PSB UNIT2 STUDY GUIDE

What are the main types of cells in the retina?

Receptors (rods and cones), bipolar cells, horizontal cells, amacrine cells, and ganglion cells.

What is the path of light in the retina?

Light first hits receptors, which convert light into electrical signals, sending messages to bipolar cells, which then send messages to ganglion cells.

Which cells send direct messages to bipolar cells?

Receptors (rods and cones) send direct messages to bipolar cells.

Which cells send direct messages to ganglion cells?

Bipolar cells send direct messages to ganglion cells.

What is foveal vision characterized by?

High acuity and color perception due to a dense concentration of cones.

What does peripheral vision primarily detect?

Motion and provides a broader field of view.

What is the ratio of rods to cones in the retina?

20:1.

Which receptors control peripheral vision?

Rods control peripheral vision.

Which receptors control foveal vision?

Cones control foveal vision.

What are the characteristics of rods?

Highly sensitive to light, enable vision in low-light conditions, and do not detect color.

What are the characteristics of cones?

Require brighter light for activation, responsible for color vision, and are concentrated in the fovea.

What does the Trichromatic Theory explain?

Humans have three different types of cones, each sensitive to a different set of wavelengths.

What does the Opponent-Process Theory explain?

We perceive color in terms of paired opposites such as white-black, red-green, and yellow-blue.

What does the Retinex Theory explain?

The cortex compares inputs from different retinal areas to determine brightness and color perception.

Which theory explains negative color afterimages?

The Opponent-Process Theory.

What is color constancy?

The ability to perceive colors of objects despite changes in lighting.

Which theory explains color constancy?

The Retinex Theory.

What is Protanopia?

A type of red-green color blindness due to the absence of red photopigment.

What is Deuteranopia?

A form of red-green color blindness characterized by the absence of green photopigment.

What is Tritanopia?

A rare blue-yellow color blindness resulting from the absence of blue photopigment.

What is Achromatopsia?

A complete absence of color vision, resulting in seeing everything in shades of gray.

Which cells send visual information to the lateral geniculate nucleus?

Retinal ganglion cells send visual information to the LGN.

Which structure receives visual information from the lateral geniculate nucleus?

The primary visual cortex (V1) receives visual information from the LGN.

What is lateral inhibition?

A mechanism where activation of one neuron inhibits neighboring neurons, enhancing contrast.

What is a receptive field?

The portion of the visual field that excites or inhibits a specific neuron.

What are simple receptive fields?

Receptive fields that respond to light stimuli in specific orientations and positions.

What are complex receptive fields?

Receptive fields that respond to stimuli regardless of their exact position.

What is the path of visual information in the visual cortex?

Input → Primary visual cortex → Secondary visual cortex → Visual association areas.

What is the dorsal stream?

The visual path in the parietal cortex.

What is the ventral stream?

The visual path in the temporal cortex.

What impairments result from damage to the dorsal stream?

Understanding what things are but not where they are.

What impairments result from damage to the ventral stream?

Understanding where things are but not what they are.

What is blindsight?

A condition where individuals have visual perception without conscious awareness.

What is visual agnosia?

A disorder characterized by the inability to recognize visually presented objects.

What is prosopagnosia?

The impaired ability to recognize faces without an overall loss of vision.

Which brain areas are involved in face recognition?

Occipital face area, amygdala, and parts of the temporal cortex.

What brain area is responsible for color perception?

The V4 area.

What brain areas are important for motion detection?

Area MT (middle-temporal cortex) and MST (medial superior temporal cortex).

What is amplitude in relation to sound?

The intensity of a sound wave, with greater amplitude sounding louder.

What is sound frequency?

The number of compressions per second, measured in hertz (Hz).

What is pitch in relation to sound frequency?

The perception of frequency, where higher frequency equals higher pitch.

What is timbre?

Tone quality or tone complexity of a sound.

What structures comprise the outer ear?

Pinna and auditory canal.

How does the tympanic membrane respond to low and high frequency sounds?

It vibrates in response to both types of sounds, helping to differentiate them.

What structures comprise the middle ear?

Tympanic membrane, hammer, anvil, and stirrup.

Where are auditory receptors located?

Hair cells within the organ of Corti in the cochlea.

What is the place theory of pitch perception?

Different areas along the basilar membrane vibrate at specific frequencies.

What is the frequency theory of pitch perception?

Certain pitches are perceived when the basilar membrane vibrates in synchrony with sound.

