Human Brain Software

Flash Brain Anatomy

This course gives you access to a full online course and software to learn more about the brain than you ever thought possible in a short amount of time. This software contains detailed, 3D brain models, animations to display concepts, hundreds of educational courses, a neuroanatomy atlas, and compatibility with most web browsers. You will also have access to a full online suite of tutors. Neuroanatomy is one of the hardest parts of anatomy to learn, and learning the brain will really be a lot easier if you had a detailed model to base your knowledge off. This software makes the brain as simple as possible, while also giving you a way to learn it throughly. This model simplifies a very complex subject that most people struggle with Don't be one of the people that doesn't know what to do with the brain model! This course is designed to teach you everything about the brain while keeping the lessons manageable and learning at your own pace. Continue reading...

Flash Brain Anatomy Summary

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Highly Recommended

The interface is user friendly with its intuitive layout. Also, the addition of the prompt, with expert advice sets it apart from all the other similar programs. The Flash Brain Anatomy installation process is clean and without any unpleasant surprises like hidden toolbars, adds or anything like that. However, the installation process takes a bit longer than expected and you actually have to go through ten steps before the installation is complete, but that can hardly be considered a downside though.

I personally recommend to buy this software. The quality is excellent and for this low price and 100% Money back guarantee, you have nothing to lose.

METHInduced Effects in Human Brain Imaging Studies

Months.290 The persistent decrease in striatal metabolism suggests long-lasting changes. Consistent with findings in post-mortem human brain, individuals with METH abuse histories have significant decreases in binding of the PET DAT radioligand 11C WIN-35,428 in the caudate and putamen.291 Other PET studies using compounds targeting the DAT have confirmed decreased DAT binding in the caudate and putamen in current abusers,292 recently detoxified subjects,293 and in those abstinent for upwards of 11 months.234 Studies have also linked abnormalities in D2 receptors and substance abuse given that lower levels are found in alcoholics,294 and cocaine295 and heroin296 abusers. In line with these data, D2 receptor levels are lower in the caudate and putamen of METH abusers, as measured by PET 11C raclopride267 (but see Reference 293). Taken together, these data clearly show abnormal brain function in METH abusers. Future studies are needed to determine permanent neurochemical deficits...

Who Or What Killed Einstein

Historically speaking, altered forms of perception in which an overall view of reality is immediately discerned and felt in a kind of joyous flash of insight, are the sole domain of the religious mystic, those persons who claim, rather controversially and often with alarming vigour, to have directly experienced 'ultimate truths' about reality. Since most mystics and religious visionaries have employed various techniques with which to foster their insights like fasting, yoga, meditation, perceptual isolation etc, than this again testifies to the fact that the normal human brain is somehow constrained in its mindful activity and that the chemical system which does the constraining can be overcome or be bypassed by engaging in various so-called spiritual disciplines. For most of us, such esoteric endeavours, regardless of whether or not they do actually yield valid knowledge, are perhaps a little beyond our normal way of life, and we might therefore wish to stick with less suspect...

Genes encoding human cannabinoid receptors

The human CB1 cDNA was isolated by Gerard et al. (1991) from a human brain stem cDNA library using a 600 bp DNA probe and polymerase chain reaction. The deduced amino acid sequences of the rat and human receptors showed that they encode protein residues of 473 and 472 amino acids respectively with 97.3 homology. These proteins share the seven hydrophobic transmembrane domains and residues common among the family of G-protein receptors (Matsuda et al., 1991 Gerard et al., 1991 Shire et al., 1995). The human and rat CBX receptors also share pharmacological characteristics including the inhibition of adenylate cyclase activity via Gi o in a stereoselective and pertusis sensitive manner following activation by cannabinoids (Devane et al., 1988 Matsuda et al., 1990 Gerard et al., 1991). The CBj receptors alter potassium channel conductance (Hampson et al., 1995) and decrease calcium channel conductance (Mackie and Hille, 1992).

Gene Structure and Expression Studies

Partial RT-PCR products are used as Northern blotting probes. Probes are hybridized to nylon membranes that had been blotted with 40 g of human brain total RNA or 10 g of human hippocampal poly A+ RNA (Clontech, Palo Alto, CA). Human brain RNAs from different region were used as quantitative RT-PCR templates. The ratio between RT-PCR products corresponded to that of iso-forms.

Psychological psychiatric

The effects of chronic marijuana smoking on human brain function and cognition have been further investigated (62). Normalized regional brain blood flow and regional brain metabolism, measured using PET scanning with 15O, were compared in 17 frequent marijuana users and 12 nonusers. Testing was performed after at least 26 hours of monitored abstinence in all subjects. Marijuana users had hypoactivity or reduced brain blood flow in a large region of the posterior cerebellum compared with controls. This is consistent with what was reported in the only previous PET study of chronic marijuana use (80). The cerebellum is hypothesized to have input to aspects of cognition, specifically timing, the processing of sensory information, and attention and prediction of real-time events. Users often report that marijuana smoking is followed by alterations in the sense of time and less efficient cognitive processing.

Tissue Plasminogen Activator and Growth Associated Protein

Adaptive responses to stressful events comprise physiological processes and behavior aimed at sustaining homeostasis, while severe stress may modify this response and lead to exaggerated fear reaction and persisting anxiety and depression. At the center of the functional neuroanatomy of the stress circuit are the amygdala and the hippocampus, which both exhibit dendritic remodeling following repeated inescapable stress. Although several key players of the stress circuit have been characterized, the mechanism that underlies stress-induced neural plasticity leading to anxiety and associated cognitive impairment remains to be elucidated. Recently, Pawlak and coworkers (2003) identified acute restraint stress-induced upregulation of the serine protease tissue-plasminogen activator (tPA) in the amygdala as a critical mechanism in stress-related neural remodeling that is either adaptive and directed toward attenuation of the deleterious impact of stress on the brain or is reflecting the...

The Endocannabinoid System

CB1 receptor expression in the brain. Cannabinoid receptor distribution was studied by means of autoradiography of ligand-receptor binding on slide-mounted rat brain sections (24, 33), by in situ hybridization (ISH) (34-36), by autora-diography in human brain (37), by immunohistochemistry (IHC) (38-41), and by agonist-stimulated 35S GTPyS binding to slide-mounted sections (42, 43). Expression studies showed very early that CB1 receptor is one of the most

Chapter Five The Mushroom And The Synapse

However, before we can explore the exciting insights that such an informational model of reality yields, we must start from the beginning, that is, we must look more closely at the obviously important physical relationship between psilocybin and the human brain. That might sound rather intimidating but, lets face it, getting to intimate grips with Nature in order to ascertain the meaning of life, consciousness and everything that really matters was never going to be a simple piece of cake. I assure you that its a deeply fascinating piece of cake though.

