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Cited by 360Visual perception and processing mechanismsNeural and Behavioral Psychology StudiesNeural dynamics and brain function

Microstimulation of macaque area LIP affects decision-making in a motion discrimination task

Open access
Hanks, Timothy D, Ditterich, Jochen, Shadlen, Michael N·2006·Nature Neuroscience
DOI 10.1038/nn1683PMC PMC2770004
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Abstract

A central goal of cognitive neuroscience is to elucidate the neural mechanisms underlying decision-making. Recent physiological studies suggest that neurons in association areas may be involved in this process. To test this, we measured the effects of electrical microstimulation in the lateral intraparietal area (LIP) while monkeys performed a reaction-time motion discrimination task with a saccadic response. In each experiment, we identified a cluster of LIP cells with overlapping response fields (RFs) and sustained activity during memory-guided saccades. Microstimulation of this cluster caused an increase in the proportion of choices toward the RF of the stimulated neurons. Choices toward the stimulated RF were faster with microstimulation, while choices in the opposite direction were slower. Microstimulation never directly evoked saccades, nor did it change reaction times in a simple saccade task. These results demonstrate that the discharge of LIP neurons is causally related to decision formation in the discrimination task.

AI snapshot

Written from the paper’s full text.

TL;DR

Microstimulation of macaque LIP clusters whose response fields overlapped a choice target biased decisions toward that target and changed reaction times during a reaction-time motion discrimination task. The pattern was best explained by an offset in the accumulated decision variable, not by a change in momentary sensory evidence, and control saccade trials showed no direct saccade evocation or generic motor slowing.

Key findings

  • Across 24 LIP sites (12 per monkey), microstimulation increased choices toward the target in the stimulated neurons’ RF (Tin) in 17/24 sites. The choice bias was equivalent to adding 2.13% coherent motion toward Tin for monkey B (95% CI 1.42–2.85% coh, P < 0.001) and 1.00% coh for monkey S (CI 0.32–1.68% coh, P < 0.005).
  • Microstimulation reduced RTs for Tin choices (monkey B: equivalent to 4.26% coh toward Tin, CI 2.04–6.49% coh, P < 0.005; monkey S: 1.71% coh, CI 0.39–3.04% coh, P < 0.05) and increased RTs for Tout choices (monkey B: equivalent to 7.70% coh toward Tin, CI 5.28–10.13% coh, P < 0.001; monkey S: 1.60% coh, CI 0.33–2.87% coh, P < 0.05). Tin RTs decreased in 16/24 sites; Tout RTs increased in 23/24 sites.
  • In interleaved delayed-saccade control trials, microstimulation never evoked saccades and did not affect response latency (Tin: +1.4 ± 1.6 ms, P = 0.4; Tout: +0.7 ± 1.5 ms, P = 0.6; mean ± SEM, n = 19 sites, 2,550 trials; mean RT 221 ms).
  • Diffusion-to-bound modeling indicated LIP stimulation was best accounted for by an offset in the decision variable (monkey B: 16.9% of the bound, CI 11.4–22.3%; monkey S: 4.7%, CI 0.6–8.8%), with negligible change in momentary evidence. By contrast, MT stimulation was best accounted for as a change in momentary evidence equivalent to 9.3% coh (CI 7.8–10.8% coh), with negligible decision-variable offset.

Methods

  • Two rhesus monkeys performed a reaction-time two-choice direction discrimination task with random-dot motion, indicating choice by saccade to one of two targets. One target (Tin) was in the LIP multiunit RF; the other target (Tout) and the motion stimulus were outside the RF.
  • Microstimulation (10–20 µA biphasic pulses, 300 µs duration, 200 Hz) was applied during motion viewing on a random half of trials and terminated at saccade initiation. Control delayed-saccade trials were interleaved.
  • 24 LIP sites (12 per monkey) were selected for overlapping RFs and sustained delay-period activity. Choice data were analyzed with logistic regression; RT data with line fits; and a diffusion-to-bound model was fit to compare LIP and MT microstimulation effects.

Limitations

  • The paper states that LIP–MT comparisons are limited by different experimental designs: MT experiments stimulated neurons with RFs overlapping the motion stimulus, whereas LIP experiments stimulated neurons with RFs overlapping a choice target. It also notes variability in baseline behavior between animals and across experiments.
  • The paper states that the quantitative prediction exercise is speculative, relies on assumptions and simplifications, and that monkey S lacked LIP recording and MT microstimulation data. It also notes that antidromic activation of other areas cannot be ruled out.
  • Evident from the text: the study used only two monkeys, the behavioral effects were modest, and some descriptive fits showed systematic error. The spread of microstimulation is also uncertain because direct activation is estimated within ~100 µm but indirect activation may increase spread.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/nn1683

Cites

51 of 51 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 46 cited sources checked · 0 supported · 0 flagged

  • Findingown data
    § Abstract

    Microstimulation did not change reaction times in a simple saccade task.

