Biology subjects

Esmeyer, M. F.

Publications and source records attributed to Esmeyer, M. F..

2 recordsLinked to original sources

bioRxiv2024

Decoding Parametric Grip-Force Anticipation from fMRI-Data

Previous functional magnetic resonance imaging (fMRI) studies have shown that activity in premotor and parietal brain-regions covaries with the intensity of upcoming grip-force. However, it remains unclear how information about the intended grip-force intensity is initially represented and subsequently transformed into a motor code before motor-execution. In this fMRI study, we used multivoxel pattern analysis (MVPA) to decode where and when information about grip-force intensities is parametrically coded in the brain. Human participants performed a delayed grip-force task in which one of four cued levels of grip-force intensity had to be maintained in working memory (WM) during a 9-second delay-period preceding motor execution. Using time-resolved MVPA, with a searchlight approach and support vector regression (SVR), we tested which brain regions exhibit multivariate WM codes of anticipated grip-force intensities. During an early delay-period, we observed above-chance decoding in the ventromedial prefrontal cortex (vmPFC). During a late delay-period, we found a network of action-specific brain regions, including the bilateral intraparietal sulcus (IPS), left dorsal premotor cortex (l-PMd) and supplementary motor areas (SMA). Additionally, cross-regression decoding was employed to test for temporal generalization of activation patterns between early and late delay-periods with those during cue presentation and motor execution. Cross-regression decoding indicated temporal generalization to the cue-period in the vmPFC, and to motor-execution in the l-IPS and l-PMd. Together, these findings suggest that the WM representation of grip-force intensities undergoes a transformation where the vmPFC encodes information about the intended grip-force, which is subsequently converted into a motor code in the l-IPS and l-PMd before execution.

neuroscience↗

bioRxiv2024

Effector-Specific Neural Representations of Perceptual Decisions Independent of Motor Actions and Sensory Modalities

Neuroscientific research has shown that perceptual decision-making occurs in effector-specific brain regions that are associated with the required motor response. Recent functional magnetic resonance imaging (fMRI) studies that dissociated decisions from coinciding processes, such as motor actions partly challenge this, indicating abstract representations that might vary across stimulus modalities. However, cross-modal comparisons have been difficult since most task designs differ not only in modality but also in effectors, motor response, and level of abstraction. Here, we describe an fMRI experiment where participants compared frequencies of two sequentially presented visual flicker stimuli in a delayed match-to-comparison task, which controlled for motor actions and stimulus sequence. Using Bayesian modelling, we estimated subjective frequency differences based on the time order effect. These values were applied in support vector regression analysis of a multi-voxel pattern whole-brain searchlight approach to identify brain regions containing information on subjective decision values. Furthermore, a conjunction analysis with data from a re-analyzed analogue vibrotactile study was conducted for a cross-modal comparison. Both analyses revealed significant activation patterns in the left dorsal (PMd) and ventral (PMv) premotor cortex as well as in the bilateral intraparietal sulcus (IPS). While previous primate and human imaging research have implicated these regions in transforming sensory information into action, our findings indicate that the IPS processes abstract decision signals while PMd and PMv represent an effector-specific, but motor response independent encoding of perceptual decisions that persists across sensory domains.

neuroscience↗