Abstracts of Conference Presentations – Posters and Talks
February 28th, 2011 6:23pm
Cognitive Neuroscience Society 2011 (San Francisco, CA)
Cognitive depletion has a negative impact on the rate of implicit perceptual-motor sequence learning
Abigail H. Wesley, Daniel J. Sanchez, Paul J. Reber
Ego-depletion theory states that humans possess a limited store of cognitive resources that, when depleted, produce deficits in self-regulation or cognitive control. Depletion effects on implicit learning, which is not thought to require cognitive control, have not previously been reported. However, if depletion reflects transiently lower levels of dopamine, ego-depletion might be associated with slower learning for tasks dependent on dopamine-gated plasticity in cortico-striatal circuits. The relationship between ego-depletion and implicit learning was examined by comparing participants’ levels of cognitive depletion with sequence learning performance. Participants first completed the Stroop Task to assess depletion, measured as the reaction time difference between control and incongruent trials. Participants then performed the Serial Interception Sequence Learning (SISL) task. The SISL task is a perceptual-motor sequence learning task whereby circular cues scroll across a computer screen toward targets, and participants attempt to press the correct key when a cue fits within the target zone. Participants received 2880 trials of training on a covertly embedded 12-item second-order conditional sequence, followed by tests of both implicit and explicit sequence knowledge. Implicit sequence knowledge was assessed as the percent correct difference between performance on the trained sequence and novel sequences. A negative correlation was found between the interference effect and the amount of implicit learning exhibited, with a slightly stronger relationship observed for participants who did not demonstrate explicit knowledge of the sequence. These results show that ego depletion may lead to slower implicit learning, implying this process is not as automatic as previously hypothesized.
Posted by Abbie
November 30th, 2010 10:56am
Psychonomic Society 2010 (St. Louis, MO)
Combining Physical Exercise and Repetition-Lag Training to Improve Everyday Memory Function in Older Adults
Gigler, K. L., Jennings, J. J., Dagenbach, D., Katula, J. A., Dove, R. W., & Stark, S.
Cognitive and physical activity interventions have been shown to improve older adults’ performance on lab-based measures of memory and executive function. However, less work has examined the real-world benefits of these two types of interventions, particularly when administered in conjunction with one another. The present study, which was part of the Seniors Health and Activity Research Program pilot trial, explored the independent and combined effects of repetition-lag memory training and aerobic exer- cise training on the frequency of self-reported memory errors in older adults. Following 4 months of training, a significant decrease in errors was observed for both the repetition-lag-only group and the combined exercise and repetition-lag group, with no benefit for the exercise-only participants. These results suggest that repetition-lag training may be more efficacious than physical exercise for reducing everyday memory errors and that cognitive and physical activity training may not produce
additive effects when administered together.
Posted by Kati
November 29th, 2010 2:21pm
Cognitive Neuroscience Society 2011 (San Francisco, CA)
Enhancing motor memory for a melodic sequence by re-playing the melody during sleep
James W. Antony, Eric W. Gobel, Justin K. O’Hare, Paul J. Reber & Ken A. Paller
Northwestern University
A steadily increasing body of evidence supports a role for sleep in memory reactivation and consolidation. Memory traces are thought to be spontaneously reactivated during sleep, enhancing storage and improving subsequent memory performance. This natural process can apparently be triggered by auditory or olfactory stimuli during sleep, if those stimuli had previously been linked with learning (Rasch et al., 2007; Rudoy et al., 2009; Smith & Weeden, 1990). We now report that motor memories for a 12-item musical sequence, played using four fingers on four keys in time with moving visual cues (as in the video game, “Guitar Hero”), can be improved by presenting the corresponding tone sequences during sleep. Sixteen participants learned two repeating melodies composed with either four high tones or four low tones. Training involved 40 repetitions of each sequence in interleaved blocks. Performance was tested before and after a 90-minute afternoon nap. Responses were scored as correct only if made with the correct key and within the target time window. Performance on the learned sequences was superior to performance on novel sequences. Crucially, one musical sequence was played softly through a speaker 20 times during a 4-minute segment of slow-wave sleep, without the participants’ knowledge. After the nap, but not before, performance was significantly better on the cued sequence than on the non-cued sequence. These results demonstrate that motor memories can be selectively enhanced during sleep, most likely because reinstating the tone sequence reactivated corresponding representations of the visual cues and/or the learned motor sequence.
