Model - Deep nuclear neurons
    Deep nuclear neurons represent the final output of cerebellum after integrating afferent excitatory pontine inputs and inhibitory input from cerebellar cortical Purkinje cells. These cells spontaneously discharge at rest but can respond to Purkinje cell inhibition with a transient rebound burst discharge. My project involves the use of patch clamp recordings and stimulation of synaptic inputs to understand the regulation and functional role of burst output in response to physiological patterns of input.

Distinct ion channel contributions to burst phenotype in deep cerebellar neurons
    The large diameter putative projection neurons of rat deep cerebellar nuclei have been shown to generate either a Transient or Weak rebound Burst phenotype that was linked to the selective expression of T-type calcium channel isoforms. Here we show that the two burst phenotypes also reflect a differential functional availability of LVA T type calcium current at burst threshold, and different contributions of repolarizing potassium currents that shape burst properties. See Molineux et al. (2008). PDF

Distinct roles for IT and IH in controlling deep cerebellar rebound responses
   Here we examined the role for IT and IH in generating the rebound responses that are evoked in deep cerebellar neurons in response to inhibitory input from Purkinje cells. We used recordings in vitro and modeling to find that only a small fraction of the total IT and IH available to a cell are activated by physiological levels of hyperpolarization. However, the currents activated are still sufficient to differentially control the latency, frequency and precision of spike firing during the immediate phase of a rebound response. See Engbers et al. (2011).

Peer-reviewed Publications

Iftinca, M., Hamid, J., Chen, L., Varela, D., Tadayonnejad, R., Altier, C., Turner, R.W. and Zamponi, G.W. (2007) Regulation of T-type calcium channels by Rho-associated kinase. Nature Neuroscience 10 (7): 854-860. PDF

Molineux, M.L., Mehaffey, W.H., Tadayonnejad, R., Anderson, D., Tennent, A.F. and Turner, R.W. (2008) Ionic factors governing rebound burst phenotype in rat deep cerebellar neurons. J. Neurophysiology 100:2684-2701. PDF

Tadayonnejad, R., Mehaffey, W.H., Anderson, D. and Turner, R.W. (2009) Reliability of triggering postinhibitory rebound bursts in deep cerebellar neurons. Channels 3(3): 149-155. Open Access.

Engbers, J.D.T.*, Anderson, D.*, Tadayonnejad, R.*, Mehaffey, W.H., Molineux, M.L. and Turner, R.W. (2011) Distinct roles for IT and IH in controlling the frequency and timing of rebound spike responses. J. Physiol (Lond.), eprint, Oct 3, 2011. * Shared first authors.



Invited Chapters

McKay, B.E., Tadayonnejad, R., Anderson, D.M., Engbers, J.D.T., Fernandez, F.R.,  and Turner, R.W. (2010)  Establishing in vivo like activity in rat cerebellar cells maintained in vitro. Isolated Neural Circuits, in Neuromethods (Ballanyi, K., ed.), Springer In Press.

Tadayonnejad, R., Anderson, D., Molineux, M.L., Mehaffey, W.H., Jayasuriya, K. and Turner, R.W. Rebound discharge in deep cerebellar nuclear neurons in vitro. Cerebellum 9(3):352-74. PDF

Abstracts - Published work

Iftinca M, Hamid J, Tadayonnejad R, Turner RW, Zamponi GW ROCK-mediated inhibition of T-type calcium channels. Biophys Soc. 2007.

Tadayonnejad, R., Molineux, M.L., Mehaffey, H.M. and Turner, R.W. Transient and Weak Bursting Deep Cerebellar neurons exhibit differential coding properties for membrane hyperpolarizations. Proc. Soc. Neurosci. 2007.

Tadayonnejad, R., Mehaffey, W.H., Jayasuriya, K. and Turner, R.W. Rate and temporal coding properties of deep cerebellar neurons. Can. Assoc. Neurosci. 2008.

Tadayonnejad, R., Mehaffey, W.H., Jayasuriya, K. and Turner, R.W. Deep cerebellar nuclear neurons use different strategies for coding physiological patterns of Purkinje cell activity. Proc. Soc. Neurosci. 2008.

Tadayonnejad, R., Mehaffey, W.H., Jayasuriya, K. and Turner, R.W. Rebound burst phenotypes in Deep Cerebellar Nuclear cells define the response to synaptically evoked membrane hyperpolarizations. Can. Assoc. Neurosci., 2009.

Jayasuriya, K., Tadayonnejad, R. and Turner, R.W. Ionic determination of first spike latency in Deep Cerebellar Nuclei by HCN channels. Can Assoc. Neurosci., 2009.

Tadayonnejad, R., Mehaffey, W.H. and Turner, R.W. Rate and temporal neural codes in deep cerebellar neurons translate Purkinje cell inhibitory input. IUPS, Kyoto 2009.

Tadayonnejad R, Engbers J, Anderson D, Mehaffey, WH and Turner RW. The role of IH and IT in controlling rebound burst properties of Deep Cerebellar Nuclear cells. Can Assoc. Neurosci., 2010.

Tadayonnejad R, Engbers JDT, Anderson D, Mehaffey WH and Turner RW. IT and IH selectively regulate rate coding and spike precision in deep cerebellar nuclear cells. Proc. Soc. Neurosci., 2010.