Brain imaging: applications in psychiatry

Structural and functional imaging of brains

Analyzing the complex structures and functions of brain is the key issue to understanding the physiological and pathological processes. Although neuronal morphology and local distribution of neurons/blood vessels in the brain have been known, the subcellular structures of cells remain challenging, especially in the live brain. In addition, the complicated brain functions involve numerous functional molecules, but the concentrations, distributions and interactions of these molecules in the brain are still poorly understood. In this review, frontier techniques available for multiscale structure imaging from organelles to the whole brain are first overviewed, including magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), serial-section electron microscopy (ssEM), light microscopy (LM) and synchrotron-based X-ray microscopy (XRM). Specially, XRM for three-dimensional (3D) imaging of large-scale brain tissue with high resolution and fast imaging speed is highlighted. Additionally, the development of elegant methods for acquisition of brain functions from electrical/chemical signals in the brain is outlined. In particular, the new electrophysiology technologies for neural recordings at the single-neuron level and in the brain are also summarized. We also focus on the construction of electrochemical probes based on dual-recognition strategy and surface/interface chemistry for determination of chemical species in the brain with high selectivity and long-term stability, as well as electrochemophysiological microarray for simultaneously recording of electrochemical and electrophysiological signals in the brain. Moreover, the recent development of brain MRI probes with high contrast-to-noise ratio (CNR) and sensitivity based on hyperpolarized techniques and multi-nuclear chemistry is introduced. Furthermore, multiple optical probes and instruments, especially the optophysiological Raman probes and fiber Raman photometry, for imaging and biosensing in live brain are emphasized. Finally, a brief perspective on existing challenges and further research development is provided.

Intraperitoneal administration for sustained photoacoustic contrast agent imaging

Photoacoustic (PA) imaging at 1064 nm in the second near-infrared (NIR-II) has attracted recent attention. We recently reported a surfactant-based formulation of a NIR-II dye (BIBDAH) for NIR-II PA contrast. Here, we investigated BIBDAH as a NIR-II PA contrast agent for longitudinal preclinical PA imaging. When administered to mice by the conventional intravenous (I.V.) route, BIBDAH was rapidly cleared from circulation, as indicated by a decrease in NIR-II absorption in sampled plasma. Conversely, when mice were injected with BIBDAH by the intraperitoneal (I.P.) route, peak NIR-II absorption levels in plasma were lower initially, but there was a sustained dye presence that resulted in a more consistent concentration of dye in plasma over 2 days. Increasing the I.P. injection dose and volume resulted in increased NIR-II area under the curve (AUC) in serum. Bimodal PA and ultrasound imaging reflected these results, showing a rapid decrease in PA signal in blood with I.V. administration, but permitting sustained imaging with I.P. administration. These results show that I.P. administration can be considered as an administration route in preclinical animal studies for improved longitudinal observation with more consistent contrast signal intensity.

Effects of Processing pH on Emission Intensity of Over-1000 nm Near-Infrared Fluorescence of Dye-Loaded Polymer Micelle with Polystyrene Core

Fluorescence imaging using the over-thousand-nanometer (OTN) near-infrared (NIR) light is an emerging method for an in vivo imaging analysis of deep tissues without physical sectioning. Polymer micelle nanoparticles (PNPs) composed of organic polymers encapsulating an OTN-NIR fluorescent dye, IR-1061, in their hydrophobic core are expected to be biocompatible probes. Because IR-1061 quickly quenches due to the vibration of polar hydroxyl bonding in its surroundings, the influence of hydroxyl ions should be minimized. Herein, we investigated the effect of the hydrogen ion concentration during the preparation process using IR-1061 and an organic polymer, poly(ethylene glycol)-block-polystyrene (PEG-b-PSt), on the emission properties of the obtained OTN-PNPs. The OTN-PNP has a hydrodynamic diameter of 20 - 30 nm and emits 1110-nm fluorescence that is applicable to angiography. The loading efficiency of IR-1061 in the OTN-PNPs increased when prepared in an aqueous solution with a low hydroxyl ion concentration. In this solution (pH 3.0), highly emissive OTN-PNPs was obtained with IR-1061 at lower nominal concentrations. Decreasing the hydroxyl ion concentration during the preparation process yields highly emissive OTN-PNPs, which may improve the in vivo imaging analysis of biological phenomena in deep tissues.

Cortical metabolic patterns in schizophrenia: a mismatch with the positive-negative paradigm

The cortical metabolic patterns of 12 schizophrenics experiencing hallucinations and/or pseudo-hallucinations were investigated using positron tomography and 18F-fluoro-deoxy-glucose. Andreasen's scales were scored and the patients (all “mixed“) were classified in a “positive” or a “negative” group and compared to a group of 6 normal controls. The data were analyzed across groups for absolute metabolic rates, metabolic indices (cortical region/whole studied cortex), and specific indices exploring the sensory non-association/posterior parietal association and the prefrontal association/posterior parietal association dimensions. Whole-cortex metabolic rate in the negative group was found to be lower than both the control (P=0.02) and the positive group (P = 0.002) while the positive group did not differ significantly from the controls. We found “hypofrontality” to be without difference between the positive and the negative group (controls: 7±0.7, positive: 5.9±0.2, negative: 4.9±0.15, mean±SEM in mg/min/100 g). However, the prefrontal association/posterior parietal association ratio was increased in the negative group (P=0.02). A major finding was an increase in the posterior non-association/posterior parietal association ratio in the whole schizophrenic group as compared to the controls (P = 0.004), this being more marked in the negative (P=0.01) than in the positive group. Arguments are given to support the hypothesis that this particular increase could be related to the hallucinatory activity of the patients.

