Replacing fishmeal with plant protein in Atlantic salmon (Salmo salar) diets by supplementation with fish protein hydrolysate.

The effects of feeding an 80% plant protein diet, with and without fish protein hydrolysate (FPH) supplementation, on the growth and gut health of Atlantic salmon were investigated. Fish were fed either (A) a control diet containing 35% fishmeal, (B) an 80% plant protein diet with 15% fishmeal, (C) an 80% plant protein diet with 5% fishmeal and 10% partly hydrolysed protein, or (D) an 80% plant protein diet with 5% fishmeal and 10% soluble protein hydrolysate. Fish on the 80% plant- 15% fishmeal diet were significantly smaller than fish in the other dietary groups. However, partly-hydrolysed protein supplementation allowed fish to grow as well as fish fed the control 35% fishmeal diet. Fish fed the FPH diets (diets C and D) had significantly higher levels of amino acids in their blood, including 48% and 27% more branched chain amino acids compared to fish on the 35% fishmeal diet, respectively. Plant protein significantly altered gut microbial composition, significantly decreasing α-diversity. Spirochaetes and the families Moritellaceae, Psychromonadaceae, Helicobacteraceae and Bacteroidaceae were all found at significantly lower abundances in the groups fed 80% plant protein diets compared to the control fishmeal diet.

T lymphocytes possess the machinery for 5-HT synthesis, storage, degradation and release.

AIM: Although activated T lymphocytes express tryptophan hydroxylase 1 and produce 5-HT, the metabolic fate and cellular handling of this 5-HT is unclear. Here, we investigated key proteins in T cells linked to 5-HT metabolism and storage and compare differences in 5-HT synthesis and metabolism between T-cell subsets. METHODS: We cultured human Jurkat T cells and mouse splenic CD3(+) , CD4(+) and CD8(+) T cells with or without T-cell activators (phorbol ester/ionomycin, concavalin A or plate-bound anti-CD3 antibody). Subsequently, we measured mRNA and/or protein for monoamine oxidase A and B, vesicular monoamine transporter 1 and 2, N-acetyl transferase and tryptophan hydroxylase 1. In addition, we measured the release of exogenously loaded [(3) H]5-HT and endogenously synthesized 5-HT from CD4(+) and CD8(+) T-cell subsets. RESULTS: Human and mouse T cells selectively express monoamine oxidase A. Following T-cell activation, mRNA levels of MAO-A increase robustly in parallel with tryptophan hydroxylase 1. Concomitant with these changes, T cells increase the expression of the type 1 vesicular monoamine transporter. Raised intracellular [Ca(2+) ] rapidly releases preloaded [(3) H]5-HT from CD4(+) and CD8(+) T cells indicating that these cells have the capacity for the storage and regulated secretion of 5-HT. Notably, both the expression of tryptophan hydroxylase 1 and monoamine oxidase A, and 5-HT production are significantly greater in CD8(+) compared with CD4(+) T cells. CONCLUSION: These data reveal coordinated changes in 5-HT production, metabolism and storage that may optimize 5-HT secretion from the CD8(+) T cell subset in response to activation stimuli.

Cerebrovascular risk factors and preclinical memory decline in healthy APOE ε4 homozygotes.

OBJECTIVE: To characterize the effects of cerebrovascular (CV) risk factors on preclinical memory decline in cognitively normal individuals at 3 levels of genetic risk for Alzheimer disease (AD) based on APOE genotype. METHODS: We performed longitudinal neuropsychological testing on an APOE ε4 enriched cohort, ages 21-97. The long-term memory (LTM) score of the Auditory Verbal Learning Test (AVLT) was the primary outcome measure. Any of 4 CV risk factors (CVany), including hypercholesterolemia (CHOL), prior cigarette use (CIG), diabetes mellitus (DM), and hypertension (HTN), was treated as a dichotomized variable. We estimated the longitudinal effect of age using statistical models that simultaneously modeled the cross-sectional and longitudinal effects of age on AVLT LTM by APOE genotype, CVany, and the interaction between the two. RESULTS: A total of 74 APOE ε4 homozygotes (HMZ), 239 ε4 heterozygotes (HTZ), and 494 ε4 noncarriers were included. APOE ε4 carrier status showed a significant quadratic effect with age-related LTM decline in all models as previously reported. CVany was associated with further longitudinal AVLT LTM decline in APOE ε4 carriers (p=0.02), but had no effect in noncarriers. When ε4 HTZ and HMZ were considered separately, there was a striking effect in HMZ (p<0.001) but not in HTZ. In exploratory analyses, significant deleterious effects were found for CIG (p=0.001), DM (p=0.03), and HTN (p=0.05) in APOE ε4 carriers only that remained significant only for CIG after correction for multiple comparisons. CONCLUSION: CV risk factors influence age-related memory decline in APOE ε4 HMZ.

