Neuropsychologia, 196~, Vol. 6, pp. 255 to 265. Pergamon Press. Printed in England
ACQUISITION OF MOTOR SKILL AFTER BILATERAL
MEDIAL TEMPORAL-LOBE EXCISION
SUZANNE CORKIN
Department of Psychology,MassachusettsInstitute of Technology,Cambridge,
Massachusetts 02139, U.S.A.
(Received 5 April 1968)
Abstract--The acquisition of selected motor skills was studied in a 40-year-oldman with a
severeamnesticsyndromeresultingfrom a bilateral medialtemporal-loberesectioncarriedout
13 years before. On Rotary Pursuit, Bimanual Tracking, and Tapping, his scores improved
from sessionto session,and on the one task whereit was feasibleto retest severaldaysafter the
end of training (Rotary. Pursuit), he showed complete retention. Theseresults imply that
motor learningcan be mediated by brain structures still intact in this patient. The additional
finding that he was inferior to normal men of his age on two tasks, in both initial and final
levels of performance, is attributed to his relatively long reaction time rather than to the
memory deficit.
OBSERVATIONSin normal man suggest that the development of motor skill is qualitatively
different from most kinds of learning. In contrast, for example, to rote learning of cognitive
matelial, quite complex motor skills (such as skating, swimming, pronouncing a foreign
language, dancing, and piano playing) ale usually acquired most efficiently in childhood,
are extremely difficult to eradicate through disuse, and show little relationship to the level
of general intellectual function. In view of such distinctions it is reasonable to postulate
that motor learning may be mediated, at least in part, by different neural structures than
those implicated in other forms of learning. A clue that this may be the case stems from
an analysis of the performance of SCOVILLE'S[16] patient, H.M., in a wide variety of
learning situations.
This man was operated upon in 1953 for the relief of incapacitating non-focal seizures,
the anterior hippocampus, the hippocampal gyrus, uncus, and amygdala being removed
bilaterally by means of a frontal approach permitting the temporal neocortex to be spared.
Consequent to this procedure, H.M. showed a profound anterograde amnesia which has
persisted essentially unchanged. The retrograde amnesia is now restricted mainly to the
year before his operation, and there is no general intellectual loss or deficit in attention
span.
On a wide variety of tasks, which included flee recall of short prose passages and complex
patterns, face recognition, continuous recognition of visual patterns and of verbal material,
paired-associate learning, and maze learning, H.M. failed to show any significant retention
of the material presented to him. Nevertheless, in 1959, H.M. performed 39 trials on a
mirror-drawing task and showed steady improvement (indicated by reduced time and
error scores for both hands) over a three-day period [9], although on the second and third
days he was not aware of having done the task before. Similarly in 1962, while unable
to learn the correct sequence of turns in a 10-choice tactual maze, H.M. gradually reduced
255
256 S UZANNE CORKIN
his time scores over 80 trials [4]. On the basis of these two findings, it was hypothesized
that other motor skills could also be acquired by patients with bilateral lesions of the
medial temporal structures [10].
To explore this possibility further, it was decided to train H. M.on a few other motorlearning
tasks, including two on which trials could be distributed over several days, thus
permitting one to look for day-to-day improvement and to compare his rate of learning
with that of a group of normal right-handed male subjects of about the same age as H.M.
This study, the results of which are reported below, was carried out in June, 1966, at which
time H.M. was 40 years old.
METHOD
The tests chosen consisted of three motor-learning tasks (Rotary Pursuit, Bimanual
Tracking, and Tapping) and two control tasks (Reaction Time and Serial Ordering of
Digits). On Rotary Pursuit and Bimanual Tracking, training of H.M. took place over
two consecutive weeks, one week being devoted to each task. Because the normal control
subjects were tested at work, their training on each of these tasks was limited to five days.
All subjects were given the Tapping test twice, on one day only.
In one of the control procedures, a test thought to he sensitive to personal tempo,
the subject was asked to arrange lists of digits in serial order. One year after completion
of other testing described in this report, measurement of H.M.'s reaction times was made,
the purpose being to achieve a better understanding of his reduced efficiency, as compared
to that of normal control subjects, on Rotary Pursuit and Bimanual Tracking.
The subject was not told his actual scores on any test, either from trial to trial or from
day to day, but it was possible for him to derive information about his performance from
the clicking of the automatic timers and counters, which recorded his time and contact
scores.
