Effect of transcranial direct current stimulation on psychomotor skill acquisition during laparoscopic training: a randomized controlled trial

Abstract

Background

Acquisition of laparoscopic psychomotor skills is essential for safe minimally invasive surgery but is associated with a steep learning curve. Simulation-based training improves proficiency; however, additional strategies to accelerate skill acquisition are sought. Transcranial direct current stimulation (tDCS) has been shown to facilitate motor learning, but its effect on laparoscopic training remains uncertain.

Methods

In this prospective, sham-controlled trial, 33 medical students without prior laparoscopic experience were allocated to active tDCS (n = 16) or sham stimulation (n = 17) during laparoscopic simulation training. Stimulation was delivered using the Halo Sport system (1.4 mA, 20 min) over bilateral primary motor cortices. Baseline psychomotor abilities were assessed using the Vienna Test System (Motor Performance Series, 2HAND, and 3D spatial ability tests). Laparoscopic skills were evaluated using the Laparoscopic Skills Testing and Training (LASTT) model, including camera navigation (CN), hand–eye coordination (HE), and bimanual coordination (Bi), on days 1, 3, 5, and 7. Group differences in final performance (day 7) were analyzed using linear models and ANCOVA, adjusting for baseline performance and prespecified covariates.

Results

Both groups demonstrated significant improvement across all laparoscopic tasks over time (all p < 0.001). Active tDCS was independently associated with higher final bimanual coordination performance compared with sham stimulation (adjusted ANCOVA: F (1,13) = 14.92, p = 0.002). No independent effect of tDCS was observed for camera navigation (p = 0.581) or hand–eye coordination (p = 0.439). Baseline visuospatial ability (3D test) was an independent predictor of final performance in camera navigation and hand–eye coordination (both p < 0.01). Positive correlations were found between 3D scores and CN (r = 0.397) and HE (r = 0.390), as well as between 2HAND and HE (r = 0.341).

Conclusions

Bihemispheric tDCS applied during laparoscopic simulation selectively enhanced acquisition of bimanual coordination, while performance in camera navigation and hand–eye coordination was primarily determined by baseline visuospatial ability. These findings support a task-specific role for neuromodulation as an adjunct to simulation-based laparoscopic training and highlight the importance of visuospatial profiling for personalized training strategies.

Minimally invasive surgery has revolutionized operative gynecology by reducing perioperative complications, shortening hospital stays, and improving cosmetic outcomes compared to open procedures. Despite clear advantages, the global adoption of laparoscopic hysterectomy remains heterogeneous, with leading centers and countries achieving rates approaching 90%, while many regions still report substantially lower utilization [1]. One major barrier is the steep learning curve associated with laparoscopic psychomotor skills, which differ fundamentally from those required in open surgery. Based on the standards developed by the European Academy of Gynaecological Surgery (EAGS), three fundamental psychomotor skills were identified as essential for laparoscopic proficiency: camera navigation (CN), hand-eye coordination (HE), and bimanual coordination (Bi). These specific skills form the core of the validated Laparoscopic Skills Testing and Training (LASTT) model, which is a key component of the GESEA (Gynaecological Endoscopic Surgical Education and Assessment) program. This framework recognizes the LASTT model as a mandatory tool for both students and novices to master fundamental "building blocks" in a simulation setting [2]. Proficiency in these tasks is a prerequisite for obtaining standardized diplomas, such as the "Bachelor in Endoscopy" or the "MIGS" (Minimal Invasive Gynecological Surgeon) certificate. Such structural training at an early stage of medical education provides an objective measure of readiness for future surgical residents, ensuring that the essential psychomotor prerequisites for safe and efficient performance are met before entering the operating room and become a central component of structured curricula recommended by international societies ESGE (European Society for Gynaecological Endoscopy), EAES (European Association for Endoscopic Surgery) and AAGL (Advancing Minimally Invasive Gynecology Worldwide) [3].

