Attention Modulates Earliest Responses in the Primary Auditory and Visual Cortices

Abstract

A fundamental question about the neural correlates of attention concerns the earliest sensory processing stage that it can affect. We addressed this issue by recording magnetoencephalography (MEG) signals while subjects performed detection tasks, which required employment of spatial or nonspatial attention, in auditory or visual modality. Using distributed source analysis of MEG signals, we found that, contrary to previous studies that used equivalent current dipole (ECD) analysis, spatial attention enhanced the initial feedforward response in the primary visual cortex (V1) at 55-90 ms. We also found attentional modulation of the putative primary auditory cortex (A1) activity at 30-50 ms. Furthermore, we reproduced our findings using ECD modeling guided by the results of distributed source analysis and suggest a reason why earlier studies using ECD analysis failed to identify the modulation of earliest V1 activity.

Learning related activation of somatosensory cortex by an auditory stimulus recorded with magnetoencephalography

“…Thus, in contrast to the current paradigm, in previous work participants were focusing only on stimulus presentation. Evoked responses in multiple sensory modalities have been shown to be substantially larger under conditions of direct attention ([Di Russo et al, 2003], [Giabbiconi et al, 2007], [Kida et al, 2004], [Martínez et al, 2006] and [Poghosyan and Ioannides, 2008]), and as mentioned previously, the evoked neural CR is smaller than the response to the US, even under conditions of direct attention (Moses et al, 2005). These observations may account for the lack of an evoked CR found in the current study.…”

Voluntary attention reliably influences visual processing at the level of the C1 component: A commentary on Fu, Fedota, Greenwood, and Parasuram (2010)

“…While it has long been assumed that the earliest stages of processing in V1 are resistant to top-down influences exerted by attentional control mechanisms (Hillyard et al, 1998;Martinez et al, 1999), our results concur with other recent findings (Fu et al, 2010a;Fu et al, 2009;Karns and Knight, 2009;Kelly et al, 2008;Khoe et al, 2005;Poghosyan and Ioannides, 2008) to suggest otherwise.…”

Alterations in Event Related Potentials (ERP) Associated with Tinnitus Distress and Attention

“…Depending on the emotional load of the tinnitus signal which defines its salience attention can be shifted more (low tinnitus related distress) or less (high tinnitus related distress) to the task. As the N1 wave of the ERP (Hillyard et al 1973;Coch et al 2005;Poghosyan and Ioannides 2008;Thornton et al 2007) is influenced by attention this results in higher differences in N1 amplitude between the attended and unattended stimulus conditions in patients with low tinnitus related distress as compared to patients with high distress.…”