Age-related declines in motor learning are commonly attributed to changes in sensorimotor neurophysiology. However, direct links between neurochemistry, electrophysiology, and behavior are scarce. Here, we investigated whether age-related differences in GABAergic inhibition and cortical reactivity mediate age-related simple and complex motor learning declines. To do so, we employed magnetic resonance spectroscopy (MRS) and transcranial magnetic stimulation-electroencephalography (TMS-EEG) in twenty younger and eighteen older adults. Age-related effects prevailed across all measures, with robust differences in motor learning capacity, GABA levels and TMS-EEG responses. However, our analysis provided little evidence that GABAergic inhibition and cortical reactivity mediate age-related motor learning declines. Instead, both neurophysiological measures were selectively coupled to each other in a task-dependent manner, while remaining largely dissociated from motor learning outcomes. Overall, our findings demonstrate that age-related differences in local inhibitory neurochemistry, cortical reactivity and motor learning co-occur but do not appear to form a single causal pathway. These results suggest that links between local neurophysiological measures and behavioral decline may be more indirect than commonly assumed and highlight the need for integrative network approaches to study age-related behavioral processes.

Background . Normal brain function requires a dynamic balance between inhibition and excitation. While magnetic resonance spectroscopy (MRS) quantifies the chief inhibitory and excitatory neurometabolites, GABA and glutamate–glutamine (Glx), the combination of transcranial magnetic stimulation and electroencephalography (TMS–EEG) provides a complementary measure of cortical inhibition–excitation dynamics via transcranial evoked potentials (TEPs). However, the relationship between neurometabolite concentrations and TEPs is unclear. Objective . To characterize the relationship between neurometabolite concentrations and TEPs, as a function of TEP component, TMS pulse type, brain region, neurometabolite, and MRS brain state. Methods . Twenty–five young healthy adults completed a 4–day protocol. Sessions 1 and 2 involved screening, anatomical MRI, and functional MRI localization of DLPFC. In session 3, single– and paired–pulse TMS–EEG were applied over SM1 and DLPFC. Session 4 included resting–state and motor–task–related MRS of SM1 and DLPFC. Results . In SM1, task–related GABAergic tone strongly predicted early to mid–latency TEPs. In DLPFC, local early to mid–latency TEPs showed no relationship to neurometabolites, whereas late and global TEP outcomes revealed some links. The later N100 TEP was the only component consistently modulated by paired–pulse TMS. Task–related MRS measures consistently outperformed resting-state measures in predicting TEPs for SM1, while the opposite was true for DLPFC. Conclusions . Single–pulse TEPs reliably index the local inhibitory tone in SM1, with limited added value from paired–pulse paradigms. These findings support the use of single–pulse TEPs as accessible markers of cortical inhibition, especially for SM1, and may inform biomarkers and strategies for individualized neuromodulation. ### Competing Interest Statement The authors have declared no competing interest. Research Foundation - Flanders, https://ror.org/03qtxy027, 11PBG24N, G1129923N, G039821N, K174216N Hasselt Special Research Fund, BOF23INCENT18, BOF22INCENT19 Excellence of Science Grant, 30446199 (MEMODYN) KU Leuven Research Fund, C16/15/070

Gamma-aminobutyric acid (GABA) and glutamate are fundamental in neural plasticity. Motor learning is predicted by baseline levels of these metabolites and their modulation in the sensorimotor cortex (SM1), but less is known about the metabolic activity in other areas that support learning, such as the dorsolateral prefrontal cortex (DLPFC), as well as the practice-induced metabolic modulation and age-associated differences. We investigated whether: (1) motor learning induces a differential degree of metabolic modulation in the SM1 and DLPFC, (2) learning tasks with higher difficulty levels enhance metabolic modulation as compared with those with lower difficulty levels, (3) metabolic modulation during motor learning is age dependent, and (4) training-induced metabolic modulation may have a differential effect on motor learning and retention. Young (n = 25, 12 females) and older (n = 21, 10 females) human adults completed a 6 d motor learning protocol with magnetic resonance spectroscopy scans being administered before, during, and after a low and high task complexity training condition. We observed a training-induced reduction of SM1 GABA+, regardless of age and task difficulty level, but no significant changes in DLPFC. Neither region showed a significant Glx (combined glutamate and glutamine) modulation. In addition, baseline GABA+ levels predicted learning, but this effect was region and task difficulty dependent. Age-related differences emerged in the prediction of retention, with older adults showing a beneficiary role of task-induced increase in the SM1 inhibitory tone. These results highlight the complexity of metabolic dynamics in learning and retention, showing their dependency on age, brain region, and task difficulty.