Volumetric MRI Analysis of a Case of Severe Ventriculomegaly

We present a case of a 60-year-old male referred to a tertiary psychiatric facility for diagnostic assessment due to low mood and behavioral changes. Neurological examination of the patient was unremarkable. Magnetic resonance imaging (MRI) indicated overt ventriculomegaly with gross dilatation of lateral and third ventricles. Manual segmentation of gray matter, white matter and cerebrospinal fluid demonstrated that the patient had a ventricular volume almost 46 times greater than that of healthy volunteers in the same age range. Despite his striking degree of ventriculomegaly and cortical thinning, he presented primarily with psychiatric and cognitive complaints. These represented a major neurocognitive disorder. His behavior improved with a structured environment and routine instituted by the treating team. This is a dramatic example of the brain's response to extreme structural remodeling. Elements of pluripotentiality may counteract degeneracy to preserve functions in cases of serious structural stress in the brain. Changes in the neural circuitry of emotional processing, and/or disruption in signaling pathways important for synaptogenesis may influence depression pathophysiology. How this circuitry is modified in cases of extreme structural stress such as long-standing overt ventriculomegaly, is unclear. This case demonstrates the ability of the brain to generate a normal phenotype despite structural changes that seem incompatible with advanced cognitive function, illustrating the substantial potential for adaptability and plasticity in the brain.

Examining neural correlates of psychopathology using a lesion-based approach

Studies of individuals with focal brain damage have long been used to expand understanding of the neural basis of psychopathology. However, most previous studies were conducted using small sample sizes and relatively coarse methods for measuring psychopathology or mapping brain-behavior relationships. Here, we examined the factor structure and neural correlates of psychopathology in 232 individuals with focal brain damage, using their responses to the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF). Factor analysis and voxel-based lesion symptom mapping were used to examine the structure and neural correlates of psychopathology in this sample. Consistent with existing MMPI-2-RF literature, separate internalizing, externalizing, and psychotic symptom dimensions were found. In addition, a somatic dimension likely reflecting neurological symptoms was identified. Damage to the medial temporal lobe, including the hippocampus, was associated with scales related to both internalizing problems and psychoticism. Damage to the medial temporal lobe and orbitofrontal cortex was associated with both a general distrust of others and beliefs that one is being personally targeted by others. These findings provide evidence for the critical role of dysfunction in specific frontal and temporal regions in the development of psychopathology.

The Sensed Presence as Right Hemispheric Intrusions into the Left Hemispheric Awareness of Self: An Illustrative Case Study

The hypothesis of vectorial hemisphericity predicts that left hemispheric intrusions of the right hemispheric equivalent of the sense of self should be associated with the experience of a “presence” of someone else. The neurophenomenological profile of a woman whose medical history satisfied these theoretical criteria (verified electrical anomalies that could encourage phasic discharges within the right temporal lobe and atrophy within the left temporoparietal region) is presented. In addition to interactions between electrical seizures and thinking, she reported a long history of sensed presences, ego-alien intrusions, and “sudden knowing of the subsequent sequences of seizures” before they occurred clinically. The existence of these neurocognitive processes demands a reevaluation of the psychiatric default explanations of “hysteria” and questions the belief that “awareness during seizures” or “premonition of subsequent somatosensory experience” contraindicates an epileptic process.

The prevalence of abnormal findings in screening CT brains performed on patients admitted with psychiatric symptoms

Background: No clear guidelines exist regarding the role of computerised tomography (CT) as a screening neuroimaging tool in psychiatric practice. The aim of this study was to evaluate the usefulness of historical and clinical parameters on the CT request form, identify the spectrum of CT findings and correlate these to develop guidelines for the use of screening CT brains in patients who present with psychiatric symptoms.Methods: Requests and reports for the brain CT’s of 507 consecutive patients over a 2-year period, between 2013 and 2014, referred from a psychiatric institute for screening CT brain scans, were reviewed. Analysis was performed for the history of trauma and seizures, Glasgow Coma Scale (GCS) score, focal neurological signs, papilloedema, electroencephalograph, relevant blood results and abnormal CT findings. All reports were approved by a consultant radiologist.Results: No abnormality was noted in 69% of CT scans. Cerebral atrophy, infarcts, cysts and calcific foci were present in 30% of patients. One patient presenting with focal neurology had a CT demonstrating an extradural haematoma which required neurosurgical intervention. No focal brain lesions, potentially responsible for the psychosis, were identified in any other patient.Conclusion: Routine CT screening of patients who present with psychotic symptoms, in the absence of focal neurological deficit, does not add value to patient outcome, but rather contributes to the escalating health care expenses and unnecessary radiation dose. CT screening of psychiatric patients should be reserved for patients with reliable predictors of intracranial abnormalities such as lateralising signs, seizures, persistent or worsening headaches; decrease in GCS, papilloedema and in patients where the onset of symptoms occurred at an age above 50.

