Translational validity of neuropsychological tasks of sustained attention between rodents and humans: A systematic review of three rodent tasks.

Atypical sustained attention is a symptom in a number of neurological and psychological conditions. Investigations into its neural underpinnings are required for improved management and treatment. Rodents are useful in investigating the neurobiology underlying atypical sustained attention and several rodent tasks have been developed for use in touchscreen testing platforms that mimic methodology used in human clinical attention assessment. This systematic review was conducted to assess how translatable these rodent tasks are to equivalent clinical human tasks. Studies using the rodent Continuous Performance Task (rCPT), Sustained Attention Task (SAT), and 5-choice CPT (5C-CPT) were sought and screened. Included in the review were 138 studies, using the rCPT (n = 21), SAT (n = 90), and 5C-CPT (n = 27). Translatability between rodent and human studies was assessed based on (1) methodological similarity, (2) performance similarity, and (3) replication of results. The 5C-CPT was found to be the most translatable cross-species paradigm with good utility, while the rCPT and SAT require adaptation and further development to meet these translatability benchmarks. With greater replication and more consistent results, greater confidence in the translation of sustained attention results between species will be engendered.

Chronic ecologically relevant stress effects on reverse-translated touchscreen assays of reward responsivity and attentional processes in male rats: Implications for depression.

Stagnation in the development of novel therapeutic strategies for treatment-resistant depression has encouraged continued interest in improving preclinical methods. One tactic prioritizes the reverse translation of behavioral tasks developed to objectively quantify depressive phenotypes in patient populations for their use in laboratory animals via touchscreen technology. After cross-species concordance in task outcomes under healthy conditions is confirmed, construct validity can be further enhanced by identifying environmental stressors that reliably produce deficits in task performance that resemble those in depressive participants. The present studies characterized in male rats the ability of two chronic ecologically relevant stressors, inescapable ice water or isolated restraint, to produce depressive-like behavioral phenotypes in the Probabilistic Reward Task (PRT) and Psychomotor Vigilance Task (PVT). These tasks previously have been reverse-translated using touchscreen technology for rodents and nonhuman primates to objectively quantify, respectively, reward responsivity (anhedonia) and attentional processes (impaired cognitive function), each of which are core features of major depressive disorder. In the PRT, both inescapable ice water and isolated restraint produced persistent anhedonic phenotypes compared to non-stressed control performance (i.e., significantly blunted response bias for the richly rewarded stimulus). In the PVT, both chronic stressors impaired attentional processing, revealed by increases in titrated reaction times; however, these deficits largely subsided by the end of the chronic condition. Taken together, these findings confirm the ability of reverse-translated touchscreen tasks to effectively generate behavioral phenotypes that exhibit expected deficits in performance outcomes following exposure to chronic ecologically relevant stress. In turn, this approach is well positioned to appraise the ability of candidate therapeutics to attenuate or reverse such behavioral deficits and, thereby, contribute to preclinical medications development for treatment-resistant depression.

Poly (I:C)-induced maternal immune activation generates impairment of reversal learning performance in offspring.

Maternal immune activation (MIA) induces a variety of behavioral and brain abnormalities in offspring of rodent models, compatible with neurodevelopmental disorders, such as schizophrenia or autism. However, it remains controversial whether MIA impairs reversal learning, a basic expression of cognitive flexibility that seems to be altered in schizophrenia. In the present study, MIA was induced by administration of a single dose of polyriboinosinic-polyribocytidylic acid (Poly (I:C) (5 mg/kg i.p.)) or saline to mouse pregnant dams in gestational day (GD) 9.5. Immune activation was monitored through changes in weight and temperature. The offspring were evaluated when they reached adulthood (8 weeks) using a touchscreen-based system to investigate the effects of Poly (I:C) on discrimination and reversal learning performance. After an initial pre-training, mice were trained to discriminate between two different stimuli, of which only one was rewarded (acquisition phase). When the correct response reached above 80% values for two consecutive days, the images were reversed (reversal phase) to assess the adaptation capacity to a changing environment. Maternal Poly (I:C) treatment did not interfere with the learning process but induced deficits in reversal learning compared to control saline animals. Thus, the accuracy in the reversal phase was lower, and Poly (I:C) animals required more sessions to complete it, suggesting impairments in cognitive flexibility. This study advances the knowledge of how MIA affects behavior, especially cognitive domains that are impaired in schizophrenia. The findings support the validity of the Poly (I:C)-based MIA model as a tool to develop pharmacological treatments targeting cognitive deficits associated with neurodevelopmental disorders.