Background: Experiencing repeated childhood traumatisation impacts brain structure and function in individuals with dissociative identity disorder (DID) and post-traumatic stress disorder (PTSD). Quantitative grey matter neuroimaging research has shown aberrant volumes in traumatised individuals, however studies examining white matter are sparse, particularly for DID. The present study aims to examine white matter alterations of people with trauma-related disorders. Methods: Sixty-five female participants were included in this study: 33 diagnosed with a trauma-related disorder, namely 17 with DID and 16 with PTSD, and 32 healthy control (HC) participants. All participants underwent diffusion tensor imaging (DTI) and completed dissociation and traumatisation self-report measures. White matter integrity was characterised using voxel-based analysis (VBA), with network lesion mapping used to identify the implicated grey matter end points of the VBA findings. Results: Between-group VBA comparisons showed reduced fractional anisotropy (FA) for participants with DID compared to HCs in bilateral pallidum (implicating striatal projections to pre/post central gyri), midbrain, and pontocerebellar white matter. Compared to those with PTSD, DID subjects showed increased FA in the right internal capsule and right temporal areas (predominantly implicating the inferior longitudinal fasciculus). Across DID and PTSD subjects, FA values within the aforementioned findings negatively correlated with depersonalisation, psychoform and somatoform dissociation, and/or traumatisation scores. Conclusions: Our DTI findings indicate markedly differential white matter integrity in DID compared to PTSD and HCs. This provides valuable mechanistic insights regarding a role for aberrant white matter structural integrity in traumatised female individuals with DID.

Background Dissociative identity disorder (DID) manifests with distinct trauma-avoidant and trauma-related identity states. Overtly conscious trauma-related knowledge processing is identity state-dependent. Previous research on covertly subconscious knowledge processing in DID lacks subject-specific trauma-related stimuli. Aims Our controlled functional magnetic resonance imaging (fMRI) study explored neural and behavioural differences of overt and covert knowledge processing of individualised self-relevant words in DID. Method Behavioural data were gathered while 56 participants underwent task-based fMRI: 14 with DID, 14 DID simulators and a paired control group of 14 healthy controls and 14 participants with post-traumatic stress disorder. Individuals with DID and simulators participated in a trauma-avoidant and a trauma-related identity state. Reaction times and brain activation following overtly and covertly presented individualised words were statistically analysed. Results Behavioural analyses showed a main effect of consciousness (P < 0.001). Post hoc between-group pairwise comparisons revealed slower reaction times for individuals with DID compared with simulating (P < 0.05) and paired controls (P < 0.05). Neural data analyses showed increased brain activation in frontal and parietal regions within the diagnosed DID group, especially during overt processing. Between-group comparisons mostly showed less pronounced activation in frontal, occipital and temporal areas. Conclusions The present study showed increased cognitive control during overt self-relevant knowledge processing in the trauma-avoidant identity state of DID, in line with previous research. The slower reaction times and increased frontoparietal activation shown in individuals with diagnosed DID, as compared with both control groups, support the notion of cognitive avoidance of trauma-related information in DID and further reinforce the authenticity of DID experiences.

GABA and glutamate (Glu) play pivotal roles in learning. Here, we investigated whether neurometabolites in specific sensory processing brain areas were differentially modulated depending on the type of feedback provided during motor learning and whether this was associated with behavioural progress. Fifty healthy human adults were trained on a bimanual tracking task for 5 days (Day 1 to Day 5) when receiving either concurrent (CA-VFB) or terminal (TA-VFB) augmented visual feedback. In two brain areas involved in sensory processing, that is the primary somatosensory cortex (S1) and medial temporal visual area (MT/V5), concentrations of GABA+ (GABA + macromolecules) and Glx (Glu + glutamine) were determined by acquiring magnetic resonance spectroscopy at three time points on Day 1 and Day 5: baseline (Pre-Scan), during (Mid-Scan) and after (Post-Scan) task training. Behaviourally, performance progress was more pronounced on Day 1 compared to Day 5. Neurochemically, there was a significant difference in the modulation of neurometabolites between the S1 and MT/V5 regions, specifically in Glx levels on Day 1. Additionally, there was a significant difference in the modulation of neurometabolites between Day 1 and Day 5, specifically in GABA+ levels in the S1 area and Glx levels in the MT/V5 area. Furthermore, a greater increase in individual S1 Glx levels on Day 5 correlated with larger behavioural progress. Our findings suggest that neurometabolites in task-related sensory processing brain areas show a differential modulation and contribute to long-term retention of visuomotor learning. KEY POINTS: GABA and glutamate play crucial roles in motor learning, yet how these neurometabolites are modulated within specific sensory processing brain regions based on the type of feedback provided during different phases of motor learning remains unclear. We used a repeated measures magnetic resonance spectroscopy design to measure the concentration of neurometabolites in the primary somatosensory cortex (S1) and medial temporal visual area (MT/V5) before, during and after motor training, focusing on the initial and late learning phases. In the initial learning phase, Glx (glutamate + glutamine) modulation differed between S1 and MT/V5. Furthermore, in S1, GABA modulation differed between the initial and late phases, and, in MT/V5, Glx modulation also varied between these phases. A greater increase in individual S1 Glx levels on Day 5 correlated with larger behavioural progress. These findings suggest that distinct biological changes occur in task-related sensory processing areas across different phases of motor learning.

