By I. Kapotth. Seattle Pacific University.
Lesion segmentation and and matching in magnetic resonance imaging buy discount mentat 60caps online. Visualization in manual warping to a reference brain: intra- and interobserver Biomedical Computing 1994 buy discount mentat 60 caps. Neuroim- II: Inflation, flattening, and a surface-based coordinate system. Quantitative 24: Automated 3D Analysis of Large Brain MRI Databases 313 in vivo measurement of gyrification in the human brain: changes intensity nonuniformity correction methods for MRI. A non-parametric method parcellation of human cerebral white matter and nuclei ii. A probabilistic built 3d morphometric brain atlas: study of cerebral ventricle ribbon model for shape analysis of the cerebral sulci: application shape. J Comput Assist Tomogr 1998;22(6): tional Conference, VBC 1996 Proceedings. Digital brain atlases brain: 3-dimensional proportional system: an approach to cerebral [letter]. Stat Methods Med Res 1997;6(3): correcting for variable cortical morphology in functional imaging 267–299. IEEE International Conference on Ro- mesh algorithms for creating a probabilistic 3d surface atlas of botics and Automation Symposia Proceedings (Cat. A voxel-based mor- ing three-dimensional images of the brain. IEEE Trans Med Imag- phometry study of semantic dementia: relationship between tem- ing 1996;15(4):402–417. Corpus callosum shape and and surface anatomy using magnetic resonance imaging. Psychia- size in male patients with schizophrenia [see comments]. Finding parametric representations of gray matter in patients with schizophrenia and healthy control the cortical sulci using an active contour model. J Neuropsychiatry Clin Neurosci 1998; 1997;1(4):295–315. Stutt- of human cerebral cortex using a surface-based atlas. Functional and struc- paracingulate sulci: pattern, variability, asymmetry, and probabi- tural mapping of human cerebral cortex: solutions are in the listic map. Cerebellar mor- neural pathway in children and adolescents. Science 1999;283: phology as a predictor of symptom and psychosocial outcome in 1908–1911. Quantifying variability in anatomical differences in human primary auditory cortex: proba- the planum temporale: a probability map. Cerebral Cortex 1999; bilistic mapping and volume measurement from MR scans. Volumetry of hippocampus statistical analysis for CBF activation studies in human brain. J and amygdala with high-resolution MRI and three-dimensional Cereb Blood Flow Metab 1992;12:900–918. A voxel-based method longitudinal magnetic resonance imaging study. Arch Gen Psy- for the statistical analysis of gray and white matter density applied chiatry 1999;56(7):649–654. Automatic quantification struction of the human central sulcus reveals a morphological of multiple sclerosis lesion volume using stereotaxic space. Proceedings of the 4th International Conference on Visualization in 66. A comparison of retrospective Biomedical Computing, VBC 1996. SHULMAN In the last 5 years there has been a renewed interest in the tory and excitatory neuronal function requiring energy. Ob- role of metabolism in supporting brain function. Much of servation of a regional increase or decrease of the functional this interest is based on the development of functional posi- imaging signal is not sufficient to distinguish these possibili- tron emission tomography (PET) and magnetic resonance ties. Glia also requires energy, and the relationship between imaging (MRI). Although often incorrectly described as di- its energy demands and neuronal activity remains to be es- rectly mapping neuronal activity, both functional PET and tablished. Given these uncertainties about the meaning of MRI actually measure changes in either glucose metabolism the signal at a neuronal level, the validity of functional imag- or physiologic parameters coupled to glucose metabolism ing as a tool for studying mental processes has been largely such as blood flow and volume (1). A major limitation in established based on agreement with prior expectation from interpreting functional imaging is that the relationship be- psychological paradigms (3,5). It differs by allowing the measurement of the concen- cesses are involved in short-term neuronal information trations and synthesis rates of individual chemical com- transfer, and the relative distribution of energy among them pounds within precisely defined regions in the brain. There is also uncertainty as to basis of its chemical specificity is that the resonance fre- how the different classes of neurons in a region contribute quency of an MRS active nucleus depends not only on the to the overall energy consumption. While an increase in the local magnetic field strength, but also on its chemical envi- imaging signal is usually assigned to an increase in neuronal ronment, a phenomenon referred to as chemical shift. MRS measurements of the 1H nucleus are the most commonly excitation, this interpretation is confounded by both inhibi- used for in vivo studies due to 1H being the most sensitive nucleus present in biological systems. Metabolites that can be measured by 1H MRS include aspartate, -aminobutyric Douglas L. Shulman: Yale University School acid (GABA), glucose, glutamate, glutamine, and lactate.