Capsaicin receptor: TRPV1 a promiscuous TRP channel.

TRPV1, the archetypal member of the vanilloid TRP family, was initially identified as the receptor for capsaicin, the pungent ingredient in hot chili peppers. The receptor has a diverse tissue distribution, with high expression in sensory neurons. TRPV1 is a nonselective cation channel with significant permeability to calcium, protons, and large polyvalent cations. It is the most polymodal TRP channel, being activated by numerous stimuli, including heat, voltage, vanilloids, lipids, and protons/cations. TRPV1 acts as a molecular integrator of physical and chemical stimuli in peripheral nociceptor terminals and plays a critical role in thermal inflammatory hyperalgesia. In addition, TRPV1 may regulate a variety of physiological functions in different organ systems. Various second messenger systems regulate TRPV1 activity, predominantly by serine-threonine phosphorylation. In this review, we provide a concise summary of the information currently available about this channel.

cGMP-mediated facilitation in nerve terminals by enhancement of the spike afterhyperpolarization.

cGMP has long been suspected to play a role in synaptic plasticity, but the inaccessibility of nerve terminals to electrical recording has impeded tests of this hypothesis. In posterior pituitary nerve terminals, nitric oxide enhanced Ca(2+)-activated K+ channel activity by activating guanylate cyclase and PKG. This enhancement occurred only at depolarized potentials, so the spike threshold remained unaltered but the afterhyperpolarization became larger. During spike trains, the enhanced afterhyperpolarization promoted Na+ channel recovery from inactivation, thus reducing action potential failures and allowing more Ca(2+) to enter. Activating guanylate cyclase, either with applied nitric oxide, or with physiological stimulation to activate nitric oxide synthase, increased action potential firing. Thus, the cGMP/nitric oxide cascade generates a short-term, use-dependent enhancement of release.

Time from ictal subdural EEG seizure onset to clinical seizure onset: prognostic value for selecting temporal lobectomy candidates.

Long-term subdural EEG recording was performed to test the hypothesis that the duration from ictal subdural EEG seizure onset (ECOT) is prognostic for seizure-free outcome following temporal lobectomy. In 48 patients with complex partial seizures, temporal lobectomy was based on invasive localization of the ictal seizure focus. Subdural EEG data were analyzed for association with seizure-free outcome (seizure-free: yes or no) at a minimum of one year following temporal lobectomy. As the duration from ictal subdural EEG seizure onset to clinical seizure onset increased, the odds of being seizure-free postoperatively increased. The best fitting statistical model for predicting seizure-free outcome included seizure onset (unilateral vs. bilateral) and duration from ictal subdural EEG seizure onset to clinical seizure onset. While selection of temporal lobectomy candidates has increasingly emphasized noninvasive recording, some scalp-EEG monitored patients cannot be offered surgery for various reasons, one of which may include ictal EEG seizure onset following clinical seizure onset. When subdural EEG monitoring is performed for selection of temporal lobectomy candidates, analysis of the duration from subdural EEG seizure onset to clinical seizure onset should improve the prognostic value of the subdural EEG data for seizure-free outcome following temporal lobectomy.

Heart rate and heart rate variability changes in the intracarotid sodium amobarbital test.

PURPOSE: Changes in heart rate and heart rate variability have been found in prior studies performed during the intracarotid sodium amobarbital (ISA) test. However, these results are not entirely consistent with current models of differential cerebral involvement in the modulation of the heart. This study was designed to re-investigate this topic with a larger N than has heretofore been used. METHODS: The electrocardiogram was recorded during left and right ISAs in 73 subjects. Raw heart rate and heart rate variability were calculated. RESULTS: Raw heart rate increased during inactivation of either hemisphere, but more so for the right hemisphere. Heart rate variability changes consistent with decreasing parasympathetic tone also were found to occur during either ISA, but to a significant degree, only during right ISA. CONCLUSIONS: The right hemisphere appears to have a greater role in cerebral regulation of cardiac function, perhaps by virtue of the modification of parasympathetic effects.

