Two types of field potentials were identified in cat visual cortex using contrast reversal of oriented bar gratings: a short-latency fast-local component with a retinotopic organization similar to that seen with single-unit discharges at the same cortical site, and a slow, nonretinotopic component with a longer peak latency. The slow-distributed component had an extensive receptive field mapped by measuring the amplitude of binary kernels and showed strong inhibitory interactions within the receptive field. The peak latency of the slow-local component increased with distance from the retinotopic center, suggesting a possible conduction delay. Both components showed some orientation bias depending on the laminar location, but the bias could be independent of the orientation preferred by single units in the immediate vicinity. The present findings indicate that locally generated field potentials reflect cortical mechanisms for nonlinear integration over wide areas of the visual field.

A 57-year-old male with primary intracranial malignant melanoma who survived 9 years and 6 months is reported. He underwent surgical removal of the tumour three times during the decade 1978 to 1988, and received chemo-immuno-radiotherapy during that time. Acute tumour growth, suggesting tumour dissemination, was seen in the CT scans after the third removal of recurrent tumour, but then it disappeared after combined chemoradiotherapy with DTIC. He gradually became inactive, probably because of brain atrophy caused by high-dose radiotherapy and chemotherapy, and died of renal failure without any sign of recurrence on CT scans.

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The effect of dopamine during barbiturate therapy was investigated in 29 cats including 5 sham-operated cats. According to Kiersey's classification of electro-encephalographic patterns, physiological variables, cerebral metabolic rates for oxygen and glucose, cerebral blood flow (CBF), and intracranial pressure (ICP), etc. were evaluated in each electro-encephalographic pattern. Oxygen-glucose index was calculated and used as an indicator for aerobic or anaerobic metabolism of glucose. Group 1 (12 cats), to which only thiamylal was administered, maintained aerobic glycolysis due to a parallel reduction of cerebral metabolic rates for oxygen and glucose (about half of the initial value at Kiersey's fifth pattern) in spite of reduction of CBF and mean arterial blood pressure (MABP). Group 2 (12 cats), to which dopamine was administered in addition to thiamylal due to a reduction of MABP, showed anaerobic glycolysis though MABP and CBF were maintained. These findings are ascribed to an increase of cerebral metabolic rate for glucose up to 130% of the initial value though cerebral metabolic rate for oxygen decreased down to half of the initial value: The beneficial effect of barbiturate on cerebral metabolism was reduced by use of dopamine. ICP was reduced in both groups. Our result indicates that administration of extracellular fluid may be preferable for treatment of hypotension during barbiturate therapy than dopamine medication.