Behavioural indexes of movement imagery ability are associated with the magnitude of corticospinal adaptation following movement imagery training.

Movement imagery (MI) is a cognitive process wherein an individual simulates themselves performing a movement in the absence of physical movement. The current paper reports an examination of the relationship between behavioural indexes of MI ability and the magnitude of corticospinal adaptation following MI training. Behavioural indexes of MI ability included data from a questionnaire (MIQ-3), a mental chronometry task, and a hand laterality judgment task. For the measure of corticospinal adaptation, single-pulse transcranial magnetic stimulation (TMS) was administered to elicit thumb movements to determine the representation of thumb movements before and after MI training. MI training involved participants imagining themselves moving their thumb in the opposite direction to the dominant direction of the TMS-evoked movements prior to training. Pre/post-training changes in the direction and velocity of TMS-evoked thumb movements indicated the magnitude of adaptation following MI training. The two main findings were: 1) a positive relationship was found between the MIQ-3 and the pre/post-training changes in the direction of TMS-evoked thumb movements; and 2) a negative relationship between the mental chronometry measure and both measures of corticospinal adaptation following MI training. These results indicate that both ease of imagery and timing of imagery could predict the magnitude of neuroplastic adaptation following MI training. Thus, both these measures may be considered when assessing imagery ability and determining who might benefit from MI interventions.

Motor system activation during motor imagery is positively related to the magnitude of cortical plastic changes following motor imagery training.

Motor imagery (MI) is a cognitive motor process wherein a person consciously imagines themselves performing a movement. Previous transcranial magnetic stimulation (TMS) studies have demonstrated that physical and observational training can elicit neuroplastic adaptations in the cortical representation of movement. It has been shown that these cortical adaptations can also occur following MI training. These changes are thought to occur because of a training-dependent potentiation (i.e. increased excitability) of the trained movement representation. To test this hypothesis, the current experiment assessed the relationship between motor cortex excitability during MI and the magnitude of motor cortical adaptations following MI training. Prior to training, single-pulse TMS was used to determine the dominant direction of TMS-evoked thumb movements. The pre/post-training change in the direction of TMS-evoked thumb movements as well as the change in the first peak velocity of these thumb movements was used as an indication of the magnitude of adaptation following MI training. During the training session, participants imagined themselves moving their thumb in the opposite direction of the pre-determined dominant direction. Single-pulse TMS was also used to determine the amplitude of motor evoked potentials (MEPs) during imagined thumb movements. A strong positive relationship was found between MEP amplitude during MI of thumb movements and both measures of motor cortical adaptation following MI training. These results support the hypothesis that activation of the corticospinal motor system during MI of movements is related to the magnitude of motor cortical adaptations following MI training.

Cueing effects emerge when humans (Homo sapiens) view images of mammals (mammalia) and birds (aves).

Humans use eye- and head-gaze cues to facilitate social interactions among members of their own species. Research examining nonhuman animal-to-human cueing effects has received little attention, but may provide valuable insight into the mechanisms that have enabled species to coexist and thrive in shared environments. The objective of the current studies was to determine how gaze cues influence the attention and target detection of humans when they view images of mammals (human, orangutan, and dog; Experiment 1) and aves (owl, macaw parrot, and duck; Experiment 2). Participants were presented with an image of a forward-facing head that was suddenly replaced with an image of the head facing to the left or right, creating an apparent head rotation and change of orientation. A target appeared randomly on the left or right side of the head-gaze cue after 1 of 4 stimulus-onset asynchronies (SOAs; 100, 300, 600, or 1,000 ms). Participants were asked to indicate the location of the target by pressing a spatially corresponding key. The analysis of response times (RTs) revealed facilitatory cueing effects (RTs to cued targets were shorter than to uncued targets) across all SOAs in Experiment 1 (images of mammals). Such facilitatory cueing effects were only present at short SOAs (i.e., 100 and 300 ms) in Experiment 2 (images of aves). These findings provide initial evidence that the processing of gaze cues observed during human-to-human interactions is similar to that observed during mammal-to-human interactions, but is different in aves-to-human interactions. Alternative interpretations of the data are discussed. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Rapid motor cortical plasticity can be induced by motor imagery training.

Previous behavioural research has revealed that motor imagery (MI) can be an effective technique to generate and enhance motor learning and rehabilitation. This MI-enhanced motor performance may emerge because MI shares overlapping neural networks with movement execution and observation and leads to the activation and neuro-plasticity of the motor system. Neurophysiological studies using transcranial magnetic stimulation (TMS) have shown that physical and observational practice can elicit use-dependent, neuro-plastic changes in the cortical representation of movement. The purpose of the current experiment was to determine if similar changes in cortical representation of thumb movements could be elicited with MI training. Single-pulse TMS was provided over primary motor cortex to generate involuntary thumb movements before and after each of five training blocks. The dominant direction (flexion or extension) of TMS-evoked thumb movements was used as an index of the representation of thumb movements in primary motor cortex. During training, participants either imagined moving (experimental MI group) or physically moved (control PT group) their thumbs in the direction opposite to the dominant direction of their TMS-evoked thumb movements determined in the pre-training assessment. Both PT and MI training resulted in increases in the percentage of TMS-evoked thumb movements in the trained direction. These changes were apparent for the MI group after 900 imagery trials, whereas the changes were detectable in the PT group after 300 trials. These results indicate that MI can induce plastic changes similar to those of physical training, although more trials may be needed for these changes to occur.

