Psychology 224: Neuroscience Lecture (PDF)

Psychology 224: Neuroscience Sensory Systems: Audition; Sleep and Biological Rhythms Reading: Carlson, Chapters 7 &9  Announcement Exam #3 Exam 3 will be on 11/7, not 11/4. The Auditory System Anatomy of the Ear 3....

Psychology 224: Neuroscience Sensory Systems: Audition; Sleep and Biological Rhythms Reading: Carlson, Chapters 7 &9  Announcement Exam #3 Exam 3 will be on 11/7, not 11/4. The Auditory System Anatomy of the Ear 3. 4. 1. 2. The Organ of Corti Central Auditory Pathways 4. The cortex is last 3. The inferior colliculus is the next synapse, followed by the medial geniculate 1. nucleus 2. The auditory nerve synapses Most cochlear in the cochlear axons cross nucleus over & synapse in the  Auditory Cortical Areas The primary auditory cortex is adjacent to the upper bank of the lateral fissure in the temporal lobe – Each hemisphere receives information from both ears, but primarily the contralateral one The auditory association cortex surrounds the primary auditory area Like the visual system, there are 2 streams of auditory information flow: – 1) the dorsal stream – terminates in the posterior parietal region and is involved in sound localization (the “where”) – 2) the ventral – terminates in the temporal lobe and is involved in processing of complex sounds (the “what”) What is Sleep?  The Study of Sleep In the lab, sleep is studied by measuring the activity of the brain and of 2 different muscle groups: – 1) Electroencephalogram (EEG) – attach electrodes to the scalp to record the collective activity of thousands of brain cells (typically on the cortical surface) – 2) Electromyogram (EMG) – attach electrodes to the chin to monitor muscle activity – 3) Electrooculogram (EOG) – attach electrodes around the eyes to monitor eye movements  2 patterns of activity Alpha activity: state of relaxation 8-12 Hz 13-30 Hz Beta activity: state of arousal (desynchronized) 3.5-7.5 Hz Transitional ** The EEG 12-14 Hz becomes more synchronized as 20-50% Delta sleep progresses from stages 1-4, < 3.5 Hz and the waves become slower > 50% Delta (low frequency, **REM looks like synchronized) the awake state  Non-REM Sleep Stages 1-4 of sleep are called typically called “non-REM sleep” Stages 1-2 are transitional; the subject typically is not aware s/he is asleep Stages 3-4 are known as slow wave sleep, mostly because the presence of low-frequency delta activity Slow-wave sleep is characterized by: – Light, even respiration – Presence of muscle tone – Difficulty in arousing subject  REM Sleep Occurs ~ every 90 mins throughout the night Characterized by: – Enhanced respiration and blood pressure – Rapid eye movements (REMs) – Complete loss of muscle tone (paralysis) – Vivid, emotional dreams  Cycles of Sleep We alternate between periods of REM and non-REM sleep. Each cycle of sleep is ~90min long. Each cycle of sleep contains ~ 20-30 minutes of REM sleep. In one night (8 hours), there will be 4-5 periods of REM sleep.  Time Mostly slow-wave sleep Mostly REM sleep and stage 2 Disorders of Sleep  Insomnia Difficulty falling asleep after going to bed or after awakening during the night. One study found no difference in time spent sleeping between people who said they had insomnia and those who did not. There were personality differences (Rosa and Bonnet, 2000). People with sleep apnea fall asleep and the stop breathing, usually caused by obstruction in the airway. This is one form of insomnia.  Narcolepsy Characterized by sleep (or some of its components) at inappropriate times. Primary symptom: Sleep attack lasts usually 2-5 minutes. – Intense urge to sleep that can happen any time, but usually under monotonous, boring conditions. – Person usually wakes up feeling refreshed.  Narcolepsy Another symptom is cataplexy: muscle weakness, even muscular paralysis (like that during REM sleep) at an inappropriate time. – Person lies down for seconds to minutes fully conscious. – Brought on by strong emotional reactions or physical effort.