scholarly journals Against memory systems

2002 ◽  
Vol 357 (1424) ◽  
pp. 1111-1121 ◽  
Author(s):  
David Gaffan
Keyword(s):  
Temporal Lobe ◽  
Cortical Neurons ◽  
Medial Temporal Lobe ◽  
Temporal Cortex ◽  
Memory Systems ◽  
Memory System ◽  
Memory Processing ◽  
Multiple Memory Systems ◽  
Cortical Areas ◽  
Severe Impairment

The medial temporal lobe is indispensable for normal memory processing in both human and non–human primates, as is shown by the fact that large lesions in it produce a severe impairment in the acquisition of new memories. The widely accepted inference from this observation is that the medial temporal cortex, including the hippocampal, entorhinal and perirhinal cortex, contains a memory system or multiple memory systems, which are specialized for the acquisition and storage of memories. Nevertheless, there are some strong arguments against this idea: medial temporal lesions produce amnesia by disconnecting the entire temporal cortex from neuromodulatory afferents arising in the brainstem and basal forebrain, not by removing cortex; the temporal cortex is essential for perception as well as for memory; and response properties of temporal cortical neurons make it impossible that some kinds of memory trace could be stored in the temporal lobe. All cortex is plastic, and it is possible that the same rules of plasticity apply to all cortical areas; therefore, memory traces are stored in widespread cortical areas rather than in a specialized memory system restricted to the temporal lobe. Among these areas, the prefrontal cortex has an important role in learning and memory, but is best understood as an area with no specialization of function.

scholarly journals Distinct Cortical Anatomy Linked to Subregions of the Medial Temporal Lobe Revealed by Intrinsic Functional Connectivity

2008 ◽  
Vol 100 (1) ◽  
pp. 129-139 ◽  
Author(s):  
Itamar Kahn ◽  
Jessica R. Andrews-Hanna ◽  
Justin L. Vincent ◽  
Abraham Z. Snyder ◽  
Randy L. Buckner
Keyword(s):  
Functional Connectivity ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Temporal Cortex ◽  
Memory System ◽  
Retrosplenial Cortex ◽  
The Body ◽  
Parallel Pathways ◽  
Ventral Medial Prefrontal Cortex ◽  
Adjacent Structures

The hippocampus and adjacent cortical structures in the medial temporal lobe (MTL) contribute to memory through interactions with distributed brain areas. Studies of monkey and rodent anatomy suggest that parallel pathways converge on distinct subregions of the MTL. To explore the cortical areas linked to subregions of the MTL in humans, we examined cortico-cortical and hippocampal-cortical correlations using high-resolution, functional connectivity analysis in 100 individuals. MTL seed regions extended along the anterior to posterior axis and included hippocampus and adjacent structures. Results revealed two separate brain pathways that correlated with distinct subregions within the MTL. The body of the hippocampus and posterior parahippocampal cortex correlated with lateral parietal cortex, regions along the posterior midline including posterior cingulate and retrosplenial cortex, and ventral medial prefrontal cortex. By contrast, anterior hippocampus and the perirhinal/entorhinal cortices correlated with distinct regions in the lateral temporal cortex extending into the temporal pole. The present results are largely consistent with known connectivity in the monkey and provide a novel task-independent dissociation of the parallel pathways supporting the MTL memory system in humans. The cortical pathways include regions that have undergone considerable areal expansion in humans, providing insight into how the MTL memory system has evolved to support a diverse array of cognitive domains.

Remembering

Daedalus ◽  
2015 ◽  
Vol 144 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Larry R. Squire ◽  
John T. Wixted
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Human Memory ◽  
Memory Systems ◽  
Consolidation Process ◽  
Multiple Memory Systems ◽  
Memory Work ◽  
Major Development ◽  
The Brain

A major development in understanding the structure and organization of memory was the identification of the medial temporal lobe memory system as one of the brain systems that support memory. Work on this topic began in the 1950s with the study of the noted amnesic patient H.M. and culminated in studies of an animal model of human memory impairment in the nonhuman primate. These discoveries opened new frontiers of research concerned with the functional specialization of structures within the medial temporal lobe, the existence of multiple memory systems, the process of memory consolidation, and the role of neural replay and sleep in the consolidation process. This work also led to new insights about how and where memories are ultimately stored in the brain. All of this research has improved our understanding of how memory is affected by normal aging and why it is so profoundly impaired by the pathological processes associated with dementia.

scholarly journals Revisiting the Role of the Medial Temporal Lobe in Motor Learning

