Proprioception and Auditory Perception PDF

# Proprioception - Sense of place and position - Sensory afferents - Muscle spindles - Joint receptors - Cutaneous afferents - Other mechanisms - Force feedback (Golgi tendon organ) - Effort feedback (Renshaw/recurrent inhibition) # Recap: Case study of deafferented patients -...

# Proprioception - Sense of place and position - Sensory afferents - Muscle spindles - Joint receptors - Cutaneous afferents - Other mechanisms - Force feedback (Golgi tendon organ) - Effort feedback (Renshaw/recurrent inhibition) # Recap: Case study of deafferented patients - Differences between IW and GL - Balance - Mirror drawing tasks - How do multiple senses work together in the control of movement? # Muscle Spindle - Bundles of encapsulated, specialized fibers - Sensory afferents - Muscle spindles send information to the spinal cord via IA fibers # Golgi Tendon Organ - Interwoven collagen and neural fibrils - Series connection between fiber & tendon - Active force sensor - Fibers pulls collagen - Collagen deforms neuron - Whereas Golgi tendon organs send information to the spinal cord via the IB fibers. # Visual Proprioception and Arm Location An image was provided for this section, but it is not able to be displayed here. The image shows a person with their right hand extending from the left edge of the image. The hand is bent at the wrist, and the thumb is oriented towards the ceiling. The person's left forearm is resting on a table that is parallel to the edge of the image. The left forearm is bent at the elbow to a 90 degree angle. The person's left hand is resting flat on the table, with the thumb oriented towards the ceiling in a position similar to the position of the left hand in the image. A rubber hand is shown with it's palm facing the person's left hand, with the fingers oriented in a position similar to the person's left hand in the image. The rubber hand is visible to the person, while the person's right hand is not. The person is positioned so that they are looking at the rubber hand. There are descriptions below the image that explain what each element is and how it is being used. The tool that stimulates the person's hand is a sharp pin and a paintbrush, the tool that stimulates the rubber hand is also a sharp pin and a paintbrush. The image is meant to display how visual information can create a false sense of proprioception. # One more time... - How do visual and proprioceptive systems come together? - Sense of position comes from both. - Sensory systems can combine seamlessly or can be in conflict. # The Auditory System An image was provided for this section. The image shows a cross-section of a human head with the ear highlighted along with the inner workings of the ear. The auditory nerve is shown leading from the inner ear to the brain. The illustration shows how the auditory nerve connects to the brain through a series of nuclei. # Sound - A Longitudinal, mechanical wave - Caused by vibrating source - Pack molecules at different densities - Cause small changes in pressure - Model pressure differences as sine waves # Sound Waves - Pure Tones - simple waves - Harmonics - complex waves consisting of combinations of pure tones (Fourier analysis) - The quality of tone or its timbre (i.e. the difference between a given note on a trumpet and the same note on a violin) is given by the harmonics. # Changes in Air Pressure An image was provided for this section. The image depicts the changes in air pressure caused by a vibrating source. The image shows a series of four rows. Each row depicts a vibrating source pushing against air molecules. The top three rows demonstrate how the air molecules are affected by movement in the vibrating source, and the bottom row shows the pressure differences in the form of sine waves. # Frequency (temporal) Theory - Periodic stimulation of membrane matches frequency of sound. - One electrical impulse at every peak - Maps time differences of pulses to pitch - Firing rate of neurons far below frequencies that a person can hear - Volley theory: Groups of neurons fire in well-coordinated sequence. # Physical Dimensions of Sound - Amplitude - Height of a cycle - Relates to loudness - Wavelength (w) - Distance between peaks - Frequency (λ) - Cycles per second - Relates to pitch - λw = velocity - Most sounds mix many frequencies & amplitudes # Auditory Perception Auditory perception is a branch of psychophysics. Psychophysics studies relationships between perception and physical properties of stimuli. ## Physical dimensions: Aspects of a physical stimulus that can be measured with an instrument (e.g., a light meter, a sound level meter, a spectrum analyzer, a fundamental frequency meter, etc.) ## Perceptual dimensions: These are the _mental experiences_ that occur inside the mind of the observer. These experiences are actively created by the sensory system and