抄録
Higher intelligent behaviors of humans consist of various neuropsychological elements. Among them, amodal imagery without overt sensory input and/or motor output is important for simulating the real world in mind. A series of our human noninvasive studies with combined techniques of functional magnetic resonance imaging and repetitive transcranial magnetic stimulation show that the rostral part of the premotor cortex (Brodmann area 6), which is situated between the prefrontal cortex and primary motor area and often regarded as the bridge between cognition and motor control, plays a key role in mental-operation without overt motor control. In addition, the medial and lateral part of the rostral premotor cortex is functionally specialized for different cognitive functions likewise for motor functions. The medial premotor cortex is relevant for internally generated sequential operation of abstract representation, whereas the lateral premotor cortex is closely related to spatial manipulation of concrete representation. As a common computational process shared by the motor and cognitive behaviors in these regions, we envisage functions to simulate the outcome of rule-based operations. If an arbitrary stimulus-to-response linkage function of the premotor cortex could cover a response output to the memory system instead of overt motor execution, identical control principles could apply more widely to nonmotor executive behaviors. [Jpn J Physiol 54 Suppl:S14 (2004)]
