Electroencephalographic activity during direct breastfeeding and breast milk expression in primiparous mothers

Breastfeeding is recognized worldwide as the best option for infant feeding. Expressing breast milk is an alternative for mothers to provide their infants all the benefits of maternal milk. During breast milk expression, mothers receive a distinct kind of sensory stimulation, because there is no direct bodily or affective interaction with their infants, many women report feeling isolated, generating a love-hate relation with pumping, and even low levels of satisfaction while expressing breast milk. While it is well known that the prefrontal, parietal, and temporal cortices play important roles in the emotional and cognitive processing of maternal stimuli, knowledge about how these cortical areas function during breastfeeding is lacking. This study was designed to characterize EEG activity in the prefrontal and parietal cortices and the affective scores of primiparous breastfeeding mothers during two conditions of milk expression: breast milk expression and direct breastfeeding. Participants reported higher valence and arousal and a pleasant state during direct breastfeeding. In the direct breastfeeding condition, both prefrontal areas showed a higher absolute power (AP) of the slow bands, with a lower AP of the alpha band in the parietal cortex. A lower correlation between frontopolar and dorsolateral areas with a higher correlation between prefrontal and parietal cortices was obtained mainly in the right hemisphere. This EEG activity could be linked to an internal state of focused attention and, simultaneously, open monitoring of the environment that suggests an integration of the motive-emotional and cognitive processes necessary for adequate mother-baby interaction during direct breastfeeding.

The role of ketamine in major depressive disorders: Effects on parvalbumin-positive interneurons in hippocampus

Major depressive disorder (MDD) is a complex illness that is arising as a growing public health concern. Although several brain areas are related to this type of disorders, at the cellular level, the parvalbumin-positive cells of the hippocampus interplay a very relevant role. They control pyramidal cell bursts, neuronal networks, basic microcircuit functions, and other complex neuronal tasks involved in mood disorders. In resistant depressions, the efficacy of current antidepressant treatments drops dramatically, so the new rapid-acting antidepressants (RAADs) are being postulated as novel treatments. Ketamine at subanesthetic doses and its derivative metabolites have been proposed as RAADs due to their rapid and sustained action by blocking N-methyl-d-aspartate (NMDA) receptors, which in turn lead to the release of brain-derived neurotrophic factor (BDNF). This mechanism produces a rapid plasticity activation mediated by neurotransmitter homeostasis, synapse recovery, and increased dendritic spines and therefore, it is a promising therapeutic approach to improve cognitive symptoms in MDD.

Streptococcus agalactiae cadD Is Critical for Pathogenesis in the Invertebrate Galleria mellonella Model

Group B Streptococcus (GBS) is a gram-positive bacterium that can cause invasive infections in immunocompromised, elderly, pregnant, or neonatal patients. The invertebrate model, Galleria mellonella, has emerged as an effective tool to study GBS-host interactions; specifically, those conserved within the innate arm of the immune system. We sought to determine the role of metal homeostasis functions in GBS infections of G. mellonella larvae and to validate this model as a tool to study GBS-host interactions. Our results indicate that wild-type GBS infects G. mellonella in a dose-dependent manner, replicates in the invertebrate host, induces larval melanization and larval killing. These results were significantly abrogated in cohorts of larvae infected with the isogenic cadD deletion mutant. Additionally, complementation restored GBS-dependent infection, bacterial burden, larval melanization, and killing to wild-type levels. Together, these results indicate that the G. mellonella model is a useful tool for studying GBS pathogenesis.

Streptococcus agalactiae cadD alleviates metal stress and promotes intracellular survival in macrophages and ascending infection during pregnancy

Perinatal infection with Streptococcus agalactiae, or Group B Streptococcus (GBS), is associated with preterm birth, neonatal sepsis, and stillbirth. Here, we study the interactions of GBS with macrophages, essential sentinel immune cells that defend the gravid reproductive tract. Transcriptional analyses of GBS-macrophage co-cultures reveal enhanced expression of a gene encoding a putative metal resistance determinant, cadD. Deletion of cadD reduces GBS survival in macrophages, metal efflux, and resistance to metal toxicity. In a mouse model of ascending infection during pregnancy, the ΔcadD strain displays attenuated bacterial burden, inflammation, and cytokine production in gestational tissues. Furthermore, depletion of host macrophages alters cytokine expression and decreases GBS invasion in a cadD-dependent fashion. Our results indicate that GBS cadD plays an important role in metal detoxification, which promotes immune evasion and bacterial proliferation in the pregnant host.

The antimicrobial activity of zinc against group B Streptococcus is strain-dependent across diverse sequence types, capsular serotypes, and invasive versus colonizing isolates

BACKGROUND

Streptococcus agalactiae or Group B Streptococcus (GBS) is an encapsulated gram-positive bacterial pathobiont that commonly colonizes the lower gastrointestinal tract and reproductive tract of human hosts. This bacterium can infect the gravid reproductive tract and cause invasive infections of pregnant patients and neonates. Upon colonizing the reproductive tract, the bacterial cell is presented with numerous nutritional challenges imposed by the host. One strategy employed by the host innate immune system is intoxication of bacterial invaders with certain transition metals such as zinc.

METHODOLOGY

Previous work has demonstrated that GBS must employ elegant strategies to circumnavigate zinc stress in order to survive in the vertebrate host. We assessed 30 strains of GBS from diverse isolation sources, capsular serotypes, and sequence types for susceptibility or resistance to zinc intoxication.

RESULTS

Invasive strains, such as those isolated from early onset disease manifestations of GBS infection were significantly less susceptible to zinc toxicity than colonizing strains isolated from rectovaginal swabs of pregnant patients. Additionally, capsular type III (cpsIII) strains and the ST-17 and ST-19 strains exhibited the greatest resilience to zinc stress, whereas ST-1 and ST-12 strains as well as those possessing capsular type Ib (cpsIb) were more sensitive to zinc intoxication. Thus, this study demonstrates that the transition metal zinc possesses antimicrobial properties against a wide range of GBS strains, with isolation source, capsular serotype, and sequence type contributing to susceptibility or resistance to zinc stress.

Antibiofilm Activity of Human Milk Oligosaccharides against Multidrug Resistant and Susceptible Isolates of Acinetobacter baumannii

Acinetobacter baumannii is a serious threat to human health, per the Centers for Disease Control and Prevention's latest threat assessment. A. baumannii is a Gram-negative opportunistic bacterial pathogen that causes severe community and nosocomial infections in immunocompromised patients. Treatment of these infections is confounded by the emergence of multi- and pan-drug resistant strains of A. baumannii. A. baumannii colonizes abiotic and biotic surfaces and evades antimicrobial challenges by forming biofilms, which are three-dimensional architectural structures of cells adhered to a substrate and encased in an extracellular matrix comprised of polymeric substances such as polysaccharides, proteins, and DNA. Biofilm-inhibiting compounds have recently gained attention as a chemotherapeutic strategy to prevent or disperse A. baumannii biofilms and restore the utility of traditional antimicrobial strategies. Recent work indicates that human milk oligosaccharides (HMOs) have potent antibacterial and biofilm-inhibiting properties. We sought to test the utility of HMOs against a bank of clinical isolates of A. baumannii to ascertain changes in bacterial growth or biofilm formation. Our results indicate that out of 18 strains tested, 14 were susceptible to the antibiofilm activities of HMOs, and that the potent antibiofilm activity was observed in strains isolated from diverse anatomical sites, disease manifestations, and across antibiotic-resistant and susceptible strains.

