Talk abstract:
Model Calculations of Steady State Responses
to Binaural Stimuli
in the Dorsal Nucleus of the Lateral Lemniscus
Jacob J. Blum
Department of Cell Biology
Duke University Medical Center
j.blum@cellbio.duke.edu
Several experimental studies have been performed in which
both the time-dependent and steady-state output of cells in
the dorsal nucleus of the lateral lemniscus (DNLL) have been
measured in response to binaural sound stimulation. In this
paper, a mathematical and computational model for the steady-state
output of DNLL cells is formulated. The model includes ascending
connections from both lateral and medial superior olives (LSO
and MSO) as well connections from inter-neurons in the DNLL
and connections from the contralateral DNLL through the Commissure
of Probst. Our intent is to understand how the steady-state
behavior arises from the cell properties in and connectional
patterns from lower brainstem nuclei. In particular, we examine
the connectional hypotheses put forward by Markovitz and Pollak
(1994) to explain the observed behavior of EI, EI/F, EE/I, and
EE/FI cells. Using these connections (with minor modifications)
and cells with very simple input-output relations, we are able
to account for the steady-state behavior of these cell types.
Further, we are able to explain interesting features of the
data not commented on before, for example the initial dip in
spike output for EE cells at low ipsilateral sound levels. The
presence of an inhibitory interneuron in the DNLL plays is essential
for facilitation. In addition, we perform a preliminary inve!
stigation of the effects of the MSO and the Commissure of Probst
on DNLL output. Although there is no experimental evidence for
a topographic place map in the inferior colliculus , we propose
a simple mechanism by which the cells of the DNLL and LSO could
create such a map.
Back to Workshop Schedule
1998-1999
Mathematics in Biology
