Chapter 10

Cards (152)

  • regular fluctuations in any living process

    biological rhythms
  • a pattern of behavioral, biochemical, or physiological fluctuation that has a 24-hour period

    circadian rhythm
  • Some biological rhythms are shorter than a day, referred to as ultradian because they repeat more than once per day, usually several minutes to several hours long.
  • Ultradian rhythms are seen in such behaviors as bouts of activity, feeding, and hormone release.
  • rhythmic biological event with a period longer than a day (repeat less than once per day)

    infrdian
  • A familiar infradian rhythm is the 28-day menstrual cycle.
  • Experiments have shown that the duration of light each day is the real trigger for breeding season rather than changes in temperature or food availability. In the laboratory, animals exposed to short days and long nights reliably change to the nonbreeding condition.
  • referring to a rhythm of behavior shown by an animal deprived of external cues about time of day

    free-running
  • The free-running period, the time between two similar points of successive cycles (such as sunset to sunset), differs from one hamster to another, which further explains that they are not detecting some mysterious external cue.
  • Every animal has its own endogenous clock; periods vary from one individual to another.
  • a shift in the activity of a biological rhythm , typically provided by a synchronizing environment stimulus, such as light

    phase shift
  • the process of synchronizing a biological rhythm to an environmental stimulus

    entrainment
  • Any cue that an animal uses to synchronize its activity with the environment is called a zeitgeber.
  • The endogenous clock must receive information about light and dark because light stimuli can entrain circadian rhythms.
  • a small region of the hypothalamus above the optic chiasm that is the location of a circadian clock
    suprachiasmatic nucleus (SCN)
  • What kind of biological rhythm is the sleep-wake cycle?
    circadian
  • Humans need about one day per time zone to entrain after long travel, and in the meantime we experience jet lag, with symptoms such as insomnia and daytime fatigue.
  • What structure in the brain has the function of keeping us awake?
    reticular formation
  • controls the sequence of sleep stages
    hypothalamus
  • Which case study of memory disorders listed below helped us understand the neural pathway in which the hippocampus and temporal cortex play a necessary role in forming new declarative memories?
    NA (still living)
  • The major value of circadian rhythms is that they enable us to anticipate an event, such as sunrise or sunset, and to begin physiological and behavioral preparations before that event.
  • What neurochemical synapse seems to play a role in long-term memory?

    Glutamatergic synapse
  • Early research showed that while removing various endocrine glands had little effect on the free-running rhythms of rats, large lesions of the hypothalamus interfered with circadian rhythms.
  • Lesions in the suprachiasmatic nucleus eliminate circadian rhythms of drinking and locomotor behavior and of hormone secretion.
  • Evidence that supports the idea that SCN contains an endogenous clock is that if you took SCN cells out of the brain and put them into a dish, their electrical activity continues to show a circadian rhythm for days or weeks.
  • What type of attention is associated with an observable orientating response Eg.g a change in ocular gaze.
    Overt attention
  • What area of the brain seems to be part of both reflexive and voluntary attention?
    Parietal lobe
  • The orbital frontal cortex is in which bigger structure below?
    Prefrontal cortex
  • What glutamate hypothesis argues that a deficit in glutamate neurons connecting the prefrontal cortex with the limbic system is the etiology of what mental disorder?
    Schizophrenia
  • What neurotransmitter system do typical antipsychotics work on?
    Dopamine
  • Ralph and Menaker (1988)

    Researched transplants of the SCN into hamsters to show that the SCN is the master clock and proved that the SCN produces a circadian rhythm
  • At night, the pineal gland secretes a hormone, melatonin, that informs the brain about day length.
  • In amphibians and some birds, the pineal glands are sensitive to light and this helps entrain circadian rhythms to light.
  • In mammals, cells in the eye tell the SCN when it is light out and certain retinal ganglion cells send their axons along the retinohypothalamic pathway, veering out of the optic chiasm to synapse directly within the SCN.
  • Most of the retinal ganglion cells that extend their axons to the SCN do not rely on the traditional photoreceptors—rods and cones—to learn about light. Rather, these retinal ganglion cells themselves contain a special photopigment, called melanopsin, that makes them sensitive to light.
  • Taking melatonin at bedtime, thus mimicking the normal nightly release of the hormone from the pineal gland, helps sighted people to get to sleep, and it also helps blind people to entrain to daylight. 
  • While humans rely primarily on light stimulation of the retinohypothalamic tract to the SCN in order to entrain to light, our brains have retained enough sensitivity to melatonin that we can use that cue in the absence of information about light.
  • Deprived of light cues, people free-run just like hamsters. Spending weeks in a cave with all cues to external time removed, they display a circadian rhythm of the sleep-waking cycle that slowly shifts from 24 to 25 hours just as a hamster does.
  • Even though everyone’s clocks/watches/phones report the same time, people in the western part of the time zone go to bed a bit later than those in the eastern part, presumably because the sun sets later in the western half.
  • Neurons in the mammalian SCN
    Make the proteins Clock and Cycle