Fundamental Ca2+ signaling mechanisms in mouse dendritic cells: CRAC is the major Ca2+ entry pathway.

Although Ca(2+)-signaling processes are thought to underlie many dendritic cell (DC) functions, the Ca(2+) entry pathways are unknown. Therefore, we investigated Ca(2+)-signaling in mouse myeloid DC using Ca(2+) imaging and electrophysiological techniques. Neither Ca(2+) currents nor changes in intracellular Ca(2+) were detected following membrane depolarization, ruling out the presence of functional voltage-dependent Ca(2+) channels. ATP, a purinergic receptor ligand, and 1-4 dihydropyridines, previously suggested to activate a plasma membrane Ca(2+) channel in human myeloid DC, both elicited Ca(2+) rises in murine DC. However, in this study these responses were found to be due to mobilization from intracellular stores rather than by Ca(2+) entry. In contrast, Ca(2+) influx was activated by depletion of intracellular Ca(2+) stores with thapsigargin, or inositol trisphosphate. This Ca(2+) influx was enhanced by membrane hyperpolarization, inhibited by SKF 96365, and exhibited a cation permeability similar to the Ca(2+) release-activated Ca(2+) channel (CRAC) found in T lymphocytes. Furthermore, ATP, a putative DC chemotactic and maturation factor, induced a delayed Ca(2+) entry with a voltage dependence similar to CRAC. Moreover, the level of phenotypic DC maturation was correlated with the extracellular Ca(2+) concentration and enhanced by thapsigargin treatment. These results suggest that CRAC is a major pathway for Ca(2+) entry in mouse myeloid DC and support the proposal that CRAC participates in DC maturation and migration.

Temporal lobe seizure interhemispheric propagation time depends on nonepileptic cortical cerebral blood flow.

In some patients with epilepsy, activation of eloquent cortex using various forms of environmental stimulation and mental activity may induce seizures. The increased neuronal activity resulting from cortical stimulation may be associated with increased regional cerebral blood flow. The vascular steal theory of temporal lobe epilepsy suggests that as nonepileptogenic cortical cerebral blood flow (CBFn) increases, temporal lobe epileptogenicity increases as a result, in part, of decreasing interhemispheric propagation time (IHPT). Recently, IHPT has been shown to be a quantitative electrocorticographic measure of temporal lobe epileptogenicity. In the current study, long-term combined subdural-EEG and surface cortical cerebral blood flow (CBF) monitoring was performed to test the hypothesis that IHPT depends upon CBFn. The results show that IHPT is a nonlinear (negative exponential) function of nonepileptic cortical CBF (r=0.507, df=32, t=-2.204, P<0.05). In temporal lobe epilepsy, nonepileptic cortical hypoperfusion may represent a protective mechanism for delaying interhemispheric seizure propagation. The fact that IHPT decreases exponentially with increasing CBFn suggests that small increases in CBFn should substantially decrease IHPT and increase epileptogenicity. This study confirms that inter-hemispheric propagation time depends upon perfusion of nonepileptogenic cortex.

Affective self-report during the intracarotid sodium amobarbital test: group differences.

Emotional reactions are sometimes observed during the intracarotid sodium amobarbital test. For instance, euphoric/indifference reactions can be seen during right hemisphere inactivation and catastrophic reactions may accompany left hemisphere inactivation. Less dramatic changes can also be detected in affective self-report during left and right hemisphere amobarbital tests, with more negative affect reported during left hemisphere inactivation and either neutral or mildly positive affective states reported during right hemisphere inactivation. The current study not only replicated this effect, but in addition, found significant group differences. The first group (right way) showed a pattern of affective self-report during left and right amobarbital tests entirely consistent with prior findings, while a second group (wrong way) showed results that behaved in a diametrically opposite fashion. A third group (no change) showed little, if any, difference in affective self-report during left and right amobarbital tests. The major factor distinguishing the wrong way group from the other two appeared to be an asymmetrical distribution of left and right temporal lobe lesions in the former group. In contrast, the factor differentiating the right way group from the no change group appeared to be the relative degree of left hemisphere inactivation during the left hemisphere amobarbital test. The results are discussed not only in terms of their impact on theories of cerebral lateralization for emotion, but also in terms of methodological issues in this field.

Induction of persistent sodium current by exogenous and endogenous nitric oxide.