CNS Assessment Using Functional Neuro-PET Imaging

Disorders of the brain manifest in a variety of manners ranging from feeling or thought abnormalities to total paralysis. Until recently, most imaging methods of the brain have been limited to anatomic considerations, with little information about actual function of the brain except that deduced from clinical examination and physical and cognitive assessment testing. With the advent of positron emission tomography (PET) and enhanced computer and scintigraphic image detection systems, there is keen interest in applying this imaging technique to better understand brain physiology and pathophysiology. Potential applications of PET in CNS assessment is expanding avenues for improved diagnosis and staging of disease, as well as monitoring therapeutic interventions. A general review of the radiopharmaceuticals used for neuro-PET imaging, as well as their application in situations such as cerebrovascular disease, brain activation studies, various movement disorders and dementias, depression, epilepsy, obsessive-compulsive disorder, schizophrenia, and neuropharmacology (including cerebral receptor studies) will be presented.

Molecular imaging as a guide for the treatment of central nervous system disorders

Molecular imaging techniques have a number of advantages for research into the pathophysiology and treatment of central nervous system (CNS) disorders. Firstly, they provide a noninvasive means of characterizing physiological processes in the living brain, enabling molecular alterations to be linked to clinical changes. Secondly, the pathophysiological target in a given CNS disorder can be measured in animal models and in experimental human models in the same way, which enables translational research. Moreover, as molecular imaging facilitates the detection of functional change which precedes gross pathology, it is particularly useful for the early diagnosis and treatment of CNS disorders.

This review considers the application of molecular imaging to CNS disorders focusing on its potential to inform the development and evaluation of treatments. We focus on schizophrenia, Parkinson's disease, depression, and dementia as major CNS disorders. We also review the potential of molecular imaging to guide new drug development for CNS disorders.

The neuroimmunology of schizophrenia

Schizophrenia (SCZ) is a polygenic, multi-factorial disorder and a definitive understanding of its pathophysiology has been lacking since it was first described more than a century ago. The predominant pharmacological approach used to treat SCZ is the use of dopamine receptor antagonists. The fact that many patients remain symptomatic, despite complying with medication regimens, emphasises the need for a more encompassing explanation for both the causes and treatment of SCZ. Recent neuroanatomical, neurobiological, environmental and genetic studies have revived the idea that inflammatory pathways are involved in the pathogenesis of SCZ. These new insights have emerged from multiple lines of evidence, including the levels of inflammatory proteins in the central nervous system of patients with SCZ and animal models. This review focuses on aberrant inflammatory mechanisms present both before and during the onset of the psychotic symptoms that characterise SCZ and discusses recent research into adjunctive immune system modulating therapies for its more effective treatment.

Is psychiatry scientific? A letter to a 21st century psychiatry resident

During the development of the DSM-5, even the lay press questioned psychiatr's scientific validity. This review provides 21st century psychiatry residents with ways of answering these attacks by defining the concepts and history of psychiatry (a branch of medicine), medicine and science. Psychiatric language has two levels: first, describing symptoms and signs (19th century descriptive psychopathology developed in France and Germany), and second, describing disorders (psychiatric nosology was developed in the early 20th century by Kraepelin and resuscitated by the US neo-Kraepelinian revolution leading to the DSM-III). Science is a complex trial-and-error historical process that can be threatened by those who believe too much in it and disregard its limitations. The most important psychiatric advances, electroconvulsive therapy and major psychopharmacological agents, were discovered by "chance", not by scientific planning. Jaspers's General Psychopathology is a complex 100-year-old book that describes: 1) psychiatric disorders as heterogeneous and 2) psychiatry as a hybrid scientific discipline requiring a combination of understanding (a social science method) and explanation (a natural science method). In the 21st century Berrios reminds us of psychiatry's unfortunate methodological issues due to hybrid symptoms and disorders, some of which are better understood as problems in communication between interacting human beings; in those situations neuroscience methods such as brain imaging make no sense. A new language is needed in psychiatry. East Asian psychiatry residents, who are not particularly attached to the antiquated language currently used, may be particularly equipped for the task of recreating psychiatric language using 21st century knowledge.

Misunderstanding psychopathology as medical semiology: an epistemological enquiry

In our everyday clinical experience we encounter significant problems directly related to the instability of psychopathological concepts. In order to trace the origin of this inconsistency, the nature of these concepts will be explored in their historical development. They will be compared to those pertaining to medical semiology, paying special attention to the specific nature of the 'object' each of them refers to. While concepts belonging to medical semiology refer to natural objects and retain their meaning independently of the patient's context, psychopathological concepts refer to fragments of experience, which lose their significance if detached from their contextual horizon. The instability of psychopathological concepts is a consequence of the misunderstanding of psychopathology as medical semiology. As an alternative to this view, it will be argued that psychopathology represents an active and never-ending process aimed at the creation of intelligibility.

