Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Anatomical, physiological and functional neuroimaging studies suggest that the cerebellum participates in the organization of higher order function, but there are very few descriptions of clinically relevant cases that address this possibility. We performed neurological examinations, bedside mental state tests, neuropsychological studies and anatomical neuroimaging on 20 patients with diseases confined to the cerebellum, and evaluated the nature and severity of the changes in neurological and mental function. Behavioural changes were clinically prominent in patients with lesions involving the posterior lobe of the cerebellum and the vermis, and in some cases they were the most noticeable aspects of the presentation. These changes were characterized by: impairment of executive functions such as planning, set-shifting, verbal fluency, abstract reasoning and working memory; difficulties with spatial cognition including visual-spatial organization and memory; personality change with blunting of affect or disinhibited and inappropriate behaviour; and language deficits including agrammatism and dysprosodia. Lesions of the anterior lobe of the cerebellum produced only minor changes in executive and visual-spatial functions. We have called this newly defined clinical entity the 'cerebellar cognitive affective syndrome'. The constellation of deficits is suggestive of disruption of the cerebellar modulation of neural circuits that link prefrontal, posterior parietal, superior temporal and limbic cortices with the cerebellum.

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The cerebellar cognitive affective syndrome.

Pathological disturbances of mood may follow a 'bipolar' course, in which normal moods alternate with both depression and mania, or a 'unipolar' course, in which only depression occurs. Both bipolar and unipolar disorders can be heritable illnesses associated with neurochemical, neuroendocrine and autonomic abnormalities. The neurobiological basis for these abnormalities has not been established. Using positron emission tomographic (PET) images of cerebral blood flow and rate of glucose metabolism to measure brain activity, we have now localized an area of abnormally decreased activity in the prefrontal cortex ventral to the genu of the corpus callosum in both familial bipolar depressives and familial unipolar depressives. This decrement in activity was at least partly explained by a corresponding reduction in cortical volume, as magnetic resonance imaging (MRI) demonstrated reductions in the mean grey matter volume in the same area of 39 and 48% in the bipolar and unipolar samples, respectively. This region has previously been implicated in the mediation of emotional and autonomic responses to socially significant or provocative stimuli, and in the modulation of the neurotransmitter systems targeted by antidepressant drugs.

Subgenual prefrontal cortex abnormalities in mood disorders

Basal ganglia and cerebellar loops: motor and cognitive circuits.

Controversy surrounds the function of the anterior cingulate cortex. Recent discussions about its role in behavioural control have centred on three main issues: its involvement in motor control, its proposed role in cognition and its relationship with the arousal/drive state of the organism. I argue that the overlap of these three domains is key to distinguishing the anterior cingulate cortex from other frontal regions, placing it in a unique position to translate intentions to actions.

Primate anterior cingulate cortex: where motor control, drive and cognition interface.

Regional cerebral blood flow was measured with H2 15O positron emission tomography in four patients with obsessive-compulsive disorder. Patients were scanned on 12 occasions in the same session, with each scan paired with brief exposure to one of a hierarchy of contaminants that elicited increasingly intense urges to ritualise. The relationship between symptom intensity and regional cerebral blood flow (rCBF; an index of neural activity) was subsequently examined in the group and in individual patients. The group showed significant positive correlations between symptom intensity and blood flow in the right inferior frontal gyrus, caudate nucleus, putamen, globus pallidus and thalamus, and the left hippocampus and posterior cingulate gyrus. Negative correlations were evident in the right superior prefrontal cortex, and the temporoparietal junction, particularly on the right side. The pattern in single subjects was broadly similar, although individual differences in neural response were also observed. A graded relationship between symptom intensity and regional brain activity can thus be identified in obsessive-compulsive disorder. It is hypothesised that the increases in rCBF in the orbitofrontal cortex, neostriatum, global pallidus and thalamus were related to urges to perform compulsive movements, while those in the hippocampus and posterior cingulate cortex corresponded to the anxiety that accompanied them.

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Functional anatomy of obsessive-compulsive phenomena.

