Activator of KAT3 histone acetyltransferase family ameliorates a neurodevelopmental disorder phenotype in the syntaxin 1A ablated mouse model

Syntaxin-1A (stx1a) repression causes a neurodevelopmental disorder phenotype, low latent inhibition (LI) behavior, by disrupting 5-hydroxytryptaminergic (5-HTergic) systems. Herein, we discovered that lysine acetyltransferase (KAT) 3B increases stx1a neuronal transcription and TTK21, a KAT3 activator, induces stx1a transcription and 5-HT release in vitro. Furthermore, glucose-derived CSP-TTK21 could restore decreased stx1a expression, 5-HTergic systems in the brain, and low LI in stx1a (+/-) mice by crossing the blood-brain barrier, whereas the KAT3 inhibitor suppresses stx1a expression, 5-HTergic systems, and LI behaviors in wild-type mice. Finally, in wild-type and stx1a (-/-) mice treated with IKK inhibitors and CSP-TTK21, respectively, we show that KAT3 activator-induced LI improvement is a direct consequence of KAT3B-stx1a pathway, not a side effect. In conclusion, KAT3B can positively regulate stx1a transcription in neurons, and increasing neuronal stx1a expression and 5-HTergic systems by a KAT3 activator consequently improves the low LI behavior in the stx1a ablation mouse model.

Modulation of time in Parkinson's disease: a review and perspective on cognitive rehabilitation

Time cognition is an essential function of human life, and the impairment affects a variety of behavioral patterns. Neuropsychological approaches have been widely demonstrated that Parkinson's disease (PD) impairs time cognitive processing. Many researchers believe that time cognitive deficits are due to the basal ganglia, including the striatum or subthalamic nucleus, which is the pathomechanism of PD, and are considered to produce only transient recovery due to medication effects. In this perspective, we focus on a compensatory property of brain function based on the improved time cognition independent of basal ganglia recovery and an overlapping structure on the neural network based on an improved inhibitory system by time cognitive training, in patients with PD. This perspective may lead to restoring multiple functions through single function training.

Repetitive pulsed-wave ultrasound stimulation suppresses neural activity by modulating ambient GABA levels via effects on astrocytes

Ultrasound is highly biopermeable and can non-invasively penetrate deep into the brain. Stimulation with patterned low-intensity ultrasound can induce sustained inhibition of neural activity in humans and animals, with potential implications for research and therapeutics. Although mechanosensitive channels are involved, the cellular and molecular mechanisms underlying neuromodulation by ultrasound remain unknown. To investigate the mechanism of action of ultrasound stimulation, we studied the effects of two types of patterned ultrasound on synaptic transmission and neural network activity using whole-cell recordings in primary cultured hippocampal cells. Single-shot pulsed-wave (PW) or continuous-wave (CW) ultrasound had no effect on neural activity. By contrast, although repetitive CW stimulation also had no effect, repetitive PW stimulation persistently reduced spontaneous recurrent burst firing. This inhibitory effect was dependent on extrasynaptic-but not synaptic-GABAA receptors, and the effect was abolished under astrocyte-free conditions. Pharmacological activation of astrocytic TRPA1 channels mimicked the effects of ultrasound by increasing the tonic GABAA current induced by ambient GABA. Pharmacological blockade of TRPA1 channels abolished the inhibitory effect of ultrasound. These findings suggest that the repetitive PW low-intensity ultrasound used in our study does not have a direct effect on neural function but instead exerts its sustained neuromodulatory effect through modulation of ambient GABA levels via channels with characteristics of TRPA1, which is expressed in astrocytes.

Roles of the cerebellum and basal ganglia in temporal integration: Insights from a synchronized tapping task

OBJECTIVE

The aim of this study was to clarify the roles of the cerebellum and basal ganglia for temporal integration.

METHODS

We studied 39 patients with spinocerebellar degeneration (SCD), comprising spinocerebellar atrophy 6 (SCA6), SCA31, Machado-Joseph disease (MJD, also called SCA3), and multiple system atrophy (MSA). Thirteen normal subjects participated as controls. Participants were instructed to tap on a button in synchrony with isochronous tones. We analyzed the inter-tap interval (ITI), synchronizing tapping error (STE), negative asynchrony, and proportion of delayed tapping as indicators of tapping performance.

RESULTS

The ITI coefficient of variation was increased only in MSA patients. The standard variation of STE was larger in SCD patients than in normal subjects, especially for MSA. Negative asynchrony, which is a tendency to tap the button before the tones, was prominent in SCA6 and MSA patients, with possible basal ganglia involvement. SCA31 patients exhibited normal to supranormal performance in terms of the variability of STE, which was surprising.

CONCLUSIONS

Cerebellar patients generally showed greater STE variability, except for SCA31. The pace of tapping was affected in patients with possible basal ganglia pathology.

