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PubMed2002

The effects of pretraining and reminder treatments on retrograde amnesia in rats: comparison of lesions to the fornix or perirhinal and entorhinal cortices.

The present experiment examined the effects of pretraining and reminder treatments on the retention of a nonrelational odor-guided digging task following lesions to the hippocampal formation (i.e., fornix) or parahippocampal region (i.e., perirhinal and entorhinal cortices). The results showed that fornix-lesioned rats and control rats had good retention of the task and did not differ from each other; however, perirhinal- and entorhinal-lesioned rats were severely impaired and differed from fornix and control rats. The present experiment found no attenuation of amnesia following pretraining, which may be due to the lesion technique employed and the size of the resulting lesions. However, the experiment found a significant difference in performance following a reminder treatment, even in the severely impaired perirhinal- and entorhinal-lesioned group.

Amnesia, Retrograde↗
PubMed1979

Recurrent transient global amnesia in a case with cerebrovascular lesions and livedo reticularis (Sneddon Syndrome).

Eight attacks of transient global amnesia were observed in a female patient who suffered from livedo reticularis and a series of other neurological symptoms, which were transient in most stances. The neurological deficits include focal epileptic attacks, unilateral loss of vision, paresis of left arm and/or leg and dysarthria. The first amnestic attack was seen at the age of 19. The episodes lasted from a few to 3 days. The intervals between the amnestic episodes varied between a few days and 11 years. The livedo reticularis became more obvious during each neurological episode and was less pronounced during the time of remission. A benign type of essential hypertension and parproteinemia (gamma-M) was found. The investigations failed to show any evidence of essential thrombocythemia, polyarteriitis nodosa, lupus erythematodes and other immune complex diseases. The underlaying disease remained unclear.

Amnesia↗
PubMed1989

Amnesia due to bilateral hippocampal glioblastoma. MRI finding.

The authors report a unique case of glioblastoma which caused permanent amnesia. 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.

Amnesia↗
PubMed1983

Amnesia induced by stimulation of the amygdala is attenuated by hexamethonium.

Bilateral subseizure stimulation of the amygdala given immediately following training in an inhibitory avoidance task produced retrograde amnesia. Hexamethonium (3.0 and 10.0 mg/kg), a peripherally acting nicotinic cholinergic antagonist, attenuated the retention deficits induced by amygdala stimulation if the drug was given 30 min prior to, but not immediately following training. Hexamethonium had no effect in normal unoperated animals, but did produce a retention deficit in operated control (nonstimulated) animals if it was given immediately following training (3.0 and 10.0 mg/kg). The results suggest that memory deficits induced by electrical stimulation of the amygdala are associated with, or perhaps mediated in some way by peripheral autonomic function.

Amnesia↗
PubMed1984

The nature of lorazepam-induced amnesia.

The effect of lorazepam (2.5 mg) was assessed in two tests of short-term retention (digit-span and Benton Visual Retention), and in verbal learning and picture recognition tests. Lorazepam was without effect in a test of digit-span, but it impaired performance in the Benton Visual Retention and picture recognition tests. In the verbal learning test lorazepam caused a severe anterograde amnesia. Increasing arousal during the presentation of material partially overcame this effect, but also improved the performance of controls. Lorazepam-treated subjects were able to learn a backwards-reading task at a rate no different from controls. The deficits caused by lorazepam are similar to those that have been observed in patients with the amnesic syndrome.

Adult↗
PubMed1997

Semantic amnesia without dementia: documentation of a case.

We described the case of a patient affected by a progressive semantic memory disorder associated with prevalent temporal lobe atrophy. This deficit seems to be "pure" in the sense that it has not been found to overlap with other cognitive deficits (intellectual, linguistic, perceptual, visuo-spatial etc.) for a long time. Furthermore, despite his impaired semantic knowledge, the autobiographical memory of the patient was largely intact. This case therefore represents a form of "semantic amnesia" without dementia, and supports the hypothesis that there is a partial distinction between "semantic" and "episodic" memory.

Amnesia↗
PubMed1989

Ethmoidal meningioma revealed by transient global amnesia.

A patient in whom transient global amnesia (TGA) led to the diagnosis of an ethmoidal meningioma is described. One year after neurosurgery, the patient showed an impairment of long-term memory, without any clinical or neuroradiological sign of relapse. We suggest that TGA may express a preexisting subclinical impairment of memory neuronal systems.

Amnesia↗
PubMed1987

Transient global amnesia: an analysis of 19 cases.

19 patients with episodes of transient global amnesia (TGA) were studied, with special reference to the laboratory and instrumental findings (mainly EEG and CT scan). A high proportion of subjects had several risk factors for cerebrovascular disease or CT abnormalities.

Adult↗
PubMedDate not supplied

Molecular basis of the activity of the dopamine synapse in the mechanisms of learning and amnesia.

The neurochemical correlates of dopamine synapse activity were studied during the retrieval of memory traces and in the absence of retrieval ("psychogenic" amnesia). The physiochemical parameters of D2 receptor function, the synaptic membrane, and the catechol content were assessed in various regions of the brain (striatum, neostriatum, hypothalamus, amygdala, frontal cortex, hippocampus, nucleus accumbens, and nuclei A9 and A10) in intact, trained, and amnesiac rats. It was demonstrated that disturbances in memory trace retrieval were associated with decreased activation of synaptic dopamine receptors and alterations in the dopamine transformation pathway in the rat brain.

Amnesia↗
PubMedDate not supplied

Transient global amnesia after sexual intercourse.

