Rhythms and Sleep: Timekeeping Mechanisms of the Brain

Question 1

period

Answer 1

time it takes to go through a cycle

Question 2

phase shift

Answer 2

resetting the clock by an external cue

Question 3

entrainment

Answer 3

process of phase shifting

Question 4

zeitgeber

Answer 4

time giver, primary one is the sun

Question 5

ecological significance

Answer 5

anticipation of events in environment

Question 6

possible sites for brain clock

Answer 6

pineal gland, retinal cells, raphe nuclei, adrenal cortex etc. researchers ended up focusing on the suprachiasmatic nucleus

Question 7

retinohypothalamic tract

Answer 7

where some amphibians and birds have a third eye, aka their pineal gland is sensitive to light, regulates rhythm

Question 8

molecular foundations of the clock

Answer 8

regulation of gene transcription via negative feedback loops in SCN produces rhythms

Question 9

shorter rhythms

Answer 9

ultradian rhythms - occur more than once per day, periods last from several minutes to hours

Question 10

longer rhythms

Answer 10

infradian rhythms - less than once per day

Question 11

circannual rhythms

Answer 11

seasonal cycles - about a year, good for winter survival and coordinated reproduction. two major types of seasonal rhythms: endogenous/exogenous control and true endogenous control

Question 12

type i: endogenous/exogenous control

Answer 12

due to photoperiodism, lesions to the SCN prevents these cycles

Question 13

type ii: true endogenous control

Answer 13

SCN lesions do not affect these cycles, indication that there mucuh be secondary pacemakers