A partial habituation method to test for anterograde and retrograde amnestic treatment effects: Evidence that antagonism of the NMDA receptor can induce anterograde but not retrograde amnestic effects.

BACKGROUND: A progressive decrease in spontaneous locomotion with repeated exposure to a novel environment has been assessed using both within and between-session measures. While both are well-established and reliable measurements, neither are useful alone as methods to concurrently assess treatment effects on acquisition and retention of habituation. NEW METHOD: We report a behavioral method that measures habituation by combining the within and between measurements of locomotion. We used a 30 min session divided into 6 five min blocks. In the first novel environment session activity was maximal in the first 5 min block but was reduced to a low level by the sixth block, indicative of within-session habituation. Using 8 daily sessions, we showed that this terminal block low level of activity progressed incrementally to the first block to achieve complete habituation. RESULTS/COMPARISON WITH EXISTING METHODS: Within-session activity across sessions was used to identify different stages of between session habituation. It was then possible to assess drug treatment effects from partial to complete habituation, so that treatment effects on retention of the previously acquired partial habituation, expressed as a reversion to an earlier within session habituation pattern (retrograde amnesia assessment), as well as the effects on new learning by the failure in subsequent sessions to acquire complete between-session habituation (anterograde amnesia assessment). CONCLUSIONS: The use of spontaneous motor activity to assess learning and memory effects provides the opportunity to assess direct treatment effects on behavior and motor activity in contrast to many learning and memory models.

Postischemic fish oil treatment restores long-term retrograde memory and dendritic density: An analysis of the time window of efficacy.

We reported that fish oil (FO) prevented the loss of spatial memory caused by transient, global cerebral ischemia (TGCI), provided the treatment covered the first days prior to and after ischemia. Continuing these studies, trained rats were subjected to TGCI, and FO was administered for 10days, with a time window of efficacy (TWE) of 4, 8 or 12h post-ischemia. Retrograde memory was assessed up to 43days after TGCI. In another experiment, ischemic rats received FO with a 4- or 12-h TWE, and dendritic density was assessed in the hippocampus and cerebral cortex. The brain lipid profile was evaluated in sham-operated and ischemic rats that were treated with FO or vehicle with a 4-h TWE. Ischemia-induced retrograde amnesia was prevented by FO administration that was initiated with either a 4- or 8-h TWE. Fish oil was ineffective after a 12-h TWE. Independent of the TWE, FO did not prevent ischemic neuronal death. In the hippocampus, but not cerebral cortex, TGCI-induced dendritic loss was prevented by FO with a 4-h TWE but not 12-h TWE. The level of docosahexaenoic acid almost doubled in the hippocampus in ischemic, FO-treated rats (4-h TWE). The data indicate that (i) the anti-amnesic effect of FO can be observed with a TWE of up to 8h, (ii) the stimulation of dendritic neuroplasticity may have contributed to this effect, and (iii) DHA in FO may be the main active constituent in FO that mediates the cognitive and neuroplasticity effects on TGCI.

Memoria autobiográfica en pacientes con epilepsia del lóbulo temporal por esclerosis hipocampal / Autobiographical memory in patients with temporal lobe epilepsy by hippocampal sclerosis

Introducción: la epilepsia del lóbulo temporal (ELT) suele cursar con trastornos en el funcionamiento mnésico. Es probable que el paciente con epilepsia tenga dificultades en la memoria autobiográfica, principalmente en los casos donde la etiología es la esclerosis hipocampal (EH). Objetivo: determinar las posibles alteraciones de la memoria autobiográfica en los pacientes con epilepsia del lóbulo temporal por esclerosis hipocampal, en comparación con personas sanas. Material y métodos: la muestra estuvo conformada por 25 pacientes con diagnóstico electroclínico e imagenalógico de ELT por EH y fue contrastada con 15 controles sanos. A los pacientes que previamente habían sido valorados por neurología y neuropsicología, se les suministró la Entrevista de Memoria Autobiográfica para valorar el desempeño en memoria personal semántica e incidentes autobiográficos. Para la comparación de los pacientes frente a los controles en memoria autobiográfica, se utilizó la prueba U de Mann Whitney y se calculó el tamaño del efecto no paramétrico. Resultados: los pacientes presentaron dificultades en el recuerdo de la información personal semántica de los últimos cinco años y marcadas alteraciones en el recuerdo de incidentes autobiográficos relacionados con la niñez, la adultez y la vida reciente. Conclusión: los resultados confirman las dificultades que los pacientes con ELT por EH presentan en la activación de rastros de memoria en el hipocampo para la evocación y re-experimentación detallada de los incidentes autobiográficos de toda su historia personal.

Introduction: The temporal lobe epilepsy (TLE) is usually associated with memory disorders. Patients with epilepsy probably will have difficulties in the autobiographical memory, mainly in cases where the etiology is for hippocampal sclerosis (HS) Objective: Determine the possible impairments of autobiographical memory in patients with temporal lobe epilepsy by hippocampal sclerosis compared to healthy subjects. Materials and methods: The sample was composed by 25 patients diagnosed with TLE by HS using neuroimaging, and where contrasted with a control group composed by 15 healthy subjects. Patients who previously were evaluated by neurology and neuropsychology, performed the autobiographical memory interview to test the semantic personal memory performance and autobiographical incidents. In order to compare autobiographical memory in both groups, the U test from Mann Whitney was used and the size of the no parametric effect was calculated. Results: he patients presented difficulties remembering personal semantic information in the last 5 years and had relevant alterations remembering autobiographical incidents related to childhood, adulthood, and recent life. Conclusion: The results confirmed the difficulties of patients with TLE by HS to activate memories from the hippocampus for evoking and experimenting again detailed autobiographical incidents from their personal history.

