Early Phase Of Learning Research Articles

Encoding attentional states during visuomotor adaptation.

We recently showed that visuomotor adaptation acquired under attentional distraction is better recalled under a similar level of distraction compared to no distraction. This paradoxical effect suggests that attentional state (e.g., divided or undivided) is encoded as an internal context during visuomotor learning and should be reinstated for successful recall (Song & Bédard, 2015). To investigate if there is a critical temporal window for encoding attentional state in visuomotor memory, we manipulated whether participants performed the secondary attention-demanding task concurrently in the early or late phase of visuomotor learning. Recall performance was enhanced when the attentional states between recall and the early phase of visuomotor learning were consistent. However, it reverted to untrained levels when tested under the attentional state of the late-phase learning. This suggests that attentional state is primarily encoded during the early phase of learning before motor errors decrease and reach an asymptote. Furthermore, we demonstrate that when divided and undivided attentional states were mixed during visuomotor adaptation, only divided attention was encoded as an internal cue for memory retrieval. Therefore, a single attentional state appears to be primarily integrated with visuomotor memory while motor error reduction is in progress during learning.

Early motor learning changes in upper-limb dynamics and shoulder complex loading during handrim wheelchair propulsion.

BackgroundTo propel in an energy-efficient manner, handrim wheelchair users must learn to control the bimanually applied forces onto the rims, preserving both speed and direction of locomotion. Previous studies have found an increase in mechanical efficiency due to motor learning associated with changes in propulsion technique, but it is unclear in what way the propulsion technique impacts the load on the shoulder complex. The purpose of this study was to evaluate mechanical efficiency, propulsion technique and load on the shoulder complex during the initial stage of motor learning.Methods15 naive able-bodied participants received 12-minutes uninstructed wheelchair practice on a motor driven treadmill, consisting of three 4-minute blocks separated by two minutes rest. Practice was performed at a fixed belt speed (v = 1.1 m/s) and constant low-intensity power output (0.2 W/kg). Energy consumption, kinematics and kinetics of propulsion technique were continuously measured. The Delft Shoulder Model was used to calculate net joint moments, muscle activity and glenohumeral reaction force.ResultsWith practice mechanical efficiency increased and propulsion technique changed, reflected by a reduced push frequency and increased work per push, performed over a larger contact angle, with more tangentially applied force and reduced power losses before and after each push. Contrary to our expectations, the above mentioned propulsion technique changes were found together with an increased load on the shoulder complex reflected by higher net moments, a higher total muscle power and higher peak and mean glenohumeral reaction forces.ConclusionsIt appears that the early stages of motor learning in handrim wheelchair propulsion are indeed associated with improved technique and efficiency due to optimization of the kinematics and dynamics of the upper extremity. This process goes at the cost of an increased muscular effort and mechanical loading of the shoulder complex. This seems to be associated with an unchanged stable function of the trunk and could be due to the early learning phase where participants still have to learn to effectively use the full movement amplitude available within the wheelchair-user combination. Apparently whole body energy efficiency has priority over mechanical loading in the early stages of learning to propel a handrim wheelchair.

Board #130 - Research Abstract Performance and Cognitive Load Among Novices Training on Simple vs. Complex Simulation Scenarios During Procedural Skills Training