Motor-learning tasks
1. Rotary Pursuit. The apparatus is shown in Fig. 1. The subject was instructed to
hold the stylus between the thumb and index finger of his preferred hand and to rest the
tip of the stylus on the metal target. He then was told that in a few seconds the disc would
begin turning and that he should keep the stylus in contact with the target until it stopped.
During each trial the disc rotated at 45 rev/min for 20 sec. After one trial with the preferred
hand, the subject switched to his non-preferred hand, continuing to alternate hands in this
way until he had completed four trials with each hand. The intertrial interval was 20 sec.
It should be noted that the task was not the same for left and right hands because the disc
always rotated in a clockwise direction. For each trial, the time on target and the number of
contacts with the target were recorded. Testing was carried out twice a day on the first
two days and once a day thereafter.
2. Bimanual Tracking. After all training sessions on the Rotary-Pursuit apparatus
had been completed, subjects began the tracking task, the apparatus being a memory
drum adapted for this purpose (Fig. 2). The aluminum drum was painted flat black except
for two asymmetric tracks approximately ¼ in. wide, which the subject saw through a
horizontal slit 83-in. high. Holding a stylus in each hand, he was required to place the lefthand
stylus on the left-hand track and the right-hand one on the right-hand track, and to
maintain these contacts while the drum rotated in discrete steps every 2 sec, 1 sec, or ½sec.
ACQUISITION OF MOTOR SKILL AFTER BILATERAL MEDIAL TEMPORAL-LOBE EXCISION 257
Each session consisted of six 20-see, trials, two trials being given at the 2-sec speed, two
at the 1-see speed, and two at the ½-sec speed. There were two testing sessions per day,
and both time and contact scores were obtained for each hand on all trials.
3. Tapp&g. The apparatus for this task is shown in Fig. 3, the procedure being that
described by THURSTONE[-19] (pp. 49-51). Holding a metal stylus in his right hand, the
subject tapped each sector of the divided circle on the right as quickly as possible, in the
sequence 1, 2, 3, 4, for 30 sec. He then did the same thing with his left hand, this time
tapping the divided circle on the left. In the third stage of the task, he was required to
work with both hands simultaneously, again for 30 sec, always tapping in the order 1, 2, 3,
4. It will be noted that these numbers are arranged differently on the left and right sides
of the tapping board; yet in the bimanual condition, the counter recording the contacts
registered only when the sectors with corresponding numbers were hit simultaneously.
All subjects performed this task twice in the same day, the intervening 40-rain period
being spent in various activities outside the testing room.
Control tasks
1. Reaction Time. The subject was seated at a table with one hand supported by a book,
his index finger resting lightly on a key which operated a microswitch. At the beginning
of each trial the experimenter gave the signal, "Ready," and after 0-4 sec delay, she pushed
a silent switch to activate a Standard electric timer and one of three stimuli, one visual
and two auditory. The visual stimulus (V1) was provided by a Chicago miniature lamp
with 0.52 mean spherical candelpower, the auditory ones (A 1 and A2) by a Line mediamtone
AC-DC buzzer and by a Lafayette burglar alarm module connected to a 6-volt battery
and a speaker, respectively. By depressing the key as quickly as possible, the subject stopped
the timer and turned off the stimulus. Forty consecutive trials were given with each stimulus,
in the order Vb Ab A2, V1. Within each group of forty trials, the subject alternated
right (R) and left (L) hands as follows: R-L-L-R-L-R-R-L, each letter representing five
trials with the corresponding hand.
2. Serial Ordering of Digits. In doing this pencil and pape~ task, the subject utilized
test forms similar to that shown in Fig. 4. He was instructed to rank each group of seven
digits starting with the lowest digit in that group. Thus, in the first set of blanks provided,
the subject would write 1 2 5 5 6 6 8. During the 15 rain that he was required to work on
this task, a light would flash every 60 sec, whereupon the subject was supposed to draw
a vertical line after the digit he had just written, and then resume the task. These time
markers made it possible to calculate the number of lines completed in each of the three
5-min periods. Because of H.M.'s memory impairment, each time the light flashed the
examiner told him to draw a line.
RESULTS
The results of the present study give additional support to the notion that the medial
temporal-lobe structures are not necessary for the acquisition of motor skill. On the two
tasks which involved learning over several days (Rotary Pursuit and Bimanual Tracking),
H.M.'s performance improved from session to session and from day to day. Similarly,
his tapping scores after a 40-rain rest interval were superior to those recorded before it.
258
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FIO.4. Test~rm~rSerialOrderingofDigits.