brain based on an analysis of the physical properties of the stimulus. Perceptual dimensions can be _measured_, but not with a meter. Measuring perceptual dimensions requires an observer (e.g., a listener). # Visual Psychophysics ## Perceptual Dimensions - Hue - Brightness - Shape ## Physical Properties of Light - Wavelength - Luminance - Contour/Contrast # Auditory Psychophysics ## Perceptual Dimensions - Pitch - Loudness - Timbre (sound quality) ## Physical Properties of Sound - Fundamental Frequency - Intensity - Spectrum Envelope/Amp Env # The Three Main Perceptual Attributes of Sound - Pitch (not fundamental frequency) - Loudness (not intensity) - Timbre (not spectrum envelope or amplitude envelope) The terms _pitch_, _loudness_, and _timbre_ refer not to the physical characteristics of sound, but to the mental experiences that occur in the minds of listeners. # Recap - Somatosensory system: Touch, position, force - Auditory system, properties of sound. - Difference between physical properties and perception (_pitch_, _loudness_, and _timbre_ refer mental/neural experiences). - The ear is more sensitive to Fo differences in the low frequencies than the higher frequencies. - Loudness is strongly affected by the frequency of the signal. If intensity is held constant, a _mid-frequency signal_ (in the range from ~1000-4000 Hz) will be louder than lower or higher frequency signals. # Perceptual Dimensions - Pitch - Higher frequencies perceived as higher pitch - Humans hear sounds in 20 Hz to 20,000 Hz range - Loudness - Higher amplitude results in louder sounds - Measured in decibels (db), 0 db represents hearing threshold # Perceptual Dimensions (cont.) - Timbre - Complex patterns added to the lowest, or fundamental, frequency of a sound, referred to as spectrum envelope - Spectrum envelopes enable us to distinguish musical instruments - Multiples of fundamental frequency give music. - Multiples of unrelated frequencies give noise # Decibels of Everyday Sounds | Sound | Decibels | |:---|:---| | Rustling leaves | 10 | | Whisper | 30 | | Ambient office noise | 45 | | Conversation | 60 | | Auto traffic | 80 | | Concert | 120 | | Jet motor | 140 | | Spacecraft launch | 180 | # Pitch and Fundamental Frequency All else being equal, the higher _the Fo_, the higher the perceived pitch. # Pitch Perception The ear is more sensitive to _Fo_ differences in the low frequencies than the higher frequencies. This means that: 300 vs. 350 ≠ 3000 vs. 3050 That is, the difference in perceived pitch (not _Fo_) between 300 and 350 Hz, is _NOT_ the same as the difference in pitch between 3000 and 3050 Hz, even though the physical differences in _Fo_ are the same. # Loudness and Intensity All else being equal, the higher the intensity, the greater the loudness. # Loudness Perception Loudness is strongly affected by the frequency of the signal. If intensity is held constant, a _mid-frequency signal_ (in the range from ~1000-4000 Hz) will be louder than lower or higher frequency signals. 125 Hz, 3000 Hz, 8000 Hz The 3000 Hz signal should appear louder than the 125 or the 8000 signal, despite the fact that their intensities are equal. # Loudness and Pitch - More sensitive to loudness at mid frequencies than at other frequencies - Intermediate frequencies at [500hz, 5000hz] - Perceived loudness of a sound changes based on the frequency of that sound. - Basilar membrane reacts more to intermediate frequencies than other frequencies. # Human Auditory Spectrum - < 20 Hz - infrasound - > 20 KHz - ultrasound - Human auditory range decreases with age - “Ultrasonic” cleaning devices, burglar alarms (20-40 KHz) - CD 20 KHz cutoff, vinyl 60-80 KHz # The Structure of the Auditory System An image was provided for this section, but it is not able to be displayed here. The image shows a cross-section of a human ear. The image highlights the pinna, auditory canal, tympanic membrane, ossicles, oval window, the auditory-vestibular nerve, and the cochlea. # The Auditory System An image was provided for this section, but it is not able to be displayed here. The image shows a cross-section of a human head with the ear highlighted along with the inner workings of the ear. The auditory nerve is shown leading from the inner ear to the brain. The illustration shows how the auditory nerve connects to the brain through a series of nuclei. # Central Auditory Processing An image was provided for this section, but it is not able to be displayed here. The image shows a cross-section of a human head with the auditory nerve leading into the brain. The image shows multiple pathways that the nerve can follow, highlighting that multiple areas of the brain will be involved in processing the signal. The image also shows a portion of the brain that is used in processing sound. The portion is outlined in green, purple and light-blue. The green outlined portion is labeled auditory, the purple