The lobe involved in the regulation of sexual behaviour and expression of emotional reaction is the 'limbic lobe'. It is formed by the inner part of the cerebral hemispheres and structures like the amygdala, hippocampus, etc. Hence, it is a part of the forebrain.
The forebrain consists of the hypothalamus, thalamus, and cerebrum.
The layer of cells covering cerebral hemispheres is the cerebral cortex, also called grey matter.
Association areas of the forebrain are neither motor nor sensory in function.