Aging is accompanied by changes in the level of neurometabolites. However, their role in vital behavioral functions is still unclear. We aimed to explore the impact of aging on the neurochemical mechanisms underlying action selection. Young (YA) (n = 25) and older adults (OA) (n = 26) performed a simple (SRT) and a choice (CRT) reaction time tasks. Magnetic resonance spectroscopy was utilized to track task-induced modulations in GABA and glutamate in the sensorimotor cortex (SM1) and dorsolateral prefrontal cortex (dlPFC). Results showed that (i) SM1 Glx levels were higher during the SRT in the full sample, (ii) Glx modulation in the dlPFC predicted better behavioral performance in the SRT only in YA, and iii) a task-induced increase in GABA and Glx in the dlPFC was related to action selection learning in the full sample. Our findings highlight an important role of neurometabolic modulation during action selection and learning.

IntroductionOlder age is associated with alterations in executive functioning (EF). Age-related alterations in the integrity of structural brain networks may contribute to EF decline, with potential consequences for independent living. Graph theory provides powerful metrics to examine the brain's structural connectome, but few studies have investigated the relationship of EF and structural brain networks, as described by graph-theoretical measures, in older adults. We aimed to investigate the mediatory role of network characteristics for the relationship between age and EF in older adults.MethodsEighty-four older adults completed a battery of EF tasks to allow for the extraction of a latent Common-EF factor. White-matter tractograms were generated from diffusion neuroimaging using anatomically-constrained tractography (ACT) and spherical-deconvolution informed filtering of tractograms (SIFT2).ResultsFrom the resulting networks, global efficiency (reflecting integration) as well as local efficiency (reflecting segregation) were calculated. Older age was associated with worse EF and decreased global and local efficiency. Both global and local efficiency were positively correlated with EF. Local efficiency mediated the negative correlation of age and EF, whereas no such relationship was found for global efficiency. Further regional efficiency analyses identified the nodes that contributed to the mediation effect of local efficiency.DiscussionThese results shed light on the shared variability among the integrity of structural brain networks and EF at older age. A causal role of a reduced segregation in structural brain networks to support EF in older adults remains to be determined but would bear promising potential for preserving EF during aging.

IntroductionDissociative identity disorder (DID) is characterised by, among others, subjectively reported inter-identity amnesia, reflecting compromised information transfer between dissociative identity states. Studies have found conflicting results regarding memory transfer between dissociative identity states. Here, we investigated inter-identity amnesia in individuals with DID using self-relevant, subject specific stimuli, and behavioural and neural measures.MethodsData of 46 matched participants were included; 14 individuals with DID in a trauma-avoidant state, 16 trauma-avoiding DID simulators, and 16 healthy controls. Reaction times and neural activation patterns related to three types of subject specific words were acquired and statistically analysed, namely non-self-relevant trauma-related words (NSt), self-relevant trauma-related words from a trauma-avoidant identity state (St), and trauma-related words from a trauma-related identity state (XSt).ResultsWe found no differences in reaction times between XSt and St words and faster reaction times for XSt over NSt. Reaction times of the diagnosed DID group were the longest. Increased brain activation to XSt words was found in the frontal and parietal regions, while decreased brain activity was found in the anterior cingulate cortex in the diagnosed DID group.DiscussionThe current study reproduces and amalgamates previous behavioural reports as well as brain activation patterns. Our finding of increased cognitive control over self-relevant trauma-related knowledge processing has important clinical implications and calls for the redefinition of “inter-identity amnesia” to “inter-identity avoidance”.

