The Lateral Occipito-temporal Cortex Is Involved in the Mental Manipulation of Body Part Imagery.

The lateral occipito-temporal cortex (LOTC), including the extrastriate body area, is known to be involved in the perception of body parts. Although still controversial, recent studies have demonstrated the role of the LOTC in higher-level body-related cognition in humans. This study consisted of two experiments (E1 and E2). The first (E1) was an exploratory experiment to find the neural correlate of the mental manipulation of body part imagery, in which brain cerebral glucose metabolic rates and the performance of mental rotation of the hand were measured in 100 subjects who exhibited a range of symptoms of cognitive decline. In E1, we found that the level of glucose metabolism in the right LOTC was significantly correlated with performance in a task involving mental manipulation of the hand. Next, in E2, we performed a randomized, double-blind, controlled intervention study (clinical trial number: UMIN 000018310) in younger healthy adults to test whether right occipital (corresponding to the right LOTC) anodal stimulation using transcranial direct current stimulation (tDCS) could enhance the mental manipulation of the hand. In E2, we demonstrated a significant effect of tDCS on the accuracy rate in a task involving mental manipulation of the hand. Although further study is necessary to answer the question of whether these results are specific for the mental manipulation of body parts but not non-body parts, E1 demonstrated a possible role of the LOTC in carrying out the body mental manipulation task in patients with dementia, and E2 suggested the possible effect of tDCS on this task in healthy subjects.

The Possible Link between GABAergic Dysfunction and Cognitive Decline in a Patient with Idiopathic Hypoparathyroidism.

Idiopathic hypoparathyroidism (IHP) is accompanied by cognitive impairment. We report the case of a 70-year-old IHP patient with cognitive disturbance. Brain computed tomography showed bilateral calcification in basal ganglia, thalamus, and cerebellum. Neuropsychological assessment revealed low scores for intelligence, memory, and perseverative errors. Brain positron emission tomography showed a significant reduction in [(18)F]-Fludeoxyglucose (FDG) uptake in bilateral frontal, left temporal and parietal cortices, along with a marked reduction in [(11)C]-flumazenil binding in left frontal, temporal, parietal, and bilateral cerebellum. These findings suggest cognitive impairment in IHP may be ascribed to GABAergic dysfunction, thus leading to, or coexisting with, cerebral hypometabolism.

Changes in cerebral blood flow under the prone condition with and without massage.

To investigate changes in regional cerebral blood flow (rCBF) under the prone condition with and without light massage on the back, we measured rCBF quantitatively in healthy human subjects using positron emission tomography with H(2)15O. Biochemical tests showed that the light massage (palm-pressure) reduced levels of stress-related serum cortisol and salivary stress protein chromogranin-A measured after the PET examination. Absolute rCBF significantly increased in the parietal cortex (precuneus) under the prone condition compared with the supine condition, and this rCBF increase was in parallel with comfortable sensation and slowing heart rate during the massage. Correlation analysis in statistical parametric mapping showed that the amygdalar and basal forebrain rCBF correlated with parasympathetic function (heart rate reduction), indicating involvement of the forebrain-amygdala system in mediating activities in the autonomic nervous system in the presence of comfortable sensation. To conclude, prone posture itself can stimulate the precuneus region to raise awareness, and the light massage on the back may help accommodate the brain to comfortable stimulation.