Rapid plastic changes of human primary motor cortex with repetitive motor practice and transcranial magnetic stimulation

Excitability changes of human primary motor cortex are assumed to be associated with motor learning processes. To examine motor behavioral and neural mechanisms in these processes, the adaptive motor learning processes of the index finger abduction were investigated using motor evoked potential (MEP) elicited from the first dorsal interosseous and extensor carpi radialis muscles. Practice effects were examined on changes of MEP amplitudes elicited from these muscles during motor imagery. Given general consensus that the MEP amplitude change during motor imagery is a useful parameter reflecting changes in excitability of the human primary motor cortex, the present results, that MEP amplitudes of both muscles increased with repeated practice by the index finger abduction and that magnitudes of MEP amplitudes of both muscles (motor learning curves) were clearly different, suggested that participation of the muscles performing the index finger abduction gradually changed with practice. Short-term plastic changes of human primary motor cortex occur with repetitive practice and such adaptive change in human primary motor cortex is expressed in human voluntary movement that becomes more automatic.     

EMG and motor performance changes with practice of a forearm movement by children

The purpose of this research was to investigate changes in the control of movement, using EMG and kinematic variables, over practice by children. Children in three age groups, 7, 9, and 11 yr., performed 60 trials of an elbow-flexion movement. Correct movements consisted of a 60 degrees angular movement of the forearm in 800 msec. The analysis of biceps brachii and triceps brachii muscle EMG activity, movement displacement and timing error, and movement velocity patterns indicated changes in motor performance with practice. All age groups improved performance with practice and also exhibited a decrease in biceps EMG activity with practice. Only movement-time error and time to peak triceps muscle activity differed between the age groups. The 11-yr.-old group significantly altered the timing of the antagonistic response to stop the movement over the practice session. This change is suggested to be related to the greater information-processing ability of these children and the development of appropriate movement strategies to perform the movement task successfully. Other changes observed in the EMG data appear similar to changes observed in studies of adults.     

Changes in excitability in motor cortex (representation of foreleg) of the dog depending on signal signification of flexor reaction during elaboration of trans switching

Excitability in a cortical representation of a foreleg was determined during elaboration of transswitching in dogs in three variations depending upon the stimulus used as a Conditioned stimulus (CS). If the flexor reaction to direct stimulation of the motor cortex was used as a CS, excitability changes of opposite signs appeared in the cortical representation of the foreleg, the threshold of flexion decreased in the alimentary situation and increased in the defense situation. Such changes in excitability were observed during instrumental conditioned transswitching. If subthreshold stimulation of the motor cortex was used as the CS, the threshold of flexion increased in both situations in approximately equal degree.     

Rapid modulation of distributed brain activity by Transcranial Magnetic Stimulation of human motor cortex

This paper reviews the effects of single and repetitive transcranial magnetic stimuli (rTMS) delivered to one cortical area and measured across distributed brain regions using electrophysiological measures (e.g. motor thresholds, motor evoked potentials, paired-pulse stimulation), functional neuroimaging (including EEG, PET and fMRI) and behavioural measures. Discussion is restricted to changes in excitability in the primary motor cortex and behaviour during motor tasks following transcranial magnetic stimulation delivered to primary motor and premotor areas. Trains of rTMS have lasting effects on the excitability of intrinsic and corticofugal neurones, altering the responsiveness of local and remote sites. These effects lead to distributed changes in synaptic activity at rest, and during a range of motor tasks. It is possible to impair or improve performance following rTMS, but for most simple motor tasks performance is unaltered. Changes in distributed activity observed with functional imaging during motor behaviour may represent compensatory activity, enabling maintenance of performance; stimulation of additional cortical areas appears to impair performance. A detailed understanding of the distributed changes in excitability following rTMS may facilitate future attempts to modulate motor behaviour in the healthy brain and for therapeutic purposes.     

The somatotopy of speech: Phonation and articulation in the human motor cortex

A sizable literature on the neuroimaging of speech production has reliably shown activations in the orofacial region of the primary motor cortex. These activations have invariably been interpreted as reflecting “mouth” functioning and thus articulation. We used functional magnetic resonance imaging to compare an overt speech task with tongue movement, lip movement, and vowel phonation. The results showed that the strongest motor activation for speech was the somatotopic larynx area of the motor cortex, thus reflecting the significant contribution of phonation to speech production. In order to analyze further the phonatory component of speech, we performed a voxel-based meta-analysis of neuroimaging studies of syllable-singing (11 studies) and compared the results with a previously-published meta-analysis of oral reading (11 studies), showing again a strong overlap in the larynx motor area. Overall, these findings highlight the under-recognized presence of phonation in imaging studies of speech production, and support the role of the larynx motor cortex in mediating the “melodicity” of speech.     

