Rhythm and Rate: Perception and Physiology HST 722 - November 27 Jennifer Melcher
Forward suppression of unit activity in auditory cortex Brosch and Schreiner (1997) J Neurophysiol 77: 923-943.
Forward facilitation of unit activity in auditory cortex Brosch and Scheich (Epub ahead) Exp Brain Res.
Forward suppression of auditory evoked cortical potentials 5. Butler (22) J Neurophysiol 88: 1433-145.
Blood Oxygenation Level-Dependent fmri Brain ctivity Increase Metabolic Response Blood Flow Increase Blood Oxygenation Increase Image Signal Increase
Time Course of fmri ctivation: n Example Sound On Percent Signal Change 1 3 Time (seconds)
Human uditory Pathway uditory Cortex Medial Geniculate Body Inferior Colliculus Superior Olivary Complex Superior Olivary Complex uditory Cortex Medial Geniculate Body Inferior Colliculus Cochlear Nucleus Cochlear Nucleus Diagram of human auditory pathway from cochlea to cortex. Montage of images showing sound-evoked fmri activation in the auditory pathway. fmri activation (color scale) is superimposed on anatomical images (grayscale) intersecting different parts of the pathway. 7
Stimulation paradigm for following slide. Stimuli Stimuli Off On (3 s) (3 s) time Noise Burst
Different Dependencies on Sound Repetition Rate in Midbrain and Cortex 35/s Inferior Colliculus (Exp. I) Subject 3 Subject 5 p=.1 R L 35/s R Subject 3 uditory Cortex (Exp. I) L Subject 5 p=2x1-9 Heschl's Gyrus Superior Temporal Gyrus 1/s 1/s 5 mm 2/s Inferior Colliculi 2/s Figure 3: ctivation maps for the IC (two subjects, Exp. I). Stimuli were noise burst trains with repetition rates of 2, 1, or 35/s. Each panel shows a T1-weighted anatomic image (grayscale) and superimposed activation map (color) for a particular subject. Rectangle superimposed on the diagrammatic image (bottom, right) indicates the area shown in each panel. For the activation maps, regions are colored according to the result of a t-test comparison of image signal strength during train on and off periods. In this and all subsequent figures, blue and yellow correspond to the lowest (p =.1) and highest (p = 2 x 1-9 ) significance levels, respectively. (reas with p >.1 are not colored). ctivation maps (based on functional images with an in-plane resolution of 3.1 x 3.1 mm) have been interpolated to the resolution of the anatomic images (1.6 x 1.6 mm). Images are displayed in radiological convention, so the subject's right is displayed on the left. R, right; L, left. 1/s 1 cm Figure 7: ctivation maps for HG and STG (two subjects, Exp. I). Stimuli were noise burst trains with repetition rates of 1, 2, 1, or 35/s. See Figure 3 caption. Harms and Melcher (22) J Neurophysiol 88: 1433-145.
Different Dependencies on Sound Repetition Rate in Midbrain and Cortex 2/s 1/s 35/s 2. 1 uditory Cortex Inferior Colliculus Percent Signal Change 2. Sound On 3 3 Time (seconds) 3 Harms and Melcher (22) J Neurophysiol 88: 1433-145.
Wide Range of ctivation Waveshapes in uditory Cortex Percent Signal Change (Normalized) 1 1 2/s Noise Bursts Sound On Music Running Speech 1/s Noise Bursts Continuous 35/s Noise 35/s Clicks Noise 1/s Clicks Bursts sustained phasic 3 3 3 Time (seconds) 3
Sensitivity of ctivation Waveshape to Sound Temporal Envelope Characteristics sustained phasic Percent Signal Change 1 Time (seconds) Time (seconds) Increasing Modulation Rate Increasing Sound Time Fraction Harms et al. (25) J Neurophysiol 93: 21-222.
Insensitivity of ctivation Waveshape to Sound Level Waveshape vs Level 35/s noise bursts Waveshape vs Rate 7 db SL Percent Signal Change 2 7 db SL 55 db SL 4 db SL 2/s 35/s 3 3 Time (s) Time (s) Harms et al. (25) J Neurophysiol 93: 21-222.
fmri response waveshape in auditory cortex is sensitive to sound temporal envelope characteristics. insensitive to sound level and bandwidth.