Probing the time course of facilitation and inhibition in gaze cueing of attention in an upper-limb reaching task.

Previous work has revealed that social cues, such as gaze and pointed fingers, can lead to a shift in the focus of another person's attention. Research investigating the mechanisms of these shifts of attention has typically employed detection or localization button-pressing tasks. Because in-depth analyses of the spatiotemporal characteristics of aiming movements can provide additional insights into the dynamics of the processing of stimuli, in the present study we used a reaching paradigm to further explore the processing of social cues. In Experiments 1 and 2, participants aimed to a left or right location after a nonpredictive eye gaze cue toward one of these target locations. Seven stimulus onset asynchronies (SOAs), from 100 to 2,400 ms, were used. Both the temporal (reaction time, RT) and spatial (initial movement angle, IMA) characteristics of the movements were analyzed. RTs were shorter for cued (gazed-at) than for uncued targets across most SOAs. There were, however, no statistical differences in IMAs between movements to cued and uncued targets, suggesting that action planning was not affected by the gaze cue. In Experiment 3, the social cue was a finger pointing to one of the two target locations. Finger-pointing cues generated significant cueing effects in both RTs and IMAs. Overall, these results indicate that eye gaze and finger-pointing social cues are processed differently. Perception-action coupling (i.e., a tight link between the response and the social cue that is presented) might play roles in both the generation of action and the deviation of trajectories toward cued and uncued targets.

Independent Development of Imagination and Perception of Fitts' Law in Late Childhood and Adolescence.

Recent neurophysiological and behavioral research suggests perception-action systems are tightly coupled. Accordingly, Fitts' law has been observed when individuals execute, perceive, and imagine actions. Developmental research has found that (a) children demonstrate Fitts' law in imagined actions and (b) imagined movement time (MT) becomes closer to actual MT as age increases. However, action execution, imagination, and perception have yet to be assessed together in children. The authors investigated how imagined and perceived MTs related to actual MTs in children and adolescents. It was found that imagined MTs were longer than execution MTs were. Perception MTs were lower than execution MTs for children and more consistent with execution MTs for adolescents. These results suggest potential mechanistic differences in action imagination and perception.

The action-specific effect of execution on imagination of reciprocal aiming movements.

Past research has shown that the movement times of imagined aiming movements were more similar to actual movement times after the individual has experienced executing the movements. The purpose of the present study was to determine if experience with a set of movements altered the imagination of movements that were not experienced. Participants imagined a series of reciprocal aiming movements in different movement difficulty contexts (created by altering target width and movement amplitude) before and after actually executing a series of aiming movements. The range of difficulties of the imagined movements included difficulty contexts that were within (Experiment 1) or outside (Experiment 2) the range of difficulty experienced during execution. It was found that imagined movement times of movements within the range of movement difficulties experienced were more consistent with Fitts' Law after movement experience, whereas imagination of more difficult movements was not altered by experience. It is suggested that execution did not enhance imagination of more difficult movements because the relative contributions of motor planning and control to the more difficult movements were different from those in the experienced movements. Thus, the enhancement of imagination through experience might only occur when mechanisms underlying the executed and imagined movements are similar.

Effect of task-specific execution on accuracy of imagined aiming movements.

Ideomotor theory states that the neural codes that represent action and the perceptual consequences of those actions are tightly bound in a common code. For action imagination, bound action, and perceptual codes are thought to be internally activated at a sub-threshold level through action simulation. In support of this hypothesis, previous research revealed that imagined movement times (MTs) for reciprocal aiming movements were closer to actual execution MTs after the participants gained experience executing the task. The current study examined the task-specific nature of the effects of experience on imagination by determining if improvements in accuracy in the imagination of reciprocal aiming movements occur only with experience of the reciprocal aiming task or with any aiming task. To this end, one group of participants executed a reciprocal pointing task, whereas a second group executed a discrete aiming task with comparable accuracy requirements before and after imagining reciprocal aiming movements. Influence of task specificity on imagination was assessed by evaluating the changes in imagined MTs before and after execution. Consistent with previous findings, there was a reduction in imagined MTs following task execution. Critically, there was a significant time by group interaction revealing a significant pre/post reduction in imagined MTs for the group that executed the reciprocal aiming movements, but not for the group that executed the discrete aiming movements. These data support ideomotor accounts of action imagination because it appears that the imagination of a movement is affected by task-specific experience with that movement.