    “nor did it change reaction times in a simple saccade task.”
    • Also stated in: § RESULTS · plain
      “the latencies of the motor responses in the control trials were not affected by microstimulation (Tin: RT increased 1.4 ± 1.6 ms, P = 0.4; Tout: RT increased 0.7 ± 1.5 ms, P = 0.6; mean ± SEM, n = 19 sites, 2,550 trials; mean RT: 221 ms).”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    Microstimulation reduced reaction times for choices toward the stimulated response field (Tin choices).

    “Choices toward the stimulated RF were faster with microstimulation”
    • Also stated in: § RESULTS · plain
      “The first effect of microstimulation on decision time was a reduction in RT for Tin choices (Fig. 2c,d, solid circles).”
    Quote in the paperSubstantial claim
  • Findingown data
    § RESULTS

    For monkey B, LIP microstimulation biased decisions in favor of Tin by an amount equivalent to adding 2.13% coherent motion toward Tin (95% CI: 1.42 to 2.85% coh, P < 0.001).

    “For monkey B, LIP microstimulation biased decisions in favor of Tin by an amount equivalent to adding 2.13% coherent motion toward Tin (95% CI: 1.42 to 2.85% coh, P < 0.001).”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    Microstimulation of a cluster of LIP cells with overlapping response fields caused an increase in the proportion of choices to the response field of the stimulated neurons.

    “Microstimulation of this cluster caused an increase in the proportion of choices to the RF of the stimulated neurons.”
    • Also stated in: § RESULTS · plain
      “Microstimulation biased the monkeys to choose the direction of motion associated with the Tin choice target (Fig. 2a,b).”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    Microstimulation increased reaction times for choices in the direction opposite the stimulated response field (Tout choices).

    “while choices in the opposite direction were slower.”
    • Also stated in: § RESULTS · plain
      “The second effect of microstimulation on decision time was an increase in RT for Tout choices (Fig. 2c,d, solid squares).”
    Quote in the paperSubstantial claim
  • May combine two claims. 26
  • Classified as probably not a substantial claim. 40

  • May combine two claims.

    Findingown data
    § RESULTS

    Microstimulation caused a small change in choice frequencies, most apparent at weaker motion strengths.

    “Microstimulation caused a small change in these choice frequencies. This was most apparent at the weaker motion strengths (the middle of the plot), where stimulation caused an increase in Tin choices at nearly every point for both monkeys.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation
    § RESULTS

    On both stimulation and non-stimulation trials, stronger motion toward Tin led to more Tin choices, and stronger motion toward Tout led to more Tout choices.

    “On both stimulation and non-stimulation trials, stronger motion toward Tin led to more Tin choices, and stronger motion toward Tout led to more Tout choices, as previously shown10.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] Roitman, J.D. & Shadlen, M.N. Response of neurons in the lateral intraparietal area during a combined visual discrimination reaction time task. J. Neurosci. 22, 9475–9489 (2002). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation
    § RESULTS

    On both stimulation and non-stimulation trials, stronger motion led to faster reaction times for both Tin and Tout choices compared to more difficult conditions.

    “On both stimulation and non-stimulation trials, stronger motion led to faster RTs for both Tin and Tout choices, compared to the more difficult conditions, as has been previously shown10.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] Roitman, J.D. & Shadlen, M.N. Response of neurons in the lateral intraparietal area during a combined visual discrimination reaction time task. J. Neurosci. 22, 9475–9489 (2002). source

      Not checked in the free run.

  • May combine two claims.

    Findingown data
    § RESULTS

    Overall, the effects of LIP microstimulation were modest but consistent across the 24 sites.

    “Overall, the effects of LIP microstimulation were modest but consistent across the 24 sites (Fig. 3).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § RESULTS

    In 17/24 sites, microstimulation increased the probability of Tin choices, and only one site showed a substantial increase in Tout choices.

    “In 17/24 sites, microstimulation increased the probability of Tin choices, and there was only one site in which microstimulation caused a substantial increase in Tout choices.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § RESULTS

    The effects of microstimulation on choice and reaction time were only weakly correlated, with no pairwise correlation statistically significant in either animal individually (P > 0.2; Fisher z).

