Visual Attention FEF V4 spatial attention: simultaneous - - PDF document

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Visual Attention

spatial attention:

Ÿ simultaneous neural recordings in V4 & Frontal Eye Fields (monkeys) Gregoriou, Gotts, Zhou, Desimone (2010) V4 ¡ FEF ¡

• bject attention:

Ÿ MEG & fMRI in FFA (faces), PPA (places), & Inferior Frontal Junction (humans) Baldauf & Desimone (2014)

Technical Preliminaries

Local Field Potential: 0.7 – 100 Hz Spikes: 100 – 8000 Hz

Temporal synchrony:

Spike triggered average of LFP (STA):

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Gregoriou et al.: spatial attention

Ÿ firing rate increases for attended stimulus Ÿ increase in V4 response follows the increase in FEF response, in time

Temporal synchrony

Coherence between spikes and LFPs at different temporal frequencies (Hz) Ÿ increase in spike-field coherence in gamma band for attention inside the RF... ... especially when comparing between FEF and V4 Ÿ consistent temporal delay ~10-12 ms from FEF à V4

Coherence ≈ phase locking between two signals as a function of frequency

¡

Hypothesis about control

• f spatial attention?

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Object Attention Magnetoencephalography (MEG)

• measures magnetic fields generated by

neuronal activity, non-invasively

• analyze spatial distributions of magnetic

fields to localize source of neuronal activity

• superimpose source locations on MRI images
• high temporal resolution (~10 ms)
• high spatial resolution (~ 1 mm)
• magnetic fields are extremely small, require

very sensitive instrumentation and methods to eliminate environmental interference

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FFA/PPA/IFJ: power & coherence

Ÿ increased power in IFJ & FFA at 2 Hz when attending faces Ÿ increased power in IFJ & PPA at 1.5 Hz when attending houses Ÿ associated increases in coherence between IFJ and FFA/PPA, also in gamma frequency band, temporal delay in coherence IFJ à FFA/PPA ~ 20 ms

Hypothesis about control of spatial attention?