Dopaminergic modulation of novelty repetition in Parkinson's disease: A study of P3 event-related brain potentials.

OBJECTIVE: Parkinson's Disease (PD) is a neurodegenerative disease caused by the loss of dopaminergic neurons. Cognitive impairments have been reported using the event-related potential (ERP) technique. Patients show reduced novelty P3 (nP3) amplitudes in oddball experiments, a response to infrequent, surprising stimuli, linked to the orienting response of the brain. The nP3 is thought to depend on dopaminergic neuronal pathways though the effect of dopaminergic medication in PD has not yet been investigated. METHODS: Twenty-two patients with PD were examined "on" and "off" their regular dopaminergic medication in a novelty 3-stimulus-oddball task. Thirty-four healthy controls were also examined over two sessions, but received no medication. P3 amplitudes were compared throughout experimental conditions. RESULTS: All participants showed sizeable novelty difference ERP effects, i.e. ndP3 amplitudes, during both testing sessions. An interaction of diagnosis, medication and testing order was also found, indicating that dopaminergic medication modulated ndP3 in patients with PD across the two testing sessions: We observed enhanced ndP3 amplitudes from PD patients who were off medication on the second testing session. CONCLUSION: Patients with PD 'off' medication showed ERP evidence for repetition-related enhancement of novelty responses. Dopamine depletion in neuronal pathways that are affected by mid-stage PD possibly accounts for this modulation of novelty processing. SIGNIFICANCE: The data in this study potentially suggest that repetition effects on novelty processing in patients with PD are enhanced by dopaminergic depletion.

Changes of auditory stimulus processing in sevoflurane-induced sedation.

Despite the widespread use in clinical practice, little research has been done on mechanisms of sedation. In particular, little is known about the changes in the information processing of external stimuli in sedation. The aim of this study was to investigate the changes of event-related potential (ERP) in auditory passive oddball paradigm when the sedation was induced by sevoflurane inhalation. Electroencephalography (EEG) measurements were obtained for each subject using 32-channel EEG recording devices. Sevoflurane was administered at an initial concentration of 0.8 vol% to induce sedative state. Auditory stimulation based on the passive oddball paradigm was delivered to the subject via an earphone before and after sevoflurane administration. After ERP was extracted from the measured EEG, the topographic distribution of ERP, the temporal changes of ERP in each channel, and the statistical difference in ERP between awake and sedation were analyzed. In the awake state, P300 was observed at 320-360 ms latency, and P300 was concentrated in the frontal and central area. P300 amplitude was significantly decreased in sedation compared to awake. Sevoflurane-induced sedation caused a decrease in P300 amplitude. This result may reflect the weakening of the cognitive function governing attentional process and stimuli discrimination during sedation.

Psilocybin disrupts sensory and higher order cognitive processing but not pre-attentive cognitive processing-study on P300 and mismatch negativity in healthy volunteers.

RATIONALE: Disruption of auditory event-related evoked potentials (ERPs) P300 and mismatch negativity (MMN), electrophysiological markers of attentive and pre-attentive cognitive processing, is repeatedly described in psychosis and schizophrenia. Similar findings were observed in a glutamatergic model of psychosis, but the role of serotonergic 5-HT2A receptors in information processing is less clear. OBJECTIVES: We studied ERPs in a serotonergic model of psychosis, induced by psilocybin, a psychedelic with 5-HT2A/C agonistic properties, in healthy volunteers. METHODS: Twenty subjects (10M/10F) were given 0.26 mg/kg of psilocybin orally in a placebo-controlled, double-blind, cross-over design. ERPs (P300, MMN) were registered during the peak of intoxication. Correlations between measured electrophysiological variables and psilocin serum levels and neuropsychological effects were also analyzed. RESULTS: Psilocybin induced robust psychedelic effects and psychotic-like symptoms, decreased P300 amplitude (p = 0.009) but did not affect the MMN. Psilocybin's disruptive effect on P300 correlated with the intensity of the psychedelic state, which was dependent on the psilocin serum levels. We also observed a decrease in N100 amplitude (p = 0.039) in the P300 paradigm and a negative correlation between P300 and MMN amplitude (p = 0.014). CONCLUSIONS: Even though pre-attentive cognition (MMN) was not affected, processing at the early perceptual level (N100) and in higher-order cognition (P300) was significantly disrupted by psilocybin. Our results have implications for the role of 5-HT2A receptors in altered information processing in psychosis and schizophrenia.

