scholarly journals An implicit memory of errors limits human sensorimotor adaptation

2019 ◽  
Author(s):  
Scott T. Albert ◽  
Jihoon Jang ◽  
Hannah Sheahan ◽  
Lonneke Teunissen ◽  
Koenraad Vandevoorde ◽  
...  
Keyword(s):  
Implicit Learning ◽  
Motor Adaptation ◽  
Learning System ◽  
Second Order Statistics ◽  
Error Sensitivity ◽  
Implicit System ◽  
Extended Practice ◽  
History Of ◽  
Residual Errors ◽  
The Brain

AbstractAfter extended practice, motor adaptation reaches a limit in which learning appears to stop, despite the fact that residual errors persist. What prevents the brain from eliminating the residual errors? Here we found that the adaptation limit was causally dependent on the second order statistics of the perturbation; when variance was high, learning was impaired and large residual errors persisted. However, when learning relied solely on explicit strategy, both the adaptation limit and its dependence on perturbation variability disappeared. In contrast, when learning depended entirely, or in part on implicit learning, residual errors developed. Residual errors in implicit performance were caused by variance-dependent modifications to error sensitivity, not forgetting. These observations are consisted with a model of learning in which the implicit system becomes more sensitive to error when errors are consistent, but forgets this memory of errors over time. Thus, residual errors in motor adaptation are a signature of the implicit learning system, caused by an error sensitivity that depends on the history of past errors.

scholarly journals Environmental consistency modulation of error sensitivity during motor adaptation is explicitly controlled

2020 ◽  
Vol 123 (1) ◽  
pp. 57-69 ◽  
Author(s):  
Guy Avraham ◽  
Matan Keizman ◽  
Lior Shmuelof
Keyword(s):  
Motor Adaptation ◽  
External Perturbation ◽  
Implicit Processes ◽  
Error Sensitivity ◽  
Attentional Resources ◽  
Implicit System ◽  
Feedback Sensitivity ◽  
Series Of Experiments ◽  
Human Participants ◽  
High Consistency

Motor adaptation, the adjustment of a motor output in face of changes in the environment, may operate at different rates. When human participants encounter repeated or consistent perturbations, their corrections for the experienced errors are larger compared with when the perturbations are new or inconsistent. Such modulations of error sensitivity were traditionally considered to be an implicit process that does not require attentional resources. In recent years, the implicit view of motor adaptation has been challenged by evidence showing a contribution of explicit strategies to learning. These findings raise a fundamental question regarding the nature of the error sensitivity modulation processes. We tested the effect of explicit control on error sensitivity in a series of experiments, in which participants controlled a screen cursor to virtual targets. We manipulated environmental consistency by presenting rotations in random (low consistency) or random walk (high consistency) sequences and illustrated that perturbation consistency affects the rate of adaptation, corroborating previous studies. When participants were instructed to ignore the cursor and move directly to the target, thus eliminating the contribution of explicit strategies, consistency-driven error sensitivity modulation was not detected. In addition, delaying the visual feedback, a manipulation that affects implicit learning, did not influence error sensitivity under consistent perturbations. These results suggest that increases of learning rate in consistent environments are attributable to an explicit rather than implicit process in sensorimotor adaptation. NEW & NOTEWORTHY The consistency of an external perturbation modulates error sensitivity and the motor response. The roles of explicit and implicit processes in this modulation are unknown. We show that when humans are asked to ignore the perturbation, they do not show increased error sensitivity in consistent environments. When the implicit system is manipulated by delaying feedback, sensitivity to a consistent perturbation does not change. Overall, our results suggest that consistency affects adaptation mainly through explicit control.

scholarly journals Measures of explicit and implicit in motor learning: what we know and what we don’t

2020 ◽  
Author(s):  
Jana Maresch ◽  
Liad Mudrik ◽  
Opher Donchin
Keyword(s):  
Cognitive Science ◽  
Implicit Learning ◽  
Time Constant ◽  
Motor Adaptation ◽  
Visuomotor Adaptation ◽  
Fast Time ◽  
Implicit System ◽  
Learning And Adaptation ◽  
Underlying Processes

Multiple different processes are known to contribute to sensorimotor learning, and adaptation tasks have been a key tool in characterizing these underlying processes. Recently, much interest has focused on quantifying the explicit and implicit components of motor adaptation using a variety of methods. The methods differ in their underlying assumptions and ideas. In some cases, they yield similar findings, in others they do not. We review the literature with a focus on the agreement and inconsistencies between different measures of explicit adaptation. Some aspects of explicit adaptation seem robust across different measurements: the fast time constant of the explicit system and the slow time constant of the implicit system, for instance. Other aspects seem to reflect quite differently across measures: for example, the extent to which explicit and implicit combine linearly. To help understand these differences, we explored ideas of explicit and implicit learning in the context of the larger field of cognitive science. We found that non-linearity and a possible bias in the measurements make explicit and implicit learning difficult to measure across different fields within cognitive science. We relate this back to the study of motor adaptation, arguing that the only way forward is through a strong experimental characterization of the phenomenology of our visuomotor adaptation and a rich set of models to test on it.