Ideally purchase 60 caps mentat, every text should be read by two qualified colleagues with a good sense of literary style buy mentat 60 caps overnight delivery. After being read twice, the text should be returned to the author with any unanswered questions. The corrections of the authors must be recorded using the function “track changes” (click Tools->track changes ->highlight changes + highlight changes while editing). Microsoft Word spell verification Word spell check is a valuable tool and should be used by the authors, the readers and the proofreaders. As soon as the dialog window opens, check that the window shows correctly “Spelling < your mother tongue >”. This is the procedure if a different language is given: mark the whole text with CTRL-A, then define the language: Tools->Language->Set Language + your mother tongue + OK) When you subject the text to spell verification, words which are unknown to the system are shown in red. If the spelling is correct, type ALT-A in order to add the word to the supplementary dictionary. The final version of the texts The individual chapters gradually pass though the stages of reading and final proofreading and assume their definitive form. You are on the verge of publishing the first chapters on the internet and the authors are waiting impatiently to see themselves on the net. Suddenly, a potential sponsor calls and asks to talk. Behind the scenes Negotiations with sponsors Foundations and pharmaceutical companies can be considered as possible sponsors for your project. Foundations will generally subsidise your project, while pharmaceutical companies will buy up part of the printed version in order to distribute the books to interested doctors. As every type of co-operation between doctors and pharmaceutical companies must remain free of any conflict of interests, there are a few rules you should know. Leprosy When you wrote, you wrote the truth and did not formulate your texts with company X or company Y in mind. The standards regarding independence of statements and recommended therapies cannot be set high enough. Any doctor who writes something against his own convictions for his own benefit is guilty. Doctors who practise accommodating journalism quickly end up on a par with drug barons and arms dealers. May anyone who practises this kind of accommodating journalism in medicine be struck down by leprosy so that he can no longer write! Selection of potential sponsors The chances of reaching an agreement with sponsors from the pharmaceutical industry depend on various factors. Both personal and internal company factors play a role here. One of the golden rules of a colleague who had 30 years experience with the publication of medical textbooks was: “The marketing budgets of pharmaceutical companies are structured according to drugs. Budgets are generous when new drugs are being introduced to the market, very generous when a drug is being introduced and has to compete against an existing market leader. This is not meant in a derogatory way, it just means that you should ask yourself these questions before you approach the company: 1. What can I offer this company with my book and/or my website that other media cannot? What is allowed and what is not Pharmaceutical companies live off the sale of their drugs, and the staff of their marketing departments have been instructed to increase the turnover of these drugs. The companies want to sell, pulling out all the stops: that is their job. It is our job to distil the truth from the information available to us, especially from scientific literature. Regardless of the fact that you have a duty to write the truth and nothing but the truth, you should remember the following points when negotiating with possible sponsors: It is allowed for the potential sponsor to itemise the advantages of his product. Upon this request, you should send him the passages as a PDF file, never as a Word document. It is not allowed to provide the sponsor with the original document so that he can make corrections to it. It is bad to print the logo of your sponsor on the cover. It is dubious practice to accept advertising for drugs in the book, such as full page adverts on the last few pages. Behind the scenes If a potential sponsor does not accept these points, you must abstain from any further co-operation – even if this causes temporary difficulties with the financing of your project. Remember: the worst thing that can happen to you is loss of credibility. Everyone knows the jokes about the qualified university lecturers working as pharmaceutical sales reps. If you sell yourself you lose your credibility – a flaw which marks some people in our profession for the rest of their lives. Summary Editor/Publisher If you want to pay your co-authors a fee of 25 Euro per page, you have to sell more than 1,000 books. A logo entry on a good website can be worth several thousand Euro a year. Author Would you have believed that there is so much activity behind the scenes while you are preparing your chapter? Doctor Go on, admit it: after reading this chapter, you almost feel like writing yourself. But please remember what we said at the beginning: clinical textbooks are written in large editorial teams. If you are itching to write, try to gain access to an existing or developing team of authors. Student Try to become involved in Flying Publisher projects. You will learn a lot – how book projects are financed, how a publishing 56 Negotiations with sponsors house is registered, and how websites are maintained. Maybe the publishers will even let you in on the secrets of negotiating with sponsors one day.
