Estudio de la memoria emocional en pacientes con epilepsia del lóbulo temporal

Resumen

Emotional episodic memory is the capacity whereby we encode, store and retrieve memories that are linked to emotional information. Patients whose emotional episodic memory capacity is impaired typically show limitations in affective events, which influence their social, familial and occupational relationships. Mesial Temporal Lobe Epilepsy is common pharmacoresistant pathology. Usually in these cases, the alternative treatment is resection of the amygdala and hippocampus. This treatment can improve the quality of life of these patients because the frequency and intensity of the crisis are usually controlled, but there may be side effects such as disorders in episodic memory and, in particular, in emotional memory. Research about emotional memory based on the study of patients where the surgical resection area is accurately delimited provides a great opportunity for the study of the relationship between this ability and its cerebral bases. In recent years the knowledge about emotional memory has substantially progressed. Nevertheless, there are still aspects related to differences between visual and verbal modalities, or type of emotion (positive, negative or neutral), that have not yet been elucidated. For this reason, the general aim of this thesis is to increase the knowledge of these characteristics of emotional memory. To that end, subject performance on episodic memory tasks was assessed: both general and emotional memories, in visual and verbal modalities, and at two stages of information processing (encoding and retrieval). Four different groups of participants were tested: 29 patients with right amygdala and hippocampus resection and 30 with left amygdala and hippocampus resection, compared with 31 medial temporal lobe refractory epilepsy patients who had not been operated on surgically, and 29 healthy participants. In summary, the results suggest that intellectual performance is not affected after surgical resection, although both visual and verbal episodic memories are impaired. Verbal episodic memory is affected primarily in patients with resection in the left region, but the visual modality does not show hemispheric specialization. When emotional information is included in the visual modality, left hippocampus and amygdala resection compromises memories of positive emotions, and right resection affects the memories of negative emotions. In case of verbal emotional memory, resection of the left hippocampus and amygdala is associated with poorer outcomes in emotional memory (positive and negative), while right surgical resection is associated with loss of usefulness of emotional information. Finally, in refractory mesial temporal lobe epilepsy patients without resection, and in the healthy population, negative emotions improve memory, compared to neutral emotions. Furthermore, we have found a percentage in the three groups of patients with severe damage in general episodic memory, higher than the healthy population. In the case of emotional memory, this percentage is higher than expected in patients with right resection for the encoding of visual emotional memory, and in patients with left resection, the severe damage is related with the encoding and retrieval of verbal emotional memory. In conclusion, these results contribute to the current understanding of emotional episodic memory in relation to its modality and emotional content, depending on the cerebral hemisphere. These results are also useful for the design and development of improved and more accurate assessments and rehabilitation programs in clinical interventions in accordance with the specific characteristics of episodic emotional memory involved.