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. Projects to investigate the development of ultrasonic call processing in mice are also being initiated to determine the relative contribution of genes and experience to vocalization representation in the cortex.

A second line of research is clinical in nature and involves the development of the visual system following developmental traumatic brain injury. The model system is the hamster which is suited for this line of study because of an interesting type of developmental plasticity. The removal of the caudal half of the hamster superior colliculus at birth results in a complete remapping of the visual field in the remaining rostral half. I am interested in the role of inhibition in this recovery process.

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 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.