Research applications of magnetic resonance spectroscopy to investigate psychiatric disorders

Advances in magnetic resonance spectroscopy (MRS) methodology and related analytic strategies allow sophisticated testing of neurobiological models of disease pathology in psychiatric disorders. An overview of principles underlying MRS, methodological considerations, and investigative approaches is presented. A review of recent research is presented that highlights innovative approaches applying MRS, in particular, hydrogen MRS, to systematically investigate specific psychiatric disorders, including autism spectrum disorders, schizophrenia, panic disorder, major depression, and bipolar disorder.

Is computed tomography still useful as a neuroimaging tool in psychiatry?

BACKGROUND

Computed tomography (CT) has played a pivotal role in psychiatry from its inception; however with the advent of other high-resolution noninvasive neuroimaging techniques such as MRI, the field has gone through a dramatic transformation.

OBJECTIVE

This article will explore the current role of CT in psychiatry.

METHODS

An extensive search of the published literature (1970 - 2008) was conducted, employing a number of databases and terms relevant to CT and imaging.

RESULTS/CONCLUSION

At present CT is primarily used as a screening tool to exclude intracranial pathology. This is partly because it is widely available and less expensive than other imaging modalities. CT is unable to provide region-specific information like MRI and this has restricted its use in disorders in which functional disturbances are suspected, however it remains the preferred mode of investigation where gross structural abnormalities are suspected.

A space for measuring mind and brain: interdisciplinarity and digital tools in the development of brain mapping and functional imaging, 1980-1990

Brain mapping is said to have opened up the possibility of a new collaboration between the sciences of mind and the sciences of the brain, potentially leading to a new kind of scientist, sometimes called "cognitive neuroscientist." This article traces the recent history of brain mapping and analyzes the processes that have led to a new "close working relationship" between the sciences of mind and brain. A key part of the working relationship is shown to be constituted through the development of the Talairach system, a digital space in which to measure structure and function. The development of meaningful brain mapping data involves the creation of measurement spaces that allow interdisciplinary collaboration and is not the result solely of theoretical developments or of the application of a technology.

Real-time functional magnetic resonance imaging

Magnetic resonance imaging (MRI) has been shown to be useful in the detection of brain activity via the relatively indirect coupling of neural activity to cerebral blood flow and subsequently to magnetic resonance signal intensity. Recent technical advances have made possible the continuous collection of successive images at a rate rapid compared with such signal changes and in the statistical processing of these image time series to produce tomographic maps of brain activity in real time, with updates of 10 frames/s or better. We describe here our preferred method of real-time functional MRI and some of the early results we have obtained with its use.

Mind over matter? II: implications for psychiatry

OBJECTIVE

To explore concepts of causality within the mind and aetiology of psychiatric disorders in the light of the proposed formulation of the mind-brain problem.

METHOD

Taking the two propositions of this formulation as 'first principles' a logical analysis is attempted.

RESULTS AND CONCLUSIONS

Neural activity cannot in principle be regarded as causing mental activity, or vice versa. Causal processes are most coherently conceptualised in terms of the 'mind-brain' system. Determination of causal and aetiological effects will always necessitate consideration of contextual evidence. Because of the 'explanatory gap' between explanation in neurophysiological terms and 'mentalistic' terms, whenever formulation in mentalistic terms is possible this will carry greater explanatory power; that is, it will carry meaning in the way a neural formulation cannot.

Similarity and variation in gene expression among human cerebral cortical subregions revealed by DNA macroarrays: technical consideration of RNA expression profiling from postmortem samples

The functional regionality of the human cerebral cortex suggests that a set of genes might be activated in each subregion of the neocortex to support its specific functions. To test this hypothesis, we employed the DNA array technique to compare the mRNA expression profiles of three neocortical subregions of the human brain: prefrontal cortex (Area 46), motor cortex (Area 4) and visual cortex (Area 17). The macroarray analysis on high quality mRNA from postmortem brains revealed that the expression profiles of the different cortical areas are almost similar: only six out of 1088 known genes exhibited significant differences (>2-fold) in their expression. RT-PCR studies with an increased number of samples confirmed that expression of only two genes, annexin II and early growth response protein 1, varied by 2-fold among the regions, whereas expression of the others showed large inter-individual difference. These results suggest that the whole neocortex of humans is more homogeneous than we expected at the level of gross gene expression profiles. In parallel, sensitivity and accuracy of radioisotope-based DNA macroarrays and fluorescence-based DNA microarrays were tested.

The development of a potential single photon emission computed tomography (SPECT) imaging agent for the corticotropin-releasing hormone receptor type

A high-affinity radioligand for CRHR1 has been prepared that can serve as a template for the development of SPECT imaging agents. The 5-chloro-N-cyclopropylmethyl-N-(2,6-dichloro-4-iodophenyl)-2-methyl-N-propylpyrimidine-4,6-diamine (6b, Ki = 14 nM), and the corresponding 4-bromophenyl analogue (6a, Ki = 21 nM), were synthesized in four steps from compound 3.

Is the attentional dysfunction in schizotypy related to anxiety?