Memoria autobiográfica en epilepsia del lóbulo temporal / Autobiographical memory in temporal lobe epilepsy

La epilepsia del lóbulo temporal (ELT) es un tipo de epilepsia focal que se caracteriza por crisis parciales complejas y secundariamente generalizadas; es una enfermedad de difícil control, es decir que no responde adecuadamente al manejo farmacológico. Otra característica es su comorbilidad con trastornos cognitivos secundarios a la frecuencia e intensidad de las crisis epilépticas, afectándose especialmente los procesos mnésicos. Es probable que el paciente con ELT tenga dificultades en la memoria autobiográfica (MA); sin embargo, la evaluación neuropsicológica que se realiza en este tipo de epilepsia, no refleja las quejas que el paciente refiere acerca de su MA, aspecto que altera su calidad de vida. En el presente artículo se exponen los modelos explicativos de la MA así como los métodos de evaluación más usados para este tipo de memoria y, finalmente, se revisan investigaciones acerca de la MA en pacientes con ELT.

Temporal lobe epilepsy (TLE) is a type of focal epilepsy that is mainly characterized by complex secondarily generated seizures. It is a difficult illness to control because it doesn't respond to pharmacological treatment. Another feature of this type of epilepsy is its comorbidity with cognitive disorders that mainly affect memory and depend on the frequency and intensity of seizures. Patients with TLE normally have problems with autobiographical memory (AM), especially in cases where the etiology is hippocampal sclerosis (HS). However, neuropsychological evaluations of this type of epilepsy do not reflect patient complaints about their autobiographical memory, a factor which affects quality of life. In this paper we present the explanatory models of RAM, set out the most common methods used to assess it, and finally research on AM for patients with TLE is revised.

Amnesia retrógrada aislada: descripción clínica y neuroimágenesde un caso / Isolated retrograde amnesia: clinical description and neuroimages of a case

La amnesia retrógrada aislada es un déficit neuropsicológico poco común y sus características clínicas, etiológicas,imagenológicas y de recuperación han sido poco documentadas. El presente artículo reporta el casoclínico de una paciente de 28 años de edad, residente en Medellín, Colombia, quien posterior a un secuestro,sufre pérdida de la memoria remota. Se le practicó una evaluación neuropsicológica, además se le realizaronestudios de neuroimagen estructural y funcional, con el fin de caracterizar un posible daño neurológico...

Fish oil provides a sustained antiamnesic effect after acute, transient forebrain ischemia but not after chronic cerebral hypoperfusion in middle-aged rats.

We reported that fish oil (FO) abolishes retrograde amnesia consistently following transient global cerebral ischemia (TGCI) in young rats, provided it covered the first days prior to and after ischemia. Here, we further evaluated whether FO given post-ischemia in older rats (15-18 months old) is equally effective in facilitating memory recovery. We also tested whether the antiamnesic effect of FO observed after TGCI can be reproduced after chronic cerebral hypoperfusion (CCH). FO (300 mg/kg docosahexaenoic acid [DHA]) was delivered orally 4h after TGCI and continued once per day for 9 days. In the CCH group, FO treatment began soon after the first stage of 4-VO/ICA and continued daily for 43 days. Two weeks after surgery, the animals were tested for retrograde memory performance across 5 weeks. Both TGCI and CCH caused persistent memory impairment and hippocampal and cortical neurodegeneration. TGCI-induced retrograde amnesia was reversed by FO, an effect that was sustained for at least 5 weeks after discontinuing treatment. In contrast, the memory deficit caused by CCH remained unchanged after FO treatment. Both hippocampal and cortical damage was not alleviated by FO. We conclude that the FO-mediated antiamnesic effect following TGCI can be extended to older rats, even when the treatment begins 4h postischemia. Such efficacy was not reproduced after CCH. Therefore, the present results support the notion that FO may have therapeutic utility in treating learning/memory dysfunction after acute/transient cerebral ischemia and suggest that such benefits may not apply when a state of chronic cerebrovascular insufficiency is present.

Rehabilitación neuropsicológica en un caso de amnesia retrógrada aislada / Neuropsychological rehabilitation in an isolated case of retrograde amnesia

La amnesia retrógrada aislada es un déficit neuropsicológico poco común y el empleo de terapia de rehabilitación neuropsicológica no ha sido estudiado ni planteado para estos pacientes. El presente artículo documenta el caso clínico de CE, una paciente de 28 años de edad, residente en Medellín, Colombia, quien posterior a un secuestro, sufre pérdida de la memoria remota. Se le practicó una evaluación neuropsicológica, y estudios de neuroimagen estructural. Posteriormente, se propuso e implementó un plan de rehabilitación neuropsicológica enfocado en la recuperación de la memoria semántica. Al terminar la intervención se encontró mejoría a nivel cognitivo y funcional, con incremento significativo en las habilidades mnésicas y neurolingüísticas, en la comprensión de su entorno y el desempeño en las actividades cotidianas.

Isolated retrograde amnesia is a rare neuropsychological deficit and neuropsychological rehabilitation therapy has not been studied or proposed for these patients. This article documents the case of CE, a 28-year-old female patient, resident in Medellin, Colombia, who suffers remote memory loss after being kidnapped. Neuropsychological assessment and structural neuroimaging studies was performed. Then, a neuropsychological rehabilitation plan focused on semantic memory retrieval was planned and implemented. After the intervention, cognitive and functional improvement was found, with significant increase in mnemonic and neurolinguistic skills, also in understanding of her environment and her performance in daily activities.