    “These effects were only weakly correlated with each other: no pairwise correlation was statistically significant in either animal individually (P > 0.2; Fisher z).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § RESULTS

    LIP stimulation led to relatively small changes in reaction time and choice, especially choice.

    “The most obvious difference is that LIP stimulation led to relatively small changes in RT and choice, especially the latter (Fig. 4).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § RESULTS

    Stimulation caused the monkeys to decrease reaction times for Tin choices in 16/24 sites and to increase reaction times for Tout choices in 23/24 sites.

    “Moreover, stimulation caused the monkeys to decrease their RTs when making decisions in favor of Tin in 16/24 sites and to increase their RTs for Tout choices in 23/24 sites.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § RESULTS

    LIP stimulation has a greater average effect on reaction time than on choice, in contrast to the effects of MT stimulation.

    “LIP stimulation has a greater average effect on RT than on choice, in contrast to the effects of MT stimulation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § RESULTS

    The model fits indicate that MT stimulation did not affect the accumulated evidence: the estimated offset of the decision variable was negligible and in the opposite direction as the stimulation effects (mean: −1.2% of the bound, CI: −5.3 to 2.9%).

    “The model fits also indicate that MT stimulation did not affect the accumulated evidence: the estimated offset of the decision variable was negligible and in the opposite direction as the stimulation effects (mean: −1.2% of the bound, CI: −5.3 to 2.9%).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Microstimulation of LIP neurons can be modeled as adding to the momentary evidence or the accumulated decision variable (or both).

  • May combine two claims.

    Findingown data
    § RESULTS

    For monkey S, the change in the momentary evidence was negligible and in the opposite direction as the stimulation effects (mean: −0.29% coh, CI: −1.11 to 0.53% coh).

    “The change in the momentary evidence was negligible and in the opposite direction as the stimulation effects (mean: −0.29% coh, CI: −1.11 to 0.53% coh).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Microstimulation of LIP neurons can be modeled as adding to the momentary evidence or the accumulated decision variable (or both).

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data
    § RESULTS

    These predictions also match the data reasonably well.

    “These predictions also match the data reasonably well (Fig. 6b).”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The higher diffusion bound in monkey S is instantiated as a higher neural bound in LIP.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given
    § METHODS

    All stimulation sites exhibited sustained responses during memory saccade trials.

    “All stimulation sites also exhibited sustained responses during memory saccade trials.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given
    § METHODS

    There was never any discernable modulation when a target was placed at the location of the motion stimulus or at the Tout location.

    “Specifically, there was never any discernable modulation when a target was placed at the location of the motion stimulus or at the Tout location.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data
    § METHODS

    We did detect subtle changes in saccade metrics with microstimulation for some experiments.

    “we did detect subtle changes in saccade metrics with microstimulation for some experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given
    § METHODS

    The RT asymmetry in monkey B for the non-stimulation trials provides a particularly striking example.

    “The RT asymmetry in monkey B for the non-stimulation trials provides a particularly striking example.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § RESULTS

    According to the diffusion-to-bound framework, motion-selective neurons in MT provide the momentary evidence that is accumulated into the decision variable represented by neurons in LIP.

    “According to this framework, motion-selective neurons in MT provide the momentary evidence that is accumulated into the decision variable represented by neurons in LIP.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [10] Roitman, J.D. & Shadlen, M.N. Response of neurons in the lateral intraparietal area during a combined visual discrimination reaction time task. J. Neurosci. 22, 9475–9489 (2002). source

      Not checked in the free run.

    • cites [16] Ditterich, J., Mazurek, M. & Shadlen, M.N. Microstimulation of visual cortex affects the speed of perceptual decisions. Nat. Neurosci. 6, 891–898 (2003). source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning
    § RESULTS

    A change in the firing rates of LIP neurons brings the decision variable closer to the bound, but the effect is not cumulative.

    “In contrast, a change in the firing rates of the LIP neurons brings the decision variable closer to the bound, but the effect is not cumulative.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § RESULTS

    Based on recordings from MT of other monkeys, a change in motion strength of 10% coherence results in a change in firing rate of 5 sp/s for the average MT neuron.

    “Based on recordings from MT of other monkeys, a change in motion strength of 10% coherence results in a change in firing rate of 5 sp/s for the average MT neuron15.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [15] Britten, K.H., Shadlen, M.N., Newsome, W.T. & Movshon, J.A. Responses of neurons in macaque MT to stochastic motion signals. Vis. Neurosci. 10, 1157–1169 (1993). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § RESULTS

    The same numerical exercise also plausibly explains the smaller effects of LIP stimulation in monkey S.