We aimed to investigate transfer of learning, whereby previously acquired skills impact new task learning. While it has been debated whether such transfer may yield positive, negative, or no effects on performance, very little is known about the underlying neural mechanisms, especially concerning the role of inhibitory (GABA) and excitatory (Glu) (measured as Glu + glutamine (Glx)) neurometabolites, as measured by magnetic resonance spectroscopy (MRS). Participants practiced a bimanual coordination task across four days. The Experimental group trained a task variant with the right hand moving faster than the left (Task A) for three days and then switched to the opposite variant (Task B) on Day4. The control group trained Task B across four days. MRS data were collected before, during, and after task performance on Day4 in the somatosensory (S1) and visual (MT/V5) cortex. Results showed that both groups improved performance consistently across three days. On Day4, the Experimental group experienced performance decline due to negative task transfer while the control group continuously improved. GABA and Glx concentrations obtained during task performance showed no significant group-level changes. However, individual Glx levels during task performance correlated with better (less negative) transfer performance. These findings provide a first window into the neurochemical mechanisms underlying task transfer.

Gamma-aminobutyric acid (GABA), the most important inhibitory neurotransmitter in the human brain, has long been considered essential in human behavior in general and learning in particular. GABA concentration can be quantified using magnetic resonance spectroscopy (MRS). Using this technique, numerous studies have reported associations between baseline GABA levels and various human behaviors. However, regional GABA concentration is not fixed and may exhibit rapid modulation as a function of environmental factors. Hence, quantification of GABA levels at several time points during the performance of tasks can provide insights into the dynamics of GABA levels in distinct brain regions. This review reports on findings from studies using repeated measures (n = 41) examining the dynamic modulation of GABA levels in humans in response to various interventions in the perceptual, motor, and cognitive domains to explore associations between GABA modulation and human behavior. GABA levels in a specific brain area may increase or decrease during task performance or as a function of learning, depending on its precise involvement in the process under investigation. Here, we summarize the available evidence and derive two overarching hypotheses regarding the role of GABA modulation in performance and learning. Firstly, training-induced increases in GABA levels appear to be associated with an improved ability to differentiate minor perceptual differences during perceptual learning. This observation gives rise to the ‘GABA increase for better neural distinctiveness hypothesis’. Secondly, converging evidence suggests that reducing GABA levels may play a beneficial role in effectively filtering perceptual noise, enhancing motor learning, and improving performance in visuomotor tasks. Additionally, some studies suggest that the reduction of GABA levels is related to better working memory and successful reinforcement learning. These observations inspire the ‘GABA decrease to boost learning hypothesis’, which states that decreasing neural inhibition through a reduction of GABA in dedicated brain areas facilitates human learning. Additionally, modulation of GABA levels is also observed after short-term physical exercise. Future work should elucidate which specific circumstances induce robust GABA modulation to enhance neuroplasticity and boost performance.

The Compensation Related Utilization of Neural Circuits Hypothesis (CRUNCH) proposes a framework for understanding task-related brain activity changes as a function of healthy aging and task complexity. Specifically, it affords the following predictions: (i) all adult age groups display more brain activation with increases in task complexity, (ii) older adults show more brain activation compared with younger adults at low task complexity levels, and (iii) disproportionately increase brain activation with increased task complexity, but (iv) show smaller (or no) increases in brain activation at the highest complexity levels. To test these hypotheses, performance on a bimanual tracking task at 4 complexity levels and associated brain activation were assessed in 3 age groups (20-40, 40-60, and 60-80 years, n = 99). All age groups showed decreased tracking accuracy and increased brain activation with increased task complexity, with larger performance decrements and activation increases in the older age groups. Older adults exhibited increased brain activation at a lower complexity level, but not the predicted failure to further increase brain activity at the highest complexity level. We conclude that older adults show more brain activation than younger adults and preserve the capacity to deploy increased neural resources as a function of task demand.