Analysis of Susceptibility to the Antimicrobial and Anti-Biofilm Activity of Human Milk Lactoferrin in Clinical Strains of Streptococcus agalactiae With Diverse Capsular and Sequence Types

Group B Streptococcus (GBS) is one of the leading infection-related causes of adverse maternal and neonatal outcomes. This includes chorioamnionitis, which leads to preterm ruptures of membranes and can ultimately result in preterm or stillbirth. Infection can also lead to maternal and neonatal sepsis that may contribute to mortality. Currently, treatment for GBS infection include a bolus of intrapartum antibiotic prophylaxis to mothers testing positive for GBS colonization during late pregnancy. Lactoferrin is an antimicrobial peptide expressed in human breast milk, mucosal epithelia, and secondary granules of neutrophils. We previously demonstrated that lactoferrin possesses antimicrobial and antibiofilm properties against several strains of GBS. This is largely due to the ability of lactoferrin to bind and sequester iron. We expanded upon that study by assessing the effects of purified human breast milk lactoferrin against a panel of phenotypically and genetically diverse isolates of GBS. Of the 25 GBS isolates screened, lactoferrin reduced bacterial growth in 14 and biofilm formation in 21 strains. Stratifying the data, we observed that colonizing strains were more susceptible to the growth inhibition activity of lactoferrin than invasive isolates at lactoferrin concentrations between 250-750 µg/mL. Treatment with 750 µg/mL of lactoferrin resulted in differences in bacterial growth and biofilm formation between discrete sequence types. Differences in bacterial growth were also observed between capsular serotypes 1a and III. Maternally isolated strains were more susceptible to lactoferrin with respect to bacterial growth, but not biofilm formation, compared to neonatal sepsis isolates. Finally, high biofilm forming GBS strains were more impacted by lactoferrin across all isolates tested. Taken together, this study demonstrates that lactoferrin possesses antimicrobial and antibiofilm properties against a wide range of GBS isolates, with maternally isolated colonizing strains being the most susceptible.

The Innate Immune Glycoprotein Lactoferrin Represses the Helicobacter pylori cag Type IV Secretion System

Chronic infection with Helicobacter pylori increases risk of gastric diseases including gastric cancer. Despite development of a robust immune response, H. pylori persists in the gastric niche. Progression of gastric inflammation to serious disease outcomes is associated with infection with H. pylori strains which encode the cag Type IV Secretion System (cag T4SS). The cag T4SS is responsible for translocating the oncogenic protein CagA into host cells and inducing pro-inflammatory and carcinogenic signaling cascades. Our previous work demonstrated that nutrient iron modulates the activity of the T4SS and biogenesis of T4SS pili. In response to H. pylori infection, the host produces a variety of antimicrobial molecules, including the iron-binding glycoprotein, lactoferrin. Our work shows that apo-lactoferrin exerts antimicrobial activity against H. pylori under iron-limited conditions, while holo-lactoferrin enhances bacterial growth. Culturing H. pylori in the presence of holo-lactoferrin prior to co-culture with gastric epithelial cells, results in repression of the cag T4SS activity. Concomitantly, a decrease in biogenesis of cag T4SS pili at the host-pathogen interface was observed under these culture conditions by high-resolution electron microscopy analyses. Taken together, these results indicate that acquisition of alternate sources of nutrient iron plays a role in regulating the pro-inflammatory activity of a bacterial secretion system and present novel therapeutic targets for the treatment of H. pylori-related disease.

Group B Streptococcus cpsE Is Required for Serotype V Capsule Production and Aids in Biofilm Formation and Ascending Infection of the Reproductive Tract during Pregnancy

Group B Streptococcus (GBS) is an encapsulated Gram-positive pathogen that causes ascending infections of the reproductive tract during pregnancy. The capsule of this organism is a critical virulence factor that has been implicated in a variety of cellular processes to promote pathogenesis. Primarily comprised of carbohydrates, the GBS capsule and its synthesis is driven by the capsule polysaccharide synthesis (cps) operon. The cpsE gene within this operon encodes a putative glycosyltransferase that is responsible for the transfer of a Glc-1-P from UDP-Glc to an undecaprenyl lipid molecule. We hypothesized that the cpsE gene product is important for GBS virulence and ascending infection during pregnancy. Our work demonstrates that a GBS cpsE mutant secretes fewer carbohydrates, has a reduced capsule, and forms less biofilm than the wild-type parental strain. We show that, compared to the parental strain, the ΔcpsE deletion mutant is more readily taken up by human placental macrophages and has a significantly attenuated ability to invade and proliferate in the mouse reproductive tract. Taken together, these results demonstrate that the cpsE gene product is an important virulence factor that aids in GBS colonization and invasion of the gravid reproductive tract.

Analysis of Antimicrobial and Antibiofilm Activity of Human Milk Lactoferrin Compared to Bovine Lactoferrin against Multidrug Resistant and Susceptible Acinetobacter baumannii Clinical Isolates

Acinetobacter baumannii is an opportunistic bacterial pathogen that causes severe infections in immunocompromised patients. The emergence of multi- and pan-drug resistant strains of A. baumannii from clinical sources has confounded treatment and enhanced morbidity and mortality associated with these infections. One way that A. baumannii circumnavigates environmental and antimicrobial challenge is by forming tertiary architectural structures of cells known as biofilms. Biofilm-inhibiting molecules could be deployed as a potential chemotherapeutic strategy to inhibit or disrupt A. baumannii biofilms and mitigate adverse outcomes due to infection. Lactoferrin is an innate immune glycoprotein produced in high concentrations in both human and bovine milk which has previously been shown to have antibacterial and antibiofilm activities. We sought to test lactoferrin against a bank of clinical isolates of A. baumannii to determine changes in bacterial growth or biofilm formation. Our results indicate that human lactoferrin has slightly more potent antibacterial activities than bovine lactoferrin against certain strains of A. baumannii and that these effects are associated with anatomical site of isolation. Additionally, we have shown that both bovine and human lactoferrin can inhibit A. baumannii biofilm formation and that these effects are associated with anatomical site of isolation and whether the strain forms robust or weak biofilms.

Rootstock effects on scion gene expression in maritime pine

Pines are the dominant conifers in Mediterranean forests. As long-lived sessile organisms that seasonally have to cope with drought periods, they have developed a variety of adaptive responses. However, during last decades, highly intense and long-lasting drought events could have contributed to decay and mortality of the most susceptible trees. Among conifer species, Pinus pinaster Ait. shows remarkable ability to adapt to different environments. Previous molecular analysis of a full-sib family designed to study drought response led us to find active transcriptional activity of stress-responding genes even without water deprivation in tolerant genotypes. To improve our knowledge about communication between above- and below-ground organs of maritime pine, we have analyzed four graft-type constructions using two siblings as rootstocks and their progenitors, Gal 1056 and Oria 6, as scions. Transcriptomic profiles of needles from both scions were modified by the rootstock they were grafted on. However, the most significant differential gene expression was observed in drought-sensitive Gal 1056, while in drought-tolerant Oria 6, differential gene expression was very much lower. Furthermore, both scions grafted onto drought-tolerant rootstocks showed activation of genes involved in tolerance to abiotic stress, and is most remarkable in Oria 6 grafts where higher accumulation of transcripts involved in phytohormone action, transcriptional regulation, photosynthesis and signaling has been found. Additionally, processes, such as those related to secondary metabolism, were mainly associated with the scion genotype. This study provides pioneering information about rootstock effects on scion gene expression in conifers.

Antibacterial and Anti-biofilm Activity of the Human Breast Milk Glycoprotein Lactoferrin against Group B Streptococcus

Group B Streptococcus (GBS) is an encapsulated Gram-positive human pathogen that causes invasive infections in pregnant hosts and neonates, as well as immunocompromised individuals. Colonization of the human host requires the ability to adhere to mucosal surfaces and circumnavigate the nutritional challenges and antimicrobial defenses associated with the innate immune response. Biofilm formation is a critical process to facilitate GBS survival and establishment of a replicative niche in the vertebrate host. Previous work has shown that the host responds to GBS infection by producing the innate antimicrobial glycoprotein lactoferrin, which has been implicated in repressing bacterial growth and biofilm formation. Additionally, lactoferrin is highly abundant in human breast milk and could serve a protective role against invasive microbial pathogens. This study demonstrates that human breast milk lactoferrin has antimicrobial and anti-biofilm activity against GBS and inhibits its adherence to human gestational membranes. Together, these results indicate that human milk lactoferrin could be used as a prebiotic chemotherapeutic strategy to limit the impact of bacterial adherence and biofilm formation on GBS-associated disease outcomes.