The longitudinal behavioral effects of acute exposure to galactic cosmic radiation in female C57BL/6J mice: Implications for deep space missions, female crews, and potential antioxidant countermeasures.

Galactic cosmic radiation (GCR) is an unavoidable risk to astronauts that may affect mission success. Male rodents exposed to 33-beam-GCR (33-GCR) show short-term cognitive deficits but reports on female rodents and long-term assessment are lacking. We asked: What are the longitudinal behavioral effects of 33-GCR on female mice? Also, can an antioxidant/anti-inflammatory compound (CDDO-EA) mitigate the impact of 33-GCR? Mature (6-month-old) C57BL/6J female mice received CDDO-EA (400 µg/g of food) or a control diet (vehicle, Veh) for 5 days and Sham-irradiation (IRR) or whole-body 33-GCR (0.75Gy) on the 4th day. Three-months post-IRR, mice underwent two touchscreen-platform tests: (1) location discrimination reversal (tests behavior pattern separation and cognitive flexibility, abilities reliant on the dentate gyrus) and (2) stimulus-response learning/extinction. Mice then underwent arena-based behavior tests (e.g. open field, 3-chamber social interaction). At the experiment's end (14.25-month post-IRR), an index relevant to neurogenesis was quantified (doublecortin-immunoreactive [DCX+] dentate gyrus immature neurons). Female mice exposed to Veh/Sham vs. Veh/33-GCR had similar pattern separation (% correct to 1st reversal). There were two effects of diet: CDDO-EA/Sham and CDDO-EA/33-GCR mice had better pattern separation vs. their respective control groups (Veh/Sham, Veh/33-GCR), and CDDO-EA/33-GCR mice had better cognitive flexibility (reversal number) vs. Veh/33-GCR mice. One radiation effect/CDDO-EA countereffect also emerged: Veh/33-GCR mice had slower stimulus-response learning (days to completion) vs. all other groups, including CDDO-EA/33-GCR mice. In general, all mice showed normal anxiety-like behavior, exploration, and habituation to novel environments. There was also a change relevant to neurogenesis: Veh/33-GCR mice had fewer DCX+ dentate gyrus immature neurons vs. Veh/Sham mice. Our study implies space radiation is a risk to a female crew's longitudinal mission-relevant cognitive processes and CDDO-EA is a potential dietary countermeasure for space-radiation CNS risks.

The flashy escape: support for dynamic flash coloration as anti-predator defence.

Dynamic flash coloration is a type of antipredator coloration where intermittently appearing colour patterns in moving animals misdirect predator attacks by obscuring the precise location and trajectory of the moving prey. Birds and butterflies with differing dorsoventral wing coloration or iridescent surface structures may potentially benefit from such effects. However, we lack an understanding of what makes for an effective dynamic flash colour design and how much it benefits the carrier. Here, we test the effect of colour flashing using small passerine birds preying upon colourful, moving, virtual 'prey' stimuli on a touchscreen. We show that at fast speeds, green-to-blue flashing colour patterns can reduce the likelihood of pecks hitting the target, induce greater error in targeting accuracy and increase the number of pecks at a stimulus relative to similarly coloured non-flashing targets. Our results support the idea that dynamic flash coloration can deflect predatory attacks at fast speeds, but the effect may be the opposite when moving slowly.

Can touchscreens replace teachers? Chinese children's character learning from a touchscreen-based app, video, or face-to-face instruction.

