Neuropeptide Y in the Adult and Fetal Human Pineal Gland

Neuropeptide Y was isolated from the porcine brain in 1982 and shown to be colocalized with noradrenaline in sympathetic nerve terminals. The peptide has been demonstrated to be present in sympathetic nerve fibers innervating the pineal gland in many mammalian species. In this investigation, we show by use of immunohistochemistry that neuropeptide Y is present in nerve fibers of the adult human pineal gland. The fibers are classical neuropeptidergic fibers endowed with largeboutons en passageand primarily located in a perifollicular position with some fibers entering the pineal parenchyma inside the follicle. The distance from the immunoreactive terminals to the pinealocytes indicates a modulatory function of neuropeptide Y for pineal physiology. Some of the immunoreactive fibers might originate from neurons located in the brain and be a part of the central innervation of the pineal gland. In a series of human fetuses, neuropeptide Y-containing nerve fibers was present and could be detected as early as in the pineal of four- to five-month-old fetuses. This early innervation of the human pineal is different from most rodents, where the innervation starts postnatally.

Dissociative Experiences and Reality-Testing Deficits in College Students

One hundred forty-one college students completed a computerized test of reality-monitoring deficits and a computerized version of the Dissociative Experiences Scale (DES). In the test of reality-monitoring, subjects fixated on a dot, perceived a stimulus to one side, imaged an identical stimulus on the other side and rated its vividness while continuing to image. Then, either the dot became a P and subjects pressed a button on the side of the percept, as quickly as possible, or the dot became an I and subjects pressed a button on the side of the image. Subjects exhibiting above-median scores on the Dissociation/Amnesia factor of the DES took longer to discriminate perception from vivid imagery than from faint imagery, as if they failed to monitor the greater “central innervation” behind more vivid, more percept-like imagery. These results corroborate recent findings that dissociative tendencies in college students, like psychotic tendencies in students, have reality-testing deficiencies at their core.

Personality Traits and Reality-Testing Abilities, Controlling for Vividness of Imagery

One hundred seventy-seven college students completed personality measures including the MMPI-168, and reality-discrimination measures including a timed discrimination task developed by the first author. Previously on such a timed task, normal subjects discriminated percepts more quickly from images of perceptual vividness than from faint images, as if they registered more “central innervation” during more vivid imaging. Presently, on each of the four practice trials and forty-four timed trials in Task 1, subjects fixated on a dot, perceived a stimulus to one side, imaged an identical stimulus on the other side and rated its vividness while continuing to image. Then, either the dot became a P and subjects pressed a button on the side of the percept, as quickly as possible, or the dot became an I and subjects pressed a button on the side of the image. The slope, within subject, of image/percept discrimination times over image-vividness ratings was computed for the 149 subjects who rated some of their forty-four images more vividly than others. It was predicted and found that self-described hallucinators and MMPI-defined paranoids discriminated percepts less quickly from vivid images, as if the greater “central innervation” behind more vivid images is not registered by psychosis-prone subjects.