Analysis of virulence phenotypes and antibiotic resistance in clinical strains of Acinetobacter baumannii isolated in Nashville, Tennessee

BACKGROUND

Acinetobacter baumannii is a gram-negative bacterium which causes opportunistic infections in immunocompromised hosts. Genome plasticity has given rise to a wide range of strain variation with respect to antimicrobial resistance profiles and expression of virulence factors which lead to altered phenotypes associated with pathogenesis. The purpose of this study was to analyze clinical strains of A. baumannii for phenotypic variation that might correlate with virulence phenotypes, antimicrobial resistance patterns, or strain isolation source. We hypothesized that individual strain virulence phenotypes might be associated with anatomical site of isolation or alterations in susceptibility to antimicrobial interventions.

METHODOLOGY

A cohort of 17 clinical isolates of A. baumannii isolated from diverse anatomical sites were evaluated to ascertain phenotypic patterns including biofilm formation, hemolysis, motility, and antimicrobial resistance. Antibiotic susceptibility/resistance to ampicillin-sulbactam, amikacin, ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, cefepime, gentamicin, levofloxacin, meropenem, piperacillin, trimethoprim-sulfamethoxazole, ticarcillin- K clavulanate, tetracyclin, and tobramycin was determined.

RESULTS

Antibiotic resistance was prevalent in many strains including resistance to ampicillin-sulbactam, amikacin, ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, cefepime, gentamicin, levofloxacin, meropenem, piperacillin, trimethoprim-sulfamethoxazole, ticarcillin- K clavulanate, tetracyclin, and tobramycin. All strains tested induced hemolysis on agar plate detection assays. Wound-isolated strains of A. baumannii exhibited higher motility than strains isolated from blood, urine or Foley catheter, or sputum/bronchial wash. A. baumannii strains isolated from patient blood samples formed significantly more biofilm than isolates from wounds, sputum or bronchial wash samples. An inverse relationship between motility and biofilm formation was observed in the cohort of 17 clinical isolates of A. baumannii tested in this study. Motility was also inversely correlated with induction of hemolysis. An inverse correlation was observed between hemolysis and resistance to ticarcillin-k clavulanate, meropenem, and piperacillin. An inverse correlation was also observed between motility and resistance to ampicillin-sulbactam, ceftriaxone, ceftoxamine, ceftazidime, ciprofloxacin, or levofloxacin.

CONCLUSIONS

Strain dependent variations in biofilm and motility are associated with anatomical site of isolation. Biofilm and hemolysis production both have an inverse association with motility in the cohort of strains utilized in this study, and motility and hemolysis were inversely correlated with resistance to numerous antibiotics.

Vitamin D and Streptococci: The Interface of Nutrition, Host Immune Response, and Antimicrobial Activity in Response to Infection

Streptococcus species are common causes of human infection. These Gram-positive, encapsulated bacterial pathogens infect diverse anatomic spaces, leading to infections including skin and soft tissue infection, endocarditis, pneumonia, meningitis, sinusitis, otitis media, chorioamnionitis, sepsis, and even death. Risk for streptococcal infection is highest in low- and middle-income countries where micronutrient deficiency is common. Epidemiological data reveal that vitamin D deficiency is associated with enhanced risk of streptococcal infection and cognate disease outcomes. Additionally, vitamin D improves antibacterial defenses by stimulating innate immune processes such as phagocytosis and enhancing production of reactive oxygen species (oxidative burst) and antimicrobial peptides (including cathelicidin and lactoferrin), which are important for efficient killing of bacteria. This review presents the most recent published work that studies interactions between the micronutrient vitamin D, the host immune system, and pathogenic streptococci as well as comparisons with other relevant infection models.

In vitro fermentation characteristics, in vivo ileal and total tract nutrient digestibilities, and fecal microbiota responses of dogs to α-cyclodextrin

The objectives were to examine in vitro fermentation characteristics, in vivo nutrient digestibility, fecal microbiota, and serum lipid profiles as affected by α-cyclodextrin (ACD) supplementation. Short-chain fatty acid (SCFA) production was measured after in vitro fermentation for 3, 6, 9, and 12 h of ACD, β-cyclodextrin, and γ-cyclodextrin. Five mixed-breed hounds were used in a Latin square design. Each experimental period comprised 14 d, including 10 d for diet adaptation and 4 d for fecal collection. Dogs were fed, twice a day, an extruded diet made with poultry byproduct meal and brewer's rice as the main ingredients. Dogs were supplemented with 0, 1, 2, 3, or 4 g of ACD diluted in 15 mL of water twice daily for a total of 0, 2, 4, 6, and 8 g ACD/d. Maximal in vitro production of total SCFA was lowest for ACD. However, the greatest maximal production of propionate was noted for ACD treatment. Total tract nutrient digestibility and fecal DM concentration linearly decreased ( < 0.05) for treatment groups receiving ACD; no changes were observed for ileal digestibility. Serum cholesterol and triglyceride concentrations were within normal ranges for dogs and were not different among treatments. Similarly, no changes in fecal microbiota were observed. Overall, ACD supplementation appears to have no effect on nutrient absorption in the small intestine but may alter fermentation in the large bowel, which could lead to a higher proportion of propionate production as observed in the in vitro experiment.

Serum lipid profiles, total tract nutrient digestibility, and gastrointestinal tolerance by dogs of α-cyclodextrin

The objectives were to quantify gastrointestinal tolerance, total tract nutrient digestibility, and serum lipid profiles of dogs as affected by α-cyclodextrin (ACD) supplementation and to validate the accuracy of fat analyses techniques using novel ACD-fat complexes. The ACD was hydrolyzed and free sugars and hydrolyzed monosaccharides were quantified using high performance liquid chromatography. Known amount of fats were complexed with ACD, and fat content of complexes were determined using the ether extraction and acid-hydrolyzed fat methods. Nine mixed-breed hounds were used in a crossover design with 3 periods of 10 d each, including 6 d for diet adaptation and 4 d for fecal collection. Dogs were fed twice daily a diet with poultry byproduct meal and brewer's rice as the main ingredients, and chromic oxide (0.2%) was included as a digestion marker. Dogs were supplemented with either 0, 3, or 6 g of ACD diluted in 15 mL of water twice per day for a total of 0, 6, and 12 g ACD per day. The ACD had a very low free sugar concentration and, once hydrolyzed, released only glucose, as expected. Average daily food intake, fecal output (DM basis), and fecal scores were not significantly different among treatments. Body weight and condition score and serum triglycerides and cholesterol concentrations remained unaltered throughout the duration of the experiment. Dry matter, OM, and fat digestibility coefficients were lower (P < 0.05) for both treatment groups compared to the control. The acid-hydrolyzed fat method was valid to measure fat that was bound to ACD. Intake of ACD lowered fat digestibility somewhat but not to the extent previously reported, without affecting serum lipid concentrations or outcomes related to tolerance. Therefore, ACD supplementation resulted in a small decrease in fat digestibility, but ACD supplementation might have potential in modifying serum lipid profiles.

