The status of an effort to define the directions needed to take in extending pilot models is reported. These models are needed to perform closed-loop (man-in-the-loop) feedback flight control system designs and to develop cockpit display requirements. The approach taken is to develop a hypothetical working model of the human nervous system by reviewing the current literature in neurology and psychology and to develop a computer model of this hypothetical working model

Lawrence, J. A.

English

NASA Technical Reports Server

, ] 82-1369 2 I"i
FUNCTIONAL STRUCTURE AND DYNAMICS OF THE
HUMAN NERVOUS SYSTEM
by: Joseph A Lawrence
This report is an interim report on the status of an effort to define
the directions we need to take in extending pilot models. We need these
models to perform closed-loop (man-ln-the-loop) feedback flight control
system designs and to develop cockpit display requirements. The approach
we have taken is to first develop a hypothetlcal working model of the human
nervous system by reviewing the current literature in neurology and psychology
and second to develop a computer model of this hypothetical workln& model.
One way of analyzing the nervous system, is to relate the neurons as to
their sensory input (Afferent system), processing (Association areas) and
(Efferent system) functions. Konorski, 1965, uses this approach ioutput
to arrive at some general characterietlcs of these functional systems.
Konorskl organizes the sensory pathways into seven basic functlonal
areas which he calls analyzers: the Visual, Acoustic, Kinesthetic, Somss-
thetlc and Gustatory, Vestibular, Emotional and Olfactory analyzers. These
analyzers are so grouped because of similarity in structure and function.
The analyzers have many characteristics in common. Each is built as
an n level structure, with each level being an aggregate of neurons per-
forming some siena1 processing and association tasks. Each level contains
cells, "units", that respond maximally to a particular "meaningful" stimulus
in the environment. Konorskl calls the response a "unitary Iv_ge response",
assuming the nervous system has integrated lower level parts into this
meaningful whole. In this manner, the nervous system can operate, for example,
from th_ "ti_h level on this unitary perception, and/or the unitary perceptlo
at this level can act as one piece of a more comprehensive unitary image at
the next level. This view is supported by the fact that some outputs from
this level proceed to the next higher level while others called "exit" neurons
leave the anatyzer to subserve lower level reflex loops. The unitary images
of higher levels tend to be more complex and refined relative to the level ""
of detail of the iw, ge.
Exit neurons proceed into areas we will call association areas. In these
areas unitary perceptions between analyzers are associated with one another
and with u:snlngful other perceptions formed over time by logic, thought
and concept for_Ing transformations. In these areas, internal models of
re•llty are formed which can be thought of as aggregates of expectation on
how present sensory inputs will transform as the result of tesper•l and
spsclal movements. Perceptions and models are operated on by logic oper-
ation at the higher levels, forming more abstract models, princxples and
rules etc. Basic drives are assoclsted with remembered past outcomew of
pstterns of movement to form goals or patterns of planned activity matched
to expected outcome. Often repeated patterns of thought or behavior become
prolrsmld a_t many levels as scheme and subeches,,. The models, goals and
scheme thus become • multi-level hierarchical set. This arrangement is
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consistent with philogenetlc and ontogenetlc theories of nervous system develop-
ment and function.
The third area by type of slgnal flow iv the efferent system or output
signal generating system. I will limit my co---pnts to those efferents
pertaining to body movement control. Although still somewhat controversial,
,;any believe that output activity is initiated by the formation of an image
of expected and desired movement. The image, however, must be accompanied
by a desire to move or we experience only the imap. The image is the vehicle
through which the nervous system ts configured for the action. One way for this
to occur naturally is for the efferent systems to use the multi-leveled unitary
i,_ages already created in the Kinesthetic and Somesthetic analyzers. The
many exit neuron_ at each level of the analyzers can subserve this function.
What we therefore have as a final output signal is many signals that are
somewhat integrated but with the final integration taking place in the spinal
coltua_ in the areas surrounding the particular motor neurons that drive the
(associated) mu3cles.
There are four additional aspects of the nervous system that are in_ortant
to a modeling process. One is the term consciousness. Defining conciousness
gets us into the whole Kind-Body issue (Spiritual - Physical). I will not
try to solve this problem here. But I think we all have the experience of
being _are of what we are doing in different ways. Sometimes we can be con-
centrating on performing a task and are aware of minute details of our goal,
our actions and the result of our actions. At o_her times we are almost
observers of our activity especially in well learned tasks. Finally, there
are sometimes when we realize that we've driven home almost automatically
while our cons:ions attention was focused on a work or social problem or
event. My point is that some tasks are performed with conscious awareness
and/or control while others, or parts of some tasks, are performed auto-
mati cally.