Two factors, 'anxiety-loaded' (AL) and 'perceptual-disorganization' (PD), emerged in a factor analysis of the Schizotypal Personality Questionnaire (SPQ). Sixty of the 219 participants performed a latent inhibition (LI) task. During the pre-exposure phase, one group was exposed to repeated non-reinforced presentations of an irrelevant stimulus and the other was not pre-exposed. In the subsequent test phase, learning was slower in the pre-exposed group than in the non-pre-exposed group. The LI effect was assessed, separately, as a function of SPQ, trait-anxiety sub-scale (TASS) of the State and Trait Anxiety Inventory (STAI), and AL and PD factors scores. LI was disrupted in participants with either high scores on SPQ, STAI, or the AL factor. A regression analysis indicated that both TASS and SPQ independently accounted for LI disruption in high schizotypals, but that the contribution of TASS was stronger. It was suggested that the anxiety component of schizotypy, more than the perceptual-disorganization (schizophrenia-like) component, accounts for the attentional dysfunction in high schizotypals, and for their greater than normal distraction by irrelevant stimuli.

Schizophrenia: the fundamental questions

Identifying the correct phentotype of schizophrenia is perhaps the most important goal of modern research in schizophrenia. This identification is the necessary antecedent of indentifying the pathophysiology and etiology. A working model is proposed, which suggests that the phenotype should be defined on the basis of abnormalities in neural circuits and a fundamental cognitive process. This type of unitary model may be more heuristic than early ones that were based on heterogeneous signs and symptoms.

Dopamine-antagonistic, anticholinergic, and GABAergic effects on declarative and procedural memory functions

Declarative and procedural memory functions are related to dissociable neuroanatomic substrates. In the present study differential effects of pharmacologically induced changes in dopaminergic, GABAergic, and cholinergic activity in the brain on declarative (object and face recognition, immediate and delayed word recall) and procedural memory processes (compensatory tracking) were investigated. In a double-blind design, either 3 mg of haloperidol, 11 mg of midazolam, 1 mg of scopolamine, or placebo were administered to 80 healthy volunteers randomly assigned to one of the four drug conditions. Although all three drugs produced a detrimental effect on immediate and delayed word recall, recall performance was substantially more impaired by the benzodiazepine midazolam than by either haloperidol or scopolamine. While recognition of faces was affected by neither of the drugs, performance on object recognition was significantly decreased by midazolam as compared to placebo. Procedural learning was markedly impaired by all drugs but, again, the observed effect was most pronounced with midazolam. Additional analyses of measures of subjective activation, cortical arousal, and psychomotor performance argued against the assumption that the observed memory-impairing effects were secondary to drug-induced sedation. The overall pattern of results revealed that memory processes are much more susceptible to changes in GABAergic than in dopaminergic or cholinergic neurotransmitter activity. Furthermore, the present findings point to the conclusion that the modulating effects of dopaminergic, GABAergic, and cholinergic neurotransmitter systems on declarative and procedural memory functions are less specific than suggested by neuropsychological studies in patients.

GABA-ergic neurons and the neurobiology of schizophrenia and other psychoses

There are a number of disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM IV) that are characterised by having psychotic symptoms as the defining feature [17]. The narrowest definition of psychosis is restricted to delusions or prominent hallucinations, with the hallucinations occurring in the absence of insight into their pathological nature. Schizophrenia is the most prevalent form of psychosis, but this may also occur due to other medical conditions (e.g., Prader-Willi syndrome, epilepsy), in the early post-partum period, at menopause, and as a result of drug use. This article attempts to draw together an underlying causation across the various forms of psychotic disorder and, by integrating this with what is known about the genetics, neuroanatomy and neuropharmacology of the positive symptoms in schizophrenia, produce a broader understanding. At the cellular level, gamma-aminobutyric acid (GABA)-ergic interneurons are a common feature in psychotic states, and are a principal focus for serotonin and dopamine innervations, as well as playing an important role in cortical development. At the systems level, prefrontal and medial temporal cortices are implicated with activity levels out of synchrony in schizophrenics. How these vast areas of disparately functioning cortical networks are "bound" together to provide coherent conscious experiences is again a function of GABA-ergic interneurons. These interneurons have highly divergent inhibitory projections to large numbers of pyramidal neurons and are themselves synchronised by the ascending dopamine and serotonin innervations.

The reduced neuropil hypothesis: a circuit based model of schizophrenia

In recent years, quantitative studies of the neuropathology of schizophrenia have reignited interest in the cerebral cortex and focused attention on the cellular and subcellular constituents that may be altered in this disease. Findings have ranged from compromised circuitry in prefrontal areas to outright neuronal loss in temporal and cingulate cortices. Herein, we propose that a reduction in interneuronal neuropil in the prefrontal cortex is a prominent feature of cortical pathology in schizophrenia and review the growing evidence for this view from reports of altered neuronal density and immunohistochemical markers in various cortical regions. The emerging picture of neuropathology in schizophrenia is one of subtle changes in cellular architecture and brain circuity that nonetheless have a devastating impact on cortical function.

Neuroimaging in psychiatry

The promise of neuroimaging as an aid to diagnosis is discussed, and findings from the most accessible imaging techniques are reviewed. In addition, some of the earliest findings from functional MR imaging and other technologies are presented with several illustrations. Strategies for interpretation, critique of imaging techniques, and review of major findings for brain injury, mood, anxiety, schizophrenia, and attention deficit disorders are offered. Examples of normal and pathologic images illustrate actual cases and examples of the newer imaging technologies.

