Role Of Hippocampus Research Articles

Research on the role of hippocampus in memory consolidation

The length of time needed to recover memories in the hippocampus area varies greatly across the existing theories of system-level consolidation. These competing hypotheses do, however, have connections. The standard consolidation theory, multiple trace theory, and scene construction theory are the three existing models that are examined in this study. After reexamining their features, the authors test whether the three models can be integrated in terms of trace duration and function. It is better to think of the hippocampus's contribution to system-level consolidation as a functional transition from retention to rebuilding through time rather than just a question of persistence. The involvement of the hippocampus in memory retrieval may be fitted into a more thorough model in terms of functional transformation since the two functions, retention and reconstruction, are of equal significance and can scarcely be divided into two sections.

Role of hippocampus and orbitofrontal cortex in the association of interdependent self-construal with an acute stress response

Empirical evidence indicates that high interdependent self-construal (InterSC) is correlated with exaggerated acute stress responses; however, the underlying neural correlates remain unclear. Considering the regulatory effect of the prefrontal cortex and limbic system on the acute stress response, the primary aim of this study was to investigate the role of the orbitofrontal cortex (OFC) and hippocampus (HIP) in the relationship between InterSC and acute stress responses. Forty-eight healthy college students underwent a modified version of the Montreal imaging stress task (MIST), while brain activity was recorded using functional magnetic resonance imaging (fMRI). Participants' saliva samples and subjective stress feelings were collected before, during, and after the MIST. Additionally, participants’ self-construal was measured using questionnaires. Results revealed that InterSC was positively correlated with the activation of OFC, which, in turn, was associated with higher subjective stress feelings. A higher InterSC was also significantly associated with an enhanced salivary cortisol response in those with lower HIP activity. Furthermore, the HIP moderated the indirect effect of InterSC on subjective stress feelings by moderating the effect of InterSC on neural activity in the OFC. This indicated the mediation of the OFC was stronger in those with higher neural activity in the HIP than in those with lower activity in the HIP. In summary, the current study proposed an important role of the OFC-HIP regions in the relationship between InterSC and acute stress responses, making contribution to broadening the field of personality and stress and deepening our understanding of individual differences in acute stress responses.

Representations of Complex Contexts: A Role for Hippocampus.

The hippocampus plays a critical role in supporting episodic memory, in large part by binding together experiences and items with surrounding contextual information. At present, however, little is known about the roles of different hippocampal subfields in supporting this item-context binding. To address this question, we constructed a task in which items were affiliated with differing types of context-cognitive associations that vary at the local, item level and membership in temporally organized lists that linked items together at a global level. Participants made item recognition judgments while undergoing high-resolution fMRI. We performed voxel pattern similarity analyses to answer the question of how human hippocampal subfields represent retrieved information about cognitive states and the time at which a past event took place. As participants recollected previously presented items, activity patterns in the CA23DG subregion carried information about prior cognitive states associated with these items. We found no evidence to suggest reinstatement of information about temporal context at the level of list membership, but exploratory analyses revealed representations of temporal context at a coarse level in conjunction with representations of cognitive contexts. Results are consistent with characterizations of CA23DG as a critical site for binding together items and contexts in the service of memory retrieval.

The role of hippocampus in memory reactivation: an implication for a therapeutic target against opioid use disorder.

Purpose of the reviewThe abuse of opioids induces many terrible problems in human health and social stability. For opioid-dependent individuals, withdrawal memory can be reactivated by context, which is then associated with extremely unpleasant physical and emotional feelings during opioid withdrawal. The reactivation of withdrawal memory is considered one of the most important reasons for opioid relapse, and it also allows for memory modulation based on the reconsolidation phenomenon. However, studies exploring withdrawal memory modulation during the reconsolidation window are lacking. By summarizing the previous findings about the reactivation of negative emotional memories, we are going to suggest potential neural regions and systems for modulating opioid withdrawal memory.Recent findingsHere, we first present the role of memory reactivation in its modification, discuss how the hippocampus participates in memory reactivation, and discuss the importance of noradrenergic signaling in the hippocampus for memory reactivation. Then, we review the engagement of other limbic regions receiving noradrenergic signaling in memory reactivation. We suggest that noradrenergic signaling targeting hippocampus neurons might play a potential role in strengthening the disruptive effect of withdrawal memory extinction by facilitating the degree of memory reactivation.SummaryThis review will contribute to a better understanding of the mechanisms underlying reactivation-dependent memory malleability and will provide new therapeutic avenues for treating opioid use disorders.

