Administration Basic Sciences Clinical Sciences Centers of Excellence
Department Title
Spotlight Section New Orleans
 

Hamilton Farris, PhD

Assistant Research Professor,
Otorhinolaryngology and Neuroscience
 

2020 Gravier St.
New Orleans, LA 70112

Phone: 504-599-0865

hfarri@lsuhsc.edu

Lab Web Page (under construction)

 

 

 

Degrees

 

2002-2006: Postdoc, LSUHSC

2000-2002: Postdoc, University of Texas-Austin

1994-2000: PhD, Cornell University (Neurobio. & Behavior)

1992-1994: MSc, University of Mississippi (Biology)

1987-1992: BA, University of Mississippi (Biology)

 

Bio

Awards/Recognitions/Lectures:

2005-2006: NRSA Individual Postdoctoral F32 Fellowship LSUHSC

2003-2005: NRSA Individual Postdoctoral F32 Fellowship LSUHSC

1998: Best Student Paper; 16th International Congress on Acoustics and the 135th meeting of the Acoustical Society of America. Seattle, WA. USA

1995- 2000: NIMH integrative training grant fellowship, Cornell University   

 

Research Interest: Using the methodologies of psychophysics and neurophysiology, our research explores the underlying neural mechanisms mediating sensory acuity (i.e., stimulus detection and discrimination).

Bio: Dr. Farris completed his undergraduate and Masters degrees in Biology at the University of Mississippi (1992, 1994). For his masters degree he conducted research at the National Center for Physical Acoustics. Using a comparative approach, that work discovered the first evidence for hearing in certain insects and showed that insect auditory systems process certain sounds like humans do.
  For his PhD in Neurobiology and Behavior at Cornell University (2000), Dr. Farris received a fellowship from the National Institute of Mental Health to continue research using insects as comparative models for the mechanisms of audition, including across channel processing, loudness perception, temporal integration and intensity discrimination. Insect ears are presently being used as models for engineering new, more effective hearing aid products. Dr. Farris continues collaboration on such small eared systems in hopes of developing such therapeutic devices.
  Dr. Farris was a post-doctoral fellow in Integrative Biology at the University of Texas-Austin (2000-2002), where research examined the mechanisms of complex auditory processing in a unique clade of frogs. Few animals use complex speech-like communication signals, making most animal systems poor models for elucidating neural correlates of speech perception. The calls of Tungara frogs, however, are acoustically similar to human consonants and vowels. Research showed that complex processing such as auditory grouping and syntax are important in this system, suggesting that these frogs will make an excellent model system for studying speech processing and its pathologies.
  Dr. Farris returned to New Orleans in 2002, as a post-doctoral fellow at the Center for Neuroscience, LSUHSC (2002-2006). Research for this fellowship focused on the mechanisms of hair cell mechano-electric transduction. In particular, using patch-clamping techniques, research investigated the pharmacological identity of the transduction channeland  the role of endolymph in producing the set point of hair cells and the role of calcium loading in hair cell stereocilia in producing sensitivity loss and threshold shifts. This research continues presently at LSUHSC, as he was promoted to Assistant Professor-Research (2006).

Clinical Interests

Current Research:

