The role of dorsal premotor cortex in mental rotation: A transcranial magnetic stimulation study

Anatomical predictors of mental rotation with bodily and non-bodily stimuli: A lesion-symptom study

Mental rotation (MR) is widely regarded as a quintessential example of an embodied cognitive process. This viewpoint stems from the functional parallels between MR and the physical rotation of tangible objects, as well as participants' inclination to employ motor-based strategies when tackling MR tasks involving bodily stimuli. These commonalities imply that MR may depend on brain regions crucial for the planning and execution of motor programs. However, there is disagreement regarding the anatomy of MR between findings from functional imaging and lesion studies involving brain-injured patients. The former indicate the involvement of the right-hemispheric parietal cortex, while the latter underscore the significance of posterior areas in the left hemisphere. In this study, we aimed to discern the neural underpinnings of MR using lesion-symptom mapping (LSM) for both bodily (hands) and non-bodily (letters) stimuli. Behavioral results from the two MR tasks revealed impaired MR of bodily stimuli in patients with left hemisphere damage. LSM results pinpointed the left primary motor and somatosensory cortices, along with the superior parietal lobule, as the anatomical substrates of MR for both bodily and non-bodily stimuli. Furthermore, damage to the left angular gyrus, supramarginal gyrus, supplementary motor area, and retrosplenial cortex was associated with MR of non-bodily stimuli. These findings support the causal involvement of the left hemisphere in MR and underscore the existence of a common anatomical substrate in brain regions pertinent to motor planning and execution.

How embodied is cognition? fMRI and behavioral evidence for common neural resources underlying motor planning and mental rotation of bodily stimuli

Functional neuroimaging shows that dorsal frontoparietal regions exhibit conjoint activity during various motor and cognitive tasks. However, it is unclear whether these regions serve several, computationally independent functions, or underlie a motor "core process" that is reused to serve higher-order functions. We hypothesized that mental rotation capacity relies on a phylogenetically older motor process that is rooted within these areas. This hypothesis entails that neural and cognitive resources recruited during motor planning predict performance in seemingly unrelated mental rotation tasks. To test this hypothesis, we first identified brain regions associated with motor planning by measuring functional activations to internally-triggered vs externally-triggered finger presses in 30 healthy participants. Internally-triggered finger presses yielded significant activations in parietal, premotor, and occipitotemporal regions. We then asked participants to perform two mental rotation tasks outside the scanner, consisting of hands or letters as stimuli. Parietal and premotor activations were significant predictors of individual reaction times when mental rotation involved hands. We found no association between motor planning and performance in mental rotation of letters. Our results indicate that neural resources in parietal and premotor cortex recruited during motor planning also contribute to mental rotation of bodily stimuli, suggesting a common core component underlying both capacities.

Transcranial Magnetic Stimulation of the Dorsolateral Prefrontal Cortex Increases Posterior Theta Rhythm and Reduces Latency of Motor Imagery

Experiments show activation of the left dorsolateral prefrontal cortex (DLPFC) in motor imagery (MI) tasks, but its functional role requires further investigation. Here, we address this issue by applying repetitive transcranial magnetic stimulation (rTMS) to the left DLPFC and evaluating its effect on brain activity and the latency of MI response. This is a randomized, sham-controlled EEG study. Participants were randomly assigned to receive sham (15 subjects) or real high-frequency rTMS (15 subjects). We performed EEG sensor-level, source-level, and connectivity analyses to evaluate the rTMS effects. We revealed that excitatory stimulation of the left DLPFC increases theta-band power in the right precuneus (PrecuneusR) via the functional connectivity between them. The precuneus theta-band power negatively correlates with the latency of the MI response, so the rTMS speeds up the responses in 50% of participants. We suppose that posterior theta-band power reflects attention modulation of sensory processing; therefore, high power may indicate attentive processing and cause faster responses.