In recent years, non-invasive neurostimulation has emerged as a potential enhancer of motor learning. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that applies low-intensity direct current to modulate cortical excitability and enhance neuroplasticity. Findings from neurorehabilitation and motor learning studies suggests that tDCS can improve acquisition and consolidation of fine motor skills. While its application in surgical training is novel, preliminary studies in neurosurgical simulation and motor tasks indicate potential benefits [4, 5]. One recent randomized trial found that active bilateral M1-tDCS significantly accelerated skill acquisition on a laparoscopic peg-transfer task compared to sham stimulation. However, beyond such preliminary work, robust data are scarce [6].

The present study aimed to investigate the effect of anodal–cathodal tDCS applied over bilateral motor cortices during laparoscopic training on the acquisition of basic psychomotor skills—specifically Camera Navigation (CN), Hand-Eye coordination (HE), and Bimanual (Bi) coordination. Medical students represent an ideal target population for investigating early-stage neurostimulation, as their lack of prior surgical exposure provides a critical "clean slate," thereby eliminating the confounding effects of heterogeneous baseline experience often observed in surgical residents.

Additionally, we explored whether baseline psychomotor abilities—assessed using standardized Vienna Test System (VTS) tasks—predict performance in laparoscopic exercises. This objective profiling was crucial to eliminate and control for potential baseline psychomotor variances among students. Such differences frequently arise from diverse individual backgrounds and everyday activities, such as playing musical instruments, participating in coordination-intensive sports, or video gaming. By evaluating fine motor performance, bimanual coordination, and 3D spatial ability through the VTS, the participants inherent cognitive and psychomotor readiness was precisely quantified prior to training.

This approach directly aligns with international training standards, such as the European GESEA (Gynecological Endoscopic Surgical Education and Assessment) framework, which mandates that fundamental laparoscopic psychomotor skills should be mastered at the pre-clinical or undergraduate level (e.g., for the Bachelor in Endoscopy) in risk-free simulation environments. We hypothesized that tDCS would enhance learning outcomes, particularly for complex bimanual tasks, and that baseline spatial ability would correlate with laparoscopic performance.

Materials and methods

The study was designed and reported in accordance with the CONSORT 2010 (Consolidated Standards of Reporting Trials) guidelines for randomized controlled trials (Fig. 1). This prospective, randomized controlled trial (RCT) with a parallel-group design was conducted at the Lower Silesian Oncology, Pulmonology, and Hematology Center in Wrocław, Poland, between 2019 and 2020. The study protocol was approved by the Bioethics Committee of the Wroclaw Medical University (Approval No. KB-423/2019), and all participants provided written informed consent prior to enrollment. Thirty-three medical students (20 women and 13 men) without prior laparoscopic experience were recruited. The inclusion criterion was no previous exposure to laparoscopic training or operating room procedures. Exclusion criteria included a history of psychiatric or neurological disorders, head trauma, brain tumor resection, cranial implants, use of neuroactive substances, or congenital/acquired upper limb motor dysfunctions.

Fig. 1.

CONSORT 2010 flow diagram of participant progress through the phases of the randomized controlled trial

Participants were randomly allocated to two groups: Group A (experimental, n = 16), which received transcranial direct current stimulation (tDCS) during training, and Group B (control, n = 17), which underwent sham stimulation. Randomization was performed using a randomly generated assignment sequence by the principal investigator. Allocation concealment was maintained, and both participants and the outcome assessor were blinded to the group assignment. The stimulation device was activated remotely in both groups to maintain blinding.

Stimulation was delivered using the Halo Sport neuromodulation headset (Halo Neuroscience, San Francisco, USA). Direct current of 1.4 mA was applied for 20 min with a 30-s ramp-up and ramp-down. Three rectangular electrodes (6.4 × 4.4 cm; contact area 28 cm²), soaked in 0.9% sodium chloride saline (Polpharma, Poland), were positioned according to the International 10–20 electroencephalography (EEG) system: the anode over C3 and the cathode over C4. Sham stimulation used an identical setup without current flow. No adverse events were reported.

Laparoscopic psychomotor skills were assessed using the Laparoscopic Skills Testing and Training (LASTT) model developed by the European Society for Gynaecological Endoscopy (ESGE). Exercises were performed in a Szabo trainer box equipped with a 10-mm 0° and 30° laparoscope, ClickLine Kelly and Manhes monopolar forceps (Karl Storz, Tuttlingen, Germany), and a Karl Storz Telepack NTSC video system. Three standardized tasks were evaluated: camera navigation (CN), hand–eye coordination (HE), and bimanual coordination (Bi). Each task was repeated three times on days 1, 3, and 5, with a final assessment on day 7.