In contrast, H.M. was inferior to normal subjects on the two control tasks (Reaction Time
and Serial Ordering of Digits), suggesting a slowness of tempo which presumably is independent
of the memory deficit observed in learning situations which are not primarily
motor.
ACQUISITION OF MOTOR SKILL AFTER BILATERAL MEDIAL TEMPORAL-LOBE EXCISION 259
Motor-learning tasks
In the presentation of results for Rotary Pursuit and Bimanual Tracking the scores
for right and left hands have been combined for visual simplicity, since the focus of this
report is on changes in over-all level of performance rather than on hand differences.
In analyzing these data, the Mann-Whitney U test 1-18] was used to compare the scores
of the normal control subjects on the first session with their scores on the last.
1. Rotary Pursuit. Figure 5 shows the Rotary-Pursuit time scores for H.M. as compared
with the mean scores for seven normal control subjects, all right-handed males who ranged
in age from 34 to 43 years. There is a significant increase in H.M.'s time-on-target from
Session 1 to Session 9 (U= 5, p = 0.001) and for the normal control subjects from Session 1
to Session 7 (T= 0, p = 0.02). Nevertheless, the two curves differ in that the control subjects'
initial level of performance was superior to that of H.M., and their scores continued to
rise over the five days of testing, whereas H.M. reached asymptote on Session 4.
20
m
_--* NORMAL CONTROL SUBJECTS41--
o,- o.-
/av..~"
/
f/
/
. ~ r. _.//--4 CASE H.M.
I i i I f I q i ,~t" I
2 3 4 5 6 7 8 9 10 SESSION
II III IV V VI VII XIV DAY
FIG. 5. Rotary Pursuit: time scores.
The Rotary-Pursuit contact scores (Fig. 6) are more meaningful if one first considers
the requirements of the task. In the initial phase, the subject learns to get back on target
quickly once he has lost it, but as he becomes more proficient, he stays on target for longer
periods of time, the problem then being less one of recovering quickly as of not losing
contact. A comparison of the Rotary-Pursuit contact scores for H.M. and for the normal
control subjects (Fig. 6) shows an opposite trend in the two sets of data; that is, H.M.
increased his number of contacts with the target from Session 1 to Session 9
(U=0.5, p <0.001), but the control subjects learned to make significantly fewer contacts
from Session 1 to Session 7 (T= 0, p = 0.02). It, therefore, seems as if H.M.'s performance
reflects an increasing efficiency in getting back to the target when he has lost it, whereas the
performance of the normal control subjects shows a steady decrease in the number of
departures from the target.
260
45
--i 35
25
~ 0
~ UZANNE CORKIN
*"".. ~/~...4 CASEH.M.
",,....=/''w" ",, NORMALCONTROLSUBJECTS
I I I I I I I I /~( I
2 3 4 5 O 7 8 9 10 SESSION
II III IV V VI Vii XIV DAY
FzG.6. Rotary Pursuit: contact scores.
Figures 5 and 6 also show H.M.'s retention scores (Session 10) obtained one week
after the final training session. It is clear that his performance on Day XIV was as efficient
as on Day VII, no opportunity for practice on this task having been given in the interval.
2. Bimanual Tracking. Figure 7 shows the time scores for the same normal control
subjects who performed the Rotary-Pursuit task, and for H.M. The scores obtained at the
½-see speed were found to be the most informative because at the lower speeds the normal
control subjects consistently achieved near-maximum time scores after only a few sessions.
20
~15
i ,°
z 5
5:
.~ =--~ * - -- ~ _- --,,- -- -4 NORMALCONTROLSUBJECTS
.e
I I I
2 3 4
I I I I I I I J I I
5 6 7 8 9 10 11 12 13 14
SESSION
FIG. 7. Bimanual Tracking: time scores.
ACQUISITION OF MOTOR SKILL AFTER BILATERAL MEDIAL TEMPORAL-LOBE EXCISION 261
The score indicated on the graph for each session, therefore, is the mean time on track
during two 20-see trials in which the drum moved every half sec. There was a significant
improvement in H.M.'s time scores from Session 1 to Session 14 (U=5, p=0.001), and
although the curve for the normal control subjects is flatter, they also showed a significant
increment in level of performance (T=0, p=0.02). As in the Rotary-Pursuit task, H.M.'s
performance was inferior to that of the normal control subjects throughout training,
and his scores were more variable.