Hypothesis A common belief in healthcare simulation is that higher realism results in improved learning.1-2 Predicated on the concept of context dependency (CD),3 proponents of this view advocate for simulations that recreate the contextual realities of clinical practice,4 arguing such environments help learners develop, coordinate and transfer constituent skills from simulation to clinical care.5 However, the evidence supporting this belief is mixed.6 A potential explanation for these disparate findings is that although higher realism may improve transfer through the CD effect, for novices it may also lead to increased task complexity. In turn, higher complexity may increases novices’ cognitive load (CL) to a point that is detrimental for learning, resulting in reduced transfer.7 The purpose of this study was to test these competing hypotheses by examining the effect of scenario complexity and CD on performance and CL during procedural skill acquisition, retention and transfer. Methods Novice medical students (n = 38) were randomly assigned to training on a simple or complex Lumbar Puncture (LP) simulation (Fig 1A and 1B), consisting of four practice trials interspersed with controlled feedback (acquisition phase). After 10 days, novices completed one trial on their training scenario (retention phase). Finally, to test the competing effects of CD vs. high task complexity, novices completed one trial on a very complex hybrid simulation (Fig 1C)8 contextually similar to the complex scenario (transfer phase). On all trials, LP performance was assessed using a global rating scale (GRS)9 and number of sterility breaches, while CL was measured using subjective ratings of mental effort (SRME) and reaction time (RT) to a vibrotactile secondary task.10-11 Acquisition and retention scores were analyzed using mixed 2x4 and 2x2 ANOVA; transfer scores were analyzed using t-tests. Effect sizes are reported as Cohen’s f or d, p<0.05 was considered statistically significant. Results Both groups demonstrated improved LP performance and fewer sterility breaches from the beginning to the end of the acquisition phase (p = 0.001, f = 0.96 for GRS; p = 0.001, f = 0.50 for sterility) and maintained this at retention. Novices in the simple group demonstrated superior LP performance and fewer sterility breaches compared to those in the complex group during acquisition (p = 0.002, d = 1.13 for GRS; p = 0.001, d = 1.60 for sterility) and at retention (p = 0.001, d = 1.25 for GRS; p = 0.001, d = 1.72 for sterility). CL decreased faster for novices in the simple group during acquisition (p = 0.005, f = 0.36 for SRME and p = 0.011, f = 0.35 for RT) and the simple group maintained lower CL at retention (p = 0.001, d = 1.39 for SRME and p = 0.021, d = 0.81 for RT). On transfer to the very complex simulation scenario, no differences in CL or GRS scores were observed between the two groups, however the simple group continued to make fewer sterility breaches (p = 0.023, d = 0.80). Conclusion This study provides empirical data explaining why higher realism may result in equivocal transfer among novice learners. Lower task complexity was associated with improved procedural performance during skill acquisition and faster decline in CL, which was retained after a 1-week delay. However, with the exception of fewer sterility breaches, the benefits of training on a simpler scenario were eliminated upon transfer to a very complex hybrid simulation. The equivalent performance of both groups raises the possibility that both CD and CL can impact transfer of procedural skills during simulation-based training. These competing effects should be balanced by simulation instructional designers, for instance by using a progressive sequence of training that reduces cognitive load in the early phases of learning and exposes the learner to more complex scenarios later in training.[5]

The early phase of /see symbol/ production development in adult Japanese learners of English.

Although previous research indicates that Japanese speakers' second language (L2) perception and production of English /see symbol/ may improve with increased L2 experience, relatively little is known about the fine phonetic details of their /see symbol/ productions, especially during the early phase of L2 speech learning. This cross-sectional study examined acoustic properties of word-initial /see symbol/ from 60 Japanese learners with a length of residence of between one month and one year in Canada. Their performance was compared to that of 15 native speakers of English and 15 low-proficiency Japanese learners of English. Formant frequencies (F2 and F3) and F1 transition durations were evaluated under three task conditions--word reading, sentence reading, and timed picture description. Learners with as little as two to three months of residence demonstrated target-like F2 frequencies. In addition, increased LOR was predictive of more target-like transition durations. Although the learners showed some improvement in F3 as a function of LOR, they did so mainly at a controlled level of speech production. The findings suggest that during the early phase of L2 segmental development, production accuracy is task-dependent and is influenced by the availability of L1 phonetic cues for redeployment in L2.

A Role for Chunk Formation in Statistical Learning of Second Language Syntax

Humans are remarkably sensitive to the statistical structure of language. However, different mechanisms have been proposed to account for such statistical sensitivities. The present study compared adult learning of syntax and the ability of two models of statistical learning to simulate human performance: Simple Recurrent Networks, which learn by predictive computation, and PARSER, which learns chunks as a byproduct of general principles of associative learning and memory. In the first stage, a semiartificial language paradigm was used to gather human data. In the second stage, a simulation paradigm was then used to compare the patterns of performance of the SRN and PARSER. After the human adults and the computational models were trained on sentences from the semiartificial language with probabilistic syntax, their learning outcomes were compared. Neither model was able to fully reproduce the human data, which may indicate less robust statistical learning effects in adults; however, PARSER was able to simulate more of the adult learning data than the SRN, suggesting a possible role for chunk formation in early phases of adult learning of second language syntax.