Intra- and interhemispheric electroencephalogram coherence in siblings discordant for schizophrenia and healthy volunteers

Former studies had pointed to an increased electroencephalogram (EEG) coherence in schizophrenics, but it remained unsolved whether this deviation represents the premorbid state or is only a consequence of the current or previous schizophrenic episodes. To clarify this question, we tested the hypothesis that subjects at elevated risk also reveal higher coherences compared to healthy controls. For that, intra- and interhemispheric EEG coherences were investigated in untreated schizophrenics, their healthy siblings, and healthy controls. Differences were only found regarding the intrahemispheric coherences. Both in schizophrenics and, even though to a lesser degree, in their siblings significantly higher coherence estimates were found compared to the control group. The results are in accordance with the assumption that schizophrenia is predominantly a neurodevelopmental disease. Increased coherence might be assumed to be a vulnerability marker for schizophrenia reflecting maldevelopment of the brain before onset of the disorder.

The role of the thalamus in schizophrenia

BACKGROUND

Explaining the diversity of symptoms that occur in schizophrenia is a major conceptual challenge. Perhaps the most powerful strategy is to identify a fundamental cognitive process and/or a fundamental neural circuit.

METHODS

Convergent data from our research group in Iowa and from investigators in other centres are summarized.

RESULTS

The thalamus plays a key role in information processing. A defect in circuitry connecting the thalamus, frontal cortex, and cerebellum could explain a wide range of symptoms. Neuropathology and imaging studies suggest that patients with schizophrenia may have abnormalities in this circuitry.

CONCLUSION

The fundamental deficit in schizophrenia may be conceptualized as a "cognitive dysmetria" characterized by impairments in coordinating the perception, encoding, retrieval, and prioritization of experience and information.

Dopamine in schizophrenia

The DA hypothesis of schizophrenia is one of the oldest biological hypotheses of schizophrenia with many revised versions. However, it is unlikely that any single neurotransmitter hypothesis is able to explain the biological basis of such a highly heterogenous disorder as schizophrenia in a satisfactory way. Rather, it is evident that the biological vulnerability factors and the 'acute neurophysiology' of schizophrenic symptoms involve a complex set of imbalances of aberrant connections in neuronal circuits in the brain. Dopamine is likely to be one of the transmitter substances involved, as evidenced by recent neuroimaging studies in neuroleptic-naive schizophrenia. Regardless of whether the DA hypothesis of schizophrenia is true or not, the DA hypothesis of neuroleptic drug action still has a relatively solid basis. The DA D2 receptor blockade remains the best characterized clinically useful mechanism of drug action to alleviate psychotic symptoms. The ongoing and future work on the precise role of DA in schizophrenia should focus on first-episode/admission neuroleptic-naive schizophrenic patients. Such studies represent the best opportunity of finding out specific changes in the dopaminergic pathways and relating them in a meaningful way to various dimensions of psychopathology seen in schizophrenic patients.

How we think about cognition, emotion, and biology in psychopathology

The variety of potential relationships assumed between psychological and biological concepts fosters considerable misunderstanding of what our data can tell us. A naively reductionistic view of psychological concepts is prevalent, particularly in the psychopathology literature. A series of examples of the application of psychophysiological methods in studies of cognition, emotion, and psychopathology provides a background for a discussion of these problems. Unwarranted distinctions between cognition and emotion, between classes of measures, and between psychological and biological approaches to understanding normal functioning and psychopathology undermine the ability of cognitive neuroscience to achieve its considerable potential. A nondualistic, nonreductionistic, non-interactive relationship is recommended, with psychological and biological concepts both having central, necessary, and distinct roles.

Neonatal insult to the hippocampal region and schizophrenia: a review and a putative animal model

OBJECTIVE

To review the mounting evidence implicating early hippocampal dysfunction in the pathogenesis and the pathophysiology of schizophrenia. An account is made of recent neurodevelopmental hypotheses indicating how an early dysfunction of the hippocampal region disrupts maturational events in brain systems connected to that structure, thus inducing dysfunctional connectional development. Finally, an animal model is presented.

METHOD

Socioemotional behaviour of monkeys (Macaca mulatta) with selective neonatal hippocampal lesions was assessed by analyzing their interactions with their age-matched controls at 2 months, 6 months, and 5 to 8 years of age and by comparing the social interactions at each age with those of normal controls paired together.

RESULTS

At 2 months of age, monkeys with neonatal hippocampal lesions presented minor disturbances in initiation of social interactions. These subtle changes of behaviour were less evident at 6 months, although by that age, the operated monkeys displayed more withdrawals in response to an increase in aggressive responses from their unoperated peers. In adulthood, the amount of time spent by the hippocampectomized monkeys in social contacts with their normal peers decreased markedly. In addition, operated monkeys exhibited more locomotor stereotypies than normal controls.

CONCLUSION

These experimental findings indicate that the time-course and nature of the behavioural disturbances resulting from early trauma to the hippocampal region have some similarities with the clinical symptoms of schizophrenic patients and the typical time-course of the disease.

