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 Previous Article
The Journal of Neuroscience, June 1, 1998, 18(11):4417-4423
Perceptual Correlates of Changes in Cortical Representation of
Fingers in Blind Multifinger Braille Readers
Annette
Sterr1,
Matthias M.
Müller1,
Thomas
Elbert1,
Brigitte
Rockstroh1,
Christo
Pantev2, and
Edward
Taub3
1 Department of Psychology, University of Konstanz,
Fach D25, D-78457 Konstanz, Germany, 2 Institute of
Experimental Audiology, University of Münster, D-48129
Münster, Germany, and 3 Department of Psychology,
University of Alabama at Birmingham, Birmingham, Alabama 35294
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ABSTRACT |
The mature mammalian nervous system alters its functional
organization in a use-dependent manner. Enhanced stimulation of a body
part enlarges its cortical representational zones and may change its
topographic order. Little is known about the perceptual and behavioral
relevance of these plastic alterations in cortical organization. We
used blind Braille readers who use several fingers on each hand and who
do so for many hours each day as a model to investigate this issue.
Magnetic source imaging indicated that the cortical somatosensory
representation of the fingers was frequently topographically disordered
in these subjects; in addition, they frequently misperceived which of
these fingers was being touched by a light tactile stimulus. In
contrast, neither the disordered representation nor mislocalizations
were observed in sighted controls. Blind non-teacher Braille readers
who used only one finger for reading were not significantly different
from the sighted controls. Thus, use-dependent cortical reorganization
can be associated with functionally relevant changes in the perceptual
and behavioral capacities of the individual.
Key words:
blindness; Braille reading; cortical reorganization; somatosensory; sensory deafferentation; tactile perception; cortex; organization; Semmes-Weinstein monofilaments
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INTRODUCTION |
In the somatosensory system,
cortical reorganization occurs after both increased sensory input to a
portion of the brain (Jenkins et al., 1990 ; Recanzone et al.,
1992a,-c) and decreased sensory input produced by either
deafferentation (Pons et al., 1991) or amputation (Merzenich et al.,
1984; Yang et al., 1994; Elbert et al., 1994; Flor et al., 1995).
Decreased input has been shown to be correlated with outcomes of
functional relevance to the experience of an individual. Thus, after
upper extremity amputation or deafferentation, the portion of the brain
representing the now absent body part is "taken over" by adjacent
cortical regions representing portions of the body with intact input
(Pons et al., 1991; Elbert et al., 1994; Florence and Kaas, 1995). Flor
et al. (1995) found that the amount of this cortical reorganization was highly correlated with phantom limb pain. This result has been replicated in a number of subsequent studies using MEG, EEG, and magnetic resonance imaging (Knecht et al., 1996; Birbaumer et al.,
1997). In the auditory system, the amount of cortical reorganization has been found to have a strong relationship to tinnitus
(Mühlnickel et al., 1998). In addition, the increased use of the
digits occurring in musical practice has been found to be associated
with focal dystonia in professional musicians (Elbert et al.,
1996).
Use-dependent expansion of cortical somatosensory representation in
area 3b is correlated, of course, with the increase in the sensory
stimulation that produced it, but this increased cortical representation has not been shown to be otherwise correlated with additional functionally relevant changes in the perceptual or behavioral capacities of humans, as opposed to the case of
input-decrease cortical reorganization after amputation. There is
suggestive evidence that this is the case (Elbert et al., 1995, 1997;
Rockstroh et al., 1998), but there has not yet been a direct
demonstration.