Most voltage-gated Na(+) channels inactivate almost completely at depolarized membrane potentials, but in some cells a residual Na(+) current is seen that is resistant to inactivation. This persistent Na(+) current can have a profound impact on the electrical behavior of excitable cells, and the regulation of this property could have important biological consequences. However, the biological signaling mechanisms that regulate the persistence of Na(+) channels are not well understood. This study showed that in nerve terminals and ventricular myocytes nitric oxide (NO) reduced the inactivation of Na(+) current. This effect was independent of cGMP, was blocked by N-ethylmaleimide, and could be elicited in cell-free outside-out patches. Thus, a reactive nitrogen species acts directly on the channel or closely associated protein. Persistent Na(+) current could also be induced by endogenous NO generated enzymatically by NO synthase (NOS). Application of ionomycin to raise the intracellular Ca(2+) concentration in myocytes activated NOS. The NO produced in response to ionomycin was detected with an NO-sensitive fluorescent dye. Persistent Na(+) current was enhanced by the same treatment, and NOS inhibitors abolished both the elevation of NO and the induction of persistent Na(+) current. These experiments show that NO is a potential endogenous regulator of persistent Na(+) current under physiological and pathophysiological conditions.

Induction of vanilloid receptor channel activity by protein kinase C.

Capsaicin or vanilloid receptors (VRs) participate in the sensation of thermal and inflammatory pain. The cloned (VR1) and native VRs are non-selective cation channels directly activated by harmful heat, extracellular protons and vanilloid compounds. However, considerable attention has been focused on identifying other signalling pathways in VR activation; it is known that VR1 is also expressed in non-sensory tissue and may mediate inflammatory rather than acute thermal pain. Here we show that activation of protein kinase C (PKC) induces VR1 channel activity at room temperature in the absence of any other agonist. We also observed this effect in native VRs from sensory neurons, and phorbol esters induced a vanilloid-sensitive Ca2+ rise in these cells. Moreover, the pro-inflammatory peptide, bradykinin, and the putative endogenous ligand, anandamide, respectively induced and enhanced VR activity, in a PKC-dependent manner. These results suggest that PKC may link a range of stimuli to the activation of VRs.

Direct actions of nitric oxide on rat neurohypophysial K+ channels.

1. Nitric oxide (NO) has been shown to modulate neuropeptide secretion from the posterior pituitary. Here we show that NO activates large-conductance Ca2+-activated K+ (BK) channels in posterior pituitary nerve terminals. 2. NO, generated either by the photolysis of caged-NO or with chemical donors, irreversibly enhanced the component of whole-terminal K+ current due to BK channels and increased the activity of BK channels in excised patches. NO also inhibited the transient A-current. The time courses of these effects on K+ current were very different; activation of BK channels developed slowly over several minutes whereas inhibition of A-current immediately followed NO uncaging. 3. Activation of BK channels by NO occurred in the presence of guanylyl cyclase inhibitors and after removal of ATP or GTP from the pipette solution, suggesting a cGMP-independent signalling pathway. 4. The sulfhydryl alkylating agent N-ethyl maleimide (NEM) increased BK channel activity. Pretreatment with NEM occluded NO activation. 5. NO activation of BK channels occurred independently of voltage and cytoplasmic Ca2+ concentration. In addition, NO removed the strict Ca2+ requirement for channel activation, rendering channels highly active even at nanomolar Ca2+ levels. 6. These results suggest that NO, or a reactive nitrogen byproduct, chemically modifies nerve terminal BK channels or a closely associated protein and thereby produces an increase in channel activity. Such activation is likely to inhibit impulse activity in posterior pituitary nerve terminals and this may explain the inhibitory action of NO on secretion.

Ultra-violet light-induced changes in membrane properties in secretory cells.

Illumination with ultra-violet is used widely in physiological experiments for the photolysis of caged compounds. In the peptidergic cells of the pituitary gland, as well as cultured PC12 cells, ultra-violet light was found to produce changes in a number of membrane properties. Light of sufficient intensity to produce rapid photolysis of commonly used caged compounds induced changes in K+ and Ca2+ current, as well as changes in membrane capacitance. All responses to light showed a rapid timecourse, activating in a few ms and decaying within 10-50 ms after illumination ended. Experiments with radical scavengers and with inhibitors of cytochrome p450 and phospholipase A2 failed to block the light responses. These rapid responses to light emphasize that experiments employing ultra-violet light in the photorelease of physiological and pharmacological agents require special care for control of light artifacts.

