The Hippocampus: A "Working Memory" Structure? The Effect Of Hippocampal Sclerosis On Working Memory
Cowey CM, Green S
Memory 1996 Jan;4(1):19-30
Univ of London, Dept of Psychology, London, UK
PMID# 8821083; UI# 96418298
Patients with medically intractable Epilepsy and either Hippocampal Sclerosis or Frontal Lobe lesions were compared with healthy controls.
To investigate a possible NeuroAnatomical correlate of a component of Working Memory: The Central Executive.
Patients were tested on a Short-Term Memory Task which comprised Visuo-Spatial and Verbal Components, in single and concurrent trials.
Differences were found between the patient groups for Dual-Task Capacity, despite being equated on single-task trials. Patients with Frontal Lobe damage were the most affected by the demands of Attention division.
The results of this study do not support the thesis of a Hippocampal role in the Working Memory component examined, but point to a Frontal Lobe focus for this Janusian Cognitive Function.
An unexpected finding of an increment in performance over the trials of Visuo-Spatial Assessment, in patients with Hippocampal Sclerosis, is presented.
Working Memory Impairment Among Persons With Chronic/Progressive Multiple Sclerosis
Grigsby J, Ayarbe SD, Kravcisin N, Busenbark D
J Neurol 1994 Jan;241(3):125-31
Univ of Colorado Health Sciences Center, Center for Health Services Research, Denver, Colorado 80222
PMID# 8164013; UI# 94216908
We examined Short-Term Memory (STM) among a group of 23 definite, Chronic/Progressive Multiple Sclerosis (MS) patients.
All of whom had experienced recent significant disease activity, and a control group matched closely on age and education. MS patients were impaired, relative to controls, on the majority of the measures used.
Although there were no significant differences between groups on the Mini Mental State Examination, patients performed more poorly on digits forward and backward, the Brown-Peterson test, and the Logical Memory Scale of the Revised Wechsler Memory Scale (both immediate and delayed).
Performance on tests sensitive to Central Processing Capacity was significantly correlated with measures of STM. Working Memory was significantly impaired in this sample of Chronic/Progressive MS patients.
In conjunction with previous research showing Deficient Information Processing and PreFrontal Dysfunction among this population.
The findings suggest that an Impairment Of Central Information Processing may be a fundamental aspect of the Mnestic and Cognitive Decline observed in many Chronic/Progressive MS patients.
Working Memory Deficits In Multiple Sclerosis: A Controlled Study With Auditory P600 Correlates
Sfagos C, Papageorgiou CC, Kosma KK, Kodopadelis E, Uzunoglu NK, Vassilopoulos D, Rabavilas AD
J Neurol NeuroSurg Psychiatry 2003 Sep;74(9):1231-1235
University of Athens, Department of Neurology, Eginition Hospital, Athens, Greece; University of Athens, Department of Psychiatry, Eginition Hospital; National Technical University of Athens, Department of Electrical and Computer Engineering; and University Mental Health Research Institute, Athens
Recently, the P600 component of Event Related Potentials, a waveform that is conceived to be generated and/or modulated by Basal Ganglia and Cingulate Area has been considered an index of the completion of any synchronized operation after target detection, having much in common with Working Memory operation.
Moreover, dysfunction of these Brain structures as well as Working Memory deficits have been implicated in the pathophysiology of Multiple Sclerosis.
The aim of this study was to investigate the patterns of P600 elicited during a Working Memory test in Multiple Sclerosis patients compared with healthy controls.
Twenty two definite, Chronic/Progressive Multiple Sclerosis patients, with recent exacerbation of their illness, and 20 normal subjects matched for age, sex, and educational level, were studied with a computerized version of the digit span test of Wechsler batteries.
Auditory P600 were measured during the anticipatory period of this test.
The patient group, as compared with healthy controls, showed significantly reduced latencies of P600 at Left Frontal Areas and reduced P600 amplitudes at Left TemporoParietal Region.
Moreover, Memory performance of patients was significantly more impaired when compared with healthy controls.
These findings may indicate that Multiple Sclerosis is associated with abnormal features of the completion of synchronized operation after target detection, as they are reflected by P600 amplitudes and latencies.
Dysfunction of this mechanism may contribute to the identification of basic Cognitive processes that could account for the Cognitive Deficits in Multiple Sclerosis.
Cognition In The Early Stage Of Multiple Sclerosis
Schulz D, Kopp B, Kunkel A, Faiss JH
J Neurol 2006 Aug;253(8):1002-10
Landesklinik Teupitz, Department of Neurology, Buchholzer Str. 21, 15755 Teupitz, Germany
Cognitive Dysfunctions may contribute to limitation of everyday activities of patients with Multiple Sclerosis (MS).
Recent studies have demonstrated that 45 to 65% of MS-patients are Cognitively Impaired.
The profile of MS-related Cognitive Dysfunctions varies greatly. It includes Memory and Learning deficits, Attention deficits, Executive dysfunctions and Visuo-Spatial deficits.
Most studies of Cognition in MS examined patients in later stages, often including MS-patients with marked physical disabilities.
Studies of Cognitive Dysfunctions in the early stage of the disease are rare.
This study specifically aimed at evaluating and characterizing Cognitive Impairments in the early stage of MS, and determining specific patterns of Cognitive Dysfunction.
21 MS patients, experiencing their first Neurological symptoms not more than two years previously, and 22 healthy controls were compared.
A comprehensive NeuroPsychological test-battery was used to evaluate MS-related Cognition.
The battery consisted of Memory and Learning tests, Executive functioning tests and a Visuo Spatial functioning test.
A computerized Attention test-battery was also included, which assess accuracy and speed of test responses. In addition Depression and intellectual capabilities were assessed.
Compared with healthy controls, MS-patients in the early stage of the disease performed significantly lower on each NeuroPsychological assessment, except for Verbal Short-Term Memory.
In particular, MS-patients showed a lengthened reaction time for Simple and Focused Attention (19-38%), impaired Non-Verbal Memory function (RVDLT recognition: 33%) and a Planning deficit (24%).
Associations between Information Processing Speed and disease course and the employment situation were additionally found.
However, patients did not have clinically relevant Depression rates on the ADS-L and Visuo Spatial abilities remain preserved.
Our findings revealed discrete Cognitive Dysfunction in MS-patients within the early stage of the disease.