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Questions and Answers
Which auditory landmark is the next synapse after the cochlear nucleus?
What part of the ear is responsible for sound transduction?
In which region does the dorsal stream of auditory information terminate?
How does the primary auditory cortex primarily receive auditory information?
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What is the primary function of the ventral stream in auditory processing?
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Which physiological measurement records the collective activity of thousands of brain cells?
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What characterizes the sleep stages known as slow-wave sleep?
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During REM sleep, which of the following is NOT a characteristic observed?
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How often does REM sleep typically occur during the night?
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Which sleep stage is characterized by difficulty in arousing the subject?
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What is the frequency range of alpha activity during sleep?
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Which of the following features is typical of REM sleep?
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What is the typical duration of a complete cycle of sleep?
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What percentage of V1 is devoted to processing information from the fovea?
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The primary visual cortex is also referred to as the striate cortex.
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What are the two main processing streams that visual information can take after V1?
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Sound is first collected from the environment by the ______.
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What is the tympanic membrane also known as?
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What are the three tiny bones in the middle ear called?
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Which bone connects to the oval window of the cochlea?
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Study Notes
Anatomy of the Ear
- The ear is made up of three main parts: the outer ear, the middle ear, and the inner ear
- The outer ear collects sound waves and channels them through the ear canal to the eardrum
- The middle ear contains the ossicles: the malleus, incus, and stapes
- The ossicles amplify sound vibrations and transmit them to the oval window of the inner ear
- The inner ear contains the cochlea, which is filled with fluid and lined with hair cells
- The organ of Corti contains the hair cells which are responsible for converting sound vibrations into electrical signals that are sent to the brain
Central Auditory Pathways
- The auditory nerve carries signals from the cochlea to the brain
- The first synapse in the brain is located in the cochlear nucleus
- The cochlear nucleus sends signals to the superior olivary nucleus; at this stage, most cochlear axons cross over
- The superior olivary nucleus sends signals to the inferior colliculus
- The inferior colliculus sends signals to the medial geniculate nucleus of the thalamus
- The medial geniculate nucleus sends signals to the auditory cortex
Auditory Cortical Areas
- The primary auditory cortex is located in the temporal lobe, just above the lateral fissure
- Each hemisphere of the brain receives auditory information from both ears, but mainly from the contralateral ear
- The auditory association cortex surrounds the primary auditory cortex
- The auditory system has 2 streams: the dorsal stream and the ventral stream
- The Dorsal stream is involved in sound localization and ends in the posterior parietal region
- The Ventral stream is involved in processing complex sounds and ends in the temporal lobe
What is Sleep?
- Sleep is a state of reduced consciousness and responsiveness to external stimuli
- Sleep is important for many biological processes, including memory consolidation, hormone regulation, and immune function
- Sleep is studied in the lab by measuring brain activity and muscle activity
- Electroencephalogram (EEG) measures the electrical activity of the brain
- Electromyogram (EMG) measures muscle activity
- Electrooculogram (EOG) measures eye movements
The EEG
- The EEG is used to study sleep because the patterns of electrical activity in the brain change throughout the sleep cycle
- The EEG shows different brain wave patterns depending on whether the person is awake, asleep, or dreaming
- While awake, there are two patterns of activity: alpha and beta waves
- Alpha activity occurs in a relaxed state, and beta activity occurs in a state of arousal
- During sleep, the EEG becomes more synchronized and the waves become slower
- The delta wave occurs during deep sleep
- REM sleep looks like the awake state
Non-REM Sleep
- Stages 1-4 of sleep are referred to as non-REM sleep
- Stages 1-2 are considered transitional states; the subject is not fully aware they are asleep
- Stages 3-4 are called slow-wave sleep due to low-frequency delta activity
- Slow-wave sleep is characterized by light respiration, muscle tone, and difficulty arousing the subject.
REM Sleep
- REM sleep occurs roughly every 90 minutes throughout the night
- REM sleep is characterized by rapid eye movements, loss of muscle tone, and vivid dreams
- Other features of REM sleep include enhanced respiration and blood pressure
Cycles of Sleep
- Throughout the night, we cycle between periods of REM and non-REM sleep
- Each cycle of sleep is approximately 90 minutes long
- Each cycle contains about 20-30 minutes of REM sleep.
- In one night (8 hours), there will be about 4-5 periods of REM sleep.
The Visual System
- Retinal ganglion cells encode the amount of light that falls on their receptive fields, and the wavelength of the light.
- The primary visual cortex is also known as the "striate cortex".
- The striate cortex contains a dark staining layer.
- The primary visual cortex is devoted to processing information from the fovea.
- Each cell in the primary visual cortex collects information from multiple retinal ganglion cells.
- Most neurons in V1 are sensitive to orientation.
- V1 cells can only identify features of a visual image and not a whole object.
- The extrastriate cortex (V2) receives input from V1 cells and combines the features received from V1 to reassemble a visual scene.
- The ventral stream is responsible for "what" an object is.
- The dorsal stream is responsible for "where" an object is.
The Auditory System
- Sounds are produced by objects that vibrate.
- A vibrating object causes air molecules to compress and expand, creating a sound wave.
Structure of the Human Ear
- The outer ear collects sound from the environment.
- The pinnae funnel sound into the ear canal.
- The ear canal enhances certain sound frequencies.
- The tympanic membrane is the eardrum.
- The tympanic membrane is a thin membrane that vibrates in response to sound.
- The malleus, incus, and stapes are the ossicles in the middle ear.
- The ossicles amplify and transmit sound to the inner ear.
- Variations in the tympanic membrane first reach the malleus.
- The malleus is connected to the incus.
- The incus connects to the stapes.
- The stapes is the smallest bone in the body.
- The stapes is connected to the oval window of the cochlea.
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Description
Explore the intricate anatomy of the ear, from the outer ear to the inner ear, and understand the central auditory pathways. This quiz covers the structures involved in hearing and how sound signals are transmitted to the brain. Test your knowledge on the parts of the ear and their functions.
