# Role of fixational eye movements and saccades in processing spatial information in V1-V2-V4 networks

> **NIH NIH R01** · WEILL MEDICAL COLL OF CORNELL UNIV · 2024 · $519,960

## Abstract

This project focuses on cortical mechanisms in areas V1, V2, and V4 (V1-2-4) underlying the information-
processing roles of saccades and fixational eye movements (FxEMs: microsaccades and drift) in vision. Both
saccades and microsaccades are followed by drift. Sequences of saccade/drift and microsaccade/drift cycles,
both of which we will refer to as saccade/drift cycles (SDC’s), are believed to be critical to gathering information
about visual scenes and the objects within them. We will record single-unit and local field potential (LFP) activity
from the foveal projection in areas V1-2-4 simultaneously while monkeys perform match-to-sample tasks for
shape or texture, with shapes filled with texture, to understand the role of SDC’s in cortical processing during
active vision. Through the use of gaze-stabilization, we will be able to disrupt the retinal input to the cortex during
the task to probe selectively how SDC’s control processing of shape and texture in early visual areas.
 In active vision, the SDC maps spatial information into temporal patterns of neural activity. Recent modeling
and psychophysical work have determined that the initial transient phase of the cycle encodes coarse features,
while the later, more prolonged period of drift is critical for extracting fine details. We are interested in how the
transition from coarse to fine processing in the SDC is implemented in local and inter-areal cortical networks.
We hypothesize that processing in these networks during the SDC begins with a phase of transient feedforward
activity followed by a longer phase of recurrent and re-entrant activity that coincides with gamma oscillations in
the networks. We hypothesize that shape is captured in the initial phase of the SDC and finer features of the
shape’s border and the region within the shape by the recurrent phase of processing during drift. We also suggest
that the cortex uses sequences of SDC’s to accumulate information and that the organization of networks within
the cortex, in terms of their hierarchy and temporal frequency band for communication, depends on whether the
sequence is dominated by saccades and drift (looking) or by microsaccades and drift (fixating).
 In AIM 1, we focus on activity phase-locked to the SDC where the match to sample for shape or texture is
fixed for an entire day’s session. The SDC’s in this task will be dominated by microsaccades/drifts. We will ask
if accurate matches for shape coincide with stronger SDC transients in the network and if accurate matches for
texture produce robust gamma coherence that emerges later in the SDC. In AIM 2, we investigate sequences of
SDC’s in periods of looking and fixating for a match-to-sample task where the monkey is given a cue on every
trial for the correct match of shape or texture. Information is gained across the trial through saccades and FxEMs,
and we ask how the dynamics of V1-2-4 network activity, phase-locked to these sequences, reflect performance
and task. Gaze-...

## Key facts

- **NIH application ID:** 10850871
- **Project number:** 5R01EY034150-03
- **Recipient organization:** WEILL MEDICAL COLL OF CORNELL UNIV
- **Principal Investigator:** Keith P. Purpura
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $519,960
- **Award type:** 5
- **Project period:** 2022-09-01 → 2026-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10850871

## Citation

> US National Institutes of Health, RePORTER application 10850871, Role of fixational eye movements and saccades in processing spatial information in V1-V2-V4 networks (5R01EY034150-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10850871. Licensed CC0.

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