Tyrosine transport as an indicator of cell membrane dysfunction in schizophrenia

In a series of studies tyrosine transport was investigated in patients with schizophrenia. Plasma amino acids competing with tyrosine for transport with the L-system were found to be elevated, and correlated negatively with homovanillic acid levels in the cerebrospinal fluid of the patients. The results were interpreted as a decrease in the transport of tyrosine to the brain leading to a reduced dopamine turnover. In in vitro studies with fibroblasts the transport capacity of tyrosine was found to be decreased (a lower Vmax value) in the patients. No changes in transport mechanism for the other neutral amino acids were found. The finding of a lower transport capacity in patients was replicated in a new sample in whom tyrosine transport also was determined in vivo with positron emission tomography. The in vivo studies demonstrated a decrease in the influx of tyrosine across the blood-brain barrier. Altogether the results were interpreted in support of the view of schizophrenia as a systemic disorder with a primary disturbance in cell membrane function.

Observation of metabolic changes in chronic schizophrenia after neuroleptic treatment by in vivo hydrogen magnetic resonance spectroscopy

RATIONALE AND OBJECTIVES

The authors investigate: (1) whether there is a lateral effect of hydrogen (1H) magnetic resonance (MR) spectroscopy observable metabolite ratios between the right and the left prefrontal lobe in chronic schizophrenia; (2) whether there is a change of proton metabolite ratios in chronic schizophrenia after neuroleptic treatment; (3) whether there is a relation between changes in 1H MR spectra and the clinical assessment of Brief Psychiatric Rating Scale (BPRS); and (4) to investigate a hypofrontality hypothesis in schizophrenia in terms of neurochemical aspects.

METHODS

Localized in vivo 1H MR spectroscopy was used to measure the metabolite levels in the prefrontal lobes of control persons (n = 20) and of chronic patients before and after neuroleptic treatment (n = 34). The MR spectra of 8 cm3 voxels were compared with clinical assessment of BPRS in each subject.

RESULTS

No significant metabolic lateral effect was established in both schizophrenia and control groups (P > 0.05). After neuroleptic treatment, chronic schizophrenic patients generally demonstrated a decrease of the complex of gamma-aminobutyric acid (GABA) and glutamate (Glu) containing (GABA + Glu)/creatine (Cr) ratio.

CONCLUSIONS

The current follow-up 1H MR spectroscopy study shows a significant correlation between alterations of (GABA + Glu)/Cr ratio and BPRS, and supports a hypofrontality hypothesis in chronic schizophrenia. The reduction of (GABA + Glu)/Cr ratio after neuroleptic treatment may implicate the recovery of normal neuronal function in neurotransmitters. In vivo 1H MR spectroscopy may be a useful modality in follow-up evaluation of neuroleptic treatment in chronic schizophrenia.

Neuropsychological principia brevita: an application to traumatic (acquired) brain injury

The concepts and discoveries of modern neuroscience now challenge many of the presumptions that influence diagnostic decisions within neurology, psychiatry, and clinical neuropsychology. Many of these presumptions are derived from archaic bivariate models such as the mind-body argument, organic-functional dichotomy, and single lesion-single behaviour causality. Thirteen basic principles which may be useful for inferring more reliable and accurate relationships between microstructural function an clinical manifestations are developed.

Abnormalities in midline attentional circuitry in schizophrenia: evidence from magnetic resonance and positron emission tomography

The syndrome of schizophrenia presents with a complex array of symptoms that are difficult to explain at the neural level. Data collected using magnetic resonance (MR) and positron emission tomography (PET) suggest that this complex array could occur as a consequence of misconnections and mismatches in midline circuitry that is reticular-thalamic-cingulate-cortical. MR studies have shown a variety of abnormalities, including callosal agenesis, cavum septi pellucidi, decreased thalamic size, decreased frontal size, and changes in signal intensity in white matter tracts between the thalamus and the frontal cortex. PET studies using a dichotic listening paradigm suggest that patients suffering from schizophrenia have brain blood flow abnormalities consistent with a difficulty in focusing or shifting attention, which may reflect the functional substrate of the anatomic abnormalities.

Differential ratings of pleasantness following right and left hemispheric application of low energy magnetic fields that stimulate long-term potentiation

A total of 40 normal men and women were exposed under double blind conditions for 20 min to either sham-conditions or to 1 microT (10 mG) electromagnetic fields (known to produce long-term potentiation within hippocampal slices) that were applied primarily over the right temporal lobe, over the left temporal lobe or over both temporal lobes homogeneously. The men and women who received the stimulation over the right hemisphere rated their experiences as significantly more pleasant than those who received the same stimulation over the left hemisphere [eta = 0.51]. Covariance for the variation in ambient geomagnetic activity, which was negatively correlated with pleasantness, increased the significance of the experimental treatment. The potential clinical utility of applying computer-generated local and penetrative but weak intensity complex magnetic fields over portions of the human brain is discussed.