The extent of somatosensory cortical representation of the digits has
been demonstrated to be dependent on the amount and type of sensory
input arriving in the primary somatosensory cortex. Elbert and
coworkers (1995), pursuing in humans the seminal work of Jenkins,
Merzenich, and Recanzone and their associates carried out with new
world monkeys (Jenkins et al., 1990; Recanzone et al., 1990, 1992a-c),
used magnetic source imaging to show that the somatosensory cortical
representation of the left hand of string players, which engages in the
complex and demanding task of fingering the strings, is significantly
expanded. Pascual-Leone and co-workers (1993), examining a related
issue, used transcranial magnetic stimulation to demonstrate in blind
Braille readers that the motor representation of the reading finger is
expanded. A number of studies have been carried out concerning the
factors determining the discreteness of the topographic representation of the fingers in the homuncular map of the somatosensory cortex. The
surgical joining of two digits in owl monkeys was found several months
later to have resulted in the fusion of the cortical representation of
the syndactylous digits (Clark et al., 1988; Allard et al., 1991),
whereas the opposite intervention, surgical separation of syndactylous
digits, was found to lead to a corresponding separation of the
somatosensory cortical representation of the digits in humans (Mogilner
et al., 1993). The hypothesis that the fusion of cortical
representations was caused by the increase in simultaneity of
somatosensory inputs when digits are joined (Clark et al., 1988; Allard
et al., 1991) received support from two experiments with owl monkeys
from the same laboratory showing that (1) prolonged simultaneous
stimulation of three fingers led to the development of cortical
neuronal receptive fields spanning all three digits, a phenomenon not
observed to occur in control animals (Wang et al., 1995), and (2)
sustained, repetitive gripping under conditions of high force and
vibration led to "digit representations (that) were geographically
disorganized" (Byl et al., 1996, 1997).
On the basis of the hypothesis that the fusion of cortical
representations is caused by increased simultaneity of sensory inputs,
we tested the somatotopic representations of blind Braille readers who
(1) used three fingers (digits 2, 3, 4) simultaneously for reading and,
(2) as instructors of the method, typically engaged in this practice
several hours daily. We also tested blind Braille readers who use one
finger and sighted non-Braille reading subjects. The cited literature
suggests that three-finger reading should lead to both an expansion of
the cortical representation of these fingers and an alteration in their
topographic arrangement. If this is the case, one may ask whether such
cortical reorganizational changes might in turn be correlated with
significant perceptual changes, and if so would the cortical and
perceptual alterations bear a meaningful relationship to one
another?
A brief account of these results has been published previously (Sterr
et al., 1998).
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MATERIALS AND METHODS |
Stimuli. Stimulation consisted of light superficial
pressure applied by means of a pneumatic stimulator using a standard, nonpainful stimulation intensity (for more details, see Elbert et al.,
1994). Tactile stimulation was delivered to the midvolar aspect of the
distal phalanx of left and right D1, D2, D5, and right and left corners
of the lower lip (LL). At each site, 512 stimuli were delivered at a
rate of 3.3/sec. Stimulation site sequence was varied according to a
fixed irregular order across subjects.
Subjects. All subjects were right-hand dominant. Four blind
three-finger Braille readers (35 ± 10 years), six blind
one-finger Braille readers (48 ± 8 years), and five sighted
non-Braille-reading persons (35 ± 7 years) participated in the
study. The three-finger Braille readers worked as Braille instructors,
using Braille daily for 2-6 hours. For reading they used both index
fingers (D2) to decode the dot pattern, the middle fingers (D3) to
detect the spaces between the distinct Braille signs, and the fourth
fingers (D4) to keep track of the line. The blind subjects had lost
sight because of diseases affecting the peripheral components of the visual system and were selected for not having any further neurological problems. Light perception was present in two cases; the remainder of
the subjects had no residual vision. Three of the three-finger readers
had lost vision at birth because of retinal disease and had studied
Braille in school beginning at age 5 years. One three-finger reader
became blind at age 16 years as a result of optic nerve atrophy; she
had used Braille for 10 years at the time of recording. Four of the
one-finger readers used one index finger for reading (three right D2,
one left D2), and two readers used both index fingers. Three of these
readers were congenitally blind and read Braille since age 6 years. Two
one-finger readers suffered from visual impairment attributable to
progressive retinal disease and became entirely blind at age 20 and 23 years, whereas a sixth subject became blind as a result of optic nerve
transection at age 30 years. At the time of the experiment the latter
subjects had been reading Braille for 25, 35, and 16 years,
respectively. All five sighted subjects were members of the university
staff. The protocol was approved by the institution's review board,
and subjects gave informed consent after hearing a description of the
study.
Recordings. Magnetic fields were recorded in a magnetically
shielded room using a 37-channel magnetometer (Magnes, BTi, San Diego,
CA) with a sampling rate of 297.6 Hz. The sensor array was positioned
over the hemisphere contralateral to the side of stimulation (centered
at C3 or C4) and evoked magnetic fields were obtained by on-line
averaging.
Sensory testing. After the MEG recording, the sensory
thresholds of the fingertips were determined using a von Frey-type
aesthesiometer (Semmes-Weinstein-Monofilaments, model #16010, Lafayette
Instruments Company). Participants were instructed to indicate verbally
when the touch was felt. Stimulation consisted of pressing a von Frey hair gently against the skin until it just began to bend. A stimulus of
a given strength was applied to the midvolar surface of the distal
phalanx of each of the digits of one of the hands in random order;
sighted subjects were required to keep eyes closed. Each hand was
tested separately; thresholds for each finger were determined twice by
the method of limits, using stimulus series of increasing and
decreasing strengths. Counterbalancing was used for direction of
stimulus series both within and between subjects and for order of the
hand that was tested first. Ten to 15 min after threshold determination, the ability to correctly identify which finger was being
touched was determined, starting with the originally tested hand. The
threshold von Frey hair stimulus for each subject (von Frey hair
strengths: 2.44-2.83) was applied to each digit five times in a fixed
irregular order with an interstimulus interval of 1-2 sec. The same
hand was then tested in the same fashion at one von Frey hair strength
subthreshold and at one or more steps above threshold until the digital
location of stimulation was correctly identified on each trial. The
same testing procedure was then carried out for the opposite hand. For
tabulation purposes, a hand was characterized as exhibiting
mislocalization if incorrect localization occurred for at least one
finger on at least two out of five trials at the threshold stimulation
value.
Data analysis. The averaged evoked magnetic field data were
digitally filtered using a second order bandpass filter (3-30 Hz).
Within the range of 30-70 msec after stimulus onset, a first major
peak was identified in each of the evoked waveforms. For each evoked
magnetic field, a single equivalent current dipole (ECD) model (best
individually fitting local sphere) was fitted, and the medians of the
dipole moment and the dipole location for the peak in the signal power
(root mean square across channels) were computed, if the following
requirements were met: (1) a signal-to-noise ratio >4, (2) a goodness
of fit of the ECD model to the measured field >0.95, and (3) a minimal
confidence volume of the ECD location <300 mm3. The
Euclidean distance and the distance in the three separate dimensions
were calculated between the centers of cortical responsivity to tactile
stimulation of each of the digits (D1-D2, D1-D5, and D2-D5) and of
each digit and the ipsilateral lower lip (D1-LL, D2-LL, and
D5-LL).
To obtain an estimate of the cortical topographic order/disorder of the
somatotopic organization, all topographic arrangements in which the
cortical representation of the digits was in the correct order in the
inferior-superior dimension (D1 D2D5) were assigned a value of
zero. If there was topographic disorder in any pair of cortical digital
representations (D1-D2, D2-D5, or D1-D5), each of the distances in
the deviant direction was summed and placed in the numerator of a
fraction whose denominator was the distance between representations of
the two fingers most distant from one another. Using the size of the
cortical representation of the hand as a denominator serves to correct
for the fact that there was an expansion of the hand representation in
the three-finger blind Braille readers; without this correction the
amount of cortical disorder would be overestimated for this group. The
measure can be calculated as follows:
For all dependent variables, ANOVAs or t tests
(two-tailed) were calculated. Post hoc comparisons were
conducted by Scheffé tests.
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RESULTS |
Evoked magnetic fields and dipole localizations
No obvious differences were observed between the wave forms
elicited in the three groups (Fig. 1).
For the first major peak, average latencies ranged between 52 and 54 msec for the different fingers, but were significantly shorter for the
lip (37 msec; F(3,27) = 17.0; p < 0.01). Average amplitudes were 53-81 fT; corresponding dipole
moments had an average strength of 10.3-13.9 nAm. There was no
difference in latencies or response amplitudes between the groups for
any of the stimulation locations (ANOVAs).
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Figure 1.
Set of individual waveforms indicating the
magnetically evoked responses for stimulation of the right index finger
of two members of each group: three-finger blind Braille readers,
one-finger blind Braille readers, and sighted controls.