    “The same exercise also plausibly explains the smaller effects of LIP stimulation in monkey S.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: In the numerical exercise, microstimulation affects LIP similarly to MT, adding about 5 sp/s to LIP firing rate.

  • May combine two claims.

    Interpretationreasoning
    § RESULTS

    Comparisons between LIP and MT stimulation are limited by the experimental design and by variability in baseline behavior between animals and across experiments.

    “Of course, it should be noted that these comparisons are limited by the experimental design (stimulating a cluster of cells with RFs overlapping the motion stimulus for the MT experiment versus a cluster of cells with RFs overlapping one of the targets for the LIP experiment) and variability in baseline behavior between animals and across experiments.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § DISCUSSION

    Previous applications of microstimulation to area LIP have led to the idea that this area plays a role in the timing of saccades but not to eye movement selection.

    “Previous applications of microstimulation to area LIP have led to the idea that this area plays a role in the timing of saccades but not to eye movement selection31.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [31] Schiller, P.H. & Tehovnik, E.J. Look and see: how the brain moves your eyes about. Prog. Brain Res. 134, 127–142 (2001). source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning
    § DISCUSSION

    These LIP neurons most likely play this role because decisions about motion are, in this task, decisions about where to move the eyes.

    “These LIP neurons most likely play this role because decisions about motion are, in our task, decisions about where to move the eyes.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § DISCUSSION

    MT neurons have been shown to play a causal role in the perceptual judgment of visual motion in their receptive fields.

    “This puts LIP neurons on similar footing to MT neurons, which have been shown to play a causal role in the perceptual judgment of visual motion in their receptive fields7,16,23.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [7] Salzman, C.D., Murasugi, C.M., Britten, K.H. & Newsome, W.T. Microstimulation in visual area MT: effects on direction discrimination performance. J. Neurosci. 12, 2331–2355 (1992). source

      Not checked in the free run.

    • cites [16] Ditterich, J., Mazurek, M. & Shadlen, M.N. Microstimulation of visual cortex affects the speed of perceptual decisions. Nat. Neurosci. 6, 891–898 (2003). source

      Not checked in the free run.

    • cites [23] Bisley, J.W., Zaksas, D. & Pasternak, T. Microstimulation of cortical area MT affects performance on a visual working memory task. J. Neurophysiol. 85, 187–196 (2001). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § DISCUSSION

    Previous single-unit recording studies suggest that many LIP neurons accumulate evidence over time from sensory areas such as MT to a criterion level in order to form a decision.

    “It also complements previous results from single-unit recording studies that suggest that many LIP neurons accumulate evidence over time from sensory areas such as MT to a criterion level in order to form a decision10.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] Roitman, J.D. & Shadlen, M.N. Response of neurons in the lateral intraparietal area during a combined visual discrimination reaction time task. J. Neurosci. 22, 9475–9489 (2002). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § RESULTS

    If the higher bound is instantiated as a higher neural bound in LIP, then smaller shifts in the psychometric and chronometric functions are expected for the same 5 sp/s change in the decision variable.

    “If the higher bound is instantiated as a higher neural bound in LIP, then smaller shifts in the psychometric and chronometric functions are expected for the same 5 sp/s change in the decision variable.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The higher diffusion bound in monkey S is instantiated as a higher neural bound in LIP.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § DISCUSSION

    The superior colliculus is known to play a causal role in the selection of targets for eye movements.

    “and the superior colliculus is also known to play a causal role in the selection of targets for eye movements38.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Carello, C.D. & Krauzlis, R.J. Manipulating intent: evidence for a causal role of the superior colliculus in target selection. Neuron 43, 575–583 (2004). source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Interpretationreasoning
    § DISCUSSION

    According to the diffusion-to-bound model, the slowing is produced by raising the bound of the competing mechanism, or equivalently by subtracting from the accumulation of evidence.

    “According to the diffusion-to-bound model, the slowing is produced by raising the bound of the competing mechanism, or equivalently by subtracting from the accumulation of evidence.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The momentary evidence in the diffusion model is drawn from a unit-variance Gaussian distribution with mean μ determined by a linear transform of the motion strength.
    • The authors state this as an assumption: The total RT is a combination of the decision time and a nondecision residual time that accounts for sensory and motor latencies and presumably involves other processes that are not fully understood.
    • The authors state this as an assumption: In the absence of stimulation, the diffusion model bounds are symmetric (B = A).