Tissue Levels of Anandamide Continued

Measurable amounts of anandamide (Schuel etal., 2002). A small amount of anandamide was also found in human milk (Fride et al., 2001). In addition, anandamide was detected in rat plasma collected by decapitation or by cardiac puncture and in the sera from normal donors and patients with endotoxin shock (Wang etal., 2001). Giuffrida, Rodriguez de Fonseca, Nava, et al. (2000) reported that the administration of AM404, an anandamide transport inhibitor, to rats induced the elevation of the plasma anandamide level. On the other hand, Yang et al. (1999) described that the levels of anandamide in the rat brain, spleen, testis, liver, lung, and heart were below the detection limit (

Introducing The Neuronal Brain

As mentioned, the brain consists of individual information-processing nerve cells or neurons. It is estimated that the human brain contains some 13 or so billion of them. This is an astronomical amount, comparable to the vast number of stars in our galaxy. It is also more than twice the number of people alive on the planet. These 13 billion neurons are the essential 'wetware' of the brain and, massed together with other cells that provide support and energy, they form the spongy grey matter residing within our skulls.

METHInduced Alterations in Intracellular Messenger Systems in Humans

Results from post-mortem human studies addressing METH-induced changes in receptors and intracellular messenger systems are generally in line with changes seen in animal studies (Figure 4.1). For example, inhibitory G proteins, Gai1 and Gai2, and Gao levels are reduced (32 to 49 ) in the NAC of METH (and heroin) abusers.233 These results are consistent with rodent studies showing that cocaine and heroin decrease inhibitory G protein levels in the NAC.185,186 Experiments exploring the effects of METH specifically on G protein levels have not been conducted in animals. Although the lower inhibitory G protein levels could represent a preexisting deficit, it is more likely that they are the result of neural adaptations employed to restore balance in response to chronic METH stimulation. Inhibitory G proteins are linked to a number of receptors including D2. A compensatory down-regulation of the D2 receptor pathway, or D2 receptors specifically, is consistent with imaging studies showing...

Patricia Tagliaferro Alberto J Ramos Emmanuel S Onaivi Sergio G Evrard Maite Duhalde Vega and Alicia Brusco

One of the major goals for the use of digital image analysis systems in neuroanatomy is to visualize structures, cells, or other tissue components in order to compare various populations. In addition, digital image analysis allows semi-quantification of cell labeling because it is capable of measuring simultaneously the staining intensity, location, size, and shape of labeled profiles. In the present work, the morphological changes in the CB1 hippocampal area and corpus striatum induced by chronic treatment with the synthetic CB1-receptor agonist WIN55,212-2 were analyzed as an example of digital image analysis application. Twice-daily treatment for 14 d with the CB1-receptor agonist demonstrated significant changes in the expression of neuronal cytoskele-tal proteins and in neuronal morphology, as evidenced by immunocytochemical and digital analysis studies. However, changes in the expression of astroglial cytoskeletal proteins were not found.

Applications of Image Analysis in the Study of the CNS Morphology

One of the primary reasons for using digital image analysis in neuroanatomy is to statistically summarize and evaluate a structure to allow comparisons among populations. Digital image analysis offers a wide range of possibilities that are very useful when analyzing morphological changes. In this particular study, densitometry and morphometry, which are widely utilized functions of the digital image analysis, were used. Densitometry was employed to estimate the relative concentrations of different antigens detected by immunocytochem-istry, while morphometry was used to study cell morphology and the relative area covered by cellular projections. Digital image analysis allows one to semi-quantify immunocytochemical experiments because it is capable of measuring simultaneously the labeling intensity, localization, size and shape of the labeled profiles.

Chemistry And The Mind

Obviously the human brain is a finely tuned information processing instrument. If the neuronal events substantiating some kinds of information processing are pushed too far from some criteria, or if neuronal events are 'read' by an erroneous contextual system, then faulty processing occurs with its resultant negative disruption of consciousness.

Technique Overview PET

PET scanners are able to measure the regional and temporal concentrations of positron emitting nuclides in small (4x4x4 mm) volumes of the human body (Phelps 1991). They therefore allow the extension of radioligand binding studies to the living human brain, provided that suitable labeled compounds are available (Gatley 1996). For use in PET, carbon, nitrogen, and oxygen all have positron-emitting isotopes 11C (t1 2 20 min), 13N (t1 2 10 min) and 15O (t1 2 2 min). Of these, 11C is perhaps most useful because it can be used to label organic compounds, including drugs of abuse, without altering their pharmacokinetics or binding profiles. In addition, many compounds labeled with 18F (t1 2 110 min) are useful PET tracers, because fluorine can often replace -H or -OH with retention of activity.

Kappaopioid Receptors

The endogenous opioidergic system has been implicated as a primary mediator of the behavioral and reinforcing effects of cocaine.94 (See Reference 139 for more information on the interaction of cocaine with the opioid system including the mu- and delta-opioid receptors.) Pharmacological and molecular cloning studies have recently reported the existence of at least three subtypes of k-opioid receptors.140-147 Receptor mapping studies have demonstrated that both Kj-opioid receptor and K2-opioid receptor subtypes are prevalent throughout the mesocorticolimbic pathways in the human brain.26,148,149 One striking difference in the localization of the two subtypes is reflected by the intense localization of the K2-opioid receptor subtype in the ventral or limbic sectors of the striatum and the nucleus accumbens in the human brain.149 Conversely, the K1-opioid receptor subtype may preferentially localize to the dorsal or sensorimotor areas of the human striatum.26 Based on their...

