Chapter2 Flashcards
What do sense organs do?
Transform stimuli into perceptions
What is the process by which stimuli are converted to electrical signals?
Transduction
What do we perceive through our sense organs?
Energy and molecules
What percentage of the cerebral cortex is involved in the visual system?
30 percent
What is the primary function of vision?
Perceiving surroundings
How does the brain process visual messages?
Through specialized areas
What has been studied intensively related to sensory systems?
Vision
Which organisms have primarily contributed to knowledge of light energy conversion?
Fruit flies and mice
In what animals has higher-level visual processing been studied?
Monkeys and cats
How can seeing with your eyes be compared?
Like taking pictures
What regulates light entry into the eye?
Iris
What structure allows light to enter the eye?
Pupil
What structure focuses light onto the retina?
Lens
What does the cornea do?
Initial focusing
What is the surface where light is focused called?
Retina
How does the lens adjust focus?
Thickens or flattens
How is visual input mapped on the retina?
Two-dimensional reversed image
Where do objects to the right project images?
Left side of retina
Where are photoreceptors located in the retina?
Peripheral layer
What do ganglion cells and interneurons do?
Process and relay information
What forms the optic nerve?
Axons of ganglion cells
What is the purpose of photoreceptors?
Convert light to signals
What is the process of converting energy known as?
Transduction
What percentage of photoreceptors are rods in humans?
95 percent
What do rods allow you to see in?
Dim light
What do cones detect?
Detail and color
What types of cones are in the human eye?
Red, green, blue
How do cones convey color information?
Differing combinations
Where is vision sharper in the retina?
Center of retina
What is the fovea?
Small area with dense cones
What types of cones are in the fovea?
Red and green cones
What is the function of the macula?
Critical for reading and driving
What is macular degeneration?
Death of photoreceptors in macula
What is a leading cause of blindness in those over 55?
Macular degeneration
What is the input pattern for ganglion cells in the macular region?
Few cones
What allows for high visual acuity in the macular region?
Fine details resolution
How do inputs to ganglion cells differ near the margins of the retina?
Many photoreceptors
What is less detailed in vision?
Peripheral vision
What is the area providing input to a single ganglion cell?
Receptive field
What do axons extend through to reach the brain?
Optic nerve
What type of cells provide nutritional support to the retina?
Astrocytes
What begins visual processing?
Comparing light amounts
What do the receptive fields of ganglion cells provide?
Complete 2D representation
What activates a ganglion cell’s receptive field?
Light hits center region
What inhibits a ganglion cell’s receptive field?
Light hits surrounding area
What happens when light strikes the entire receptive field?
Weak response
What is the first way the visual system maximizes perception of contrast?
Center-surround antagonism
How is neural activity from ganglion cells transmitted?
Via optic nerves
What results from the exit point of the optic nerve?
Blind spot
How does the brain deal with the blind spot?
Fills in information
What is the optic chiasm?
Crossover junction
Where do the signals from the left side of the retinas go?
Left side of the brain
Where do the signals from the right side of the retinas go?
Right side of the brain
Cells in the primary visual cortex are arranged in layers.
True
Cells in the middle layer of the primary visual cortex have receptive fields similar to those in the retina.
True
Cells above and below the middle layer of the primary visual cortex have more complex receptive fields.
True
Some cells in the primary visual cortex can respond to edges at a certain angle.
True
Some cells in the primary visual cortex can respond to moving stimuli.
True
New processing streams pass information from the primary visual cortex to other parts of the visual cortex.
True
What happens to receptive fields as visual information is combined?
Becomes complex and selective
What types of stimuli do some neurons at higher processing levels respond to?
Specific objects and faces
What are the two main visual processing streams?
Dorsal and ventral
Which lobe does the dorsal stream go toward?
Parietal lobe
Which lobe does the ventral stream go toward?
Temporal lobe
What does the ventral stream process?
Shape and color recognition
What does the dorsal stream process?
Spatial relationships and motion
What is the purpose of the dorsal stream?
Create action plan
What does ongoing research suggest about the division of labor in the brain?
Crosstalk may create experience.
What is binocular vision?
Seeing with two eyes.
What does binocular vision allow you to perceive?
Depth or three dimensions.
What condition causes reduced depth perception?
Strabismus
Where is information from both eyes processed?