Given the increasing prevalence of touchscreen devices that are intended for educational purposes, this study explored children's transfer of learning from touchscreen media compared with video and offline face-to-face learning. A total of 76 5- and 6-year-old Chinese kindergarten children (M = 68.21 months, SD = 3.57, range = 62-76; 30 boys and 46 girls) were randomly assigned to learn eight Chinese characters using a touchscreen-based app, using a video, or through face-to-face interaction. Learning was measured via the recall task scores, recognition task scores, recall efficiency, and recognition efficiency. The results revealed that children's recall and recognition task scores improved when learning took place using the touchscreen or face-to-face interaction. Children's recall efficiency and recognition efficiency were strongest in the face-to-face condition, followed by the touchscreen condition and then the video condition. The effects of instructional format on children's recall and recognition scores and recall efficiency were moderated by age; younger children's recall and recognition scores in the face-to-face condition and the touchscreen condition were significantly higher than in the video condition, yet older children's recall and recognition scores did not differ between conditions. However, for recall efficiency, younger children's recall efficiency in the face-to-face condition and the touchscreen condition was significantly higher than in the video condition; older children's recall efficiency in the face-to-face condition was higher than in both the touchscreen condition and the video condition. In conclusion, both face-to-face interaction and a touchscreen-based app were helpful ways for children to learn Chinese characters compared with video, but face-to-face learning showed advantages over touchscreen learning in recall efficiency for older children.

Dragging but not tapping promotes preschoolers' numerical estimating with touchscreens.

When solving mathematical problems, young children will perform better when they can use gestures that match mental representations. However, despite their increasing prevalence in educational settings, few studies have explored this effect in touchscreen-based interactions. Thus, we investigated the impact on young children's performance of dragging (where a continuous gesture is performed that is congruent with the change in number) and tapping (involving a discrete gesture that is incongruent) on a touchscreen device when engaged in a continuous number line estimation task. By examining differences in the set size and position of the number line estimation, we were also able to explore the boundary conditions for the superiority effect of congruent gestures. We used a 2 (Gesture Type: drag or tap) × 2 (Set Size: Set 0-10 or Set 0-20) × 2 (Position: left of midpoint or right of midpoint) mixed design. A total of 70 children aged 5 and 6 years (33 girls) were recruited and randomly assigned to either the Drag or Tap group. We found that the congruent gesture (drag) generally facilitated better performance with the touchscreen but with boundary conditions. When completing difficult estimations (right side in the large set size), the Drag group was more accurate, responded to the stimulus faster, and spent more time manipulating than the Tap group. These findings suggest that when children require explicit scaffolding, congruent touchscreen gestures help to release mental resources for strategic adjustments, decrease the difficulty of numerical estimation, and support constructing mental representations.

A jsPsych touchscreen extension for behavioral research on touch-enabled interfaces.

Online experiments are increasingly gaining traction in the behavioral sciences. Despite this, behavioral researchers have largely continued to use keyboards as the primary input devices for such online studies, overlooking the ubiquity of touchscreens in everyday use. This paper presents an open-source touchscreen extension for jsPsych, a JavaScript framework designed for conducting online experiments. We additionally evaluated the touchscreen extension assessing whether typical behavioral findings from two distinct perceptual decision-making tasks - the random-dot kinematogram and the Stroop task - can similarly be observed when administered via touchscreen devices compared to keyboard devices. Our findings indicate similar performance metrics for each paradigm between the touchscreen and keyboard versions of the experiments. Specifically, we observe similar psychometric curves in the random-dot kinematogram across the touchscreen and keyboard versions. Similarly, in the Stroop task, we detect significant task, congruency, and sequential congruency effects in both experiment versions. We conclude that our open-source touchscreen extension serves as a promising tool for data collection in online behavioral experiments on forced-choice tasks.

Neuroanatomical and cognitive biomarkers of alpha-synuclein propagation in a mouse model of synucleinopathy prior to onset of motor symptoms.