Effects of ivermectin and midecamycin on ryanodine receptors and the Ca2+-ATPase in sarcoplasmic reticulum of rabbit and rat skeletal muscle.

1. Ryanodine receptor (RyR) Ca2+ channels in the sarcoplasmic reticulum (SR) of skeletal muscle are regulated by the 12 kDa FK506- (or rapamycin-) binding protein (FKBP12). Rapamycin can also activate RyR channels with FKBP12 removed, suggesting that compounds with macrocyclic lactone ring structures can directly activate RyRs. Here we tested this hypothesis using two other macrocyclic lactone compounds, ivermectin and midecamycin. 2. Rabbit skeletal RyRs were examined in lipid bilayers. Ivermectin (cis, 0.66-40 microM) activated six of eight native, four of four control-incubated and eleven of eleven FKBP12-'stripped' RyR channels. Midecamycin (cis, 10-30 microM) activated three of four single native channels, six of eight control-incubated channels and six of seven FKBP12-stripped channels. Activity declined when either drug was washed out. 3. Neither ivermectin nor midecamycin removed FKBP12 from RyRs. Western blots of terminal cisternae (TC), incubated for 15 min at 37 C with 40 microM ivermectin or midecamycin, showed normal amounts of FKBP12. In contrast, no FKBP12 was detected after incubation with 40 microM rapamycin. 4. Ivermectin reduced Ca2+ uptake by the SR Ca2+-Mg2+-ATPase. Ca2+ uptake by TC fell to approximately 40% in the presence of ivermectin (10 microM), both with and without 10 microM Ruthenium Red. Ca2+ uptake by longitudinal SR also fell to approximately 40% with 10 microM ivermectin. Midecamycin (10 microM) reduced Ca2+ uptake by TC vesicles to approximately 76% without Ruthenium Red and to approximately 90 % with Ruthenium Red. 5. The rate of rise of extravesicular [Ca2+] increased approximately 2-fold when 10 microM ivermectin was added to TC vesicles that had been partially loaded with Ca2+ and then Ca2+ uptake blocked by 200 nM thapsigargin. Ivermectin also potentiated caffeine-induced Ca2+ release to approximately 140% of control. These increases in Ca2+ release were not seen with midecamycin. 6. Ivermectin, but not midecamycin, reversibly reduced Ca2+ loading in four of six skinned rat extensor digitorum longus (EDL) fibres to approximately 90%, and reversibly increased submaximal caffeine-induced contraction in five of eight fibres by approximately 110% of control. Neither ivermectin nor midecamycin altered twitch or tetanic tension in intact EDL muscle fibres within 20 min of drug addition. 7. The results confirm the hypothesis that compounds with a macrocyclic lactone ring structure can directly activate RyRs. Unexpectedly, ivermectin also reduced Ca2+ uptake into the SR. These effects of ivermectin on SR Ca2+ handling may explain some effects of the macrolide drugs on mammals.

ATP inhibition and rectification of a Ca2+-activated anion channel in sarcoplasmic reticulum of skeletal muscle.

We describe ATP-dependent inhibition of the 75-105-pS (in 250 mM Cl-) anion channel (SCl) from the sarcoplasmic reticulum (SR) of rabbit skeletal muscle. In addition to activation by Ca2+ and voltage, inhibition by ATP provides a further mechanism for regulating SCl channel activity in vivo. Inhibition by the nonhydrolyzable ATP analog 5'-adenylylimidodiphosphate (AMP-PNP) ruled out a phosphorylation mechanism. Cytoplasmic ATP (approximately 1 mM) inhibited only when Cl- flowed from cytoplasm to lumen, regardless of membrane voltage. Flux in the opposite direction was not inhibited by 9 mM ATP. Thus ATP causes true, current rectification in SCl channels. Inhibition by cytoplasmic ATP was also voltage dependent, having a K(I) of 0.4-1 mM at -40 mV (Hill coefficient approximately 2), which increased at more negative potentials. Luminal ATP inhibited with a K(I) of approximately 2 mM at +40 mV, and showed no block at negative voltages. Hidden Markov model analysis revealed that ATP inhibition 1) reduced mean open times without altering the maximum channel amplitude, 2) was mediated by a novel, single, voltage-independent closed state (approximately 1 ms), and 3) was much less potent on lower conductance substates than the higher conductance states. Therefore, the SCl channel is unlikely to pass Cl- from cytoplasm to SR lumen in vivo, and balance electrogenic Ca2+ uptake as previously suggested. Possible roles for the SCl channel in the transport of other anions are discussed.