Primary visual cortex
What is the benefit of having two eyes?
Larger visual field
What happens at the optic chiasm?
Nerve fibers cross over
Which side of the brain processes signals from the left visual field?
Right side
Which half of the cerebrum processes information from the opposite body side?
Each half
What have animal studies provided insights into?
Treating visual disorders
What animal research has aided strabismus therapies?
Cats and monkeys
What happens to children with strabismus?
Favor one eye
When does blindness from strabismus become permanent?
Age 8
What was the previous age for surgery on children with strabismus?
Age 4
When is strabismus best corrected?
Before age 4
What lies at the heart of disorders causing blindness?
Photoreceptor loss
What can gene or stem cell therapies help recover?
Photoreceptors
What have gene therapies enabled for patients with macular degeneration?
See better
What new approach is being explored for genetic blindness?
Send signals to brain
How is the new approach for blindness similar to deafness treatment?
Cochlear implants
What is the importance of hearing?
Alerts to danger, aids communication
What qualities does the auditory system detect?
Pitch, loudness, duration, location
How does hearing impact social interactions?
Facilitates communication
What does the auditory system analyze?
Complex sounds
What can you follow in a conversation or music?
Particular voices or instruments
What is required for hearing?
Conversion of sound waves
How are sound waves carried to the brain?
Electrical signals by nerve cells
How does sound reach the eardrum?
Air pressure waves funnel into ear canals
What are the three tiny bones in the middle ear?
Malleus, Incus, Stapes
What does the stapes do?
Acts like a tiny piston
What separates the middle ear from the cochlea?
Oval window
What does the oval window convert?
Mechanical vibrations
What are the pressure waves transduced into?
Electrical signals
What runs along the inside of the cochlea?
Basilar membrane
How do different frequencies affect the cochlea?
Higher pitches near oval window, lower in center
What happens when the basilar membrane moves?
Hair cells bend against tectorial membrane
What opens channels in stereocilia?
Bending
What do hair cells excite?
Auditory nerve
What is the brain’s relay station for sensory information?
Thalamus
Where does sound processing go after the thalamus?
Cerebral cortex
What are hair cells responsive to?
Narrow range of sound frequencies
Where are hair cells located?
Along the basilar membrane
What do nerve fibers connected to hair cells carry?
Information on specific frequencies
How is sound direction computed?
Brainstem and thalamus
What maintains the frequency map?
Basilar membrane
Where do different auditory neurons respond to frequencies?
Primary auditory cortex
What do some cortical neurons respond to?
Intensity, duration, frequency change
What do other neurons specialize in?
Complex sounds, combinations of tones
What do smell and taste perceive?
Tiny molecules
Why are smell and taste important to survival?
Detect hazardous substances
What can harm taste and smell cells?
Outside environment
What kind of cells regularly regenerate?
Taste receptor cells
Which sensory neurons are continually replaced?
Olfactory neurons
How do we taste food?
Detected molecules
Where are taste buds located?
Tongue and mouth
How many taste buds do we have?
5,000 to 10,000
At what age do we start losing taste buds?
Around age 50
How many sensory cells does each taste bud consist of?
50 to 100
What are the five basic taste qualities?
Sweet, sour, salty, bitter, umami
What cranial nerves are involved in taste?
Facial, glossopharyngeal, vagus
Where do taste impulses route through?
Thalamus to gustatory cortex
What part of the brain identifies taste perceptions?
Frontal lobe and insula
How do odors enter the nose?
Air currents
What do odors bind to in the nasal cavity?
Olfactory cells
What enters the olfactory bulbs?
Sensory neuron axons
Where does smell information go first?
Olfactory cortex
What is unique about the smell sensory system?
Bypasses thalamus
How many types of olfactory cells do we have?
Around 1,000
How many smells can we identify?
About 20 times more
What do olfactory cells have that helps them detect odors?
Hair-like cilia
What creates a distinct activity pattern in the olfactory system?
Unique smell stimulation
Where is the primary olfactory cortex located?
Temporal lobe
How quickly can people identify odors?
110 milliseconds
What can change over time in relation to the olfactory bulbs?
Size and neuron organization
What is unique about the olfactory bulbs in rodents and primates?
Neurogenesis throughout life
What happens to taste when the nose is stuffed up?