Imaging the Spin: Disentangling the Core Processes Underlying Mental Rotation by Network Mapping of Data From Meta-analysis

Research on the mental rotation task has sparked debate regarding the specific processes that underly the capability of humans to mentally rotate objects. The spread of reported brain activations suggests that mental rotation is subserved by a neural network circle. However, no common network has yet been found that uncovers the crucial processes underlying this ability. We aimed to identify the common network crucial for mental rotation by coordinate-based network mapping of previous neuroimaging findings in mental rotation. A meta-analysis revealed 710 peak activation coordinates from 42 fMRI studies in mental rotation, which include a total 844 participants. The coordinates were mapped to a normative functional connectome (n = 1000) to identify a network of connected regions. To account for experimental factors, we examined this network against two control tasks, action imitation and symbolic number processing. A common and crucial network for mental rotation, centring on dorsal premotor, superior parietal and inferior temporal lobes was revealed. This network, separated from other experimental aspects, suggests that the crucial processes underlying mental rotation are motor rotation, visuospatial processing, and higher order visual object recognition.

Functional topologies of spatial cognition predict cognitive and motor progression in Parkinson’s

Background

Spatial cognition deteriorates in Parkinson’s disease (PD), but the neural substrates are not understood, despite the risk for future dementia. It is also unclear whether deteriorating spatial cognition relates to changes in other cognitive domains or contributes to motor dysfunction.

Objective

This study aimed to identify functional connectivity abnormalities in cognitively normal PD (PDCN) in regions that support spatial cognition to determine their relationship to interfacing cognitive functions and motor disability, and to determine if they predict cognitive and motor progression 2 years later in a PDCN subsample.

Methods

Sixty-three PDCN and 43 controls underwent functional MRI while judging whether pictures, rotated at various angles, depicted the left or right hand. The task activates systems that respond to increases in rotation angle, a proxy for visuospatial difficulty. Angle-modulated functional connectivity was analyzed for frontal cortex, posterior cortex, and basal ganglia regions.

Results

Two aberrant connectivity patterns were found in PDCN, which were condensed into principal components that characterized the strength and topology of angle-modulated connectivity. One topology related to a marked failure to amplify frontal, posterior, and basal ganglia connectivity with other brain areas as visuospatial demands increased, unlike the control group (control features). Another topology related to functional reorganization whereby regional connectivity was strengthened with brain areas not recruited by the control group (PDCN features). Functional topologies correlated with diverse cognitive domains at baseline, underscoring their influences on spatial cognition. In PDCN, expression of topologies that were control features predicted greater cognitive progression longitudinally, suggesting inefficient communications within circuitry normally recruited to handle spatial demands. Conversely, stronger expression of topologies that were PDCN features predicted less longitudinal cognitive decline, suggesting functional reorganization was compensatory. Parieto-occipital topologies (control features) had different prognostic implications for longitudinal changes in motor disability. Expression of one topology predicted less motor decline, whereas expression of another predicted increased postural instability and gait disturbance (PIGD) feature severity. Concurrently, greater longitudinal decline in spatial cognition predicted greater motor and PIGD feature progression, suggesting deterioration in shared substrates.

Conclusion

These novel discoveries elucidate functional mechanisms of visuospatial cognition in PDCN, which foreshadow future cognitive and motor disability.

From Action to Cognition: Neural Reuse, Network Theory and the Emergence of Higher Cognitive Functions

The aim of this article is to discuss the logic and assumptions behind the concept of neural reuse, to explore its biological advantages and to discuss the implications for the cognition of a brain that reuses existing circuits and resources. We first address the requirements that must be fulfilled for neural reuse to be a biologically plausible mechanism. Neural reuse theories generally take a developmental approach and model the brain as a dynamic system composed of highly flexible neural networks. They often argue against domain-specificity and for a distributed, embodied representation of knowledge, which sets them apart from modular theories of mental processes. We provide an example of reuse by proposing how a phylogenetically more modern mental capacity (mental rotation) may appear through the reuse and recombination of existing resources from an older capacity (motor planning). We conclude by putting arguments into context regarding functional modularity, embodied representation, and the current ontology of mental processes.

