Biomedical Engineering Reference
In-Depth Information
6.
The burst firing in the ipsilateral EBN causes the burst in the ipsilateral Abducens
Nucleus, which then stimulates the ipsilateral lateral rectus muscle and the contralateral
Oculomotor Nucleus. With the stimulation of the ipsilateral lateral rectus muscle by the
ipsilateral Abducens Nucleus and the inhibition of the ipsilateral rectus muscle via the
Oculomotor nucleus, a saccade occurs in the right eye. Simultaneously, the contralateral
medial rectus muscle is stimulated by the Contralateral Oculomotor Nucleus, and with
the inhibition of the contralateral lateral rectus muscle via the Abducens Nucleus, a
saccade occurs in the left eye. Thus, the eyes move conjugately under the control of a
single drive center.
7.
At the termination time, the cerebellar vermis, operating through the Purkinje cells,
inhibits the contralateral FN and stimulates the ipsilateral FN. Some of the stimulation of
the ipsilateral LLBN and IBN is lost because of the inhibition of the contralateral FN. The
ipsilateral FN stimulates the contralateral LLBN, EBN, and IBN. Further simulation of
the contralateral IBN occurs from the contralateral LLBN. The contralateral EBN then
stimulates the contralateral Abducens Nucleus. The contralateral IBN then inhibits the
ipsilateral EBN, TN, Abducens Nucleus, and contralateral Oculomotor Nucleus. With
this inhibition, the stimulus to the agonist muscles ceases. In most saccades, the SC
continues to fire even though the saccade has ended.
8.
The ipsilateral FN stimulation of the contralateral EBN allows for modest bursting in the
contralateral EBN (while still being inhibited by the ipsilateral IBN whose activity has
been reduced). This then stimulates the contralateral Abducens Nucleus and ipsilateral
Oculomotor Nucleus. With the stimulation from the contralateral EBN through the
contralateral Abducens Nucleus and ipsilateral Oculomotor Nucleus, the antagonist
muscles fire, causing the antagonist muscles to contract. Once the SC ceases firing, the
stimulus to the LLBN stops, allowing the resumption of OPN firing that inhibits the
ipsilateral and contralateral MLBN and the saccade ends.
13.10 SYSTEM IDENTIFICATION
In traditional applications of electrical, mechanical, and chemical engineering, the main
application of modeling is as a design tool to allow the efficient study of the effects of para-
metric variation on system performance as a means of cost containment. In modeling phys-
iological systems, the goal is not to design a system but to identify the parameters and
structure of the system. Ideally, the input and the output of the physiological system are
known, and some information about the internal dynamics of the system is available
(Figure 13.59). In many cases, either the input or output is not measurable or observable
but is estimated from a remote signal, and no information about the system is known.
System identification is the process of creating a model of a system and estimating the
Unknown
Biological
System
Input
Output
FIGURE 13.59
Block diagram of a typical physiological system without feedback.
