Книги по МРТ КТ на английском языке / Functional Neuroimaging in Child Psychiatry Ernst 1 ed 2000

Fig. 13.6. Positron emission tomography with a-[11C]-methyl-l-tryptophan showing serotonin synthesis levels in the ventral±striatal brain areas of a developmentally normal control, a patient with obsessive-compulsive disorder (OCD), and a patient before and after drug treatment with paroxetine. Higher serotonin synthesis levels correspond to the areas highlighted in yellow, while low serotonin synthesis levels correspond to areas in blue. (Created by the laboratory of Dr David Rosenberg.)

Fig. 14.1. Cortico±striato±thalamo±cortical (CSTC) circuits. White, cerebral cortex; red, caudate nucleus (labeled ªCº); green, lenticular nucleus (labeled ªLº); purple, thalamus (labeled ªThº); ASC, association cortex; SMC, sensorimotor cortex; OFC, orbitofrontal cortex; TLC, temporolimbic cortex. See Fig. 14.3a for a more detailed schematic drawing of connectivity in CSTC circuits. Here excitatory cortico±striatal projections are represented with red arrows. Projections from OFC and TLC are primarily to ventral striatum, whereas those from SMC and ASC are primarily to dorsal striatum (Leckman et al., 1997). Inhibitory striato±pallidal and pallido±thalamic projections are represented with blue arrows. Excitatory thalamo±cortical projections are not shown.

(a)

(b)

Fig. 14.3. Tic suppression. (a) Group-averaged activations in Talairach space: red indicating increased activity during tic suppression and blue decreased activity. Intersubject averaging is an imperfect visual representation of regional signiWcance testing because of the variability between subjects in the location of anatomic regions such as the basal ganglia, and variability in the spatial location of activation within subcortical and stereotactically deWned cortical regions. This is especially evident in the left basal ganglia, where the group-average map fails to indicate activation (Peterson et al., 1998). The Talairach stereotactic deWnitions of cortical regions of interest are shown in green outline. Anterior cingulate: 1, 7, 14, 21, 28, 35; posterior cingulate: 20, 27, 34, 40; frontal cortex: 2, 8, 15, 22, 29, 36; superior temporal gyrus; 3, 10, 17; middle temporal gyrus: 4, 11, 25; precentral gyrus: 9; sensorimotor cortex: 16, 23, 30, 37; inferior parietal cortex: 24, 31, 38; occipital cortex: 5, 12, 18, 26, 32; hippocampus/parahippocampus: 6; cuneus: 13, 19; and precuneus: 33, 39. (b) Basal ganglia deWnition and activation in a single subject. Region deWnitions are shown for the inferior-most slice, where basal ganglia activation was seen. In the basal ganglia deWnitions on the left, yellow indicates putamen, blue indicates globus pallidus, and red indicates caudate. In the activation map on the right, decreased activity of the putamen and globus pallidus is seen bilaterally (blue); activity during tic suppression in the caudate nucleus is increased on the right (red).

Fig. 17.1. SPECT image: coronal section of the brain showing unilateral temporal lobe hypoperfusion in

patient with early-onset anorexia nervosa.

Fig. 20.2. Regional cerebral blood Xow (rCBF) increases . 20% (p , 0.001; uncorrected) for unilateral Wnger movement in a 20-year-old patient with history of intrauterine or perinatal middle cerebral artery infarction in the right hemisphere (from Müller et al., 1998e). The activations from the H215O PET subtraction images are superimposed onto the patient's structural MRI. (a±c) A normal pattern of activations for Wnger movement of the unaVected right hand is seen in primary motor cortex and the supplementary motor area (a), as well as in the thalamus, basal ganglia, and premotor cortex of the left hemisphere (b), and in the right anterior cerebellum (c). (d±f) Activations for movement of the hemiparetic left hand. Activations in the supplementary motor area (d) are enhanced and are more bilateral compared with movement of the unaVected hand, but there is no activation in primary motor cortex. (e) Atypical activations are also seen in the hemisphere ipsilateral to the side of movement in premotor cortex and in the thalamus. (f) An unexpected activation is found in residual temporal cortex of the lesioned hemisphere. The activations for movement of the hemiparetic hand suggest that multiple regions are involved in reorganization, with the exception of the primary motor cortex.

Part 1

Techniques of functional neuroimaging

Since the mid-1980s, there has been a rapid technological development in functional neuroimaging methods that have enabled the study of the human brain in vivo. Positron emission tomography (PET), single photon emission computed tomography (SPECT), functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), and magnetoencephalography (MEG) now offer a diverse array of methods for studying metabolic and neurochemical brain development, as well as the neural systems subserving cognitive and emotional processes.

To provide a foundation for understanding these methods, particularly as applied to the study of brain development and deviance, Part 1 delineates the basic principles, advantages, and disadvantages of these modalities. Herscovitch and Ernst discuss the nuclear medicine techniques of PET and SPECT (Chapter 1) and Morris and colleagues discuss PET methods used to map receptors (Chapter 2). Eden and ZeViro then describe the recent emergence of fMRI as a technique that can be used with neurophysiologic and neurocognitive probes to deWne neural circuits and determine their integrity in childhood disorders (Chapter 3). Yurgelun-Todd and Renshaw in Chapter 4 discuss advances in MRS for the study of brain chemistry and the evolution of this technique into a brain mapping technique. Finally, in Chapter 5, Rojas and colleagues describe MEG, a technique with superior temporal resolution that directly measures neuronal electrical activity.

This diversity of functional imaging methods provides the means for mapping a variety of important brain maturational processes. These methods diVer in the nature of the recorded signal (radioactive counts, electromagnetic energy), the physiologic variables (e.g., cerebral blood Xow, glucose metabolism, receptor density, neurochemical concentration), the temporal and spatial resolution, the health risks, and the availability and cost. The neuroscientist can theoretically choose a best method or combination of methods to address scientiWc questions relating to normal and aberrant brain development. Furthermore, the integration of these techniques (multimodal imaging) will doubtlessly increase over time, oVering a more comprehensive knowledge base from which to study, diagnose, and treat psychiatric disorders.