Non-invasive brain stimulation in modulation of mental rotation ability: A systematic review and meta-analysis

Mental rotation, the ability to manipulate mental images, is an important function in human cognition. This systematic review and meta-analysis investigates the potential of non-invasive brain stimulation in modulation of this component of visuo-spatial perception. The PubMed database was reviewed prior to 31 September 2020 on randomized controlled trials investigating the effects of repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and transcranial alternating current stimulation (tACS) on the mental rotation ability in healthy persons. A total of 17 studies (including 485 subjects) matched our inclusion criteria. Within their scope, overall, 46 sham-controlled experiments were performed. Methodology and results of each experiment are presented in a meta-analysis. The data show a large variety of methods and effects. The influence of (1) stimulation-technique (tDCS, tACS, and rTMS), (2) stimulation protocol (anodal, cathodal, bilateral tDCS, tACS, high-frequency rTMS, low-frequency rTMS, paired pulse rTMS, and theta burst stimulation), (3) stimulation timing (preconditioning and simultaneous), (4) stimulation location (left, right hemisphere, frontal, and parietal area), and (5) stimulus type (bodily and non-bodily) is discussed. The data indicate a beneficial effect of anodal tDCS and of tACS and no effect of cathodal tDCS on the mental rotation ability. Bilateral tDCS protocols both improved and worsened the parameters assessed. The small effect sizes obtained in mostly rTMS experiments require cautious interpretation.

Neurophysiology of embodied mental rotation: Event-related potentials in a mental rotation task with human bodies as compared to alphanumeric stimuli

The present study examines if the neural signature of information processing in mental rotation tasks is moderated by stimulus characteristics (e.g., body-related vs. non-body-related stimuli). In the present experiment, stimulus sets of human figures (back view; left vs. right arm abduction) and alphanumeric characters ('R'; normal vs. mirrored view) were scrutinized with event-related potentials (ERPs) in the electroencephalography (EEG). Participants had to judge parity between an upright (0° orientation) and a comparison stimulus (stimulus disparity; 0°, 45°, 90°, 135° or 180°). There was a main effect of stimulus disparity for the behavioural (response time and error rates), as well as for the neural data (rotation-related negativity, RRN). The interaction of stimulus disparity and stimulus type was significant for the RRN, but not for the response time. Lower RRN amplitudes for letters indicate a more pronounced use of alternative processes (e.g., memory retrieval), which seems to be reflected in higher N350 amplitudes. Moreover, the increase of the RRN amplitude and the increase in response time as a function of disparity were positively correlated. Task differences were evident for several ERP components (i.e., N150, P150 and N250), being independent of disparity, which might reflect differences in early and late object cognition prior to the mental rotation process itself. This might be associated with the task-dependent activation of embodied cognition processes in mental rotation tasks.

Association between cognitive quotient test score and hippocampal volume: a novel, rapid application-based screening tool

We aimed to develop a brief, preclinical test to screen the reduced hippocampal volume that is a marker of early dementia [Cognitive Quotient (CQ) test]. We performed an observational study of adult subjects who underwent brain MRI in seven institutions from February 2018 to May 2019. The CQ test consists of five components: (1) digits forward, (2) digits backward, (3) Stroop test, (4) simple calculation, and (5) mental rotation. The primary outcome measure was hippocampal volume. We separated the data into derivation (n = 322) and validation cohorts (n = 96). In the derivation cohort, we built two scoring systems using the results of CQ test (model 1 and 2). In the validation cohort, we validated the correlation of the scoring systems with hippocampal volume. In the derivation cohort, there was a moderate correlation between the scoring systems and hippocampal volume [e.g., correlation coefficient = 0.62 in model 1 (95% CI 0.44–0.75)]. Likewise, in the validation cohort, there was a moderate correlation between the scoring systems and hippocampal volume [e.g., correlation coefficient = 0.54 in model 2 (95% CI 0.38–0.67)]. In this analysis of 418 participants, the score of newly developed CQ test was correlated with hippocampal volume.