BACKGROUND: Transient global amnesia presents as paroxysmal, transient loss of memory function and has been shown to have a number of inciting factors. AIMS: To report a case and its inciting factor in order to heighten awareness of the condition. METHODS: A 56-year-old woman who presented with TGA after sexual intercourse is reported. RESULTS: The episode of TGA resolved after 14 hours. Results of laboratory tests including MRI brain and MR angiogram and venogram were normal. CONCLUSION: An inciting event can often be identified for TGA and a targeted history should be used to help elicit such events.

Amnesia, Transient Global↗
PubMed1999

Ganglioside GM1 attenuates scopolamine-induced amnesia in rats and mice.

Some experimental evidence suggests that the beneficial effects of monosialoganglioside GM1 on learning and memory could be related to an improving effect in central cholinergic function. The present study investigates the effects of GM1 on the memory impairment induced by scopolamine in rats or mice tested in passive (PA) and discriminative avoidance (DA) tasks, respectively. Wistar EPM-1 male rats and Swiss EPM-M1 male mice were treated daily IP with 50 mg/kg GM1 or saline for 7 or 14 days, respectively. Twenty-four hours after the last injection, GM1-treated animals received 1 mg/kg scopolamine (GM1-SCO) and saline-treated animals received 1 mg/kg scopolamine (SAL-SCO) or saline (SAL-SAL) IP. Twenty minutes later, the animals were submitted to PA or DA conditioning, and tests were performed 24 h later. The latency in entering the dark chamber of the PA apparatus (LD) presented by SAL-SCO rats was significantly decreased when compared to that presented by SAL-SAL animals. GM1-SCO animals showed an increased LD when compared to SAL-SCO animals and were not significantly different from SAL-SAL rats. GM1-SCO and SAL-SAL (but not SAL-SCO) mice spent significantly less time in the aversive enclosed arm of the discriminative avoidance apparatus when compared to the time spent in the non-aversive enclosed arm. The results are consistent with the interpretation that GM1 attenuates scopolamine-induced amnesia. Although not eliminating the participation of other transmitter systems, the present study indicates a possible role of central cholinergic transmission in the action of this compound on learning and memory.

Amnesia↗
PubMed2002

Transient global amnesia: increased signal intensity in the right hippocampus on diffusion-weighted magnetic resonance imaging.

We report on a patient with pure transient global amnesia (TGA) whose magnetic resonance imaging (MRI) demonstrated a small region of increased signal intensity in the right hippocampus on diffusion-weighted imaging (DWI). DWI was sensitive and useful for evaluating the early stage of TGA and might help to explain the pathophysiology of TGA.

Amnesia, Transient Global↗
PubMed2004

Cerebral blood flow SPET in transient global amnesia with automated ROI analysis by 3DSRT.

The aim of this study was to determine the areas involved in episodes of transient global amnesia (TGA) by calculation of cerebral blood flow (CBF) using 3DSRT, fully automated ROI analysis software which we recently developed. Technetium-99m L, L-ethyl cysteinate dimer single-photon emission tomography ((99m)Tc-ECD SPET) was performed during and after TGA attacks on eight patients (four men and four women; mean study interval, 34 days). The SPET images were anatomically standardized using SPM99 followed by quantification of 318 constant ROIs, grouped into 12 segments (callosomarginal, precentral, central, parietal, angular, temporal, posterior cerebral, pericallosal, lenticular nucleus, thalamus, hippocampus and cerebellum), in each hemisphere to calculate segmental CBF (sCBF) as the area-weighted mean value for each of the respective 12 segments based on the regional CBF in each ROI. Correlation of the intra- and post-episodic sCBF of each of the 12 segments of the eight patients was estimated by scatter-plot graphical analysis and Pearson's correlation test with Fisher's Z-transformation. For the control, (99m)Tc-ECD SPET was performed on eight subjects (three men and five women) and repeated within 1 month; the correlation between the first and second sCBF values of each of the 12 segments was evaluated in the same way as for patients with TGA. Excellent reproducibility between the two sCBF values was found in all 12 segments of the control subjects. However, a significant correlation between intra- and post-episodic sCBF was not shown in the thalamus or angular segments of TGA patients. The present study was preliminary, but at least suggested that thalamus and angular regions are closely involved in the symptoms of TGA.

Adult↗
PubMed2002

Transient Global Amnesia. Evidence against vascular ischemic etiology from diffusion weighted imaging.

The etiology of Transient Global Amnesia (TGA) is still obscure. Diffusion-Weighted-Imaging (DWI) provides conflicting evidence concerning a possible vascular ischemic cause in mesiotemporal structures including the hippocampal region. The question remains open whether conflicting observations resulted from different observation times. DWI was performed at a time interval with known sensitivity for detection of ischemia. Ten patients (5 male, 5 female; mean age of 63 +/- 9, range 41-71 years) with typical TGA were investigated at an average delay of 18 hours (range 6 to 44 hours) between onset of symptoms and magnetic resonance imaging (transversal DW-, T1W- and T2W-MRI). Five patients received apparent-diffusion-coefficient (ADC)-mapping. Cerebrovascular studies (ECG, TTE and extra/transcranial dopplersonographic and duplexultrasonic investigation) and EEG were normal in all patients. DW-MRI-sequences and ADC-maps, if performed, were normal in all patients. Conventional T2W-MRI in 3 out of 10 patients showed microangiopathic subcortical changes and lacunar strokes of older origin. We conclude that TGA does not result from a vascular ischemic etiology in the majority of cases.

Adult↗