Observing videos of a baby crying or smiling induces similar, but not identical, electroencephalographic responses in biological and adoptive mothers

It is well-known that adoptive mothers respond to cues from their babies in similar ways to biological mothers, and that cortical processing is critical for adequate motive-emotional maternal responses. This study used electroencephalographic activity (EEG) to characterize prefrontal, parietal and temporal functioning in biological mothers (BM), adoptive mothers (AM), and non-mothers (NM), while viewing videos of a baby smiling or crying. The BM presented higher absolute power (AP) in the delta and theta bands (associated with pleasant, positive emotional experiences) in the frontal and parietal areas under all conditions. In response to the smiling video, both types of mothers presented a lower AP in alpha1 in the three cortices (indicative of increased attention) and, mainly in temporal areas, a higher AP in the fast frequencies (beta and gamma, reflecting increased alertness to sensory stimuli and cognitive processing). This EEG pattern in the BM and AM could reflect the greater attention and, probably, the positive mood caused by the smiling video, showing that both are sensitive to these pleasant stimuli. When viewing the video of a baby crying, the AM had higher AP in the fast frequencies (temporal and parietal areas), indicating that they were more reactive to this unpleasant video, while the NM presented only a lower AP in alpha1 in all cortices, a finding that could be associated with the general activation induced by these unpleasant stimuli as a consequence of their lack of maternal experience. These findings should help improve our understanding of the neural mechanisms involved in the processing of sensorial stimuli that establish affective-emotional links during motherhood.

Long-term fish oil supplementation attenuates seizure activity in the amygdala induced by 3-mercaptopropionic acid in adult male rats

Several studies have provided evidence of significant effects of omega-3 fatty acids on brain functionality, including seizures and disorders such as epilepsy. Fish oil (FO) is a marine product rich in unsaturated omega-3 fatty acids. Considering that the amygdala is one of the brain structures most sensitive to seizure generation, we aimed to evaluate the effect of long-term chronic FO supplementation (from embryonic conception to adulthood) on the severity of seizures and amygdaloid electroencephalographic activity (EEG) in a 3-mercaptopropionic acid (3-MPA)-induced seizure model using adult rats. Female Wistar rats were fed a commercial diet supplemented daily with FO (300mg/kg) from puberty through mating, gestation, delivery, and weaning of the pups. Only the male pups were then fed daily with a commercial diet supplemented with the same treatment as the dam up to the age of 150days postpartum, when they were bilaterally implanted in the amygdala to record behavior and EEG activity before, during, and after seizures induced by administering 3-MPA. Results were compared with those obtained from rats supplemented with palm oil (PO) and rats treated with a vehicle (CTRL). The male rats treated with FO showed longer latency to seizure onset, fewer convulsive episodes, and attenuated severity compared those in the PO and CTRL groups according to the Racine scale. Moreover, long-term FO supplementation was associated with a reduction of the absolute power (AP) of the fast frequencies (12-25Hz) in the amygdala during the seizure periods. These findings support the idea that chronic supplementation with omega-3 of marine origin may have antiseizure properties as other studies have suggested.

HANOIPC3: a computer program to evaluate executive functions

This article describes a computer program (HANOIPC3) based on the Tower of Hanoi game that, by analyzing a series of parameters during execution, allows a fast and accurate evaluation of data related to certain executive functions, especially planning, organizing and problem-solving. This computerized version has only one level of difficulty based on the use of 3 disks, but it stipulates an additional rule: only one disk may be moved at a time, and only to an adjacent peg (i.e., no peg can be skipped over). In the original version--without this stipulation--the minimum number of movements required to complete the task is 7, but under the conditions of this computerized version this increases to 26. HANOIPC3 has three important advantages: (1) it allows a researcher or clinician to modify the rules by adding or removing certain conditions, thus augmenting the utility and flexibility in test execution and the interpretation of results; (2) it allows to provide on-line feedback to subjects about their execution; and, (3) it creates a specific file to store the scores that correspond to the parameters obtained during trials. The parameters that can be measured include: latencies (time taken for each movement, measured in seconds), total test time, total number of movements, and the number of correct and incorrect movements. The efficacy and adaptability of this program has been confirmed.

Different functionality of the medial and orbital prefrontal cortex during a sexually motivated task in rats

This study was designed to analyze whether the electroencephalographic (EEG) activity of the medial (mPFC) and orbital prefrontal cortex (oPFC) was modified during the performance of male rats in a T maze under two different conditions, sexually motivated (with previous intromission and females in the goal boxes of the lateral arms) or sexually non-motivated (without previous intromission and with empty goal boxes). Relative power (RP) of three EEG band frequencies, and inter-hemispheric correlation (r) were calculated and a comparison was made between rats under motivated and non-motivated conditions. In the mPFC of sexually motivated males, an increase of the RP in the 6-7 Hz band as well as a decrease in the 8-11 Hz band was observed in relation to an awake-quiet state and during the walk in the maze stem. Similarly, an increase in the r of the 6-7 Hz band was observed during the walk in the maze stem and when remaining near to a receptive female, when compared to non-motivated males. In the oPFC, only the RP of the 6-7 Hz band was increased during the walk in the maze stem of the motivated males. These data suggest that, among sexually motivated males, the mPFC is involved both in anticipatory and motor execution during the performance of the T maze task, whereas the oPFC is only involved in the motor execution of the T maze. These results are in line with other studies suggesting that the mPFC and oPFC are functionally distinct, regions which may work together during certain behaviors and physiological conditions.

Role of corpus callosum in interhemispheric coherent activity during sleep

OBJECTIVE

To investigate to what extent the increase in interhemispheric coherent activity observed from wakefulness to sleep depends on the integrity of the corpus callosum (CC).

METHODS

Interhemispheric coherent activity was analyzed in two epileptic patients selected for callosotomy because of multifocal refractory epilepsy, before and 4 months after callosotomy. One patient underwent complete callosotomy and another was subjected to callosotomy of the anterior 2/3, which offered the possibility of comparing the role of the CC in the coherent activity increase from wakefulness to sleep, between anterior regions with interrupted CC communication (in the two patients) and posterior regions with intact communication (in one of them). Results were compared with a group of normal subjects.

RESULTS

Both patients showed increased coherent activity from wakefulness to sleep after surgery.

CONCLUSIONS

Results demonstrate that interhemispheric coherent activity, despite an attenuation after surgery, is higher during SWS than during wakefulness after sectioning the CC; however, they have to be taken with caution because they come from two patients only.

SIGNIFICANCE

Present results show that the increase in coherent activity during sleep does not depend exclusively on callosal integrity but also on state-dependent influences from sleep-promoting mechanisms, probably spread throughout the thalamo-cortical network.

[Differential effect of left and right temporal lobectomy on emotional recognition and experience in patients with epilepsy]

INTRODUCTION

Temporal lobe and amygdala are structures that participate in emotional processing. The purpose of this study was to determine the differential effect of left (LTL) and right (RTL) temporal lobectomy on emotional recognition and experience as well as mood in treatment resistant epileptics who were evaluated pre and post-surgically.

PATIENTS AND METHODS

Five temporal lobe epileptic patients participated in the study (two from the right and three from the left hemisphere) who were evaluated before and after three months of the surgery. Emotional and prosodic recognition were evaluated, inside and outside of a social context, with and without time limit. Besides, subjective emotional experience while seeing movie fragments was evaluated as well as positive and negative emotional states, anxiety and depression.

RESULTS

After the surgery, patients with RTL had lower number of correct responses in fear facial and prosodic recognition, while patients with LTL did not show deterioration or they even improved. There were not differences as a function of the intervened hemisphere neither in the intensity of emotions perceived in the scenes, nor in the emotional experience, however, both groups experienced a decrease of negative emotions and anxiety.

CONCLUSIONS

The results suggest that RTL had a greater effect on emotional recognition outside of a context and with limited time than LTL, while in the emotional experience there were not differences between groups. Lobectomy induced an improvement on affective states.