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We observed a substantial difference in the size of the hand
representation between the groups (F(2,12) = 16.6; p < 0.001) (Fig.
2). The size of the hand representation
was measured as the distance between the representations of the digits
that were farthest apart in the inferior-superior dimension
(medial-lateral dimension on the surface of the cortex) (Fig.
2A). The hand representation for the three-finger
readers was greatly enlarged, measuring 14 mm compared with 8 mm in
one-finger readers and 7 mm for the sighted controls. The difference
between the three-finger readers and both the one-finger readers and
the sighted controls was significant (three-finger vs one-finger
readers: t = 4.4, p < 0.001;
three-finger readers vs controls: t = 6.0, p < 0.001), but the latter two groups were not
significantly different from one another.
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Figure 2.
Distance (cm) between the cortical representation
("center of gravity" determined as ECD-location) of the first (D1,
thumb) and fifth (D5, little finger) digits for three-finger blind
Braille readers, one-finger blind Braille readers, and sighted
controls. A, Distance in the inferior-superior dimension
(medial/lateral dimension on the surface of the cortex). B,
Euclidean distance.
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Similarly, the Euclidean distances in three-dimensional space between
the three digit locations were significantly greater in the
three-finger readers than in the controls
(F(1,7) = 13.1; p < 0.001) and
in the one-finger readers (F(1,8) = 8.7;
p < 0.05) (Fig. 2B). Finally, in all
four one-finger readers who used just one hand, there was a substantial
increase in the dipole strength of the reading D2 compared with the
nonreading D2 (18.7 ± 7.0 nAm vs 9.2 ± 1.6 nAm), suggesting
that there was an expansion of the reading D2 (Fig.
3). The laterality coefficient of the dipole strength Q of the reading D2 compared to the
non-reading D2
{(Qreading Qnonreading)/[(Qreading+Qnonreading)/2]}
was 0.63 (t = 3.7; p < 0.05). The
right-left difference in the dipole moment for the two D2s in sighted
subjects was not significant (laterality coefficient = 0.07). This
comparison was not relevant for the three-finger readers because they
all read with both hands, although there was a tendency to relay more
heavily on the leading right hand, which may be reflected in the
nonsignificant difference in the figure.
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Figure 3.
Dipole moment (nAm) for stimulation of the index
finger (D2) of the right hand of the three-finger blind Braille
readers, the reading hand of one-finger blind Braille readers (five
right, one left), and the right hand in sighted controls as well as the
left, nonreading D2s for the three groups.
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Cortical somatotopic organization
The analysis of the topographic order of the cortical
representation of the digits revealed a significant difference between the three groups (F(2,12) = 11.53;
p = 0.002). In each sighted subject, the expected
homuncular pattern was observed, with D1 being in the most inferior
(lateral) position, D2 being more medial, and D5 being in the most
superior (medial) position (Fig. 4). In
each of the three-finger Braille readers, this pattern of finger representation was changed in at least one of the hemispheres (Fig. 4).
The three-finger blind Braille readers differed significantly from the
one-finger readers in the amount of cortical digital topographic
disorder (post hoc Scheffé test,
p = 0.007) and from the sighted subjects
(p = 0.003). The one-finger readers and sighted subjects did not differ significantly from one another. In the one-finger Braille readers, the cortical topography of finger representations was disordered in only one of six subjects (Fig. 4),
and for the three-finger readers each subject exhibited topographic disorder in at least one hemisphere. For the three-finger readers the
disordered topography was in the left hemisphere for two subjects, the
right hemisphere for one subject, and both hemispheres for one subject.
Thus, five of eight possible hemispheres showed a disordered
topographic arrangement of the fingers. In three cases, the D1
representation was medial to one or both of the other two digits,
whereas in the other two cases, D2 and D5 were in reversed order.
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Figure 4.
Distance (cm) along the z-axis
(inferior-superior) between the centers of cortical responsivity for
right and left D1, D2, and D5 for each three-finger blind Braille
reader, one-finger blind Braille reader, and sighted control subject.