Posted by Paul
November 23rd, 2010 4:18pm
Reber, Sanchez, & Fraser – CNS 2011
Consolidation in implicit sequence learning: Retroactive interference effects modulated by concomitant explicit knowledge
Paul J. Reber1, Daniel J. Sanchez1, David Fraser2;1Northwestern University, 2Chatham University
Memory consolidation is a vital process by which knowledge representations become stable and long-lasting. While well-studied in declarative memory, implicit skill learning also appears to undergo a consolidation process after the training period. Immediately after learning a new motor sequence, knowledge may be vulnerable to retroactive interference from learning of another novel sequence. To assess whether retroactive interference is observed during implicit perceptual-motor sequence learning, participants learned three different 12-item second-order conditional sequences over two sessions using the Serial Interception Sequence Learning (SISL) task. In the SISL task, cues scroll vertically towards targets on a computer screen. Participants attempt to press a corresponding key when a cue reaches its target zone. During the first session participants trained on a first sequence (A), which was immediately followed by training on a second sequence (B). Either 24 or 48 hours later, participants returned for a second session and trained on a third sequence (C), followed by tests for implicit and explicit sequence knowledge for all three sequences. Retroactive interference for sequence A was observed in participants who had low explicit knowledge of sequence A, but not in participants with high explicit knowledge. No interference was observed for sequence B, for which there was a substantial delay period prior to learning sequence C. These results suggest that implicit sequence learning requires a consolidation period to avoid retroactive interference, but this interference effect can be ameliorated by concomitant explicit sequence knowledge.
Posted by Paul
November 23rd, 2010 2:14pm
Wesley, Sanchez, & Reber – CNS 2011
Cognitive depletion has a negative impact on the rate of implicit perceptual-motor sequence learning
Abigail H. Wesley, Daniel J. Sanchez, Paul J. Reber
Ego-depletion theory states that humans possess a limited store of cognitive resources that, when depleted, produce deficits in self-regulation or cognitive control. Depletion effects on implicit learning, which is not thought to require cognitive control, have not previously been reported. However, if depletion reflects transiently lower levels of dopamine, ego-depletion might be associated with slower learning for tasks dependent on dopamine-gated plasticity in cortico-striatal circuits. The relationship between ego-depletion and implicit learning was examined by comparing participants’ levels of cognitive depletion with sequence learning performance. Participants first completed the Stroop Task to assess depletion, measured as the reaction time difference between control and incongruent trials. Participants then performed the Serial Interception Sequence Learning (SISL) task. The SISL task is a perceptual-motor sequence learning task whereby circular cues scroll across a computer screen toward targets, and participants attempt to press the correct key when a cue fits within the target zone. Participants received 2880 trials of training on a covertly embedded 12-item second-order conditional sequence, followed by tests of both implicit and explicit sequence knowledge. Implicit sequence knowledge was assessed as the percent correct difference between performance on the trained sequence and novel sequences. A negative correlation was found between the interference effect and the amount of implicit learning exhibited, with a slightly stronger relationship observed for participants who did not demonstrate explicit knowledge of the sequence. These results show that ego depletion may lead to slower implicit learning, implying this process is not as automatic as previously hypothesized.
