Loss of recent memory after bilateral hippocampal lesions

LOSS OF RECENT MEMORY AFTER BILATERAL HIPPOCAMPAL LESIONS. Bilateral destruction of the hippocampus (cornu ammonis) in a case of dementia. J Neurol Neurosurg Psychiatry.

Loss of recent memory after bilateral hippocampal lesions. The degree of memory loss appears to depend on the extent of hippocampal removal. Removal of only the uncus and amygdala bilaterally does not appear to cause memory impairment.

Bilateral medial temporal lobe resection in man in a persistent impairment of recent memory whenever the removal is carried far enough posteriorly to damage portions of the anterior hippocampus and hippocampal gyrus. Loss of Recent Memory After Bilateral Hippocampal Lesions. William Beecher Scoville. Annals of the New York Academy of Sciences, Vol.

To explain this memory loss , Milner and Penfield had speculated that in each case there had been a pre-existing unsuspected lesion in the hippocampal region of the opposite hemisphere, so that the operation effectively deprived the patients of hippocampal function bilaterally. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (M), or click on a page image below to browse page by page. Bilateral lesions of CAand CAfields of the hippocampus are sufficient to cause a severe amnesic syndrome in humans. National Hospital for Neurology and Neurosurgery, London, UK.

This article has been cited by other articles in PMC. The memory loss in these cases of medial temporal lobe excision involved both anterograde and some retrograde amnesia, but left early memories and technical skills intact. The memory defect appeared immediately after this second operation and has been relatively constant during the past three years, although there was some improvement in the first year after operation. His loss of recent memory is less severe than in the other three cases, and it is possible that the hippocampal -zone destruction on the right (nonoperative) side is only partial.

In this fashion, the prepyriform gyrus, uncus, amygdala, hippocampus, and hippocampal gyrus were resected bilaterally. Recent studies using functional brain imaging in humans and neuropsychological analyses of humans and animals with hippocampal damage have revealed some of the elemental cognitive processes mediated by the hippocampus. In addition, recent characterizations of neuronal firing patterns in behaving animals and humans have suggested how neural representations in the hippocampus underlie those elemental cognitive processes in the service of declarative memory. Scoville’s psychotic patients who had undergone similar treatments, showed that the degree of memory loss was dependent on the extent of damage to the hippocampus.

American man who had a bilateral medial temporal lobectomy to surgically resect the anterior two thirds of his hippocampi, parahippocampal cortices, entorhinal cortices, piriform cortices, and amygdalae in an attempt to cure his epilepsy. Our findings suggest that long-term LA intervention can effectively delay or prevent the decline of learning and memory associated with aging via altered synaptic plasticity. The ablations extended posteriorly along the medial surfaces for a distance of about cm.

The effect of the surgery on his memory was dramatic and immediately evident. RB, along with data on three other patients who had suffered bilateral damage to the hippocampal formation. Essentially there were two types of data: neuropsychological evidence concerning the. The severity of the episodic memory deficit varies as a function of the degree of hippocampal damage. Lacunar amnesia is the loss of memory about one specific event.

It is a type of amnesia that leaves a lacuna (a gap) in the record of memory in the cortex region of the brain. The cause of this type of amnesia is the result of brain damage to the limbic system which control our memories and emotions. Bilateral loss of CApyramidal cells was observe but more CApyramidal cells were spared in WH than in RB, G or LM. To test these ideas, we investigated remote spatial memory in K. In his spatial knowledge, general aspects were preserve but details were lost, a pattern that resembled his memory loss in other domains.

Despite these changes, neuronal responses are resilient to a lack of exposure to a previously completed task or to hippocampus lesions. SOME ADDITIONAL QUANTITATIVE OBSERVATIONS OF IMMEDIATE MEMORY IN A PATIENT 2One-hundred seconds later, H. Figure 1D shows the gradient. Magnetic resonance imaging showed the lesion to be limited to the hippocampal formation bilaterally. Although glioblastoma extends frequently into fiber pathways and expands into the opposite cerebral hemisphere, making a “butterfly” lesion, it is unusual for it to invade the limbic system selectively to this extent.

Retrograde amnesia is inability to recall memories before onset of amnesia. One may be able to encode new memories after the incident. Retrograde is usually caused by head trauma or brain damage to parts of the brain besides the hippocampus. The hippocampus is responsible for encoding new memory.

Her recent work has focused on how cells in the hippocampus signal both the initial formation as well the long-term representation of associative memory.