Although afferents from the amygdala infragranular layers (layers 5 and 6) (74) cheap mentat 60caps without prescription, and approximately project more densely to orbital than dorsal regions of the 15% to 20% of neurons projecting to the striatum are lo- PFC order mentat 60 caps line, these tend to terminate in layers 1 and 6 (83). In addition, the nature of the cortical Subcortical nuclei containing monoamines or acetylcho- output to a given region may vary with the location of the line also exhibit distinct laminar patterns of termination in cell body of origin. For example, neurons in layer 6 provide the PFC, along with substantial regional differences in rela- 'modulatory' inputs to cells in higher order thalamic nuclei (such as the mediodorsal thalamic nucleus, the principal source of thalamic projections to the dPFC) as well as inputs to the thalamic reticular nucleus, which regulates thalamo- cortical interactions. In contrast, thalamic projections origi- nating in layer 5 do not innervate the reticular nucleus and appear to provide 'driving' afferent inputs to higher order nuclei (77). The innervation patterns of the intrinsic axon collaterals of pyramidal cells also tend to differ across cortical layers (71). Pyramidal neurons in layers 2 and 3 furnish local col- laterals that arborize in the vicinity of the cell body, as well as horizontal axon projections that spread for considerable distances through the gray matter and then give rise to dis- crete clusters of axon terminals in the supragranular layers. Although pyramidal neurons in layers 5 and 6 also furnish horizontal intrinsic collaterals, these have a more limited FIGURE53. Schematic diagramof principalcorticocortical con- spread and do not terminate in spatially segregated clusters. Double-head arrows indicate that most connections are reciprocal. Relatively sparse direct connections between dor- interlaminar connections. The intrinsic axonal connections solateral prefrontal cortex and limbic structures (hippocampal of pyramidal neurons in layers 2 and 3 of the dPFC also formation and amygdala nuclei) are depicted with a dashed line. In: Miller BL, Cum- in at least some other cortical regions. Chapter 53: Neural Circuitry and the Pathophysiology of Schizophrenia 735 tive density. Dopamine (DA)-containing axons from the not appear to be reduced (35,95), although less rigorous ventral mesencephalon have a bilaminar distribution in the methods were employed in these studies. PFC (84), forming a dense band in layers 1 through the In summary, although a reduction in neuron number most superficial portion of layer 3 and a second band of cannot be completely excluded, the subtle reduction in lower density in layers deep 5 and 6. In more densely inner- dPFC gray matter in schizophrenia may be attributable to vated regions, such as dorsomedial PFC (area 9), labeled a combination of smaller neurons and a decrease in dPFC axons are also present in high density in the middle cortical neuropil, the axon terminals, distal dendrites and dendritic layers, forming a third distinctive band in deep layer 3. The spines that represent the principal components of cortical noradrenergic (NA) projection from the locus coeruleus ex- synapses. Indeed, as described in more detail below, these hibits a different, and in some ways complementary, laminar two factors may be interrelated. The den- sity of NA axons is substantially greater in the deep cortical Candidate Sources for Synaptic layers, especially layer 5, than in the more superficial cortical Reductions laminae. In particular, few NA axons are present in layer 1, which receives a dense DA innervation. In contrast, the The apparent reduction in synaptic connectivity in the relatively uniform laminar distribution of cholinergic (87) dPFC of subjects with schizophrenia may be attributable and serotonergic (88) axons contrasts with the substantial to one or more of the following sources of synapses: axon heterogeneity exhibited by both DA and NA axons. Although none of these sources can be excluded at present, INTEGRITY OF PREFRONTAL CORTICAL some are more likely to be major contributors than others. CIRCUITRY IN SCHIZOPHRENIA For example, one subcortical source, the DA projections from the mesencephalon, may be reduced in number in In this section, we consider how this knowledge about the schizophrenia as evidenced by the report of diminished den- normal organization of dPFC circuitry can be used to inter- sities of axons immunoreactive for tyrosine hydroxylase, the pret studies of the integrity of different types of neural ele- rate limiting enzyme in catecholamine synthesis, and the ments in subjects with schizophrenia. As noted, several lines DA membrane transporter in the dPFC (96). However, of evidence support the hypothesis that schizophrenia is these reductions appeared to be restricted to the deep corti- associated with a decrease in the synaptic connectivity of cal layers. Furthermore, an in vivo neuroimaging study the dPFC. However, these