X indicates disorganization in the digital topographic
arrangement; M indicates tactile mislocalization. Each
histogram represents the data from a single subject, with the
topographic digital representation of the left and right hemispheres
shown separately. The black bar represents the distance
along the z-axis from the representation of D1 to that of
D5. The gray bar represents the distance from D2 to D5. The
two bars on the left are for the left hemisphere
and the two bars on the right are for the right
hemisphere. The data for the two one-finger readers who used the left
hand are presented in the first and second histograms of the
middle row.
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Sensory thresholds and digital mislocalization
The reading fingers of the blind Braille readers had lower tactile
thresholds than did the homologous fingers of the sighted subjects.
When all fingers were included in the analyses, blind persons tended to
have lower sensory thresholds than sighted controls (t = 2.0; p < 0.07). The ANOVA revealed a significant
GROUP × FINGER interaction (F(8,40) = 4.8;
p < 0.01) as well as a main effect FINGER
(F(4,40) = 8.8; p < 0.01) (Fig.
5), indicating that there were different
sensory thresholds for the respective fingers and that the extent of
this difference was not the same across the groups. Post hoc
comparisons between the fingers of the right hand of three-finger
readers and the sighted controls revealed a significantly lower
threshold for the digits of the three-finger readers: D2
(t = 3.01; p < 0.05), D4
(t = 2.7; p < 0.05) and D5
(t = 3.3; p < 0.05); the group
difference for D3 did not reach significance (t = 2.1; p < 0.08). One-finger readers exhibited lower
thresholds in digits D2 (t = 2.3; p < 0.05) and D3 (t = 2.5; p < 0.05) as
compared with the sighted controls.
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Figure 5.
Absolute tactile thresholds (in von Frey hair
strengths) for each of the digits of the three-finger blind Braille
readers, the one-finger blind Braille readers, and the sighted control
subjects.
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It was also found in each of the three-finger readers that there was a
strong tendency to mislocalize which finger was being touched during
tactile sensory threshold determination. There was no difficulty in
determining that one of the fingers had been touched, but there was a
problem in identifying which one it was. In contrast, none of the
sighted subjects and only one of the one-finger readers reported
difficulties in determining which of the fingers had been stimulated.
If mislocalization on either or both hands is counted as a one and the
absence of mislocalizations as a zero, Fisher's exact test
(two-tailed) indicates that there is a significant difference between
groups (p = 0.005, for the three groups;
p = 0.02, three-finger vs one-finger readers;
p = 0.008, three-finger readers vs sighted subjects;
one-finger readers vs sighted subjects, not significant).
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DISCUSSION |
The aim of the present study was to investigate the
somatotopic representation of the fingers of blind three-finger Braille readers. In addition, subjects underwent a test in which they had to
identify tactile stimuli slightly above individual sensory thresholds
to investigate possible perceptual changes. The finding of greatest
interest in this study is that the cortical somatosensory representation of the fingers in three-finger Braille readers was often
topographically disordered. Another possibility is that the digital
representations of the three-finger readers exhibit poor somatotopy, a
smearing of the cortical representations, rather than a disorder in the
topographic sequencing. Both possibilities are similar, however, in
that they represent a departure from normal somatotopy. This could be
attributable to the simultaneity of tactile input to the three reading
fingers during Braille reading as opposed to the frequently temporally
noncoincident tactile stimulation of the fingers (i.e., with a
separation of >20 msec (Allard et al., 1991; Wang et al., 1995). The
hands for which cortical topographic disarrangement of digital
representation occurred also showed a surprising tendency in every case
to misperceive which finger was being touched by a light tactile
stimulus. The cross-sectional nature of this study does not permit a
conclusive determination of causal relationships, but the data are
strongly suggestive. Tactile mislocalization clearly has a maladaptive aspect. However, it is interesting to note that for three-finger Braille reading, as for visual reading, it is advantageous to take in a
substantial amount of information all at once. It would be more
efficient not to have to discriminate separately the nature of the
information coming in over the different reading fingers, but for the
information to be melded together so that it could be processed as a
whole. In this way the "smearing" of the digital cortical
representations in three-finger Braille readers would be adaptive. This
interpretation receives support from the fact that one-finger Braille
reading, which does not require the simultaneous processing of
information from different fingers, produces a much lower incidence of
such smearing. Thus, it is possible that the smearing in the
three-finger readers has a purposive element. Because this process
could have value for the individual, learning might enter to elaborate
and shape it so that it is most useful for the individual. Another
possibility is that the topographic smearing was actually an
adventitious effect, whatever the advantageous consequence it had for
the efficiency of Braille reading.
