Rhythms of the Brain - Mind, Brain and Behaviour - Lecture Slides, Slides of Human ethology

Download Rhythms of the Brain - Mind, Brain and Behaviour - Lecture Slides and more Slides Human ethology in PDF only on Docsity! Rhythms of the Brain Docsity.com Types of Rhythms Ci di fl d ilrca an – uctuate a y Sleep-wake, temperature, hormones, urine production gastrointestinal activity , Cognitive and motor performance levels Infradian less than once a day– Hibernation, ovulation Ult di th dra an – more an once a ay Sleep cycles (REM and other sleep stages) Docsity.com Three Steps to Regulation Input – senses light or temperature. Pacemaker – generates and regulates the rhythm – e.g., thalamic pacemaker. Also, rhythmic activity may arise from the collective behavior of inhibitory and excitatory neurons. Output – permits pacemaker to affect tissues and organs. Docsity.com Bird Biological Clock I i l l d i bi d dnput = p nea g an – n r s an some animals, located at the top of the skull to sense light changes . Pacemaker – tryptophan is converted to melatonin (same process as serotonin) . N-acetyltransferase is key to this process Output melatonin released to bloodstream to = affect organs. Docsity.com Human Biological Clock Pineal gland unimportant to humans, but melatonin may be important. Information about light comes directly from the retina to the suprachiasmatic nucleus (SCN) in the hypothalamus. SCNs generate rhythms (spontaneous firing). Docsity.com Sleep A dil ibl f d d rea y revers e state o re uce responsiveness to, and interaction with, the environment. Lack of sleep produces unpleasant symptoms. I it bilit i i d f itirr a y, mpa re per ormance on cogn ve tasks, no lasting effects on physical health. Sleep debt Why we sleep: Restoration or adaptation? Docsity.com Human Sleep-Wake Cycles U i d i d i h dr ne pro uct on ecreases at n g t ue to fluctuations in vasopressin. Sleep occurs instantaneously not gradually , . Different people need different amounts of sleep. -- no obvious relation to mental or physical activity. Free of environmental cues (free running) people adhere to a 24.8 hr day – mutant hamsters. Jet lag occurs when sleep-wake cycles are out of phase with environment. Change to local schedule immediately Docsity.com How Long People Sleep B d i hi h i h fo y temperature s g est n t e a ternoon when people are active. P l l h b d i leop e s eep w en o y temperature s ow and wake when it is high. G i l h b d i hi ho ng to s eep w en o y temperature s g results in longer sleeping times. F li “d ll” l f d h i iee ng u resu ts rom esync ron zat on of sleep cycles. Docsity.com Stages (Cont.) N REM lon- s eep: Less dreaming Ability to move muscles Sympathetic ANS inactive No impact on learning with deprivation REM sleep: Most dreaming Atonia – inability to move muscles Sympathetic ANS active Learning is affected by deprivation Docsity.com Control of Sleep Cycles Diff d l l l duse mo u atory systems contro s eep an waking (locus coeruleus). Al t l th l t h i b iso con ro a amus o sync ron ze ra n waves during sleep. NE and Serotonin active during waking enhance activity. Different ACh neurons active in Pons during REM sleep. Docsity.com Control of Sleep (Cont.) Sl l d h h f h h leep-re ate r yt ms rom t e t a amus block sensory information to the cortex. A i i i d di d lct v ty n escen ng mo u atory systems inhibits motor neurons during dreaming (REM sleep) . Sleep-promoting substances in blood related to immune system stimulation this is why – we sleep more when sick. Docsity.com Epileptic Seizures E h b h i i hi hxtreme sync ronous e av or n w c many neurons fire at once. L li d l b loca ze or g o a Upsets balance of excitation and inhibition among neurons Anticonvulsants – drugs that counter excitability of neurons . Convulsants – drugs that block GABA. Docsity.com Delayed Sleep-Phase Insomnia Sleep soundly for 8 or more hours but have trouble getting to sleep in the first place. Wake with difficulty and feel sleepy if forced to conform to a normal schedule. Goal is to resynchronize internal clock with other people’s schedules. Docsity.com Seasonal Depression Desynchronization between circadian rhythms, sleep and emotion states may result in depression. Depression is almost invariably cyclic. Many depressed people enter REM sleep earlier than normal. Sleep deprivation may ease depression temporarily. Docsity.com