Baseline psychomotor abilities were measured using the Vienna Test System (VTS; Schuhfried GmbH, Austria), including the Motor Performance Series (MLS) Test S1 (stability, linear tracking, targeting, tapping), the 2HAND Test (bimanual coordination), and the 3D Spatial Test (visual–spatial ability). The primary outcome was performance scores (T-score) for CN, HE, and Bi tasks on day 7. Secondary outcomes included correlations between baseline psychomotor tests and laparoscopic performance.

Normality was assessed using the Kolmogorov–Smirnov test with Lilliefors correction and the Shapiro–Wilk test. Parametric tests (independent and paired t-tests) or non-parametric tests (Mann–Whitney U, Friedman ANOVA) were applied as appropriate. Analysis of covariance (ANCOVA) controlled for confounders such as sex and baseline skills. Statistical significance was set at p < 0.05.

Results

Thirty-three medical students were randomized to active transcranial direct current stimulation (tDCS; Group A, n = 16) or sham (Group B, n = 17). The groups showed similar sex distribution, but left-hand dominance was more frequent in the tDCS group (25.0% vs. 0.0%; p = 0.044) (Table 1). Due to this imbalance, psychomotor outcomes were summarized by dominant versus non-dominant hand performance where relevant.

Table 1.

Baseline characteristics (randomized population)

Variable	Group A (n = 16)	Group B (n = 17)	p
Sex — female, n (%)	8 (50.0)	12 (70.6)	0.394
Hand dominance — left, n (%)	4 (25.0)	0 (0.0)	0.044
2HAND — mean track time, T-score (mean ± SD)	42.9 ± 8.8	44.6 ± 6.4	0.511
3D — visual–spatial, T-score (mean ± SD)	55.8 ± 6.5	55.9 ± 6.6	0.955

Baseline psychomotor performance assessed with the Vienna Test System (VTS) did not differ significantly between the experimental group (tDCS stimulation) and the control group. Both groups demonstrated comparable scores in bimanual coordination (2HAND test), visuospatial ability (3D test), and motor performance of dominant and non-dominant hands (MLS battery) (p > 0.05). (Table 2).

Table 2.

Baseline characteristics of psychomotor performance in experimental and control groups

Variable	Group A (Experimental)	Group B (Control)	p
2HAND test – bimanual coordination
MT 2HAND – mean passage time (s)	29.8 ± 11.0	25.8 ± 7.6	0.228
MT 2HAND (%)	30.1 ± 25.1	32.9 ± 19.2	0.718
MT 2HAND (T-score)	42.9 ± 8.8	44.6 ± 6.4	0.511
3D Test – visuospatial ability
Correct answers (raw score)	17.4 ± 3.3	17.5 ± 3.3	0.977
Incorrect answers (raw score)	4.88 ± 3.54	4.18 ± 3.43	0.569
Percentage correct (%)	68.7 ± 20.7	68.2 ± 20.7	0.944
T-score	55.8 ± 6.5	55.9 ± 6.6	0.955
MLS – motor performance (dominant hand)
Targeting (hits)	19.1 ± 2.5	19.3 ± 0.9	0.796
Targeting time (s)	6.7 ± 1.2	6.6 ± 1.0	0.101
Tapping (hits)	201 ± 32	210 ± 20	0.376

(Values are presented as mean ± SD; p-values from Student’s t-test)

Similarly, performance on the laparoscopic skills testing and training (LASTT) model on day 1 did not differ significantly between groups for camera navigation (CN), hand–eye coordination (HE), or bimanual coordination (Bi) (Table 3).

Table 3.

