DECEMBER, 1974 a b s t r a c t s Brain, 97,2, 337-350. Ju n e 1974: M o to r F unctions o f the L eft H em isphere, by D. K im u ra and Y. A rchibald. The autho rs query the concept th at all disorders aris­ ing from dam age to the left hem isphere are attrib u tab le to a disturbance o f representational and sym bolic func­ tions. In order to tiry to determ ine the fundam ental cause 0f apraxia they exam ined m anual dexterity in a group 0f 16 patients w ith left hem isphere dam age and 14 p a ­ tients with right hem isphere dam age. All b ''t one o f the patients were right-handed. Since a hemiplegic lim b is not testable, the group w ith left hemisphere dam age were selected prim arily on the grounds of the presence of aphasia, and only nine o f this group were hemiplegic. Apart from th e inability to test a hemiplegic limb the presence or absence of hem iplegia was not found to influence the results. , i T he tests adm inistered involved tests fo r aphasia, visuo- ^Jpatial tests and a series of specially designed m o to r tasks. T hese m o to r tasks involved firstly isolated finger flexion, secondly the copying o f hand postures and lastly the copying o f hand m ovem ents. In addition they were given the traditional tests fo r apraxia and, when it be­ came ap p aren t th at some o f the subjects had a move- ment-coDying disorder, a specially designed movem ent- recognition test w hereby instead of copying a m ovem ent the subject pointed to a picture o f it. T he authors findings showed th a t the group o f patients with left hemisphere dam age were clearly im paired in the perform ance o f complex m o to r sequences, b u t that this was so even on m o to r patterns w hich were both unfam iliar and m eaningless and w here verbal m ediation therefore played no significant role. In cases w ithout hemiplegia, w here both sides could be tested, both hands were equally im paired. T h e sam e patients w ho showed a m ovem ent-copying disorder showed no difficulty in isolated finger flexion o r in copying a static hand posture Since there was no relation to v erbal im pairm ent, the authors concluded th a t the left hem isphere has im portant functions in m otor control which are unrelated to sym ­ bolic or representational content. T hey even postulate that the speech disorders seen w ith left hem isphere damage m ay be due to a defect of m otor-sequencing rather than to a disturbance o f sym bolic o r language function. ' ^ S.I.C. McCloskey, D. I. (1973): Position sense after surgical disconnexion o f the cerebral hemispheres in m an, Brain, 96, 269-276. Summary: The author examined three patients, who had undergone surgical division of the neocortical sommissures, in order to establish w hether the disturbances o f certain sensori-m otor functions seen in such patients could be due to a disturbance of proprioceptive input. It is know n th at proprioceptive aflerents from both jo in t and muscle receptors project predominantly to the contralateral hemisphere. The article is of interest in th at the au th o r has devised tests to differentiate between jo in t sense and muscle sense. Three separate tests were carried out. T he first was a simple test of position sense involving both joint and muscle recep­ tors; the blindfolded patient was required to move one elbow in alignment with movements carried out by the examiner on the other elbow. The second test isolated muscle sense by 7 applying vibration to the tendon o f either biceps or triceps. It has been shown elsewhere that vibration applied to the tendon o f a muscle results in the illusion that th at muscle is being stretched—and the subject dem onstrates this in his movements of the other arm . T he third test isolated joint receptors by excluding any tension on the muscles operating over the distal interphalangeal jo in t o f the middle finger; this is achieved by holding the middle finger fully flexed at the proximal interphalangeal jo in t whilst fixing th e other fingers in extension. Position sense derived from the jo in t receptors o f the distal interphalangeal joint can then be tested. The results of testing in two of the three patients showed no abnorm ality, from which the deduction was made th at proprioceptive inform ation given to one side is norm ally distributed to both hemispheres despite division o f the neucortical commissures. T he abnorm al results in the third patient were thought due to the pre-operative existence of signs of widespread neurological im pairment. S.I-C. Dimitrijevic, M . R . and N athan, P . W. (1973): Studies o f Spasticity in M an— 6. H abituation, dishabituation and sensitization of tendon reflexes in spinal m an, Brain, 96, 337-354. Summary: In a previous article (abstracted in this jo u rn al in September 1971) the authors investigated the polysynaptic flexor reflex and found th at repetitive stim ulation caused discontinuation o f the reflex. The reflex could be re-activated by an increase in stimulus intensity o r by a change in rate or type o f stimulus, as well as by stimuli applied to other sites. Since th e mechanism o f habituation was thought to occur w ithin interneural pathw ays the authors were interested to examine w hether the same phenomena would occur in the m onosynaptic tendon reflex. They found th at whereas habituation and a decreasing response did occur under certain conditions o f stim ulation it happened less consistently than in the polysynaptic flexor reflex; under conditions of increased excitability o f the spinal cord, an increasing response occurred. They listed the conditions of stim ulation inducing these two, opposite, responses as the following: Decreasing response Increasing response (habituation) (sensitization) Regular or random , Regular or random , weak stimuli. strong stimuli. Regular, weak or m oderate Regular, strong stimuli at stimuli (at any rate). any rate. C onstant site o f stim ulation. R andom , moderate stimuli. Other inputs to spinal cord Changing site o f stim ulation. minimal. Other inputs to spinal cord Long periods o f stim ulation present—especially inputs originating in the bladder. Physiotherapists m ay find their observations o f assistance when dealing w ith spasticity in patients with spinal cord lesions. S.I-C. P H Y S IO T H E R A P IS T — PO RT ELIZABETH Qualified bilingual physiotherapist, h o ld er of current driver’s licence — non-sm oker — required to com m ence duties M arch, 1975. F o r fu rth er details write to: T h e Secretary, P.O. Box 12072, P o rt E lizabeth, 6006. P H Y S I O T H E R A P Y R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )