eyes. In the control group, the cortex was activated when looking at the photos, and less active when the participant closed his eyes; however, under the influence of ayahuasca and DMT, even with closed eyes, the cortex was just as active as when looking at the photographs. This study suggests that ayahuasca activates a complicated network of vision and memory which heightens the internal reality of the participants. It is claimed that people may experience profound positive life changes subsequent to consuming ayahuasca, by author Don Jose Campos and others. Vomiting can follow ayahuasca ingestion; this is considered by many shamans and experienced users of ayahuasca to be a purging and an essential part of the experience, representing the release of negative energy and emotions built up over the course of one's life. Others report purging in the form of diarrhea and hot/cold flashes. The ingestion of ayahuasca can also cause significant but temporary emotional and psychological distress. Excessive use could possibly lead to serotonin syndrome (although serotonin syndrome has never been specifically caused by ayahuasca except in conjunction with certain anti-depressants like SSRIs). Depending on dosage, the temporary non-entheogenic effects of ayahuasca can include tremors, nausea, vomiting, diarrhea, autonomic instability, hyperthermia, sweating, motor function impairment, sedation, relaxation, vertigo, dizziness, and muscle spasms which are primarily caused by the harmala alkaloids in ayahuasca. Long-term negative effects are not known. A few deaths linked to participation in the consumption of ayahuasca have been reported. Some of the deaths may have been due to unscreened preexisting heart conditions, interaction with drugs, such as antidepressants, recreational drugs, caffeine (due to the CYP1A2 inhibition of the harmala alkaloids), nicotine (from drinking tobacco tea for purging/cleansing), or from improper/irresponsible use due to behavioral risks or possible drug to drug interactions. Potential therapeutic effects There are potential antidepressant and anxiolytic effects of ayahuasca. For example, in 2018 it was reported that a single dose of ayahuasca significantly reduced symptoms of treatment-resistant depression in a small placebo-controlled trial. More specifically, statistically significant reductions of up to 82% in depressive scores were observed between baseline and 1, 7 and 21 days after ayahuasca administration, as measured on the Hamilton Rating Scale for Depression (HAM-D), the Montgomery-Åsberg Depression Rating Scale (MADRS), and the Anxious-Depression subscale of the Brief Psychiatric Rating Scale (BPRS). Other placebo-controlled research has provided evidence that ayahuasca can help improve self-perceptions in those with social anxiety