Electrical activity of prefrontal cortex and ventral tegmental area during rat maternal behavior

Maternal behavior is a motivated behavior that includes pup-directed sequential motor acts. The dopaminergic (DAergic) brain systems have been proposed to play an important role in voluntary maternal acts, however, not much is known about the way these systems function during the performance of this behavior. The electroencephalogram (EEG) is a sensitive tool that allows determination of the simultaneous functioning of different structures in relation to specific cognitive processes or motor acts. The present study recorded the function of the two structures that constitute the mesoprefrontal DAergic system, ventral tegmental area (VTA) and prefrontal cortex (PFC) by EEG during the performance of various maternal behaviors. Bilateral EEG from the VTA and medial PFC (mPFC) was simultaneously recorded during typical maternal acts and was compared to that recorded during non-maternal behaviors in freely moving female rats. Three different frequency bands (6-7, 8-11, and 12-21 Hz) were obtained from principal component analysis applied to the EEG for both structures. In the left and right mPFC and VTA, absolute power (AP) of the 8-11 Hz band showed a significant increase during pup retrieval compared to the EEG during walking. In the left and right mPFC and VTA, AP of the three bands showed a significant increase during pup licking with respect to forepaw licking. No differences in the EEG were found during inactive nursing behaviors compared to the awake quiet condition. The mPFC and VTA presented characteristic EEG patterns during active maternal behaviors but not during inactive maternal behaviors. This provides electrical evidence of the involvement of these structures in the performance of maternal behavior.

FILDIG: a program to filter brain electrical signals in the frequency domain

A software program to filter brain electrical signals in the frequency domain has been developed and is presently reported. Many other filters are commercially available; however, most of them are linked to data acquisition and/or analysis programs rendering them costly. Depending on the experimental field, the full programs are not always needed. To overcome the need to obtain narrow bands in EEG research and other biological signals in an easy, fast and cheap way, we developed a computer program (FILDIG) that renders an almost ideal in-phase filter in the frequency domain and can be used in all types of personal microcomputers (PC and Mac's) and with few resources. The system uses an interactive graphic display and, with a minimum interface, it is capable of filtering multiple channels and simultaneously obtaining electrical signals (EEG, EMG, EOG, etc.) without noise or specific frequency bands.

Power and coherent oscillations distinguish REM sleep, stage 1 and wakefulness

The objective of this work is to determine differences in spectral power and coherent activity between stage 1 (S1) and REM sleep. The EEG activity of the two sleep stages is almost indistinguishable by visual inspection. Although many efforts have been directed toward understanding the process of falling asleep, little is known about differences in EEG activity between stage 1 (S1) and REM sleep. Polysomnography of 8 healthy young adults from S1, REM sleep and wakefulness was recorded. Spectral power and spectral correlation were obtained for 1-50 Hz. Stage 1 was distinguished (ANOVAs) from REM sleep by lower power in 1-9 Hz, higher power in alpha, beta and gamma, lower interhemispheric correlation in 1-8 Hz and gamma, and higher right correlation in 30-50 Hz. It differed from wakefulness by lower power in 9-50 Hz, but not in 1-8 Hz, or in inter- and intrahemispheric correlation. EEG differences between S1 and REM sleep reside not only in changes in power but also in coherent activity. The different behavior of slow and fast frequencies suggests two different mechanisms involved in the gate into sleep, one implicated in promoting sleep, the thalamo-cortical oscillator mode and the other in reducing alertness involving activation mechanisms. Stage 1 is a mixed state, alertness is already reduced but sleep-promoting mechanisms are not yet fully installed. The EEG differences between these two sleep stages contribute to the understanding of REM sleep and S1 physiology and may be relevant for understanding disorders in falling asleep.

Performance in a test demanding prefrontal functions is favored by early luteal phase progesterone: an electroencephalographic study

There are some psychological studies showing changes in intellectual efficiency before and during menstruation. Many women report that they experience a feeling of difficulty to initiate activities, confront challenging situations and lack of concentration suggesting transient changes in frontal lobe functions related with gonadal hormone levels. Therefore, performance of a task demanding prefrontal functions, the Wisconsin Card Sorting Test, with simultaneous recording of electroencephalographic (EEG) activity was assessed in 9 healthy women, in a repeated measure study, during ovulation (OVU), early luteal (EL), late luteal (LL) and menstrual (MEN) phases. Spectral power of base line and task EEG, and number of responses to reach successful and unsuccessful outcomes in the task were evaluated. Performance was impaired to a certain degree during the OVU phase and was associated with an attenuated alpha1 power and with an increase of the theta and beta2 power. Performance was better during EL phase, when progesterone level is at its highest, no significant changes were observed from BL to task. Performance was worse during LL phase when hormone levels are at its lowest and was associated with a decrease in beta1 and beta2 power together with a significant attenuation of alpha1 and alpha2 power. During MEN phase performance was also improved and was associated with a significant decrease of alpha1 and alpha2 power and no changes in beta power were observed. These findings show that performance of a task demanding internal attention and planning is modulated by physiological progesterone and estrogen levels during menstrual cycle and is associated with specific EEG profiles.

POTENCOR: a program to calculate power and correlation spectra of EEG signals

This work describes a computer program (POTENCOR) that applying the Fast Fourier Transform and Pearson product-moment correlation, can calculate easily, fast and accurately the absolute and relative power as well as the inter- and intrahemispheric correlation between every pair of EEG signals for narrow bands and for broad bands. POTENCOR has three main advantages: (1) it allows calculation of inter- and intrahemispheric correlation spectra, for which to our knowledge, there is no commercial program available; (2) the absolute and relative power values are not affected by the number of points that constitutes the signal segment; and (3) in case of making the analysis by each segment the temporal evolution for each EEG parameter can be graphically represented. The utility and flexibility of this program has been confirmed in many clinical and experimental researches.

[Olanzapine effects on emotional recognition in treatment refractory schizophrenics]

INTRODUCTION

The main purpose of this study was to determine if olanzapine (OLZ) can improve the ability to recognize emotional expressions, in the facial, prosodic and contextual modalities in treatment refractory schizophrenics (TRS) and, if this could be related to its effects on depressive symptoms.

METHOD

14 TRS participated in the study. The Calgary Depression Scale and tasks for recognition of facial, prosodic and contextual emotions were applied prior to and 8 weeks after consuming OLZ. The results were compared to a control group (CO).

RESULTS

TRS obtained lower scores than the CO on the recognition of facial and prosodic emotions. They also showed less empathy to the happiness film and they expressed incongruous answers on the contextual emotions. The TRS increased the number of correct responses for the prosodic recognition of happiness and they showed a reduction in their depressive symptomatology after OLZ treatment.

CONCLUSIONS

OLZ caused a decrease of the depressive symptoms and improved the interpretation of positive prosodic affective stimuli, an aspect that may facilitate the social adaptation of TRS.

Rapid eye movement sleep dreaming is characterized by uncoupled EEG activity between frontal and perceptual cortical regions

EEG coherent activity is involved in the binding of spatially separated but temporally correlated stimuli into whole events. Cognitive features of rapid eye movement sleep (REM) dreaming resemble frontal lobe dysfunction. Therefore, temporal coupling of EEG activity between frontal and perceptual regions was analyzed from 10 min prior to dream reports (8 adults) from stage-2 and REM sleep. EEG correlation between frontal and perceptual regions decreased and, among perceptual regions increased during REM. The temporal dissociation of EEG activity between executive and perceptual regions supplies an inadequate mechanism for the binding and interpretation of ongoing perceptual activity resulting in dream bizarreness.