Neurophysiological deficits in the left dorsolateral prefrontal cortex (DLPFC) have been described in positron emission tomography studies of schizophrenia and depression. In schizophrenia and depression this deficit has been associated with the syndromes of psychomotor poverty and psychomotor retardation, respectively. Such findings lead to a prediction that DLPFC dysfunction is symptom rather than disease related. This prediction was empirically tested in a retrospective study that pooled data from 40 patients meeting research diagnostic criteria for depression and 30 patients meeting DSM-III R criteria for schizophrenia. The patients were categorised into those with and without poverty of speech, a symptom that is an observable manifestation of psychomotor impairment. The profile of regional cerebral blood flow (rCBF), measured in all subjects under resting conditions, was subsequently compared in these two groups. Patients with poverty of speech had significantly lower rCBF in the left DLFPC. This reduction of rCBF was independent of diagnosis. The findings support the view that the study of symptoms, or symptom clusters, can provide information additional to that of traditional diagnostic systems in the study of the major psychoses.

https://jnnp.bmj.com/content/jnnp/56/12/1290.full.pdf

Dorsolateral prefrontal cortex dysfunction in the major psychoses; symptom or disease specificity?

Depression with cognitive impairment, so called depressive pseudodementia, is commonly mistaken for a neurodegenerative dementia. Using positron emission tomography (PET) derived measures of regional cerebral blood flow (rCBF) a cohort of 33 patients with major depression was studied. Ten patients displayed significant and reversible cognitive impairment. The patterns of rCBF of these patients were compared with a cohort of equally depressed non-cognitively impaired depressed patients. In the depressed cognitively impaired patients a profile of rCBF abnormalities was identified consisting of decreases in the left anterior medial prefrontal cortex and increases in the cerebellar vermis. These changes were additional to those seen in depression alone and are distinct from those described in neurodegenerative dementia. The cognitive impairment seen in a proportion of depressed patients would seem to be associated with dysfunction of neural systems distinct from those implicated in depression alone or the neurodegenerative dementias.

https://jnnp.bmj.com/content/jnnp/55/9/768.full.pdf

Regional cerebral blood flow abnormalities in depressed patients with cognitive impairment.

BACKGROUND This study investigated biological correlates of depression in patients with idiopathic Parkinson's disease (PD). We tested the hypothesis that in patients with PD and depression, there was regional dysfunction involving brain areas previously implicated in functional imaging studies of patients with primary depression.

METHOD Using positron emission tomographic measurements of regional cerebral blood flow (rCBF), patterns of resting rCBF were measured in ten patients with PD and major depression, and ten patients with PD alone. The results were compared with findings from ten patients with primary depression and ten normal controls, scanned using identical methods as part of an earlier study. Groups were matched for age, sex and symptom severity.

RESULTS Bilateral decreases in rCBF were observed in anteromedial regions of the medial frontal cortex and the cingulate cortex (Brodmann's areas (BA) 9 and 32) in the depressed PD group, compared with those with PD alone and compared with normal controls. This regional disturbance overlapped that observed in patients with primary depression.

CONCLUSIONS The findings indicate that the medial prefrontal cortex is a common area of neural dysfunction in the manifestation of both primary depression and depression in PD.

Depression in Parkinson's disease. A positron emission study.

The relationship between neuropsychological test performance and regional cerebral blood flow (rCBF) was examined in 29 patients meeting Research Diagnostic Criteria (RDC) for major depression. Following a comprehensive neuropsychological assessment two subsets of tests, comprising tests that discriminated between patients and controls or between patients with varying degrees of global cognitive impairment, were selected. These subtests were entered into a principal components analysis (PCA) which generated a two-factor solution, accounting for 50% of the overall variance in test scores. Individual patient loadings on each of these factors were subsequently correlated with regional cerebral blood flow (rCBF), as measured by positron emission tomography (PET). Both factors demonstrated significant correlations with rCBF in the medial prefrontal cortex and frontal polar cortex while for each factor there were also unique patterns of correlations with posterior brain regions. The findings provide additional evidence that neuropsychological deficits in depression are associated with abnormalities in regional brain function and in particular with the function of the medial prefrontal cortex.

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C. J. Bench

Papers

Functional anatomy of obsessive-compulsive phenomena.

Dorsolateral prefrontal cortex dysfunction in the major psychoses; symptom or disease specificity?

Regional cerebral blood flow abnormalities in depressed patients with cognitive impairment.

Depression in Parkinson's disease. A positron emission study.

Neuropsychological dysfunction in depression : the relationship to regional cerebral blood flow