Observing epileptic patients lead Dr. Penfield (1975), a noted neuro-
surgeon responsible for mapping the functions of a large part of the human
cortex, to propose that there are two somewhat independent integrating
systems in the human nervous system. One he calls the '_dtghest Brain Mech-
anism" (HEM), which, he contends, supports the process of consciousness. The
other he calls the "Autoemtic Sensory-Motor Mechanism", (AS_q), and clail
that this mechanism can carry out very coeq)lex learned behavior patterns
even after the HEN has been i_mobilized by a pe_tt-,ssl epileptic seizure.
k_ether we accept Dr. Penfleld's proposed concept or our own cbservation of
our behavior, we must deal with the Job of allocating task assignment to
conscious awareness and control,automatic control with consciou_ awareness
or totally auto,_,ttc control and awareness, gut here we _mst deal with an
additional variable.
Consciousness tend_ to be serial In nature. The automatic system,
however, is structured as s hierarchical multi-leveled control system with
feedback and feedforvard loops and speclal function generators. The auto-
asttc system can and does perform many functions in parallel.
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How then can we properly allocate attention to tasks as we study workload?
I don't have the answer to this question yet, but it does allow me co appre-
ciate the confusion that presently exists in workload studies. Nultl-task
modeling efforts wit1 have to deal with finding a _ rkable solution.
The final elemont is the general state of a, _usal that the nervouG system
is in. The nervous system generates a bias si8"Al on the n_urons which con-
ditlons them for firing. Many factors affect the arousal level. When at low
levels, the neurons can't fire irlth normal signal Impute from processing units.
With high levels, the cells fire easily and the nervous system loses its ¢_it-
ICy to differentiate between slgnals, thus causing confusion and errors. This
factor is important enough to be In,'.luded in modeling considerations,
In summary then, we can view the nervous system as s multi-level hlerar-
chlcal automatic control system with par_11el processing, feedback and feed-
forward loops and wlth the potential of our being consclously aware of its
activity and to have consclo'_ control of many functions. Consciousness "
can be viewed as a _--ter controller acting through the control of the flow
of the complex imagery which drives the automatic system.
Reality consists of internal models, remembered transfor_ of perception,
which give a person a sense of understanding himself and his environment, and
the ability to establish a set of *"expect#._ons on what is going to happen next.
Indeed, we tend to operate continuously from this set of expectatlon_ and are
surprised when something different happens. Thls set of expectations gives
us the feedforvard capabilities that we use to plan actions to acco_llsh
goals, instantaneous or future. The particular set of expectations available
st any moment depends on the motlvatlonal state of the nervous system, a very
dynamic and difficult varlsble to consciously control - as any person attemptln&
meditation has already discovered.
A key point to understand is that the set of expectatior.a in the form of
images, act to configure the total nervous system as an op,;ratlng system -
both input and output. Because of sensory filtering, ou_ expectations de-
terndne to :_ large degree whst we perceive.
Because of the autoutlc parallel processing, it is possible for several
tasks to be performed slmultaneously as lo_s as sensory, processing and
output elements are not in conflict in perfo,_mlng these functions. In this
way, for example, we can maintain our sense of orientation (mode+l) even
though we are focused o, giviL, g concentrated effort to identifying a
target.
With all these variables and this complexity, the multl-task pilot model
wlU have to also be complex and larse. Knowing the structure and functions
of the nervous system will allow us to nkp intellegent dec.tsions on how to
ltmit the model, set up experiment_ and amalyse the rasults.
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REFERENCES
Asanuma, H., et ai.(1979) Integration inth___eNervpus _. Tokyo: Igaku-Shoin.
Bandler, R. and Grinder, J. (1975) Th___eStructureof Magic, Vol. i. California:
Science and Behavior Books.
Griffin, D.R. (1976) Th__eQuestion of Animal Awareness: Evolmtionar_ Continuity of
Mental Experience. New York: Rockefeller University Press.
James, W. (1918) The Principles of Psychology. New York: Henry Holt and Company.
Jerison, H.J. (1973) Evolution of the Brain and Intelligence. New York: Academic
Press.
Konorski, J. (1970) Integrative Activit Z of the Brain: An Interdisciplinary
Approach. Chicago and London: The University of Chicag---oPress.
0akley, D.A. (1979) Cerebral cortex and adaptive behavior. IN Oakley, D.A. and
Plotkin, H.C. (1979) Brain, Behaviour and Evolution. New York: Methuen.
#
Penfield, W. (1975) Th___eMYsteryof the Mind: A Critical Stu__d_ofConsciousness
and the Human Brain. New Jersey: Princeton University Press.
Sommerhoff, G. (1974) Logic of the Living Brain. New York: John Wiley and Sons.
Sperry, R.W. (197o) Consciousness, freewill and personal identity. IN Oakley,
D.A. and Plotkin, H.C. (1979) Brai_____n,Behaviour and Evolution. New York:
Methuen.
Yho, C.H. (1979) The anatomy of the vertebrate nervous system: an evolutionary
and developmental porspective. IN Oakley, D.A. and Plotkin, H.C. (1979) Brai____n,
Behaviour and Evolution. New York: Methuen.
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Functional structure and dynamics of the human nervous system

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