Regulation of Kappa Opioid Receptors by Cocaine

Recently, pharmacological binding assays to selectively label the K2-opioid receptor subtype have been developed using the opioid antagonist 125I IOXY in the presence of drugs occluding binding to the and K-opioid receptor subtypes.151 This strategy was used in ligand binding and in vitro autoradiography assays to assess the regulation of the K2-opioid receptor subtype after cocaine exposure in post-mortem human brain (death was from cocaine overdose) (Figure 5.1).149,158 Quantitative region-of-interest densitometric measurements of 125I IOXY binding demonstrated a twofold elevation in the anterior and ventral sectors of the caudate and putamen and in the nucleus accumbens of human cocaine overdose victims as compared to drug-free and age-matched control subjects. In subjects who experienced paranoia and agitation prior to their death, K2-opioid receptors were also elevated in the amygdala.104,158

CB1 Receptor Subtypes

Shire et al. (1995) have isolated a spliced variant of CB1 cDNA (CB1A) fromahuman lung cDNA library. CB1A mRNA is present in human brain tissue, its distribution pattern matching that of CB1 mRNA. It has also been detected in peripheral tissues. The spliced variant resembles the CB1 receptor in its affinity for 49-THC, CP55940 and -(+)-WIN55212, and it also has at least two signal transduction mechanisms in common with the CB1 receptor (Rinaldi-Carmona et al. 1996a). However, the central and peripheral concentrations of CB1A mRNA are far below those of CB1 mRNA (Shire et al. 1995). Onaivi et al. (1996) have discovered three distinct CB1 mRNAs in brain tissue from C57BL 6 mice, although only one CB1 receptor cDNA. C57BL 6 mice were less sensitive to the hypothermic and antinociceptive effects of 49-THC than two other mouse strains in which only one CB1 mRNA was detectable.

Putative Neuroprotective Effects Of Other Naes

N-Oleoylethanolamine is also a predominant NAE species in the injured rat brain (56), and it has also been found to be the major NAE species in a human brain that has suffered a hemispheric stroke (133). As early as 1975 (175), N-oleoylethanolamine was synthesized as an inhibitor of ceramidase, the enzyme that degrades ceramide. Ceramide is involved in the regulation of apoptosis and cell proliferation (176,177). Cannabinoid-induced apoptosis in glioma cells is mediated via formation of ceramide (178-181). On a tentative basis, it can be suggested that anandamide-induced apoptosis may be aggravated by the presence of N-oleoylethanolamine because this leads to increased formation of ceramide. There are numerous studies in which N-oleoylethanolamine has been shown to facilitate the apoptosis-inducing effect of different compounds (182-188) mediated via increased ceramide levels. However, it has also been reported that N-oleoylethanolamine decreases ceramide levels in JB6 P+ cells by an...

Transport Mechanisms within Living Brain Tissue

The extracellular space represents approximately 20 of the total human brain volume. Its geometry can be compared to that of the water phase in an aqueous foam. Drug transport in this region can often (surprisingly well) be described based on Fick's second law of diffusion. Important aspects to be taken into account include the volume fraction in which diffusion can take place and the tortuosity of the diffusion pathways. Recently, the group of Charles Nicholson studied the effects of the geometry of CNS cells on the tortuosity of the extracellular space (42-44). Considering uniformly spaced convex cells, they found that the presence of dead-space micro-domains can help to better understand the difference between the experimentally measured tortuosity and the theoretically calculated one. It has to be pointed out that many brain diseases can significantly affect the conditions for drug transport within the CNS (45,46). For example, cellular swelling can lead to a significant shrinkage...

Contemplating Evolution

This leads me to think that the assertion that the human brain is the most complex organ we know of is in fact a fallacy and that the biospheric Gaian system in its interconnected totality is far and away more complex and integrated than a single human brain. It must be. A brain cannot be understood properly unless the context in which it exists is taken into account. This context is the environment with its vast network of language-like relations. Nothing remains isolated within the environment. All organisms derive their meaning and their function according to the role they play in the entire Gaian system. The point then, is that Gaia is unimaginably more complex than the parts of which it is composed. Since the human brain is complex enough to embody intentional intelligence and since much of its firing activity can only be understood in the light of its intentional intelligence, I believe it tenable that, in an analogous way, evolution itself represents the on-going intent of an...

Environmental Awareness

To take another example, if we think about the unusually rapid evolution of the human brain, then each incremental increase in size (presumably derived via mutation variation) must have met with many specific environmental circumstances with which to immediately highlight those slight increases in capacity so that a reproductive advantage was achieved. Each mutation in hominid brain size was

Gene Expression Profiling Experiments

Using microarrays, differences in gene expression can be detected on a whole genome level for different behavioral responses, treatment modalities, or brain regions. Several groups have already tried to use this technique to identify novel candidate genes for depression and anxiety and their treatment. In the search of the common final pathway of antidepressant action, gene expression changes following chronic antidepressant treatment have been analyzed (Ya-mada et al. 2000,2001). Our group has searched for genes commonly regulated by two antidepressants with different receptor binding profiles, paroxetine and mirtazapine (Landgrebe et al. 2002). Another approach is to identify genes differentially regulated in brain regions that have been associated with different cognitive functions, including anxiety behavior (see, for example, Dent et al. 2001). So far, however, no strong candidate that has also been validated in human genetic studies has been brought forward. A series of...

CYP2D Enzyme in Brain

An uneven distribution of CYP2D activity was also observed in preliminary studies of dissected monkey (C. Aethiops) brain (Tyndale et al., unpublished data). Subcellular preparations of the nucleus accumbens, amygdala, and parietal cortex oxidized sparteine at rates of 300 to 600 picomoles per milligram of protein per hour (pmol mg protein hour). (By contrast, the rate in monkey hepatic microsomes was 62,000 pmol mg protein hour). The rate in striatum, hippocampus, and temporal and olfactory cortex was approximately 75 pmol mg protein hour. The spinal cord, frontal cortex, midbrain, medulla, and cerebellum had negligible activity. CYP2D activity in monkey brain displayed the stereoselective inhibition by quinidine and quinine that is characteristic of monkey liver CYP2D and human liver CYP2D6. Regional variation in the distribution of CYP2D messenger ribonucleic acid (mRNA) in rat and human brain has also been observed (Tyndale et al., unpublished observations). There is molecular...

An der Spritze hngen German colloquial

Anandamide Endogenous cannabis-like substance naturally present in the human brain. In 1988, Allyn Howlett of St Louis University Medical School in USA discovered a specific protein receptor for THC in mouse nerve cells - a protein that only THC and its relatives dock onto. Two years later, Tom Bonner's group at the National Institute of Mental Health in USA pinpointed the DNA that encodes the same receptor in rats. Several laboratories set to work on the problem and, 1992 Mechoulam's group in Jerusalem was the first to come up with an answer, in the form of a greasy, hairpin-shaped chemical. The researchers dubbed it anandamide, from an-anda , the Sanskrit word for bliss. Finding a cannabinoid receptor and anan-damide implies that THC - unlike alcohol -has a quite precise modusoperandi that taps into a specific brain function. Presumably the drug binds to nerves that have the receptor, and the nerves respond in turn by altering their behaviour. The classic effects of marijuana...

