Biology subjects

Lorteije, J. A. M.

Publications and source records attributed to Lorteije, J. A. M..

3 recordsLinked to original sources

bioRxiv2026

Sound-evoked orofacial motion only affects a fraction of visually responsive V1 neurons in a multisensory detection task with delayed reward delivery

Auditory stimuli have been known to elicit neural responses in visual cortical areas, but such responses are partly associated with sound-evoked orofacial movements. However, it remains unclear to what extent neural correlates of movement can be dissociated from non-motor correlates. Here we developed a paradigm with a forced delayed-response mechanism by means of a moving reward apparatus in order to test whether this results in low amounts of movement-related neural activity shortly after stimulus onset. Animals performed a multisensory detection task, while we recorded neural activity from V1 and measured orofacial motion. During the delay, when only the stimulus was present, orofacial motion was relatively low. Reward-related motion increased after the delay, with a concomitant increase in motor-related spiking activity. Visual stimulation did neither elicit considerable motion nor corresponding neural responses in the delay period. Conversely, salient auditory stimuli led to modest, but increased orofacial motion and related neuronal activity during the delay. We identified a subpopulation of visually responsive V1 neurons that did not show correlations with orofacial movement, with only the stimulus being represented. These results present a forced delayed-response window as a method to help disentangle motor-related activity from visual (but not auditory) processing and show that motor-related activity only affects a fraction of visually selective neurons.

neuroscience↗

bioRxiv2022

Pop-in: the inversion of pop-out for a feature dimension during visual search in area V4 of the monkey cortex

During visual search, it is important to reduce the interference of distracting objects in the scene. The neuronal responses elicited by the search target stimulus are typically enhanced. However, it is equally important to suppress the representations of distracting stimuli, especially if they are salient and capture attention. We trained monkeys to make an eye movement to a unique pop-out shape stimulus among an array of distracting stimuli. One of these distractors had a salient color that varied across trials and differed from the color of the other stimuli, causing it to also pop-out. The monkeys were able to select the pop-out shape target with high accuracy and actively avoided the pop-out color distractor. This behavioral pattern was reflected in the activity of neurons in area V4. Responses to the shape targets were enhanced, while the activity evoked by the pop-out color distractor was only briefly enhanced, directly followed by a sustained period of pronounced suppression. These behavioral and neuronal results demonstrate a cortical selection mechanism that rapidly inverts a pop-out signal to pop-in for an entire feature dimension thereby facilitating goal-directed visual search in the presence of salient distractors. Significance statementGoal-directed behaviors like visual search involve both the selection of behaviorally relevant targets and the suppression of task-irrelevant distractors. This is especially important if distractors are salient and capture attention. Here we demonstrate that non-human primates suppress a salient color distractor while searching for a target that is defined by shape, i.e. another feature dimension. The neuronal activity of V4 neurons revealed the temporal evolution of target selection and distractor suppression. The neuronal responses elicited by the pop-out target stimuli were enhanced whereas responses elicited by salient pop-out color distractors were suppressed, after an initial brief phase of response enhancement. Our results reveal a pop-in mechanism by which the visual cortex inverts an attentional capture signal into suppression to facilitate visual search.

neuroscience↗

bioRxiv2018

Feedforward and feedback processing during figure-ground perception in mice

The segregation of figures from the background is an important step in visual perception. In primary visual cortex, figures evoke stronger activity than backgrounds during a delayed phase of the neuronal responses, but it is unknown how this figure-ground modulation (FGM) arises and whether it is necessary for perception. Here we show, using optogenetic silencing in mice, that the delayed V1 response phase is necessary for figure-ground segregation. Neurons in higher visual areas also exhibit FGM and optogenetic silencing of higher areas reduced FGM in V1. In V1, figures elicited higher activity of vasoactive intestinal peptide-expressing (VIP) interneurons than the background, whereas figures suppressed somatostatin-positive interneurons, resulting in an increased activation of pyramidal cells. Optogenetic silencing of VIP neurons reduced FGM in V1, indicating that disinhibitory circuits contribute to FGM. Our results provide new insight in how lower and higher areas of the visual cortex interact to shape visual perception.

neuroscience↗