1.
Memory enhancement induced by hypothalamic/fornix deep brain stimulation.
Hamani, C, McAndrews, MP, Cohn, M, Oh, M, Zumsteg, D, Shapiro, CM, Wennberg, RA, Lozano, AM
Annals of neurology. 2008;(1):119-23
Abstract
Bilateral hypothalamic deep brain stimulation was performed to treat a patient with morbid obesity. We observed, quite unexpectedly, that stimulation evoked detailed autobiographical memories. Associative memory tasks conducted in a double-blinded "on" versus "off" manner demonstrated that stimulation increased recollection but not familiarity-based recognition, indicating a functional engagement of the hippocampus. Electroencephalographic source localization showed that hypothalamic deep brain stimulation drove activity in mesial temporal lobe structures. This shows that hypothalamic stimulation in this patient modulates limbic activity and improves certain memory functions.
2.
Olfaction as a traumatic reminder in posttraumatic stress disorder: case reports and review.
Vermetten, E, Bremner, JD
The Journal of clinical psychiatry. 2003;(2):202-7
Abstract
BACKGROUND Memory for odors that are associated with intense emotional experiences is often strongly engraved. Odors are claimed to be more closely connected to affect than other sensory experiences. They can serve as potent contextual cues for memory formation and emotional conditioning and can also serve as cues for olfactory flashbacks. Though trauma-related smells have long been noted by clinicians to be precipitants of traumatic memories in patients with posttraumatic stress disorder (PTSD), very few reports have been published that document this. CASE REPORTS We review olfactory memories and olfactory flashbacks by presenting 3 cases that illustrate the role of olfaction in PTSD. In these cases olfaction is either a precipitant of PTSD symptoms or an important component of reexperiencing. DISCUSSION In PTSD, seemingly nonspecific cues have the potential to precipitate traumatic memories with strong emotional components. These conditioned responses in PTSD are hypothesized to be mediated by specific brain areas, i.e., amygdala, hippocampus, and orbitofrontal cortex. Questions about smells as a traumatic reminder should be part of the routine assessment of intrusive memories in PTSD. In addition, smells may have the potential to provide cues to exposure situations in therapy or to facilitate de novo conditioning.