It might be noted that the three-finger blind Braille readers read with
both hands. The topographic disorder or poor somatotopy and tactile
mislocalization occurred for both hemispheres and hands for one
subject, but for only one hemisphere and hand for the other three. The
reason for the absence of the disorder phenomenon in one hemisphere and
mislocalization in the corresponding hand for these three subjects
could have to do with such individual differences during Braille
reading as amount of force exerted with the digits of the two hands,
bimanual difference in amount of isometric tension, differences in
postural adjustments of the two arms and hands, differences in the
attention paid to the information coming from the two hands, etcetera;
there might also be differences in the structural or functional
organization of the two hemispheres that could account for the observed
differences. The important consideration, though, is that when there
was hemispheric digital topographic disorder, there was also tactile
mislocalization in the contralateral hand.
One of the three-finger Braille readers became blind and learned
Braille reading when an adult. This was also the case for two of the
one-finger blind Braille readers, whereas a third, who became blind
when 7 years of age, did not learn Braille reading until he was 20. Therefore, the data indicate that both the alteration in cortical
topography and the enlargement of cortical digital representations can
occur in adulthood; they do not take place only when the nervous system
is immature.
This study also indicates that the somatosensory representation of the
fingers in three-finger blind Braille readers is enlarged. This
confirms the previous observation in animals (Recanzone et al.,
1992a-c), in sighted Braille readers (Rockstroh et al., 1998), and for
the left hand in string players (Elbert et al., 1995) that the cortical
somatosensory representation of the hand (and presumably other portions
of the body) is plastic and responds to increases in use of that body
part with an expansion in size. It also confirms the observation that
the motor representation of a reading finger in blind Braille readers
can be enlarged (Pascual-Leone et al., 1993). The enlarged finger
representation is clearly the result of the increase in behaviorally
relevant sensory input during Braille reading. It is possible that this
enlargement in turn aids in the appreciation of the Braille letters,
although data are not currently available to determine whether this is the case.
A more general question concerns the role of cortical reorganization in
the functional economy of the organism. After upper extremity
amputation, phantom limb pain has been shown to have a very strong
relationship to cortical reorganization (Flor et al., 1995). Tinnitus,
which may also be caused by neurological injury, is similarly strongly
correlated with cortical reorganization (Mühlnickel et al.,
1998), as are chronic lower back pain (Flor et al., 1997) and focal
dystonia (Elbert et al., 1996). Each of these conditions is highly
aversive. In the present paper, it has been shown that changes in
cortical representation resulting from increases in peripheral input
can be associated with a nonadaptive phenomenon (i.e., digital tactile
mislocalization), but it is also possible that the "smearing" of
the topographic arrangement of the digital cortical representation in
blind Braille readers is associated with an adaptive phenomenon as well
(i.e., a fusion in the incoming digital information), which would make
reading more efficient. A significant issue that remains to be resolved by future research is whether cortical reorganization after
neurological injury can be related to positive outcomes as well as to
the aversive conditions noted above. The candidate process that is
potentially of greatest importance is the recovery of function after
damage to the nervous system.
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FOOTNOTES |
Received Dec. 29, 1997; revised March 2, 1998; accepted March 25, 1998.
This work was supported by Biomagnetic Technologies Inc., a grant from
the Deutsche Forschungsgemeinschaft to T.E., and a grant from the
Rehabilitation Research Service of the Veterans Administration
(B95-975R) to E.T.
Part of this work was carried out at the Scripps Clinic and Research
Foundation, La Jolla, CA.
We are grateful to the staff members of the San Diego Center for the
Blind and the Braille Institute La Jolla for referring participants. We
thank Patti Quint, Lacey Kurelowech, and Joslyne Foley for technical
assistance.
Correspondence should be addressed to A. Sterr, University of Konstanz,
Department of Psychology, 78457 Konstanz, Germany.
