Visual evoked potentials relating to imagery: Words for concrete objects versus absolute concepts

Summary We recorded visual evoked potentials (VEPs) elicited with high or low imaginable Chinese characters (HIC or LIC), representing concrete objects or absolute concepts, respectively. A closed circle (CC) acts as control stimulus. These were displayed (at 1.6° visual angle) for 35 ms on a TV monitor. Twenty-one channel VEPs (band-pas filter: 0.05–60 Hz), using balanced non-cephalic electrodes, were recorded from –100 to 924 ms for 11 right-handed male volunteers. The VEPs were analyzed by multivariate analysis of variance (MANOVA) and comparison of topographies at four remarkable peaks (P110, N160, P230 and N320). MANOVA showed significant differences (p< 0.001) for both conditions of channel and stimuli (HIC, LIC or CC). P100 for the CC-VEPs, N160 for the HIC-and LIC-VEPs, P230 for the CC-VEPs, and N320 for the HIC-VEPs were remarkable in the posterior scalp regions. Topographies at P100 and N160 showed no difference between the HIC-and LIC-stimuli. However, those at N320 showed difference between the HIC-and LIC-stimuli over the occipital and posterior temporal areas. Those results suggest that the responses at P100 and N160 might segregate Chinese characters from non Chinese characters. N320 suggested certain processes in imagery on recognizing Chinese characters over the occipital and posterior temporal areas.We are grateful to Dr. Yoshiji Kojima of Hamamatsu University for helpful comments.     

Internal and external information processing by lateral hypothalamic glucose-sensitive and insensitive neurons during bar press feeding in the monkey

Single neuron activities in the lateral hypothalamic area (LHA) were recorded during bar press feeding task in the monkey. First registered neurons were sorted into 2 groups, glucose-sensitive (GS) and glucose-insensitive (GIS) neurons, depending on their glucose sensitivity. Then firing variations to feeding, electrophoretically applied catecholamines and opiate, and to odor and taste stimuli were investigated. GS neurons responded to dopamine, noradrenaline and morphine more often than GIS neurons. In feeding task GS neurons responded during bar press (BP) and reward (RW) periods with long-lasting inhibition of firing and at cue tone (CT) with transient inhibition, while GIS neurons responded during BP and RW periods mainly with excitation and at cue light (CL) with excitation. A majority of GS neurons responded to both odor and taste stimuli more often than GIS neurons. Data suggest that these two kinds of neurons in the LHA may be involved in different functional aspects of feeding: GS neurons, mainly in internal information processing and reward mechanism, and GIS neurons, in external information processing and motor aspects.     

Involvement of phosphoinositide metabolism in GABA-induced catecholamine release from cultured bovine adrenal chromaffin cells

The effects of GABA on catecholamine release and phosphoinositide metabolism were studied in cultured bovine adrenal chromaffin cells. GABA and muscimol, a specific agonist for the GABAA receptor, each evoked a gradual secretion of catecholamines from the cells in the presence of ouabain, an inhibitor of Na+, K(+)-ATPase. This release was inhibited by bicuculline, a specific antagonist for the GABAA receptor, or by picrotoxin, a blocker of GABA-gated Cl- channels, and was potentiated by diazepam or pentobarbital. GABA or muscimol induced a concentration-dependent formation of inositol phosphates. This accumulation of inositol phosphates was also inhibited by bicuculline, picrotoxin or removal of extracellular Ca2+, and also potentiated by diazepam and pentobarbital. Nicardipine suppressed GABA-induced catecholamine release in the presence of ouabain and accumulation of inositol phosphates, while verapamil, diltiazem, and omega-conotoxin failed to inhibit these responses to GABA. The phosphoinositide-specific phospholipase C inhibitor neomycin also inhibited both GABA-induced accumulation of inositol phosphates and stimulation of catecholamine release in the presence of ouabain. These results taken together indicate that GABA evoked catecholamine release from the chromaffin cells in the presence of ouabain by stimulation of phosphoinositide metabolism in a Ca2(+)-sensitive manner via activation of GABAA receptor-coupled Cl- channels.     

Bipedicle flap reconstruction for complex longitudinal dorsal tissue defects of the digits

Achieving coverage after digital injury is crucial, because simple skin defects can expose essential structures such as tendons or bones. This is particularly true on the dorsal surfaces of the digits, where the skin provides the only protection for the tendons. However, longitudinal skin defects of the digit have not been specifically identified in the literature and there have been few reports focusing on longitudinal dorsal skin defects. Here we report on the use of a bipedicle flap for reconstruction of complex longitudinal dorsal tissue defects of the digits, including those associated with tendon or bone damage.