A neuroimaging comparative study of changes in a cellist's brain when playing contemporary and Baroque styles

The emergence of different styles of Contemporary concert music in the 20th century led to a marked modification of the foundations built on previous styles. This work investigates whether these modifications, which include procedures and technical resources different to those used in the interpretation of previous musical styles, require different encephalic controls to those used in tonal music and if the experience of the musician in these styles influences them. Functional magnetic resonance images of encephalic regions from 13 professional cellists while interpreting Baroque and Contemporary excerpts inside an MRI scanner were acquired. Activation and connectivity encephalic maps show common cortical motor and sensorial regions (Precentral, Postcentral and Supramarginal Gyri) in both interpretation styles, but with different hemispheric intensity levels. However, certain auditory and motor regions only activate during Baroque. Connectivity maps show some exclusive seed-regions; thus, the Heschl's and Superior Frontal Gyri, Planum-Temporal and Caudate appear as prominent seeds when playing Baroque, whereas when playing Contemporary, the main seeds appear in the Cerebellar-Vermis, Insular cortex and Parietal Operculum. The discrepancies found are attributed to different cognitive, sensory and motor demands underlying the musical interpretation of each style, as well as to the musicians' learning of and training in these styles.

Temporo-parietal contribution to the mental representations of self/other face

Face recognition requires comparing the current visual input with stored mental representations of faces. Based on its role in visual recognition of faces and mental representation of the body, we hypothesized that the right temporo-parietal junction (rTPJ) could be implicated also in processing mental representation of faces. To test this hypothesis, we asked 30 neurotypical participants to perform mental rotation (laterality judgment of rotated pictures) of self- and other-face images, before and after the inhibition of rTPJ through repetitive transcranial magnetic stimulation. After inhibition of rTPJ the mental rotation of self-face was slower than other-face. In the control condition the mental rotation of self/other faces was not significantly different. This supports that the role of rTPJ extends to mental representation of faces, specifically for the self. Since the experimental task did not require to explicitly recognize identity, we propose that unconscious identity attribution affects also the mental representation of faces. The present study offers insights on the involvement rTPJ in mental representation of faces and proposes that the neural substrate dedicated to mental representation of faces goes beyond the traditional visual and memory areas.

The Role of Motor System in Mental Rotation: New Insights from Myotonic Dystrophy Type 1

OBJECTIVE

This study explored mental rotation (MR) performance in patients with myotonic dystrophy 1 (DM1), an inherited neuromuscular disorder dominated by muscular symptoms, including muscle weakness and myotonia. The aim of the study was twofold: to gain new insights into the neurocognitive mechanisms of MR and to better clarify the cognitive profile of DM1 patients. To address these aims, we used MR tasks involving kinds of stimuli that varied for the extent to which they emphasized motor simulation and activation of body representations (body parts) versus visuospatial imagery (abstract objects). We hypothesized that, if peripheral sensorimotor feedback system plays a pivotal role in modulating MR performance, then DM1 patients would exhibit more difficulties in mentally rotating hand stimuli than abstract objects.

METHOD

Twenty-four DM1 patients and twenty-four age- and education-matched control subjects were enrolled in the study and were required to perform two computerized MR tasks involving pictures of hands and abstract objects.

RESULTS

The analysis of accuracy showed that patients had impaired MR performance when the angular disparities between the stimuli were higher. Notably, as compared to controls, patients showed slower responses when the stimuli were hands, whereas no significant differences when stimuli were objects.

CONCLUSION

The findings are coherent with the embodied cognition view, indicating a tight relation between body- and motor-related processes and MR. They suggest that peripheral, muscular, abnormalities in DM1 lead to alterations in manipulation of motor representations, which in turn affect MR, especially when body parts are to mentally rotate.