Significant evidence suggests that misfolded alpha-synuclein (aSyn), a major component of Lewy bodies, propagates in a prion-like manner contributing to disease progression in Parkinson's disease (PD) and other synucleinopathies. In fact, timed inoculation of M83 hemizygous mice with recombinant human aSyn preformed fibrils (PFF) has shown symptomatic deficits after substantial spreading of pathogenic alpha-synuclein, as detected by markers for the phosphorylation of S129 of aSyn. However, whether accumulated toxicity impact human-relevant cognitive and structural neuroanatomical measures is not fully understood. Here we performed a single unilateral striatal PFF injection in M83 hemizygous mice, and using two assays with translational potential, ex vivo magnetic resonance imaging (MRI) and touchscreen testing, we examined the combined neuroanatomical and behavioral impact of aSyn propagation. In PFF-injected mice, we observed widespread atrophy in bilateral regions that project to or receive input from the injection site using MRI. We also identified early deficits in reversal learning prior to the emergence of motor symptoms. Our findings highlight a network of regions with related cellular correlates of pathology that follow the progression of aSyn spreading, and that affect brain areas relevant for reversal learning. Our experiments suggest that M83 hemizygous mice injected with human PFF provides a model to understand how misfolded aSyn affects human-relevant pre-clinical measures and suggest that these pre-clinical biomarkers could be used to detect early toxicity of aSyn and provide better translational measures between mice and human disease.

Validation of a touchscreen probabilistic reward task for mice: A reverse-translated assay with cross-species continuity.

The Probabilistic Reward Task (PRT) is a laboratory-based technique used to objectively quantify responsivity to reward. The PRT was initially designed to identify reinforcement learning deficits in clinical populations and subsequently was reverse-translated for use in preclinical studies with rats and monkeys. In this task, subjects make visual discriminations and asymmetric probabilistic contingencies are arranged such that correct responses to one stimulus (rich) are reinforced more often than correct responses to the other (lean). Numerous studies have demonstrated that healthy subjects reliably develop a response bias toward the richly rewarded stimulus, whereas humans with anhedonia and laboratory animals with a history of chronic stress exhibit a blunted response bias. This is important because anhedonia, the loss of responsivity to previously rewarding stimuli, is a behavioral phenotype that is a cardinal feature of multiple neuropsychiatric conditions and is without approved pharmacotherapeutic options. To aid in addressing this critical treatment gap, this report describes validation of the first PRT designed for mice, which are a commonly utilized species in preclinical research toward neuropsychiatric medications development. Results reveal orderly psychophysical functions in response to asymmetric probabilistic contingencies in mice, with signal detection outcomes comparable to previous PRT findings in humans, rats, and monkeys. Taken together, such robust cross-species continuity in task performance confirms that the mouse is well-positioned to serve in bidirectional research efforts between human and animal laboratories. These efforts may accelerate the development of treatment options for anhedonia in the different neuropsychiatric conditions in which it is prominent.

Visual discrimination and inhibitory control deficits in mouse models of Down syndrome: A pilot study using rodent touchscreen technology.

Several non-verbal cognitive and behavioral tests have been developed to assess learning deficits in humans with Down syndrome (DS). Here we used rodent touchscreen paradigms in adult male mice to investigate visual discrimination (VD) learning and inhibitory control in the Dp(16)1/Yey (C57BL/6J genetic background), Ts65Dn (mixed B6 X C3H genetic background) and Ts1Cje (C57BL/6J genetic background) mouse models of DS. Dp(16)1/Yey and Ts1Cje models did not exhibit motivation or learning deficits during early pre-training, however, Ts1Cje mice showed a significant learning delay after the introduction of the incorrect stimulus (late pre-training), suggesting prefrontal cortex defects in this model. Dp(16)1/Yey and Ts1Cje mice display learning deficits in VD but these deficits were more pronounced in the Dp(16)1/Yey model. Both models also exhibited compulsive behavior and abnormal cortical inhibitory control during Extinction compared to WT littermates. Finally, Ts65Dn mice outperformed WT littermates in pre-training stages by initiating a significantly higher number of trials due to their hyperactive behavior. Both Ts65Dn and WT littermates showed poor performance during late pre-training and were not tested in VD. These studies demonstrate significant learning deficits and compulsive behavior in the Ts1Cje and Dp(16)1/Yey mouse models of DS. They also demonstrate that the mouse genetic background (C57BL/6J vs. mixed B6 X C3H) and the absence of hyperactive behavior are key determinants of successful learning in touchscreen behavioral testing. These data will be used to select the mouse model that best mimics cognitive deficits in humans with DS and evaluate the effects of future therapeutic interventions.