LASTT baseline performance (day 1; T-scores)

Task	Group A (n = 16)	Group B (n = 17)	p
Camera navigation (CN)	18.7 ± 17.2	24.1 ± 18.8	0.140
Hand–eye coordination (HE)	22.9 ± 19.5	25.0 ± 22.9	0.628
Bimanual coordination (Bi)	28.3 ± 19.1	25.4 ± 16.6	0.416

The primary analysis demonstrated that tDCS significantly improved bimanual coordination after training. In linear models, the intervention was associated with a higher final Bi score on day 7 (Bi T4; b = 16.72; p = 0.020) (Table 4). This finding was corroborated by an analysis of covariance showing a significant group effect for Bi T4 after adjustment for prespecified covariates and intermediate training scores (F(1,13) = 14.92; p = 0.002) (Table 5), and by a non-parametric between-group comparison at day 7 (Mann–Whitney U, Z = 2.438; p = 0.015) (Table 6). No independent effect of tDCS was observed for camera navigation or hand–eye coordination (CN T4: p = 0.581; HE T4: p = 0.439) (Table 4).

Table 4.

Univariable predictors of final performance (T4; linear models)

Predictor	CN (b)	CN (p)	HE (b)	HE (p)	Bi (b)	Bi (p)
tDCS (yes vs. no)	3.37	0.581	−4.88	0.439	16.72	0.020
Sex (female = 1)	−15.6	0.008	−1.08	0.868	−20.1	0.005
3D (T-score)	1.35	0.003	1.23	0.009	0.31	0.599
CN baseline (T-score)	0.65	< 0.001	0.40	0.018	0.41	0.045
HE baseline (T-score)	0.30	0.033	0.34	0.019	0.35	0.041

Table 5.

ANCOVA for Bi T4 (adjusted effects)

Effect	F	df	p
Group (tDCS vs. sham)	14.92	1,13	0.002
Bi day 5 (T-score)	13.10	1,13	0.003
MS-B (dominant hand, T-score)	8.24	1,13	0.013
MS-B-CZ (dominant hand, error-time T-score)	14.70	1,13	0.002
Sex	1.31	1,13	0.273

The bold text in this table is used to highlight the primary outcome and main effect of interest (Group: tDCS vs. sham)

Table 6.

Mann–Whitney U (T-scores; median [Q1–Q3])

Task	Day	Group A	Group B	p
CN	T1	13 [7–25]	24 [11–31]	0.377
CN	T2	46 [25–56]	40 [20–58]	0.986
CN	T3	63 [46–82]	68 [44–95]	0.871
CN	T4	82 [78–95]	86 [58–95]	0.855
HE	T1	19 [7–28]	18 [4–35]	0.914
HE	T2	54 [31–78]	55 [33–70]	0.900
HE	T3	74 [44–90]	66 [61–82]	0.899
HE	T4	78 [61–94]	90 [78–95]	0.337
Bi	T1	27 [14–37]	24 [13–35]	0.732
Bi	T2	54 [44–69]	46 [35–61]	0.367
Bi	T3	76 [66–83]	78 [52–84]	0.971
Bi	T4	89 [80–93]	74 [52–81]	0.015

The bold value in this table indicates a statistically significant difference between the groups (p 0.05)

Across the training period (days 1, 3, 5, and 7), both groups exhibited significant within-group improvement for CN, HE, and Bi (Friedman tests, all p < 0.001), consistent with a robust learning effect (Figs. 2, 3 and 4).

Fig. 2.

Learning curves for Camera Navigation (CN) performance across training days, measured by T-Score for thetDCS and Sham groups

Fig. 3.

Learning curves for Hand–Eye Coordination (HE) performance across training days, measured by T-Score forthe tDCS and Sham groups

Fig. 4.

Learning curves for Bimanual Coordination (BI) performance across training days, measured by T-Score forthe tDCS and Sham groups

Visual–spatial ability measured by the 3D test at baseline was an independent predictor of final performance in both CN and HE (CN T4: p = 0.003; HE T4: p = 0.009) (Table 4). Consistent with this, baseline correlations were positive between 3D scores and CN (r = 0.397) and between 3D scores and HE (r = 0.390) (Table 7). In addition, bimanual coordination skills on the 2HAND test correlated positively with HE (r = 0.341) (Table 7). Sex was associated with final task outcomes: male participants performed significantly better than females in CN (p = 0.008) and Bi (p = 0.005), but not in HE (p = 0.868) (Table 4). No adverse events were reported during the study.

Table 7.

