Biology subjects

Cloherty, S. L.

Publications and source records attributed to Cloherty, S. L..

4 recordsLinked to original sources

bioRxiv2026

Sensory origin of oculomotor variability revealed by MT population activity

Motor outputs vary even in response to identical sensory inputs, yet the origin of this variability within the sensorimotor pathway remains unresolved. Here, we evaluate how variability in sensory representations can explain behavioural fluctuations in a reflexive oculomotor task. We used Neuropixels probes to record neuronal activity in area MT of marmosets during ocular following responses and applied partial least squares regression to extract the shared variance between population activity and eye movements. Stimulus-evoked activity reliably predicted trial-by-trial variability in open-loop eye velocity. Additionally, closed-loop analyses revealed trial-by-trial correspondence between eye movements and subsequent neural responses. These results demonstrate that variability in sensory neural populations contributes to motor variability, supporting the claim that sensory noise is propagated through the sensorimotor pathway. Surprisingly, however, traditional models trained to only capture neural variability across trials poorly predicted behavioural variations, suggesting that only a subset of sensory representations is accessible to the motor system.

neuroscience↗

bioRxiv2023

Ocular following responses of the marmoset monkey are dependent on post-saccadic delay, spatiotemporal frequency and saccade direction

Ocular following is a short-latency, reflexive eye movement that tracks wide-field visual motion. It has been studied extensively in humans and macaques and is an appealing behaviour for studying sensory-motor transformations in the brain due to its rapidity and rigidity. We explored ocular following in the marmoset, an emerging model in neuroscience because their lissencephalic brain allows direct access to most cortical areas for imaging and electrophysiological recordings. In three experiments, we tested ocular following responses in three adult marmosets. First, we varied the gap between saccade end and stimulus motion onset (post-saccadic delay), from 10 to 300 ms. As in other species, tracking had shorter onset latencies and higher eye speeds with shorter post-saccadic delays. Second, using sine-wave grating stimuli we explored the dependence of eye speed on spatiotemporal frequency. The highest eye speed was evoked at [~]16 Hz and [~]0.16 cycles per degree (cpd), however, the highest gain was elicited at [~]1.6 Hz and [~]1.2 cpd. The highest eye speed for each spatial frequency was observed at a different temporal frequency, but this interdependence was not consistent with complete speed tuning of the ocular following response. Finally, we found the highest eye speeds when saccade and stimulus motion directions were congruent, although latencies were unaffected by direction congruence. Our results showed comparable ocular following in marmosets, humans and macaques, despite over an order of magnitude variation in body and eye size across species. This characterization will help future studies examining the neural basis of sensory-motor transformations. New & NoteworthyPrevious ocular following studies focused on humans and macaques. We examined the properties of ocular following responses in marmosets in three experiments, in which post-saccadic delay, spatial-temporal frequency of stimuli and congruency of saccade and motion directions were manipulated. We have demonstrated short-latency ocular following in marmosets, and discuss the similarities across three species that vary markedly in eye and head size. Our findings will help future studies examining the neural mechanism of sensory-motor transformations.

neuroscience↗

bioRxiv2022

Neural responses to broadband visual flicker in marmoset primary visual cortex

Temporal information is ubiquitous in natural vision and must be represented accurately in the brain to allow us to interact with a constantly changing world. Recent studies have employed a random stimulation paradigm to map the temporal response function (TRF) to luminance changes in the human EEG. This approach has revealed that the visual system, when presented with broadband visual input, actively selects distinct temporal frequencies, and retains their phase-information for prolonged periods of time. This non-linear response likely originates in primary visual cortex (V1), yet, so far it has not been investigated on a neural level. Here, we characterize the steady-state response to random broadband visual flicker in marmoset V1. In two experiments, we recorded from i) marmosets passively stimulated under general anesthesia, and ii) awake marmosets, under free viewing conditions. Our results show that LFP coupling to the stimulus was broadband and unselective under anesthesia, whereas in awake animals, it was restricted to two distinct frequency components, in the alpha and beta range. Within these frequency bands, coupling adhered to the receptive field (RF) boundaries of the local populations. The responses outside the RF did not provide evidence for a propagation of stimulus information across the cortex, contrary to results in human EEG studies. This result may be explained by short fixation durations, warranting further investigation. In summary, our findings show that during awake behavior V1 neural responses to broadband information are selective for distinct frequency bands, and that this selectivity is likely controlled actively by top-down mechanisms.

neuroscience↗

bioRxiv2019

Motion perception in the common marmoset

Visual motion processing is a well-established model system for studying neural population codes in primates. The common marmoset, a small new world primate, offers unparalleled opportunities to probe these population codes in key motion processing areas, such as cortical areas MT and MST, because these areas are accessible for imaging and recording at the cortical surface. However, little is currently known about the perceptual abilities of the marmoset. Here, we introduce a paradigm for studying motion perception in the marmoset and compare their psychophysical performance to human observers. We trained two marmosets to perform a motion estimation task in which they provided an analog report of their perceived direction of motion with an eye movement to a ring that surrounded the motion stimulus. Marmosets and humans exhibited similar trade-offs in speed vs. accuracy: errors were larger and reaction times were longer as the strength of the motion signal was reduced. Reverse correlation on the temporal fluctuations in motion direction revealed that both species exhibited short integration windows, however, marmosets had substantially less non-decision time than humans. Our results provide the first quantification of motion perception in the marmoset and demonstrate several advantages to using analog estimation tasks.

neuroscience↗