Population Pharmacokinetic/ Pharmacodynamic Modelling of Auditory-Evoked Event-Related Potentials with Lorazepam.

Event-related potentials (ERPs) are commonly used in Neuroscience research, particularly the P3 waveform because it is associated with cognitive brain functions and is easily elicited by auditory or sensory inputs. ERPs are affected by drugs such as lorazepam, which increase the latency and decrease the amplitude of the P3 wave. In this study, auditory-evoked ERPs were generated in 13 older healthy volunteers using an oddball tone paradigm, after administration of single 0.5 and 2 mg doses of lorazepam. Population pharmacokinetics (PK)/pharmacodynamics (PD) models were developed using nonlinear mixed-effects methods in order to assess the effect of lorazepam on the latency and amplitude of the P3 waveforms. The PK/PD models showed that doses of 0.3 mg of lorazepam achieved approximately half of the maximum effect on the latency of the P3 waveform. For P3 amplitude, half the maximum effect was achieved with a dose of 1.2 mg of lorazepam. The PK/PD models also predicted an efficacious dose range of lorazepam, which was close to the recommended therapeutic range. The use of longitudinal P3 latency data allowed better predictions of the lorazepam efficacious dose range than P3 amplitude or aggregate exposure-response data, suggesting that latency could be a more sensitive parameter for drugs with similar mechanisms of action as lorazepam and that time course rather than single time-point ERP data should be collected. Overall, the results suggest that P3 ERP waveforms could be used as potential non-specific biomarkers for functional target engagement for drugs with brain activity, and PK/PD models can aid trial design and choice of doses for development of new drugs with ERP activity.

Auditory processing following infantile spasms: An event-related potential study.

OBJECTIVES: To investigate acoustic auditory processing in patients with recent infantile spasms (IS). METHODS: Patients (n = 22; 12 female; median age 8 months; range 5-11 months) had normal preceding development, brain magnetic resonance imaging (MRI), and neurometabolic testing (West syndrome of unknown cause, uWS). Controls were healthy babies (n = 22; 11 female; median age 6 months; range 3-12 months). Event-related potentials (ERPs) and psychometry (Bayley Scales of Infant Development, Second Edition, BSID-II) took place at a month following IS remission. RESULTS: Following a repeated pure tone, uWS patients showed less suppression of the N100 at the mid-temporal electrodes (p = 0.006), and a prolonged response latency (p = 0.019). Their novelty P300 amplitude over the mid-temporal electrodes was halved (p = 0.001). The peak of the novelty P300 to environmental broadband sounds emerged later over the left temporal lobe in patients (p = 0.015), the lag correlating with duration of spasms (r = 0.547, p = 0.015). BSID-II scores were lower in patients (p < 0.001), with no correlation to ERP. SIGNIFICANCE: Complex acoustic information is processed poorly following IS. This would impair language. Treatment did not reverse this phenomenon, but may have limited its severity. The data are most consistent with altered connectivity of the cortical acoustic processing areas induced by IS.

Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific cognitive parameters in healthy adult volunteers: A placebo controlled study.

INTRODUCTION: Ocimum sanctum (OS), known as Holy basil, has been documented to possess neuroprotective, cognition-enhancing and stress relieving effects in animal models. However there is paucity of clinical studies to document these effects. MATERIALS AND METHODS: Effect of OS on parameters related to cognition and stress in humans was evaluated with administration of 300 milligram capsules of ethanolic leaf extracts of Ocimum sanctum (EtOS) or placebo per day, over 30 days. RESULTS: Intra-group comparison of Sternberg and Stroop test showed improvement in both the placebo and EtOS groups, however, the improvement stabilized after day 15 in the placebo group. Intergroup comparison revealed a significant improvement of the following cognitive parameters in the EtOS as compared to the placebo: reaction time (RT) and error rate (ER) of Sternberg test, RT of neutral task of Stroop, RT and ER of interference task of Stroop. The intra-group comparison of P300 latency, salivary cortisol, and State-Trait Anxiety Inventory showed improvement over time in the EtOS group alone, though the inter-group difference was significant in the P300 latency alone. There were no changes in heart rate (HR), AHR, or galvanic skin response (GSR) or AGSR. CONCLUSION: Ocimum sanctum leaf extract seems to have potential cognition-enhancing properties in humans.