High-Frequency rTMS of the Motor Cortex Modulates Cerebellar and Widespread Activity as Revealed by SVM

Functional magnetic resonance imaging (fMRI) studies have shown that the effect of repetitive transcranial magnetic stimulation (rTMS) can induce changes in remote brain regions. In the stimulated regions, low-frequency (≤1 Hz) rTMS induces inhibitory effects, while high-frequency (≥5 Hz) stimulation induces excitatory effects. However, these stereotypical effects arising from low- and high-frequency stimulation are based on measurements of motor evoked potentials (MEPs) induced by pulsed stimulation. To test the effects of rTMS on remote brain regions, the current study recruited 31 young healthy adults who participated in three rTMS sessions (10 Hz high frequency, 1 Hz low frequency, and sham) on three separate days. The stimulation target was based on individual fMRI activation in the motor cortex evoked by a finger movement task. Pre- and post-rTMS resting-state fMRI (RS-fMRI) were acquired. Regional homogeneity (ReHo) and degree centrality (DC) were calculated to measure the local and global connectivity, respectively. Compared with the sham session, high-frequency (10 Hz) rTMS significantly increased ReHo and DC in the right cerebellum, while low-frequency (1 Hz) stimulation did not significantly alter ReHo or DC. Then, using a newly developed PAIR support vector machine (SVM) method, we achieved accuracy of 93.18–97.24% by split-half validation for pairwise comparisons between conditions for ReHo or DC. While the univariate analyses suggest that high-frequency rTMS of the left motor cortex could affect distant brain activity in the right cerebellum, the multivariate SVM results suggest that both high- and low-frequency rTMS significantly modulated widespread brain activity. The current findings are useful for increasing the understanding of the mechanisms of rTMS, as well as guiding precise individualized rTMS treatment of movement disorders.

Mental rotation of sequentially presented 3D figures: sex and sex hormones related differences in behavioural and ERP measures

Mental rotation of 3D objects demonstrates one of the largest sex differences. We investigated sex and sex hormones-related differences in behaviour and event related potentials (ERP) using a modified Shepard and Metzler task composed of sequentially presented 3D figures in 29 men and 32 women. We demonstrated a significant increase in response time and decrease in both accuracy and positivity of the parietal ERP with increasing angular disparity between the figures. Higher angular disparity evoked an increase of global field power (GFP) from 270 to 460 ms and different activation topographies from 470 to 583 ms with lower parietal, but higher left frontal positivity. Flatter slopes in higher angular disparity condition suggest distinct strategies being implemented depending on the difficulty of the rotation. Men performed the task more accurately than women. Performance accuracy in women tended to be negatively related to estradiol while the response time tended to increase with increasing progesterone. There were no associations with testosterone. Women demonstrated higher GFP and an increased positivity over the parietal scalp area, while men showed higher activation in the left frontal cortex. Together these findings indicate dynamic angular disparity- and sex-related differences in brain activity during mental rotation of 3D figures.

Where is the "where" in the brain? A meta-analysis of neuroimaging studies on spatial cognition

Spatial representations are processed in the service of several different cognitive functions. The present study capitalizes on the Activation Likelihood Estimation (ALE) method of meta-analysis to identify: (a) the shared neural activations among spatial functions to reveal the "core" network of spatial processing; (b) the specific neural activations associated with each of these functions. Following PRISMA guidelines, a total of 133 fMRI and PET studies were included in the meta-analysis. The overall analysis showed that the core network of spatial processing comprises regions that are symmetrically distributed on both hemispheres and that include dorsal frontoparietal regions, presupplementary motor area, anterior insula, and frontal operculum. The specific analyses revealed the brain regions that are selectively recruited for each spatial function, such as the right temporoparietal junction for shift of spatial attention, the right parahippocampal gyrus, and the retrosplenial cortex for navigation and spatial long-term memory. The findings are integrated within a systematic review of the neuroimaging literature and a new neurocognitive model of spatial cognition is proposed.