The relationship of bioelectric activity and structural changes in the hippocampus at pharmacoresistant temporal lobe epilepsy

Background. Epilepsy is one of the most common neurological diseases globally. The unified concept about the role of hippocampus in the development of pharmacoresistant temporal lobe epilepsy is currently missing. Patients with pharmacoresistant temporal lobe epilepsy is often carried out by invasive electrocorticography to identify an epileptic focus. Registration of bioelectric activity of the hippocampus and comparison of data from the MRI pattern of the patient will determine the neurophysiological correlates of structural changes in hippocampus.Objective. The aim of the work was to determine the neurophysiological correlates of structural changes in the hippocampus in patients with focally caused temporal lobe epilepsy.Design and methods. The study was based on the analysis of the results of extraoperative invasive monitoring of the bioelectrical activity of the cortex and hippocampal complex, performed in 19 patients with focally caused drug-resistant epilepsy. The quantitative analysis included 34 tracks of hippocampal activity.Results. A distinctive feature of the bioelectrical activity of the hippocampal complex with its structural damage is the stable dominance of delta activity, which makes up 40–45 % of the total spectrum power. When the hippocampal complex is included in the epileptic system, high-index epileptiform activity is recorded. In the absence of structural damage to the hippocampal complex, the pattern is predominantly formed by the activity of theta and alpha frequency ranges. However, in the group of patients with the absence of a neuroimaging picture of sclerotic changes in the hippocampus, in 63 % of cases, a neurophysiological pattern of “prolapse” was recorded on the electrocorticogram. The spontaneous activity of the hippocampus had a low coherent relationship with the parameters of activity in the cortex of the ipsilateral and contralateral temporal lobes.Conclusions. The electrophysiological correlate of MR-positive structural changes in the hippocampal complex in drug-resistant epilepsy is the pattern of “loss of bioelectric activity”. Spontaneous hippocampal activity is generated independently of activity in the cortex of the ipsilateral and contralateral temporal lobes.

The role of hippocampus and amygdala morphology in memory bias of learned fear in youth with chronic pain

Exaggerated recall of pain may pose a risk for pain persistence and elevated pain-related distress. In adults with chronic pain, such discrepancy (or memory bias) has been correlated to hippocampal morphology. However, this has not been examined in youth with chronic pain nor applied to the recall of fear and negative affect, and to amygdala morphology, considering its involvement in threat processing. This study therefore aims to examine whether hippocampal and amygdala shape is related to a biased recall of threat-safety learning in youth with chronic pain. T1-weighted MR images of 85 youth were analyzed (age M=15.6±0.9), of which 54 had chronic pain. The Screaming Lady paradigm was used for threat conditioning. Follow-up memory interviews assessed recalled fear and unpleasantness of conditioned stimuli (threat/CS+, safe/CS-). A discrepancy score was calculated between actual and recalled fear/negative affect (n=60, including n=37 patients). Permutation-based statistics focused on group differences in hippocampus and amygdala morphology using vertex-based shape analysis, as well as on correlations with discrepancy scores (voxel-based thresholding, corrected for multiple comparisons). We found an overall negative memory bias only for unpleasantness of the CS+. On an individual level, 20% had a negatively-biased recall for unpleasantness of the CS+, and 35% for fear of the CS+. Analyses showed no group differences in hippocampal or amygdala shape displacement. Nevertheless, there was a negative correlation between memory bias in fear for the CS+ and right amygdala shape displacement, indicating that a more negative fear-related memory bias is associated with thinning of this region. No other correlations were observed. Our findings revealed that a recall bias for learned fear is related to amygdala morphology in youth. Youth with chronic pain, however, did not differ in amygdala morphology compared to controls. NIH R01HD083270 to LE Simons.