scholarly journals L2HGDH Missense Variant in a Cat with L-2-Hydroxyglutaric Aciduria

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 682
Author(s):  
Matthias Christen ◽  
Nils Janzen ◽  
Anne Fraser ◽  
Adrian C. Sewell ◽  
Vidhya Jagannathan ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Genetic Defect ◽  
Clinical Signs ◽  
Missense Variant ◽  
Microcytic Anemia ◽  
Abnormal Behavior ◽  
Functional Candidate Gene ◽  
History Of ◽  
The Brain ◽  
Hydroxyglutaric Acid

A 7-month-old, spayed female, domestic longhair cat with L-2-hydroxyglutaric aciduria (L-2-HGA) was investigated. The aim of this study was to investigate the clinical signs, metabolic changes and underlying genetic defect. The owner of the cat reported a 4-month history of multiple paroxysmal seizure-like episodes, characterized by running around the house, often in circles, with abnormal behavior, bumping into obstacles, salivating and often urinating. The episodes were followed by a period of disorientation and inappetence. Neurological examination revealed an absent bilateral menace response. Routine blood work revealed mild microcytic anemia but biochemistry, ammonia, lactate and pre- and post-prandial bile acids were unremarkable. MRI of the brain identified multifocal, bilaterally symmetrical and T2-weighted hyperintensities within the prosencephalon, mesencephalon and metencephalon, primarily affecting the grey matter. Urinary organic acids identified highly increased levels of L-2-hydroxyglutaric acid. The cat was treated with the anticonvulsants levetiracetam and phenobarbitone and has been seizure-free for 16 months. We sequenced the genome of the affected cat and compared the data to 48 control genomes. L2HGDH, coding for L-2-hydroxyglutarate dehydrogenase, was investigated as the top functional candidate gene. This search revealed a single private protein-changing variant in the affected cat. The identified homozygous variant, XM_023255678.1:c.1301A>G, is predicted to result in an amino acid change in the L2HGDH protein, XP_023111446.1:p.His434Arg. The available clinical and biochemical data together with current knowledge about L2HGDH variants and their functional impact in humans and dogs allow us to classify the p.His434Arg variant as a causative variant for the observed neurological signs in this cat.

scholarly journals Molecular evolutionary analysis of human primary microcephaly genes

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nashaiman Pervaiz ◽  
Hongen Kang ◽  
Yiming Bao ◽  
Amir Ali Abbasi
Keyword(s):  
Evolutionary History ◽  
Genetic Basis ◽  
Brain Size ◽  
Primate Species ◽  
Evolutionary Analysis ◽  
Australopithecus Afarensis ◽  
Primary Microcephaly ◽  
Modern Humans ◽  
History Of ◽  
The Brain

Abstract Background There has been a rapid increase in the brain size relative to body size during mammalian evolutionary history. In particular, the enlarged and globular brain is the most distinctive anatomical feature of modern humans that set us apart from other extinct and extant primate species. Genetic basis of large brain size in modern humans has largely remained enigmatic. Genes associated with the pathological reduction of brain size (primary microcephaly-MCPH) have the characteristics and functions to be considered ideal candidates to unravel the genetic basis of evolutionary enlargement of human brain size. For instance, the brain size of microcephaly patients is similar to the brain size of Pan troglodyte and the very early hominids like the Sahelanthropus tchadensis and Australopithecus afarensis. Results The present study investigates the molecular evolutionary history of subset of autosomal recessive primary microcephaly (MCPH) genes; CEP135, ZNF335, PHC1, SASS6, CDK6, MFSD2A, CIT, and KIF14 across 48 mammalian species. Codon based substitutions site analysis indicated that ZNF335, SASS6, CIT, and KIF14 have experienced positive selection in eutherian evolutionary history. Estimation of divergent selection pressure revealed that almost all of the MCPH genes analyzed in the present study have maintained their functions throughout the history of placental mammals. Contrary to our expectations, human-specific adoptive evolution was not detected for any of the MCPH genes analyzed in the present study. Conclusion Based on these data it can be inferred that protein-coding sequence of MCPH genes might not be the sole determinant of increase in relative brain size during primate evolutionary history.

Streptococcus pluranimalium meningoencephalitis in a horse

2021 ◽  
pp. 104063872110234
Author(s):  
Dah-Jiun Fu ◽  
Akhilesh Ramachandran ◽  
Craig Miller
Keyword(s):  
Ribosomal Rna ◽  
Cross Sections ◽  
Nucleotide Sequencing ◽  
Formalin Fixed Paraffin ◽  
Quarter Horse ◽  
Formalin Fixed Paraffin Embedded ◽  
History Of ◽  
The Brain ◽  
Gram Positive Cocci ◽  
Formalin Fixed

A 3-y-old, female Quarter Horse with a history of acute neurologic signs was found dead and was submitted for postmortem examination. Areas of petechial and ecchymotic hemorrhage were present on cross-sections of the cerebrum, cerebellum, and brainstem. Histologic examination of the brain revealed severe, purulent meningoencephalitis and vasculitis with a myriad of intralesional gram-positive cocci. Streptococcus pluranimalium was identified from formalin-fixed, paraffin-embedded tissue obtained from sites with active lesions by PCR and nucleotide sequencing of bacterial 16S ribosomal RNA. S. pluranimalium should be considered as a cause of meningoencephalitis in a horse.

