Visual Attention FEF V4 spatial attention: simultaneous - PDF document

10/29/14 ¡ Visual Attention FEF ¡ V4 ¡ spatial attention: Ÿ simultaneous neural recordings in V4 & Frontal Eye Fields (monkeys) Gregoriou, Gotts, Zhou, Desimone (2010) object attention: Ÿ MEG & fMRI in FFA (faces), PPA (places), & Inferior Frontal Junction (humans) Baldauf & Desimone (2014) Technical Preliminaries Temporal synchrony: Local Field Potential: 0.7 – 100 Hz Spikes: 100 – 8000 Hz Spike triggered average of LFP (STA): 1 ¡

10/29/14 ¡ 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 ≈ phase locking between two signals as a function of frequency ¡ 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 Hypothesis about control of spatial attention? Coherence between spikes and LFPs at different temporal frequencies (Hz) 2 ¡

10/29/14 ¡ 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 3 ¡

10/29/14 ¡ 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 Hypothesis about Ÿ associated increases in coherence between IFJ and FFA/PPA, control of spatial also in gamma frequency band, temporal delay in coherence attention? IFJ à FFA/PPA ~ 20 ms 4 ¡