Altered hippocampal functional connectivity patterns in patients with cognitive impairments following ischaemic stroke: A resting-state fMRI study

BackgroundIschemic stroke with cognitive impairment is a considerable risk factor for developing dementia. Identifying imaging markers of cognitive impairment following ischemic stroke will help to develop prevention strategies against post-stroke dementia. MethodsWe investigated the hippocampal functional connectivity (FC) pattern following ischemic stroke, using resting-state fMRI (rs-fMRI). Thirty-three cognitively impaired patients after ischemic stroke and sixteen age-matched controls with no known history of neurological disorder were recruited for the study. No patient had a direct ischaemic insult to hippocampus on the examination of brain imaging. Seven subfields of hippocampus were used as seeds region for FC analyses. ResultsAcross all hippocampal subfields, FC with the inferior parietal lobule was reduced in stroke patients as compared with healthy controls. This decreased FC included both supramarginal gyrus and angular gyrus. The FC of hippocampal subfields with cerebellum was increased. Importantly, the degree of the altered FC between hippocampal subfields and inferior parietal lobule was associated with their impaired memory function. ConclusionOur results demonstrated that decreased hippocampal-inferior parietal lobule connectivity was associated with cognitive impairment in patients with ischemic stroke. These findings provide novel insights into the role of hippocampus in cognitive impairment following ischemic stroke.

Did Proust predict the existence of episodic memory?

Cognitive psychologists have often discussed the idea that when Proust used in his books the concept of involuntary memories, which could be retrieved by an odor or a taste, he was in fact predating the notion of modern episodic memory. Since the publication of his famous "In Search of Lost Time", considerable progress has been made on our understanding of various types of memory and of the mechanisms involved in different brain circuits and synapses responsible for their long-term storage. This review will focus on the role of hippocampus in episodic memory, including its role in encoding time and various elements of episodes, in particular olfactory information. Our conclusion is that Proust did indeed predict the existence of episodic memory, although he did not realize that, in addition to remembering things past, memory is also used to predict the future.

Searching for Semantic Knowledge: A Vector Space Semantic Analysis of the Feature Generation Task.

A recent neuropsychological study found that amnesic patients with hippocampal damage (HP) and severe declarative memory impairment produce markedly fewer responses than healthy comparison (CO) participants in a semantic feature generation task (Klooster and Duff, 2015), consistent with the idea that hippocampal damage is associated with semantic cognitive deficits. Participants were presented with a target word and asked to produce as many features of that word as possible (e.g., for target word “book,” “read words on a page”). Here, we use the response sequences collected by Klooster and Duff (2015) to develop a vector space model of semantic search. We use this model to characterize the dynamics of semantic feature generation and consider the role of the hippocampus in this search process. Both HP and CO groups tended to initiate the search process with features close in semantic space to the target word, with a gradual decline in similarity to the target word over the first several responses. Adjacent features in the response sequence showed stronger similarity to each other than to non-adjacent features, suggesting that the search process follows a local trajectory in semantic space. Overall, HP patients generated features that were closer in semantic space to the representation of the target word, as compared to the features generated by the CO group, which ranged more widely in semantic space. These results are consistent with a model in which a compound retrieval cue (containing a representation of the target word and a representation of the previous response) is used to probe semantic memory. The model suggests that the HP group's search process is restricted from ranging as far in semantic space from the target word, relative to the CO group. These results place strong constraints on the structure of models of semantic memory search, and on the role of hippocampus in probing semantic memory.

A complex relation between depression and multiple sclerosis: a descriptive review.

Multiple sclerosis (MS) is a demyelinating neurodegenerative disease that affects central nervous system (CNS). MS patients are more likely to develop depressive symptoms than patients with other chronic diseases. In this review, we have analysed if there is a correlation between brain lesions (BL), structural damage (SD) and depressive symptoms (DS). We Searched on PubMed and Web of Science databases and screening references of included studied and some review article for additional citations. From initial 745 studies, only 9 met the inclusion criteria. All studies conducted research on 389 patients with MS associated with DS and 120 HC (healthy controls). The selected researches highlighted the involvement of limbic system, the role of hippocampus and the impact of brain lesions on the emotional status of MS patients. In the genesis of depression are implicated many mechanisms including genetic, biochemical, immunological and psychosocial factors, even if a prominent role in the onset of DS seem to be associated with structural and functional brain alterations.

The role of hippocampus in the retrieval of autobiographical memories in patients with amnestic Mild Cognitive Impairment due to Alzheimer's disease.

