Papers by Feng-Kuei Chiang
Zenodo (CERN European Organization for Nuclear Research), Nov 19, 2021
Summary<br> Neurons in primate lateral prefrontal cortex (LPFC) play a critical role in wor... more Summary<br> Neurons in primate lateral prefrontal cortex (LPFC) play a critical role in working memory (WM) and cognitive strategies. Consistent with adaptive coding models, responses of these neurons are not fixed, but flexibly adjust based on cognitive demands. However, little is known about how these adjustments affect population codes. Here, we investigated ensemble coding in LPFC while monkeys implemented different strategies in a WM task. Although single neurons were less tuned when monkeys used more stereotyped strategies, task information could still be accurately decoded from neural populations. This was due to changes in population codes that distributed information among a greater number of neurons, each contributing less to the overall population. Moreover, this shift occurred for task-relevant, but not irrelevant, information. These results demonstrate that cognitive strategies that impose structure on information held in mind rearrange population codes in LPFC, such that information becomes more distributed among neurons in an ensemble.<br>
Proceedings of the National Academy of Sciences of the United States of America, Apr 23, 2018
Pharmacology, Biochemistry and Behavior, Mar 1, 2015
Previous studies have shown that d-amphetamine, a dopamine (DA) indirect agonist, alters operant ... more Previous studies have shown that d-amphetamine, a dopamine (DA) indirect agonist, alters operant responding with respect to the behavior maintained on a differential reinforcement of low-rate (DRL) schedule of reinforcement. These behavioral changes have been presumed to result from drug-induced hyperdopaminergia that leads to activation of DA receptors. This study investigated the acute dose effects of DA receptor subtype-selective agonists on the performance of DRL 10-sec behavior by rats. SKF38393 (a D1 receptor agonist) and quinpirole (a D2/D3 receptor agonist) were able to dose-dependently disrupt DRL 10-sec behavior by decreasing the total responses, the non-reinforced responses, and the peak rate of response. Bromocriptine (a D2/D3 receptor agonist) produced a significantly different pattern of behavioral changes when examined during two distinct time phases (15 min and 3 hr after the drug injection). DRL responding was only altered at higher doses of bromocriptine in the second phase as indicated by decreasing reinforced responses and peak rate, together with an increase of burst responses. In contrast to the D1 and D2/D3 receptor agonists, PD168077 (a D4 receptor agonist) did not affect DRL 10-sec behavior. None of these tested drugs affected DRL 10-sec behavior in a manner similar to that of d-amphetamine. These findings show that there are differential effects on the performance of DRL 10-sec behavior when drugs are able to preferentially activate D1, D2/D3 and D4 receptors, supporting the assertion that there is functional heterogeneity of the DA receptor subtypes.
Neuron, Feb 1, 2022
Neurons in primate lateral prefrontal cortex (LPFC) play a critical role in working memory (WM) a... more Neurons in primate lateral prefrontal cortex (LPFC) play a critical role in working memory (WM) and cognitive strategies. Consistent with adaptive coding models, responses of these neurons are not fixed but flexibly adjust on the basis of cognitive demands. However, little is known about how these adjustments affect population codes. Here, we investigated ensemble coding in LPFC while monkeys implemented different strategies in a WM task. Although single neurons were less tuned when monkeys used more stereotyped strategies, task information could still be accurately decoded from neural populations. This was due to changes in population codes that distributed information among a greater number of neurons, each contributing less to the overall population. Moreover, this shift occurred for task-relevant, but not irrelevant, information. These results demonstrate that cognitive strategies that impose structure on information held in mind rearrange population codes in LPFC, such that information becomes more distributed among neurons in an ensemble.
Biological Psychiatry, May 1, 2022
Journal of Cognitive Neuroscience, Aug 1, 2018
■ Reinforcement learning models have proven highly effective for understanding learning in both a... more ■ Reinforcement learning models have proven highly effective for understanding learning in both artificial and biological systems. However, these models have difficulty in scaling up to the complexity of real-life environments. One solution is to incorporate the hierarchical structure of behavior. In hierarchical reinforcement learning, primitive actions are chunked together into more temporally abstract actions, called "options," that are reinforced by attaining a subgoal. These subgoals are capable of generating pseudoreward prediction errors, which are distinct from reward prediction errors that are associated with the final goal of the behavior. Studies in humans have shown that pseudoreward prediction errors positively correlate with activation of ACC. To determine how pseudoreward prediction errors are encoded at the single neuron level, we trained two animals to perform a primate version of the task used to generate these errors in humans. We recorded the electrical activity of neurons in ACC during performance of this task, as well as neurons in lateral prefrontal cortex and OFC. We found that the firing rate of a small population of neurons encoded pseudoreward prediction errors, and these neurons were restricted to ACC. Our results provide support for the idea that ACC may play an important role in encoding subgoals and pseudoreward prediction errors to support hierarchical reinforcement learning. One caveat is that neurons encoding pseudoreward prediction errors were relatively few in number, especially in comparison to neurons that encoded information about the main goal of the task. ■
