Presentation is loading. Please wait.

Presentation is loading. Please wait.

Synchronous activity within and between areas V4 and FEF in attention Steve Gotts Laboratory of Brain and Cognition NIMH, NIH with: Georgia Gregoriou,

Similar presentations


Presentation on theme: "Synchronous activity within and between areas V4 and FEF in attention Steve Gotts Laboratory of Brain and Cognition NIMH, NIH with: Georgia Gregoriou,"— Presentation transcript:

1 Synchronous activity within and between areas V4 and FEF in attention Steve Gotts Laboratory of Brain and Cognition NIMH, NIH with: Georgia Gregoriou, Hui Hui Zhou, and Bob Desimone

2 Visual Selective Attention: The ability to monitor an object or location selectively in a crowded visual scene Cue Biased Competition Theory (Desimone & Duncan, 1995):  Multiple visual stimuli activate competing populations of neurons in visual cortex ("bottom up")  Attention biases this competition in favor of the attended stimulus ("top down") V1 PG TE PFC

3 V4 TE V1 PFC Attention and Extrastriate Cortex: Attentional modulation of neural responses is observed in extrastriate cortical regions such as V4 (e.g. Moran & Desimone, 1985; Fries, Reynolds, Rorie, & Desimone, 2001) Extrastriate lesions produce attentional deficits when salient distractors are present (e.g. De Weerd, Peralta, Desimone, & Ungerleider, 1999)

4 Good Stimulus Pair Time (ms) RF Fixation Good Stimulus Poor StimulusPair Spikes per second 1002003000 80 0 20 40 60 Spikes per second Poor Stimulus Reynolds et al., 1999

5 Good Stimulus Pair Time (ms) RF Fixation Good Stimulus Poor StimulusAttend Good Spikes per second 1002003000 80 0 20 40 60 Spikes per second Poor Stimulus Reynolds et al., 1999 Attend Good

6 Good Stimulus Pair Time (ms) RF Fixation Good Stimulus Poor StimulusAttend Poor Spikes per second 1002003000 80 0 20 40 60 Spikes per second Poor Stimulus Reynolds et al., 1999 Attend Poor

7 Fries, Reynolds, Rorie, and Desimone (Science, 2001) Attentional Modulation of Neural Synchrony in Area V4

8 What is the source of the "top down" attentional bias in extrastriate neurons ? One possibility (among several) is prefrontal cortex (PFC), which is thought to play a central role in cognitive control, executive function, and working memory: Feedback to temporal and parietal regions, which in turn feedback to extrastriate Imaging studies of selective attention in humans commonly show PFC activation Lesions of PFC in humans result in a variety of attentional deficits Rossi et al.: lesions to PFC in monkeys produces an impairment in switching top-down control

9 Stimulation of FEF influences activity in V4: Moore & Armstrong (2003) Moore & Fallah (2004) Interaction between areas FEF and V4 in attention  Record from V4 and FEF simultaneously during visual selection  Measure time course of changes in firing rate and synchrony both within and between regions V4 TE V1 FEF FEF implicated in visual attention in monkeys and humans: Corbetta & Shulman (2002) Moore & Fallah (2001) Schall (2004)

10 Task: Monitor stimulus that matches cue for a color change, ignoring changes in distractors Stimuli: Oriented, drifting, sinusoidal gratings (R,G,B) at 5 0 eccentricity Cue:  Random cue onset, ranging from 1 sec before stimulus onset to 1 sec after  Cue color chosen randomly for each trial Targets: change between 250 ms and 3 sec post-cue (or post-stim) Distractors: 0, 1, or 2 might change

11 Fixation: 0 – 500 ms Cue before stimuli: Cue on: 500 – 1500 msStimuli on: 1500 ms Target change: 250-3000 ms post-stimuli Fixation: 0 – 1500 ms Stimuli before cue: Stimuli on: 1500 ms Target change: 250-3000 ms post-cue Cue on: 1500 – 2500 ms

12 Effect of attention on firing rates FEF (N=30 MUs) V4 (N=31 MUs) Cue before stimCue after stim

13 Distribution of FR separation times (targets vs distractors) Cue before stim Cue after stim

14 Effect of attention on spike-LFP coherence Spikes in V4, LFP in V4 (different electrodes)

15 Effect of attention on spike-LFP coherence (cont.) Spikes in FEF, LFP in FEF (different electrodes)

16 Effect of attention on coherence across regions Spikes in FEF, LFP in V4

17 Spikes in V4, LFP in FEF Effect of attention on coherence across regions (cont.)

18 Effect of attention on V4-FEF phase relationships Within-regionBetween-region  Spike-triggered average (STA) of LFP  STAs band-pass filtered 35-80 Hz Results:  ~ Synchrony within regions  Phase-shift of 10 ms between regions

19 Distribution of gamma phase across electrode pairs Within-regionBetween-region

20 Time course of coherence: spikes in FEF, LFP in FEF

21 Time course of coherence: spikes in V4, LFP in V4

22 Time course of coherence: spikes in FEF, LFP in V4

23 Time course of coherence: spikes in V4, LFP in FEF


Download ppt "Synchronous activity within and between areas V4 and FEF in attention Steve Gotts Laboratory of Brain and Cognition NIMH, NIH with: Georgia Gregoriou,"

Similar presentations


Ads by Google