Introduction Of Hallucinogens

If one were to look for landmarks in the study of hallucinogens in the nearly forty years since LSD-25 was first developed in a Swiss laboratory in 1938, a good many possibilities come to mind. One would be the discovery in that same year that a cult of divine psychedelic mushrooms had survived among Mexican Indians, and the rediscovery and systematic investigation of that cult in the mid-1950's. Another would be the identification of the seeds of morning glories as the sacred Aztec hallucinogen ololiuhqui in 1941, and the startling finding nearly twenty years later that its active principles are closely related to lysergic acid derivatives. Still another would be R. G. Wasson's definition of Soma as the psychotropic fly-agaric mushroom (1968). These discoveries have accompanied the realization over the past several years that the most important botanical hallucinogens are structurally related to biologically active compounds occurring naturally in the brain. For example, psilocybine...

Possible mechanisms for effects on brain morphology

During adolescence there are also significant developmental changes ongoing in the human brain (Dekaban and Sadowsky, 1978 Dobbing and Sands, 1973 Jernigan et al., 1991 Reiss et al., 1996). The study by Reiss et al. (1996, page 1763) has shown Prominent age related changes in gray matter, white matter and CSF , which appear to reflect ongoing maturation and remodeling. The changes include increases in myelinization and decreases in gray matter. Huttenlocher (1979) demonstrated that there is a significant increase in frontal cortex synaptic density in humans between birth and age 2 and that it then declines to adult levels between ages 2 and 16. Purves (1988) has suggested that due to the rapid somatic growth during adolescence, there may be a need for neural plasticity to persist to accommodate these changes. Thus, data show that during adolescence there is an active process of brain maturation involving both gray and white matter. Of interest here also would be the possible effects...

Neurochemical Pathology Of Cocaine Delirium

Neurochemistry Addiction

A number of different studies point to a possibility of a defective interaction of cocaine with the DA transporter in the etiology of cocaine delirium. The effects of chronic, intermittent cocaine treatment paradigms on the labeling of the cocaine recognition sites on the DA transporter have been investigated in rat studies. Neuroadaptive changes in the DA transporter have been characterized with a number of different radioligands, including 3H cocaine, the cocaine congeners 3H WIN 35,428 and 125I RTI-55, and more recently with 125I RTI-121 (for review, see Reference 29). In contrast to the classic DA transport inhibitors ( 3H mazindol, 3H GBR 12935, and 3H nomifensine), the cocaine congeners ( 3H WIN 35,428, 125I RTI-55, and 125I RTI-121) label multiple sites with a pharmacological profile characteristic of the DA transporter in rat, primate, and human brain.30-32 Chronic treatment of rats with intermittent doses of cocaine demonstrated a twofold to fivefold increase in the apparent...

Brief History Of Psychedelics

Female Stimulation Guide

Try to imagine yourself as a neolithic human, most of your attention given to day-by-day survival, the more complex areas of your brain just beginning to develop. Now ingest say, a handful of psilocybin mushrooms, or the psychedelic root of the African Iboga plant. Imagine what wealth of images and information would now be flowing through your mind In his recent book, Food of the Gods, Terence McKenna presents a plausible hypothesis that homosapiens descended from psychedelic-using hominids. The ability of psychedelics to facilitate development of the human brain is an important part of his theory.

Ontogeny of the Endogenous Cannabinoid System

With regard to humans, data about the appearance and location of CB1 receptors in the developing brain are still very limited (Mailleux and Vanderhaeghen 1992a Glass et al. 1997 Biegon and Kerman 2001 Mato et al. 2003). There is a significant population of cannabinoid receptors at week 19 of gestation that is functionally coupled to signal transduction mechanisms. These receptors are present in the same areas as in the adult human brain and seem to increase progressively in number from early prenatal stages to adulthood (Mato et al. 2003).

Measurement of Cannabinoid Receptor Density

CB1 Receptor Mapping Autoradiographic studies with high-affinity THC analogs both in rat brain tissue (Herkenham et al. 1990) and in postmortem human brain tissue (Thomas et al. 1992 Biegon and Kerman 2001) have demonstrated high concentrations of cannabinoid receptors in the basal ganglia and especially in its outflow nuclei, the globus pallidus, and substantia nigra. High concentrations are also found in hippocampus and cerebellum. The cerebral cortex, especially the cingulate gyrus, also has a fairly high CB1 receptor density. Some other regions, including most of the brainstem and the thalamus, contain few CB1 receptors. Most autoradiographic studies using postmortem human brain tissue have involved schizophrenic subjects, since a link has been suggested between brain cannabinoid systems and schizophrenia (Arseneault et al. 2004), based, in part, on a high density of CB1 receptors in brain areas implicated in schizophrenia (Biegon and Kerman 2001). Dean and colleagues studied...

Cholinergic Adaptations In Smokers

Another important question relates to how long the receptor upregulation lasts. In rodents, 3H nicotine binding is elevated in brain for up to 3 days, and normalizes to baseline values within 7 days of nicotine withdrawal,26 whereas in living human tobacco smokers abstinent for 4 to 9 days, nAChR measured using 123I 5-IA-85380 is elevated compared to age-matched never smokers suggesting that the receptor has not yet normalized at 1 week of abstinence.27 In post-mortem human brain, high-affinity nicotine binding in ex-smokers ( 2 months) is similar to that of the nonsmokers, suggesting that the receptor normalized within a 2-month period of time.4-6 In a preliminary sample of living human smokers, this time frame is similar.28 Thus, while the time period necessary for normalization is still unclear, it is apparent that the time frame for normalization in humans is longer than that noted in rodents.

Beyond the Role of DA in Nicotine Reinforcement

Electrophysiological data show that while pulses of ACh enhance DA neuron activity as one might expect with acute nicotine exposure, simulation of steady states of human nicotine concentrations82 quickly results in desensitization of the midbrain nAChRs.47 Indeed, striatal syn-aptosome preparation used to measure DA release shows that much lower doses of nicotine are required for desensitization than for activation of nAChRs.24,83 This acute tolerance might account for smoker reports that the first cigarette of the day is most pleasurable.84 In human brain, P2*nAChR binding is prolonged for as long as 5 h after a smoking episode,85 begging the question as to why people continue to smoke throughout the day. Research using electrochemical cyclic voltammetry shows that nAChR regulation of DA release depends upon the state of the DA neuron during nicotine application.86,87 When DA neurons are held in a tonic or resting state, nicotine decreases DA release, but when DA neurons are in a...