SIGNIFICANCE

Our results suggest that interaction between the cerebellum and the basal ganglia is essential for temporal processing. The cerebellum and basal ganglia and their interaction regulate synchronized tapping, resulting in distinct tapping pattern abnormalities among different SCD subtypes.

Age- and sex-related oculomotor manifestation of dopamine deficiency in Segawa disease

OBJECTIVE

To investigate the oculomotor manifestations of Segawa disease (SD), considered to represent mild dopamine deficiency and discuss their pathophysiological basis.

METHODS

We recorded visually- (VGS) and memory-guided saccade (MGS) tasks in 31 SD patients and 153 age-matched control subjects to study how basal ganglia (BG) dysfunction in SD evolves with age for male and female subjects.

RESULTS

SD patients were impaired in initiating MGS, showing longer latencies with occasional failure. Patients showed impaired ability to suppress reflexive saccades; saccades to cues presented in MGS were more frequent and showed a shorter latency than in control subjects. These findings were more prominent in male patients, particularly between 13 and 25 years. Additionally, male patients showed larger delay in MGS latency in trials preceded by saccades to cue than those unpreceded.

CONCLUSIONS

The findings can be explained by a dysfunction of the BG-direct pathway impinging on superior colliculus (SC) due to dopamine deficiency. The disturbed inhibitory control of saccades may be explained by increased SC responsivity to visual stimuli.

SIGNIFICANCE

Oculomotor abnormalities in SD can be explained by dysfunction of the BG inhibitory pathways reaching SC, with a delayed maturation in male SD patients, consistent with previous pathological/physiological studies.

The Pathophysiology of Gilles de la Tourette Syndrome: Changes in Saccade Performance by Low-Dose L-Dopa and Dopamine Receptor Blockers

AIM

To elucidate the pathophysiology of Gilles de la Tourette syndrome (GTS), which is associated with prior use of dopamine receptor antagonists (blockers) and treatment by L-Dopa, through saccade performance.

METHOD

In 226 male GTS patients (5-14 years), we followed vocal and motor tics and obsessive-compulsive disorder (OCD) after discontinuing blockers at the first visit starting with low-dose L-Dopa. We recorded visual- (VGS) and memory-guided saccades (MGS) in 110 patients and 26 normal participants.

RESULTS

At the first visit, prior blocker users exhibited more severe vocal tics and OCD, but not motor tics, which persisted during follow-up. Patients treated with L-Dopa showed greater improvement of motor tics, but not vocal tics and OCD. Patients with and without blocker use showed similarly impaired MGS performance, while patients with blocker use showed more prominently impaired inhibitory control of saccades, associated with vocal tics and OCD.

DISCUSSION

Impaired MGS performance suggested a mild hypodopaminergic state causing reduced direct pathway activity in the (oculo-)motor loops of the basal ganglia-thalamocortical circuit. Blocker use may aggravate vocal tics and OCD due to disinhibition within the associative and limbic loops. The findings provide a rationale for discouraging blocker use and using low-dose L-Dopa in GTS.

Comparison of the Molecular Motility of Tubulin Dimeric Isoforms: Molecular Dynamics Simulations and Diffracted X-ray Tracking Study

Tubulin has been recently reported to form a large family consisting of various gene isoforms; however, the differences in the molecular features of tubulin dimers composed of a combination of these isoforms remain unknown. Therefore, we attempted to elucidate the physical differences in the molecular motility of these tubulin dimers using the method of measurable pico-meter-scale molecular motility, diffracted X-ray tracking (DXT) analysis, regarding characteristic tubulin dimers, including neuronal TUBB3 and ubiquitous TUBB5. We first conducted a DXT analysis of neuronal (TUBB3-TUBA1A) and ubiquitous (TUBB5-TUBA1B) tubulin dimers and found that the molecular motility around the vertical axis of the neuronal tubulin dimer was lower than that of the ubiquitous tubulin dimer. The results of molecular dynamics (MD) simulation suggest that the difference in motility between the neuronal and ubiquitous tubulin dimers was probably caused by a change in the major contact of Gln245 in the T7 loop of TUBB from Glu11 in TUBA to Val353 in TUBB. The present study is the first report of a novel phenomenon in which the pico-meter-scale molecular motility between neuronal and ubiquitous tubulin dimers is different.

Abnormal saccade profiles in hereditary spinocerebellar degeneration reveal cerebellar contribution to visually guided saccades

OBJECTIVE

To study how the pathophysiology underlying hereditary spinocerebellar degeneration (spinocerebellar ataxia; SCA) with pure cerebellar manifestation evolves with disease progression using saccade recordings.

METHODS

We recorded visually- (VGS) and memory-guided saccade (MGS) task performance in a homogeneous population of 20 genetically proven SCA patients (12 SCA6 and eight SCA31 patients) and 19 normal controls.

