Abstract
This article reviews the current understanding of the mechanisms underlying judgment and behavior, and the clinical conditions characterized by abnormal judgment and behavior. Judgment is divided into two categories : cognitive judgment and social judgment. Cognitive judgment is directly related to the perception and recognition of external stimulus and internal milieu whereas social judgment involves interpersonal relationship. For the cognitive judgment of general sensory information, the primary as well as secondary sensory center for each modality plays a role. For special sensory modalities, special receptive areas in the parietal and temporal cortices are important. Examples of the areas where these special sensory judgments take place include area V5 at the posterior temporal cortex for visual motion, the fusiform gyrus for face recognition, the amygdala for face emotion, the left parietal cortex for body image, and area 31 at the mesial parietal lobe for geographic information processing. Regarding social judgment, the orbitofrontal cortex and the dorsolateral prefrontal area are important for the social judgment of visual input, the amygdala for face emotion, and the mesial prefrontal area for moral judgment.
Behavior is classified into three categories : reflex, impulsive and planned. For the reflex action/behavior, the superior colliculus is involved in the reaction to visual input, the brainstem reticular formation to acoustic input, and the periaqueductal grey matter to nociceptive input. Regarding impulsive behavior, an increasing attention has been paid to the impulse control disorders such as pathological gambling and punding, which are seen in patients with Parkinson disease during a long-term L-dopa treatment. The ventral striatum and the dopaminergic mesolimbic system are related to reward and motivation, drug abuse and the impulse control disorders. As for the planned action/behavior, a slowly rising surface negative electric potential preceding voluntary movement (Bereitschaftspotential, BP) has drawn the attention of many investigators since its discovery by Kornhuber and Deecke in 1965. Now BP associated with self-paced, simple movement of unilateral hand is believed to be generated first in the pre-supplementary motor area (pre-SMA) and the SMA proper bilaterally, followed by the lateral premotor area more contralaterally, and finally the contralateral primary motor area. For the complex movement used in daily life, the parietal cortex on the dominant hemisphere is activated before the sensorimotor cortices. However, the question as to where in the brain and when the conscious will to move occurs still remains to be elucidated.
