The structure of the brain mainly includes the cerebral hemispheres, brainstem, cerebellum and mesencephalon. The cerebral hemispheres are separated by the longitudinal fissure into left and right symmetrical hemispheres, connected by the corpus callosum. The cerebral hemisphere includes the cerebral cortex, white matter, basal ganglia and lateral ventricles. The cerebral cortex is divided into frontal, temporal, parietal and occipital lobes, and also includes the insula deep in the lateral fissure of the brain and the limbic lobe, which includes the cingulate gyrus, hippocampal gyrus and hook gyrus. The brain stem mainly includes the pontocerebrum, medulla oblongata and midbrain, the cerebellum generally includes both cerebellar hemispheres and the middle cerebellar tonsils, and the mesencephalon includes the thalamus, superior thalamus, hypothalamus and basal thalamus.