Descending modulation of attention to complex auditory stimuli:
By integrating the approaches and methodologies of neurophysiology and psychophysics, Dr. Farris’ research has addressed the spatial, temporal and spectral limits of perceptual grouping of speech-like sounds; the effect of loudness on two-tone suppression and lateral inhibition; the measurement and function of the unique ionic properties of endolymph in the vertebrate cochlea and the pharmacological profile of the hair cell mechanoelectric tranducer channel. Dr. Farris’ lab is presently focused on the top-down mechanisms of attention, in which the salience of particular incoming stimuli is biased by descending forebrain activity.
  We use an animal model in which speech-like sounds are behaviorally relevant, there is a robust bioassasy for attention, and the brain is readily accessible through electrophysiological and molecular-marking techniques. Male túngara frogs produce a complex call composed of two speech-like components: the vowel-like FM sweep called the “whine” and the consonant-like broadband “chuck” (see spectrograms in figure). All calls contain a whine, which is necessary and sufficient to elicit phonotaxis. Chucks are only produced following a whine, creating a natural syntax. Although the chuck alone does not elicit a behavioral response, it captures attention when broadcast with a whine; a similar switch to that found in disorders such as ADD, where attention to speech is “switched on or off”. Furthermore, hormone treatments show that attention to these calls is developmentally plastic, suggesting steroidal modulation of reward/attention circuitry. The response properties of midbrain (IC) and thalamic nuclei in frogs may be modulated with dopaminergic input and the functional circuitry may undergo remodeling with auditory experience. Thus the complex auditory signals in túngara frogs and their tractable auditory nuclei make them excellent models for elucidating the mechanisms of attention during speech-like processing.

Research Interests

Keywords:
speech, attention deficit disorder, complex auditory stimuli

Our long-range goal is to understand how components of the descending reward-attention circuitry contribute to auditory plasticity and to apply this knowledge to mitigate pathological attention deficit towards speech.

Teaching Activities

Links:

Inter 132

2007 – present: Assistant Research Professor of Otorhinolaryngology, and Neuroscience; Neuroscience Center, LSU Health Sciences Center, New Orleans, LA   

2001- present Visiting Scientist; Smithsonian Tropical Research Institute (Panama)

2002 -2006: Postdoctoral fellow; Neuroscience Center, LSU Health Sciences

2000-2002: Postdoctoral fellow; Univ. Texas-Austin; Integrative Biology

Selected Publications

 

Recent Papers:

Farris, H.E., Oshinsky, M., Forrest, T., and Hoy, R.R. (2008) Auditory sensitivity of an acoustic parasitoid (Emblemasoma sp., Sarcophagidae, Diptera) and the calling behavior of potential hosts. Brain , Behavior and Evolution, 72:16-26.

Farris, H.E., Wells, G.B. and Ricci, A.J. (2006) Steady-state adaptation of mechanotransduction modulates the resting potential of auditory hair cells, providing an assay for endolymph [Ca2+]. Journal of Neuroscience. 26, 12526-12536.

Farris, H.E., Rand, A.S. and Ryan, M.J. (2005) The effects of time, space and spectrum on auditory grouping in túngara frogs. Journal of Comparative Physiology A. 191, 1173-1183.

Farris, H.E., and Ricci, A.J. (2005) Voltage-clamp errors cause anomalous interaction between independent ion channels. Neuroreport, 16, 943-947.

Witte, K., Farris, H.E., Ryan, M. andWilczynski, W. (2005) How cricket frog females deal with a noisy world: habitat-related differences in auditory tuning. Behavioral Ecology, 16, 571–579.

Farris, H.E., LeBlanc, C.L., Goswami, J. and Ricci, A.J. (2004) Probing the pore of the auditory hair cell mechanotransducer channel in turtle. Journal of Physiology, 558.3, 769-792.

Wyttenbach, R. and Farris, H.E. (2004) Insect psychoacoustics. Microscopy Research and Technique, 63, 375-387.

Farris, H.E., Mason, A.C. and Hoy, R.R. (2004) Identified auditory neurons in the cricket Gryllus rubens: temporal processing in calling song sensitive units. Hearing Research,193, 121-133.

Farris, H.E., Rand, A.S. and Ryan, M.J. (2002). The effects of spatially separated call components on phonotaxis in túngara frogs: Evidence for auditory grouping. Brain, Behavior and Evolution.60, 181-188.

Additional Info

Dr. Farris' Curriculum Vitae

Lab Web Page (under construction) 

Present Funding:
2007-2012 Investigator, CoBRE
(Center of Biomedical Research Excellence) NIH
Title: Mentoring Neuroscience in LA: A biomedical Program to Enhance Neuroscience
Grant # P20RR016816 (N. Bazan, PI)

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