of hippocampal and striatal components in older adults in comparison to young controls, regardless of memory impairment, while increased functional connectivity between the hippocampus and the striatum may suggest dedifferentiation, especially in elderly controls.
The focus of this discussion is on episodic memory, but the other forms of memory will be briefly reviewed since the clinical evaluation (and experimental probing) of a specific memory ability usually requires the interpretation of function in these other domains.
Preservation of episodic memory in semantic dementia: The importance of regions beyond the medial temporal lobes
Episodic memory and executive functions in cognitively healthy individuals display distinct neuroanatomical correlates which are differentially modulated by aging
The data extend the critical role of the DMN and ECN by showing that variability in their morphological properties, and not only their activation patterns, affects EM and EFs, respectively and the finding that aging reverts these associations supports previously advanced theories of cognitive neurodevelopment.
Separate elements of episodic memory subserved by distinct hippocampal–prefrontal connections
Applying a pharmacogenetic deactivation technique to investigate the mnemonic contributions of two direct hippocampal–medial prefrontal cortex (mPFC) pathways reveals a previously unsuspected division of function among CA1 neurons that project directly to the mPFC.
Brain Functional Correlates of Episodic Memory Using an Ecological Free Recall Task
FR seems to be a promising task to investigate ecologically the neural correlates of EM, and the recruitment of the anterior AG might be a marker for an optimal functioning of the recall process.
Recognition memory impairments in temporal lobe epilepsy : the contribution of recollection and metacognition
Evidence is provided that memory impairment in TLE is characterised by disordered recollection and recollective experience, and patients can be consciously aware of deficits in underlying cognitive processes contributing to memory performance.


Episodic memory, amnesia, and the hippocampal–anterior thalamic axis
By utilizing new information from both clinical and experimental studies with animals, the anatomy underlying anterograde amnesia has been reformulated and places critical importance on the efferents from the hippocampus via the fornix to the diencephalon.
Frontal lobes and human memory: insights from functional neuroimaging.
It is predicted that the resolution of questions concerning the functional neuroanatomical subdivisions of the frontal cortex will ultimately depend on a fuller cognitive psychological fractionation of memory control processes, an enterprise that will be guided and tested by experimentation.
Hippocampal involvement in human topographical memory: evidence from functional imaging.
  • E. Maguire
  • Biology, Psychology
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 1997
The right hippocampus is clearly involved in processing spatial layouts over long as well as short time-courses, and participates in both the encoding and the retrieval of topographical memory.
Memory consolidation and the medial temporal lobe: a simple network model.
  • P. Alvarez, L. Squire
  • Biology, Psychology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1994
Evidence that the medial temporal lobe memory system is involved in a process of consolidation is reviewed: memories are initially dependent on this system but gradually become established in other areas of the brain.
High-resolution fMRI of Content-sensitive Subsequent Memory Responses in Human Medial Temporal Lobe
The present data suggest a gradient of content sensitivity from posterior (parahippocampal) to anterior (perirhinal) MTL cortex, with MTL cortical regions differentially contributing to successful encoding based on event content.
Neurocognitive aging: prior memories hinder new hippocampal encoding
Recognition memory: What are the roles of the perirhinal cortex and hippocampus?
This work focuses on the central issue in this dispute — the relative contributions of the hippocampus and the perirhinal cortex to recognition memory.
Brain structural and functional abnormalities in mood disorders: implications for neurocircuitry models of depression
Because the MPFC and related limbic structures provide forebrain modulation over visceral control structures in the hypothalamus and brainstem, their dysfunction can account for the disturbances in autonomic regulation and neuroendocrine responses that are associated with mood disorders.
The Neurophysiology of Memory
Cross‐species comparisons show that the patterns of mnemonic activity observed throughout the medial temporal lobe are largely conserved across species and show that neurons in each of the medialporal lobe areas can perform both similar as well as distinctive mnemon functions.