Positive and negative symptoms of schizophrenia: past, present, and future

The "group of schizophrenias," normally referred to with a single nominative, is phenomenologically heterogeneous. Its symptoms represent multiple psychological domains, including perception, inferential thinking, language, attention, social interaction, emotion expression, and volition. Studies of psychopathology have simplified this complex array in several ways; one has been a subdivision into positive and negative symptoms. Reports by our group and others suggest that the symptoms of schizophrenia fall into three natural dimensions: positive symptoms subdivided into psychotic and disorganized dimensions, while a third negative dimension also emerges. Since these dimensions have impressive consistency across studies, future work must examine their relationship to clinically relevant concepts such as prognosis or etiology and examine four different aspects: longitudinal course, neural mechanisms, relationship to treatment, and interrelationships in other pathological conditions.

The sensed presence as right hemispheric intrusions into the left hemispheric awareness of self: an illustrative case study

The hypothesis of vectorial hemisphericity predicts that left hemispheric intrusions of the right hemispheric equivalent of the sense of self should be associated with the experience of a "presence" of someone else. The neurophenomenological profile of a woman whose medical history satisfied these theoretical criteria (verified electrical anomalies that could encourage phasic discharges within the right temporal lobe and atrophy within the left temporoparietal region) is presented. In addition to interactions between electrical seizures and thinking, she reported a long history of sensed presences, ego-alien intrusions, and "sudden knowing of the subsequent sequences of seizures" before they occurred clinically. The existence of these neurocognitive processes demands a reevaluation of the psychiatric default explanations of "hysteria" and questions the belief that "awareness during seizures" or "premonition of subsequent somatosensory experience" contraindicates an epileptic process.

Computerized EEG and brain imaging studies in untreated schizophrenic patients: a report of seven cases

We undertook routine EEG, Z-map, CT and PET scans in seven acute untreated schizophrenics. Routine EEGs showed slower activity in only one case. However, the Z-map showed slower activity in all the cases. CT demonstrated brain atrophy in three of the cases, and PET revealed hypofrontality in two, right hypoparietality in four, and both conditions in one case. There was no relation between CT and PET or the Z-map. However, a significant increase in alpha 1 activity was demonstrated on the Z-map in cases who were found to be the parietal type on PET; this was not conspicuous in the frontal type on PET. Moreover, in three of the patients, the Z-map findings were similar to the lesion indicated on PET.

Dopamine D4 receptors elevated in schizophrenia

Although the biological basis of schizophrenia is not known, possible causes include genetic defects, viruses, amines, brain structure and metabolism, neuroreceptors, and G proteins. The hypothesis of dopamine overactivity in schizophrenia is based on the fact that neuroleptics block dopamine D2 receptors in direct relation to their clinical antipsychotic potencies. Moreover, dopamine D2 or D2-like receptors are elevated in postmortem schizophrenia brain tissue. This elevation, however, is only found in vivo using [11C]methylspiperone but not [11C]raclopride. The dopamine D4 receptor gene has not yet been excluded in schizophrenia because the 21 gene variants of D4 have not yet been tested. Because the link between D1 and D2 receptors is reduced in schizophrenia tissue, we tested whether one component of this link was sensitive to guanine nucleotide. We report here that the binding of [3H]raclopride to D2 receptors in schizophrenia was not sensitive to guanine nucleotide. This finding permitted analysis of data on the binding of [3H]emonapride to the D2, D3 and D4 receptors. We conclude that the combined density of D2 and D3 receptors (labelled by [3H]raclopride) is increased by only 10% in schizophrenia brain, as found by Farde et al., but that it is the density of dopamine D4 receptors which is sixfold elevated in schizophrenia. These findings resolve the apparent discrepancy, mentioned above, wherein the density of [11C]methylspiperone-labelled sites (D2, D3 and D4), but not that of [11C]raclopride-labelled sites (D2 and D3), was found elevated in the schizophrenia striatum.

Shifts in the Plutchik emotion profile indices following three weekly treatments with pulsed vs continuous cerebral magnetic fields

Compared to baseline measures, the emotional profile indices of normal volunteers who received 3 weekly exposures to 20 min. of bilateral burst-firing magnetic fields along the temporal plane displayed increased aggression and decreased trust relative to those exposed to pulsed (1 sec. every 4 sec.) fields or to control conditions. The effect size was equivalent to an eta of 0.70. There were no shifts in Holtzman Inkblot Projection Scores. These results suggest that brief cerebral exposures to weak magnetic fields that simulate the burst-firing of amygdaloid cells may affect specific limbic emotions.

Left superior temporal blood flow increases in schizophrenic and schizophreniform patients with auditory hallucination: a longitudinal case study using 123I-IMP SPECT

Serial assessments of regional cerebral blood flow were performed using 123I-IMP SPECT in two schizophrenic and three schizophreniform patients with persistent auditory hallucination. The initial SPECT study in the period with prominent auditory hallucination revealed an increased accumulation of 123I-IMP in the left superior temporal area which corresponded to the auditory association cortex. In the follow-up SPECT study performed after clinical improvement, the distribution of 123I-IMP had normalized. One of the case with schizophrenia showed a similar increased uptake of 123I-IMP in the left superior temporal area in the third SPECT scan performed when a psychotic relapse with auditory hallucination occurred. MRI scans in two of the five patients demonstrated reduced volume of the temporal lobes. These findings suggest that the auditory hallucinations in schizophrenia may be involved in functional hyperactivity in the left superior temporal cortex which might be based partly on structural abnormalities in the temporal lobes.