The **hippocampus** is a bilateral subcortical structure of the medial temporal lobe, essential for **explicit memory** (conscious, narrative, autobiographical) and for the temporal integration of experiences. Without a functional hippocampus, we cannot form new autobiographical memories; experiences remain in implicit memory but are not integrated into the conscious narrative.
**In acute and chronic trauma**: during severe traumatic experiences, high levels of cortisol and glutamate can **inhibit hippocampal function**. The consequence: the traumatic event is registered by the amygdala (implicit emotional memory) but not by the hippocampus (explicit narrative memory). This is why many survivors remember 'feeling something terrible' without being able to narrate exactly what happened —especially in early trauma—.
**Neuroscientific findings**: MRI studies in PTSD victims show a **smaller hippocampal volume** compared to controls. Causality is still debated (does trauma reduce the hippocampus or does a smaller hippocampus predispose to trauma?), but the correlation is robust. Studies with Holocaust survivors and their descendants show similar patterns.
**Clinical implication**: explains the phenomenon of **'frozen memory'** in trauma —images without clear temporal context, the sensation of 'it's still happening' even though the event was decades ago, difficulty integrating the trauma into the autobiographical narrative—. Therapeutic work seeks, in part, to restore hippocampal integration: to place the trauma in its time, in its context, as an event that happened and ended.
**Good neuroplasticity news**: the hippocampus is one of the brain structures with the greatest capacity for adult neurogenesis —it produces new neurons throughout life—. Exercise, adequate sleep, BDNF (neurotrophic factor), and effective therapy promote this neurogenesis. Trauma healing includes documentable hippocampal reconstruction.
Evidence and Contemporary Voices
The hippocampus, a key limbic structure in the formation and retrieval of explicit memories, shows volumetric reduction in post-traumatic stress disorder (PTSD) according to a meta-analysis by Kitayama et al. (2005), who analyzed MRIs of 487 participants, finding correlations between smaller hippocampal volume and symptomatic severity. Bremner (2006), at Yale University, demonstrated through neuroimaging that exposure to chronic trauma inhibits hippocampal neurogenesis via a hyperactive HPA axis, leaving fragmented memories without temporal integration (Bremner, 2006). Longitudinal studies by Yehuda et al. (2015) at Mount Sinai Hospital reveal that 9/11 survivors with PTSD exhibit an atrophied hippocampus, with partial recovery after prolonged cognitive-behavioral therapy. Van der Kolk (2014) integrates these findings into his triune model, where the hippocampus 'freezes' traumatic events outside of narrative context, preventing their autobiographical processing. Functional neuroimaging by Shin et al. (2006) confirms hippocampal hypoactivation during retrieval of traumatic memories in Vietnam veterans.
Verifiable Citations
- "The hippocampus plays a central role in the contextual encoding of emotional memories, inhibited in PTSD by elevated glucocorticoids." — J. Douglas Bremner, Traumatic stress: Effects on the brain (2006, p. 147).
- "Smaller hippocampal volume is consistently associated with intrusion and avoidance symptoms in PTSD." — Nobuo Kitayama, Lisa M. Vaccarino, Charles B. Nemeroff, Magnetic resonance imaging (MRI) measurement of hippocampal volume in posttraumatic stress disorder: A meta-analysis (2005).
Researchers and Experts
- J. Douglas Bremner — Yale University — neurobiology of trauma and hippocampal atrophy
- Rachel Yehuda — Mount Sinai Hospital — epigenetics of trauma and neuroimaging in PTSD
- Bessel van der Kolk — Boston University — neuroaffective integration of trauma
- Scott M. Shin — Harvard Medical School — fMRI in traumatic memory recovery
Auditable Sources
Additional research generated with consultation of academic sources (Perplexity Sonar Pro). Citations and URLs are the responsibility of their original source; verify before formally citing.
Bibliography
- The Body Keeps the Score — Bessel van der Kolk. Eleftheria, 2015.
- Holocaust Exposure Induced Intergenerational Effects on FKBP5 Methylation — Rachel Yehuda et al.. Biological Psychiatry, 80(5), 372-380, 2016.
These books are in the reference library that nourishes Constelando el Origen.
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Related terms
Amygdala and Fear Response
A key subcortical brain structure for detecting and responding to danger. In trauma, it becomes hypersensitive, generating emotional reactivity to stimuli that the cortex has not yet processed.
View entryFKBP5 (Stress Gene)
A gene that regulates the sensitivity of the glucocorticoid receptor to cortisol. Its epigenetic modifications are one of the central findings in the transgenerational transmission of trauma.
View entryComplex Trauma (C-PTSD)
A disorder formulated by Judith Herman (1992): trauma resulting from prolonged exposure to abuse, neglect, or severe dysfunctional relationships, especially in childhood. Different from classic PTSD.
View entryBDNF (Neurotrophic Factor) and Trauma
Brain-Derived Neurotrophic Factor: a key protein for neuronal plasticity. Its expression is diminished in victims of early trauma and their descendants, recovering with specific interventions.
View entryA session that names what hurts
If you recognize this dynamic in your own story, a Family Constellation can reveal where it comes from and what movement brings it into order. Daniela respectfully accompanies each case.
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