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Abstract Introduction Dissociative identity disorder (DID) is characterized by, among others, amnesic episodes and the recurrence of different dissociative identity states. While consistently observed in clinical settings, to our knowledge, no controlled research study has shown the degree to which different identity states report autobiographical knowledge over time. Hence, the current study investigates self‐relevance and emotional intensity ratings of words longitudinally. Methods Data of 46 participants were included: 13 individuals with DID, 11 DID‐simulating actors, and a control group of 22 paired individuals. Individuals with DID and DID simulators participated once in the neutral identity state (NIS) and once in the trauma‐related dissociative identity state (TIS). The control group paired 11 healthy controls with 11 participants with posttraumatic stress disorder (PTSD) as a NIS–TIS pair. Self‐relevance ratings of different word types were collected in a baseline and a follow‐up session, on average 6 weeks apart. A mixed ANOVA design was used to assess the effects of group, session, word type, and dissociative identity state. Results All participants in TIS and individuals with DID in NIS rated self‐relevant trauma‐related words more negatively. In the NIS, the control group rated self‐relevant trauma‐related words as less negative, whereas the ratings of simulating actors were intermediate. There was no group‐dependent longitudinal effect for intensity ratings. Conclusions This study was the first to confirm clinical observations that self‐relevant and emotional processing are different between individuals with DID and controls, but consistent over time. Actors were unable to perfectly simulate DID. The finding that ratings of self‐relevant trauma‐related words differ between subgroups as included in the study is in line with clinical observations.

Aging is associated with changes in the central nervous system and leads to reduced life quality. Here, we investigated the age-related differences in the CNS underlying motor performance deficits using magnetic resonance spectroscopy and diffusion MRI. MRS measured N-acetyl aspartate (NAA), choline (Cho), and creatine (Cr) concentrations in the sensorimotor and occipital cortex, whereas dMRI quantified apparent fiber density (FD) in the same voxels to evaluate white matter microstructural organization. We found that aging was associated with increased reaction time and reduced FD and NAA concentration in the sensorimotor voxel. Both FD and NAA mediated the association between age and reaction time. The NAA concentration was found to mediate the association between age and FD in the sensorimotor voxel. We propose that the age-related decrease in NAA concentration may result in reduced axonal fiber density in the sensorimotor cortex which may ultimately account for the response slowness of older participants.

Synaptic plasticity relies on the balance between excitation and inhibition in the brain. As the primary inhibitory and excitatory neurotransmitters, gamma-aminobutyric acid (GABA) and glutamate (Glu), play critical roles in synaptic plasticity and learning. However, the role of these neurometabolites in motor learning is still unclear. Furthermore, it remains to be investigated which neurometabolite levels from the regions composing the sensorimotor network predict future learning outcome. Here, we studied the role of baseline neurometabolite levels in four task-related brain areas during different stages of motor skill learning under two different feedback (FB) conditions. Fifty-one healthy participants were trained on a bimanual motor task over 5 days while receiving either concurrent augmented visual FB (CA-VFB group, N = 25) or terminal intrinsic visual FB (TA-VFB group, N = 26) of their performance. Additionally, MRS-measured baseline GABA+ (GABA + macromolecules) and Glx (Glu + glutamine) levels were measured in the primary motor cortex (M1), primary somatosensory cortex (S1), dorsolateral prefrontal cortex (DLPFC), and medial temporal cortex (MT/V5). Behaviorally, our results revealed that the CA-VFB group outperformed the TA-VFB group during task performance in the presence of augmented VFB, while the TA-VFB group outperformed the CA-VFB group in the absence of augmented FB. Moreover, baseline M1 GABA+ levels positively predicted and DLPFC GABA+ levels negatively predicted both initial and long-term motor learning progress in the TA-VFB group. In contrast, baseline S1 GABA+ levels positively predicted initial and long-term motor learning progress in the CA-VFB group. Glx levels did not predict learning progress. Together, these findings suggest that baseline GABA+ levels predict motor learning capability, yet depending on the FB training conditions afforded to the participants.

The flexible adjustment of ongoing behavior challenges the nervous system’s dynamic control mechanisms and has shown to be specifically susceptible to age-related decline. Previous work links endogenous gamma-aminobutyric acid (GABA) with behavioral efficiency across perceptual and cognitive domains, with potentially the strongest impact on those behaviors that require a high level of dynamic control. Our analysis integrated behavior and modulation of interhemispheric phase-based connectivity during dynamic motor-state transitions with endogenous GABA concentration in adult human volunteers. We provide converging evidence for age-related differences in the preferred state of endogenous GABA concentration for more flexible behavior. We suggest that the increased interhemispheric connectivity observed in the older participants represents a compensatory neural mechanism caused by phase-entrainment in homotopic motor cortices. This mechanism appears to be most relevant in the presence of a less optimal tuning of the inhibitory tone as observed during healthy aging to uphold the required flexibility of behavioral action. Future work needs to validate the relevance of this interplay between neural connectivity and GABAergic inhibition for other domains of flexible human behavior.