Multiple measures of motor lateralization in human primates (Homo sapiens)

Laterality was assessed in 100 human (Homo sapiens) subjects through the use of five measures of motoric behavior in three categories: locomotor, manual, postural. Locomotor measures included leading limb for initiation of walking and whole-body turning. Performance and questionnaire measures were used to assess lateral hand bias. Postural bias was assessed as the weight distribution in quiet standing. Population-level biases on the manual and leading limb measures were to the right; on posture and turning, to the left. Locomotor measures were found to be altered by marching experience. Only the manual measures were correlated. We compare the results with those of nonhuman primate studies that have used similar measures and discuss some patterns of laterality common to human and nonhuman primates.     

Genograms in counselling practice: A review (Part 1)

Genograms are an important clinical tool for many counsellor, therapists and other health care professionals and can be used for assessment, gathering information on family relationships and exploring themes in counselling practice. This article reviews the recent literature on genograms and examines the efficacy and use of this tool from a number of perspectives including the use of genograms in health care, psychological counselling and in genetic counselling. The predictive value, and future development of the use of the genogram in counselling are also discussed.     

Neurophysiologic markers of primary motor cortex for laryngeal muscles and premotor cortex in caudal opercular part of inferior frontal gyrus investigated in motor speech disorder: a navigated transcranial magnetic stimulation (TMS) study

Transcranial magnetic stimulation studies have so far reported the results of mapping the primary motor cortex (M1) for hand and tongue muscles in stuttering disorder. This study was designed to evaluate the feasibility of repetitive navigated transcranial magnetic stimulation (rTMS) for locating the M1 for laryngeal muscle and premotor cortical area in the caudal opercular part of inferior frontal gyrus, corresponding to Broca’s area in stuttering subjects by applying new methodology for mapping these motor speech areas. Sixteen stuttering and eleven control subjects underwent rTMS motor speech mapping using modified patterned rTMS. The subjects performed visual object naming task during rTMS applied to the (a) left M1 for laryngeal muscles for recording corticobulbar motor-evoked potentials (CoMEP) from cricothyroid muscle and (b) left premotor cortical area in the caudal opercular part of inferior frontal gyrus while recording long latency responses (LLR) from cricothyroid muscle. The latency of CoMEP in control subjects was 11.75 ± 2.07 ms and CoMEP amplitude was 294.47 ± 208.87 µV, and in stuttering subjects CoMEP latency was 12.13 ± 0.75 ms and 504.64 ± 487.93 µV CoMEP amplitude. The latency of LLR in control subjects was 52.8 ± 8.6 ms and 54.95 ± 4.86 in stuttering subjects. No significant differences were found in CoMEP latency, CoMEP amplitude, and LLR latency between stuttering and control-fluent speakers. These results indicate there are probably no differences in stuttering compared to controls in functional anatomy of the pathway used for transmission of information from premotor cortex to the M1 cortices for laryngeal muscle representation and from there via corticobulbar tract to laryngeal muscles.     

Olfactory discrimination of estrous condition by the male golden hamster (Mesocricetus auratus)

After repeated exposure to receptive and nonreceptive females, male golden hamsters were tested for olfactory preferences in a four-choice olfactometer. Males discriminated between the odor of anesthetized females in different stages of their estrous cycle when the airstreams carrying the stimulus odors were diluted. Previous failures to demonstrate such an ability were probably due to ceiling effects resulting from laboratory testing. Males preferred the odor of females on the day before receptivity (a day coincident with maximal scent marking by the female) and least preferred the odor of females on diestrus-1 (the day on which females attacked and chased males during pretesting encounters). Detection and quick response to an impending estrus would be especially important for males of a solitary and promiscuous species in which there is a first male mating advantage.     

Noninvasive brain stimulation over M1 and DLPFC cortex enhances the learning of bimanual isometric force control

Motor learning plays an important role in upper-limb function and the recovery of lost functionality. This study aimed to investigate the relative impact of transcranial direct current stimulation (tDCS) on learning in relation to the left primary motor cortex (M1) and left dorsolateral prefrontal cortex (DLPFC) during bimanual isometric force-control tasks performed with both hands under different task constraints. In a single-blind cross-over design, 20 right-handed participants were randomly assigned to either the M1 group (n = 10; mean age, 22.90 ± 1.66 years, mean ± standard deviation) or the DLPFC group (n = 10; mean age, 23.20 ± 1.54 years). Each participant received 30 min of tDCS (anodal or sham, applied randomly in two experiments) while performing the bimanual force control tasks. Anodal tDCS of the M1 improved the accuracy of maintenance and rhythmic alteration of force tasks, while anodal tDCS of the DLPFC improved only the maintenance of the force control tasks compared with sham tDCS. Hence, tDCS over the left M1 and DLPFC has a beneficial effect on the learning of bimanual force control.     

