Exam Review Questions Flashcards
What is a biorhythm? Discuss different types of biorhythms.
A variation in a biological process that repeats (or cycles) over a period of time (e.g. 24 hours). Entrained? Constant Routine?
What do we mean when we say a biorhythm is internal?
- Some people don’t require cues from the environment (though they can be modified by them)
- We call such rhythms endogenous or free-running rhythms
- In the study a pattern of leaf movement is observed over time even without much light
Describe how biorhythms may shift when lighting conditions change
- Our sleep-wake cycle is entrained to light cues that tend to come at specific times (e.g. from the sun)
- When light cues are delivered over inappropriate times, our normal sleep-wake cycle is disrupted
- In the absence of external cues, the sleep-wake cycle in humans shifted from 24 hours to 25-27 hours (every day cycle is a little off)
What role does the suprachiasmatic nucleus play in biorhythms?
- The SCN named for its proximity to the optic chiasm
- SCN lesion abolishes many circadian rhythms
- An SCN-lesioned animal can recover rhythms if ti recieves a transplantation of SCN neurons from a healthy animal
- The ‘restored rhythm’ in the lesioned animal matches the rhythm of the implanted SCN neurons
- SCN neurons have a rhythmic activity that is linked to animal’s cycle (e.g. cells are more active during the day in diurnal animals)
- SCN neurons maintain rhythmic activity even when deprived of input (i.e. if their inputs are severed) or removed from the brain entirely
What is delayed sleep phase disorder?
- CRY1 gene was associated w/ delayed sleep phase disorder and ADHD accompanied by insomnia
- Disorder in which a person’s sleep is delayed by two hours or more what is beyond what is considered an acceptable or conventional bedtime
Explain the relationship between arousal, melatonin and cortisol
- Melatonin: physiologic pressure for sleep (the pineal gland is a key site of production - which is inhibited by light)
- Cortisol: The paraventricular nucleus (PVN) is key to the initiation of cortisol (CORT) production (In morning increase in cortisol as a waking response)
- Melatonin levels start rising several hours before sleep whereas cortisol levels rise before waking up
Explain the significance of the reticular formation to arousal/wakefulness.
- Sensitive to sensory input
- Connected to the basal forebrain, providing cholinergic stimulation to the rest of the brain
- Stimulation of the reticular formation promotes arousal
- Coma can occur w/ injury
Why do we need sleep?
- Maintenance of the brain (clearance of waste) and restoration of injured/damaged tissue
- Ontogenetic development of the brain
- Maintenance of learning + memory processes
- Energetically favorable
- Dreaming
What are the stages of sleep? Explain sleep stage cycling.
Stage NREM1 (light sleep): Slightly lower frequency activity - Theta waves
Stage NREM2: Lower frequency activity with sleep - Sleep spindles
Stage NREM3 (Deep Sleep or Slow Wave Sleep): Mostly very low frequency activity - Delta waves - efficient sleepers (>6 hours) spend more time in NREM3
REM (Dream stage): High frequency activity, similar to eyes-open wakefulness - Fast, random
Sleep stage cycling ensures we spend a little time in each stage of sleep, but shows we spend majority of our time in NREM sleep
How does sleep change with age?
Greater sleep latency (time it takes to fall asleep), more arousal periods (likely awakenings), less REM, less NREM3, less overall sleep
Is REM necessary for survival? What happens with REM deprivation?
- With REM deprivation there is REM rebound (enter REM stage sooner, spend longer in REM stage)
- Lack of REM associated w/ reduced hippocampal neurogenesis, immune dysfunction + mood disruption (however, suppression of REM occurs w/ antidepressant drugs, like SSRIs, which improve mood)
- REM might be a preparatory stage for wakefulness (replacing REM stages w/ wakeful states prevents rebound)
Compare the concepts of wakefulness, awareness, attention and consciousness.
- Consciousness: an awareness of the external and/or internal world
- Regions in the thalamus and brain stem are vital to arousal/wakefulness (gating, ‘on switch’) but should not be considered the site of consciousness generation
- Consciousness is not attention, but allows for the voluntary employment deployment of attention
Discuss the history of consciousness research
- Philosophers have been debating the issue for many years, but scientists only got involved recently (lack of suitable techniques/approaches a factor)
- Early perspectives in psychology may have indirectly decreased interest and slowed progress (psychoanalysis was focused on the unconscious, behaviourism focused on the behavioural changes induced by stimuli, without consideration of the mind)
- Progress was slow until the late 1980s/early 1990s, when influential papers (mostly theoretical) began to emerge
- At this time, philosopher David Chalmers argued there were two main problems in the field
- Specialized journals focusing on consciousness appeared in the 1990s
- Consciousness events are held regularly, including an annual gathering in Tuscon
- Experimental studies, often featuring neuroimaging techniques, are becoming more common
What tools/strategies do we use to measure and differentiate states of
consciousness?
- Neural correlates (Brain activity [fMRI/EEG] and metrics based on it [PCI])
- Physiological correlates (heart rate, blood pressure)
- Behavioural correlates (response to stimuli [pain, heat, sounds, objects], for example via the Glasgow coma scale (GCS)
- Self-reported phenomenological correlates (first-person, subjective) [altered state of consciousness scale]
Describe two-dimensional and multi-dimensional models of consciousness.
Two-dimensional: wakefulness and awareness, difference states categorized by where they fall on scale
Multi-dimensional: multiple dimensions or aspects other than wakefulness and awareness - distinct dimensions for attention, self-awareness, and sensory experience
