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

Trial paradigm.(A) A spatial layout of stimulus condition. A white cross indicates central fixation and the dashed white circle (invisible to the animal) represents the classical receptive field (RF). While the eye position was maintained within a window of 1 deg in radius centered about the fixation point, a static Gabor stimulus, S1, was first presented outside RF, and a second static Gabor stimulus, S2, was presented within RF. Both were presented for 20 ms each with a varying stimulus onset asynchrony (SOA), ranging from 0 to 100 ms. The animals’ task was to maintain central fixation and make a saccade following the target for liquid reward. (B) Temporal sequence of a trial.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3472985&req=5

pone-0047543-g002: Trial paradigm.(A) A spatial layout of stimulus condition. A white cross indicates central fixation and the dashed white circle (invisible to the animal) represents the classical receptive field (RF). While the eye position was maintained within a window of 1 deg in radius centered about the fixation point, a static Gabor stimulus, S1, was first presented outside RF, and a second static Gabor stimulus, S2, was presented within RF. Both were presented for 20 ms each with a varying stimulus onset asynchrony (SOA), ranging from 0 to 100 ms. The animals’ task was to maintain central fixation and make a saccade following the target for liquid reward. (B) Temporal sequence of a trial.

Mentions: The main experimental trial started with a beep. While central fixation was maintained within a 2-deg diameter circular criterion window centered on the fixation target, two identical circular Gabor stimuli were sequentially presented, each for 20 ms. The first stimulus (S1) was presented outside the RF and the second (S2) coincided with the RF (Fig. 2). Determination of the boundary between the RF center and surround is not simple [20], [23], [24]. To ensure that S1 did not encroach on the RF, we ensured that S1 did not evoke a spike response. The stimulus onset asynchrony (SOA) varied between 0 and 100 ms in steps of 10 ms. An SOA of 0 ms indicates simultaneous presentation of the two stimuli. To minimize saccade-related activity, the animal had to maintain central fixation for more than 300 ms before S1 onset.


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

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

Trial paradigm.(A) A spatial layout of stimulus condition. A white cross indicates central fixation and the dashed white circle (invisible to the animal) represents the classical receptive field (RF). While the eye position was maintained within a window of 1 deg in radius centered about the fixation point, a static Gabor stimulus, S1, was first presented outside RF, and a second static Gabor stimulus, S2, was presented within RF. Both were presented for 20 ms each with a varying stimulus onset asynchrony (SOA), ranging from 0 to 100 ms. The animals’ task was to maintain central fixation and make a saccade following the target for liquid reward. (B) Temporal sequence of a trial.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0047543-g002: Trial paradigm.(A) A spatial layout of stimulus condition. A white cross indicates central fixation and the dashed white circle (invisible to the animal) represents the classical receptive field (RF). While the eye position was maintained within a window of 1 deg in radius centered about the fixation point, a static Gabor stimulus, S1, was first presented outside RF, and a second static Gabor stimulus, S2, was presented within RF. Both were presented for 20 ms each with a varying stimulus onset asynchrony (SOA), ranging from 0 to 100 ms. The animals’ task was to maintain central fixation and make a saccade following the target for liquid reward. (B) Temporal sequence of a trial.
Mentions: The main experimental trial started with a beep. While central fixation was maintained within a 2-deg diameter circular criterion window centered on the fixation target, two identical circular Gabor stimuli were sequentially presented, each for 20 ms. The first stimulus (S1) was presented outside the RF and the second (S2) coincided with the RF (Fig. 2). Determination of the boundary between the RF center and surround is not simple [20], [23], [24]. To ensure that S1 did not encroach on the RF, we ensured that S1 did not evoke a spike response. The stimulus onset asynchrony (SOA) varied between 0 and 100 ms in steps of 10 ms. An SOA of 0 ms indicates simultaneous presentation of the two stimuli. To minimize saccade-related activity, the animal had to maintain central fixation for more than 300 ms before S1 onset.

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