What is amusia?

A disorder where individuals are impaired at detecting small changes in frequency.

What is absolute pitch?

The ability to hear a note and identify it accurately.

Which lobe of the brain processes auditory information?

The temporal lobe.

What kind of stimuli does the primary auditory cortex respond to?

Frequency and amplitude changes.

What is a tonotopic map?

Arrangement of neurons in A1 corresponding to different frequencies.

What is middle ear deafness?

Failure of the middle ear bones to transmit sound waves to the cochlea.

What is inner ear deafness?

Damage to the cochlea, hair cells, or auditory nerve causing hearing impairment.

What are Inter-aural Time Differences (ITD)?

The slight difference in time it takes for a sound to reach each ear, aiding localization.

What are Inter-aural Level Differences (ILD)?

Differences in sound intensity that reach each ear, allowing sound direction determination.

What are Inter-aural Phase Differences (IPD)?

Phase differences in sound waves reaching each ear, helping to localize sound sources.

What cue is useful for localizing high-frequency sounds?

Inter-aural Level Differences (ILD).

What cue is useful for localizing low-frequency sounds?

Inter-aural Phase Differences (IPD).

What is circadian rhythm?

The internal process regulating the sleep-wake cycle and other behaviors in roughly 24-hour cycles.

What activities are controlled by the circadian rhythm?

Sleep, feeding, hormone production, cell regeneration, and other bodily functions.

What happens to circadian rhythm without time cues?

It may drift, causing desynchronization of biological processes.

What is a zeitgeber?

An external cue that helps reset the circadian rhythm.

What role do zeitgebers play?

They synchronize biological processes with the external environment.

How does travel direction affect adjustment to a new time zone?

Westward travel (phase-delay) makes adjustment easier than eastward travel (phase-advance).

How can someone adjust to jet lag?

By gradually adjusting sleep schedules and exposing themselves to light at the appropriate times.

What is the Suprachiasmatic Nucleus (SCN)?

A nucleus located above the optic chiasm in the hypothalamus that controls circadian rhythms.

What pathway connects the retina with the SCN?

The retinohypothalamic pathway.

What type of retinal ganglion cells influence the circadian rhythm?

Retinal ganglion cells that are sensitive to light, particularly blue wavelengths.

How do PER and TIM proteins affect the circadian rhythm?

They fluctuate in concentration, influencing sleepiness and alertness.

What does melatonin do regarding circadian rhythm?

It increases sleepiness and regulates the sleep-wake cycle.

What does a polysomnography measure?

It shows a combination of EEG and eye movement records during sleep.

What does an electroencephalograph measure?

It measures electrical activity in the brain during different sleep stages.

What characterizes stage 1 of sleep?

Light sleep where the person can be easily awakened.

What characterizes stage 2 of sleep?

Deeper sleep with sleep spindles and K-complexes.

What characterizes stage 3 of sleep?

Deep sleep marked by delta waves, crucial for restorative processes.

What is REM sleep characterized by?

Rapid eye movements, increased brain activity, and vivid dreaming.

What is paradoxical about REM sleep?

It is deep sleep in some ways but light in others.

How do REM stages change throughout the night?

REM stages grow longer toward the morning while stages 3 and 4 become shorter.

What are the differences between REM and NREM dreams?

REM dreams tend to be vivid and narrative-driven, while NREM dreams are often fragmented.

What structures influence arousal and attention?

Locus coeruleus, reticular formation, and basal forebrain.

What neurotransmitter is released by the locus coeruleus?

Norepinephrine.

What neurotransmitter is released by the basal forebrain?

GABA and acetylcholine.

What role does GABA play in sleep?

It promotes relaxation and reduces neuronal excitability for stable sleep.

Does brain activity increase during REM sleep?

Yes, in the pons, limbic system, and parietal and temporal cortex.

What decreases in activity during REM sleep?

Activity decreases in the primary visual cortex, the motor cortex, and dorsolateral prefrontal cortex.

What is sleep apnea characterized by?

Repeated interruptions in breathing during sleep.

What characterizes narcolepsy?

Uncontrollable episodes of sleep during the day.

What is REM Behavior Disorder?

Individuals act out their dreams during REM sleep.

What is sleepwalking?

Getting up and walking around while in a state of sleep, typically during non-REM sleep.

What are the main symptoms of narcolepsy?

Excessive daytime sleepiness, cataplexy, sleep paralysis, and hypnagogic hallucinations.