Neural Mechanisms of Visual Attention: How Top-Down Feedback Highlights Relevant Locations

@article{citeulike:1391621, abstract = {Attention helps us process potentially important objects by selectively increasing the activity of sensory neurons that represent the relevant locations and features of our environment. This selection process requires top-down feedback about what is important in our environment. We investigated how parietal cortical output influences neural activity in early sensory areas. Neural recordings were made simultaneously from the posterior parietal cortex and an earlier area in the visual pathway, the medial temporal area, of macaques performing a visual matching task. When the monkey selectively attended to a location, the timing of activities in the two regions became synchronized, with the parietal cortex leading the medial temporal area. Parietal neurons may thus selectively increase activity in earlier sensory areas to enable focused spatial attention. 10.1126/science.1139140}, author = {Saalmann, Yuri B. and Pigarev, Ivan N. and Vidyasagar, Trichur R. }, citeulike-article-id = {1391621}, comment = {* electrophysiological study of neurons in monkey LIP and MT, examining the relative timing of activity to investigate top-down attentional feedback and mechanisms of visual attention * Simultaneous spiking and LFP recordings were made from 29 pairs of LIP and MT neurons with overlapping RFs and the same preferred orientation * The task was a DMS where monkeys had to match both the orientation and location of two sequentially presented gratings * In the ''spatial and feature-based attention'' condition, both S1 and S2 have the preferred orientation and occur in the RF, in the ''spatial attention'' condition, S1 and S2 occur in the RF but S1 has a nonpreferred and S2 a preferred orientation; in both cases the delay period after S2 is used * The ''attention elsewhere'' control is activity after S2 onset when S1 occurs outside and S2 inside the RF with the preferred orientation; the ''neutral'' control is post-S1 activity when S1 is the preferred orientation and in the RF * MT neurons are affected by attention: activity during S2 presentation was greater in the ''spatial and feature'' and ''spatial'' attention conditions compared to ''attention elsewhere'' * LIP neurons show greater activity in the ''spatial and feature'' attention compared to ''neutral'' but decreased activity for ''attention elsewhere''; ''spatial attention'' activity is also greater than ''attention elsewhere'' activity but similar to ''neutral'' activity during S1 preferred orientation presentation * LIP neurons also showed delay periods attention effects, with significantly greater activity when attention included the RF * LFP showed increased coherence between MT and LIP in the ''spatial and feature'' and ''spatial'' attention conditions, particularly in the 10-35 Hz range; there is significantly less coherence when the S1 stimulus occurs outside the RF * Similarly, there is a significant (but weaker) coherence between LIP and MT spiking activity, seen in 34\% of neuron pairs, with a phase shift suggesting that LIP leads MT in the ''spatial and feature'' and the ''spatial'' attention conditions * ''smaller effect expected given decreased likelihood of coupling when sampling pairs of neurons'' * Increased spike-field coherence within LIP in both spatial attention conditions compared to attention elsewhere suggests that synchronization within LIP may be important to increase downstream impact * Based on the apparent object feature selectivity (here for orientation), the authors suggest that LIP can, despite being in the dorsal stream, display feature selectivity (also see 'Gottlieb et al 1998':http://www.citeulike.org/user/klouie/article/90447 and 'Balan and Gottlieb 2006':http://www.citeulike.org/user/klouie/article/843521 ) and may mediate top-down attentional effects in object processing, either through direct connections to the ventral stream or gating V1 activity via MT}, doi = {10.1126/science.1139140}, journal = {Science}, keywords = {attention, electrophysiology, lip, monkey, mt, \_note}, month = {June}, number = {5831}, pages = {1612--1615}, posted-at = {2008-03-05 16:15:18}, priority = {2}, title = {Neural Mechanisms of Visual Attention: How Top-Down Feedback Highlights Relevant Locations}, url = {http://dx.doi.org/10.1126/science.1139140}, volume = {316}, year = {2007} }

TY - JOUR ID - citeulike:1391621 L3 - citeulike-article-id:1391621 TI - Neural Mechanisms of Visual Attention: How Top-Down Feedback Highlights Relevant Locations JF - Science VL - 316 IS - 5831 SP - 1612 EP - 1615 N2 - Attention helps us process potentially important objects by selectively increasing the activity of sensory neurons that represent the relevant locations and features of our environment. This selection process requires top-down feedback about what is important in our environment. We investigated how parietal cortical output influences neural activity in early sensory areas. Neural recordings were made simultaneously from the posterior parietal cortex and an earlier area in the visual pathway, the medial temporal area, of macaques performing a visual matching task. When the monkey selectively attended to a location, the timing of activities in the two regions became synchronized, with the parietal cortex leading the medial temporal area. Parietal neurons may thus selectively increase activity in earlier sensory areas to enable focused spatial attention. 10.1126/science.1139140 KW - attention KW - electrophysiology KW - lip KW - monkey KW - mt KW - _note N1 - * electrophysiological study of neurons in monkey LIP and MT, examining the relative timing of activity to investigate top-down attentional feedback and mechanisms of visual attention * Simultaneous spiking and LFP recordings were made from 29 pairs of LIP and MT neurons with overlapping RFs and the same preferred orientation * The task was a DMS where monkeys had to match both the orientation and location of two sequentially presented gratings * In the ''spatial and feature-based attention'' condition, both S1 and S2 have the preferred orientation and occur in the RF, in the ''spatial attention'' condition, S1 and S2 occur in the RF but S1 has a nonpreferred and S2 a preferred orientation; in both cases the delay period after S2 is used * The ''attention elsewhere'' control is activity after S2 onset when S1 occurs outside and S2 inside the RF with the preferred orientation; the ''neutral'' control is post-S1 activity when S1 is the preferred orientation and in the RF * MT neurons are affected by attention: activity during S2 presentation was greater in the ''spatial and feature'' and ''spatial'' attention conditions compared to ''attention elsewhere'' * LIP neurons show greater activity in the ''spatial and feature'' attention compared to ''neutral'' but decreased activity for ''attention elsewhere''; ''spatial attention'' activity is also greater than ''attention elsewhere'' activity but similar to ''neutral'' activity during S1 preferred orientation presentation * LIP neurons also showed delay periods attention effects, with significantly greater activity when attention included the RF * LFP showed increased coherence between MT and LIP in the ''spatial and feature'' and ''spatial'' attention conditions, particularly in the 10-35 Hz range; there is significantly less coherence when the S1 stimulus occurs outside the RF * Similarly, there is a significant (but weaker) coherence between LIP and MT spiking activity, seen in 34% of neuron pairs, with a phase shift suggesting that LIP leads MT in the ''spatial and feature'' and the ''spatial'' attention conditions * ''smaller effect expected given decreased likelihood of coupling when sampling pairs of neurons'' * Increased spike-field coherence within LIP in both spatial attention conditions compared to attention elsewhere suggests that synchronization within LIP may be important to increase downstream impact * Based on the apparent object feature selectivity (here for orientation), the authors suggest that LIP can, despite being in the dorsal stream, display feature selectivity (also see 'Gottlieb et al 1998':http://www.citeulike.org/user/klouie/article/90447 and 'Balan and Gottlieb 2006':http://www.citeulike.org/user/klouie/article/843521 ) and may mediate top-down attentional effects in object processing, either through direct connections to the ventral stream or gating V1 activity via MT AU - Saalmann, Yuri AU - Pigarev, Ivan AU - Vidyasagar, Trichur PY - 2007/06/15/ UR - http://dx.doi.org/10.1126/science.1139140 ER -