Beta receptor-mediated modulation of the oddball P3 but not error-related ERP components in humans.

RATIONALE: The P3 is a ubiquitous component of stimulus-driven neural activity that can be observed in scalp electrophysiological recordings. Multiple lines of evidence suggest an important role for the noradrenergic system in the generation of the P3. However, pharmacological studies of the P3 using noradrenergic manipulations have so far been limited to agents that affect α2-receptor signaling. OBJECTIVES: The present study investigated whether ß-adrenergic receptors are involved in the generation of the P3 and the error positivity (Pe), a component of the event-related potential that is elicited by errors and that bears many similarities to the P3. METHODS: We used a double-blind, placebo-controlled, crossover design in which we examined in human participants (N = 16) the effect of a single dose of propranolol (80 mg) on the amplitudes of the P3 observed in visual and auditory oddball tasks and the Pe observed in a flanker task. RESULTS: We found that P3s to auditory stimuli were increased in amplitude following treatment with propranolol. Propranolol also modulated the P3 to visual stimuli, but in a direction dependent on participants' level of trait anxiety: In participants with lower trait anxiety, propranolol resulted in a (non-significant) decrease in P3 amplitudes; in participants with higher trait anxiety, propranolol significantly enhanced P3 amplitude. Propranolol did not modulate the amplitude of the Pe or behavioral measures of conflict/error-related performance adjustments. CONCLUSIONS: These results provide the first evidence for involvement of ß-adrenergic receptors in P3 generation. We speculate that propranolol affected the P3 through actions at ß2-receptors in the locus coeruleus.

Low Doses of Long-chain Polyunsaturated Fatty Acids Affect Cognitive Function in Elderly Japanese Men: A Randomized Controlled Trial.

Several studies have reported that the supplementation of long-chain polyunsaturated fatty acids (LCPUFA), such as docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) improve cognitive function in the elderly. However, the doses used in these studies were higher than general dietary LCPUFA intake levels. This randomized, double-blind, placebo-controlled trial evaluated the effects of low doses of LCPUFA supplementation corresponding to general dietary intake on cognitive function in non-demented elderly Japanese participants. Japanese men aged 55-64 years were enrolled and randomly allocated to the placebo or LCPUFA group. Participants received 4 weeks of supplementation with LCPUFA-containing oil (DHA, 300 mg/day; EPA, 100 mg/day; and ARA, 120 mg/day) or purified olive oil as placebo. Event-related potential P300, reflecting cognitive processes, was measured before and after supplementation. A total of 113 participants completed the supplementation period, and the per-protocol analysis included 69 participants. Changes in P300 latency were significantly different between the placebo group (+13.6 msec) and the LCPUFA group (-1.8 msec) after supplementation. Significant increases in DHA (+0.9%) and ARA (+0.6%) contents in plasma phospholipids were observed in the LCPUFA group; no changes were observed in the placebo group. Dietary DHA, EPA, and ARA intake were in the normal range for Japan participants and remained unchanged during the study. These results suggest that low doses of LCPUFA supplementation have the potential to improve cognitive function in elderly Japanese men.

Chinese herbal medicine formula Jieduhuayu granules improves cognitive and neurophysiological functions in patients with cirrhosis who have minimal hepatic encephalopathy: a randomized controlled trial.