Quantitative analysis of hemispatial neglect in the intracarotid sodium amobarbital (ISA) test.

There are dramatic changes in the electroencephalogram of the inactivated hemisphere in the intracarotid sodium amobarbital test. One of the more profound behavioral changes during this procedure is left hemispatial neglect accompanying right hemisphere inactivation. The present study was designed to ascertain whether there was a clear relationship between the degree of hemispheric inactivation (as measured by the electroencephalogram) and the degree of left hemispatial neglect during this procedure. Sixty-nine participants undergoing right hemisphere intracarotid sodium amobarbital testing were presented with a random letter cancellation test at various points during the procedure. Neglect was quantified as significant, moderate, minimal, or none, based on how many target letters the patients missed. The simultaneous electroencephalogram from each of these testing points was spectrally analyzed and topographic maps were generated. The degree of neglect was then compared with the comparable topographic map. It was found that as the amobarbital-induced right hemispheric dysfunction regressed, the degree of neglect lessened in a systematic fashion, as did the profound electroencephalographic changes induced by the drug. Thus, there is a clear relation between the degree of hemispheric inactivation induced by the amobarbital and the degree of left hemispatial neglect. This relationship held regardless of side of hemispheric language dominance or epileptic focus. These results replicate previous findings that right hemisphere inactivation during the intracarotid sodium amobarbital test results in left hemispatial neglect. They extend these findings by clearly showing that neglect changes in a quantitative fashion (rather than being an all-or-none phenomenon) and further, show that there is a clear relationship between the severity of neglect and the degree of hemispheric dysfunction.

Membrane excitability in the neurohypophysis.

The application of patch clamp technology to the neurohypophysis has contributed significantly to our understanding of the membrane events governing neuropeptide secretion. Nerve terminals within the posterior pituitary are now known to contain three distinct K+ channel subtypes, a rapidly inactivated channel (responsible for A current), a Ca(2+)-activated K+ channel, and a delayed rectifier channel. Activation of a D2 subtype dopamine receptor reduces both the A-current and current through the Ca2+ activated K+ channels. These actions can be expected to enhance neuropeptide release. Release of nitric oxide reduces the amplitude of the A-current but enhances current through the Ca(2+)-activated K+ channel, and this would provide mechanisms for more complex modes of regulation of release. Neurohypophysial nerve terminals also express at least two types of Ca2+ channels. The first is a dihydropyridine-sensitive, "L-type" channel. The second resembles the "N-type" Ca2+ channel. Patch clamp recordings have shown that tissue culture medium conditioned by exposure to T-cells enhances this Ca2+ current. This may represent a mechanistic link between activation of the immune system and functional membrane changes within the neurohypophysis. GABA-activated Cl- channels have also been described within the neurohypophysis, and these receptors can be modulated by neuroactive steroids. One of these, the progesterone derivative allopregnanolone, changes dramatically during female reproductive transitions. Such an interaction could represent a pivotal mechanistic step in the onset of parturition, and the neurohypophysial GABA receptor may hold promise as a target of therapeutic intervention in clinical cases of preterm labor.

Neuroanatomical correlates of pleasant and unpleasant emotion.

Substantial evidence suggests that a key distinction in the classification of human emotion is that between an appetitive motivational system association with positive or pleasant emotion and an aversive motivational system associated with negative or unpleasant emotion. To explore the neural substrates of these two systems, 12 healthy women viewed sets of pictures previously demonstrated to elicit pleasant, unpleasant and neutral emotion, while positron emission tomographic (PET) measurements of regional cerebral blood flow were obtained. Pleasant and unpleasant emotions were each distinguished from neutral emotion conditions by significantly increased cerebral blood flow in the vicinity of the medial prefrontal cortex (Brodmann's area 9), thalamus, hypothalamus and midbrain (P < 0.005). Unpleasant was distinguished from neutral or pleasant emotion by activation of the bilateral occipito-temporal cortex and cerebellum, and left parahippocampal gyrus, hippocampus and amygdala (P < 0.005). Pleasant was also distinguished from neutral but not unpleasant emotion by activation of the head of the left caudate nucleus (P < 0.005). These findings are consistent with those from other recent PET studies of human emotion and demonstrate that there are both common and unique components of the neural networks mediating pleasant and unpleasant emotion in healthy women.