It has been hypothesized that a decrease in dopaminergic presynaptic activity during abstinence or withdrawal is related to relapse in cocaine-dependent subjects (Dackis and Gold 1985;Markou and Koob 1991). This study measured striatal Cocaine is one of the most potent and reinforcing central nervous system stimulants (Withers et al. 1995). Cocaine's pharmacological effects are due to its binding of the dopamine transporter molecule, thereby increasing intrasynaptic dopamine concentration (Giros et al. 1996). Seventy-five percent of patients who withdraw from cocaine abuse relapse within a year (Paredes et al. 1991;Carroll et al. 1994 Gawin and Kleber (1986), Martin et al. (1989a), andSatel et al. (1991) found that there was a delayed cocaine craving with approximately 10 days of abstinence from cocaine. Gawin and Kleber (1986) have described a triphasic course during abstinence from cocaine for outpatients. The first phase is described as a crash phase with extreme dysphoria and hypersomnolence lasting 1 to 40 h. The second phase is described as the withdrawal period lasting up to 10 weeks. This phase is subdivided into two subphases. The early subphase is characterized initially by little cocaine craving, nearnormal affective functioning, and normal sleep/wake cycles, and it lasts several days. The middle and late subphase is characterized by high cocaine craving, dysphoria, anhedonia, and anxiety and sensitivity to conditioned cues. Martin et al. (1989a) found that there was distinct increase in cocaine craving between 1 and 2 weeks after last cocaine use in six patients who were evaluated over a 21-day period during an inpatient recovery. Satel et al. (1991) found that there was an initial decrease in Beck Depression score between days 1-9

Muscle responses (MEPs) to transcranial electrical stimulation were studied in 7 patients with apallic syndrome. All the patients showed clinical signs of upper motor neurone impairment in the upper and lower limbs. MEPs were absent or markedly delayed in 4 of the 7 patients. Since patients with apallic syndrome show only minimal voluntary movement, transcranial stimulation is the only way to demonstrate abnormalities of fast corticospinal axons in these patients. Even though these patients often look similar clinically, with tetraplegia and decorticate or decerebrate posture, only some cases showed dysfunction of fast corticospinal neurons.

Current digital communication technologies used to monitor ART adherence include electronic adherence monitors (EAMs), digital ingestion monitors, cellular phones, and electronic pharmacy refill tracking systems. Currently available real-time adherence monitoring approaches based on cellular technology allow for the delivery of interventions precisely when and where they are needed. Such technology can potentially enable significant efficiency of care delivery and impact on adherence and associated clinical outcomes. Standard digital advances, such as automated reminders in EAM and electronic pharmacy records, may also achieve improvements with relatively lower cost and easier implementation. Future research is needed to improve the functionality of these approaches, with attention paid to system-level issues through implementation science, as well as acceptability and ethical considerations at the individual level.