Dorsomedial striatum, but not dorsolateral striatum, is necessary for rat category learning.

Categorization is an adaptive cognitive function that allows us to generalize knowledge to novel situations. Converging evidence from neuropsychological, neuroimaging, and neurophysiological studies suggest that categorization is mediated by the basal ganglia; however, there is debate regarding the necessity of each subregion of the basal ganglia and their respective functions. The current experiment examined the roles of the dorsomedial striatum (DMS; homologous to the head of the caudate nucleus) and dorsolateral striatum (DLS; homologous to the body and tail of the caudate nucleus) in category learning by combining selective lesions with computational modeling. Using a touchscreen apparatus, rats were trained to categorize distributions of visual stimuli that varied along two continuous dimensions (i.e., spatial frequency and orientation). The tasks either required attention to one stimulus dimension (spatial frequency or orientation; 1D tasks) or both stimulus dimensions (spatial frequency and orientation; 2D tasks). Rats with NMDA lesions of the DMS were impaired on both the 1D tasks and 2D tasks, whereas rats with DLS lesions showed no impairments. The lesions did not affect performance on a discrimination task that had the same trial structure as the categorization tasks, suggesting that the category impairments effected processes relevant to categorization. Model simulations were conducted using a neural network to assess the effect of the DMS lesions on category learning. Together, the results suggest that the DMS is critical to map category representations to appropriate behavioral responses, whereas the DLS is not necessary for categorization.

Capuchin monkeys learn to use information equally well from individual exploration and social demonstration.

The limited evidence of complex culture in non-human primates contrasts strikingly with human behaviour. This may be because non-human primates fail to use information acquired socially as effectively as they use information acquired individually. Here, monkeys were trained on a stimulus discrimination task with a win-stay, lose-shift (WSLS) reward structure. In a social learning condition, the experimenter performed an information trial by choosing between the available stimuli; in an individual condition, monkeys made this choice themselves. The monkeys' subsequent test trials displayed the same stimulus array. They were rewarded for repetition of rewarded ('win-stay') and avoidance of unrewarded ('lose-shift') information trial selections. Nine monkeys reached our pre-determined performance criterion on the initial two-stimulus stage. Their ability to generalise the WSLS strategy was then evaluated by transfer to a three-stimulus stage. Minimal differences were found in information use between the social and individual conditions on two-stimuli. However, a bias was found towards repetition of the information trial, regardless of information source condition or whether the information trial selection was rewarded. Proficient subjects were found to generalise the strategy to three-stimuli following rewarded information trials, but performed at chance on unrewarded. Again, this was not found to vary by source condition. Overall, results suggest no fundamental barrier to non-human primates' use of information from a social source. However, the apparent struggle to learn from the absence of rewards hints at a difficulty with using information acquired from unsuccessful attempts; this could be linked to the limited evidence for cumulative culture in non-human primates.

Stepwise learning of compound multidimensional visual stimuli by sorting out the dimensions of which they are composed in pigeons.

