Researcher: Gür, Ezgi
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Gür, Ezgi
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Publication Metadata only Sex differences in the timing behavior performance of 3xTg-AD and wild-type mice in the peak interval procedure(Elsevier, 2019) Fertan, Emre; Kosel, Filip; Wong, Aimee A.; Brown, Richard E.; N/A; Department of Psychology; Gür, Ezgi; Balcı, Fuat; PhD Student; Faculty Member; Department of Psychology; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; 51269We investigated interval timing behavior of 10-month-old male and female 3xTg-AD mice compared with their B6129F2/J wild type controls using the peak interval procedure with a 15 s target interval. Multiple parameters reflecting different aspects of timing performance were extracted from steady-state anticipatory nose-poking behavior using two different approaches: single trial analyses and average response curve analyses. These measures can dissociate the differences in performance due to distortions in the interval timing ability or to motivational decline (i.e. apathy); both of which have been reported in Alzheimer patients. We found that the interval timing ability of male and female 3xTg-AD mice did not differ from wild-type controls. However, in measures reflecting motivational state, we found significant sex differences regardless of genotype. Specifically, female mice initiated anticipatory responding later in the trial and had lower response amplitudes than males. Although our findings can also be interpreted in terms of differences in temporal control for response initiation, they more strongly suggest the effect of differential incentive motivation between sexes on timing behavior in these mice.Publication Metadata only Interval timing is disrupted in female 5xFAD mice: an indication of altered memory processes(Wiley, 2019) Fertan, Emre; Alkins, Kindree; Wong, Aimee A.; Brown, Richard E.; N/A; Department of Psychology; Gür, Ezgi; Balcı, Fuat; PhD Student; Faculty Member; Department of Psychology; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; 51269Temporal information processing in the seconds-to-minutes range is disrupted in patients with Alzheimer's disease (AD). In this study, we investigated the timing behavior of the 5xFAD mouse model of AD in the peak interval (PI) procedure. Nine-month-old female mice were trained with sucrose solution reinforcement for their first response after a fixed-interval (FI) and tested in the inter-mixed non-reinforced PI trials that lasted longer than FI. Timing performance indices were estimated from steady-state timed anticipatory nose-poking responses in the PI trials. We found that the time of maximal reward expectancy (peak time) of the 5xFAD mice was significantly earlier than that of the wild-type (WT) controls with no differences in other indices of timing performance. These behavioral differences corroborate the findings of previous studies on the disruption of temporal associative memory abilities of 5xFAD mice and can be accounted for by the scalar timing theory based on altered long-term memory consolidation of temporal information in the 5xFAD mice. This is the first study to directly show an interval timing phenotype in a genetic mouse model of AD.Publication Metadata only Mice optimize timed decisions about probabilistic outcomes under deadlines(Springer Heidelberg, 2017) N/A; Department of Psychology; Gür, Ezgi; Balcı, Fuat; PhD Student; Faculty Member; Department of Psychology; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; 51269Optimal performance in temporal decisions requires the integration of timing uncertainty with environmental statistics such as probability or cost functions. Reward maximization under response deadlines constitutes one of the most stringent examples of these problems. The current study investigated whether and how mice can optimize their timing behavior in a complex experimental setting under a response deadline in which reward maximization required the integration of timing uncertainty with a geometrically increasing probability/decreasing cost function. Mice optimized their performance under seconds-long response deadlines when the underlying function was reward probability but approached this level of performance when the underlying function was reward cost, only under the assumption of logarithmically scaled subjective costs. The same subjects were then tested in a timed response inhibition task characterized by response rules that conflicted with the initial task, not responding earlier than a schedule as opposed to not missing the deadline. Irrespective of original test groups, mice optimized the timing of their inhibitory control in the second experiment. These results provide strong support for the ubiquity of optimal temporal risk assessment in mice.Publication Metadata only Interval timing deficits and their neurobiological correlates in aging mice(Elsevier Science Inc, 2020) Arkan, Sertan; Karson, Ayşe; N/A; N/A; Department of Psychology; Gür, Ezgi; Duyan, Yalçın Akın; Balcı, Fuat; PhD Student; PhD Student; Faculty Member; Department of Psychology; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; N/A; 51269Age-related neurobiological and cognitive alterations suggest that interval timing (as a related function) is also altered in aging, which can, in turn, disrupt timing-dependent functions. We investigated alterations in interval timing with aging and accompanying neurobiological changes. We tested 4-6, 10-12, and 18-20 month-old mice on the dual peak interval procedure. Results revealed a specific deficit in the termination of timed responses (stop-times). The decision processes contributed more to timing variability (vs. clock/memory process) in the aged mice. We observed age-dependent reductions in the number of dopaminergic neurons in the VTA and SNc, cholinergic neurons in the medial septum/diagonal band (MS/DB) complex, and density of dopaminergic axon terminals in the DLS/DMS. Negative correlations