2021 ◽  
pp. 1-18
Author(s):  
Samuel D. McDougle ◽  
Sarah A. Wilterson ◽  
Nicholas B. Turk-Browne ◽  
Jordan A. Taylor
Keyword(s):  
Motor Learning ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Declarative Memory ◽  
Action Selection ◽  
Memory Systems ◽  
Memory Processes ◽  
Multiple Memory Systems ◽  
Selection Strategies ◽  
Arbitrary Action

Abstract Classic taxonomies of memory distinguish explicit and implicit memory systems, placing motor skills squarely in the latter branch. This assertion is in part a consequence of foundational discoveries showing significant motor learning in amnesics. Those findings suggest that declarative memory processes in the medial temporal lobe (MTL) do not contribute to motor learning. Here, we revisit this issue, testing an individual (L. S. J.) with severe MTL damage on four motor learning tasks and comparing her performance to age-matched controls. Consistent with previous findings in amnesics, we observed that L. S. J. could improve motor performance despite having significantly impaired declarative memory. However, she tended to perform poorly relative to age-matched controls, with deficits apparently related to flexible action selection. Further supporting an action selection deficit, L. S. J. fully failed to learn a task that required the acquisition of arbitrary action–outcome associations. We thus propose a modest revision to the classic taxonomic model: Although MTL-dependent memory processes are not necessary for some motor learning to occur, they play a significant role in the acquisition, implementation, and retrieval of action selection strategies. These findings have implications for our understanding of the neural correlates of motor learning, the psychological mechanisms of skill, and the theory of multiple memory systems.

Individual Sequence Representations in the Medial Temporal Lobe

2013 ◽  
Vol 25 (7) ◽  
pp. 1111-1121 ◽  
Author(s):  
Kristjan Kalm ◽  
Matthew H. Davis ◽  
Dennis Norris
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Memory Systems ◽  
Long Term Memory ◽  
Specific Sequence ◽  
Level Of Activity ◽  
Serial Recall Task ◽  
Letter Names ◽  
Multivariate Pattern

Much of what we need to remember consists of sequences of stimuli, experiences, or events. Repeated presentation of a specific sequence establishes a more stable long-term memory, as shown by increased recall accuracy over successive trials of an STM task. Here we used fMRI to study the neural mechanisms that underlie sequence learning in the auditory–verbal domain. Specifically, we track the emergence of neural representations of sequences over the course of learning using multivariate pattern analysis. For this purpose, we use a serial recall task, in which participants have to recall overlapping sequences of letter names, with some of those sequences being repeated and hence learned over the course of the experiment. We show that voxels in the hippocampus come to encode the identity of specific repeated sequences although the letter names were common to all sequences in the experiment. These changes could have not been caused by changes in overall level of activity or to fMRI signal-to-noise ratios. Hence, the present results go beyond conventional univariate fMRI methods in showing a critical contribution of medial-temporal lobe memory systems to establishing long-term representations of verbal sequences.

Simultaneous Electroencephalographic and Electocorticographic Recordings of Lateralized Periodic Discharges in Temporal Lobe Epilepsy

2020 ◽  
pp. 155005942097226
Author(s):  
Ayumi Sakata ◽  
Nobutaka Mukae ◽  
Takato Morioka ◽  
Shunya Tanaka ◽  
Takafumi Shimogawa ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Chronic Conditions ◽  
Medial Temporal Lobe ◽  
Temporal Cortex ◽  
Temporal Region ◽  
Pathophysiological Mechanism ◽  
Periodic Discharges ◽  
Pathological Conditions ◽  
Eeg Pattern

Objective Lateralized periodic discharges (LPDs), which constitute an abnormal electroencephalographic (EEG) pattern, are most often observed in critically ill patients with acute pathological conditions, and are less frequently observed in chronic conditions such as focal epilepsies, including temporal lobe epilepsy (TLE). Here we aim to explore the pathophysiological mechanism of LPD in TLE. Methods We retrospectively selected 3 patients with drug-resistant TLE who simultaneously underwent EEG and electrocorticography (ECoG) and demonstrated LPDs. We analyzed the correlation between the EEG and ECoG findings. Results In patients 1 and 2, LPDs were recorded in the temporal region of the scalp during the interictal periods, when repeated spikes followed by slow waves (spike-and-wave complexes; SWs) and periodic discharges (PDs) with amplitudes of >600 to 800 µV appeared in the lateral temporal lobe over a cortical area of >10 cm2. In patient 3, when the ictal discharges persisted and were confined to the medial temporal lobe, repeated SWs were provoked on the lateral temporal lobe. When repeated SWs with amplitudes of >800 µV appeared in an area of the lateral temporal lobe of >10 cm2, the corresponding EEG discharges appeared on the temporal scalp. Conclusions LPDs in patients with TLE originate from repeated SWs and PDs of the lateral temporal lobe, which might represent a highly irritable state of the lateral temporal cortex during both interictal and ictal periods.

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