Pigeons (Columba livia) were trained on a stage-wise go/no-go visual discrimination task. Sixteen compound stimuli were created from all the possible combinations of two stimulus values from four separable visual dimensions: shape (circle/square), size (large/small), line orientation (horizontal/vertical), and brightness (dark/light). Starting with 1 S + and 1 S - that differed in all four-dimensional values, in our later steps, we added S - stimuli one by one, sharing at first 1, then 2, and then 3 dimensions with S + by sorting them out. When the pigeons had clearly shown attending to each of four dimensions, we presented all 16 stimuli. In this last stage, the pigeons correctly rejected most of the S - stimuli despite seeing them for the first time. Thus, to discriminate 16 unique multidimensional stimuli, it was not necessary to learn all of them as compound stimuli in such an approach. However, the 4 learnt dimensions did not give fully comprehensive information about all the new and unique compound stimuli presented in the last stage. Mistakes were associated with similarity to S + and with the order of dimensional learning. Most pigeons made mistakes in the discrimination of S - stimuli that shared 3 (some shared two) dimensions with S + . The knowledge of the first-learned dimension of compound stimuli was less reliable than the dimensions learned in the last stage.

Lab cognition going wild: Implementing a new portable touchscreen system in vervet monkeys.

Touchscreen technology has provided researchers with opportunities to conduct well-controlled cognitive tests with captive animals, allowing researchers to isolate individuals, select participants based on specific traits, and control aspects of the environment. In this study, we aimed to investigate the potential utility of touchscreen technology for the study of cognition in wild vervet monkeys. We assessed the viability of touchscreen testing by comparing rates of participation between wild and sanctuary-housed vervets. Additionally, we compared performance on a simple associative learning task in order to verify that wild participants are able to engage meaningfully with a touchscreen task presented in their natural environment. We presented eight groups of vervet monkeys (four wild and four sanctuary groups, totalling 240 individuals) with a portable touchscreen device. The touchscreen displayed tasks in which food rewards could be gained by touching a stimulus displayed on the screen. We assessed individuals' likelihood of interacting with the touchscreen, their frequency of participation, and their performance on a simple associative learning task. We found that sanctuary-housed monkeys were more likely to interact with the touchscreen. Participation in wild vervet monkeys was influenced by sex and age. However, monkeys in the two contexts (sanctuary vs. wild) did not differ in their performance on a simple associative learning task. This study demonstrates that touchscreen technology can be successfully deployed in a population of wild primates. This gives us a starting point to test animal cognition under natural conditions that include varying group composition, environmental challenges and ongoing activities such as foraging, which are challenging to recreate in captivity. While rates of participation were lower than those found in captivity, reasonable sample sizes can be achieved, and wild primates can successfully learn touchscreen tasks in a manner comparable to their captive counterparts.

Swipe, tap, read? Unveiling the effects of Touchscreen devices on Emergent Literacy Development in preschoolers.

Emergent literacy skills are vital for children's reading and writing development. While touchscreen devices have been linked to enhanced emergent literacy in developed countries, their impact in low- and middle-income countries (LMICs), with limited access to quality apps, is underexplored. Thailand, classified as an upper-middle-income country, presents a unique context with its specific challenges in educational technology, which have not been extensively studied. This study examined the relationship between touchscreen device usage and emergent literacy development in Thai preschool children. Using a cross-sectional design, we analyzed data from 317 Thai children aged 5-6 years, assessing their emergent literacy skills and examining the association with touchscreen device usage through logistic regression analysis. Our findings showed that 79.5% of participants engaged with touchscreen devices, and there was an observed trend suggesting that exclusive tablet users might exhibit enhanced phonological awareness, letter naming, and rapid automatized naming skills. However, these potential improvements did not reach statistical significance when primary caregiver characteristics were taken into account. Our findings highlight the complexity of this relationship and underscore the need for further research to elucidate the potential influences of application quality and screen time engagement on emergent literacy, particularly in LMICs.

Frictional dermatitis from touchscreen contact.

Frictional dermatitis occurs after prolonged or repetitive physical contact of the skin with a surface and usually presents as a pediatric or occupational dermatosis. A 10-year-old girl presented with painful erythematous, edematous plaques, and macules on the fingertips within 24 h of playing a game requiring her fingers to repeatedly slide across a touch screen for about 45 min. The repetitive frictional pressure and contact over a short period of time between the fingertips and the touch screen contributed to the onset of dermatitis in this case.