The subthalamic nucleus modulates the early phase of probabilistic classification learning

Previous models proposed that the subthalamic nucleus (STN) is critical in the early phase of skill acquisition. We hypothesized that subthalamic deep brain stimulation modulates the learning curve in early classification learning. Thirteen idiopathic Parkinson's disease patients (iPD) with subthalamic deep brain stimulation (STN-DBS), 9 medically treated iPD, and 21 age-matched healthy controls were tested with a probabilistic classification task. STN-DBS patients were tested with stimulation OFF and ON, and medically treated patients with medication OFF and ON, respectively. Performance and reaction time were analyzed on the first 100 consecutive trials as early learning phase. Moreover, data were separated for low and high-probability patterns, and more differentiated strategy analyses were used. The major finding was a significant modulation of the learning curve in DBS patients with stimulation ON: although overall learning was similar to healthy controls, only the stimulation ON group showed a transient significant performance dip from trials '41-60' that rapidly recovered. Further analysis indicated that this might be paralleled by a modulation of the learning strategy, particularly on the high-probability patterns. The reaction time was unchanged during the dip. Our study supports that the STN serves as a relay in early classification learning and directs attention toward unacquainted content. The STN might play a role in balancing the short-term success against strategy optimization for improved long-term outcome.

Distinct and simultaneously active plasticity mechanisms in mouse hippocampus during different phases of Morris water maze training

Although the Morris water maze (MWM) is the most frequently used protocol to examine hippocampus-dependent learning in mice, not much is known about the spatio-temporal dynamics of underlying plasticity processes. Here, we studied molecular and cellular hippocampal plasticity mechanisms during early and late phases of spatial learning in the MWM. Quantitative in situ hybridization for the immediate early genes zif268 and Homer1a (H1a) revealed phase-dependent differences in their expression between areas CA1 and CA3. During the initial learning phase, CA1 expression levels of the molecular plasticity marker H1a, but not of the activity reporter gene zif268, were related to task proficiency; whereas no learning-specific changes could be detected in CA3. Simultaneously, the ratio of surface-expressed NMDAR subunits NR2A and NR2B was downregulated as measured by acute slice biotinylation assay, while the total number of surface NMDARs was unaltered. When intrinsic 'somatic' and synaptic plasticity in the CA1-region of hippocampal slices were examined, we found that early learning promotes intrinsic neuronal plasticity as manifested by a reduction of spike frequency adaptation and postburst afterhyperpolarization. At the synaptic level, however, maintenance of long-term potentiation (LTP) in all learning groups was impaired which is most likely due to 'intrinsic' learning-induced LTP which occluded any further electrically induced LTP. Late learning, in contrast, was characterized by re-normalized H1a, NR2A and NR2B expression and neuronal firing, yet a further strengthening of learning-induced LTP. Together, our data support a precisely timed cascade of complex molecular and subcellular transformations occurring from early to late MWM learning.

Expression of microRNAs and Other Small RNAs in Prefrontal Cortex in Schizophrenia, Bipolar Disorder and Depressed Subjects

Because of the role played by miRNAs in post-transcriptional regulation of an array of genes, their impact in neuropsychiatric disease pathophysiology has increasingly been evident. In the present study, we assessed microRNA expression in prefrontal cortex (Brodmann area 10) of a well-characterized cohort of major depressed, bipolar, and schizophrenia subjects (obtained from Stanley Neuropathology Consortium; n = 15 in each group), using high throughput RT-PCR plates. Discrete miRNA alterations were observed in all disorders, as well as in suicide subjects (pooled across diagnostic categories) compared to all non-suicide subjects. The changes in the schizophrenia group were partially similar to those in the bipolar group, but distinct from changes in depression and suicide. Intriguingly, those miRNAs which were down-regulated in the schizophrenia group tended to be synaptically enriched, whereas up-regulated miRNAs tended not to be. To follow this up, we purified synaptosomes from pooled samples of the schizophrenia vs. control groups and subjected them to Illumina deep sequencing. There was a significant loss of small RNA expression in schizophrenia synaptosomes only for certain sequence lengths within the miRNA range. Moreover, 73 miRNAs were significantly down-regulated whereas only one was up-regulated. Strikingly, across all expressed miRNAs in synaptosomes, there was a significant inverse correlation between the fold-change of a given miRNA seen in schizophrenia and its synaptic enrichment ratio observed in controls. Thus, synaptic miRNAs tended to be down-regulated in schizophrenia, and the more highly synaptically enriched miRNAs tended to show greater down-regulation. These findings point to some deficit in miRNA biogenesis, transport, processing or turnover in schizophrenia that is selective for the synaptic compartment. A novel class of ncRNA-derived small RNAs, shown to be strongly induced during an early phase of learning in mouse, is also expressed in man, and at least one representative (SNORD85) was strongly down-regulated in schizophrenia synaptosomes.