[Impairments in attention and facial emotion recognition in treatment of refractory and non refractory schizophrenics evaluated through an odd-ball paradigm]

INTRODUCTION

Some of the processes impaired in schizophrenia are attention and emotional recognition. The aim of this study was to test: 1) if refractory schizophrenics (RS) present higher attentional deficits than non refractory (NR) evaluated through performance and the P300 amplitude in an odd ball paradigm using letters as stimuli; 2) if emotional recognition deficits in schizophrenics can be reflected by means of a similar paradigm than that used for letters, especially in RS, and; 3) if there exist a correlation between P300 amplitude and the level of psychopathology in these patients.

PATIENTS AND METHODS

Performance and P300 amplitude were measured during a letter (LE) task and a similar one of facial emotion recognition (ER) applicating an odd ball paradigm, on 10 normal controls (CO), 10 NR and 10 RS.

RESULTS

Reaction time was longer in both tasks and in LE, P300 amplitude was lower in NR and RS than in CO. In ER the RS showed a lower number of correct responses and higher of omissions than NR and CO, correlated with neuroleptics doses. A negative correlation between P300 amplitude and the scores of BPRS and PANSS positive symptoms scale was only found for the NR in ER.

CONCLUSIONS

Present results point out that RS show similar deficits in relation to attention as NR do, but they show major deficits in emotional recognition related with neuroleptics doses. Furthermore, a lower P300 amplitude for NR was related to a higher level of psychopathology only in EF.

Abnormal EEG patterns in treatment-resistant schizophrenic patients

This study was conducted in order to compare the EEG patterns of schizophrenics who do not respond to typical neuroleptics with those who do respond under typical neuroleptic medication and a group of controls. Absolute (AP) and relative power (RP), and inter- and intrahemispheric correlations were calculated. Nonresistant schizophrenics showed lower delta RP, higher alpha 1 AP and RP and higher correlation between prefrontal areas than the resistant ones and controls. Resistant schizophrenics showed lower alpha 2 RP, lower beta 1 and beta 2 in temporal but higher beta 2 AP and RP in occipital derivations, and higher intrahemispheric correlation between Fp2 and F4 and lower between F8 and T4 than the nonresistant and controls. The resistants also showed a higher antero-posterior beta 1 and beta 2 index than the controls. We concluded that the EEG pattern showed by the nonresistants may be associated with their good neuroleptic response that was not present in the resistant schizophrenics.

EEG bands during wakefulness, slow-wave, and paradoxical sleep as a result of principal component analysis in the rat

Rat EEG has been empirically divided in bands that frequently do not correspond with EEG generators nor with the functional meaning of EEG rhythms. Power spectra from wakefulness (W), slow-wave sleep (SWS), and paradoxical sleep (PS) of Wistar rats were submitted to Principal Component Analyses (PCA) to investigate which frequencies are covariant. Three independent eigenvectors were identified for SWS: a band between 1-6, an intermediate band between 7-15, and a fast band between 16-32 Hz (90.74% of the variance); two independent eigenvectors were extracted for PS: slow frequencies between 1-6 covarying together with frequencies between 11-16 Hz, and activity between 6-10 covarying together with fast frequencies between 17-32 Hz (80.38% of the variance); four eigen-vectors were obtained for W: 3-7, 8-9, 10-21 and 21-32 Hz (81.47% of the variance). Vigilance states showed significant differences in AP from 1 to 22 Hz. PCA extracted broad bands different for each vigilance state, which included the most representative EEG activities characteristic of them. These results indicate that during SWS, slow oscillations include frequencies up to 6 Hz, and spindle oscillations frequencies down to 7 Hz. No alpha frequencies were identified as an independent band. Frequencies within theta and beta were gathered in the same eigenvector during PS and in different eigenvectors during W suggesting coordinated activation of hippocampal and cortical systems during PS. These bands are consistent with the underlying neurophysiological mechanisms of sleep and wakefulness and with firing frequencies of generators of rhythmic activity obtained in cellular studies in animals.

A new rabbit species (Sylvilagus, Mammalia: Leporidae) from the lowlands of Venezuela

A new species of Venezuelan rabbit of the genus Sylvilagus from Fundo Millano (08 degrees 46'N and 69 degrees 56'W) and Chorrosco Bajo (08 degrees 05'N and 69 degrees 18'W), between 190 and 120 masl, state of Barinas, is described based on: 1. Body and skull measurements. 2. Coloration patterns of the pelage. 3. Arrangement and length of the color hair bands of dorsal, lateral, ventral nuchal, and gular patches. Body and cranial measurements, and some color patterns of the new species, Sylvilagus varynaensis, were compared with those of the closest relative groups such as S. brasiliensis (from Venezuela and Brazil), S. b. meridensis from the Venezuelan paramos, and three of the most representative groups of S. floridanus (S. f. continentis, S. f. orinoci, and S. f. valenciae). Most of the values recorded for these parameters were significantly higher for the new species (P < 0.005; Student "t" test). Cluster and principal components analysis of the data recorded for cranial characteristics indicated that S. varynaensis is the largest and darkest of the known Venezuelan rabbits, with a broader elongated skull and a different arrangement of the color hair bands.

Paradoxical sleep is characterized by uncoupled gamma activity between frontal and perceptual cortical regions

STUDY OBJECTIVES

Coherent activity of fast activity has been postulated to be a common language of the brain involved in the processing of information and in integration of spatially separated but temporally correlated stimuli into whole events. Any disruption affecting temporality would result in distortion of cognitive activity. Dreaming during paradoxical sleep (PS) shows cognitive alterations that mimic frontal lobe dysfunction. Decreased temporal coupling of EEG between frontal and perceptual regions was hypothesized. The main objective was to explore temporal relationships of fast activity among these regions.

DESIGN

N/A.

SETTING

N/A.

PARTICIPANTS

8 young adults.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Interhemispheric (INTERr) and intrahemispheric (INTRAr) EEG correlation spectra (1-50 Hz) were obtained for wakefulness, stage 2, stage 4, and PS during the second night spent at the laboratory. INTERr showed a significant overall increase during sleep in comparison to wakefulness, whereas INTRAr of fast activity (27-48 Hz) between frontal-perceptual regions (F-P, F-O, F-T, Fp-P, Fp-T) decreased exclusively during PS while INTRAr among perceptual regions (P-O, P-T, O-T) maintained wakefulness values.

CONCLUSIONS

Present results demonstrate state- and frequency-dependent shifts on temporal coupling. The hypothesized decrease in correlation of fast activity between frontal and perceptual regions during PS was confirmed. This decrease of temporal coupling might underlie the loss of voluntary direction of thinking and congruence with social and temporal context and the lack of judgment and passive acceptance of bizarreness during PS dreaming. The wakefulness levels in correlation of fast activity among perceptual regions might explain perceptual acuity during PS dreaming.

EEG bands during wakefulness, slow-wave and paradoxical sleep as a result of principal component analysis in man

Human electroencephalogram (EEG) has been divided in bands established by visual inspection that frequently do not correspond with EEG generators nor with functional meaning of EEG rhythms. Power spectra from wakefulness, stage 2, stage 4 and paradoxical sleep of 8 young adults were submitted to Principal Component Analyses to investigate which frequencies covaried together. Two identical eigenvectors were identified for stage 2 and stage 4: 1 to 8 Hz and 5 to 15 Hz (87.95 and 84.62 % of the total variance respectively). Two eigenvectors were extracted for PS: 1 to 9 Hz and 10 to 15 Hz (81.62% of the total variance). Three eigenvectors were obtained for W: with frequencies between 1 to 7 Hz, 7 to 11 Hz, and 12 to 15 Hz (78.32% of the total variance). Power for all frequencies showed significant differences among vigilance states. These results indicate that slow wave activity can oscillate at higher frequencies, up to 8 Hz, and that spindle oscillations have a wider range down to 5 Hz. No theta band was independently identified, suggesting either that delta and theta oscillations are two rhythms under the same global influence, or that the traditional division of theta band in the human cortical EEG is artificial. Alpha as a band was identified only during wakefulness. Principal component analysis upon spectral densities extracted broad bands different for each vigilance state and from traditional bands, consistent with functional significance of EEG and with frequencies of generators of rhythmic activity obtained in cellular studies in animals.