本研究利用兩種時間關聯之操作式制約行為作業探討韁核的行為功能，一為區辨性增強低頻反應作業（簡稱DRL作業），另一為固定時距作業（簡稱FI作業）。本研究以神經毒素鵝膏蕈酸（ibotenic aci... more 本研究利用兩種時間關聯之操作式制約行為作業探討韁核的行為功能，一為區辨性增強低頻反應作業（簡稱DRL作業），另一為固定時距作業（簡稱FI作業）。本研究以神經毒素鵝膏蕈酸（ibotenic acid）破壞韁核的方式來測試大白鼠受試在上述行為作業之不同歷程的影響效果，包含習得歷程、行為表現階段以及已習得後轉換得酬賞之反應標準等三個階段。實驗一的結果顯示破壞韁核對於DRL作業的習得歷程具有明顯的影響，其影響效果在DRL短時距作業中造成無法以有效率的壓桿反應模式獲得酬賞；反之，破壞操弄的效果並不影響FI長與短時距作業的習得歷程。實驗二的結果顯示破壞韁核並不影響已習得的DRL作業與FI作業的行為表現，兩項作業的實驗組受試皆能維持穩定的行為反應模式且與控制組無明顯差異。實驗三對已習得的DRL行為進行時距參數的轉換（含調高及降低兩部份），結果顯示破壞韁核之操弄並未明顯的影響這項轉換新的時距之作業要求，但實驗組受試的確比控制組較遲緩達到新的時距要求。綜合而言，本研究以專屬性較高的神經毒素破壞韁核，用較多元指標的行為分析方式探討韁核的行為功能；其結果發現韁核參與DRL行為內含的區辨學習與對於錯誤偵測的負向迴饋，這些功能是需要透過韁核與其他中腦及邊緣系統的組織互動。This study examined the function of habenula (Hb) by two kinds of operant conditioned behavior tasks based on temporal contingency, including the differential reinforcement of low-rate responding (DRL) task and fixed-interval (FI) task. The effects of Hb lesion induced by neurotoxin ibotenic acid were examined at the different stages of operant conditioned behavior, including acquisition, performance, and transition stages. The results showed that bilateral lesi...
Neuron, 2022
Neurons in primate lateral prefrontal cortex (LPFC) play a critical role in working memory (WM) a... more Neurons in primate lateral prefrontal cortex (LPFC) play a critical role in working memory (WM) and cognitive strategies. Consistent with adaptive coding models, responses of these neurons are not fixed but flexibly adjust on the basis of cognitive demands. However, little is known about how these adjustments affect population codes. Here, we investigated ensemble coding in LPFC while monkeys implemented different strategies in a WM task. Although single neurons were less tuned when monkeys used more stereotyped strategies, task information could still be accurately decoded from neural populations. This was due to changes in population codes that distributed information among a greater number of neurons, each contributing less to the overall population. Moreover, this shift occurred for task-relevant, but not irrelevant, information. These results demonstrate that cognitive strategies that impose structure on information held in mind rearrange population codes in LPFC, such that inf...
Journal of Cognitive Neuroscience
Pharmacology, biochemistry, and behavior, Jan 10, 2015
Previous studies have shown that d-amphetamine, a dopamine (DA) indirect agonist, alters operant ... more Previous studies have shown that d-amphetamine, a dopamine (DA) indirect agonist, alters operant responding with respect to the behavior maintained on a differential reinforcement of low-rate (DRL) schedule of reinforcement. These behavioral changes have been presumed to result from drug-induced hyperdopaminergia that leads to activation of DA receptors. This study investigated the acute dose effects of DA receptor subtype-selective agonists on the performance of DRL 10-sec behavior by rats. SKF38393 (a D1 receptor agonist) and quinpirole (a D2/D3 receptor agonist) were able to dose-dependently disrupt DRL 10-sec behavior by decreasing the total responses, the non-reinforced responses, and the peak rate of response. Bromocriptine (a D2/D3 receptor agonist) produced a significantly different pattern of behavioral changes when examined during two distinct time phases (15min and 3hr after the drug injection). DRL responding was only altered at higher doses of bromocriptine in the secon...
Pharmacology Biochemistry and Behavior, Mar 1, 2015
Previous studies have shown that d-amphetamine, a dopamine (DA) indirect agonist, alters operant ... more Previous studies have shown that d-amphetamine, a dopamine (DA) indirect agonist, alters operant responding with respect to the behavior maintained on a differential reinforcement of low-rate (DRL) schedule of reinforcement. These behavioral changes have been presumed to result from drug-induced hyperdopaminergia that leads to activation of DA receptors. This study investigated the acute dose effects of DA receptor subtype-selective agonists on the performance of DRL 10-sec behavior by rats. SKF38393 (a D1 receptor agonist) and quinpirole (a D2/D3 receptor agonist) were able to dose-dependently disrupt DRL 10-sec behavior by decreasing the total responses, the non-reinforced responses, and the peak rate of response. Bromocriptine (a D2/D3 receptor agonist) produced a significantly different pattern of behavioral changes when examined during two distinct time phases (15min and 3hr after the drug injection). DRL responding was only altered at higher doses of bromocriptine in the second phase as indicated by decreasing reinforced responses and peak rate, together with an increase of burst responses. In contrast to the D1 and D2/D3 receptor agonists, PD168077 (a D4 receptor agonist) did not affect DRL 10-sec behavior. None of these tested drugs affected DRL 10-sec behavior in a manner similar to that of d-amphetamine. These findings show that there are differential effects on the performance of DRL 10-sec behavior when drugs are able to preferentially activate D1, D2/D3 and D4 receptors, supporting the assertion that there is functional heterogeneity of the DA receptor subtypes.
Proceedings of the National Academy of Sciences, Apr 23, 2018
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Papers by Feng-Kuei Chiang