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REFERENCES |
-
Allard T,
Clark SA,
Jenkins WM,
Merzenich MM
(1991)
Reorganization of somatosensory area 3b representations in adult owl monkeys after digital syndactyly.
J Neurophysiol
66:1048-1058[Abstract/Free Full Text].
-
Birbaumer N,
Lutzenberger W,
Monotya P,
Larbig W,
Unertl K,
Töpfner S,
Grodd W,
Taub E,
Flor H
(1997)
Effects of regional anesthesia on phantom limb pain are mirrored in changes in cortical reorganization.
J Neurosci
17:5503-5508[Abstract/Free Full Text].
-
Byl NN,
Merzenich MM,
Jenkins WM
(1996)
A primate genesis model of focal dystonia and repetitive strain injury: I. Learning-induced dedifferentiation of the representation of the hand in the primary somatosensory cortex in adult monkeys.
Neurology
47:508-520[Abstract/Free Full Text].
-
Byl NN,
Merzenich MM,
Cheung S,
Bodenbaugh P,
Nagarajan SS,
Jenkins WM
(1997)
A primate model for studying focal dystonia and repetitive strain injury: effects on the primary somatosensory cortex.
Phys Ther
77:269-284[Abstract/Free Full Text].
-
Clark SA,
Allard T,
Jenkins WM,
Merzenich MM
(1988)
Receptive fields in the body-surface map in adult cortex defined by temporally correlated inputs.
Nature
332:444-445[Medline].
-
Elbert T,
Flor H,
Birbaumer N,
Knecht S,
Hampson S,
Larbig W,
Taub E
(1994)
Extensive reorganization of the somatosensory cortex in adult humans after nervous system injury.
NeuroReport
5:2593-2597[Web of Science][Medline].
-
Elbert T,
Pantev C,
Wienbruch C,
Hoke M,
Rockstroh B,
Taub E
(1995)
Increased use of the left hand in string players associated with increased cortical representation of the fingers.
Science
220:21-23.
-
Elbert T, Sterr A, Candia C, Rockstroh B, Taub E
(1996) Representational cortical plasticity as revealed by
magnetic source imaging: how the brain learns to play the violin. First
Berlin Workshop On Cortical Plasticity, Berlin, November.
-
Elbert T,
Sterr A,
Flor H,
Rockstroh B,
Knecht S,
Pantev C,
Wienbruch C,
Taub E
(1997)
Input-increase and input-decrease types of cortical reorganization after upper limb extremity amputation in humans.
Exp Brain Res
117:161-164[Web of Science][Medline].
-
Flor H,
Elbert T,
Knecht S,
Wienbruch C,
Pantev C,
Birbaumer N,
Larbig W,
Taub E
(1995)
Phantom-limb pain as a perceptual correlate of cortical reorganization following arm amputation.
Nature
375:482-484[Medline].
-
Flor H,
Braun C,
Elbert T,
Birbaumer N
(1997)
Extensive reorganization of primary somatosensory cortex in chronic back pain.
Neurosci Lett
224:5-8[Web of Science][Medline].
-
Florence SL,
Kaas JH
(1995)
Large-scale reorganization at multiple levels of the somatosensory pathway follows therapeutic amputation of the hand in monkeys.
J Neurosci
15:8083-8095[Abstract].
-
Jenkins WM,
Merzenich MM,
Ochs MT,
Allard T,
Guic-Robles E
(1990)
Functional reorganization of primary somatosensory cortex in adult owl monkeys after behaviorally controlled tactile stimulation.
J Neurophysiol
63:82-104[Abstract/Free Full Text].
-
Knecht S,
Henningsen H,
Elbert T,
Flor H,
Hoehling C,
Pantev C,
Taub E
(1996)
Reorganizational and perceptual changes after amputation.
Brain
119:1213-1219[Abstract/Free Full Text].
-
Merzenich MM,
Nelson RJ,
Stryker MP,
Cynader MS,
Schoppmann A,
Zook JM
(1984)
Somatosensory cortical map changes following digit amputation in adult monkeys.
J Comp Neurol
224:591-605[Web of Science][Medline].