were found between the number of dopaminergic neurons in the VTA and stop times, and the number of cholinergic neurons in MS/DB complex and the acquisition of stop times. Our results point at age-dependent changes in the decisional components of interval timing and the role of dopaminergic and cholinergic functions in these behavioral alterations. (C) 2020 Elsevier Inc. All rights reserved.Publication Metadata only Numerical averaging in mice(Springer Heidelberg, 2021) N/A; N/A; Department of Psychology; Gür, Ezgi; Duyan, Yalçın Akın; Balcı, Fuat; PhD Student; PhD Student; Faculty Member; Department of Psychology; Graduate School of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; N/A; 51269Rodents can be trained to associate different durations with different stimuli (e.g., light/sound). When the associated stimuli are presented together, maximal responding is observed around the average of individual durations (akin to averaging). The current study investigated whether mice can also average independently trained numerosities. Mice were initially trained to make 10 or 20 lever presses on a single (run) lever to obtain a reward and each fixed-ratio schedule was signaled either with an auditory or visual stimulus. Then, mice were trained to press another lever to obtain the reward after they responded on the run lever for the minimum number of presses [Fixed Consecutive Number (FCN)-10 or -20 trials] signaled by the corresponding discriminative stimulus. Following this training, FCN trials with the compound stimulus were introduced to test the counting behavior of mice when they encountered conflicting information regarding the number of responses required to obtain the reward. Our results showed that the numbers of responses on these compound test trials were around the average of the number of responses in FCN-10 and FCN-20 trials particularly when the auditory stimulus was associated with a fewer number of required responses. The counting strategy explained the behavior of the majority of the mice in the FCN-Compound test trials (as opposed to the timing strategy). The number of responses in FCN-Compound trials was accounted for equally well by the arithmetic, geometric, and Bayesian averages of the number of responses observed in FCN-10 and FCN-20 trials.Publication Metadata only Spontaneous integration of temporal information: implications for representational/computational capacity of animals(Springer Heidelberg, 2018) N/A; N/A; Department of Psychology; Gür, Ezgi; Duyan, Yalçın Akın; Balcı, Fuat; PhD Student; PhD Student; Faculty Member; Department of Psychology; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; N/A; 51269How do animals adapt their behaviors to changing conditions? This question relates to the debate between associative versus representational/computational approaches in cognitive science. an influential line of research that has significantly shaped the conceptual development of animal learning over decades has primarily focused on the role of associative dynamics with little-to-no ascription of representational/combinatorial capacities. the common assumption of these models is that behavioral adjustments are incremental and they result from updating of associations based on actions and their outcomes, without encoding the critical information serving as the determinant(s) of such contingencies (e.g., time in interval schedules, number in ratio schedules). on the other hand, An independent line of research provides evidence for behavioral phenomena that cannot be readily accounted for by the conventional associationist approach. in this paper, we will review different sets of findings particularly in the area of interval timing that suggest the ability of animals to make swift spontaneous computations on subjective quantities and incorporate them into their behavior. Findings of these studies constitute empirical challenges for the associationist approaches to behavioral flexibility. We argue that interval timing is a fertile ground for the formulation of critical tests of different theoretical approaches to animal behavior.Publication Metadata only Mice make temporal inferences about novel locations based on previously learned spatiotemporal contingencies(Springer Heidelberg, 2023) N/A; N/A; Department of Psychology; Gür, Ezgi; Duyan, Yalçın Akın; Balcı, Fuat; PhD Student; PhD Student; Faculty Member; Department of Psychology; Graduate School of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; N/A; 51269Animals learn multiple spatiotemporal contingencies and organize their anticipatory responses accordingly. The representational/computational capacity that underlies such spatiotemporally guided behaviors is not fully understood. To this end, we investigated whether mice make temporal inferences of novel locations based on previously learned spatiotemporal contingencies. We trained 18 C57BL/6J mice to anticipate reward after three different intervals at three different locations and tested their temporal expectations of a reward at five locations simultaneously, including two locations that were not previously associated with reward delivery but adjacent to the previously trained locations. If mice made spatiotemporal inferences, they were expected to interpolate between duration pairs associated with previously reinforced hoppers surrounding the novel hopper. We found that the maximal response rate at the novel locations indeed fell between the two intervals reinforced at the surrounding hoppers. We argue that this pattern of responding might be underlain by spatially constrained Bayesian computations.Publication Metadata only Mice are near optimal timers(Brill, 2022) Department of Psychology; N/A; N/A; Balcı, Fuat; Gür, Ezgi; Erdaǧı, Alihan; Faculty Member; PhD Student; PhD Student; Department of Psychology; College of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; Graduate School of Health Sciences; 51269; N/A; N/AMany conventional interval timing tasks do not contain asymmetric cost (loss) functions and thereby favor high temporal accuracy. On the other hand, asymmetric cost functions that differentially penalize/reinforce the early or late responses result in adaptive biases (shift) in timed responses due to timing uncertainty. Consequently, optimal performance in these tasks entails the normative parametrization of adaptive timing biases by the level of timing uncertainty. Differential reinforcement of response duration (DRRD) is one of these tasks that require mice to actively respond (e.g., continuously depressing a lever) for a minimum amount of time to be reinforced. The active production of a time interval by mice in DRRD differentiates this task from the differential reinforcement of low rates of responding (DRL) task as a passive waiting task that was used in earlier studies to investigate the optimality of adaptive biases in timing behavior. We tested 21 Th-Cre male mice (9 weeks old) in a DRRD task with a minimum requirement of 2 s. Mean response durations were positively biased (longer than the minimum requirement), and the extent of bias was predicted by the level of endogenous timing uncertainty. Mice nearly maximized the reward rate in this task. These results contribute to the accumulating evidence supporting optimal temporal risk assessment in non-human animals.Publication Metadata only A novel approach to extinction of acquired fear: intervening to reconsolidation process of fear memory(Türk Psikologlar Derneği, 2015) Dural, Seda; Çetinkaya, Hakan; Gür, Ezgi; PhD Student; Graduate School of Social Sciences and Humanities; N/ABehavioral techniques in the treatment of fear and anxiety-related disorders include the extinction of trauma-related responses. However, these techniques cannot prevent the recovery of fear and anxiety responses in the long run. Recently, studies of reconsolidation yielded results regarding persistent erasure of acquired fear responses when invasive (pharmacological) or non-invasive (behavioral) techniques interfered with the reconsolidation process. Despite several inconsistencies between the results of these studies, they appear to be very promising for the treatment of fear and anxiety-related disorders. The aim of this review is to discuss the reconsolidation studies (conducted since 2000) that have investigated the memory mechanisms regarding associative learning of fear and tested the reconsolidation hypothesis with either invasive or non-invasive techniques with human participants. If studies using these techniques reveal significant results in a consistent fashion and their reliability is well-established, they might make significant contributions to the field by facilitating the development of better clinical applications in terms of treating fear and anxiety-related disorders. / Öz: Kaygı ve korkunun tedavisinde kullanılan davranışsal teknikler, genel olarak, travmatik yaşantıya ilişkin tepkilerin söndürülmesini içermektedir. Öte yandan bu tekniklerin uzun vadede korku ve kaygı tepkilerinin yeniden ortaya çıkmasını engelleyemediği görülmektedir. Son zamanlarda yeniden-bütünleştirme hipotezi kapsamında yürütülen çalışmalar, korkuya ilişkin bellek materyaline yeniden-bütünleştirme sürecinde girişimsel (farmakolojik) ya da girişimsel olmayan (davranışsal) yöntemlerle müdahale edilmesinin, öğrenilmiş korku tepkilerinin kalıcı olarak ortadan kaldırılabileceğine –yani silinebileceğine– dair birtakım kanıtlar sağlamaktadır. Literatürde söz konusu bulguları desteklemeyen bazı çalışmalar olmakla birlikte, genel olarak değerlendirildiğinde, söz konusu yaklaşımın kaygı ve korku ilişkili bozuklukların tedavisinde umut vaat ettiği görülmektedir. Sunulan derleme çalışması ile 2000’li yıllardan itibaren korkunun bağıntısal olarak öğrenilmesine ilişkin bellek mekanizmaları kapsamında, yeniden-bütünleştirme hipotezini girişimsel ve girişimsel olmayan teknikler aracılığıyla, insan katılımcılarda test eden çalışmaları bir araya getirmek amaçlamıştır. Bu tekniklerin başarılı olması ve güvenilirliklerinin kanıtlanması durumunda, korku temelli psikolojik bozuklukların tedavi edilmesine yönelik yeni klinik uygulamaların geliştirilmesinin alana önemli katkılar sağlayabileceği düşünülmektedir.Publication Metadata only Count-based decision-making in mice: numerosity vs. stimulus control(2022) N/A; N/A; Department of Psychology; Toptaş, Pınar; Gür, Ezgi; Balcı, Fuat; Master Student; PhD Student; Faculty Member; Department of Psychology; Graduate School of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; N/A; 51269Numerical and temporal control of behavior is ubiquitous across many species of animals. Recent studies showed that in the presence of reliable discriminative stimuli, mice ignore temporal relations and probabilistic information but when discriminative stimuli become non-informative, the same mice can spontaneously start relying on previously experienced time intervals and probabilities. Similar dynamics do not readily generalize to counting behavior since the response-outcome contingency functions differ when reinforcement depends on the number vs. timing of responding. In the current study, mice (N = 32) learned to press two different levers 10 (few) or 20 (many) times, while the active lever was signaled by a light stimulus. The probability of the few/many trials was manipulated between groups. During testing, the informative value of light stimulus was eliminated by signaling both few- and many-levers. In a quarter of training trials, mice ignored the discriminative stimulus and adopted a numerical decision strategy (starting to respond on the few-option and then switching to the many-option in many trials) that was sensitive to probabilistic information. The frequency but not the probability-sensitive parametrization of switching behavior changed when the discriminative stimulus became non-informative in testing. These findings suggest that there is a relatively strong representational control over counting behavior even in conditions that afford strong stimulus control.