Heterologous expression of a plant small heat-shock protein enhances Escherichia coli viability under heat and cold stress

A small heat-shock protein (sHSP) that shows molecular chaperone activity in vitro was recently purified from mature chestnut (Castanea sativa) cotyledons. This protein, renamed here as CsHSP17. 5, belongs to cytosolic class I, as revealed by cDNA sequencing and immunoelectron microscopy. Recombinant CsHSP17.5 was overexpressed in Escherichia coli to study its possible function under stress conditions. Upon transfer from 37 degrees C to 50 degrees C, a temperature known to cause cell autolysis, those cells that accumulated CsHSP17.5 showed improved viability compared with control cultures. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of cell lysates suggested that such a protective effect in vivo is due to the ability of recombinant sHSP to maintain soluble cytosolic proteins in their native conformation, with little substrate specificity. To test the recent hypothesis that sHSPs may be involved in protection against cold stress, we also studied the viability of recombinant cells at 4 degrees C. Unlike the major heat-induced chaperone, GroEL/ES, the chestnut sHSP significantly enhanced cell survivability at this temperature. CsHSP17.5 thus represents an example of a HSP capable of protecting cells against both thermal extremes. Consistent with these findings, high-level induction of homologous transcripts was observed in vegetative tissues of chestnut plantlets exposed to either type of thermal stress but not salt stress.

Amplitude reduction in visual event-related potentials as a function of sleep deprivation

Eight adult males were subjected to 40 hours of total sleep deprivation (TSD). Reaction time in a visual task and electroncephalographam (C3) were evaluated every 2 hours. One second of EEG before the stimuli was Fourier-transformed, and 750 ms after target and nontarget stimuli were averaged and visual event-related potentials (ERP) were obtained. Factorial analysis identified time windows that showed significant amplitude reduction and longer latencies with TSD: (1) 140 to 288 ms (P180-N242-P281); (2) 288 to 413 ms and 601 to 749 ms (N382; P718) and; (3) 531 to 601 ms (N500). Effect was strongest for N382 and P718, the amplitudes of which dropped to 20% of original size. The entire waveform recovered initial amplitudes and latencies after recovery sleep except for P718 latency. Waveforms within similar time intervals have been associated with attentional gating, sensory discrimination, target selection, uncertainty and decision processes. Amplitudes of the visual ERP were inversely correlated with hours of TSD, reaction time, and absolute power of the prestimulus EEG. Present results clearly show changes in fundamental neurophysiologic mechanisms as a result of TSD, indicating variability and reduction of the alertness mechanisms and changes in thalamocortical gating affecting attention, discrimination and decision-making.

Effect of diazepam and sex hormones on EEG of gonadectomized male and female rats

Waking EEG was recorded from left and right parietals in 60 adult Wistar rats gonadectomized after puberty during 5 days, 1 as baseline, 1 with vehicle and 1 with 10 mg/kg i.m. of diazepam with hormonal treatment (either testosterone propionate, 5-alpha-dihydrotestosterone or vehicle in males and progesterone, estradiol benzoate or vehicle in females). Quantitative EEG analysis showed that: diazepam in gonadectomized males increased absolute power of alpha, beta 1 and beta 2, increased interparietal correlation of delta and decreased interparietal correlation of slow theta, fast theta and beta 1, whereas in gonadectomized females, diazepam additionally decreased slow and fast theta absolute power. EEG effects were not modified by testosterone propionate or 5-alpha-dihydrotestosterone treatment in males. Diazepam plus estradiol rendered the female EEG response similar to the gonadectomized or testosterone-treated males response; diazepam plus progesterone induced the same response in females as in gonadectomized females and additionally induced interparietal asymmetry and decreased interparietal correlation of all EEG bands. Present results and information on the effects of diazepam on interparietal coupling of EEG and demonstrate that the EEG response to diazepam in adult rats is sexually dimorphic and depends on sex as well as on activational effects of gonadal steroids.

Characteristic frequency bands of the cortico-frontal EEG during the sexual interaction of the male rat as a result of factorial analysis

The electrocorticogram (ECoG) from the prefrontal cortex was simultaneously recorded with the accelerometric signals of pelvic thrusting performed by male rats during sexual behavior. The changes in the prefrontal ECoG were precisely correlated in time with well defined elements of male rat copulation. Principal component analysis allowed to identify three distinct bands of frequencies in the frontal ECoG: the absolute power (AP) of the 4-16 Hz band was increased in the 500-ms periods before, during, and after the execution of pelvic thrusting in mount, intromission and ejaculation responses; the AP of the 18-24 Hz band was selectively increased during the execution of pelvic thrusting at the three copulatory responses, whereas the AP of the 26-32 Hz band was increased only during the pelvic moments of mount and intromission responses. These results show that the electroencephalographic activity of the prefrontal cortex of the male rat is related to the performance of sexual behavior, supporting the concept that this cortical area is involved in the organization of sequential behaviors, as sexual behavior.

Computer programs to analyze brain electrical activity during copulatory pelvic thrusting in male rats

Two microcomputer programs have been developed to simultaneously record and analyze the brain electrical activity: multiple unit activity (MUA) and electroencephalogram (EEG), and the accelerometric signals generated in relation to the pelvic thrusting that performs the male rat during the copulatory responses of mount, intromission, and ejaculation. CAPTUMUL is a program allowing the on line capture of the different signals and the further off line delimitation of the brain signals occurring in exact temporal relation with the accelerometric record of motor responses. The ANAMUA program allows the off line analysis of the neuronal firing rate in MUA records at different discrimination levels according to the amplitude of the neuronal spikes, and compare these data in various behavioral situations. The use of these programs provides a way of correlating in time the changes of brain electrical activity occurring in animals in free-movement with the brief motor events of copulation as well as with other behaviors (i.e., genital grooming, sniffing, running, walking). Advantages of this software include the recording of sequential events, a better and rapid handling of data and a reliable method to analyze the MUA with different discrimination levels according to the amplitude of the neuronal spikes.

Stability of EEG inter- and intrahemispheric correlation in women

EEG correlation and coherence analyses have been used to study functional relationships between cortical regions, and found to vary as a function of physiological conditions, sex hormones and cognitive processes. However, the utility of serial EEG studies is dependent upon the within-subject reliability of repeated EEG recordings. The present study was undertaken to assess the within-subject and within-group stability of EEG correlations in a group of young women (n = 9). EEG was recorded during relaxed wakefulness at F3, F4, C3, C4, P3, P4, O1 and O2 for 11 sessions, during 1 month. Ten artifact free 2-s epochs of EEG from each session were digitally filtered by means of a fast Fourier transform into 6 broad bands, and correlation coefficients between the EEG activity of every pair of derivations and bands were calculated in the time domain. All EEG features were submitted to principal component analysis and the first 5 components did not show significant differences between sessions (ANOVAs) for any band or pair of derivations. Alpha and beta showed higher variability whereas slow bands showed very little variability. The within-subject stability was assessed calculating multiple correlation coefficients between all EEG features of the eleven sessions of each subject: R-values ranged from 0.85 to 0.97. Present results indicate that the pattern of functional relationships between cortical regions during resting wakefulness is a stable characteristic for each woman at least over a 1 month period and that there are no significant group differences over sessions when menstrual phases are randomly distributed between women.

