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Iwona Stepniewska

Research Assistant Professor of Psychology

Iwona Stepniewska studies anatomical and functional organization of motor and sensory systems in primates.

Current Research

  • Posterior parietal cortex and complex motor behavior. The goal of this project is to better understand involvement of posterior parietal cortex in motor behavior. The dominant view of function is that posterior parietal cortex uses visual, somatosensory, and auditory inputs to guide eye and limb movements in space. However, few subdivisions are well defined, and connection patterns are only broadly understood. We use intracortical microstimulation technique (motor mapping) to delivered trains of electrical pulses via microelectrodes to define and describe the major movement zones in posterior parietal cortex of anesthetized monkeys and galagos and study connections of these zones with other areas and subcortical nuclei, especially with premotor cortex. The results will provide new insights into the functional organization of posterior parietal cortex, and how functions are mediated via differing connection patterns, epecially with motor fields.
  • Distribution of sascending somatosensory pathways . The organization and connection patterns of two main ascending somatosensory pathways (dorsal column-medial lemniscus and spinothalamic tracts) that convey information from the skin, joints or muscles receptors to higher brain centers have not been fully understood. By injecting dorsal column nuclei and spinal cord with different tracers we study their projections to sensorimotor thalamus. Results will improve our understanding of the processing of somatosensory information, and the ways in which each of these main subcortical somatosensory structures interact with other somatosensory processing stations.
  • Anatomical substrates for movement controlThe major goal of the project is to understand the interface between the basal ganglia output nuclei and the cerebellum in the production of coordinated goal directed movements. The focus is on the sources of input to the different areas in the motor cortical region in primates using anatomical tract tracing methods.

Representative Publications

Stepniewska I, Friedman RM, Gharbawie OA, Cerkevich CM, Roe AW, Kaas JH (2011) Optical imaging reveals parietal-frontal circuits underlying motor behavior. PNAS (accepted).

Gharbawie OA, Stepniewska I, Qi H-X, Kaas JH. (2011) "Multiple parietal-frontal pathways mediate grasping in macaque monkeys". J Neurosci. (accepted).

Kaas JH, Gharbawie OA, Stepniewska I (2011) The organization and evolution of dorsal stream multisensory motor pathways in primates. Front Neuroanat. 5:34. Epub 2011 Jun 13.PMID:21716641[PubMed].

Gharbawie OA,Stepniewska I, Kaas JH (2011) Cortical connections of functional zones in posterior parietal cortex and frontal cortex motor regions in New World monkeys. Cereb Cortex Jan 24. [Epub ahead of print] PMID:  21263034

Stepniewska I, Fang, P-C, Kaas JH. (2009) Organization of the posterior parietal cortex in prosimian Galago: I. Functional zones identified by microstimulation J Comp Neurol 517:765-782.

Stepniewska I, Fang P-C, Cerkevich C., Kaas JH (2009) Organization of the posterior parietal cortex in prosimian Galago: II. Ipsilateral cortical connections of sensori-motor region. J Comp Neurol 517:783-807.

Pouget P, Stepniewska I, Leslie M, Emeric E, Nelson M. Schall JD (2009) Visual and motor connectivity and the distribution of calcium-binding proteins in macaque frontal eye field: implications for saccade target selection. Front Neuroanat 3:2.

Stepniewska I, Preuss TM, Kaas JH (2007) Thalamic connections of the dorsal and ventral premotor areas in New World owl monkeys. Neuroscience 147:727-745.

Stepniewska, I, Preuss, TM and J.H. Kaas (2005) Ipsilateral cortical connections of dorsal and ventral premotor areas in New World owl monkeys. J Comp Neurol. 495:691-708.

Stepniewska I, Fang P-C, Kaas JH (2005) Microstimulation reveals specialized subregions for different complex movements in the posterior parietal cortex of prosimian primates. PNAS 102:4878-4883

Stepniewska, I,Collins CE, Kaas JH (2005) Reappraisal of DL/V4 boundaries based on connectivity patterns of dorsolatearl visual cortex in macaques.  Cereb Cortex 15(6):809-22.

Stepniewska I (2004) The pulvinar complex. In: The primate visual system. CRC Press LLC. (Eds.) J.H. Kaas and C.E. Collins., pp.53-80.

Stepniewska I, Sakai ST, Qi HX, Kaas JH (2003) Somatosensory input to the ventrolateral thalamic region (VL) in the macaque monkey: a potential substrate for parkinsonian tremor. J Comp Neurol 455:378-395

Kaas JH, Stepniewska I  (2002) Motor cortex. In: Encyclopedia of the human brain. Academic Press. (ed. V.S. Ramachandran)

Stepniewska I, Qi HX, Kaas JH (2000) Projections of the superior colliculus to subdivisions of the inferior pulvinar in New World and Old World monkeys.  Vis. Neurosci. 17:1-21.

Stepniewska I, Qi H-X, Kaas JH (1999) Do superior colliculus projection zones in the inferior pulvinar project to MT in primates? Eur. J. Neurosci. 1: 101-112.

Preuss TM, Stepniewska I, Kaas JH (1996) Movement representation in the dorsal and ventral premotor areas of owl monkeys: A microstimulation study. J. Comp. Neurol. 371:649-676.

Stepniewska I, Preuss TM, Kaas JH (1993) Architectonics, somatotopic organization and ipsilateral cortical connections of the primary motor area (M1) of owl monkeys. J. Comp. Neurol. 329:1-34.