Hippocampal glutamate concentration predicts cerebral theta oscillations during cognitive processing

Gallinat, Jürgen; Kunz, Dieter; Senkowski, Daniel; Kienast, Thorsten; Seifert, F.; Schubert, Florian; Heinz, Andreas

doi:10.1007/s00213-006-0397-0

Cited by 63 publications

(49 citation statements)

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“…32 Also in human beings, several studies suggest a link between decreased glutamatergic neurotransmission and hippocampal functions. 33 When healthy subjects are treated with NMDA antagonists such as phencyclidine or ketamine, declarative as well as explicit memory functions are impaired. 34,35 Blood pressure did not only affect hippocampal glutamate status.…”

Section: Discussionmentioning

confidence: 99%

The impact of blood pressure on hippocampal glutamate and mnestic function

et al. 2010

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Hypertension is associated with an increased risk of cognitive decline, which is generally regarded as a consequence of advanced cerebral atherosclerosis. Many hypertensive patients, however, suffer from cognitive decline long before they have any signs of cerebrovascular disease. Therefore, this study examines direct effects of blood pressure on neurotransmitter status in the hippocampus, a vulnerable cerebral structure relevant for memory consolidation. Absolute glutamate concentration and N-acetylaspartate (NAA) concentration as an alternative marker of neuronal integrity were determined in the hippocampus and the cerebral cortex (anterior cingulate cortex; ACC) by 3-T proton magnetic resonance spectroscopy in 16 probands without any history of cerebrovascular disease. Memory function was tested by the auditory verbal learning test (AVLT) and the rivermead behavioural memory test (RBMT). Arterial stiffness was assessed by augmentation index (AI). Mean arterial pressure showed a significant negative age-adjusted correlation to absolute glutamate concentrations in the hippocampus (R ¼ À0.655, P ¼ 0.011), but not in the ACC. There was no significant correlation of mean arterial pressure and NAA in either hippocampus or ACC. AI did not affect hippocampal glutamate. Moreover, there was a significant negative correlation between mean arterial pressure and AVLT (r ¼ À0.558, P ¼ 0.025) and RBMT score (r ¼ À0.555, P ¼ 0.026). There is an inverse relation between blood pressure and the concentration of hippocampal glutamate. Glutamate is essential for long-term potentiation, the neurobiological correlate for memory formation in the hippocampus. Thus, hypertension-associated cognitive decline may not only be mediated by structural atherosclerotic wall changes, but also by functional changes in neurotransmission.

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Section: Discussionmentioning

confidence: 99%

The impact of blood pressure on hippocampal glutamate and mnestic function

et al. 2010

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“…The relative insensitivity of our method against contributions by aspartate, the resonances of which are close to the region of the glutamate C4 resonance of interest, has also been shown previously. 41 To correct the Typical point-resolved spectroscopy (PRESS) spectrum (T R = 3 s and T E = 80 ms) acquired from a voxel containing the hippocampus. The C4 proton multiplet resonance of glutamate used for quantification is highlighted.…”

Section: Hormonal Measurementsmentioning

confidence: 99%

“…38,39 In the present study, neurometabolite concentrations in hippocampus of bipolar patients in stable remission on long-term lithium maintenance and of matched controls were investigated in vivo with proton MRS ( 1 H-MRS). Together with the concentrations of NAA, choline-containing compounds and total creatine (tCr), glutamate levels were determined with a previously developed spectroscopy method using point-resolved spectroscopy (PRESS)-based single voxel MRS at 3 T. 40,41 We sought to specifically address the interrelationships between hippocampal glutamate concentrations, other metabolites and activity of the HPA system.…”

Section: Introductionmentioning

confidence: 99%

Glutamate as a spectroscopic marker of hippocampal structural plasticity is elevated in long-term euthymic bipolar patients on chronic lithium therapy and correlates inversely with diurnal cortisol

et al. 2008

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While an excess of glucocorticoids is associated with hippocampal pathology in mood disorders, lithium exerts robust neuroprotective and neurotrophic effects. Here, 21 stably remitted bipolar I patients who had been on chronic lithium maintenance therapy, on average, for more than a decade, and 19 carefully matched healthy controls were studied using 3 T 1 Hmagnetic resonance spectroscopy of left and right hippocampus. Salivary cortisol samples were obtained to assess activity of the hypothalamus-pituitary-adrenal system. Absolute concentrations of N-acetylaspartate (NAA), choline-containing compounds and total creatine were similar in euthymic bipolar patients and healthy controls. Hippocampal glutamate concentrations were significantly increased as an effect of patient status (patients > controls) and laterality (left hippocampus > right hippocampus). Hippocampal glutamate content (Glu) was strongly correlated with NAA. Across groups and within the patient group, diurnal saliva cortisol levels showed a significant inverse relationship with both Glu and NAA. Taken together, these results add to the concept of bipolar disorder as an illness involving disturbed hippocampal structural plasticity under the opposing influences of lithium and glucocorticoids.

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“…In the present study, absolute glutamate concentrations were measured in smokers, former smokers, and never-smokers using single voxel 1H-MRS. The glutamate concentrations were determined with an established method employing a 3-tesla scanner, which has been shown to allow the fair separation of glutamate from glutamine and GABA [12,25] . It was expected that brain regions relevant for executive control over drug-seeking behavior (ACC) and associative learning in relation to pleasurable drug experiences (hippocampus [9] ) would show a dysfunctional glutamatergic neurotrans-…”

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confidence: 99%