Faculty » Khaleel A. Razak

I am interested in the development of sensory processing. Current projects in the lab focus on the development of both sound localization and echolocation behaviors in the pallid bat. The pallid bat belongs to a small group of bats called gleaners. While hunting, it uses echolocation to avoid obstacles and passive sound localization to locate terrestrial prey. Using single and multi-electrode recordings, tract tracing, neuropharmacology and behavioral analyses, I seek to understand development of the mechanisms underlying echolocation and passive sound localization.

My lab also studies the mouse auditory cortex to determine relative contributions of genetic and experience-driven factors underlying plasticity of complex sound representation. The following are current specific projects:

1. How does representation of frequency modulated (FM) sweeps change in a mouse model of age-related hearing loss?


2. Is there an auditory processing deficit in a mouse model of Fragile X Syndrome?


3. How does the representation of FM sweeps change during development, and does augmenting experience with sweeps affect developmental trajectory of sweep representation?

Students interested in taking an integrative approach to sensory processing and neural development are welcome to join my lab either through the Department of Psychology or through the Graduate Neuroscience Program.

I also strongly encourage undergraduate student research in my lab.

Selected Publications

Razak KA. Systematic representation of sound locations in the primary auditory cortex. J. Neurosci. In Press.

Trujillo M, Measor K, Carrasco, MM and Razak KA. Selectivity for the rate of frequency modulated sweeps in the mouse auditory cortex. J. Neurophysiol. In Press.

Razak KA and Fuzessery ZM. Development of parallel auditory thalamocortical pathways for two different behaviors. In press, Frontiers in Neuroanatomy.

Razak KA and Fuzessery ZM. Experience-dependent development of vocalization selectivity in the auditory cortex. J. Acoust. Soc. Am., 128(3):1446-1451, 2010.

Razak KA and Fuzessery ZM. GABA shapes a systematic map of binaural sensitivity in the auditory cortex. J. Neurophysiology 104: 517 – 528, 2010.

Razak KA and Fuzessery ZM. GABA shapes selectivity for the rate and direction of frequency modulated sweeps in the auditory cortex. Journal of Neurophysiology 102:1366-1378, 2009.

Razak KA, Zumsteg, T and Fuzessery, ZM. Development of auditory thalamocortical connections in the pallid bat, Antrozous pallidus. Journal of Comparative Neurology 515:231-242, 2009.

Razak KA and Fuzessery ZM. Facilitatory mechanisms underlying selectivity for frequency modulated sweeps in the auditory cortex. J. Neurosci. 28:9806-9816, 2008.

Razak KA, Richardson, MD and Fuzessery, ZM. Experience is required for the maintenance and refinement of FM sweep selectivity in the developing auditory cortex. Proc. Natl. Acad. Sci. (USA) 105:4465-4470, 2008.

Razak KA and Pallas SL. Inhibitory plasticity facilitates recovery of stimulus velocity tuning in the superior colliculus after chronic NMDA receptor blockade. J. Neurosci. 27:7275-7283, 2007

Razak KA and Fuzessery ZM. Development of inhibitory mechanisms underlying selectivity for the rate and direction of frequency-modulated sweeps in the auditory cortex. J. Neurosci. 27:1769-1781, 2007.

Razak KA and Fuzessery ZM. Development of functional organization of the pallid bat auditory cortex. Hearing Res. 228:69-81, 2007.

Razak KA, Shen W, Zumsteg, T and Fuzessery, ZM. Parallel thalamocortical pathways for echolocation and passive sound localization in a gleaning bat, Antrozous pallidus. J. Comp. Neurol. 500:322-338, 2006.

Pallas SL, Wenner P, Gonzales-Islas C, Fagiolini M, Razak KA, Kim G, Sanes D and Birgit, R. Developmental plasticity of inhibitory circuitry. J. Neurosci. 26:10358-10361, 2006.

Razak KA and Pallas SL. Dark rearing reveals the mechanism underlying stimulus size tuning of superior colliculus neurons. Vis. Neurosci. 23:741-748, 2006.

Razak KA and Fuzessery ZM. Neural mechanisms underlying selectivity for the rate and direction of frequency- modulated sweeps in the auditory cortex of the pallid bat.
J. Neurophysiol. 96:1303-1319, 2006.

Razak, KA and Pallas SL. Neural mechanisms of stimulus velocity tuning in the superior colliculus. J. Neurophysiol. 94:3573-3589, 2005.

Carrasco MM, Razak KA and Pallas SL. Visual experience is necessary for maintenance but not development of refined retinotopic maps in superior colliculus. J. Neurophysiol. 94: 1962-1970, 2005.

Razak KA, Huang L and Pallas SL. Chronic NMDA receptor blockade increases receptive field size without affecting stimulus velocity or size tuning of superior colliculus
neurons. J. Neurophysiol. 90(1): 110-119, 2003.

Barber JR, Razak KA and Fuzessery ZM. Can two streams of auditory information be processed simultaneously? Evidence from the gleaning bat Antrozous pallidus. J. Comp. Physiol. A 189: 843-855, 2003.

Razak KA and Fuzessery ZM. Functional organization of the pallid bat auditory cortex: emphasis on binaural organization. J. Neurophysiol. 87(1): 72-86, 2002.

Razak KA and Fuzessery ZM. A systematic representation of interaural intensity differences in the auditory cortex of the pallid bat. NeuroReport 11(13): 2919-2924, 2000.

Razak KA, Fuzessery ZM and Lohuis T. Single neurons respond to both active and passive sounds in the pallid bat auditory cortex. J. Neurophysiol. 81(3): 1438-1442, 1999.

Book Chapters

Razak KA, Fuzessery, ZM, Carrasco MM and Pallas, SL. Developmental plasticity of inhibitory receptive field properties in the auditory and visual systems. In: Pallas,
SL and Wenner, P (eds). Developmental plasticity of inhibitory circuits. Springer (In review).

Pallas SL, Xu M and Razak KA. Influence of thalamocortical activity on sensory cortical development and plasticity. In: R. Erzurumlu, W. Guido, Z. Molnar, (eds.) Development and Plasticity in Sensory Thalamus and Cortex. Kluwer Academic/ Plenum Publishers, New York. 2005.