Sense of body ownership in patients affected by functional motor symptoms (conversion disorder)

Background and aimPatients with functional neurological symptoms are commonly seen in neurological practice. Nevertheless their aetiopathology remains unclear. We have recently shown that patients affected by functional motor symptoms (FMS) present lower interoceptive awareness and higher alexithymia levels than healthy controls. Nevertheless sense of body ownership has never been studied in FMS patients.The aim of the present study was to systematically investigate the sense of body ownership, with the rubber hand illusion (RHI) paradigm, in patients with FMS and healthy controls.Materials and methodsWe included in the study 16 patients with FMS and 18 healthy controls (HC). Patients and HC were asked to complete the Toronto Alexithymia Scale (TAS-20) and the self-consciousness scale (self-objectification questionnaire). All participants underwent the RHI paradigm: illusionary experience was measured by self-report and by proprioceptive alteration.ResultsA Mann–Whitney U test performed revealed that FMS (median = 2.11) participants embodied the rubber hand to the same extent than HC participants (median = 2.0, Z = −0.86, p > 0.05, r = −0.15). The same test revealed no significant difference in the Proprioceptive Drift experience between FMS (median = 0.0) and HC participants (median = −0.5, Z = −0.96, p > 0.05, r = −0.16).ConclusionsOur study revealed that sense of body ownership is not impaired in patients affected by FMS. This, together with the results from our previous experiment (studying the interoceptive awareness), supports the hypothesis that interoceptive awareness and sense of body ownership may be dissociated in patients with FMS.     

The form of the information and selective counting by ESN(M) pupils

The study springs from views on attentional deficits in retarded performers. Three experiments are reported in which educationally sub-normal (mild) category pupils and average ability pupils matched with them for mental age perform a speeded classification of cards on the basis of an enumeration of a group of items on each card. This group may be the total of the items on the card or a selected part of that total. Interest focuses upon the relationship between performance in the selective situation and the form or structure of the item group. It is argued initially that attentional patterns may be expected to vary in relation to the specific structure of the information available and the way the performer appreciates that structure. The results support this notion. ESN(M) subjects perform in a similar fashion to the matched group, even given selective instructions, when what must be counted is the whole of a vertical linear series of items. However, when what must be counted is in the form of a part of a vertical linear item series, the performance of the ESN(M) group is significantly slower than that of the matched group. In addition the matched group appear more sensitive to discontinuity within the vertical item series while the ESN(M) group may have a less differentiated approach to such information founded mainly on the appreciation of verticality. It is suggested that aspects of information available to performers must be studied in relation to the kind of whole the particular performer takes the information to be. Although retardates do not carry appropriate structural expectations from situation to situation, suitable organisation of information can be appreciated, leading to more successful performance.     

Direction of human motor responses by men and women to aversive stimulation

The frequency of extensions and flexions of the arms of 12 men and 12 women (ages 20-30 years) responding to a neutral tone or to an electric shock was recorded. Subjects had to choose between pushing or pulling a lever upon receipt of an acoustic signal which was paired or unpaired with an electric shock. They were instructed to perform either long duration movements, allowing for on-line control of the execution, or short duration movements with prior specification of amplitude. Regardless of duration of movements, the aversive signal increased the frequency of extensions and intraindividual variability of choices of the men but decreased the frequency of extensions and intraindividual variability of choices of the women. These findings show that stimuli such as pain or fear automatically elicit patterns of terminal motor states corresponding to fight or flight, initiating processes of preparation of spatially oriented movements which are automatic and sex-typed and impair the use of the terminal cues for simultaneous preprogrammed voluntary movements.     

