5-HT2A is a serotonin receptor. 5-HT2A is not a classic cannabinoid receptor but its activity is modulated by cannabinoids. Since cannabinoids have a physiological effect on 5-HT2A it is effectively a cannabinoid receptor.
5-HT2A is expressed widely throughout the central nervous system. It is expressed near most of the serotoninergic terminal rich areas, including neocortex (mainly prefrontal, parietal, and somatosensory cortex) and the olfactory tubercle. Especially high concentrations of this receptor on the apical dendrites of pyramidal cells in layer V of the cortex may modulate cognitive processes, working memory,and attention.
Russo, E.B., Burnett, A., Hall, B., and Parker, K.K. (2005). Agonistic properties of cannabidiol at 5-HT1A receptors. Neurochem. Res. 30, 1037–1043.