abnormalities do not appear to found a reduced density of DA D1 receptors in the dPFC be a consequence of a decreased complement of dPFC neu- of subjects with schizophrenia (97); however, DA axons are rons, because several postmortem studies (34,37,89) have estimated to contribute less than 1% of cortical synapses reported either a normal or increased cell packing density (84). Consequently, even the complete loss of DA projec- in the dPFC. In addition, the one study that used unbiased tions to the dPFC could not, in isolation, account for the approaches to determine the total number of PFC neurons observed reductions in gray matter volume or synaptophysin did not observe a reduction in subjects with schizophrenia protein levels. The relatively small contributions that (90); however, the approaches used in these studies probably NA-, serotonin-, and acetylcholine-containing axons make lacked adequate sensitivity to detect reduced numbers of to the total number of synapses in the dPFC also argues small subpopulations of PFC neurons. Some studies that against disturbances in these systems as the principal cause focused on certain neuronal subpopulations have reported of reduced synaptic connectivity in this brain region. However, the latter abnormality was not observed in reduced somal volume in subjects with schizophrenia (89, another study (35), and it should be noted that a reduction 93) may suggest that the synapses furnished by the intrinsic in neuronal density when using immunocytochemical axon collaterals of these neurons are reduced in number, markers might reflect an alteration in the target protein because somal volume tends to be correlated with the size rather than in the number of cells. Evidence for a distur- Smaller neuronal cell bodies could also contribute to the bance in intrinsic connectivity is supported by recent studies observed reduction in PFC gray matter in schizophrenia. Among 250 functional gene groups, the most marked decreased in subjects with schizophrenia (89,93). In addi- changes in expression were present in the group of genes that tion, this reduction in somal volume may be associated with encode for proteins involved in the regulation of presynaptic a decrease in total length of the basilar dendrites of these neurotransmitter release. In contrast, the size of GABA neurons does indicate a general impairment in the efficacy of synaptic 736 Neuropsychopharmacology: The Fifth Generation of Progress transmission within the dPFC in schizophrenia, whether PFC, and, given the dependence of working memory tasks they represent a 'primary' abnormality intrinsic to the on the integrity of thalamo–prefrontal connections (29), to dPFC or a 'secondary' response to altered afferent drive the disturbances in working memory observed in schizo- to this brain region remains to be determined. However, in contrast to other species, the primate because the specific genes in this group that were most al- MDN contains both cortically projecting neurons and local tered appeared to differ across subjects, it seems unlikely circuit neurons. Thus, it is critical to determine which sub- that these findings can be explained solely by reduction in population(s) of MDN neurons are affected in schizophre- the number of intrinsic dPFC synapses. Interestingly, the density of neurons in the anterior this view, the expression of synaptophysin mRNA does not thalamic nuclei that contain parvalbumin (113), a calcium- appear to be reduced in the dPFC of subjects with schizo- binding protein present in thalamic projection neurons phrenia (50,100), suggesting that the reduction in this syn- (114), is reduced in schizophrenia; however, whether this aptic protein marker in the dPFC may have an extrinsic reduction represents an actual loss of neurons, as opposed source. Consistent with this interpretation, synaptophysin to an activity-dependent decrease in parvalbumin expres- mRNA levels are reduced in cortical areas that do furnish sion, is not known. However, whether these Within the dPFC, five other lines of evidence are also transcriptional changes are present in PFC-projecting neu- consistent with a reduction in inputs from the MDN (Fig. First, a preliminary report notes that subjects with synaptophysin protein in the terminal fields of these neu- schizophrenia, but not those with major depression, have a rons, have not been assessed. For example, some structural MRI studies have revealed a In contrast, parvalbumin-labeled varicosities were not de- reduction in thalamic volume in subjects with schizophrenia creased in layers 2 to superficial 3, suggesting that the reduc- (103–106). In addition, thalamic volume was correlated tion in layers deep 3 and 4 might not be attributable to with prefrontal white matter volume in schizophrenic sub- changes in the axon terminals of the parvalbumin-contain- jects (107), suggesting that a reduction in thalamic volume ing subset of cortical GABA neurons present in cortical was associated with fewer axonal projections to the PFC.
