Limits...
Modulation of V1 spike response by temporal interval of spatiotemporal stimulus sequence.

Kim T, Kim HR, Kim K, Lee C - PLoS ONE (2012)

Bottom Line: The spike activity of single neurons of the primary visual cortex (V1) becomes more selective and reliable in response to wide-field natural scenes compared to smaller stimuli confined to the classical receptive field (RF).This stimulus configuration enabled us to examine the spatiotemporal selectivity of response modulation from a focal surround region.These results suggest that V1 neurons participate in processing spatiotemporal sequences of oriented stimuli extending outside the RF.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Seoul National University, Kwanak, Seoul, Korea.

ABSTRACT
The spike activity of single neurons of the primary visual cortex (V1) becomes more selective and reliable in response to wide-field natural scenes compared to smaller stimuli confined to the classical receptive field (RF). However, it is largely unknown what aspects of natural scenes increase the selectivity of V1 neurons. One hypothesis is that modulation by surround interaction is highly sensitive to small changes in spatiotemporal aspects of RF surround. Such a fine-tuned modulation would enable single neurons to hold information about spatiotemporal sequences of oriented stimuli, which extends the role of V1 neurons as a simple spatiotemporal filter confined to the RF. In the current study, we examined the hypothesis in the V1 of awake behaving monkeys, by testing whether the spike response of single V1 neurons is modulated by temporal interval of spatiotemporal stimulus sequence encompassing inside and outside the RF. We used two identical Gabor stimuli that were sequentially presented with a variable stimulus onset asynchrony (SOA): the preceding one (S1) outside the RF and the following one (S2) in the RF. This stimulus configuration enabled us to examine the spatiotemporal selectivity of response modulation from a focal surround region. Although S1 alone did not evoke spike responses, visual response to S2 was modulated for SOA in the range of tens of milliseconds. These results suggest that V1 neurons participate in processing spatiotemporal sequences of oriented stimuli extending outside the RF.

Show MeSH

Related in: MedlinePlus

Response of another representative cell.(A) For this cell, S1 was presented at one of three locations, a–c, as shown along the axis collinear to that of RF orientation, with a spacing of one RF diameter. Some S1s encroached on the hemifield contralateral to RF. S1 orientation was collinear to S2. There were 33 unique stimulus sequences (3 S1 positions×11 SOAs), plus four single stimulus conditions at each S1 and S2 locations. These 37 stimulus conditions were randomly repeated within a block. (B) Spike activity with stimulation of S1 alone at locations, a–c. The cell remained silent with S1 at all tested locations. (C) Spike activity with S2 stimulus alone in raster and density (upper) and color (lower) plots. (D) SOA-time plots in the same format as Fig. 3D, for S1 at locations, a–c, from top to bottom. Color map of activity is shown to the right. Note a periodic SOA-dependency of activity modulation (E) Time course of significant modulation of spike response by sequence stimuli in the same format as Fig. 3F for S1 at locations, a–c, from top to bottom. Note that the activity modulation by the S1 at all locations was suppressive at virtually all SOAs. All the stimulus conditions of Fig. 5 were randomized within the same block during data collection.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3472985&req=5

pone-0047543-g005: Response of another representative cell.(A) For this cell, S1 was presented at one of three locations, a–c, as shown along the axis collinear to that of RF orientation, with a spacing of one RF diameter. Some S1s encroached on the hemifield contralateral to RF. S1 orientation was collinear to S2. There were 33 unique stimulus sequences (3 S1 positions×11 SOAs), plus four single stimulus conditions at each S1 and S2 locations. These 37 stimulus conditions were randomly repeated within a block. (B) Spike activity with stimulation of S1 alone at locations, a–c. The cell remained silent with S1 at all tested locations. (C) Spike activity with S2 stimulus alone in raster and density (upper) and color (lower) plots. (D) SOA-time plots in the same format as Fig. 3D, for S1 at locations, a–c, from top to bottom. Color map of activity is shown to the right. Note a periodic SOA-dependency of activity modulation (E) Time course of significant modulation of spike response by sequence stimuli in the same format as Fig. 3F for S1 at locations, a–c, from top to bottom. Note that the activity modulation by the S1 at all locations was suppressive at virtually all SOAs. All the stimulus conditions of Fig. 5 were randomized within the same block during data collection.

Mentions: Fig. 5 illustrates the activity of another representative V1 cell recorded during the task. For this cell, S1 was presented at one of three different locations, a through c, one to three diameters of RF away from the cell’s RF center along the axis collinear to the cell’s preferred orientation (Fig. 5A). The cell was recorded from the left V1 and its RF lay in the right visual space (dashed circle in Fig. 5A). With the stimulus configuration of Fig. 5A, some S1s were thus presented in the hemifield contralateral to RF, but perhaps partially overlapping with the strip of ipsilateral representation. The S1 alone at none of these positions evoked spike responses, confirming that these stimuli were presented outside the RF (Fig. 5B). The spike activity in response to presentation of S2 alone consisted of a transient increase and gradual decay (Fig. 5C). Although S1 alone did not evoke spike responses, presentation of S1 at any of these positions at the time of S2 presentation modulated the spike response at selective SOAs (Fig. 5D, E). The response modulation by S1 was mostly suppressive for the initial transient response during a poststimulus period of 50–150 ms and varied with the combination of SOA and S1 position. For example, S1 at the position a suppressed most strongly at the SOA of 50 ms, but at the same SOA, S1 at b or c did not suppress as much. Note that this SOA-dependency is a property of V1 cells encompassing both spatial regions inside and outside RF, thus separate from motion tuning or directional selectivity confined within RF.