Baseline correlations (T1; Pearson r)

Predictor (VTS)	CN	HE	Bi
3D (visual–spatial, T-score)	0.397	0.390	0.298
2HAND — mean track time (T-score)	0.223	0.341	−0.017
ME 2HAND (T-score)	0.138	0.263	0.309
MC-CZ (aiming time, dominant hand; T-score)	−0.194	−0.184	−0.223

Discussion

Principal findings

In this randomized, sham-controlled training study, transcranial direct current stimulation (tDCS) over bilateral primary motor cortices yielded a selective improvement in bimanual coordination, with no independent effect on camera navigation or hand–eye coordination. The bimanual effect was consistent across analytic approaches (linear models, ANCOVA, and non-parametric testing), whereas performance in camera navigation and hand–eye tasks was primarily explained by visual–spatial ability assessed at baseline (3D test) and by initial task performance. A robust within-group learning effect was present for all tasks. Additionally, male sex was associated with better final outcomes in camera navigation and bimanual coordination. No adverse events were reported.

Mechanistic plausibility: why tDCS benefited bimanual coordination

The selective benefit of tDCS on bimanual skills aligns with mechanistic models in which bihemispheric stimulation modulates interhemispheric interactions of the motor system—reducing transcallosal inhibition from the dominant hemisphere and facilitating the non-dominant effector. Foundational work has shown polarity-dependent shifts in corticospinal excitability with tDCS (anodal depolarization, cathodal hyperpolarization), providing a credible substrate for motor learning gains [7–9]. In healthy individuals, dual-hemisphere tDCS can augment motor sequence learning and effector-independent synergies more strongly than uni-hemisphere protocols, plausibly by improving bilateral coordination needed for simultaneous instrument manipulation in laparoscopy [10–12]. These mechanisms dovetail with neuroimaging evidence that bimanual coordination relies on dynamic intra- and interhemispheric coupling across M1 and association networks [13–15]. The present improvement in Bi after tDCS, coupled with no adverse events, supports tDCS as a feasible adjunct to simulation-based laparoscopy training for bimanual skills. Furthermore, prior work by Reis et al. demonstrated that non-invasive cortical stimulation could enhance motor skill acquisition over multiple days, reinforcing the plausibility of our findings [16].

Why camera navigation and hand–eye coordination did not improve with tDCS

Camera navigation (CN) and hand–eye coordination (HE) improved over time (training effect), yet tDCS had no independent impact once baseline covariates were considered. This likely reflects the cognitive–visuospatial dominance of these tasks: surgeons must transform a 2D image into an internal 3D representation under changing viewing angles and scopes (0°/30°), and map vision into precise tool movements. Prior work shows that visual–spatial ability and mental rotation robustly predict laparoscopic performance and suture skill acquisition; thus, variance in CN and HE is better captured by visuospatial metrics than by primary motor excitability alone [17–20]. Our data concur—3D scores independently predicted CN and HE outcomes, and baseline CN/HE performance accounted for large portions of variance at day 7. Taken together, the absence of a tDCS effect on CN/HE is coherent with task demands: modulation at M1 may be insufficient to overcome perceptual–cognitive bottlenecks, which likely require targeted visuospatial training or alternative neuromodulatory targets (e.g., parietal/dorsal visual stream).

Training effects and educational context

Both groups demonstrated significant day-to-day improvement across CN, HE, and Bi, confirming the value of structured simulation curricula. Prior RCTs and multi-center studies show that standardized simulation plus deliberate practice accelerates skill acquisition and transfers to better intraoperative performance compared with unstructured training, especially in laparoscopy [21, 22]. The present findings extend this by integrating objective psychomotor profiling (VTS battery: 2HAND, 3D, MLS) and demonstrating that baseline visuospatial and coordination measures can forecast learning trajectories on specific laparoscopic tasks. These supports incorporating competency screening (e.g., 3D/2HAND) to personalize training intensity and content—e.g., enhancing visuospatial drills for CN/HE, while coupling bimanual tasks with neuromodulation when appropriate. Additionally, the LASTT model used in this study has been validated as a reliable tool for laparoscopic psychomotor skills assessment, further supporting the robustness of our training approach [2].

