Changing Brain Functions

Abstract This chapter examines events and technologies that can change brain function. The chapter surveys four types of brain changes that are likely to appear in legal contexts: brain injury, psychoactive drug effects, surgery, and electromagnetic stimulation. The chapter discusses the differing effects of brain damage that is localized (like a penetrating gunshot), diffuse (like a traumatic brain injury from a blow to the head), or something intermediate (like a stroke). The chapter reviews the effects of psychoactive drugs such as anesthetics, analgesics, antidepressants, antipsychotics, cannabis, hallucinogens, narcotics, sedatives, and stimulants. The chapter then covers three of the most common electromagnetic human brain manipulation technologies: deep brain stimulation (DBS), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS). The latter two technologies can be used to modulate parts of the brain close to the skull, temporarily activating or deactivating them.