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § DISCUSSION

    Several other brain structures such as the superior colliculus, the dorsolateral prefrontal cortex (Walker area 46), and the FEF are thought to represent quantities like the accumulated evidence in area LIP.

    “Several other brain structures such as the superior colliculus, the dorsolateral prefrontal cortex (Walker area 46), and the FEF are thought to represent quantities like the accumulated evidence in area LIP2,10,11,34–37”
    Quote in the paperNot a substantial claim0 of 7 sources checked
    • cites [2] Schall, J. & Thompson, K. Neural selection and control of visually guided eye movements. Annu. Rev. Neurosci. 22, 241–259 (1999). source

      Not checked in the free run.

    • cites [10] Roitman, J.D. & Shadlen, M.N. Response of neurons in the lateral intraparietal area during a combined visual discrimination reaction time task. J. Neurosci. 22, 9475–9489 (2002). source

      Not checked in the free run.

    • cites [11] Shadlen, M.N. & Newsome, W.T. Neural basis of a perceptual decision in the parietal cortex (area LIP) of the rhesus monkey. J. Neurophysiol. 86, 1916–1936 (2001). source

      Not checked in the free run.

    • cites [34] Romo, R., Hernandez, A. & Zainos, A. Neuronal correlates of a perceptual decision in ventral premotor cortex. Neuron 41, 165–173 (2004). source

      Not checked in the free run.

    • cites [35] Kim, J.-N. & Shadlen, M.N. Neural correlates of a decision in the dorsolateral prefrontal cortex of the macaque. Nat. Neurosci. 2, 176–185 (1999). source

      Not checked in the free run.

    • cites [36] Horwitz, G.D. & Newsome, W.T. Target selection for saccadic eye movements: prelude activity in the superior colliculus during a direction-discrimination task. J. Neurophysiol. 86, 2543–2558 (2001). source

      Not checked in the free run.

    • cites [37] Huk, A.C. & Shadlen, M.N. Neural activity in macaque parietal cortex reflects temporal integration of visual motion signals during perceptual decision making. J. Neurosci. 25, 10420–10436 (2005). source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductreasoning
    § DISCUSSION

    The combined choice-reaction time paradigm provides a sensitive measure (RT) and permits application of microstimulation during the prolonged period of decision formation that can be identified on each trial.

    “In addition to providing a sensitive measure (RT), it permits application of microstimulation during the rather prolonged period of decision formation that could be identified on each trial.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § DISCUSSION

    Previous studies have shown that LIP responses are modulated by many factors, such as attention, expectation, time, motor intention, experienced value, reward, and the prior probability of making an eye movement.

    “In addition, previous studies have shown that LIP responses are modulated by many factors, such as attention, expectation, time, motor intention, experienced value, reward, and the prior probability of making an eye movement12,13,39–42.”
    Quote in the paperNot a substantial claim0 of 6 sources checked
    • cites [12] Colby, C.L. & Goldberg, M.E. Space and attention in parietal cortex. Annu. Rev. Neurosci. 22, 319–349 (1999). source

      Not checked in the free run.

    • cites [13] Andersen, R.A. & Buneo, C.A. Intentional maps in posterior parietal cortex. Annu. Rev. Neurosci. 25, 189–220 (2002). source

      Not checked in the free run.

    • cites [39] Eskandar, E.N. & Assad, J.A. Dissociation of visual, motor and predictive signals in parietal cortex during visual guidance. Nat. Neurosci. 2, 88–93 (1999). source

      Not checked in the free run.

    • cites [40] Leon, M.I. & Shadlen, M.N. Representation of time by neurons in the posterior parietal cortex of the macaque. Neuron 38, 317–327 (2003). source

      Not checked in the free run.

    • cites [41] Sugrue, L.P., Corrado, G.S. & Newsome, W.T. Matching behavior and the representation of value in the parietal cortex. Science 304, 1782–1787 (2004). source

      Not checked in the free run.

    • cites [42] Platt, M.L. & Glimcher, P.W. Neural correlates of decision variables in parietal cortex. Nature 400, 233–238 (1999). source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductnone given
    § METHODS

    The time between target onset and the go signal was set so that the average duration of microstimulation was roughly equal in control trials to that applied during the discrimination trials.

    “The time between target onset and the go signal was set so that the average duration of microstimulation was roughly equal in control trials to that applied during the discrimination trials.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given
    § METHODS

    All training, surgery and experimental procedures were in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and were approved by the University of Washington Animal Care Committee.