Role of the Plasticity-Associated Transcription Factor Zif268 in the Early Phase of Instrumental Learning

Gene transcription is essential for learning, but the precise role of transcription factors that control expression of many other genes in specific learning paradigms is yet poorly understood. Zif268 (Krox24/Egr-1) is a transcription factor and an immediate-early gene associated with memory consolidation and reconsolidation, and induced in the striatum after addictive drugs exposure. In contrast, very little is known about its physiological role at early stages of operant learning. We investigated the role of Zif268 in operant conditioning for food. Zif268 expression was increased in all regions of the dorsal striatum and nucleus accumbens in mice subjected to the first session of operant conditioning. In contrast, Zif268 increase in the dorsomedial caudate-putamen and nucleus accumbens core was not detected in yoked mice passively receiving the food reward. This indicates that Zif268 induction in these structures is linked to experiencing or learning contingency, but not to reward delivery. When the task was learned (5 sessions), Zif268 induction disappeared in the nucleus accumbens and decreased in the medial caudate-putamen, whereas it remained high in the lateral caudate-putamen, previously implicated in habit formation. In transgenic mice expressing green fluorescent protein (GFP) in the striatonigral neurons, Zif268 induction occured after the first training session in both GFP-positive and negative neurons indicating an enhanced Zif268 expression in both striatonigral and striatopallidal neurons. Mutant mice lacking Zif268 expression obtained less rewards, but displayed a normal discrimination between reinforced and non-reinforced targets, and an unaltered approach to food delivery box. In addition, their motivation to obtain food rewards, evaluated in a progressive ratio schedule, was blunted. In conclusion, Zif268 participates in the processes underlying performance and motivation to execute food-conditioned instrumental task.

The Effectiveness of a 2‐year Supplementary Tutor‐assisted Computerized Intervention on the Reading Development of Beginning Readers at Risk for Reading Difficulties: A Randomized Controlled Trial

Children with low (pre-)literacy skills may benefit from individual tutoring during the early phases of learning to read. Dutch at-risk students from 13 schools received in first and second grade a computerized reading intervention, delivered by non-professional tutors at school. Digital logs indicated that treatment integrity was lower than intended; therefore, the intervention group was subdivided using a completion criterion. Third grade assessments revealed that the subgroup that had finished the program successfully (IF, N = 40) was able to read as fluent as the average reader, outperforming the subgroup that had not completely finished the program (InF, N = 31) as well as the group that had not worked with the program (controls, N = 66) on all reading measures. This study demonstrates that a well-implemented tutoring model can serve as a (cost-)effective complement to the classroom practice for beginning readers.