Investigating The Earths Alchemical Skin

Since DMT is believed, strangely enough, to occur naturally in the human brain (it has been found in blood, urine and spinal fluid and precursor enzymes for it have been found in brain tissue), it was apparent to Strassman that an understanding of its action might shed some light on the development and possible treatment of endogenous hallucinatory conditions like schizophrenia. It is in this way that clinical science comes to make anti-psychotic drugs, substances which can block pathological forms of thought as evident in conditions like schizophrenia. Once you understand the neurochemical events which accompany abnormal states of mind, then you are in a position to develop drugs to treat such conditions. Although the study of mystical experiences and neurochemistry might seem like compelling science, the fact of the matter is that most scientists exercise great caution when it comes to explaining, in scientific terms, something as precious and as guarded as the mystical experience....

Neurons Structure And Environment

Axo Axonic

The neurons from which NTs are released number more than 7 billion in the human brain. Each (Fig. 1.2) consists of a cell body, the soma or perikaryon, with one major cytoplasmic process termed the axon, which projects variable distances to other neurons, e.g. from a cortical pyramidal cell to adjacent cortical neurons, or to striatal neurons or to spinal cord motoneurons. Thus by giving off a number of branches from its axon one neuron can influence a number of others. All neurons, except primary sensory neurons with cell bodies in the spinal dorsal root ganglia, have a number of other, generally shorter, projections running much shorter distances among neighbouring neurons like the branches of a tree. These processes are the dendrites. Their

Morphine Stimulates The Expression Of Adhesion Molecules On Endothelial Cells

We, therefore, subsequently examined the effects of morphine on the expression of adhesion molecules in a primary culture prepared from human brain microvasculature endothelial cells (HBMEC) isolated from individuals with pathological conditions. Human brain microvascular endothelial cells (HBMEC) were isolated from surgical brain tissue, and grown to confluency in 96-well plates. They were then treated with either morphine (0.42, 4.2, or 42 (iM) or control vehicle for 4 hr or 20 hr. The medium was then removed, and the monolayer cells were fixed with acetone methanol (1 1) for 20 min, air dried, and stored at -20 C. The adhesion molecules, ELAM, VCAM and ICAM, were examined using ELISA analysis, in triplicate, according to previously published procedures (Stins et al., 1997).

Life regulation through the high and low cytotoxicity

These alkaloids can activate AChE or inhibit it by influence of enzyme AChE (Figure 81). As in cases of the Amaryllidaceae alkaloids, AChE can be inhibited. As a result of this, acetylcholine activity increases. Acetyl-choline activity is needed for human brain function. It seems that Amaryllidaceae alkaloids have a wide biological regulatory ability. It is known that lycorine, one of the most important Amaryllidaceae alkaloids, is actively antiviral. Pseu-dolycorine and pretazettine are active against several types of leukaemia by the inhibition of protein synthesis and prevention of peptide-bond formation358. Galanthanine has analgesic, anticholinergic and anticholinesterase properties. The minor Amaryllidaceae alkaloids studied by Abd El Hafiz et al358 are also biologically active. The lycorine-type alkaloid (pratorinine) and the crinine-type alkaloid (6a-hydroxybuphanisine) showed a moderate cytotoxic activity. Moreover, ( )-spectaline, apiperedine alkaloid isolated...

CNS Distribution of the Muscarinic Receptors

While a great diversity of behavioral, physiological and biochemical effects is mediated by mAChRs, the identities of the molecular subtypes responsible for any given neuronal function remain elusive. The complex pharmacology of the mAChR subtypes, together with the lack of drugs with high selectivity has made it difficult to determine the individual roles of m1-m5 receptors in the brain. Identification of the mAChR subtypes in the brain has been accomplished using in situ hybridization to localize their mRNAs,24 or highly selective antibodies to directly localize the proteins 111 see also Van der Zee and Luiten.196 All subtypes appear to be present in the brain, although with different densities, localization and relative abundance (Table 1). In the forebrain, the region of interest for AD, the major mAChRs subtypes found are the m1, m2 and m4 proteins. For example, quantitative immunoprecipitation studies showed that in the hippocampus and several areas of human brain neocortex, the...

Controlled Release Microparticles

Plga Microparticles

Another interesting advantage of controlled release microparticles compared to larger implants is the possibility to inject them directly into inoperable tumors. Using standard needles anticancer drug-loaded systems can be administered by stereotaxy without causing major damage to the brain tissue. For instance, the group of Benoit and Menei developed 5-fluorouracil-loaded, PLGA-based microparticles that can be used for both the treatment of operable as well as inoperable malignant gliomas (62-66,70). Due to the significant progress in neurosurgery it is nowadays possible to precisely inject small volumes of microparticle suspensions at any position in the brain. Using a stereotaxic frame (or even frameless) computer-assisted neurosurgery (neuronavigation) can guide the implantation of electrodes, catheters, injections or the realization of biopsies (71). The morbidity of stereotaxic procedures is low (

Da Transporter And Cocaine Dependence 521 Regulation of the Dopamine Transporter DAT by Cocaine

Dopamine Dat Binding Dependence

Figure 5.1 Visualization of the distribution of the DA transporter, D3 receptor, and k2-opioid receptor in the human brain of a drug-free control subject and a representative cocaine overdose victim. (A, B) The DA transporter was measured using 3H WIN 35,428 (2 nM) as described previously. (C, D) The D3 receptor was measured using 3H -(+)-7-OH-DPAT (1 nm) in the presence of GTP (300 mm) to enhance the selective labeling of the D3 receptor subtype over the D2 receptor subtype as described previously. (E, F) The k2-opioid receptor subtype was measured using 125I IOXY on tissue sections pretreated with BIT and FIT to occlude binding to the and 8-opioid receptors, respectively. Figure 5.1 Visualization of the distribution of the DA transporter, D3 receptor, and k2-opioid receptor in the human brain of a drug-free control subject and a representative cocaine overdose victim. (A, B) The DA transporter was measured using 3H WIN 35,428 (2 nM) as described previously. (C, D) The D3 receptor...