The contact scores for the same trials are plotted in Fig. 8. The two curves are clearly
distinct but, unlike those for Rotary Pursuit, show similar trends. The decrease in mean
number of contacts with the tracks, from initial to final levels, is significant in both cases
(H.M. : U= 5, p = 0.001 ; Controls: T= 0, p = 0.02). Nevertheless, H.M.'s contact scores
were within the range of scores for the normal control subjects on Sessions 1 and 2 only,
and as training progressed, his scores fell farther away from the normal range. It was not
I0~
~.......-~CASE H.M.
~-~ "~---* NORMALCONTROLSUBJECTS
~ I I I I I I I I I I f
2 3 4 5 6 7 8 9 10 11 12 13 14
SESSION
FIG. 8. Bimanual Tracking: contact scores.
possible to test for retention of Bimanual Tracking because the patient was discharged
soon after the completion of training.
3. Tapping. Table 1 shows the test-retest scores for unimanual and bimanual conditions.
H.M.'s initial test scores were well within the range of scores for normal control
subjects of the same age. His retest scores, obtained 40 minutes later, showed improvement,
this being especially marked in the unimanual conditions.
Table 1. Tapping scores for right-handed male subjects (age range: 35--45years)
Subjects Test Right hand Left hand Both hands
Mean Range Mean Range Mean Range
Case H.M. 1st 90.0 - 90.0 - 20.0 -
2nd 103.0 - 103.0 - 22.0 Normal
control 1st 102.2 74-131 97.5 63-136 20.2 12-30
(N=10) 2nd 109.2 76-144 107.5 75-144 25.0 21-34
262 SUZANNE CORKIN
Control tasks
1. Reaction Time. The data for the four blocks of 40 trials are given in Table 2. The
mean age of this normal control group, all right-handed men, was 40.7 years (range: 37--44
years), H.M.'s age being 41 years at the time of this testing. Not only are H.M.'s mean
reaction times well above those of the normal control group, but his mean scores fall
outside the range of mean scores achieved by the control subjects, the single exception
occurring in the first block of V~ data where one normal subject was slower than H.M.
Like the normal control group, H.M. required less time to respond to the auditory stimuli
than to the visual. The slight increase in his mean visual reaction times for Trials 121-160,
as compared with that for Trials 1-40, was consistent with the change seen in four of the
six normal control subjects, and is probably attributable in all five cases to fatigue.
Table 2. Reaction Time in msec averaged over40 consecutivetrials
Subjects Stimuli
V~ A1 A2 VI
Mean Range Mean Range Mean Range Mean Range
Case H.M. 270.8 -- 244.8 -- 236.8 -- 286.3 --
Normal control 220.5 189.3- 182.2 159.0- 182.4 154.8- 217.2 206.5(N=6)
276.8 215.3 198.0 241.3
2. Serial Ordering of Digits. These data are shown in Table 3; H.M.'s scores are
inferior to those of male control subjects whose ages ranged from 38 to 43 years. Most
remarkable, however, is the drop in H.M.'s performance for the third 5-rain period. This
reduction in efficiency may have been due to the cumulative effect of periodic interruptions
of his work with reminders to draw a line in response to the blinking light. During the
last 5-rain period he appeared unusually restless at these times and complained of being
"mixed up."
Table 3. SerialOrdering of Digits: Number of linescompletedper five-minuteperiod
Subjects 1-5 Min 6-10 Min 11-15 Min
Mean Range Mean Range Mean Range
Case H.M. 25.0 -- 25.0 -- 18.0 --
Normal control (N=6) 37.8 28--48 40.0 30-49 40.3 28-48
DISCUSSION
The primary finding of this study is the clear evidence of H.M.'s ability to acquire
certain motor skills despite a severe impairment in learning other kinds of material. On
Rotary Pursuit, Bimanual Tracking, and Tapping, his scores improved from session to
session, and on the one task where it was feasible to retest several days after the end of
training (Rotary Pursuit), he showed complete retention. These results imply that motor
learning involving visually- and proprioceptively-guided movements can be mediated te
some extent by brain structures which are still intact in H.M.
ACQUISITION OF MOTOR SKILL AFTER BILATERAL MEDIAL TEMPORAL-LOBE EXCISION 263
A dissociation between visual and kinesthetic memory systems, consistent with the
findings obtained in the present study, has been proposed recently by POSNER [12, 13]
and POSNERand KONICK [14]. They found no increase in the extent to which subjects
forgot the location of a visually-presented position in space over a 20-sec rest interval,
whereas reproduction of the distance of a hand movement without visual guidance became
increasingly inaccurate over a 20-sec rest interval. Nevertheless, in POSNER'Sexperiments the
unequal difficulty of the visual and kinesthetic memory tasks and the greater similarity
of the various interpolated activities to the visual than to the kinesthetic task makes his
results less than definitive.