Decreased striatal dopaminergic responsive- meeting of the Committee on Problems of Drug Dependence buy generic mentat 60 caps line, Key- ness in detoxified cocaine abusers discount mentat 60caps amex. Drug addiction: the yin and yang of hedonic homeo- cingulate cortex to behaviour. Curr Opin Neurobiol Symposium on brain imaging in substance abuse, 56th annual 1996;6:243–251. Blockade of striatal dopamine transporters West Palm Beach, FL, 1994. Regional brain blood flow during induced reports of 'high. Soc Neurosci Abstr 1996;22: their pharmacokinetics and distribution in the human brain. Euphorigenic doses of cocaine reduce ( I) - cocaine addiction. CIT SPECT measures of dopamine transporter availability in 83. Activation of memory circuits during cue-elicited human cocaine addicts. PET study of competition between intrave- cal specificity for drug-users and drug stimuli. Am J Psychiatry nous cocaine and C-11 raclopride at dopamine receptors in human subjects. Regional brain metabolic activation during tion in human brain. Functional MRI of human brain activation JAMA 1998;279:376–380. Acute effects of cocaine on human brain on Problems of Drug Dependence, Nashville, TN, 1996. A neural substrate of pre- in cocaine abusers: implications in addiction. Addiction, a disease of compulsion Y Acad Sci 1992;654:171–191. Activation of the hippocampus in normal hu- duced high and dopamine transporter occupancy. Proc Natl mans: a functional anatomical study of memory. Selective inhibition of cocaine-seeking behaviour dysfunction in drug abuse: implications for the control of behav- by a partial D3 dopamine receptor agonist. Emotion, decision-making the reinforcing effects of cocaine in rats. Dissociable cognitive deficits in the decision- self-administration: demonstration using a discrete trials proce- making cognition of chronic amphetamine abusers, opiate dure. Baclofen as a cocaine-anti- tryptophan-depleted normal volunteers: evidence for monoami- craving medication: a preliminary clinical study. Choosing between small, likely rewards and during cue-induced cocaine craving. Soc Neurosci Abstr 1999; large, unlikely rewards activates inferior and orbital prefrontal 25:815(abst No. Activation of reward circuitry in human opiate 1994;15:374–379. FOWLER Brain imaging can be used to assess the following in the ters. Both types of isotopes can be used to label ligands for human brain: (a) morphology [computed tomography (CT) specific receptor, transporter, or enzymatic systems to be and magnetic resonance imaging (MRI)];(b) electrical and used with PET or SPECT to quantify these parameters in living human brains. In addition, PET tracers such as [18F] magnetic signals [electroencephalography (EEG) and mag- or [11C]-labeled deoxyglucose (FDG, CDG) and [15O]-la- netoencephalography (MEG)];(c) neurotransmission [posi- tron emission tomography (PET) and single photon emis- beled water can be used to measure regional brain glucose sion computed tomography (SPECT)];(d) tissue metabolism and cerebral blood flow (CBF), and SPECT tracers such as 99mTc hexamethylpropyleneamineoxime composition [magnetic resonance spectroscopy (MRS)]; and (e) blood flow and metabolism [functional MRI (HMPAO) can be used to measure CBF. This information can be used to obtain images that reflect This chapter focuses mainly on the application of PET, brain structure, brain function, or chemical composition. SPECT, and MRI for the investigation of the effects of Information on structure in the brain can be obtained on drugs of abuse in the human brain and their relationship the basis of differences in chemical composition between with their reinforcing, addictive, and toxic effects. For structural brain imaging, this is description of these imaging techniques follows. Information on detect and measure the spatial distribution and movement brain function is derived from the differences in magnetic of radioisotopes in tissues of living subjects. PET measures properties of oxygenated versus deoxygenated hemoglobin compounds labeled with positron emitting radioisotopes (blood oxygenation-dependent or BOLD contrast). During and SPECT with single photon emitting radioisotopes. An activation of a brain region, an excess of arterial blood is advantage of the positron emitters is that some of these are delivered into the area, with concomitant changes in the isotopes for the natural elements of life (11C, 15O, 13N), and ratio of deoxyhemoglobin to oxyhemoglobin. Concentra- this feature enables labeling of compounds without affecting tion on a wide variety of compounds that reflect metabolic their pharmacologic properties. Although labeling an or- state of the tissue and cell integrity can be obtained with ganic compound with a single photon emitter such as 123I MRS. MRS can also be used to measure the concentration and metabolism of compounds such as 13C-glucose. The positron emitters used for which can be done using imaging modalities that measure imaging have shorter half-lives than the single photon emit- electrical activity, CBF, or brain metabolism. Of the modali- ties used for functional imaging, fMRI has the highest spa- tial resolution. Conversely, MEG and EEG are the imaging technologies with the highest temporal resolution, which Nora D. Volkow: Medical Department, Brookhaven National Labora- enables the examiner to assess the temporal displacement tory, Upton, New York. Fowler: Chemistry Department, Brookhaven National Labora- of activation signals as they propagate in brain on the order tory, Upton, New York. IMAGING MODALITIES USED TO INVESTIGATE THE LIVING HUMAN BRAINa Parameter Temporal Spatial Measured Resolution Resolution Sensitivity MEG Function 1 ms 5 mm EEG 1 ms 10–15 mm CT Structure ms MRI Structure ms 1. Research instruments have been developed that have better performance.