Neurotoxicity Associated With Meth Consumption

Post-mortem human studies partially confirm preclinical findings in animals. METH abusers have decreased striatal tyrosine hydroxylase, DA, and DAT in the NAC and striatum.265 Yet presynaptic markers VMAT and DOPA decarboxylase are not altered.266 These findings suggest that there is no permanent damage to neurons in humans and confirms the results of one study in monkeys showing that nigral cell bodies are preserved following recovery.255 However, evidence from imaging studies indicate, no matter the length of time of recovery, deficits remain267 (see below). A number of factors, however, may explain these discrepant results between animal and post-mortem studies such as dose, duration of abuse, young vs. old population, and past drug histories. Taken together, post-mortem evidence supports that the human brain is susceptible to METH-induced alterations in DAergic parameters.

Effect Scaling and MDMA Dosing Regimens

Administration of MDMA at doses of 1 to 3 mg kg causes marked elevations in extracellular 5-HT and DA in rat brain, as determined by in vivo microdialysis.33 3439 Although it is impossible to directly measure 5-HT and DA release in living human brain, clinical studies indicate that subjective effects of MDMA (1.5 mg kg, p.o.) are antagonized by SSRIs, suggesting the involvement of transporter-mediated release of 5-HT.1106 Nash et al.43 showed that i.p. injections of 1 to 3 mg kg of MDMA stimulate prolactin and corticosterone secretion in rats, and similar oral doses increase plasma prolactin and cortisol in human drug users.1112 The dose of MDMA discriminated by rats and humans is identical 1.5 mg kg, i.p., for rats107 108 and 1.5 mg kg, p.o., for humans.109 Schenk et al.110 demonstrated that rats can be trained to self-administer MDMA using i.v. doses ranging from 0.25 to 1.0 mg kg, indicating these doses possess reinforcing efficacy. Tancer and Johanson111 reported that 1 and 2 mg...

Neuromancing With Neuroscience

The upshot of this methodological enterprise is that science is now able to speculate about normal brain function, and is able to link localised physical brain mechanisms with aspects of the mind. This is quite an achievement, resulting directly from the prevailing 'localisation' paradigm governing a major part of neuropsychology. It is therefore not unusual to come across references to the 'mapping' of the human brain, where different areas are associated with different psychological functions.

Refined Forms

Wholly synthetic drugs are made from scratch in the laboratory and do not occur naturally. Valium, PCP (phencyclidine), and secobarbital (Seconal are examples. It may be that synthetic drugs are the most dangerous of all and the hardest to form good relationships with, but it is risky to make such sweeping judgments. Very recently, researchers discovered Valium receptors in the human brain, making them think that the body must produce some internal analog to that completely synthetic tranquilizer. Did the chemists who created Valium in a laboratory just hit upon that molecule by chance Has Valium become so popular because its effect resembles that of an endogenous substance Or might Valium receptors have developed in the brain in response to use of the drug It is interesting to speculate on these questions, even though science may never be able to answer them.

Methods

ISHH is typically performed with either synthetic oligonucleotide (DNA normally 40 bases) or ribonucleotide (RNA normally 100-1000 bases) probes on freshly frozen brain tissue. The experimental procedures described in the following subheadings detail the methodology for ISHH using ribonucleotide probes (riboprobes), as such protocols normally result in higher hybridization signals with greater signal-to-noise ratio. Although the shorter oligonucleotide probes should have higher tissue penetrance than the riboprobes, the resulting hybridization signal is still much lower than with the riboprobe (see Fig. 1), most likely due to the higher amount of radiolabeled nucleotides per hybridized mRNA molecule obtained with the riboprobes. In addition, the high stability of the RNA-RNA (as compared to RNA-DNA and DNA-DNA) duplexes allow for increased stringency conditions (e.g., increased temperature and low salt concentration) to be used during the hybridization and post-hybridization washes...

Antisense

Whole hemisphere human brain cryosections can be cut even up to 100 im thick with good hybridization results (22). However, these large sections are not appropriate for discrete microscopic evaluation of the hybridization signal. 4. Superfrost and poly-l-lysine coated microscope slides are better than gelatin-subbed slides for very high stringency ISHH conditions (23). However, the gelatin-subbed slides can work perfectly well under normal hybridization conditions and is easily made in the laboratory (17). Poly-l-lysine-coated slides can also be prepared in the lab, but it has been more cost effective and more reliable to buy precleaned coated slides that are immediately ready for use. Both poly-l-lysine and Superfrost slides have proven very reliable, but Superfrost slides are also normally available in large sizes and thus very useful for processing the human brain sections that often require high stringency conditions (24).

Roger Gpertwee

The gene encoding the cannabinoid CB1 receptor was first cloned by Matsuda et al. (1990) from a rat cerebral cortex cDNA library using an oligonucleotide probe based on the sequence that encodes part of the bovine substance K receptor. Rat CB1 receptor cDNA proved to be 5.7 kilobases in length with a predicted 473 amirio acid product. Subsequently, human CB1 cDNA was isolated from human brain stem and testis cDNA libraries (G rard et al., 1990, 1991) and mouse CB1 cDNA from a C57BL 6 mouse brain cDNA library (Chakrabarti et al, 1995). These have predicted protein products of 472 and 473 amino acids respectively. The human CB1 gene has been genetically mapped to the q14-q15 region of chromosome 6 (Caenazzo et al., 1991 Hoehe et al., 1991) and the mouse CB1 gene to proximal chromosome 4, a location at which other homologues of human 6q genes occur (Stubbs et al., 1996 Onaivi et at., 1996a). The genomic location of the rat CB1 receptor has yet to be determined.

Summary

In summary, our current studies show that treatment with a bacterial endotoxin, lipopolysaccharide (LPS), induces the expression of mu opioid receptors in the rat mesentery. This induction may be mediated through IL-l's actions on mu opioid receptors. Morphine stimulates the expression of adhesion molecules in human brain microvascular endothelial cells (HBMEC) isolated from pathological tissues. Under pathological conditions, mu opioid receptor-dependent pathways may be modulated through the induction of mu opioid receptors, especially in endothelial cells. Treatment with morphine increases 14C -inulin permeability of an in vitro microvascular endothelial

Arachidonoylglycerol

2-AG was also detected in the peripheral nervous system. Huang et al. (1999) reported that 2-AG is present in the rat sciatic nerve, lumbar spinal cord, and lumbar dorsal root ganglion, and Di Marzo, Breivogel, et al. (2000) demonstrated the occurrence of 2-AG in the mouse spinal cord. 2-AG has also been shown to occur in the rat retina and bovine retina (Straiker et al., 1999 Bisogno, Delton-Vandenbroucke, et al., 1999). Several tumors of nervous system origin have also been shown to contain 2-AG Maccarrone, Attina, Cartoni, et al. (2001) reported that 2-AG was detected in the tumoral human brain (meningioma) and human neuroblastoma CHP100 cells.