    “All training, surgery and experimental procedures were in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and were approved by the University of Washington Animal Care Committee.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § METHODS

    The MT data are from a previously published study and incorporate two additional sites acquired after publication.

    “The MT data (Fig. 4 and Fig 5) are from a previously published study16 and incorporate two additional sites acquired after publication.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] Ditterich, J., Mazurek, M. & Shadlen, M.N. Microstimulation of visual cortex affects the speed of perceptual decisions. Nat. Neurosci. 6, 891–898 (2003). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § METHODS

    Stimulation levels of 10-20 μA biphasic current pulses of 300 μs duration at 200 Hz are thought to directly activate neurons within an approximately 100 μm radius of the electrode tip, but indirect activation of neural elements may increase this spread.

    “These levels are thought to directly activate neurons within an approximately 100 µm radius of the electrode tip46, but indirect activation of neural elements may increase this spread47.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [46] Tehovnik, E.J. Electrical stimulation of neural tissue to evoke behavioral responses. J. Neurosci. Methods 65, 1–17 (1996). source

      Not checked in the free run.

    • cites [47] Butovas, S. & Schwarz, C. Spatiotemporal effects of microstimulation in rat neocortex: a parametric study using multielectrode recordings. J. Neurophysiol. 90, 3024–3039 (2003). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given
    § METHODS

    We preset the minimum number of discrimination trials for including data at 500, and we always stopped collecting data after 800-900 discrimination trials.

    “We preset the minimum number of discrimination trials for including data at 500, and we always stopped collecting data after 800–900 discrimination trials.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given
    § METHODS

    We applied microstimulation during the entire duration of the motion stimulus on a randomly chosen half of the trials.

    “We applied microstimulation during the entire duration of the motion stimulus on a randomly chosen half of the trials.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data
    § METHODS

    The multiunit RFs were typically 9° eccentric (range 5° to 15°) and did not overlap the random dot motion stimulus.

    “RFs were typically 9° eccentric (range 5° to 15°) and did not overlap the random dot motion stimulus.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given
    § METHODS

    We only performed one experiment at any particular stimulation site, so that each site corresponds to a unique location within LIP.

    “We only performed one experiment at any particular stimulation site, so that each site corresponds to a unique location within LIP.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § METHODS

    The MT stimulation study to which we compare our data used the same stimulation protocol, except the amplitude of the current pulses was 5 μA.

    “The MT stimulation study to which we compare our data used the same stimulation protocol, except the amplitude of the current pulses was 5 µA16.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] Ditterich, J., Mazurek, M. & Shadlen, M.N. Microstimulation of visual cortex affects the speed of perceptual decisions. Nat. Neurosci. 6, 891–898 (2003). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning
    § METHODS

    We include all stimulation sites from the MT study here in order to provide a fair comparison with the LIP results.

    “We include all stimulation sites from the MT study here in order to provide a fair comparison with the LIP results.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning
    § METHODS

    Near C=0, the decision time varies linearly as a function of C and approximately quadratically as a function of the criterion height (A+B).

    “Notice that near C=0, the decision time varies linearly as a function of C and approximately quadratically as a function of the criterion height (A+B).”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The momentary evidence in the diffusion model is drawn from a unit-variance Gaussian distribution with mean μ determined by a linear transform of the motion strength.
    • The authors state this as an assumption: The total RT is a combination of the decision time and a nondecision residual time that accounts for sensory and motor latencies and presumably involves other processes that are not fully understood.
    • The authors state this as an assumption: In the absence of stimulation, the diffusion model bounds are symmetric (B = A).

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given
    § METHODS

    Adding a fixed offset to the decision variable is formally equivalent to subtracting a constant from the bounds.

    “Adding a fixed offset to the decision variable is formally equivalent to subtracting a constant from the bounds.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given
    § METHODS

    The diffusion model is formally equivalent to a race between competing accumulators when the accumulated quantities (e.g., evidence for left vs. right) are anticorrelated.

    “Note that the diffusion model is formally equivalent to a race between competing accumulators when the accumulated quantities (e.g., evidence for left vs. right) are anticorrelated.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisereasoning
    § METHODS

    Increasing the decision variable by one unit can be implemented in the above equations by making A one unit smaller and B one unit larger.

    “Thus, increasing the decision variable by one unit can be implemented in the above equations by making A one unit smaller and B one unit larger.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given
    § METHODS

    Sites for microstimulation were selected based on a consistent location of the multi-unit RF over a span of at least 200 μm, and the electrode was placed in the middle of the cluster.