The contrast between storage of motor and other input can be extended by considering
differences in long-term retention of the respective responses. In general, retention of a
variety of motor skills is very high, even for no-practice intervals of up to two years, and
relearning is rapid (for reviews see Ill, Chap. 8, and [81). On the other hand, verbal
material is typically forgotten much more quickly [7, 201. The few instances in which
motor learning dissipates rapidly ([11, pp. 236-237; [81) are those in which the task
has a large verbal or other non-motor component.
The present study suggests that H.M. is somewhat inferior to normal subjects of his
age on some of the motor tasks, in both initial and final levels of performance. This impairment,
which is probably unrelated to the memory deficit, seems to be confined to
tasks whele his rate of movement is controlled by the apparatus (as in Rotary Pursuit and
Bimanual Tracking), for on tasks where H.M. can set his own rate of performance (such
as Mirror Drawing and Tapping) his scores approach more closely those of normal control
subjects.
A possible explanation of this interesting discrepancy between the two types of tasks
is that in Rotary Pursuit and Bimanual Tracking, unlike Tapping, reaction time is relevant
[151. Proficiency in these tasks is partially dependant upon being able to return quickly to
the target or track whenever contact is broken. H.M.'s reduced time-on-target is, therefore,
understandable in view of his relatively long reaction times, which were measured independently
with standard reaction-time procedures. Patients with cerebral lesions have previously
been reported to have longer reaction times than control subjects [3, 51, and extending this
finding ARRIGONIand DE RENZI [21 have suggested that reaction time is positively correlated
with lesion size.
Not only is H.M. slow in responding to a particular stimulus, his rate of spontaneous
activity is also low, and this may have contributed to his poor performance on Rotary
Pursuit and Bimanual Tracking. Moreover, on the serial ordering task, in which he had
to arrange strings of seven digits in rank order, he completed far fewer items than did the
normal control subjects. Although it is possible that the memory deficit forced him to
refer back to the original string of digits more often than did the control subjects, it is
more likely that his natural slowness of tempo was the major determinant of his low score.
This trait was also characteristic of SCOVILLEand MILNER'S [171 patient D.C., who underwent
a bilateral medial temporal-lobe removal combined with orbital undercutting, and of
PENFIELDand MILNER'S Ill I cases P.B. and F.C., who had both undergone left temporal
lobectomies, and in addition manifested electrographic abnormality in the right temporal
lobe. These inter-patient similarities suggest that the low activity rate may be attributable
to the medial temporal-lobe lesion rather than to a pre-nlorbid characteristic.
It seems unlikely that H.M.'s reduced efficiency on certain motor tasks is directly
attributable to his severe amnestic syndrome, but it is possible that the two deficits are
264 SUZANNECORKIN
cumulative. Thus, although the patient recognized the apparatus from day to day, it is
unlikely that he retained any impression of how well he had done on the task the day
before. He was not always trying to improve upon yesterday's performance (as were the
normal control subjects) because he could not remember what yesterday's performance
was. In addition, he might have been less efficient in predicting the irregular shifts in the
two tracks encountered in the bimanual task, although the extent to which this strategy
was employed by either the normal subjects or H.M. was not determined.
Anecdotal evidence obtained in addition to the quantitative measures described in
this report suggests that "testing-habits" [6] were also retained from one day to the next
by H.M. At the beginning of each Rotary-Pursuit and Bimanual-Tracking test session
he was allowed to look at the apparatus and then asked to describe the task. His memory
for the Rotary-Pursuit task, though somewhat inaccurate, was consistent in specifying
that he had to touch the stylus to the target in order to stop the disc fl'om turning. On
one occasion he further stated that he was not supposed to "touch that spring part" on
the stylus, something that he had in fact been reminded about several times before. H.M.'s
description of the Bimanual-Tracking task was consistently accurate from Session Ill on.
It is interesting that a similar sparing of testing-habits was observed by GLICKSTEINand
SPERRY [6] under very different conditions. They found that split-brain monkeys, though
failing to show intermanual transfer of somesthetic discriminations, did show consistent
transfer of the general testing procedure, which involved reaching out and feeling the two
discriminanda before selecting one or the other.