Pathways

Most of the DA cell bodies (about 400 000) in the human brain are found in the A9 nucleus which forms the zona compacta (dorsal part) of the substantia nigra (SN), although a few cell bodies are found in the more ventral zona reticulata and in the zona lateralis as well (Fig. 7.1). A8 is lateral, caudal and somewhat dorsal to A9 and A10 whereas A10 is ventral to A9. Axons from A9 form the major contribution, together with some from A8, to the principal DA nigrostriatal pathway running to the striatum (caudate nucleus and putamen) and amygdala. This pathway is lateral to, but runs with, a more medial DA pathway, predominantly from A10, which innervates the nucleus accumbens and olfactory tubercle (mesolimbic pathway) as well as parts of the cortex (mesocortical system) such as the prefrontal and perirhinal cortex. The DA innervation to the anterior cingulate cortex also comes from A10 but with some axons from A9. There is in fact no clear divide between A9 and A10 and some overlap of...

Autoradiography

Miles Herkenham performed the first CB1 receptor distribution studies using au-toradiography with the tritiated CB1 agonist, CP55,940. Examples of his results from human brain are shown in Fig. 1. A striking feature of the autoradiographic studies was the extraordinarily high levels of CB1 receptors found in substantia nigra, globus pallidus, hippocampus, cerebellum, and cortex. The levels of CB1 receptors found in these brain regions in the rat approached 6 pmole mg (Herkenham et al. 1991). To give a sense of the magnitude of CB1 receptor expression, CB1 receptors are tenfold denser than D2 receptors in the basal ganglia and have a density similar to cortical ionotropic glutamate receptors. The specificity of these results was verified by Virginia Seybold and her colleagues, who performed a systematic autoradiographic study of rat brain using tritiated WIN55,212-2, a structurally distinct CB1 agonist (Jansen et al. 1992). These thorough studies in rodents have been complemented by...

Neocortex

CB1 receptors are densely expressed in all regions of the cortex (Herkenham et al. 1991 Mailleux and Vanderhaeghen 1992 Matsuda et al. 1993 Glass et al. 1997 Tsou et al. 1998a Egertova and Elphick 2000). The variation in CB1 expression across cortical regions has been examined most extensively in human brain using receptor autoradiography. Here there is variation between regions, with higher

Distribution

Tissues in which anandamide has been found are human, cow, sheep, pig and rat brain, human and rat spleen, human heart and rat skin and testis (Devane et al., 1992b Schmid et al., 1995 Felder et al., 1996 Sugiura et al., 1996c). The capacity to synthesize and or hydrolyse anandamide has also been observed in a range of tissues (Sections 7.2 and 7.4). Within the brain, anandamide has so far been detected in hippocampus, striatum, cerebellum and thalamus, its concentrations between areas (measured before the onset of any significant postmortem changes) varying more widely in human brain (25pmol g tissue in the cerebellum to 148pmol g tissue in the hippocampus) than in rat brain (20-29pmol g tissue) (Felder et al., 1996). Basal levels of anandamide in fresh tissue tend to be markedly less than those of other endogenous N-acylethanolamines. Thus Schmid et al. (1995) have found anandamide to make up only 0.9 of all N-acylethanolamines in fresh pig brain (173pmol anandamide g wet weight),...

Symbols In Formation

Such universality might be due to the fact that mythical symbols represent stable, organised concentrations of information produced by the most holistic integrative type of information processing achieved by the human brain. The symbol embodies a whole set of relations or, to be more specific, it is the point where a huge web of psychological relations converge. To fully understand the symbol is to sense at once all of its relations to other objects of perceptual experience. In other words, visual symbols play a role in a psychological language. (here, I again invoke the concept of language since language is essentially an informational system not restricted to words alone. Language, in the abstract way in which I refer to it, is a system of informational elements bearing definite relations with one another hence a language of words, of molecules, of symbols etc).

Natural Mind

United States government-funded studies at St. Louis Medical University in 1989 and th eU.S. government's National Institute of Mental Health in 1990 moved cannabis research into a new realm by confirming that the human brain has receptor sites for THC and its natural cannabis cousins to which no other compounds known thus far will bind.

Material

N,N-Dimethyltryptamine and 5-Methoxy-Dimethyltryptamine are naturally occurring psychedelics found in a variety of plants around the world, several of which are native to the Amazon region. These alkaloids, which are usually found together in the plants, are also found in the human brain as neurotransmitters, as well as m our blood, urine, and spinal fluid 1 . DMT is produced in the human pineal gland which is correlated to the 3rd eye or Ajna Chakra in the Indian spiritual system. Meditative states attained by yogis who concentrate on the 3rd eye may be the result of increased DMT levels. DMT is produced in heavy concentration in the glands of some tropical toads, such as Bufo Alvarius. Some people actually make a practice of squeezing out this venom, then drying and smoking it to get high.

Opioid receptors

The peptides endomorphin 1 and 2 have been identified in human brain and show selectivity and affinity for m receptors. In mice, endomorphin 1 and 2 produce spinal and supraspinal analgesia. They appear to act through regulation of calcium entry into the target cell via voltage-gated channels and also to inhibit cyclic AMP production in m receptor bearing cells. Clinically they mimic the action of other m opioids. Their clinical relevance and unique adverse effects profiles await further investigation. Similarly the clinical usefulness of newly discovered receptor systems, such as the orphan opioid receptor for nociceptin (ORL1), which produces analgesia, hyperalge-sia, and anti-opioid effects in animals, has yet to be defined.

And So On

(Read the 1982 N.I.H. the National Academy of Science's evaluation on past studies and the Costa Rica report, 1980.) No Harm to Human Brain or Intelligence Hemp has been used in virtually all societies since time immemorial as a work motivator and to highlight and renew creative energies.

Cancer Stem Cells

Researchers have also identified cells with stem cell-like properties in children's brain tumors. Initially, it was discovered that the protein CD133 is displayed on the surface of stem cells in healthy human brain tissue. This allowed separation of brain tumor samples into populations based on their surface proteins, and led to the identification of a small population (found in a variety of brain tumors) expressing CD133. These cells were grown in vitro and had the remarkable ability to differentiate into the same types of brain cells as found in the original tumor. Other tumor cells (i.e., non-stem cells) from the same tumor eventually stopped growing. Interestingly, CD133-expressing cells isolated from pediatric brain tumors have been

Tenderness

Let's just put all this down to good old history. Let's just say it was an evolutionary plus point for men to be violent and aggressive, after all, the human brain was only in its infancy, and we had to fend off predators and other males who had designs on our women folk. We had more muscle than the women, whose task it was to give birth to and rear offspring, so we took up the task of protecting our family, and were prepared to use whatever force necessary to do it.