Aging may be associated with motor decline that is attributed to deteriorating white matter microstructure of the corpus callosum (CC), among other brain-related factors. Similar to motor functioning, executive functioning (EF) typically declines during aging, with age-associated changes in EF likewise being linked to altered white matter connectivity in the CC. Given that both motor and executive functions rely on white matter connectivity via the CC, and that bimanual control is thought to rely on EF, the question arises whether EF can at least party account for the proposed link between CC-connectivity and motor control in older adults. To address this, diffusion magnetic resonance imaging data were obtained from 84 older adults. A fiber-specific approach was used to obtain fiber density (FD), fiber cross-section (FC), and a combination of both metrics in eight transcallosal white matter tracts. Motor control was assessed using a bimanual coordination task. EF was determined by a domain-general latent EF-factor extracted from multiple EF tasks, based on a comprehensive test battery. FD of transcallosal prefrontal fibers was associated with cognitive and motor performance. EF partly accounted for the relationship between FD of prefrontal transcallosal pathways and motor control. Our results underscore the multidimensional interrelations between callosal white matter connectivity (especially in prefrontal brain regions), EF across multiple domains, and motor control in the older population. They also highlight the importance of considering EF when investigating brain-motor behavior associations in older adults.

BACKGROUND:Memory function is at the core of the psychopathology of dissociative identity disorder (DID), but little is known about its psychobiological correlates.AIMS:This study aims to investigate whether memory function in DID differs between dissociative identity states.METHOD:Behavioural data and neural activation patterns were assessed in 92 sessions during an n-back working memory task. Participants were people with genuine diagnosed DID (n = 14), DID-simulating controls (n = 16) and a paired control group (post-traumatic stress disorder (n = 16), healthy controls (n = 16)). Both DID groups participated as authentic or simulated neutral and trauma-related identity states. Reaction times and errors of omission were analysed with repeated measures ANOVA. Working memory neural activation (main working memory and linear load) was investigated for effects of identity state, participant group and their interaction.RESULTS:Identity state-dependent behavioural performance and neural activation was found. DID simulators made fewer errors of omission than those with genuine DID. Regarding the prefrontal parietal network, main working memory in the left frontal pole and ventrolateral prefrontal cortex (Brodmann area 44) was activated in all three simulated neutral states, and in trauma-related identity states of DID simulators, but not those with genuine DID or post-traumatic stress disorder; for linear load, trauma-related identity states of those with genuine DID did not engage the parietal regions.CONCLUSIONS:Behavioural performance and neural activation patterns related to working memory in DID are dependent on the dissociative identities involved. The narrowed consciousness of trauma-related identity states, with a proneness to re-experiencing traumatising events, may relate to poorer working memory functioning.

Previous studies aimed to unravel a digit-specific somatotopy in the primary sensorimotor (SM1) cortex. However, it remains unknown whether digit somatotopy is associated with motor preparation and/or motor execution during different types of tasks. We adopted multivariate representational similarity analysis to explore digit activation patterns in response to a finger tapping task (FTT). Sixteen healthy young adults underwent magnetic resonance imaging, and additionally performed an out-of-scanner choice reaction time task (CRTT) to assess digit selection performance. During both the FTT and CRTT, force data of all digits were acquired using force transducers. This allowed us to assess execution-related interference (i.e., digit enslavement; obtained from FTT & CRTT), as well as planning-related interference (i.e., digit selection deficit; obtained from CRTT) and determine their correlation with digit representational similarity scores of SM1. Findings revealed that digit enslavement during FTT was associated with contralateral SM1 representational similarity scores. During the CRTT, digit enslavement of both hands was also associated with representational similarity scores of the contralateral SM1. In addition, right hand digit selection performance was associated with representational similarity scores of left S1. In conclusion, we demonstrate a cortical origin of digit enslavement, and uniquely reveal that digit selection is associated with digit representations in primary somatosensory cortex (S1). Significance statement In current systems neuroscience, it is of critical importance to understand the relationship between brain function and behavioral outcome. With the present work, we contribute significantly to this understanding by uniquely assessing how digit representations in the sensorimotor cortex are associated with planning- and execution-related digit interference during a continuous finger tapping and a choice reaction time task. We observe that digit enslavement (i.e., execution-related interference) finds its origin in contralateral digit representations of SM1, and that deficits in digit selection (i.e., planning-related interference) in the right hand during a choice reaction time task are associated with more overlapping digit representations in left S1. This knowledge sheds new light on the functional contribution of the sensorimotor cortex to everyday motor skills.