The role of the hippocampus and neocortical areas in the retrieval of past memories in pre-dementia Alzheimer's disease (AD) patients was investigated. The aim was to assess whether the hippocampus has a temporary role in memory trace formation, according to the Cortical Reallocation Theory (CRT), or whether it continuously updates and enriches memories, according to the Multiple Trace Theory. According to the former theory, hippocampal damage should affect more recent memories, whereas the association cortex is expected to affect memories of the entire lifespan. In the second case, damage to either the hippocampus or the association cortices should affect memories of the entire lifespan. Seventeen patients with amnestic Mild Cognitive Impairment due to AD were submitted to autobiographical (i.e., episodic and semantic personal) memory assessment. Patients underwent MRI for the acquisition of T1-weighted brain volumes. Voxel-based morphometry was used to assess correlations between grey matter (GM) volumes and autobiographical memory. Correlation analyses revealed a strict association between GM volumes in the hippocampus and patients' ability to retrieve the most recent but not the oldest autobiographical memories in both aspects, episodic and semantic. Moreover, patients' GM volumes in the pre-frontal and temporal polar areas were associated with recollection of episodic and semantic events, respectively. Finally, GM volumes in the precuneus and occipital cortex were associated with retrieval of the most recent episodic events. These findings indicate that the hippocampus has a specific time-dependent role; thus, they support the CRT.

Two strategies used to solve a navigation task: A different use of the hippocampus by males and females? A preliminary study in rats

Abstract There is abundant research (both in rodents and in humans) showing that males and females often use different types of information in spatial navigation. Males prefer geometry as a source of information, whereas females tend to focus on landmarks (which are often near to a goal objects). However, when considering the role of the hippocampus, the research focuses primarily on males only. In the present study, based on Rodríguez, Torres, Mackintosh, and Chamizo’s (2010, Experiment 2) navigation protocol, we conducted two experiments, one with males and another with females, in order to tentatively evaluate the role of the dorsal hippocampus in the acquisition of two tasks: one based on landmark learning and the alternate one on local pool-geometry learning. Both when landmark learning and when geometry learning, Sham male rats learned significantly faster than Lesion male animals. This was not the case with female rats in geometry learning. These results suggest that the dorsal hippocampus could play an important role in males only.

The role of the hippocampus in object discrimination based on visual features.

The role of rodent hippocampus has been intensively studied in different cognitive tasks. However, its role in discrimination of objects remains controversial due to conflicting findings. We tested whether the number and type of features available for the identification of objects might affect the strategy (hippocampal-independent vs. hippocampal-dependent) that rats adopt to solve object discrimination tasks. We trained rats to discriminate 2D visual objects presented on a computer screen. The objects were defined either by their shape only or by multiple-features (a combination of filling pattern and brightness in addition to the shape). Our data showed that objects displayed as simple geometric shapes are not discriminated by trained rats after their hippocampi had been bilaterally inactivated by the GABAA-agonist muscimol. On the other hand, objects containing a specific combination of non-geometric features in addition to the shape are discriminated even without the hippocampus. Our results suggest that the involvement of the hippocampus in visual object discrimination depends on the abundance of object's features.

Blockade of the orexin receptors in the CA1 region of hippocampus decreased the lateral hypothalamic-induced antinociceptive responses in the model of orofacial formalin test in the rats

The role of hippocampus and lateral hypothalamus (LH) in modulation of formalin-induced nociception has been established. The present study aims to examine the role of orexin receptors in the Cornu Ammonis 1 (CA1) region of hippocampus in modulation of the LH-induced antinociception in the orofacial formalin test. Male Wistar rats were unilaterally implanted with two cannulae into the LH and CA1. Intra-LH microinjection of carbachol was done 5min after intra-CA1 administration of SB-334867 (OX1R antagonist) or TCS OX2 29 (OX2R antagonist). After 5min, 50μl of 1% formalin was subcutaneously injected into the upper lip for inducing the nociceptive behaviors. Solely intra-LH administration of carbachol reduced early and late phases of formalin-induced orofacial nociception in a dose-dependent manner. The antinociception evoked by intra-LH injection of carbachol (0.5μl of 250nM carbachol) was antagonized by intra-CA1 administration of 0.5μl of 3, 10 and 30nM solutions of SB-334867 or TCS OX2 29 during the early and late phases of orofacial formalin test. This effect was more remarkable during the late phase in comparison to the early phase. In addition, anti-analgesic effect of SB-334867 was more than TCS OX2 29 during the early and late phases. The results suggest the interpretation that a neural pathway from the LH to the CA1 probably contributes to the modulation of formalin-induced orofacial nociception through recruitment of both CA1 orexin receptors. Clinical studies are recommended to study the probable effectiveness of orexinergic system in modulation of the orofacial nociceptive responses.