Harms and Melcher (22) J Neurophysiol 88: 1433-145.
Responses in a waking patient to repetitive binaural clicks at various rates. In sections and B are responses to clicks at low rates, similar to those evoked by single clicks. Sections C, D and E show for higher stimulation rates the sequence: onresponse, driving response, and off-response. In section F the driving response has practically disappeared, while the onresponse and off-response persist unchanged. The estimated location of the responding electrode is indicated as number 1 in figure 1. Chatrian et al. (196) Electroenceph. Clin. Neurophysiol. 12: 479-489.
The waveshape of cortical activation may also reflect perceptual aspects of a sound. Many Successive Sounds Heard One Sound Heard Percent Signal Change 1 sustained Time (seconds) phasic Time (seconds) The beginning and end of auditory objects may be delimited by distinct peaks in population neural activity of auditory cortex.
Harms and Melcher (22) J Neurophysiol 88: 1433-145.
Underlying Neurophysiology Forward Suppression Percent Signal Change 1 Neural Off Response Time (seconds)
ctivation Waveshape cross Levels of the uditory Pathway 1 uditory Cortex Normalized Percent Change 1 1 1 Medial Geniculate Body Inferior Colliculus Superior Olivary Complex 1 Cochlear Nucleus 3 Time (s)
Human uditory Cortex: Spatial Variations in ctivation Waveshape lateral more phasic more sustained posterior Normalized Percent Change 1 3 Time (s) Heschl s Gyrus Planum Temporale
Frequency 1 stream gallop B B Time From HST 723 lecture of Christophe Micheyl, Spring 26.
Frequency B B Δf Time
Frequency 2 streams! one high and slow, the other low and fast B B Time
Frequency B B Time
Neuromagnetic Responses from Human uditory Cortex Gutschalk et al. (25) J. Neurosci. 25: 5382-5388.
Neuromagnetic Responses from Human uditory Cortex For Stimulus Producing a Bistable Percept Gutschalk et al. (25) J. Neurosci. 25: 5382-5388.
Mismatch Negativity: Dependent on Stimulus Context "Mismatch Negativity" - or MMN - occurs in response to deviant" stimuli in oddball paradigm - can occur even when the subject is not attending to the stimuli - dependent on stimulus modality (e.g. auditory vs. visual) Oddball Paradigm: standard stimulus deviant stimulus time Figure 1: Stylized EP in humans. The illustration is modeled after responses to brief stimuli recorded between two electrodes: at the vertex or top of the head and near the stimulated ear (inset at top right). Stimulus presentation is at msec (at arrow in top waveform). Bottom: Entire EP is shown: BR (green), MLR (red), and LLR (blue). Top: The BR has been expanded so its individual components can be resolved. The dashed trace indicates how the response to the same stimulus would differ if presented as the deviant stimulus in an oddball paradigm. The dashed waveform, minus the solid, is the MMN. Melcher (in press) uditory Evoked Potentials. In: New Encyclopedia of Neuroscience. Ed. L. Squires. Elsevier.
Plan for discussion sessions for Neuroimaging Correlates of uditory Behavior Tuesday November 27: (1) Wehr & Zador (25) Synaptic mechanisms of forward suppression in rat auditory cortex. Neuron 47: 437-445. (2) Tubau et al. (27) Individual differences in sequence learning and auditory pattern sensitivity as revealed with evoked potentials. Eur J Neurosci. 26: 261-264. (3) Becker & Rasmussen (27) The rhythm aftereffect: support for time sensitive neurons with broad overlapping tuning curves. Brain and Cognition 64: 274-281. (4) 1 discussion question, to be answered by all, but with one person designated discussion leader Thursday November 29: (5) Wilson et al. (27) Cortical fmri activation to sequences of tones alternating in frequency: relationship to perceived rate and streaming. J Neurophysiol. 97: 223-2238. (6) Micheyl et al. (25) Perceptual organization of tone sequences in the auditory cortex of awake macaques. Neuron 48: 139-148. (7) 2 discussion questions