Single Photon Emission Tomography and Positron Emission Tomography

Another principle employed to obtain information about events within the living brain is to introduce specific compounds labelled with radioactive isotopes into the brain. The signals emitted from these radioactively labelled compounds reflect the dynamic distribution of the compounds in the brain. This is the principle of emission tomography. By selecting compounds that participate in brain functions without fundamentally altering them, kinetic information about the fate of the compound may be...

Specific Brain Imaging Methods Computed Tomography

X-rays were discovered by Wilhelm Conrad Rontgen in 1899. For this he was awarded the Nobel Prize in 1901. The high energy of X-rays makes them penetrate most biological tissues as a function of the electron density or the chemical composition of the tissue. Some tissues with a high calcium content (e.g. bone) have a high X-ray absorbing capacity (attenuation) soft tissues (e.g. brain) produce little attenuation. Accordingly, the conventional skull X-ray gives a distinct image of the bone...

Schizophrenia

The most frequently reported findings from qEEG studies in subjects with schizophrenia include an increase of slow (delta and theta) and fast (beta) activities, and a decrease in alpha power 68-79 . This pattern was initially attributed to the effects of neuroleptic treatment, since some drugs may induce a general slowing of EEG activity. However, this explanation has been ruled out by studies showing that slow wave activity is even more pronounced in untreated patients 74 , and it is also...

Adoption Studies

For many, adoption studies offer a more convincing separation of the effects of genes and environment than do twin studies and, as we have already noted, adoption studies had an important role historically in turning the tide towards a more biological view of schizophrenia. However, because of the difficulties in carrying out adoption studies, they have been used much less than twin studies in investigating the genetics of behaviour. There are three principal designs, all of which have been...

Advances and Insights from Convergent Functional Genomic Studies

The initial description and application of the concept of convergent functional genomics was in identifying genes involved in mania and psychotic mania 5 . Methamphetamine treatment of rats as an animal model for psychotic mania was used. Specific brain regions PFC, amygdala were analysed comprehensively for changes in gene expression using oligonucleo-tide GeneChip microarrays. These regions had been implicated in mood and psychotic disorders by previous studies in animal models and imaging...

Magnetic Resonance Imaging

The word magnetism comes from the name of the city Magnesia in Turkey, where many naturally occurring magnets can be found. The first physical principles for magnetism were formulated by Karl Friedrich Gauss in the eighteenth century. James Clerk Maxwell discovered the fundamental laws of electromagnetism in the following century. Felix Bloch 11 and Edward Mills Purcell et al. 12 independently discovered the nuclear magnetic resonance (NMR) phenomenon and were jointly awarded the Nobel Prize...

References

Plomin R., DeFries J., McClearn G., McGuffin P. (2001) Behavioral Genetics, 4th ed., Freeman, San Francisco. 2. Cardno A., McGuffin P. (1999) Psychiatric genetics. In A Century of Psychiatry, Vol. 2 (Ed. H. Freeman), pp. 343-347, Mosby-Wolfe Medical Communications, London. 3. Farmer A.E., McGuffin P. (1999) Ethics and psychiatric genetics. Psychiatric Ethics, 3rd ed. (Ed. S. Bloch), pp. 479-493, Oxford University Press, New York. 4. Shields J., Gottesman I.I. (1971) Man, Mind and Heredity...

HPA Axis Abnormalities in Depression

The occurrence of depression and other psychiatric symptoms in both Cushing's and Addison's disease served as an impetus for researchers to scrutinize HPA axis abnormalities in depression and other psychiatric disorders. Most investigators would agree that one of the most venerable findings in all of psychiatry is the hyperactivity of the HPA axis observed in a significant subset of patients with major depression. Based on the work of research groups led by Board, Bunney and Hamburg, as well as...

Schizophrenia And Other Cognitive Disorders

Clinical Comorbidity Underlined by Overlapping Biological Mechanisms Disorders of cognition have traditionally been classified into psychoses and dementias. Other disorders of cognition include delirium and amnestic disorders. Psychoses were deemed to occur at an earlier age, to be biochemical genetic in nature and to be at least partially reversible pharmacologically. Dementias were deemed to occur at a more advanced age, be degenerative in nature and to be mostly irreversible. The...

Conclusions

When the psychiatrist Hans Berger discovered the EEG, he was hopeful of depicting physiological and pathological mental processes. In his diary he wrote more than 70 years ago May I succeed in finding a sort of mirror of brain function the elektrenkephalogram''. During the intervening period, the techniques for recording and, especially, analysing brain electrical activity have undergone constant progress, such that clinicians and researchers can now assess brain function with unique time...