outlined portion is labeled auditory and visual, and the light-blue portion is labeled A1. # Tonotopic Map in the Cortex An image was provided for this section, but it is not able to be displayed here. The first image in this section depicts the ear, superior olivary nucleus, cochlear nucleus, medial geniculate nucleus, and the auditory receiving area of the tempoal lobe. The second image highlights the core area, secondary auditory cortex, auditory association cortex and the temporal lobe. The third image is a diagram that depicts the frequency responsiveness of different parts of the brain. - The tonotopic relation is maintained in the auditory cortex as well (A1) - This figure indicates the locations of neurons that are responsive to particular frequencies (see the number - kHz) # Music Perception - Tone height: A sound quality whereby a sound is heard to be of higher or lower pitch; monotonically related to frequency. - Tone chroma: A sound quality shared by tones that have the same octave interval - Musical helix: Can help visualize musical pitch # Hierarchical Processing - Core→belt→Parabelt - Complex sounds are processed later - What vs. Where system: - Where: dorsal pathway→Sound localization - What: ventral pathway→Identifying sounds # Cross-modal plasticity in congenitally deaf An image was provided for this section, but it is not able to be displayed here. The images in this section are a series of scans of the brain. The scans are showing the increased activity found in the superior temporal gyrus in congenitally deaf subjects when they viewed signs or sign-like movements. The images highlight the plasticity that is possible when the brain adapts to its environment. - These PET/MR images show increased neural activity in the superior temporal gyrus in congenitally deaf subjects when they viewed signs or sign-like movements, suggesting that auditory cortical regions may contribute to the processing of visual information in the deaf. # Auditory Motion Perception - Early blind subjects show activation of visual cortex during an auditory motion tracking task. - Visual areas become involved in auditory processing. - Functional re-mapping of the cortex # Optic Nerve Hypoplasia - Sometimes referred to as ONH autism - Or DeMorsier's syndrome - Congenital blindness (optic nerve to one or both eyes impaired before birth) - Extremely sensitive to sound; for example have perfect pitch. - Musical savants can have ONH. # Video of a Musical Savant An image was provided for this section, but it is not able to be displayed here. The image shows a young boy playing a Yamaha keyboard. The boy is sitting on a red stool with a record player in the background. The image is intended to show the viewer that there are people in the world with exceptional abilities, such as the ability to create music. # Musical Savant An image was provided for this section, but it is not able to be displayed here. The image shows a dark-grey box with the words 'Musical Savant 16.4' written on the box in white. The image is intended to draw the viewer's attention to the fact that the following section is going to be about musical savants. # How is the brain of a gifted musician different? - Is it in the encoding? - Work from Nina Kraus's lab in Chicago: [http://www.soc.northwestern.edu/brainvolts/projects/clintech/soundwaves_demo.php](http://www.soc.northwestern.edu/brainvolts/projects/clintech/soundwaves_demo.php) - What else does musical training do to the brain? - Rhythm processing # Multisensory Perception: McGurk An image was provided for this section, but it is not able to be displayed here. The image shows a person with long, curly brown hair and glasses. The image is intended to introduce the McGurk Effect, where the viewer is presented with audio and visual stimuli that conflict in their perception. This often leads the person to hear something they don't see in the visual stimulus. # Music Perception - How do we have the ability to produce music? # Examples of Meter/Entrainment - Meters that are difficult to read: Gregorian chant and Stravinsky (Tarantella) - Rock and roll: 4/4 rhythm - Triple meter: Leonard Bernstein's America - Triple meter: with triple subdivision # Meet Snowball An image was provided for this section, but it is not able to be displayed here. The image shows a white cockatoo bird in a room with multiple cages in the background. The image is meant to highlight that animals are not just able to process sound, but can also entrain to a beat. For example, a cockatoo named Snowball can dance to different styles of music, similar to how a human would. # Meet Ronan the Sea Lion - [http://www.youtube.com/watch?v=6yS6qU_w3JQ](http://www.youtube.com/watch?v=6yS6qU_w3JQ) # One More Time... - Perception is essentially multisensory - While one sense could dominate another - Successful movement requires the processing of all of these senses.