BACKGROUND: Minimal hepatic encephalopathy (MHE) impairs patients' cognitive and neurophysiological functions. In this study, we investigated the effect of treatment-related improvement in cognitive and neurophysiological functions. METHODS: We measured psychometric performance by number connection tests part A (NCT-A), digit symbol test (DST), mini-mental state examination (MMSE) and event related potential P300 wave of 80 patients with cirrhosis who have minimal hepatic encephalopathy on inclusion into the study and 15 days later. They were randomly assigned in a 1:1:1:1 ratio to four groups, to receive treatment of Chinese herbal medicine formula (HMG) or lactulose (LG) or Chinese herbal medicine formula combined with lactulose (HMCLG) for 15 days (n=20) or no treatment (CG) (n=20). This study was not blind. RESULTS: The mean number of NCT-A and MMSE scores improved significantly in patients in the HMG (0 day, 102.00±24.49 for NCT-A, 18.55±2.89 for MMSE; 15 days, 78.30±22.55 for NCT-A, 24.20±2.78 for MMSE) compared with patients in the CG after 15 days of follow-up (0 day, 103.00±24.98 for NCT-A, 17.90±2.99 for MMSE; 15 days, 95.65±24.34 for NCT-A, 18.85±3.12 for MMSE), P<0.05; the mean number of P300 latency (ms) and wave amplitude (µV) improved significantly among patients in the HMG after 15 days of treatment (0 day, 341.90±14.04 for latency, 8.40±1.73 for wave amplitude; 15 days, 305.45±23.95 for latency, 13.00±3.80 for wave amplitude) compared with patients in the CG after 15 days of follow-up (0 day, 343.85±14.88 for latency, 8.29±1.77 for wave amplitude; 15 days, 340.40±13.06 for latency, 8.50±1.82 for wave amplitude), P<0.05. Similar improvement were also found among patients in the LG and HMCLG; improvements among patients in the HMG were significantly greater than they were in the LG (P<0.05). Synergistic action were shown among patients in the HMCLG (P<0.05). CONCLUSION: Treatment with Chinese herbal medicine formula Jieduhuayu granules and lactulose may improve cognitive and neurophysiological functions in patients with cirrhosis who have MHE. Compared with lactulose alone, Chinese herbal medicine formula Jieduhuayu granules has higher efficacy of improving cognitive and neurophysiological functions in patients with cirrhosis who have MHE, and the two of them together show synergistic action. TRIAL REGISTRATION NUMBER: ACTRN12614000193673.

Arachidonic acid-enriched triacylglycerol improves cognitive function in elderly with low serum levels of arachidonic acid.

Arachidonic acid (ARA) is an n-6 PUFA and is thought to have an important role in various physiological and psychological functions. Recently, supplementation with ARA-enriched TAG was shown to improve age-related decreases in cognitive function in healthy elderly men. To investigate the influence of baseline serum ARA status on cognitive function and its improvement, we analyzed cognitive function stratified by serum ARA level. The stratified analysis was also conducted for the effects of ARA-enriched TAG supplementation on cognitive improvement. Cognitive function was evaluated by measuring event-related potentials (ERPs), including P300 latency and amplitude. When participants were stratified by baseline serum ARA level, P300 latency was significantly longer and P300 amplitude was generally lower in the low-ARA group than in the high-ARA group. No significant difference in P300 components was observed when participants were stratified by serum levels of any other fatty acid. ARA-enriched TAG supplementation significantly shortened P300 latency and increased P300 amplitude in the low-ARA group, although no significant differences were observed in the high-ARA group. These findings suggest that lower serum ARA levels were associated with cognitive function in elderly men and that ARA-enriched TAG supplementation is more effective in improving cognitive function in healthy elderly men with low serum ARA levels than in those with high serum ARA levels.

Tyrosine ameliorates heat induced delay in event related potential P300 and contingent negative variation.

The efficacy of tyrosine, a catecholamine precursor, as a countermeasure in the reduction of cognitive decline during heat exposure (HE) using event-related potential P300, and contingent negative variation (CNV) was evaluated. Ten healthy males, age 20-30years participated in the study. Volunteers received placebo or tyrosine (6.5g) 90min prior to HE (1.5h in 45°C+30% RH). P300 latency was significantly increased (p<0.01) during exposure with placebo, which was reduced significantly (p<0.01) after tyrosine supplementation. There was an increase in CNV M100 latency (p<0.05) and reaction time (p<0.01) and decrease in M100 amplitude (p<0.01) during HE with placebo, which returns to near normal level with the tyrosine administration. A significantly higher plasma norepinephrine (p<0.05), dopamine and epinephrine levels were detected in tyrosine supplemented group post heat exposure. HE increases the brain catecholamine activity thereby reduces the plasma norepinephrine and dopamine level leading to a reduction in cognitive performances. Tyrosine supplementation increases the catecholamine level and reduces the impairment of cognitive performance during HE.

Family history of psychosis moderates early auditory cortical response abnormalities in non-psychotic bipolar disorder.