P 161. State-dependency of tDCS-induced plasticity in the motor cortex

Transcranial direct current stimulation (tDCS) is a non-invasive technique that can induce LTP/LTD-like plasticity in the stimulated area ( Fritsh, 2010 ). The electrical field generated by the stimulation modulates cortical activity according to polarity of the current: anodal stimulation (A-tDCS) has been shown to increase cortical excitability and cathodal stimulation (C-tDCS) to decrease cortical excitability ( [Bindman, 1964] , [Nitsche and Paulus, 2000] ). In this study we have combined tDCS with motor practice in order to evaluate if tDCS may enhance plasticity and learning through gating mechanisms or may trigger compensatory mechanisms of metaplasticity ( [Ziemann and Siebner, 2008] , [Pozo and Goda, 2010] ). To this aim, we ran two experiments: in the first experiment, the motor practice (MP) task consisted of fast thumb abduction movements (F-MP) of the left hand, which induce learning ( Muellbacher, 2002 ). In the second experiment, the motor practice task consisted of slow thumb abduction movements (S-MP), which do not induce learning. In both experiments, six blocks of MP (corresponding to 20 min) were performed while tDCS was delivered at 1.5 mA (electrode surface 25 cm 2 ; current density 0.06 mA/cm 2 ) on contralateral M1. Moreover, two blocks with fast thumb abduction were performed, one before and one after tDCS application. Peak acceleration in the fast thumb abduction blocks was used as measure of performance. Results showed a general learning effect when participants performed the F-MP task. Moreover, learning rates varied across stimulation conditions. A-tDCS reduced performance compared to sham in the early phase of learning, and C-tDCS increased performance compared to A-tDCS in the latter phase of learning. When participants performed the S-MP task, performance improved after A-tDCS, whereas no learning effect was found in the sham stimulation condition. Therefore, our results highlight that tDCS-induced plasticity in the motor cortex is state-dependent: When applied during a MP task that does not induce learning, A-tDCS increased performance. When applied during motor learning, A-tDCS interfered with performance, suggesting that the concurrent combination of tDCS with another plasticity-inducing protocol may trigger compensatory mechanisms of metaplasticity.

Impact of Outcome-Based Assessment on Student Learning and Faculty Instructional Practices

Increased accountability has been a catalyst for the reformation of curriculum and assessment practices in postsecondary schools throughout North America, including veterinary schools. There is a call for a shift in assessment practices in clinical rotations, from a focus on content to a focus on assessing student performance. Learning is subsequently articulated in terms of observable outcomes and indicators that describe what the learner can do after engaging in a learning experience. The purpose of this study was to examine the ways in which a competency-based program in an early phase of implementation impacted student learning and faculty instructional practices. Findings revealed that negative student perceptions of the assessment instrument's reliability had a detrimental effect on the face validity of the instrument and, subsequently, on students' engagement with competency-based assessment and promotion of student-centered learning. While the examination of faculty practices echoed findings from other studies that cited the need for faculty development to improve rater reliability and for a better data management system, our study found that faculty members' instructional practices improved through the alignment of instruction and curriculum. This snap-shot of the early stages of implementing a competency-based program has been instrumental in refining and advancing the program.

Decision making among HIV+ drug using men who have sex with men: A preliminary report from the Chicago Multicenter AIDS Cohort Study

HIV+ substance-dependent individuals (SDIs) make significantly poorer decisions than HIV– SDIs, but the neurocognitive mechanisms underlying this impairment have not been identified. We administered the Iowa Gambling Task (IGT), a measure of decision making under uncertain risk, and the Cups Task, a measure of decision making under specified risk, to a group of 56 HIV+ and 23 HIV– men who have sex with men (MSMs) with a history of substance dependence enrolled in the Multicenter AIDS Cohort Study. The IGT provides no explicit information regarding the contingencies for each possible choice, and the probability of each outcome remains ambiguous at least for the early trials; in contrast, the Cups Task provides explicit information about the probability of each outcome. The HIV+ group made significantly poorer decisions on the IGT than the HIV– group. Cups Task performance did not differ significantly between HIV– and HIV+ groups. Exploratory analyses of the IGT data suggested that HIV+ subjects tended to perform more poorly during the early learning phase when uncertainty about specific outcomes was greatest. Additionally, performance on the final two trial blocks was significantly correlated with Stroop Interference scores, suggesting that IGT performance is driven increasingly by executive control during the later portion of the task. Potential cognitive mechanisms to be explored in later studies are discussed, including impairment in implicit learning processing.