Modulation of V1 spike response by temporal interval of spatiotemporal stimulus sequence.

Kim T, Kim HR, Kim K, Lee C - PLoS ONE (2012)

Response of another representative cell.(A) For this cell, S1 was presented at one of three locations, a–c, as shown along the axis collinear to that of RF orientation, with a spacing of one RF diameter. Some S1s encroached on the hemifield contralateral to RF. S1 orientation was collinear to S2. There were 33 unique stimulus sequences (3 S1 positions×11 SOAs), plus four single stimulus conditions at each S1 and S2 locations. These 37 stimulus conditions were randomly repeated within a block. (B) Spike activity with stimulation of S1 alone at locations, a–c. The cell remained silent with S1 at all tested locations. (C) Spike activity with S2 stimulus alone in raster and density (upper) and color (lower) plots. (D) SOA-time plots in the same format as Fig. 3D, for S1 at locations, a–c, from top to bottom. Color map of activity is shown to the right. Note a periodic SOA-dependency of activity modulation (E) Time course of significant modulation of spike response by sequence stimuli in the same format as Fig. 3F for S1 at locations, a–c, from top to bottom. Note that the activity modulation by the S1 at all locations was suppressive at virtually all SOAs. All the stimulus conditions of Fig. 5 were randomized within the same block during data collection.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3472985&req=5

pone-0047543-g005: Response of another representative cell.(A) For this cell, S1 was presented at one of three locations, a–c, as shown along the axis collinear to that of RF orientation, with a spacing of one RF diameter. Some S1s encroached on the hemifield contralateral to RF. S1 orientation was collinear to S2. There were 33 unique stimulus sequences (3 S1 positions×11 SOAs), plus four single stimulus conditions at each S1 and S2 locations. These 37 stimulus conditions were randomly repeated within a block. (B) Spike activity with stimulation of S1 alone at locations, a–c. The cell remained silent with S1 at all tested locations. (C) Spike activity with S2 stimulus alone in raster and density (upper) and color (lower) plots. (D) SOA-time plots in the same format as Fig. 3D, for S1 at locations, a–c, from top to bottom. Color map of activity is shown to the right. Note a periodic SOA-dependency of activity modulation (E) Time course of significant modulation of spike response by sequence stimuli in the same format as Fig. 3F for S1 at locations, a–c, from top to bottom. Note that the activity modulation by the S1 at all locations was suppressive at virtually all SOAs. All the stimulus conditions of Fig. 5 were randomized within the same block during data collection.
Mentions: Fig. 5 illustrates the activity of another representative V1 cell recorded during the task. For this cell, S1 was presented at one of three different locations, a through c, one to three diameters of RF away from the cell’s RF center along the axis collinear to the cell’s preferred orientation (Fig. 5A). The cell was recorded from the left V1 and its RF lay in the right visual space (dashed circle in Fig. 5A). With the stimulus configuration of Fig. 5A, some S1s were thus presented in the hemifield contralateral to RF, but perhaps partially overlapping with the strip of ipsilateral representation. The S1 alone at none of these positions evoked spike responses, confirming that these stimuli were presented outside the RF (Fig. 5B). The spike activity in response to presentation of S2 alone consisted of a transient increase and gradual decay (Fig. 5C). Although S1 alone did not evoke spike responses, presentation of S1 at any of these positions at the time of S2 presentation modulated the spike response at selective SOAs (Fig. 5D, E). The response modulation by S1 was mostly suppressive for the initial transient response during a poststimulus period of 50–150 ms and varied with the combination of SOA and S1 position. For example, S1 at the position a suppressed most strongly at the SOA of 50 ms, but at the same SOA, S1 at b or c did not suppress as much. Note that this SOA-dependency is a property of V1 cells encompassing both spatial regions inside and outside RF, thus separate from motion tuning or directional selectivity confined within RF.

Bottom Line: The spike activity of single neurons of the primary visual cortex (V1) becomes more selective and reliable in response to wide-field natural scenes compared to smaller stimuli confined to the classical receptive field (RF).This stimulus configuration enabled us to examine the spatiotemporal selectivity of response modulation from a focal surround region.These results suggest that V1 neurons participate in processing spatiotemporal sequences of oriented stimuli extending outside the RF.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Seoul National University, Kwanak, Seoul, Korea.

ABSTRACT
The spike activity of single neurons of the primary visual cortex (V1) becomes more selective and reliable in response to wide-field natural scenes compared to smaller stimuli confined to the classical receptive field (RF). However, it is largely unknown what aspects of natural scenes increase the selectivity of V1 neurons. One hypothesis is that modulation by surround interaction is highly sensitive to small changes in spatiotemporal aspects of RF surround. Such a fine-tuned modulation would enable single neurons to hold information about spatiotemporal sequences of oriented stimuli, which extends the role of V1 neurons as a simple spatiotemporal filter confined to the RF. In the current study, we examined the hypothesis in the V1 of awake behaving monkeys, by testing whether the spike response of single V1 neurons is modulated by temporal interval of spatiotemporal stimulus sequence encompassing inside and outside the RF. We used two identical Gabor stimuli that were sequentially presented with a variable stimulus onset asynchrony (SOA): the preceding one (S1) outside the RF and the following one (S2) in the RF. This stimulus configuration enabled us to examine the spatiotemporal selectivity of response modulation from a focal surround region. Although S1 alone did not evoke spike responses, visual response to S2 was modulated for SOA in the range of tens of milliseconds. These results suggest that V1 neurons participate in processing spatiotemporal sequences of oriented stimuli extending outside the RF.

Show MeSH
Related in: MedlinePlus