OBJECTIVES: Bipolar I disorder is a disabling illness affecting 1% of people worldwide. Family and twin studies suggest that psychotic bipolar disorder (BDP) represents a homogeneous subgroup with an etiology distinct from non-psychotic bipolar disorder (BDNP) and partially shared with schizophrenia. Studies of auditory electrophysiology [e.g., paired-stimulus and oddball measured with electroencephalography (EEG)] consistently report deviations in psychotic groups (schizophrenia, BDP), yet such studies comparing BDP and BDNP are sparse and, in some cases, conflicting. Auditory EEG responses are significantly reduced in unaffected relatives of psychosis patients, suggesting that they may relate to both psychosis liability and expression. METHODS: While 64-sensor EEGs were recorded, age- and gender-matched samples of 70 BDP, 35 BDNP {20 with a family history of psychosis [BDNP(+)]}, and 70 psychiatrically healthy subjects were presented with typical auditory paired-stimuli and auditory oddball paradigms. RESULTS: Oddball P3b reductions were present and indistinguishable across all patient groups. P2s to paired stimuli were abnormal only in BDP and BDNP(+). Conversely, N1 reductions to stimuli in both paradigms and P3a reductions were present in both BDP and BDNP(-) groups but were absent in BDNP(+). CONCLUSIONS: Although nearly all auditory neural response components studied were abnormal in BDP, BDNP abnormalities at early- and mid-latencies were moderated by family psychosis history. The relationship between psychosis expression, heritable psychosis risk, and neurophysiology within bipolar disorder, therefore, may be complex. Consideration of such clinical disease heterogeneity may be important for future investigations of the pathophysiology of major psychiatric disturbance.

Aroma helps to preserve information processing resources of the brain in healthy subjects but not in temporal lobe epilepsy.

PURPOSE: Inhalation of ylang-ylang aroma has been shown to reduce the auditory P300, an event-related potential thought to reflect higher-order processing. Because olfactory function is sometimes disturbed in temporal lobe epilepsy (TLE), the objective of the present study was to determine whether the effect of ylang-ylang aroma on the auditory P300 was impaired in patients with TLE. METHOD: Fourteen subjects with TLE and 14 healthy controls participated in this study. Electroencephalograms were recorded during an auditory oddball task, and ylang-ylang aroma or odorless air was delivered through a mask. RESULTS: We found that the ylang-ylang aroma prolonged the latencies of P300 in both groups. The ylang-ylang aroma significantly reduced the P300 amplitudes of healthy subjects as described previously. However, in TLE patients, the P300 was unaffected by the aroma. CONCLUSION: The current results show that exposure to the ylang-ylang aroma reduced information processing resources in healthy subjects but had limited effects in patients with TLE. We suggest that impaired higher-order olfactory processing in TLE patients may inhibit the effects of the ylang-ylang aroma on the P300.

Cross-diagnostic comparison of duration mismatch negativity and P3a in bipolar disorder and schizophrenia.

OBJECTIVES: Bipolar disorder and schizophrenia share common pathophysiological processes and may have similar perceptual abnormalities. Mismatch negativity (MMN) and P3a - event-related potentials associated with auditory preattentional processing - have been extensively studied in schizophrenia, but rarely in bipolar disorder. Furthermore, MMN and P3a have not been examined between diagnostic subgroups of patients with bipolar disorder. We evaluated MMN and P3a in patients with bipolar disorder compared to patients with schizophrenia and healthy controls. METHODS: MMN and P3a were assessed in 52 bipolar disorder patients, 30 schizophrenia patients, and 27 healthy control subjects during a duration-deviant auditory oddball paradigm. RESULTS: Significant MMN and P3a amplitude reductions were present in patients with bipolar disorder and schizophrenia relative to controls. The MMN reduction was more prominent in patients with schizophrenia than bipolar disorder, at a trend level. P3a did not differ significantly between patient groups. There were no MMN or P3a differences between patients with bipolar I (n = 34) and bipolar II (n = 18) disorder. Patients with bipolar I disorder failed to show lateralized MMN, in contrast to the other groups. No MMN or P3a differences were found between patients with bipolar disorder taking (n = 12) and not taking (n = 40) lithium, as well as between those taking (n = 30) and not taking (n = 22) antipsychotic medications. CONCLUSIONS: Patients with bipolar disorder showed deficits in preattentive auditory processing, including MMN deficits that are less severe and P3a deficits that are slightly more pronounced, than those seen in schizophrenia.

