[Impairment of social cognition in Parkinson disease--comparison of idiopathic Parkinson disease with juvenile parkinsonism].

The degeneration of mesocorticolimbic dopaminergic system is assumed to disturbed motivated behavior, intellectual impairment and depression in Parkinson's disease (PD), and there is growing interest in its role in impaired emotional and social behaviors. Patients with PD demonstrated the impairment of social cognition by the test of facial expression recognition and the Iowa gambling task (IGT). However, the result of facial expressions cognition in patients with juvenile parkinsonism (JP) is not significantly different from normal controls. In the IGT, the JP group learned better performance than the PD group. The relatively spared social cognition in JP as compared with PD could be attributed that dopaminergic depletion being more severe in the nigrostriatal system than in the mesocorticolimbic system.

Relatively spared mesocorticolimbic dopaminergic system in juvenile parkinsonism.

This study aims to examine the function of the mesocorticolimbic dopaminergic system, including the amygdala, in recognizing emotions in juvenile parkinsonism (JP). Eleven patients with JP and 16 age-matched controls selected one basic emotion (happiness, sadness, anger, fear, surprise, or disgust) that best described the emotional state represented by visual and auditory stimuli. There was no significant difference between the patients and normal controls in their recognition of emotions. The spared emotion recognition in JP could be attributed to the absence of any pathological changes or the normal dopamine concentrations in the mesocorticolimbic system in this condition.

Impairment of odor recognition in Parkinson's disease caused by weak activations of the orbitofrontal cortex.

Olfactory dysfunction and abnormalities of olfactory brain structures are found in patients with Parkinson's disease (PD), and a number of studies have reported that olfactory dysfunction is caused by abnormalities of the central olfactory systems. We previously analyzed electroencephalograms (EEGs) and respiration simultaneously in normal subjects while testing for detection and recognition of odors. We identified changes in respiration pattern in response to odor stimuli and found inspiratory phase-locked alpha oscillations (I-alpha). The genesis of I-alpha were identified in olfactory-related areas including the entorhinal cortex, hippocampus, amygdale and orbitofrontal cortex with an EEG dipole tracing method. In the present study, we used the same protocol in PD patients and compared results of PD with those of age-matched controls. All PD patients detected odor, but 5 out of 10 showed impaired odor recognition. Changes in breathing pattern associated with emotional changes during exposure to odor stimuli were not observed in PD patients. I-alpha waveforms were not observed; however, positive waves followed by negative waves were identified approximately 100ms after inspiration onset. Dipoles of this component were localized in the entorhinal cortex for odor detection in all patients and in the entorhinal cortex and middle temporal gyrus for PD patients who could discriminate odors. Odor recognition in PD could be subserved by a different neural circuit from that of normal subjects, done through the temporal association cortex as a subsystem for recognizing the odor; however, the system may not be associated with the odor-induced emotions.

[Impairment of social cognition in Parkinson's disease].

The characteristic four symptoms of motor deficits, bradykinesia, rigidity, resting tremor and impairment of postural reflex with Parkinson's disease (PD) are accompanied by specific cognitive deficits. Deficits of executive functions, skill learning, and visuospatial cognition are well known. The results of our recent studies show the deficit of social cognition which include facial expression recognition, sensation of gaze direction, "theory of mind" in comprehension, and decision making. These symptoms can be explained by the damage of the amygdala and/or its connection, which are known to play a crucial role in social cognition, it is attributed to the involvement of amygdala and it's connection to the frontal lobe in PD. The impairment of social cognition is an important mental change associated with PD.

[A case of topographic disorientation without right occipital lesion].

A 73-year-old right-handed man developed topographical disorientation, left homonymous hemiianopsia, left visuospatial neglect and mild visual memory disturbance following the right hemispheric infarction. The visual agnosia is very similar to agnosia for streets because he could not identify familiar buildings and streets even though he could remember their way. He did not have prosopagnosia. His brain MRI demonstrated infarction at the right anterior choroidal artery area, including right thalamus, caudate tail and optic radiation. SPECT showed the mild decrease of rCBF at the right temporoparietal cortex. His topographic disorientation faded and finally disappeared about 3 weeks after its onset. Our case is atypical because of sparing the posterior part of the right parahippocampal gyrus where plays an important role in the development of agnosia for streets.