| Budget Amount *help |
¥4,210,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥810,000)
Fiscal Year 2007: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
Cognitive functions of non-spatial visual processing were examined at the single neuron level in the monkey cingulate cortex. Monkeys were trained to perform a pictorial fixation (PICT) task, in which various kinds of colored pictures of faces and other objects were presented while they fixate on a central target. A recording cylinder was placed over the opening made in the skull overlying the cingulate cortical region. After recovery from the surgery, extracellular unit recording was performed while the monkeys perform the task. All of 708 neurons were recorded from the left hemisphere of two monkeys during the performance of the PICT task. Approximately 25% (n = 174) of the cingulate neurons exhibited their firing rate changes in relation to the PICT task and, moreover, about half (n = 85) of the 174 cingulate neurons were selectively responsive to attributes (e.g., shape, color) of objects and faces presented in the PICT task. The object/face-selective neurons exhibited their respon
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se preference to varying degrees; some neurons responded only to a few stimuli but not to other stimuli presented to the monkeys, while other neurons preferentially responded to several objects/faces. The object/face-related neurons mostly modified their firing rates in relation to the shape, pattern and color of the objects/faces but little did in relation to their size. We often observed that the object/face-selective neurons exhibited bursts followed by inhibitory responses. A subset of the object/face-selective neurons showed persistent excitatory activity during the stimulus presentation, and exhibited excitatory or inhibitory responses after the stimulus presentation. Neurons changing their discharging rate in relation to the PICT task were widely distributed in the cingulate cortex, whereas object/face-selective neurons were localized only in the anterior cingulate cortex. Object/face-selective responsive neurons were found also in the inferior prefrontal convexity ventral to the principal sulcus, the inferior temporal cortex, and the medial portion of the mediodorsal thalamic nucleus. The four cortical and subcortical subdivisions, therefore, could constitute the neural circuits that are involved in the processing of nonspatial visual information. Less
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