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What catatonia can tell us about "top-down modulation": A neuropsychiatric hypothesis

Northoff, Georg (2002) What catatonia can tell us about "top-down modulation": A neuropsychiatric hypothesis.

Short Abstract:

Differentialdiagnosis of motor symptoms, as for example akinesia, may be difficult in clinical neuropsychiatry. They may be either of neurologic origin, as for example Parkinson's disease, or psychiatric origin, as for example catatonia, leading to a so-called "conflict of paradigms". Despite their different origin symptoms may appear clinically more or less similar. Possibility of dissociation between origin and clinical appearance may reflect functional brain organisation in general and cortical-cortical/subcortical relations in particular. It is therefore hypothesized that similarities and differences between Parkinson's disease and catatonia may be accounted for by distinct kinds of modulation between cortico-cortical and cortico-subcortical relations. Comparison between Parkinson's disease and catatonia reveals distinction between two kinds of modulation "vertical and horizontal modulation". "Vertical modulation" concerns cortical-subcortical relations and allows apparently for bidirectional modulation. This is reflected in possibility of both "top-down and bottom-up modulation" and appearance of motor symptoms in both Parkinson's disease and catatonia. "Horizontal modulation" concerns cortical-cortical relations and allows apparently only for unidirectional modulation. This is reflected in one-way connections from prefrontal cortex to motor cortex and absence of major affective and behavioural symptoms in Parkinson's disease. It is concluded that comparison between Parkinson's disease and catatonia may reveal the nature of modulation of cortico-cortical and cortico-subcortical relations in further detail.

Long Abstract:

Differentialdiagnosis of motor symptoms, as for example akinesia, may be difficult in clinical neuropsychiatry. They may be either of neurologic origin, as for example Parkinson's disease, or psychiatric origin, as for example catatonia, leading to a so-called "conflict of paradigms". Despite their different origin symptoms may appear clinically more or less similar. Possibility of dissociation between origin and clinical appearance may reflect functional brain organisation in general and cortical-cortical/subcortical relations in particular. It is therefore hypothesized that similarities and differences between Parkinson's disease and catatonia may be accounted for by distinct kinds of modulation between cortico-cortical and cortico-subcortical relations. Catatonia can be characterized by concurrent motor, emotional and behavioral symptoms. These different symptoms may be accounted for by dysfunction in orbitofrontal-prefrontal/parietal cortical connectivity reflecting "horizontal modulation" of cortico-cortical relation. Furthermore alteration in "top-down modulation" reflecting "vertical modulation" of caudate and other basal ganglia by gaba-ergic mediated orbitofrontal cortical deficits may account for motor symptoms in catatonia. Parkinson' disease in contrast can be characterized by predominant motor symptoms. Motor symptoms may be accounted for by altered "bottom-up modulation" between dopaminergic mediated deficits in striatum and premotor/motor cortex. Clinical similarities between Parkinson's disease and catatonia with respect to akinesia may be related with involvement of the basal ganglia in both disorders. Clinical differences with respect to emotional and behavioural symptoms may be related with involvement of different cortical areas i.e. orbitofrontal/parietal and premotor/motor cortex implying distinct kinds of modulation i.e. "vertical and horizontal modulation" respectively. Comparison between Parkinson's disease and catatonia reveals distinction between two kinds of modulation "vertical and horizontal modulation". "Vertical modulation" concerns cortical-subcortical relations and allows apparently for bidirectional modulation. This is reflected in possibility of both "top-down and bottom-up modulation" and appearance of motor symptoms in both Parkinson's disease and catatonia. "Horizontal modulation" concerns cortical-cortical relations and allows apparently only for unidirectional modulation. This is reflected in one-way connections from prefrontal to motor cortex and absence of major affective and behavioural symptoms in Parkinson's disease. It is concluded that comparison between Parkinson's disease and catatonia may reveal the nature of modulation of cortico-cortical and cortico-subcortical relations in further detail.