HST 722 / 9.044“Brain Mechanisms in Hearing and Speech”

Course Introduction• Course Web Site (explains everything):

http://web.mit.edu/hst.722/www/index.html• An advanced course covering anatomical, physiological, behavioral, and

computational studies of the central nervous system relevant to speech and hearing.

• Students learn primarily by discussions of scientific papers on topics of current interest. A topic usually consists of one lecture & two class periods devoted to discussions of papers.

• Grade and Assignments: – Paper presentations, discussion leading and class participation, 65% – Written & oral assignments associated with Student-chosen Topics, 35%

Course Topics• Dorsal cochlear nucleus: Signal processing, multisensory integration and

plasticity (Hancock)• Quantitative approaches to the study of neural coding (Delgutte)• Speech motor control (Guenther)• Descending Systems (Brown)• Neuroimaging correlates of human auditory behavior / multisensory

integration (Melcher)• Student Topics: Initial Presentations• Language processing I: Cortical representation (Caplan)• Language processing II: Auditory Processing Disorders (Melcher and

others)• Student Topics: Final Presentations

Most auditory nuclei are located near dorsal surface of brainstem

Aitkin (1986)

Auditory Structures• 8N: 8th Nerve• CN: Cochlear Nucleus• LL: Lateral Lemniscus• IC: Inferior Colliculus• SC: Superior Colliculus• ICO: Commissure of IC• BIC: Brachium of IC• MGB: Medial Geniculate

Body• AI: Primary Auditory

CortexOther Structures• ICM: Cerebellum• 5N; Trigeminal Nerve

Cat

The ascending auditory pathway

Descending pathway roughly parallels ascending pathway

N

PVCN

N

I.C.

Somatosensory

TD

??

granule

giantt

fusiform

auditorynerve

stellategolgi

cartwheel

vertical

Dorsal cochlear nucleus: Signal processing, multisensory integration and plasticity (Hancock)

Complex circuitry of the Dorsal Cochlear Nucleus:

DCN Layers:I

II

III (IV,V)

0 20 40 60 80 1000

500

1000

0 20 40 60 80 1000

10

20

30

Intensity (dB SPL)

Dis

char

ge ra

te

(sp/

sec)

Inte

nsity

DL

(dB

) Auditory-nerve fibeHypothetical neuron verifying Weber’s law

Quantitative methods for studies of neural coding (Delgutte)

Signal detection theory allows rigorous comparisons between neurophysiological and psychophysical data

Descending Systems (Brown)

From Schofield and Coomes (2005)

Speech motor control (Guenther)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Neuroimaging correlates of human auditory behavior (Melcher)

From Petrides and Pandya (1988)

Right

Left

ResponseIncreaseto Music

ResponseDecrease

Laterobasal

Superficial

Centromedial

Amygdala Subregions

Neuroimaging correlates of human auditory behavior (Melcher)

From Ball et al. (2007)

Language processing I: Cortical representation (Caplan)

From Caplan and Gould (2003)

Student Topics• Initial Presentations (about mid-way through the course)

– Each student chooses, writes up (about 6 pages), and defends orally (10 min. presentation) a topic germane to hearing / speech

– Propose 3-4 papers on this topic that could be discussed at the Final Presentations

– We will vote on which several topics to choose for the Final Presentations

• Final Presentations (at end of the course)– Each winning topic is presented by a group of students – The group presents the topic and leads the discussion of the papers

• Example Student Topics have been Absolute Pitch, Auditory Short-Term Memory, A Gene for Speech?, and Auditory Learning in Songbirds

Dorsal Cochlear Nucleus Papers

Discussed 9/13:1. May BJ. Role of the dorsal cochlear nucleus in the sound localization behavior of cats. Hear Res 148: 74-87 (2000). 2. Young ED, Spirou GA, Rice JJ, Voigt HF. Neural organization and responses to complex stimuli in the dorsal cochlear nucleus. Phil Trans Roy Soc London B336:407-413 (1992)3. Kanold PO, Young ED. Proprioceptive information from the pinna provides somatosensory input to cat dorsal cochlear nucleus. J Neurosci 21: 7848-7858 (2001).

Discussed 9/18:4. Tzounopoulos T, Kim Y, Oertel D, Trussell LO. Cell-specific, spike timing-dependent plasticities in the dorsal cochlear nucleus. Nat Neurosci 7:719-725 (2004).5. Bell CC. Memory-based expectations in electrosensory systems. Curr OpinNeurobiol 11: 481-487, 2001.6. Levine RA. Somatic (craniocervical) tinnitus and the Dorsal Cochlear Nucleus hypothesis. Am J Otolaryngol. 20:351-362 (1999)