Cerebellar contributions to visuomotor adaptation and motor sequence learning: an ALE meta-analysis

Cerebellar contributions to motor learning are well-documented. For example, under some conditions, patients with cerebellar damage are impaired at visuomotor adaptation and at acquiring new action sequences. Moreover, cerebellar activation has been observed in functional MRI (fMRI) investigations of various motor learning tasks. The early phases of motor learning are cognitively demanding, relying on processes such as working memory, which have been linked to the cerebellum as well. Here, we investigated cerebellar contributions to motor learning using activation likelihood estimation (ALE) meta-analysis. This allowed us to determine, across studies and tasks, whether or not the location of cerebellar activation is constant across differing motor learning tasks, and whether or not cerebellar activation in early learning overlaps with that observed for working memory. We found that different regions of the anterior cerebellum are engaged for implicit and explicit sequence learning and visuomotor adaptation, providing additional evidence for the modularity of cerebellar function. Furthermore, we found that lobule VI of the cerebellum, which has been implicated in working memory, is activated during the early stages of explicit motor sequence learning. This provides evidence for a potential role for the cerebellum in the cognitive processing associated with motor learning. However, though lobule VI was activated across both early explicit sequence learning and working memory studies, there was no spatial overlap between these two regions. Together, our results support the idea of modularity in the formation of internal representations of new motor tasks in the cerebellum, and highlight the cognitive processing relied upon during the early phases of motor skill learning.

Change in Choice-Related Response Modulation in Area MT during Learning of a Depth-Discrimination Task is Consistent with Task Learning

What are the neural mechanisms underlying improvement in perceptual performance due to learning? A recent study using motion-direction discrimination suggested that perceptual learning is due to improvements in the "readout" of sensory signals in sensory-motor cortex and not to improvements in neural sensitivity of the sensory cortex. To test the generality of this hypothesis, we examined this in a similar but different task. We recorded from isolated neurons in the middle temporal (MT) area while monkeys were trained in a depth-discrimination task. Consistent with earlier reports using direction discrimination, we found no long-term improvement in MT neuron sensitivity to depth, although monkey performance improved over months with extensive training, even when taking out the effect of behavioral biases. We further addressed improvement in the readout of sensory signals by focusing on choice-related response modulation [choice probability (CP)]. CP increased with training, suggesting an improvement in the readout of sensory signals from MT. CP, however, correlated more strongly with lapse rate than psychophysical threshold, suggesting that changes in readout may be restricted to early phases of learning. To test how behavioral learning, as well as the magnitude of CP, transferred across visual fields, we measured CP variation in one hemifield after training monkeys on the depth-discrimination task in the opposite hemifield. CP was large from the beginning of training in the untrained hemifield, even though a small but significant improvement in sensitivity was observed behaviorally. Overall, our findings are consistent with the idea that increases in CP reflect task learning.

Primary motor cortex involvement in initial learning during visuomotor adaptation

Human motor behaviour is continually modified on the basis of errors between desired and actual movement outcomes. It is emerging that the role played by the primary motor cortex (M1) in this process is contingent upon a variety of factors, including the nature of the task being performed, and the stage of learning. Here we used repetitive TMS to test the hypothesis that M1 is intimately involved in the initial phase of sensorimotor adaptation. Inhibitory theta burst stimulation was applied to M1 prior to a task requiring modification of torques generated about the elbow/forearm complex in response to rotations of a visual feedback display. Participants were first exposed to a 30° clockwise (CW) rotation (Block A), then a 60° counterclockwise rotation (Block B), followed immediately by a second block of 30° CW rotation (A2). In the STIM condition, participants received 20s of continuous theta burst stimulation (cTBS) prior to the initial A Block. In the conventional (CON) condition, no stimulation was applied. The overt characteristics of performance in the two conditions were essentially equivalent with respect to the errors exhibited upon exposure to a new variant of the task. There were however, profound differences between the conditions in the latency of response preparation, and the excitability of corticospinal projections from M1, which accompanied phases of de-adaptation and re-adaptation (during Blocks B and A2). Upon subsequent exposure to the A rotation 24h later, the rate of re-adaptation was lower in the stimulation condition than that present in the conventional condition. These results support the assertion that primary motor cortex assumes a key role in a network that mediates adaptation to visuomotor perturbation, and emphasise that it is engaged functionally during the early phase of learning.

The concept of homology as a basis for evaluating developmental mechanisms: exploring selective attention across the life-span.