    “Sites for microstimulation were selected based on a consistent location of the multi-unit RF over a span of at least 200 µm, and the electrode was placed in the middle of the cluster.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § METHODS

    The previous MT study was focused on stimulation-induced changes in RT in an area already known to affect choice in this paradigm.

    “The goals of the present study differs from the previous one, which was focused on stimulation-induced changes in RT in an area already known to affect choice in this paradigm7.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [7] Salzman, C.D., Murasugi, C.M., Britten, K.H. & Newsome, W.T. Microstimulation in visual area MT: effects on direction discrimination performance. J. Neurosci. 12, 2331–2355 (1992). source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation
    § METHODS

    The expected difference in firing rates between direction selective neurons in area MT is zero when C=0 and is known to vary linearly, on average, as a function of motion strength.

    “This relationship is reasonable because the expected difference in firing rates between direction selective neurons in area MT is zero when C=0 and is known to vary linearly, on average, as a function of motion strength15.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [15] Britten, K.H., Shadlen, M.N., Newsome, W.T. & Movshon, J.A. Responses of neurons in macaque MT to stochastic motion signals. Vis. Neurosci. 10, 1157–1169 (1993). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § METHODS

    Analytic solutions exist for the probability of hitting bound A first and the mean time to bound A in the diffusion model.

    “One advantage of this model is that analytic solutions exist for both of these22,49.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [22] Palmer, J., Huk, A.C. & Shadlen, M.N. The effect of stimulus strength on the speed and accuracy of a perceptual decision. J. Vis. 5, 376–404 (2005). source

      Not checked in the free run.

    • cites [49] Smith, P. A note on the distribution of response times for a random walk with gaussian increments. J. Math. Psychol. 34, 445–459 (1990). source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductnone given
    § METHODS

    The rules governing reward were not altered on microstimulation trials.

    “The rules governing reward were not altered on microstimulation trials.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § METHODS

    Experiments were never stopped prematurely unless the monkey refused to continue.

    “When a site was found, experiments were never stopped prematurely unless the monkey refused to continue.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductown data
    § METHODS

    We retested the stimulation effects after incorporating additional terms for saccade duration, mean velocity, peak velocity, and distance of saccade in equations 1 and 2 to test whether changes in saccade metrics could account for the observed effects of microstimulation.

    “To test whether these changes in saccade metrics could account for the observed effects of microstimulation, we retested the stimulation effects after incorporating additional terms for saccade duration, mean velocity, peak velocity, and distance of saccade in equations 1 and 2.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning
    § METHODS

    Our figures and analyses incorporate all MT sites, including those without significant choice effects.

    “Unlike the previous study, our figures and analyses incorporate all MT sites, including those without significant choice effects.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § METHODS

    Both the momentary evidence and the decision variable of the diffusion model can be related to neural responses.

    “Both the momentary evidence and the decision variable of this model can be related to neural responses18.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [18] Mazurek, M.E., Roitman, J.D., Ditterich, J. & Shadlen, M.N. A role for neural integrators in perceptual decision making. Cereb. Cortex 13, 1257–1269 (2003). source

      Not checked in the free run.

54 of 54

  • The authors state this as an assumption.

    Microstimulation of LIP neurons can be modeled as adding to the momentary evidence or the accumulated decision variable (or both).

    “We therefore solved for the diffusion-to-bound model that best explained the effect of microstimulation of MT and LIP in monkey B by assuming that stimulation added to the momentary evidence or the decision variable or both (see Methods).”

  • The authors state this as an assumption.

    In the numerical exercise, microstimulation affects LIP similarly to MT, adding about 5 sp/s to LIP firing rate.

    “Suppose then that microstimulation were to affect LIP similarly to MT.”
    “If microstimulation adds 5 sp/s to the average firing rate of LIP neurons with the Tin target in their RF, it would be equivalent to a change in the starting point of the accumulation by 18.5% of the overall excursion.”

  • The authors state this as an assumption.

    The higher diffusion bound in monkey S is instantiated as a higher neural bound in LIP.

    “If the higher bound is instantiated as a higher neural bound in LIP, then smaller shifts in the psychometric and chronometric functions are expected for the same 5 sp/s change in the decision variable.”

  • The authors state this as an assumption.

    The momentary evidence in the diffusion model is drawn from a unit-variance Gaussian distribution with mean μ determined by a linear transform of the motion strength.

    “The momentary evidence gathered in each time step is drawn from a unit-variance Gaussian distribution with mean μ determined by a linear transform of the motion strength:”

  • The authors state this as an assumption.