[Event-related potentials in major depressive disorder: the relationship between P300 and treatment response]. / Majör Depresif Bozuklukta Olaya Iliskin Potansiyeller: Tedaviye Yanit ile P300 Arasindaki Iliski.

OBJECTIVE: Although conflicting results have been obtained regarding P300 amplitude and latency in major depressive patients, most studies have reported that major depressive patients have smaller P300 amplitudes and longer latencies than healthy people. This study aimed to investigate the relationship between P300 and treatment response in major depressive disorder patients. METHODS: Twenty-eight patients suffering from major depression who completed 12 weeks of follow-up appointments and 28 healthy people, whose age and gender were matched with patients, were included in the study. Event-related potentials (P300) were recorded for patients before and after treatment with sertraline (50-200 mg/day) for 12 weeks. Treatment response was defined as a 50% or greater decrease in a given patient's total Hamilton Depression Rating Scale score. Pre-treatment and post-treatment P300 amplitude and latency values were compared for responders (n=18), non-responders (n=10) and healthy subjects. RESULTS: No significant difference was found between the P300 amplitude values of responders, non-responders and healthy subjects before or after treatment. Pre-treatment P300 latencies of non-responders were significantly longer than latencies of responders and healthy subjects. After treatment for depression, P300 latency values of responders were normalized, but non-responders still maintained longer P300 latencies than responders and healthy subjects. CONCLUSION: These findings suggest that delayed P300 latency may be related to a non-response to sertraline treatment. No relation was found between P300 amplitude and treatment response.

Multimodal event-related potentials in occupational chronic solvent encephalopathy.

The aim of this study was to test a multimodal event-related potential (ERP) paradigm in chronic solvent encephalopathy (CSE) to develop a sensitive method for the clinical diagnostics to CSE. The study comprised 11 CSE patients and 13 healthy controls. We used three tasks: an auditory odd-ball (AUD), a visual detection (VIS), and a recognition memory (MEM) task. The auditory and visual stimuli were presented in single- and dual-task conditions. The auditory P300 amplitude in single-task condition was smaller in the patient group than in the control group at the parietal (Pz) but not at the frontal midline electrode location. The auditory P300 response in the dual task condition AUD+VIS was unrecognizable in 8 of 11 patients and in 1 of 13 controls and in the AUD+MEM condition in 10 of 11 patients and in 4 of 13 controls. In the AUD+MEM condition, the auditory P300 amplitude at Pz was smaller in the patient group than in the control group. Reaction time for auditory stimuli in both dual conditions as well as for visual stimuli in AUD+VIS condition were in the patient group prolonged. The ERP results indicate that CSE patients present with slowed performance speed and difficulties in allocation of attention. Based on ERP results, the disturbance in brain activity in CSE seems to affect posterior aspects of the frontoparietal continuity. The multimodal paradigm seems promising as a tool for the clinical diagnostics of CSE.

Ketamine effects on brain function--simultaneous fMRI/EEG during a visual oddball task.

BACKGROUND: Behavioral and electrophysiological human ketamine models of schizophrenia are used for testing compounds that target the glutamatergic system. However, corresponding functional neuroimaging models are difficult to reconcile with functional imaging and electrophysiological findings in schizophrenia. Resolving the discrepancies between different observational levels is critical to understand the complex pharmacological ketamine action and its usefulness for modeling schizophrenia pathophysiology. METHODS: We conducted a within-subject, randomized, placebo-controlled pharmacoimaging study in twenty-four male volunteers. Subjects were given low-dose S-ketamine (bolus prior to functional imaging: 0.1mg/kg during 5min, thereafter continuous infusion: 0.015625mg/kg/min reduced by 10% every ten minutes) or placebo while performing a visual oddball task during simultaneous functional magnetic resonance imaging (fMRI) with continuous recording of event-related potentials (P300) and electrodermal activity (EDA). Before and after intervention, psychopathological status was assessed using the Positive and Negative Syndrome Scale (PANSS) and the Altered State of Consciousness (5D-ASC) Rating Scale. RESULTS: P300 amplitude and corresponding BOLD responses were diminished in the ketamine condition in cortical regions being involved in sensory processing/selective attention. In both measurement modalities separation of drug conditions was achieved with area under the curve (AUC) values of up to 0.8-0.9. Ketamine effects were also observed in the clinical, behavioral and peripheral physiological domains (Positive and Negative Syndrome Scale, reaction hit and false alarm rate, electrodermal activity and heart rate) which were in part related to the P300/fMRI measures. CONCLUSION: The findings from our ketamine experiment are consistent across modalities and directly related to observations in schizophrenia supporting the validity of the model. Our investigation provides the first prototypic example of a pharmacoimaging study using simultaneously acquired fMRI/EEG.