Posted by Abbie
November 23rd, 2010 1:29pm
Implicit learning of a serial interception sequence by cognitively healthy elderly participants
Eric W. Gobel1,2, Kelsey M. Blomeke2, Sandra Weintraub3,4, and Paul J. Reber2
1Interdepartmental Neuroscience Program, 2Department of Psychology, 3Cognitive Neurology and Alzheimer’s Disease Center, and 4Departments of Psychiatry and Neurology
Northwestern University, Evanston, IL, and Northwestern Feinberg School Of Medicine, Chicago, IL
Cognitive Neuroscience Society Annual Meeting 2011
Skilled performance of complex motor skills requires learning a specific order of movements with precise timing. The Serial Interception Sequence Learning (SISL) task has been used to study this type of perceptual-motor sequence learning. During SISL, participants make keypress responses to coincide with the passage of a moving spatial cue though a target zone. Participants are not told that the cues follow a repeating sequence, but implicit sequence knowledge is observed through sequence-specific performance enhancement. Implicit learning with little concomitant explicit knowledge of the sequence has been demonstrated in undergraduate populations. This implicit-explicit memory dissociation is likely enhanced by the continuous performance demands and video-game-like interface. However, it is not known if SISL will be an effective tool for examining sequence learning in older adults given the overall task difficulty. Cognitively healthy elderly participants (mean age 70.0 years, range 63 – 76) performed a modified SISL task designed to provide an appropriate level of difficulty. The number of possible responses was reduced to three (making the task unimanual) and an initial performance pre-assessment identified an appropriate cue velocity for each participant. As in prior research, cues followed a 12-item repeating sequence during 80% of training trials. On a subsequent test phase, participants exhibited implicit sequence knowledge but no ability to recognize or recall the trained sequence. This cognitively healthy elderly sample demonstrated reliable implicit learning and would serve as a suitable comparison group for patient populations with impaired memory function, such as those with MCI, Alzheimer’s disease, and Parkinson’s disease.
Posted by egobel
November 23rd, 2010 11:31am
Sanchez, Wesley, & Reber – CNS, 2011
Who reads the instructions, anyway? Explicit knowledge benefits perceptual-motor sequence learning independent of instruction.
Sanchez, D.J., Wesley, A.H., & Reber, P.J.
Motor skill training, outside of the laboratory, is typically accompanied by explicit instruction for the sequence of motor movements to be learned. However, expert performance is often unaccompanied by awareness of the sequence being executed, suggesting a role for implicit learning. Perceptual-motor sequence learning was assessed with, and without, explicit pre-instruction in order to examine the effect of explicit instruction on skill learning. Participants in the explicit instruction condition observed the 12-item training sequence five times before training, whereas in the implicit condition no mention was made of the repeating sequence. Both groups received 2880 trials of training with the Serial Interception Sequence Learning (SISL) task, followed by tests of implicit and explicit sequence knowledge. In the SISL task, cues scroll vertically towards targets on a computer screen and participants attempt to press a corresponding key when a cue reaches its target zone. Explicit instruction did not reliably affect sequence learning overall, but did lead to high levels of explicit knowledge in many, but not all, of these participants. Some participants in the implicit training condition acquired significant explicit knowledge as well. Participants were divided post-hoc into high and low explicit knowledge groups by the median of the sequence recognition test scores. Participants with greater explicit knowledge exhibited better learning of the embedded repeating sequence than those with only implicit knowledge, after an initial period of similar performance. This suggests that even with a continuous performance task requiring precisely timed responses, explicit knowledge provides a benefit to procedural learning. (249)
Posted by Danny
March 18th, 2010 4:03pm
Neural correlates of the integration of timing with order in perceptual-motor sequence learning
Eric W. Gobel, Paul J. Reber; Northwestern University
Society for Neuroscience Annual Meeting 2009, Chicago, IL. 21 Oct 2009.
Most well practiced perceptual-motor skills that we execute are composed of a learned sequence of movements that must be performed in a particular order with specific timing. Experiments described here support the idea that order and timing are interdependent and integrated in perceptual-motor sequence learning. Furthermore, there are distinct regions of the brain that process the separate order and timing components and their integration.
To study the neural underpinnings of order and timing in implicit perceptual-motor sequence learning, a new paradigm was developed emphasizing precise timing in the response to a moving visual cue and allowing for timing information to be embedded in the response sequence. In this paradigm, circular cues move upwards on the screen toward four target regions. Participants are instructed to press a corresponding key when a cue is centered within the target region. In a behavioral experiment, participants learned a repeating 12-item sequence of responses with embedded timing information: responses were separated by either 350ms or 700ms in a repeating pattern. Overall performance on the task improved over time, as measured by decreasing error rates. When a novel pseudo-random series of responses was required instead of the repeating sequence, the error rate increased significantly, showing that participants had acquired implicit knowledge of the specific practiced sequence.
After learning, participants performed four transfer conditions, which maintained either the ordinal sequence, the timing sequence, both sequences, or neither sequence. Participants exhibited high levels of performance only when the test sequence was identical to the training conditions, maintaining both the order and inter-item timing. When either the order of actions or the timing intervals between actions was changed, participants’ performance dropped to a level equivalent to that of a completely novel sequence. These results demonstrate that timing information is tightly integrated with order information in a learned perceptual-motor sequence.
