PSYC 210 Lecture Notes - Lecture 2: Seasonal Affective Disorder, Paraventricular Nucleus Of Hypothalamus, Light Therapy
30 Mar 2017
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Document Summary
Infradian more than a day, menstrual cycle. Ultradian less than a day, meals, sleep cycles. Zeitgeber cues that synchronize biological rhythms (i. e. sunlight) Entrainment the process of synchronizing a biological rhythm. Jet lag: caused by circadian rhythm being disrupted. Circadian rhythm: free running rhythm, body rhythm in the absence of external cues, human free running period is less than 24 hours. Neural mechanism: the retinohypothalamic tract light signal (zeitgeber) is transmitted from rgc to the suprachiasmatic nucleus of the hypothalamus. The retinohypothalamic tract: photic info for scn is neither rods/cones, melanopsin intrinsically photosensitive retinal ganglion cells (iprgcs) Non-image forming function: loss of iprgcs exhibit free running reason. Neural mechanisms: suprachiasmatic nucleus (scn) master biological clock, intrinsic rhythm in the scn more active during light period, individual scn neuron fires rhythmically in a tissue culture. Lesions of the scn lead to arrhythmic animal. Transplants of embryonic scn cells restore the circadian rhythm. Circannual rhythm: controlled by day length, pineal gland.