scholarly journals A Rare Case of Spontaneous Arachnoid Cyst Rupture Presenting as Right Hemiplegia and Expressive Aphasia in a Pediatric Patient

Children ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 78
Author(s):  
Anne Bryden ◽  
Natalie Majors ◽  
Vinay Puri ◽  
Thomas Moriarty
Keyword(s):  
Cognitive Processing ◽  
Arachnoid Cyst ◽  
Memory Loss ◽  
Acute Onset ◽  
Word Finding ◽  
Outpatient Visits ◽  
The Family ◽  
History Of ◽  
Cyst Rupture ◽  
The Brain

This study examines an 11-year-old boy with a known history of a large previously asymptomatic arachnoid cyst (AC) presenting with acute onset of right facial droop, hemiplegia, and expressive aphasia. Shortly after arrival to the emergency department, the patient exhibited complete resolution of right-sided hemiplegia but developed headache and had persistent word-finding difficulties. Prior to symptom onset while in class at school, there was an absence of reported jerking movements, headache, photophobia, fever, or trauma. At the time of neurology consultation, the physical exam showed mildly delayed cognitive processing but was otherwise unremarkable. The patient underwent MRI scanning of the brain, which revealed left convexity subdural hematohygroma and perirolandic cortex edema resulting from ruptured left frontoparietal AC. He was evaluated by neurosurgery and managed expectantly. He recovered uneventfully and was discharged two days after presentation remaining asymptomatic on subsequent outpatient visits. The family express concerns regarding increased anxiety and mild memory loss since hospitalization.

Lyme Disease: Acute Focal Meningoencephalitis in a Child

PEDIATRICS ◽  
1988 ◽  
Vol 82 (6) ◽  
pp. 931-934
Author(s):  
HENRY M. FEDER ◽  
EDWIN L. ZALNERAITIS ◽  
LOUIS REIK
Keyword(s):  
Nervous System ◽  
Case Report ◽  
Lyme Disease ◽  
Signs And Symptoms ◽  
Brain Parenchyma ◽  
Tick Bite ◽  
System Involvement ◽  
History Of ◽  
Csf Pleocytosis ◽  
The Brain

Nervous system involvement in Lyme disease was originally described as meningitis, cranial neuritis, and radiculoneuritis,1-3 but Lyme disease can also involve the brain parenchyma. We describe a child whose first manifestation of Lyme disease was an acute, focal meningoencephalitis with signs and symptoms such as fever, headache, slurred speech, hemiparesis, seizure, and CSF pleocytosis. CASE REPORT A 7-year-old boy was hospitalized Aug 27, 1985, because of hemiparesis. Six weeks prior to admission he had vacationed at Old Lyme, CT. There was no history of rash or tick bite. He had been well until eight hours prior to admission when fever and headache developed.

Toluene-induced leukodystrophy from glue sniffing

2021 ◽  
pp. practneurol-2021-002942
Author(s):  
Yue Hui Lau ◽  
Ahmad Shahir Mawardi ◽  
Norzaini Rose Zain ◽  
Shanthi Viswanathan
Keyword(s):  
Basal Ganglia ◽  
Cognitive Decline ◽  
Early Recognition ◽  
Cerebellar Atrophy ◽  
Premature Mortality ◽  
History Of ◽  
The Brain

A 33-year-old man with a history of chronic toluene abuse through glue sniffing, developed tremors, cerebellar signs and cognitive decline. MR scan of the brain showed global cerebral and cerebellar atrophy with symmetrical T2-weighted hypointensities in the basal ganglia, thalami and midbrain. After stopping glue sniffing, his tremors, ataxia of gait, speech and cognition partially improved. Early recognition and intervention of toluene-induced leukodystrophy could prevent ongoing morbidity and premature mortality.

Senses of Vibration

2012 ◽  
Author(s):  
Shelly Trower
Keyword(s):  
Sensory Experience ◽  
Cultural Imaginary ◽  
Wide Range ◽  
History Of ◽  
The Senses ◽  
To Come ◽  
The Brain

The study of the senses has become a rich topic in recent years. Senses of Vibration explores a wide range of sensory experience and makes a decisive new contribution to this growing field by focussing not simply on the senses as such, but on the material experience - vibration - that underpins them. This is the first book to take the theme of vibration as central, offering an interdisciplinary history of the phenomenon and its reverberations in the cultural imaginary. It tracks vibration through the work of a wide range of writers, including physiologists (who thought vibrations in the nerves delivered sensations to the brain), physicists (who claimed that light, heat, electricity and other forms of energy were vibratory), spiritualists (who figured that spiritual energies also existed in vibratory form), and poets and novelists from Coleridge to Dickens and Wells. Senses of Vibration is a work of scholarship that cuts through a range of disciplines and will reverberate for many years to come.

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