Food tastes bland
How does smell influence taste perception?
Enhances flavor complexity
What enhances taste perceptions?
Matching tastes and smells
How does sugar taste with strawberry smell?
Sweeter
Where do taste and smell information converge?
Central regions of the brain
What do taste buds do?
Transform taste information
What connects taste receptors to the brain?
Axons
What do hair cells in the cochlea convert?
Vibrations to electrical signals
How are signals sent to the brain?
Via cochlear nerve
What happens to taste and smell sensitivity as we age?
Sensitivity decreases
What causes the loss of taste and smell sensitivity?
Damaged receptors
What is current research focused on regarding taste and smell?
Stem cells and neurons
What potential future application is mentioned for stem cell research?
Restore taste or smell
What system is responsible for touch sensations?
Somatosensory system
What types of sensations does the somatosensory system include?
Touch, pressure, pain, etc.
Where are the nerve endings for touch receptors located?
Different skin layers
What type of skin has sensitive nerve endings around hair bases?
Hairy skin
How do touch signals travel?
Sensory fibers to spinal cord
Where are touch signals translated?
Somatosensory cortex
What are A-beta fibers?
Thick myelinated axons
What are C fibers?
Thin unmyelinated axons
What forms a topographic map on the cortex?
Somatosensory information
Which body areas are most sensitive to touch?
Lips and fingertips
What affects sensitivity to touch and pain?
Receptors per unit area
Why is the back less sensitive than the hands?
Few, far apart receptors
What is two-point discrimination?
Identifies distinct stimuli.
Where is acuity greatest?
Densely nerve-packed areas.
What is the two-point threshold?
Lowest in densely nerve-packed areas.
What are nociceptors?
Special sensory fibers
What does pain signal?
Tissue damage
What are the components of pain?
Sensory and emotional
What is the primary function of pain?
Warning signal
What do nociceptors normally respond to?
High-threshold stimuli
What types of painful stimuli are nociceptors sensitive to?
Thermal, mechanical, chemical
What can trigger a burning pain in nociceptors?
Capsaicin in spicy food
What stimulates itch-specific nociceptors?
Chemical stimuli
What activates histamine receptors?
Skin irritation
What is released at the site of tissue injury?
Various chemicals
What does tissue injury cause?
Inflammation
What do prostaglandins do?
Enhance pain sensitivity
What condition can peaks of pain sensitivity lead to?
Allodynia
What can a long-lasting injury cause?
Nervous system changes
What is neuropathic pain?
Hypersensitivity to pain
What causes diabetic neuropathy?
High blood sugar
What symptoms are associated with diabetic neuropathy?
Numbness, tingling, burning, aching
What fibers transmit pain and itch messages?
A-delta and C fibers
What do A-delta fibers evoke?
Sharp pain
How do C fibers transmit pain?
More slowly
What kind of pain do C fibers produce?
Dull and diffuse
Where do pain and itch signals travel to?
Thalamus
What happens to pain and itch messages in the brain?
Transformed into conscious experience
What factors affect pain experience?
Strength of stimulus, emotional state, setting
What does the cortex do when pain messages arrive?
Processes them in different ways
Which region does the cortex send pain messages to?
Periaqueductal gray matter
What does the periaqueductal gray matter activate?
Descending pathways that modulate pain
What substances do the pathways release?
Endorphins
What do endorphins act like?
Analgesic morphine
What is adrenaline’s role in stressful situations?
Analgesic effect
How does the body regulate pain?
Intercepts pain signals
What influences how much pain a person feels?
Efficacy and sensitivity of brain circuits
Why do some people develop chronic pain?
Does not respond to treatment
What do endorphins act on in the brain and spinal cord?
Opioid receptors
What is the implication of opioid drugs for surgery?
Pain reduction
What are scientists studying to relieve pain?
Electrical stimulation of spinal cord
What influences pain perception?
Emotional and sensory components
Which methods target the emotional component of pain?
Meditation, hypnosis, etc.
Is there a single brain area for pain perception?
No single area responsible
How does cannabis affect pain perception in the brain?
Suppresses activity in pain areas
Which brain area is primarily affected by cannabis for pain?
Limbic system
What do the sensory nerve fibers in the mouse embryo detect?
Pressure, pain, temperature, itch
