CSUF PSYC306L FINAL

Circannual rhythms

occur about once every year.

Circadian rhythms

occur about every 24 hours

Ultradian rhythms

occur multiple times within a 24-hour period.

Infradian rhythms

What are some specific examples of daily cycles in humans?occur longer than 24 hours but less than one year.

What are some specific examples of daily cycles in humans?

Sleep-wake cycle, body temperature fluctuations, hormone release

How long is the human circadian cycle?

24.2 hours.

What are free-running conditions? How does it affect circadian clock?

Free-running conditions occur when external time cues (light, clocks, schedules) are removed. Under these conditions, circadian rhythms drift later each day because the internal clock is slightly longer than 24 hours.

What is a Zeitgeber?

A Zeitgeber is an environmental cue that resets or synchronizes biological rhythms.

What is an example of a Zeitgeber?

Light or food timing

What is jetlag?

when internal circadian rhythms become misaligned with local environmental time after traveling across time zones.

How does jet lag affect performance?

Fatigue, Impaired attention, Slower reaction time

What is Seasonal Affective Disorder (SAD)? What causes it?

SAD is a form of depression associated with seasonal decreases in sunlight exposure. Caused by reduced sunlight and increased melatonin

What is the SCN?

Suprachiasmatic Nucleus (SCN) is the master circadian clock located in the hypothalamus. Influenced from light into retina, regulates sleep/ wake and hormones.

What happens when SCN is damaged?

Loss of organized circadian rhythms, Irregular sleep patterns, Hormonal disruption

Describe the retinohypothalamic tract.

The retinohypothalamic tract (RHT) is the neural pathway connecting the retina to the suprachiasmatic nucleus (SCN),

How does retinohypothalamic tract communicate with SCN?

• Light activates intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina.These cells contain melanopsin and are sensitive to blue light.

• Their axons form the RHT and project directly to the SCN in the hypothalamus.

• The ipRGCs release glutamate and PACAP onto SCN neurons. This resets circadian rhythms by altering clock gene activity in the SCN.

What are the masking effects of light? Give 2 specific examples.

Masking effects are direct effects of light on behavior independent of circadian rhythms.

Examples:

• Bright light increases alertness

• Light suppresses melatonin secretion

What were the IV, DV, and results of the Zebrafish Circadian Experiment?

IV:

• Light exposure/light-dark cycle

DV:

• Zebrafish activity or sleep behavior

Results:

• Zebrafish activity synchronized with light-dark cycles.

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What are the two types of skin?

• Glabrous skin: hairless skin (hands/feet); high receptor density

• Hairy skin: lower receptor density

How do receptor numbers vary in skin types?

• Glabrous skin (hairless skin like fingertips, lips, palms) has a high density of sensory receptors, resulting in:

  • Better touch sensitivity

  • Smaller receptive fields

  • Better two-point discrimination

• Hairy skin has a lower receptor density, resulting in:

  • Less precise touch perception

  • Larger receptive fields

What is the order of spinal cord segments?

1. Cervical

2. Thoracic

3. Lumbar

4. Sacral

5. Coccygeal

What are the different types of nociception receptors?

• Mechanical nociceptors

• Thermal nociceptors

• Chemical nociceptors

• Polymodal nociceptors

What are the different types of hapsis?

• Merkel discs

• Meissner corpuscles

• Pacinian corpuscles

What are the different types of proprioception receptors?

• Muscle spindles

• Golgi tendon organs

• Joint receptors

What are receptive fields? What determines them?

A receptive field is the area of the body where stimulation activates a sensory neuron. smaller = better

Determined by:

• Receptor density

• Amount of neural convergence

• Number of sensory receptors

Describe the haptic and proprioceptive pathways.

Haptic/proprioceptive pathway

1. Signal enters spinal cord.

2. Travels ipsilaterally in dorsal columns.

3. Crosses in medulla.

4. Travels contralaterally to thalamus and somatosensory cortex.

Describe the Nociceptive pathway

1. Signal enters spinal cord.

2. Crosses immediately.

3. Travels contralaterally in spinothalamic tract.

4. Reaches thalamus and cortex.

What is the difference between monosynaptic and polysynaptic reflexes?

Monosynaptic reflex

• One synapse

• Fast response, Example: patellar reflex

Polysynaptic reflex

• Multiple interneurons

• More complex response, Example: withdrawal reflex

Pain receptors are stimulated by what stimuli?

Pain receptors respond to:

• Tissue damage

• Extreme heat/cold

• Mechanical pressure

• Chemical irritation

What modifies pain?

• Endorphins

• Attention/distraction

• Emotions

What area of the midbrain regulates pain?

Periaqueductal Gray (PAG)

What neurochemicals block ascending pain signals?

Neurochemicals involved:

• Endorphins

• Enkephalins

• Serotonin

9. Describe the flow of sensory information through Brodmann’s Areas.

1. Sensory receptors detect stimuli.

2. Information travels to the thalamus.

3. Signals reach primary somatosensory cortex (Brodmann Areas 3,1,2).

4. Information moves to association cortices for integration.

What is learning? Memory? Engram?

• Learning: neural changes produced by experience

• Memory: storage and retrieval of information

• Engram: physical neural representation of memory

What is the difference between implicit and explicit memory?

Explicit (declarative) memory

• Conscious recall

• Facts and events

• Hippocampus dependent

• Implicit (procedural) memory

  • Unconscious memory

  • Skills and habits

  • Basal ganglia/cerebellum dependent

What is the pursuit-rootar task? What type of memory does it measure?

The pursuit-rotar task measures motor learning by requiring participants to track a moving target.

Measures:

• Procedural/implicit memory.

How are implicit and explicit memory encoded?

Explicit memory

• Top-down conscious processing

• Requires attention and awareness

Implicit memory

• Bottom-up automatic processing

• Occurs through repeated experience