    The total RT is a combination of the decision time and a nondecision residual time that accounts for sensory and motor latencies and presumably involves other processes that are not fully understood.

    “The total RT is a combination of the decision time and a nondecision “residual” time, which accounts for sensory and motor latencies and presumably involves other processes that we do not fully understand37.”

  • The authors state this as an assumption.

    In the absence of stimulation, the diffusion model bounds are symmetric (B = A).

    “We always assumed symmetric bounds in the absence of stimulation so that B = A.”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • This accumulation is encoded in the firing rates of LIP neurons with response fields aligned to the choice targets representing the direction alternatives.

    “This accumulation is encoded in the firing rates of LIP neurons with response fields aligned to the choice targets representing the direction alternatives (18, 55–57).”

    From Representation of Confidence Associated with a Decision by Neurons in the Parietal Cortex (2009) · cites this paper as [55]

  • The present results show that the same neurons that participate in decision formation carry the relevant signals for assigning the probability of obtaining a reward.

    “The present results show that the same neurons that participate in decision formation (20, 55) carry the relevant signals for assigning the probability of obtaining a reward.”

    From Representation of Confidence Associated with a Decision by Neurons in the Parietal Cortex (2009) · cites this paper as [55]

  • LIP appears to play a role in transforming motion information into a saccadic choice.

    “Thus, LIP appears to play a role in transforming motion information into a saccadic choice, although that role might be shared among several oculomotor regions including the frontal eye field and superior colliculus that show similar responses during task performance27, 28.”

    From Neural correlates of perceptual learning in a sensory-motor, but not a sensory, cortical area (2008) · cites this paper as [26]

  • Decision computations represented in LIP appear to be critical for performance of trained monkeys.

    “These decision computations represented in LIP appear to be critical for performance of trained monkeys, an idea supported by a close relationship between LIP responses and reaction times25 and the ability to bias performance using electrical microstimulation of LIP26.”

    From Neural correlates of perceptual learning in a sensory-motor, but not a sensory, cortical area (2008) · cites this paper as [26]

  • When stimulus motion favors the target in the response field of an LIP neuron, firing rates build up progressively as monkeys form their decisions, and the rate of buildup is proportional to motion strength.

    “Specifically, when stimulus motion favors the target in the response field (RF) of an LIP neuron, firing rates build up progressively as monkeys form their decisions; the rate of buildup is proportional to motion strength.”

    From Decision-making with multiple alternatives (2008) · cites this paper as [8]

Cites

Flagged first, then by citations

Research works printed but not linked: 1

  1. Press, W.H., Flannery, B.P., Teukolsky, S.A. & Vetterling, W.T. Numerical Recipes in C 735 (Cambridge University Press, Cambridge, UK, 1988).

Cited by

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Related

Authors
Hanks, T. D., Ditterich, J., & Shadlen, M. N.
Affiliations
Howard Hughes Medical Institute (US)
Corresponding author
Shadlen, Michael N
ORCID
Venue
Nature Neuroscience
Publisher
Springer Science and Business Media LLC
Published
2006-04-09
Volume
9
Issue
5
Pages
682-689
ISSN
  • 1097-6256 (ISSN-L)
  • 1546-1726
DOI
10.1038/nn1683
PMC
PMC2770004
OpenAlex
W2117541477
Semantic Scholar
b34972b6dd40d2bbe836f4d2d960d702ec30a835
Cited by
360
References
51
Citations by year
2026: 13 · 2025: 13 · 2024: 14 · 2023: 11 · 2022: 14 · 2021: 19 · 2020: 16 · 2019: 19 · 2018: 14 · 2017: 26 · 2016: 17 · 2015: 19 · 2014: 21 · 2013: 18 · 2012: 19
FWCI
9.71
Type
journal article
Language
en
Open access
Licence
www.springer.com/tdm (tdm)
Locations
  • Nature Neuroscience (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • Howard Hughes Medical Institute
  • National Eye Institute (R01EY011378)
  • National Center for Research Resources (P51RR000166)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Visual perception and processing mechanisms
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Neural and Behavioral Psychology Studies
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Neural dynamics and brain function
Keywords
lateral intraparietal area, decision-making, motion discrimination, microstimulation, saccades, memory-guided saccades, reaction time, macaque
MeSH terms
Action Potentials, Animals, Behavior, Animal, Decision Making, Discrimination, Psychological, Electric Stimulation, Macaca mulatta, Motion Perception, Neurons, Parietal Lobe, Photic Stimulation, Reaction Time, Saccades

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

Statistics and arithmetic are recomputed, not judged.

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