The regulation of SKF38393 on the signaling pathway of dopamine D1 receptor in hippocampus during chronic sleep deprivation.

Hippocampal functions are sensitive to sleep deficiency. Dopamine D1 receptor (D1R) in hippocampus can regulate the expression of cAMP response element binding protein (CREB) through PKA, MAPK and phosphoinositide pathway, but which pathway plays the major role in hippocampus during Chronic sleep deprivation (CSD) is unclear. The CSD model was created, SKF rats were administered the D1R agonist (SKF38363), and hippocampus from each animal was dissected for following molecular detection. The gene and protein levels of CREB and key molecules in D1R pathways were measured by real-time PCR and western blotting, respectively. Both the gene and protein expression of CREB in hippocampus decreased by CSD and improved significantly by SKF38393 (p<0.05). Both the gene and protein expression of PKA in hippocampus decreased by CSD and improved significantly by SKF38393 (p<0.05). SKF38393 just significantly improved the gene level of CaMK IV and the protein level of p-CaMK IV (p<0.05) in CSD rats, but it cannot improve the protein expression of ERK1/2 and p-ERK1/2. CSD significantly decreased the expression of CREB in hippocampus. As the key molecules, PKA and CaMK IV play an important role during the improvement of hippocampus by the activation of D1R, and this process might be improved during CSD through the PKA and phosphoinositide pathway.

РОЛЬ ГИППОКАМПА В РАЗВИТИИ БИ-, ПОЛИЛИНГВИЗМА

The influence of hippocampus is researched in the article. The purpose of the paper is the description of hippocampus, its functions in foreign language teaching (short- and long-term memory, analyze, synthesis and memorizing information, logical thinking, forming associated words combinations, skills to product writing and oral speech, etc. Hippocampus is a division (gyrus) of the brain, it has influence to man’s ability to learn foreign languages. Hippocampus is described in the article in aspects of its functions, periods of growing, methods of its development and reasons of its reduction. The role of hippocampus in formation of bilingual/multilingual person is described in the research [1. С. 162].

Preconditioning of Spatial and Auditory Cues: Roles of the Hippocampus, Frontal Cortex, and Cue-Directed Attention.

Loss of function of the hippocampus or frontal cortex is associated with reduced performance on memory tasks, in which subjects are incidentally exposed to cues at specific places in the environment and are subsequently asked to recollect the location at which the cue was experienced. Here, we examined the roles of the rodent hippocampus and frontal cortex in cue-directed attention during encoding of memory for the location of a single incidentally experienced cue. During a spatial sensory preconditioning task, rats explored an elevated platform while an auditory cue was incidentally presented at one corner. The opposite corner acted as an unpaired control location. The rats demonstrated recollection of location by avoiding the paired corner after the auditory cue was in turn paired with shock. Damage to either the dorsal hippocampus or the frontal cortex impaired this memory ability. However, we also found that hippocampal lesions enhanced attention directed towards the cue during the encoding phase, while frontal cortical lesions reduced cue-directed attention. These results suggest that the deficit in spatial sensory preconditioning caused by frontal cortical damage may be mediated by inattention to the location of cues during the latent encoding phase, while deficits following hippocampal damage must be related to other mechanisms such as generation of neural plasticity.