Angiotensin-(1-7)-induced plasticity changes in the lateral amygdala are mediated by COX-2 and NO

It is known from studies outside the brain that upon binding to its receptor, angiotensin-(1-7) elicits the release of prostanoids and nitric oxide (NO). Cyclooxygenase (COX) is a key enzyme that converts arachidonic acid to prostaglandins. Since there are no data available so far on the role of COX-2 in the amygdala, in a first step we demonstrated that the selective COX-2 inhibitor NS-398 significantly reduced the probability of long-term potentiation (LTP) induction in the lateral nucleus of the amygdala. Similarly, in COX-2^−/− mice, LTP induced by external capsule (EC) stimulation was impaired. Second, we evaluated the action of angiotensin-(1-7) in the amygdala. In wild-type mice, angiotensin-(1-7) increased LTP. This LTP-enhancing effect of Ang-(1-7) was not observed in COX-2^+/− mice. However, in COX-2^−/− mice, Ang-(1-7) caused an enhancement of LTP similar to that in wild-type mice. The NO synthetase inhibitor L-NAME blocked this angiotensin-(1-7)-induced increase in LTP in COX-2^−/− mice. Low-frequency stimulation of external capsule fibers did not cause long-term depression (LTD) in drug-free and angiotensin-(1-7)-treated brain slices in wild-type mice. In contrast, in COX-2^−/− mice, angiotensin-(1-7) caused stable LTD. Increasing NO concentration by the NO-donor SNAP also caused LTD in wild-type mice. Our study shows for the first time that LTP in the amygdala is dependent on COX-2 activity. Moreover, COX-2 is involved in the mediation of angiotensin-(1-7) effects on LTP. Finally, it is recognized that there is a molecular cross-talk between COX-2 and NO that may regulate synaptic plasticity.     

Snoddy (1926) revisited: time scales of motor learning

The authors investigated the time scales of the learning of a mirror-tracing task to reexamine G. S. Snoddy's (1926) original claim and the received theoretical view (A. Newell & P. S. Rosenbloom, 1981) that motor learning follows a power law. Adult participants (N = 16) learned the tracing task in either a normal or a reversed visual-image condition over 5 consecutive days of practice and then performed 1 day of practice 1 week later and again 1 month later. The reversed-image group's performance was poorer than that of the normal-image group throughout the practice. An exponential was the best fitting function on individual data, but the power-law function was the best fit on the group-averaged data. The findings provided preliminary evidence that 2 characteristic time scales, (a) fast, dominated by warm-up, and (b) slow, dominated by persistent change, capture individuals' performance in the learning of the mirror-tracing task.     

Visual discrimination of shape by Humans. II: (I) matrix figures and (II) minimal area changes

Two experiments are described in which an attempt was made systematically to vary two dimensional shapes according to a pre-arranged design. In the first, subjects were presented tachistoscopically with pairs of “reflexive matrix figures” whose members were either horizontally or vertically orientated; and it was found that reaction times to horizontal pairs were faster than to vertical ones, a result that is in keeping with previous findings. In the second experiment two ensembles were devised that were alike in every respect save that one group was extended or reduced vertically while the other varied horizontally. Performance was better on the vertically orientated ensemble. These findings are briefly related to former studies and the pre-eminence of vertical symmetry is underlined.     

The gateway hypothesis of rostral prefrontal cortex (area 10) function

Rostral prefrontal cortex (PFC) is a large brain region, and is unusually large in humans. Therefore, it seems likely that it might support functions that are central to cognition. However, until recently, almost nothing was known about what these functions might be. The 'gateway hypothesis' places these abilities at the centre of human mental processing. It maintains that rostral PFC supports mechanisms that enable us to attend, to a novel degree, either to environmental stimuli, or by contrast, to self-generated or maintained representations (i.e. the 'thoughts in our head'). In this way, investigations into the functions of rostral PFC will reveal key new insights into how human and non-human mental abilities differ.     

Influence of perturbation induced by an anticipated load on human motor regulatory systems.

To investigate how human motor regulatory systems are modified by prior knowledge of a predictable external perturbation, six normal human subjects, each when sitting on a chair, were required to maintain a stable elbow flexion angle (90 degrees) while different weight perturbations were applied (0.5 kg or 2-kg loads). Loads were applied either by the experimenter Without Anticipation or With Anticipation by the subject's own contralateral hand. Acceleration of the forearm movement (elbow extension and flexion) by loads and electromyograms (EMGs) of the biceps brachii (BB) and the triceps brachii (TB) muscle were recorded. Under With Anticipation conditions, preceding EMG activities of BB and TB muscles prior to the onset time of perturbation were clearly observed. Furthermore, the amount of these preceding EMG activities was larger in the heavy load perturbation than in the light load perturbation. Under Without Anticipation conditions, however, these preceding EMG activities were not observed. In the preceding EMG activities, EMG bursts (latency 20 msec.) of a presumed stretch reflex induced by the perturbation were clearly observed. Thus, the function of anticipatory adjustment of mainitaining the elbow angle definitely appears to optimize limb stability in the case of the mechanical self-applied perturbation. Furthermore, the extent of the anticipatory adjustment of the elbow angle was dependent on the predicted magnitude of load.