Effect of icon size, icon position and sex on clicking motion when operating smartphones with single hand.

Nowadays, increasingly more situations exist where smartphones are operated with one hand, requiring an in-depth understanding of human-computer interaction in single-hand scenarios. 104 volunteers (57 men, 47 women) participated in this study. We aimed to explore thumb movements with the right and left hand on smartphone touchscreens at different icon sizes (50, 80, 110 and 140 rpx) in different operation areas (a 4*7 icon matrix). The results partially conformed to Fitts' Law. The movement time (MT) significantly increased as the icon size decreased, but this effect was not found over 110 rpx. The MT increased with distance in the vertical direction, but icons with the same horizontal distance had different MTs, indicating that one-handed operation restricted the click on the same side. Additionally, subjects rated 140 rpx better than other sizes, and men clicked faster than women. Suggestions regarding one-handed interface design for different hands of different sexes are provided.Practitioner summary: This study investigated how icon size, position and sex influenced one-thumb click usability on touch-screen mobile phones with different hands of different sexes. The results indicate single-hand operation partially conformed to Fitts' Law. We suggested the most economical and comfortable size and the fast operation area in one-handed interface design.Abbreviations: MT: movement time; ID: index of difficulty; RPX: responsive pixel; NASA-TLX: task load index of National Aeronautics and Space Administration; ANOVA: analysis of variance.

Language in educational apps for pre-schoolers. A comparison of grammatical constructions and psycholinguistic features in apps, books and child directed speech.

Language in touchscreen apps could be useful as an additional source of children's language input, alongside child directed speech (CDS) and books. Here we performed the first analysis of language in apps, as compared with books and CDS. We analysed language in 18 of the most popular educational apps targeting pre-schoolers and compared their language content to children's books and CDS with respect to types of constructions and psycholinguistic features of words. We found that apps contained lower frequency words and had lower lexical diversity compared to CDS, and shorter utterances compared to books. Apps may thus provide an enriched supplementary form of input for young children, due to containing less frequent words. However, apps do not expose children to a high proportion of questions and complex sentences, both of which are crucial for supporting child's development of structurally rich constructions.

Systemic D1-R and D2-R antagonists in non-human primates differentially impact learning and memory while impairing motivation and motor performance.

Dopamine (DA) modulates cognition in part via differential activation of D1 and D2 receptors within the striatum and prefrontal cortex, yet evidence for cognitive impairments stemming from DA blockade or deficiency is inconsistent. Given the predominance of D1 over D2 receptors (R) in the prefrontal cortex of primates, D1-R blockade should more strongly influence frontal executive function (including working memory), while D2-R blockade should impair processes more strongly associated with the dorsal striatum (including cognitive flexibility, and learning). To test how systemic DA blockade disrupts cognition, we administered D1-R and D2-R like antagonists to healthy monkeys while they performed a series of cognitive tasks. Two selective DA receptor antagonist drugs (SCH-23390 hydrochloride: D1/D5-R antagonist; or Eticlopride hydrochloride: D2/D3-R antagonist) or placebo (0.9% saline) were systemically administered. Four tasks were used: (1) 'visually guided reaching', to test response time and accuracy, (2) 'reversal learning', to test association learning and attention, (3) 'self-ordered sequential search' to test spatial working memory, and (4) 'delayed match to sample' to test object working memory. Increased reach response times and decreased motivation to work for liquid reward was observed with both the D1/D5-R and D2/D3-R antagonists at the maximum dosages that still enabled task performance. The D2/D3-R antagonist impaired performance in the reversal learning task, while object and spatial working memory performance was not consistently affected in the tested tasks for either drug. These results are consistent with the theory that systemic D2/D3-R antagonists preferentially influence striatum processes (cognitive flexibility) while systemic D1/D5-R administration is less detrimental to frontal executive function.