Subcortical multiple unit activity changes during rat male sexual behavior

Multiple unit activity (MUA) was recorded from the ventral tegmental area (VTA) and mesencephalic locomotor region (MLR) during copulatory behavior of freely moving male rats. Simultaneous accelerometric recordings of the copulatory pelvic thrusting performed by the male rat were taken to precisely correlate in time the changes in MUA with well defined elements of copulation. The baseline MUA firing rates recorded in the quiet-alert condition in the VTA and in the MLR were significantly increased during pursuit of the female by the male; significantly higher MUA firing rates were found in the VTA at the 500 ms periods before and during the execution of pelvic thrusting in mount, intromission, and ejaculation responses as compared to the baseline, and returned to this value when these responses ended. The maximum MUA firing rate in the MLR was obtained during the execution of pelvic thrusting in each copulatory response, and it remained significantly elevated, as compared to the baseline, after thrusting and at the postintromission and postejaculatory genital grooming, then decreasing to basal values at the initial part of the postejaculatory interval. The fact that the highest changes in MUA were related to pelvic thrusting suggests a major participation of both structures in the execution of motor copulatory responses.

Effect of spatial ability and sex on inter- and intrahemispheric correlation of EEG activity

Inter- and intrahemispheric correlation of the EEG activity at rest was computed in two groups of men and women, between 17 and 21 years old, with extreme degrees of spatial ability (SA) evaluated by the Spatial Relations Subtest of the Differential Aptitudes Test (DAT). Interhemispheric (INTERr) and intrahemispheric (INTRAr) EEG correlations were computed by means of Pearson product-moment coefficients for 5 EEG bands after digitally filtering with an FFT. Women showed significantly higher INTERr of alpha 1 between left and right centrals, lower INTRAr between right frontal and right central regions and lower INTRAr within the left than in the right hemisphere. High SA subjects showed lower INTERr between left and right frontal derivations and higher INTRAr between frontal and parietal and between central and parietal regions of both hemispheres. Sex interacted with SA in INTRAr of alpha between right frontal and right temporal regions with high SA women showing lower INTRAr than low SA women and than men. The present results indicate a different inter- and intrahemispheric functional organization in men and women and in subjects with high and low spatial ability.

EEG coherence or EEG correlation?

In view of the widespread use of electroencephalographic correlation (r) and coherence (Coh) analyses in studying brain functional relationships, it seems important to illustrate results yielded by both methods. Although they are considered as equivalent, they show important differences. Results obtained from r and Coh were compared using: (a) 2 Hz sinusoidal signals, where phase and amplitude were artificially manipulated and, (b) Coh and r spectra obtained between each pair of derivations (C3, C4, F3, F4, T3 and T4) from wakefulness, stage 2, stage 4 and paradoxical sleep (n = 8). The following results were obtained: significant Pearson product-moment coefficients were obtained between r and Coh spectra in the range of 0.86 to 0.96 for interhemispheric and 0.60 to 0.90, for intrahemispheric paris; as a result of principal component analyses, the same three frequency bands were formed for r and Coh spectra with the exception of one single bin; similar results for r and Coh were obtained by two-way ANOVAs (physiological stages by derivations). In conclusion, as expected, a high degree of comparability between r and Coh was observed under normal physiological conditions and with the use of good quality recordings.

Time course of reaction time and EEG while performing a vigilance task during total sleep deprivation

Nine young adult male (23-30 years old) paid volunteers were subjected to total sleep deprivation (TSD), after two consecutive nights in the laboratory, for 40 hours (from 0800 hours on the first day to 2400 hours on the following day). Oral temperature (OT), reaction time (RT) in a visual vigilance task, and electroencephalogram (EEG; C3, C4, T3, and T4) while performing the task were recorded every 2 hours during TSD and after recovery sleep. One second of EEG, before target and non-target stimuli for every subject and condition was visually inspected, and artifact-free epochs were Fourier transformed. Absolute power (AP) was calculated for 4-20 Hz (full band) and for theta, alpha 1, alpha 2, and beta 1. Analyses of variance (ANOVAs), with TSD and time-of-day as factors, showed the following significant results. TSD induced an increase in RT and AP of the full band at C3 and C4, of all bands at C3, of theta at T3, and of beta 1 at T4 (p < 0.009 for all comparisons). No time-of-day effects nor interactions were found. OT was not affected by TSD. All variables returned to baseline values after recovery sleep. RT and EEG power showed a linear increase with accumulating hours of wakefulness. The increment in RT also correlated with the increase in EEG power. The results demonstrate that the increment in RT is associated with the increase in AP, particularly in the left central cortex; that the EEG may be used to identify sleepiness; and that EEG during task performance is more sensitive to TSD than during relaxed wakefulness.

Inter and intrahemispheric EEG correlation as a function of sleep cycles

1. Inter (INTERr) and intrahemispheric (INTRAr) EEG correlation were assessed in 8 young male adults during wakefulness (W) with eyes closed before going to sleep, and during stage 2 (S2), stage 4 (S4) and paradoxical sleep (PS) of the first three sleep cycles during the second night spent at the laboratory. 2. Pearson product-moment correlation were calculated between EEG signals of each pair of electrodes (C3, C4, F3, F4, T3, T4) for every 0.5 Hz from 1.5 to 15 Hz. 3. INTERr and INTRAr of 1.5-6.5 and 11-15 Hz were significantly higher during stage 2 and 4; INTERr of 1.5-6.5 Hz was also higher during PS in cycle 1 and 2, whereas INTERr and INTRAr of 7-10.5 Hz were lower than during wakefulness. 4. INTRAr of S2 and S4 approximated, whereas INTRAr oF PS moved away from W over successive sleep cycles. 5. These data show that cortical changes during sleep are also observed in functional differentiation between cortical sites. Inter and intrahemispheric differentiation is attenuated during stage 2 and 4 while during PS only interhemispheric differentiation is attenuated but intrahemispheric differentiation is accentuated compared to wakefulness. This pattern of cortical differentiation may be of relevance for the understanding of mental activity changes during sleep.

Effect of total sleep deprivation on reaction time and waking EEG activity in man

Nine paid volunteers were sleep deprived over a period of 40 hours. Every 2 hours during total sleep deprivation (TSD) and after recovery sleep, oral temperature (OT), reaction time (RT) in a vigilance task and electroencephalogram (EEG) with eyes open and closed (C3, C4, T3 and T4) were recorded. Ten artifact-free samples from each condition were Fourier transformed. Absolute power was calculated for six bands. Analyses of variance with deprivation and time of day as factors showed the following significant results: 1) TSD induced an increase in RT, of theta power in all derivations, of beta power in both centrals and a decrease of alpha power with eyes closed; OT was not affected. 2) All bands showed a peak of power at 1800 hours, 2 hours in advance of the OT acrophase at 2000 hours. All variables recovered baseline values after 1 night of sleep. Significant linear correlations of hours of wakefulness with EEG and RT, and of EEG power with OT and RT, were observed. The present findings show a linear increase in EEG power and RT with TSD, and a diurnal oscillation of EEG power, which is independent of TSD.

Effect of spatial ability and sex on EEG power in high school students

Performance at eight cognitive tests and EEG spectral power at rest was computed in 2 groups of men and women, between 17 and 21 years of age, with extreme degrees of spatial ability (SA) evaluated by the spatial relations subtest of the DAT: a low spatial ability group (10 men, 10 women) with scores below percentile 30 and a high spatial ability group (10 men, 10 women) with scores above percentile 80. Ten EEG artifact free samples, 4.096 sec each, were analyzed and absolute (AP) and relative power (RP) were obtained for 5 frequency bands using an FFT. EEG was submitted to principal component analysis and two way ANOVAs. High SA showed lower AP in the entire spectrum with eyes open and closed, and lower alpha 1 RP with eyes open than low SA group regardless of sex. The difference between low and high SA was better explained by high alpha AP at all derivations and high theta AP at right derivations and at left central and occipital regions. Women showed higher beta 1 and beta 2 AP at all derivations except at temporal regions than men regardless of SA scores.