Neuropsychiatric

The human brain contains numerous cannabinoid receptors which may in part account for the many neuropsychiatric effects of marijuana (Hubbard et al., 1999). Some common neuropsychiatric side effects of marijuana include paranoia, anxiety, dysphoria, aggressiveness, hallucinations, changes in libido, dereal-ization, depersonalization, altered time perception, worsened short-term memory, altered motivation, possible increased suicidal ideation (Hubbard et al., 1999 Smart and Adlaf, 1982 Ashton, 1999 Nahas and Latour, 1992 Schuckit, 1989 Hollister, 1988 Hubbard etal., 1993 Gottschalk et al., 1977 Nahas, 1977 Weil, 1970 Tunving, 1985). Most of the acute adverse neuropsychiatric effects appear to be anxiety reactions (Tunving, 1985). Sedation often occurs after the initial feeling of intoxication (Ashton, 1999).

Cannabis Markianos

Biegon, A. and Kerman, I. (1995) Quantitative autoradiography of cannabinoid receptors in the human brain post-mortem, in Sites of Drug Action in the Human Brain, edited by A. Biegon and N. D. Volkow, pp. 65-74. Boca Raton CRC Press. Glass, M., Dragunow, M. and Faull, R. L. (1997) Cannabinoid receptors in the human brain A detailed anatomical and quantitative autoradiographic study in the fetal, neonatal and adult human brain, Neuroscience 77 299-318. Westlake, T. M., Howlett, A. C., Bonner, T. I., Matsuda, L. A. and Herkenham, M. (1994) Cannabinoid receptor binding and messenger RNA expression in human brain An in vitro receptor autoradiography and in situ hybridization histochemistry study of normal aged and Alzheimer's brains, Neuroscience 63 637-652.

Human Research

There is no evidence from human studies of any structural brain damage following prolonged exposure to cannabinoids. The most recent study using sophisticated technology and measurement techniques showed that frequent but relatively short-term use of marijuana does not produce any structural brain abnormalities or global or regional changes in brain tissue volume or composition assessable by magnetic resonance imaging (MRI) (Block et al., 2000a). Existing methods of brain imaging may not be sensitive enough to detect the long-term subcellular or biochemical alterations that might be produced in the CNS in the absence of any distortion of gross cell architecture. The most convincing evidence on brain alterations would come from post-mortem studies. Recent studies of human brain postmortem have reported reduced binding and decreased cannabinoid receptor density with disease and normal aging, but no studies have yet examined the brains of healthy long-term users of marijuana. Westlake et...

Concluding Remarks

Chen, Y., McCarron, R.M., Ohara, Y., Bembry, J., Azzam, N., Lenz, F.A., Shohami, E., Mechoulam, R., and Spatz, M. (2000) Human brain capillary endothelium 2-arachidonoglycerol (endocannabinoid) interacts with endothelin-1, Circulation Research 87 323-327. Maccarrone, M., Attina, M., Cartoni, A., Bari, M., and Finazzi-Agro, A. (2001) Gas chromatography-mass spectrometry analysis of endogenous cannabinoids in healthy and tumoral human brain and human cells in culture, Journal of Neurochemistry 76 594-601.

Subtypes

Nicotinic acetylcholine receptors are ligand-gated ion channels. This receptor is composed of five polypeptide subunits that form a barrel-like structure around a central ion channel.21 In contrast to nAChRs located in the periphery which are composed of al, (31, 6, e, Y subunits, the standard configuration of the neuronal nAChRs include combinations of a and ( sub-units. However, a7, a8, and a9 subunits can also form functional nAChRs that consist of a single subunit type.25 Presently, the subunits a2-a7 and (2-(4 have been identified in the human brain and the distribution of these subunits in the human brain are presently being examined (see ref. 71 for a review of the nAChRs in the human brain). As in other receptor systems, much more work has examined the distribution of nAChR subunits in the rodent brain. In rodent models, the a3, a7, (2 subunits, and to a lesser extent the a4 subunit are expressed in the hippocampus (see ref. 73). The a2, a4, a5, a7, (2, and (4 subunits have...

Receptors

An autoradiographic study showed that K-opioid receptors are present in greatest abundance in the pyramidal and granule cell layers and areas adjacent to these layers, as well as in CA3 stratum lucidum in the rat.24 K-Opioid receptor specific antibodies revealed additional receptors in the inner molecular layer of pyramidal cells in guinea pigs10 and in the middle molecular layer of the ventral dentate gyrus in rats.23 It is interesting to note that the pattern of K-opioid receptor expression in guinea pigs, as opposed to rats, resembles the pattern seen in the human brain.27

Inactivation

One drug that seems to cause quite marked, long-term changes in 5-HT transporter function is MDMA. Single-photon emission-computed tomography (SPECT) which provides an image of the binding of (S-CIT) to the transporters in the (living) human brain shows that this is greatly reduced (and, in some cases, totally absent) in subjects who claim to use MDMA (Semple et al. 1999). Interestingly, fenfluramine, another 5-HT-releasing agent, does not seem to have this effect. It has been suggested that loss of transporters in users of MDMA is due to the death of 5-HT neurons and that this is evidence for its neurotoxic effects. This toxicity is thought to be mediated by the formation of quinones and then free radicals from the metabolites of MDMA, although there are alternative explanations (see Sprague, Everman and Nichols 1998) and some individuals still dispute that this drug is actually neurotoxic in humans. At the very least, there is accumulating evidence for long-term deficits in...

Naturally gay

Versy on that study comes not just from advocacy groups, but from the scientific community, as it has not been confirmed and was done post mortem, so the full sexual history of the individuals is not known. However, an attempt to replicate the 1991 human results showed a statistical trend that this brain region was smaller in homosexual men, but did not find a statistically significant difference in the number of cells in this region. Also, the size difference did not quite reach the level of statistical significance. Those researchers urged people not to rush to judgment in either direction until more studies are done. It is, however, now accepted that the difference in size for this region does exist between men and women. The male sheep results seem to indicate that there might be some correlation between sexual orientation and brain anatomy.

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