Strengths and limitations

Strengths include a randomized, sham-controlled design with blinding, standardized LASTT tasks, integration of objective baseline psychomotor assessments, and triangulation of effects via parametric, non-parametric, and ANCOVA models. The selective tDCS effect on Bi was consistent and clinically interpretable in the context of laparoscopy. Several limitations must also be acknowledged. First, the study is characterized by a relatively small sample size, a single-center setting, and a baseline imbalance in hand dominance, with a higher frequency of left-handed participants in the active tDCS arm. Second, the outcomes were restricted to simulator-based metrics rather than real-world intraoperative endpoints, such as clinical error rates or time to proficiency in the operating room. Third, some positional statistics for the final assessment (day 7) could not be fully reconstructed for all tasks, which constrained boxplot completeness.

Finally, a notable limitation is the short follow-up period, with the final assessment conducted at day 7, which prevents the direct evaluation of long-term skill retention within this specific cohort. In the context of motor learning, demonstrating the long-term persistence of acquired skills is essential. Seminal longitudinal work by Reis et al. (2009) has shown that tDCS facilitates motor skill acquisition over multiple days primarily by enhancing offline consolidation [16, 23, 24]. In complex psychomotor tasks, this neuromodulatory enhancement has been associated with long-term plasticity-related mechanisms, potentially contributing to improved retention of the acquired motor memory trace for extended periods after the initial training intervention. Although our 7-day protocol captured the accelerated acquisition phase, future multi-center trials with multi-week or multi-month retention testing are strictly warranted to verify if the tDCS-mediated gains in bimanual coordination translate into such permanent baseline shifts within structured surgical curricula.

Future directions

Given the task-specific benefits, future work should (i) evaluate bihemispheric tDCS as an adjunct to bimanual modules across different simulators and curricula; (ii) test alternative targets (e.g., posterior parietal cortex or premotor cortex) for tasks dominated by visuospatial transformation (CN/HE); (iii) integrate personalized training based on baseline 3D/2HAND profiles; and (iv) examine dose–response (current intensity, session number, montage) and retention at multi-week/month horizons. Mechanistic studies using fMRI/MEG and network analyses could clarify whether benefits arise from reduced interhemispheric inhibition, enhanced bilateral synergy representations, or attentional modulation. Finally, incorporating robotic platforms and complex suturing may test whether bihemispheric tDCS generalizes to higher-order bimanual tasks central to minimally invasive surgery [22, 25–27]. Additionally, clinical studies are needed to determine whether tDCS-augmented training translates into improved operative performance and reduced intraoperative errors in real-world surgical settings.

Conclusions

Bihemispheric tDCS during laparoscopy simulation selectively improved bimanual coordination, while camera navigation and hand–eye coordination remained primarily determined by baseline visual–spatial ability and initial performance. These results support the use of targeted neuromodulation to augment training in complex bimanual skills and highlight the value of visuospatial assessment in tailoring educational strategies for camera navigation and hand–eye tasks. The overall learning gains across days reaffirm the importance of structured, competency-based simulation curricula in minimally invasive surgery education.

Author contributions

Conceptualization: P. Lepka. Methodology: P. Lepka and D. Szcześniak. Formal analysis: P. Lepka. Investigation: P. Lepka, Z. Sikora, and D. Szcześniak. Writing—original draft: P. Lepka. Writing—review and editing: All authors. Supervision: D. Szcześniak and R. Matkowski. All authors have reviewed and approved the final version and agree to be accountable for all aspects of the work.

Funding

This research was financed through a statutory subsidy by the Ministry of Health as part of the Department of Oncology Wroclaw Medical University research grant SUBZ.C280.26.041 (record number in the Simple System).

Data availability

The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Disclosures

Piotr Lepka, Dorota Szcześniak, Zofia Sikora, Rafał Matkowski have no conflicts of interest or financial ties to disclose.

Ethical approval

The study protocol was approved by the Bioethics Committee at Wroclaw Medical University (approval No. KB-423/2019). All procedures were conducted in accordance with the Declaration of Helsinki and institutional guidelines.

Consent to participate

All participants provided written informed consent prior to enrollment and study procedures.

Consent for publication

No individually identifiable data (including images) are included in this manuscript. Consent for publication of anonymized aggregate data was obtained at enrollment.