-
Mogilner A,
Grossman JAI,
Ribary U,
Joliot M,
Volkmann J,
Rapaport D,
Beasley RW,
Llinas RR
(1993)
Somatosensory cortical plasticity in adult humans revealed by magnetoencephalograhy.
Proc Natl Acad Sci USA
90:3593-3597[Abstract/Free Full Text].
-
Mühlnickel W,
Elbert T,
Taub E,
Flor H
(1998)
Deviations from the tonotopic map are correlated with tinnitus strength.
In: Advances in biomagnetism research: Biomag96, Vol II Aine C, Okada Y, Stroink G, Swithenby S, Wood C, (eds). New York: Springer-Verlag.
-
Pascual-Leone A,
Cammarota A,
Wassermann EM,
Brasil-Neto JP,
Cohen LG,
Hallett M
(1993)
Modulation of motor cortical outputs to the reading hand of Braille readers.
Ann Neurol
34:33-37[Web of Science][Medline].
-
Pons TP,
Garraghty PE,
Ommaya AK,
Kaas JH,
Taub E,
Mishkin M
(1991)
Massive cortical reorganisation after sensory deafferentation in adult macaques.
Science
252:1857-1860[Abstract/Free Full Text].
-
Recanzone G,
Allard TT,
Jenkins WM,
Merzenich MM
(1990)
Receptive-field changes induced by peripheral nerve stimulation in SI of adult rats.
J Neurophysiol
63:1213-1225[Abstract/Free Full Text].
-
Recanzone GH,
Jenkins WM,
Hradek GT,
Merzenich MM
(1992a)
Progressive improvement in discriminative abilities in adult owl monkeys performing a tactile discrimination task.
J Neurophysiol
67:1015-1030[Abstract/Free Full Text].
-
Recanzone GH,
Merzenich MM,
Jenkins WM
(1992b)
Frequency discrimination training engaging a restricted skin surface results in an emergence of a cutaneous response zone in cortical area 3a.
J Neurophysiol
67:1057-1070[Abstract/Free Full Text].
-
Recanzone GH,
Merzenich MM,
Jenkins WM,
Grajski KA,
Dinse HR
(1992c)
Topographic reorganization of the hand representation in cortical area 3b of owl monkeys trained in a frequency-discrimination task.
J Neurophysiol
67:1031-1056[Abstract/Free Full Text].
-
Rockstroh B,
Vanni S,
Elbert T,
Hari R
(1998)
Extensive somatosensory stimulation alters somatosensory evoked fields.
In: Advances in biomagnetism research: Biomag96 International Conference on Biomagnetism. Aine C, Okada Y, Stroink G, Swithenby S, Wood C, (eds). New York: Springer-Verlag.
-
Sterr A,
Müller MM,
Elbert T,
Rockstroh B,
Pantev C,
Taub E
(1998)
Changed perception in Braille-readers.
Nature
1998:134-135.
-
Wang X,
Merzenich MM,
Sameshima K,
Jenkins WM
(1995)
Remodelling of hand representation in adult cortex determined by timing of tactile stimulation.
Nature
378:71-75[Medline].
-
Yang TT,
Gallen CC,
Ramachandran VS,
Cobb S,
Schwartz BJ,
Blum FB
(1994)
Noninvasive detection of cerebral plasticity in adult human somatosensory cortex.
NeuroReport
5:701-704[Web of Science][Medline].
Copyright © 1998 Society for Neuroscience 0270-6474/98/18114417-07$05.00/0
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|
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|
|
|
|
|
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|
|
|
|
|
|
|
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|
|
|
|
|
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|
|
|
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|
|
|
|
|
|
|
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|
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Top
Abstract
Introduction
![<UP>= </UP><FR><NU><AR><R><C>[<UP>deviance</UP>(<UP>D1−D2</UP>)]<UP>+</UP>[<UP>deviance</UP>(<UP>D1−D5</UP>)]</C></R><R><C><UP>+</UP>[<UP>deviance</UP>(<UP>D2−D5</UP>)]</C></R></AR></NU><DE><UP>distance between farthest apart finger representations</UP></DE></FR><UP> .</UP>](/content/vol18/issue11/fulltext/4417/img002.gif)