EP 123. Impaired conflict processing in patients with hippocampal sclerosis

Introduction Hippocampal sclerosis (HS) frequently underlies temporal lobe epilepsy. Patients often suffer from refractory epileptic seizures, but episodic memory deficits, depressive syndromes or impaired special navigation are also common symptoms. Much less is known about the role of the hippocampus for conflict processing. Patients with impaired conflict processing show specific behavioral deficits. They lack goal-directed behavior, are more distractible or have personality characteristics such as unsteadiness, emotional instability, with frequent and rapid mood changes. Early evidence for a hippocampal role in conflict processing comes from Gray’s 1982 model of anxiety, which suggests that the hippocampus supports avoidance behavior during approach-avoidance-conflicts. In addition, the hippocampus is thought to be important for inhibitory learning, a fundamental process that might modulate higher cognitive functions like memory or even conflict processing ( Chan et al., 2001 ). A recent fMRI-EEG study confirmed a role of the human hippocampus for conflict processing by showing hippocampal activity during cognitive conflicts in an auditory stroop task ( Oehrn et al., 2015 ). Here we investigate how hippocampal damage relates to deficits in conflict processing. Methods Patients with temporal lobe epilepsy and HS, patients with TLE and a temporolateral lesion and 27 healthy controls perform the auditory stroop task. Subjects listen to the words “high”, “low” and “good” (semantic aspect) in a low or high pitch (phonetic aspect). Semantic and phonetic aspects either matched (congruent condition) or contradicted (incongruent condition). Results So far, we collected data from two patients with HS and 27 healthy controls. Patients show higher conflict-related slowing of response time (166 ms ± 94) than healthy controls (68 ms ± 53). Patients also show less correct responses during conflict (61% ± 51) compared to non-conflict condition (86% ± 19). However, healthy controls responded correctly in most trials during incongruent (99% ± 1) and congruent condition (95% ± 8). Conclusions The preliminary descriptive data indicate conflict-related slowing of information processing in patients with hippocampal damage. The findings can further our understanding of the role of the hippocampus for conflict processing. It may also help to explain psychiatric comorbidities in patients with temporal lobe epilepsy.

Role of hippocampus in polymodal-cue guided tasks in rats

To examine how signals from different sensory modalities are integrated to generate an appropriate goal-oriented behavior, we trained rats in an eight-arm radial maze to visit a cue arm provided with intramaze cues from different sensory modalities, i.e. visual, tactile and auditory, in order to obtain a reward. When the same rats were then examined on test trials in which the cue arm contained one of the stimuli that the animals were trained with (i.e. light, sound or rough sheet), they showed a significant impairment with respect to the performance on the polymodal-cue task. The contribution of the dorsal hippocampus to the acquisition and retention of polymodal-cue guided task was also examined. We found that rats with dorsal hippocampal lesions before training showed a significant deficit in the acquisition of polymodal-cue oriented task that improved with overtraining. The selective lesion of the dorsal hippocampus after training disrupted memory retention, but the animals' performance improved following retraining of the polymodal task. All hippocampal lesioned rats displayed an impaired performance on the unimodal test. These findings suggest that the dorsal hippocampus contributes to the processing of multimodal sensory information for the associative memory formation and consolidation.

Expression changes of indoleamine 2, 3-dioxy-genase in the hippocampus of rat with post-traumatic stress disorder

Objective To observe the expression of indoleamine 2, 3-dioxy-genase(IDO) in hippocampus of rats with posttraumatic stress disorder (PTSD) and the protective effect of IDO inhibitor on neurons, and to explore the role of IDO in the pathogenesis of PTSD. Methods Adult male Wistar rats were randomly divided into the normal control group, PTSD model group and IDO inhibitor treatment group. The expression of IDO was detected by immunohistochemistry, RT-PCR and Western-blot. The apoptosis of rat hippocampal neurons was assayed by Tunel staining. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected by ELISA. Moreover behavioral evaluation was performed, including central residence time, percentage of open arm residence time and stage latency. Results Comparing with the control group, PTSD rats showed decreased central residence time ((22.65±1.54)s), decreased percentage of open arm residence time((10.55± 1.96)%), prolonged stage latency ((56.38±4.21) s) (P <0.05), increased TNF-α ((8.58±0.6) pg/ml), IL-6 ((15.72±1.42)pg/ml) and IDO mRNA (0.8278±0.0796), increased IDO protein (1.2329±0.1148) expression and apoptosis rate((81.47±6.86)%) in hippocampus (P <0.05)(P <0.05). However, rats treated with IDO inhibitor showed increased central residence time((30.78±3.20)s), increased percentage of open arm residence time((10.55±1.96)%), shortened stage latency ((56.38 ±4.21)s), meanwhile reduced expression of TNF-α((3.69±0.41)pg/ml), IL-6((7.45±0.58)pg/ml), IDO mRNA(0.2236 ±0.0387) and IDO protein(0.4235±0.0411) was detected in hippocampus(P <0.05). Apoptosis rate ((42.54± 3.98)%) was also decreased in hippocampus(P <0.05). Conclusion The content of TNF-α, IL-6 and IDO are increased significantly in the hippocampus of PTSD rats. IDO may participate in the pathogenesis of PTSD, and the IDO inhibitor may play a neuroprotective role in hippocampus of PTSD. Key words: Post-traumatic stress disorder; Indoleamine 2, 3-dioxy-genase; Tumor necrosis factor-α; Interleukin-6