Inclusion criteria used to select the healthy scuba divers
| No diagnosis of depression |
| No psychiatric disease |
| No neurological disease |
| No current use of the following medication: |
| Antipsychotic |
| Antidepressant |
| Anticonvulsant |
| Antiparkinson |
| Antidiabetics |
| Narcotics |
| Methyldopa |
| Clonidine |
| Diamox |
| Hydergine |
| Cognitive enhancing medication |
| No blindness |
| No diabetes |
| No hypertension |
| No vascular disease |
| No artheriosclerosis |
| No history of decompression illness |