Research with human infants as well as non-human animal embryos and infants has consistently demonstrated the benefits of intersensory redundancy for perceptual learning and memory for redundantly specified information during early development. Studies of infant affect discrimination, face discrimination, numerical discrimination, sequence detection, abstract rule learning, and word comprehension and segmentation have all shown that intersensory redundancy promotes earlier detection of these properties when compared to unimodal exposure to the same properties. Here we explore the idea that such intersensory facilitation is evident across the life-span and that this continuity is an example of a developmental behavioral homology. We present evidence that intersensory facilitation is most apparent during early phases of learning for a variety of tasks, regardless of developmental level, including domains that are novel or tasks that require discrimination of fine detail or speeded responses. Under these conditions, infants, children, and adults all show intersensory facilitation, suggesting a developmental homology. We discuss the challenge and propose strategies for establishing appropriate guidelines for identifying developmental behavioral homologies. We conclude that evaluating the extent to which continuities observed across development are homologous can contribute to a better understanding of the processes of development.

L-DOPA changes ventral striatum recruitment during motor sequence learning in Parkinson's disease

We previously reported a differential effect of dopaminergic medication across the time course of motor sequence learning in early stage Parkinson's (PD) patients [1]. There was a medication-associated impairment specific to the early phase of learning. In the current study, we investigated the BOLD responses associated with this deleterious medication effect on motor sequence learning. We hypothesized that levodopa (l-DOPA) would negatively affect the recruitment of the ventral striatal circuitry during the early phase of learning. Seventeen early stage PD patients ON and OFF l-DOPA and 21 healthy control participants performed an explicit motor sequence learning task inside the MRI scanner. We observed sequence learning-specific activation during the early phase in the ventral putamen for controls and PD OFF but not for PD ON l-DOPA. A comparison of activation between PD OFF and PD ON showed that activation within the ventral putamen was decreased in PD ON compared to PD OFF. The extent of the l-DOPA associated activation decrease in the ventral putamen showed a small, positive correlation with the degree of sequence learning performance decrease in the early phase of learning (r=0.45–0.54 across measures, p<0.05, one-tailed). These findings provide evidence for the negative effects of l-DOPA in PD patients on the ventral putamen circuitry involved in early motor sequence learning, and provide support for a role of this structure in the sequence learning process.

A Tribute to Charlie Chaplin: Induced Positive Affect Improves Reward-Based Decision-Learning in Parkinson’s Disease

Reward-based decision-learning refers to the process of learning to select those actions that lead to rewards while avoiding actions that lead to punishments. This process, known to rely on dopaminergic activity in striatal brain regions, is compromised in Parkinson’s disease (PD). We hypothesized that such decision-learning deficits are alleviated by induced positive affect, which is thought to incur transient boosts in midbrain and striatal dopaminergic activity. Computational measures of probabilistic reward-based decision-learning were determined for 51 patients diagnosed with PD. Previous work has shown these measures to rely on the nucleus caudatus (outcome evaluation during the early phases of learning) and the putamen (reward prediction during later phases of learning). We observed that induced positive affect facilitated learning, through its effects on reward prediction rather than outcome evaluation. Viewing a few minutes of comedy clips served to remedy dopamine-related problems associated with frontostriatal circuitry and, consequently, learning to predict which actions will yield reward.

Territorial song sparrows tolerate juveniles during the early song-learning phase

Avian song learning is an important model system for understanding vocal learning in humans and other animals. Laboratory studies indicate that social interactions are critical for song learning, but field observations show that territorial males are aggressive to intruders, raising the question of whether young birds are tolerated, much less tutored in the wild. We examined how adult song sparrows (Melospiza melodia) treat juvenile and adult intruders during different seasons important for song learning—summer, autumn, and spring—using taxidermic mounts and song playback. Territorial adults responded aggressively to adult intruders throughout the year. Adults were tolerant of juvenile intruders in the summer, displayed somewhat reduced aggression in the autumn, but treated juveniles like adult intruders by the spring. In the summer and autumn trials, wild juveniles approached our simulated ‘‘interactions’’ between subjects and adult mounts; these wild juveniles were also tolerated, even at close distances. That juveniles can and do closely approach adults during the early sensitive phase of song learning suggests that direct interactions with adults are possible and might be important for learning. In contrast, since young birds are treated aggressively in early spring, most late song learning likely happens through eavesdropping or long-distance singing interactions.