Biology subjects

Klaes, C.

Publications and source records attributed to Klaes, C..

3 recordsLinked to original sources

bioRxiv2025

Spontaneous eye movements reveal that premotor cortex is involved in human thinking

Non-visual saccades (NVS) are spontaneous eye movements humans make while thinking. Their role is puzzling and there is no framework to explain them in terms of underlying neural systems. Here we studied neural activity preceding NVS when subjects performed standardized abstract thinking tasks. We used high-density EEG and focused on frontal and parietal channels representing oculomotor cortical areas. We found that NVS are distinctively preceded by neural activity changes in frontal and parietal EEG channels qualitatively different to that for voluntary saccades. However, only the ERP amplitude changes in frontal channels, but not in parietal channels, were different from saccadic preparation. A source reconstruction analysis additionally revealed that presaccadic neural activity originated mainly in the premotor cortex. Frequency spectrum analyses showed increased synchronization in alpha to low gamma bands suggesting complex top-down and bottom-up processing. We propose that this presaccadic activity while thinking represents evidence accumulation and attentional shifts, as shown before in the premotor cortex during sensorimotor tasks. Our findings suggest that human thinking appears to function similarly to human actions and engages premotor areas responsible for evaluating and manipulating objects also when evaluating and manipulating concepts.

neuroscience↗

bioRxiv2023

Neural representations of economic decision variables in human posterior parietal cortex

Decision making has been intensively studied in the posterior parietal cortex in non-human primates on a single neuron level. In humans decision making has mainly been studied with psychophysical tools or with fMRI. Here, we investigated how single neurons from human posterior parietal cortex represent numeric values informing future decisions during a complex two-player game. The tetraplegic study participant was implanted with a Utah electrode array in the anterior intraparietal area (AIP). We played a simplified variant of Black Jack with the participant while neuronal data was recorded. During the game two players are presented with numbers which are added up. Each time a number is presented the player has to decide to proceed or to stop. Once the first player stops or the score reaches a limit the turn passes on to the second player who tries to beat the score of the first player. Whoever is closer to the limit (without overshooting) wins the game. We found that many AIP neurons selectively responded to the face value of the presented number. Other neurons tracked the cumulative score or were selectively active for the upcoming decision of the study participant. Interestingly, some cells also kept track of the opponents score. Our findings show that parietal regions engaged in hand action control also represent numbers and their complex transformations. This is also the first demonstration of complex economic decisions being possible to track in single neuron activity in human AIP. Our findings show how tight are the links between parietal neural circuits underlying hand control, numerical cognition and complex decision-making.

neuroscience↗

bioRxiv2023

Phantom touch illusion: Unexpected phenomenological effects of tactile gating in the absence of tactile stimulation

We report the presence of a tingling sensation perceived during self touch without physical stimulation. We used immersive virtual reality scenarios in which subjects touched their body using a virtual object. This touch resulted in a tingling sensation corresponding to the location touched on the virtual body. We called it "phantom touch illusion" (PTI). Interestingly the illusion was also present when subjects touched invisible (inferred) parts of their limb. We reason that this PTI results from tactile gating process during self-touch. The reported PTI when touching invisible body parts indicates that tactile gating is not exclusively based on vision, but rather on multi-sensory, top-down input involving body schema. This finding shows that representations of own body are defined top-down, beyond the available sensory information.

neuroscience↗