Info

Alper K., G nther W., Pritchep L.S., John E.R., Brodie J. (1998) Correlation of qEEG with PET in schizophrenia. Neuropsychobiology, 38 50-56. 119. Guenther W., Davous P., Godet J.-L., Guillibert E., Breitling D., Rondot P. (1988) Bilateral brain dysfunction during motor activation in type II schizophrenia measured by EEG mapping. Biol. Psychiatry, 23 295-311. 120. Crow T.J. (1980) Molecular pathology of schizophrenia more than one disease process Br. Med. J., 280 66-68. 121. Morihisa J.M....

Functional Magnetic Resonance Imaging

During the past decade, another important application of MRI has emerged, functional magnetic resonance imaging (fMRI). This technique has been applied to a number of important questions with regard to brain function. Two independent phenomena have made the development of fMRI possible. The first is the principle of neurovascular coupling, i.e. the fact that when neuronal activity is increased in a brain region, it is followed by a local increase in blood flow through the region. When the...

Disorders of the HPT Axis

Disorders of the HPT axis lead to numerous psychiatric manifestations, ranging from mild depression to overt psychosis. Numerous conditions can lead to hypothyroid states, also known as myxoedema, including CNS causes of decreased TSH or TRH secretion, severe iodine deficiency, thyroid surgery, drugs, or autoimmune disorders. The most common cause of hypothyroidism is Hashimoto's thyroiditis, which is due to autoimmune destruction of thyroid tissue. Regardless of the aetiology, hypothyroidism...

Pituitarygrowth Hormone Axis

Growth hormone (GH) is synthesized and secreted from somatotrophs located in the anterior pituitary. Its release is unique in that it is controlled by two peptide hypothalamic hypophysiotropic hormones, growth hormone-releasing factor (GHRF) and somatostatin (SRIF). SRIF, also known as growth hormone-release-inhibiting hormone (GHIH), was first isolated from ovine hypothalamus in 1974. It is a tetradecapeptide, containing a disulfide bridge linking the two cysteine residues. It is released...

Anxiety Disorders

Early qEEG studies carried out in patients with obsessive-compulsive disorder (OCD) have reported either no difference or a reduced absolute power for all investigated frequency bands, with respect to healthy controls 212, 252 . However, these studies were carried out in patients on medication and in whom depressive comorbidity was not controlled for. In a study of non-depressed, drug-free OCD patients, compared with healthy controls, a reduction of delta, beta-1 and beta-2 absolute and...

Eye Movements Startle Reflex Prepulse Inhibition

Eye movements, recorded by the electro-oculogram (EOG), currently have widespread application in psychiatric research. Measured by electrodes placed horizontally or vertically surrounding the eye, they include saccadic movements from one fixation point to the next, smooth pursuit involving the tracking of a moving object together with assessment of intrusive saccades, the ability to inhibit saccades or to respond in a contrary direction (anti-saccades), blink rates and scan paths. Eye blink has...

Brief History Of Psychiatric Genetics

The idea that there is a hereditary component to mental illness is an ancient one, but psychiatric genetics, like genetics generally, only came into being as a branch of science at the beginning of the twentieth century. As far back as the 1820s, there was evidence that systematic attempts were being made to record the family histories of psychiatric patients. For example, patients' case records at the Bethlem Royal Hospital in London, England, showed that one of the routine questions that the...

HPT Axis Dysfunction in Patients with Primary Psychiatric Disorders

Excluding patients with primary endocrine disorders, a considerable amount of data has revealed an elevated rate of HPT axis dysfunction, predominantly hypothyroidism, in patients with major depression. More than 25 years ago, research groups led by Prange and Kastin demonstrated that approximately 25 of patients with major depression exhibit a blunted TSH response to TRH 8, 9 . Presumably this is due to hypersecretion of TRH from the median eminence, which leads to TRH receptor down-regulation...

Peripheral Measures Electrodermal Activity

Electrodermal activity, formerly called the galvanic skin response, has been one of the most widely utilized measures. This reflects eccrine sweat gland activity mediated by cholinergic activity and under sympathetic autonomic nervous system control. Top-down modulatory influences arise from the premotor and sensorimotor cortex, limbic structures, such as the amygdala, hippocampus, cingulate cortex, hypothalamus and the reticular formation. Electrodermal recording measures the resistance of the...

Tissue Remodelling

Another emerging theme is that of progressive brain changes and end-organ damage resulting from sustained abuse of drugs. Behavioural abnormalities associated with addiction are very long-lived. It is being increasingly appreciated that chronic drug exposure causes stable changes in the brain at the molecular and cellular levels that underlie these behavioural abnormalities 74 . A recent study with methamphetamine users illustrates this point. While illicit stimulants are often used to enhance...

Norman Sartorius

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