RTMS over bilateral inferior parietal cortex induces decrement of spatial sustained attention

Jeyeon Lee,Kyung Ran Kim,Hyeongrae Lee,Dong Pyo Jang,Eun Lee,In Young Kim,Masud Husain,Jinsick Park,Jeonghun Ku,Sun I Kim,Kang Jun Yoon,Kiwan Han

doi:10.3389/fnhum.2013.00026

Abstract

Sustained attention is an essential brain function that enables a subject to maintain attention level over the time of a task. In previous work, the right inferior parietal lobe (IPL) has been reported as one of the main brain regions related to sustained attention, however, the right lateralization of vigilance/sustained attention is unclear because information about the network for sustained attention is traditionally provided by neglect patients who typically have right brain damage. Here, we investigated sustained attention by applying a virtual lesion technique, transcranial magnetic stimulation (TMS), over the left and right superior parietal lobe (SPL) and IPL. We used two different types of visual sustained attention tasks: spatial (location based) and non-spatial (feature based). When the participants performed the spatial task, repetitive TMS (rTMS) over either the right or left IPL induced a significant decrement of sustained attention causing a progressive increment of errors and response time. In contrast, participants' performance was not changed by rTMS on the non-spatial task. Also, omission errors (true negative) gradually increased with time on right and left IPL rTMS conditions, while commission errors (false positive) were relatively stable. These findings suggest that the maintenance of attention, especially in tasks regarding spatial location, is not uniquely lateralized to the right IPL, but may also involve participation of the left IPL.

Highlights

Sustained attention or vigilance can be defined as the ability to maintain or control attention over prolonged periods of time, allowing the subject to respond to critical stimuli or to inhibit responses to irrelevant stimuli (Davies and Parasuraman, 1982; Warm, 1993)
Further supporting research is required to assure that the right inferior parietal lobe (IPL) is involved in spatial sustained attention because many patients who participate in lesion studies generally have damage extending across other regions besides the IPL
As a result from one-tailed t-test for the betas separately for every condition, significant difference of errors was found in right IPL (t = 3.929, df = 15, p = 0.001) and left IPL stimuli condition (t = 3.902, df = 15, p = 0.001) during spatial task, whereas no significant change of errors and response time was found irrespective of target area in non-spatial task (Table 1)

Summary

Introduction

Sustained attention or vigilance can be defined as the ability to maintain or control attention over prolonged periods of time, allowing the subject to respond to critical stimuli or to inhibit responses to irrelevant stimuli (Davies and Parasuraman, 1982; Warm, 1993). Brain imaging studies during tasks requiring sustained attention using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have demonstrated changes in cerebral blood flow and glucose metabolism in the ventral frontal cortex and inferior parietal lobe (IPL) suggesting their involvement (Coull et al, 1998; Adler et al, 2001; Demeter et al, 2010; Tana et al, 2010). Studies of patients with hemineglect provide evidence that right IPL and ventral frontal cortex are crucial regions for either sustained attention or vigilance (Hjaltason et al, 1996; Robertson et al, 1997; Samuelsson et al, 1998). There is no pre-existing data in the literature explaining involvement of the left parietal cortex as related to sustained attention

Methods

Results

Conclusion