Relief of carotid stenosis improves impaired cognition in a rat model of chronic cerebral hypoperfusion.

To investigate how cognitive impairment is affected by the relief of bilateral carotid stenosis, chronic cerebral hypoperfusion was established through stenosis of the bilateral carotid common artery in adult Sprague-Dawley rats. Subsequently, the model rats received the intragastric placebo, donepezil (5 mg per kg), or surgery to relieve carotid stenosis after bilateral carotid common artery stenosis. After carotid stenosis was relieved, the cerebral blood flow values significantly increased, and P300 latency and escape latency in the Morris water-maze were significantly shortened. The concentrations of acetylcholine and norepinephrine in the dorsal hippocampus increased after carotid stenosis was relieved. Furthermore, P300 latency and escape latency were shortened in the relief-treated group compared to the drug-treated group, and acetylcholine levels in the relief-treated group were higher than the drug-treated group. No significant difference was found for the norepinephrine levels in the dorsal hippocampus between the relief-treated and drug-treated groups. Cognitive impairment can be significantly reduced by bilateral carotid stenosis relief, and the effect of relieving stenosis on cognitive dysfunction is superior to the effect of administering an acetylcholinesterase inhibitor.

Association between a cannabinoid receptor gene (CNR1) polymorphism and cannabinoid-induced alterations of the auditory event-related P300 potential.

Numerous studies demonstrated a close relationship between cannabis abuse and schizophrenia with similar impairments in cognitive processing, particularly in P300 generation. Recently, an (AAT)n triplet repeat polymorphism within the cannabinoid receptor gene CNR1 has been found to be associated with both schizophrenia and substance dependence, and to modulate the P300 potential. As previously reported, both acute oral Δ(9)-tetrahydrocannabinol (Δ(9)-THC), the main psychoactive constituent of cannabis, and standardized cannabis extract containing Δ(9)-THC and cannabidiol (CBD) revealed a significant reduction of P300 amplitudes in healthy subjects but did not show any differences among each other. The aim of this study was to investigate whether the (AAT)n polymorphism differentially modulates the effects of Δ(9)-THC and cannabis extract on P300 generation in 20 healthy volunteers during an auditory choice reaction task. For the >10/>10 genotype, there was a significant decrease of P300 amplitude as well as a significant prolongation of P300 latency under pure Δ(9)-THC but not under cannabis extract. Moreover, we found a significant correlation between the number of AAT repeats and P300 variables for the Δ(9)-THC condition. Our data thus indicate that the CNR1 gene seems to be involved in the regulation of the P300 wave as a marker of selective attention and working memory. Moreover, it appears that variations within CNR1 may differentially alter the sensitivity to the acute effects of cannabinoids on P300 generation in healthy subjects.

Pharmacology in health foods: effects of arachidonic acid and docosahexaenoic acid on the age-related decline in brain and cardiovascular system function.

Arachidonic acid (ARA) and docosahexaenoic acid (DHA) are major constituents of cell membranes and play important roles in preserving physiological and psychological function. Recently, data from several studies have indicated that impairments in long-term potentiation (LTP), the process underlying plasticity in synaptic connections, are associated with a decrease in membrane ARA and DHA in aged rats; and treatment of aged rats with either of these polyunsaturated fatty acids (PUFAs) reverses age-related decrease in LTP and the decrease in membrane fatty acid concentration. This review focuses on our recent findings concerning the effects of ARA and DHA on the age-related decline in the function of the brain and cardiovascular system. ARA supplementation decreased P300 latency and increased P300 amplitude of event-related potentials in healthy elderly men. Cognitive impairments in patients with mild cognitive impairment (MCI) and patients with organic brain lesions were significantly improved with ARA and DHA supplementation. ARA and DHA supplementation also increased coronary flow velocity reserve in elderly individuals; this suggests beneficial effects of PUFAs on coronary microcirculation. In conclusion, ARA and DHA may be beneficial in preventing and/or improving age-related declines in brain and cardiovascular system function.