The dissociation of different levels of memory, seen in H.M., is relevant to the study of
normal memory function. H.M. performs normally on short-term memory tasks ([10] ; see
also SIDMANet al. and WmKELGRENthis issue), but he shows little evidence of being able
to establish new long-term memory traces; this impairment, in turn, contrasts with his
ability to acquire motor skill and to remember certain testing-habits from day to day.
The pattern of breakdown suggests that there is more than one set of neural structures
concerned with memory, and one wonders to what extent the corresponding physiological
processes also differ. Electrophysiology has given very few clues as to what the processes
may be, and the data that are available have little relevance to the analysis of complex
behavior. In the meantime, it would be helpful to know if there is a motor analogue of
H.M.'s memory deficit, the subject showing no impairment in initial level of performance
but an inability to improve his skill beyond this point. I do not know of any such cases
being reported, which may mean that the very specific and severe deficit in motor learning
hypothesized does not exist, or that no one has bothered to look for it. What we do know
is that the medial parts of the temporal lobes are not necessary for the acquisition of motor
skill, but which neural structures are critical for such behavior remains to be answered.
Acknowledgments--This investigationwas snpported by grants from the JOHNA. HARTFORDFoundation
and the National Institutes of Health (MH 05673), both to Professor H.-L. TEUBER,and by U.S.P.H.S.
Grant FR88 to the M.I.T. Clinical Research Center. The author is indebted to Dr. BRENDAMILNERand
Mr. L. B. TAYLORfor supplyingthe Tapping data, and to the Development Corporation of America for
permission to test employeesduring businesshours. The measurement of H.M.'s reaction times was done
at the Hartford Regional Center, and the hospitality of its staffis gratefullyacknowledged. Dr. E. PERRET
kindlyprovidedthe specificationsfor the Bimanual-Trackingapparatus, and the test form for SerialOrdering
of Digits. Special thanks are given to Dr. W. B. SCOVJLLEfor continued interest and cooperation in the
follow-up studies of his patient, H.M. Valuable criticism of the manuscript was given by Dr. BRENDA
M1LNER,Professor H.-L. TEUBER,and Mr. J. LACKNER.
ACQUISITION OF MOTOR SKILL AFTER BILATERAL MEDIAL TEMPORAL-LOBE EXCISION 265
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R6sum6--L'acquisition de certaines habilet6s motrices rut 6tudide chez un sujet de 40 ans
prdsentant un grave syndrome mn6sique rdsultant d'une r6section bilat6rale de la partie interne
des lobes temporaux, rdsection pratiqu6e 13 anndes auparavant. Sur des tests de poursuite
rotatoire, de poursuite bimanuelle et de "tapping," ses scores s'am61ioraient de sdance en
sdance et dans la seule tache off il 6tait possible de le retester plusieurs jours apr6s la fin de
I'entrainement (poursuite rotatoire), il montrait une r6tention compl6te. Ces rdsultats
impliquent que l'apprentissage moteur peut ddpendre des structures c6rdbrales encore intactes
chez ce malade. En outre, le fait qu'il 6tait inf6rieur aux normaux de son ~.geaux deux 6preuves,
fl la fois dans les niveaux, initial et final, de performances, est attribu6 au relatif allongement du
temps de r6action plut6t qu'au d6ficit mn6sique.
Zusammenfassung--Der Neuerwerb einiger ausgew/ihlter motorischer Handfertigkeiten wurde
bei einem 40-j~ihrigen Mann mit einem schweren amnestischen Syndrom untersucht, das aus
einer bilateralen medialen Temporallappenresektion resultierte, die 13 Jahre vor dem Versuch
ausgeftihrt worden war. Bei drei Aufgaben, kreisf6rmiger Handnachftihrbewegung (Rotary
Pursuit), beidh/indigem Nachfolgen, und Klopfen, verbesserten sich seine Leistungen yon einern
Mal zum anderen. An der einen Aufgabe, der kreisf0rmigen Handnachftihrbewegung (Rotary
Pursuit), an dee man ihn nach einigen Tagen wieder priafen konnte, zeigte er, dass er die Aufgabe
vollkommen behalten hatte.
Die Ergebnisse lassen darauf schliessen, dass motorisches Lernen durch Hirnstrukturen
vermittelt werden kann, die bei diesem Patienten noch intakt sind. Die zus~itzlicheBeobachtung,
dass er schlechter als ein normaler Mann seines Alters an zwei der Aufgaben abschnitt, nicht
nur im Anfangsstadium, sondern auch im Endstadium seiner Leistungen, wird eher seiner
relativ langen Reaktionszeit als seinem Ged~ichtnisausfall zugeschrieben.