Biology subjects

van Kerkoerle, T.

Publications and source records attributed to van Kerkoerle, T..

4 recordsLinked to original sources

bioRxiv2026

From Coarse to Rich: Successive Waves of Visual Perception in Prefrontal Cortex

The ventrolateral prefrontal cortex (vlPFC) is well known for its involvement in high-level functions such as cognitive control and language. However, vlPFCs role in visual processing is less clear. Here, we investigated how neuronal ensembles in the vlPFC dynamically encode different types of visual information. Using chronic recording of spiking activity, we investigated vlPFCs representational geometry in a macaque monkey passively viewing a large set of naturalistic images, and compared this to representations in deep neural networks (DNNs). We found that the vlPFC processes visual information in two stages. First, an "early" response from 50 to 90 ms after stimulus onset encodes the low spatial frequency component of an image. It contains sufficient information to form a coarse estimate of the position and category of a salient object. Then, from 100 ms on, the representational geometry changes and contains much richer information. This late period contains non-categorical information typically present in conscious experiences such as the orientation of a face and natural scenes in the background. The late window also enables sub-category identification, which is boosted by the low spatial category prior. These results suggest that the vlPFC has a dual role in natural vision: first forming fast low-spatial-frequency-based priors shaping feed-forward visual processing, and subsequently maintaining a detailed and rich representation of a visual scene. SignificanceWhat information does the prefrontal cortex represent during natural vision, and how does this relate to conscious experience? Theories of consciousness differ sharply on whether prefrontal activity reflects detailed perceptual content or only high-level, task-related information. Using dense neural recordings during passive viewing of thousands of naturalistic images, we show that the ventrolateral prefrontal cortex processes visual information in two distinct stages: an early, coarse estimate of the visual scene is followed by a richer, high-dimensional representation that includes sub-category identity and other perceptual details. These findings reveal that prefrontal circuits encode more of the content of visual experience than previously assumed, even in the absence of a task.

neuroscience↗

bioRxiv2024

Comparison of the cortical hierarchy between macaque monkeys and mice based on cell-type specific microcircuits

The primate neocortex contains a hierarchy of cortical areas, with feedforward connections running from lower to higher levels, and feedback connections running in the opposite direction. The relative hierarchical position of cortical areas has been well established by retrograde tracing studies that allow to determine whether type of output from different source areas is predominantly feedforward or feedback. This method can not determine whether the cortico-cortical input within target areas is predominantly feedforward or feedback. We here make use of cell-type specific microcircuits to provide an intrinsic measure of the strength of feedforward versus feedback processing within cortical areas in macaque monkeys and mice. This allows a more complete map of the cortical hierarchy of different species, and therefore a more direct cross-species comparison. Parvalbumin-expressing interneurons were used as a marker of feedforward processing and calretinin-expressing interneurons as a marker of feedback processing. We found steep gradients in the distributions of these two interneuron types across macaque monkey cortical areas, indicating a deep cortical hierarchy where early visual areas are dominated by feedforward neural circuits and higher cortical areas become dominated by top-recurrent circuits. In contrast, the gradient in interneuron distribution across mouse cortical areas was limited, indicating a shallow cortical hierarchy and remaining dominated by feedforward neural circuits. This implies that the mouse cortex is comparable to early visual areas in primates, remaining dominated by bottom-up input. While primates are unique in having a deep cortical hierarchy that allows neural processing in higher cortical areas to become predominantly internal. Significance statementThe cortex in primates is known to contain a hierarchy of cortical areas, where bottom-up processing allows sensory information to get more and more compressed towards higher cortical areas, and where top-down processing allows lower areas to remain informed about the internal goals of the animal. However, it has been challenging to directly compare cortical hierarchies between animal species. Here, we developed an intrinsic measure of the strength of bottom-up and top-down processing within cortical areas, based on the density of different types of interneurons within areas. Or results indicate that the mouse cortical hierarchy is shallow and is driven by bottom-up processing, while the primate cortical hierarchy is deep and slowly becomes dominated by internal processing towards the top.

neuroscience↗

bioRxiv2023

Brain mechanisms of reversible symbolic reference:a potential singularity of the human brain

The emergence of symbolic thinking has been proposed as a dominant cognitive criterion to distinguish humans from other primates during hominization. Although the proper definition of a symbol has been the subject of much debate, one of its simplest features is bidirectional attachment: the content is accessible from the symbol, and vice versa. Behavioural observations scattered over the past four decades suggest that this criterion might not be met in non-human primates, as they fail to generalise an association learned in one temporal order (A to B) to the reverse order (B to A). Here, we designed an implicit fMRI test to investigate the neural mechanisms of arbitrary audio-visual and visual-visual pairing in monkeys and humans and probe their spontaneous reversibility. After learning a unidirectional association, humans showed surprise signals when this learned association was violated. Crucially, this effect occurred spontaneously in both learned and reversed directions, within an extended network of high-level brain areas, including, but also going beyond, the language network. In monkeys, by contrast, violations of association effects occurred solely in the learned direction and were largely confined to sensory areas. We propose that a human-specific brain network may have evolved the capacity for reversible symbolic reference.

neuroscience↗

bioRxiv2021

Prefrontal neural ensembles encode an internal model of visual sequences and their violations

When exposed to sensory sequences, do macaque monkeys spontaneously form abstract internal models that generalize to novel experiences? Here, we show that neuronal populations in macaque ventrolateral prefrontal cortex encode visual sequences by factorizing them into separate codes for the specific pictures presented and for their abstract sequential structure. Ventrolateral prefrontal neurons were recorded while macaque monkeys passively viewed visual sequences and sequence mismatches in the local-global paradigm. Even without any overt task or response requirements, prefrontal populations spontaneously built up representations of sequence structure, serial order, and image identity within distinct but superimposed neuronal subspaces. Representations of sequence structure rapidly updated following single exposure to a mismatch sequence, while orthogonal populations represent mismatches for sequences of different complexity. Finally, those representations generalized across sequences following the same structure but comprising different images. These results suggest that prefrontal populations spontaneously encode rich internal models of visual sequences that reflect both content-specific and abstract information.

neuroscience↗