Functional imaging of the transfer conditions was performed to identify the brain circuits mediating performance of the order and timing integration components of the practiced sequence. Results suggest that cerebellar and anterior precuneus activity is correlated with executing an integrated order and timing sequence, while posterior precuneus and anterior cingulate activity is correlated with executing a practiced order of movements, independent of timing.
Posted by egobel
March 12th, 2010 6:18pm
Operating characteristics of the implicit procedural learning system
Sanchez, D.J., Gobel, E.W., Reber, P.J. CNADC 16th Annual Alzheimer Day. May 6th, 2010.
The majority of actions we take to accomplish everyday activities are based around routine behaviors. The procedural learning involved in developing a routine behavior, or skill, relies on an implicit memory system preserved in patients with Alzheimer’s disease. Rooted in the basal ganglia and connected cortico-striatal circuits, this preserved learning may support cognitive rehabilitation that utilizes abilities that AD patients retain. It is therefore critical to understand the capacity and operating characteristics of this type of memory. Procedural learning can be isolated from other types of memory in a perceptual-motor sequence learning task, such as the serial interception sequence learning (SISL) task. Based on the well-studied serial reaction time (SRT) task, the SISL task requires participants to make continuous sequences of keypress responses to cues scrolling vertically up a computer screen. Participants are instructed to time their response to coincide with a cue reaching a stationary target on the opposite end of the screen. Participants are not told that the cues appear in a repeating sequence (typically 12 items long), but they do show gradual improvements in performance that reflect learning of the repeating sequence.
Three experiments are reported that use the SISL task to examine procedural learning dependent on cortico-striatal circuits. In the first experiment, participants learned to perform the SISL task more accurately after practice with a repeating sequence but exhibited little or no explicit, conscious memory of the repeating sequence. This result shows that learning in this task is independent of the explicit memory system that is impaired in Alzheimer’s disease. In a second experiment, participants learned a repeating sequence with an embedded timing structure. When presented with the same sequence of motor responses but novel inter-item timing, performance was as poor as with a novel sequence. The lack of transfer indicates that this type of procedural learning integrates both action selection and timing. In a third experiment, participants exhibited significant learning of much longer sequences than have previously been studied; up to 80 items long. The ability to learn such long sequences indicates that the cortico-striatal learning system has a greater learning capacity than has previously been appreciated. By furthering our understanding of the function and capacities of this learning system, future work may be able to develop a cognitive rehabilitation approach that builds on this preserved memory function and improves general cognitive function in memory-disordered patients.
Posted by Danny
March 5th, 2010 2:48pm
Stretching the implicit muscle: A parametric study of perceptual-motor sequence learning using extended sequence lengths.
Sanchez, D.J. & Reber, P.J. Cognitive Neuroscience Society Meeting 2010.
Perceptual-motor sequence learning has an extensive research history, but most studies have relied on using short sequences of five to twelve items. Utilizing a new Serial Interception Sequence Learning (SISL) task, the implicit learning of longer motor sequences was examined to explore the learning rate and limit of information complexity that can be learned in short training sessions. In the SISL task, cues scroll vertically towards targets on a computer screen. Participants attempt to press a corresponding key when a cue reaches its target zone. Participants were not told that the cues followed a repeating sequence. Twenty percent of the training trials were in a random order to obscure the repetitions. To maintain task difficulty over practice, the velocity of the cues increased as task performance improved. Implicit knowledge was assessed by comparing performance on the SISL task for the trained sequence against novel sequences. Training began with 30-item sequences and subsequent groups received successively longer sequence lengths. After the implicit test, participants were informed about the repeating sequence and performed recognition and verbal recall tests. For recognition, participants rated five sequences as to how likely it was that each sequence was the one that had been practiced. Even with extended-length sequences, participants exhibited sequence-specific learning within an hour of training. The steep decline in recognition performance for sequences exceeding 30 items suggests that implicit memory systems are primarily driving the perceptual-motor sequence learning. These results provide broader insight into the capabilities of the brain regions responsible for implicit learning.
Posted by admin