By utilizing new information from both clinical and experimental (lesion, electrophysiological, and gene-activation) studies with animals, the anatomy underlying anterograde amnesia has been reformulated. The distinction between temporal lobe and diencephalic amnesia is of limited value in that a common feature of anterograde amnesia is damage to part of an “extended hippocampal system” comprising the hippocampus, the fornix, the mamillary bodies, and the anterior thalamic nuclei. This view, which can be traced back to Delay and Brion (1969), differs from other recent models in placing critical importance on the efferents from the hippocampus via the fornix to the diencephalon. These are necessary for the encoding and, hence, the effective subsequent recall of episodic memory. An additional feature of this hippocampal–anterior thalamic axis is the presence of projections back from the diencephalon to the temporal cortex and hippocampus that also support episodic memory. In contrast, this hippocampal system is not required for tests of item recognition that primarily tax familiarity judgements. Familiarity judgements reflect an independent process that depends on a distinct system involving the perirhinal cortex of the temporal lobe and the medial dorsal nucleus of the thalamus. In the large majority of amnesic cases both the hippocampal–anterior thalamic and the perirhinal–medial dorsal thalamic systems are compromised, leading to severe deficits in both recall and recognition.

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Episodic memory, amnesia, and the hippocampal–anterior thalamic axis.

Summary Multiple sclerosis (MS) is a progressive disease of the CNS that is characterised by widespread lesions in the brain and spinal cord. MS results in motor, cognitive, and neuropsychiatric symptoms, all of which can occur independently of one another. The common cognitive symptoms include deficits in complex attention, efficiency of information processing, executive functioning, processing speed, and long-term memory. These deficits detrimentally affect many aspects of daily life, such as the ability to run a household, participate fully in society, and maintain employment—factors that can all affect the overall quality of life of the patient. The increased use of neuroimaging techniques in patients with MS has advanced our understanding of structural and functional changes in the brain that are characteristic of this disease, although much remains to be learned. Moreover, examination of efforts to treat the cognitive deficits in MS is still in the early stages.

https://www.thelancet.com/pdfs/journals/laneur/PIIS1474-4422(08)70259-X.pdf

Cognitive impairment in multiple sclerosis

Research over the past two decades broadly supports the claim that mindfulness meditation - practiced widely for the reduction of stress and promotion of health - exerts beneficial effects on physical and mental health, and cognitive performance. Recent neuroimaging studies have begun to uncover the brain areas and networks that mediate these positive effects. However, the underlying neural mechanisms remain unclear, and it is apparent that more methodologically rigorous studies are required if we are to gain a full understanding of the neuronal and molecular bases of the changes in the brain that accompany mindfulness meditation.

The neuroscience of mindfulness meditation

http://jtoomim.org/brain-training/Zeidan2010_Mindfulness_Meditation.pdf

Mindfulness meditation improves cognition: Evidence of brief mental training☆

Working memory (WM) is a cognitive system that strongly relates to a person’s ability to reason with novel information and direct attention to goal-relevant information. Due to the central role that WM plays in general cognition, it has become the focus of a rapidly growing training literature that seeks to affect broad cognitive change through prolonged training on WM tasks. Recent work has suggested that the effects of WM training extend to general fluid intelligence, attentional control, and reductions in symptoms of ADHD. We present a theoretically motivated perspective of WM and subsequently review the WM training literature in light of several concerns. These include (a) the tendency for researchers to define change to abilities using single tasks, (b) inconsistent use of valid WM tasks, (c) no-contact control groups, and (d) subjective measurement of change. The literature review highlights several findings that warrant further research but ultimately concludes that there is a need to directly demonstrate that WM capacity increases in response to training. Specifically, we argue that transfer of training to WM must be demonstrated using a wider variety of tasks, thus eliminating the possibility that results can be explained by task specific learning. Additionally, we express concern that many of the most promising results (e.g., increased intelligence) cannot be readily attributed to changes in WM capacity. Thus, a critical goal for future research is to uncover the mechanisms that lead to transfer of training.

https://analyseeconomique.files.wordpress.com/2012/10/is-working-memory-training-effective.pdf

Is working memory training effective

https://www.archives-pmr.org/article/S0003-9993(00)90052-2/pdf

Ginkgo biloba extract: mechanisms and clinical indications.

OBJECTIVES—To examine patterns of brain activation while performing a working memory task in persons with moderate to severe traumatic brain injury (TBI) and healthy controls. It is well established that working memory is an area of cognition that is especially vulnerable to disruption after TBI. Although much has been learned about the system of cerebral representation of working memory in healthy people, little is known about how this system is disrupted by TBI.
METHODS—Functional magnetic resonance imaging (fMRI) was used to assess brain activation during a working memory task (a modified version of the paced auditory serial addition test) in nine patients with TBI and seven healthy controls.
RESULTS—Patients with TBI were able to perform the task, but made significantly more errors than healthy controls. Cerebral activation in both groups was found in similar regions of the frontal, parietal, and temporal lobes, and resembled patterns of activation found in previous neuroimaging studies of working memory in healthy persons. However, compared with the healthy controls, the TBI group displayed a pattern of cerebral activation that was more regionally dispersed and more lateralised to the right hemisphere. Differences in lateralisation were particularly evident in the frontal lobes.
CONCLUSIONS—Impairment of working memory in TBI seems to be associated with alterations in functional cerebral activity.

https://jnnp.bmj.com/content/jnnp/71/2/161.full.pdf

Functional magnetic resonance imaging of working memory impairment after traumatic brain injury

Speed of information processing was assessed in patients with multiple sclerosis and healthy controls using both an auditory and visual task designed to control for accuracy of performance across groups. After controlling for accuracy of performance, patients with multiple sclerosis were found to have significantly slower speed of information processing relative healthy controls, irrespective of the modality of stimulus presentation (auditory or visual). When given an adequate amount of time to process information, however, the patients performed similarly to controls. These results suggest that persons with multiple sclerosis experience deficits specifically in processing speed but not performance accuracy. Results are discussed in terms of rehabilitative guidelines for the cognitive improvement of persons with multiple sclerosis.

https://jnnp.bmj.com/content/jnnp/67/5/661.full.pdf

Speed of information processing as a key deficit in multiple sclerosis: implications for rehabilitation

This study examined whether verbal and visual memory impairments in multiple sclerosis (MS) are attributable to deficits in acquisition, storage, or retrieval. Volunteers with MS (n = 40) and healthy controls (n = 20) rehearsed a word list and a checkerboard pattern using a selective reminding procedure until two consecutive error-free trials were attained. Recall and recognition were assessed after 30 min and 90 min (and 1 week for verbal material) delays. The MS group required significantly more trials to attain criterion on both learning tests. Once equated for acquisition, both groups performed similarly on verbal recall and recognition. However the MS group performed significantly worse on measures of visual recall and recognition. The results suggest that the verbal memory impairment in MS is due to deficient acquisition, while the visual memory impairment in MS is attributable to deficits in acquisition and storage.

Bruce J. Diamond

Papers

Mindfulness meditation improves cognition: Evidence of brief mental training☆

Ginkgo biloba extract: mechanisms and clinical indications.

Functional magnetic resonance imaging of working memory impairment after traumatic brain injury

Speed of information processing as a key deficit in multiple sclerosis: implications for rehabilitation

Acquisition and storage deficits in multiple sclerosis.