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ELEC”ROPHYSIOL0GICAL
THEORY
49
interconnected
with
strong
transcortical fibers,
so
that they tend to act
unitarily, and some spillover of effects
is
suggested in the literature.
The thalamic radiation reaches them
in
the fibers from donomedial
nucleus
to
frontal cortex, from anteromedial nucleus
to
the cingulate
region, and (probably) from the suprageniculate nucleus
to
anterior
temporal cortex. Their projective activity
into
the central activating
system appears
to
parallel that from
secondary
sensory areas such as
the parastriate. Upon what data do they act? There
is
evidence that they
may receive sensory data, presumably through transthalamic or intra-
thalamic channels, only after i t has been cortically elaborated in primary
specific-sensorypathways. Using toposcopic analysis, Walter (1954) has
demonstrated a time lag between occipital and temporal cortex
in
re-
sponses to patterned visual stimulation which seems to be consistent
with such an interpretation of cephalic events.
On
the basis of record-
ings taken a t the vertex from the cingular
gyrus,
Gastaut (1954) hy-
pothesized that messages arriving in
sensory
areas may be accompanied
by a “duplicate” for the cingular region, a “secondary message which
carries the affective charge of the information,” and that the anterior
cingulate
gyrus
is
thus a “region of convergence for all sensory routes.”
Penfield’s observations of the temporal lobe (1952b) seem
to
indicate a
similar convergence of modalities in that region.
The
diversity of the responses elicited from the anterior cingulate
region is best explained
on
the hypothesis of a topographical localization
of affects.
A
similar topographical representation
in
frontal regions is
suggested by the indication of point-to-point projection from dorso-
medial nucleus
to
frontal cortex reported by Jasper (1949, p.
406).
The
establishment by experiment of the existence of such
a
topographical
organization in thalamus and cortex would resolve the anomaly under
which the donomedial and anteromedial nuclei of the thalamus are clas-
sified as “specific” nuclei. A topographical representation of intents, af-
fects, and sequential memories
is
of c ome difficult to conceive imagina-
tively, but
it
should not be rejected for that reason.
Interference mechanims.
The central problem of a complete theory
of hypnosis will be
to
identify the mechanisms of interference. Inhibi-
tion could conceivably be effected by the action
of
the corticoreticular
projections: through attenuating the diffuse projection; through abolish-
ing recruiting responses at the cortex;
or
through interfering with the
thalamic repetitive discharge
in
specific-sensory volleys. Interaction
between the specific projection and the central reticular formation could
possibly be inhibited a t the superficiea of specific-sensory and somes-
thetic cortex by a simple blocking of the somatodendritic conduction of
specific impulses synapsing
at
layer 4 onto the somata of lona-axon
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