RESULTS

For VGS but not MGS, saccade latency and amplitude were increased and more variable than those in normal subjects, which correlated with cerebellar symptom severity assessed using the International Cooperative Ataxia Rating Scale (ICARS). Parameters with significant correlations with cerebellar symptoms showed an aggravation after disease stage progression (ICARS > 50). The saccade velocity profile exhibited shortened acceleration and prolonged deceleration, which also correlated with disease progression. The main sequence relationship between saccade amplitude and peak velocity as well as saccade inhibitory control were preserved.

CONCLUSIONS

The cerebellum may be involved in initiating VGS, which was aggravated acutely during disease stage progression. Dysfunction associated with disease progression occurs mainly in the cerebellum and brainstem interaction but may also eventually involve cortical saccade processing.

SIGNIFICANCE

Saccade recording can reveal cerebellar pathophysiology underlying SCA with disease progression.

How do patients with Parkinson's disease and cerebellar ataxia read aloud? -Eye-voice coordination in text reading

Background

The coordination between gaze and voice is closely linked when reading text aloud, with the gaze leading the reading position by a certain eye-voice lead (EVL). How this coordination is affected is unknown in patients with cerebellar ataxia and parkinsonism, who show oculomotor deficits possibly impacting coordination between different effectors.

Objective

To elucidate the role of the cerebellum and basal ganglia in eye-voice coordination during reading aloud, by studying patients with Parkinson's disease (PD) and spinocerebellar degeneration (SCD).

Methods

Participants were sixteen SCD patients, 18 PD patients, and 30 age-matched normal subjects, all native Japanese speakers without cognitive impairment. Subjects read aloud Japanese texts of varying readability displayed on a monitor in front of their eyes, consisting of Chinese characters and hiragana (Japanese phonograms). The gaze and voice reading the text was simultaneously recorded by video-oculography and a microphone. A custom program synchronized and aligned the gaze and audio data in time.

Results

Reading speed was significantly reduced in SCD patients (3.53 ± 1.81 letters/s), requiring frequent regressions to compensate for the slow reading speed. In contrast, PD patients read at a comparable speed to normal subjects (4.79 ± 3.13 letters/s vs. 4.71 ± 2.38 letters/s). The gaze scanning speed, excluding regressive saccades, was slower in PD patients (9.64 ± 4.26 letters/s) compared to both normal subjects (12.55 ± 5.42 letters/s) and SCD patients (10.81 ± 4.52 letters/s). PD patients' gaze could not far exceed that of the reading speed, with smaller allowance for the gaze to proceed ahead of the reading position. Spatial EVL was similar across the three groups for all texts (normal: 2.95 ± 1.17 letters/s, PD: 2.95 ± 1.51 letters/s, SCD: 3.21 ± 1.35 letters/s). The ratio of gaze duration to temporal EVL was lowest for SCD patients (normal: 0.73 ± 0.50, PD: 0.70 ± 0.37, SCD: 0.40 ± 0.15).

Conclusion

Although coordination between voice and eye movements and normal eye-voice span was observed in both PD and SCD, SCD patients made frequent regressions to manage the slowed vocal output, restricting the ability for advance processing of text ahead of the gaze. In contrast, PD patients experience restricted reading speed primarily due to slowed scanning, limiting their maximum reading speed but effectively utilizing advance processing of upcoming text.

Quadripulse transcranial magnetic stimulation inducing long-term depression in healthy subjects may increase seizure risk in some patients with intractable epilepsy

Objective

This study aimed to assess the efficacy and safety of quadripulse transcranial magnetic stimulation-50 (QPS-50) in patients with intractable epilepsy.

Methods

Four patients were included in the study. QPS-50, which induces long-term depression in healthy subjects, was administered for 30 min on a weekly basis for 12 weeks. Patients' clinical symptoms and physiological parameters were evaluated before, during, and after the repeated QPS-50 period. We performed two control experiments: the effect in MEP (Motor evoked potential) size after a single QPS-50 session with a round coil in nine healthy volunteers, and a follow-up study of physiological parameters by repeated QPS-50 sessions in four other healthy participants.

Results

Motor threshold (MT) decreased during the repeated QPS-50 sessions in all patients. Epileptic symptoms worsened in two patients, whereas no clinical worsening was observed in the other two patients. In contrast, MT remained unaffected for 12 weeks in all healthy volunteers.

Conclusions

QPS-50 may not be effective as a treatment for intractable epilepsy.

Significance

In intractable epilepsy patients, administering repeated QPS-50 may paradoxically render the motor cortex more excitable, probably because of abnormal inhibitory control within the epileptic cortex. The possibility of clinical aggravation should be seriously considered when treating intractable epilepsy patients with non-invasive stimulation methods.

Early detection of cognitive decline in Alzheimer's disease using eye tracking

Background

Patients with Alzheimer's disease (AD) are known to exhibit visuospatial processing impairment, as reflected in eye movements from the early stages of the disease. We investigated whether the pattern of gaze exploration during visual tasks could be useful for detecting cognitive decline at the earliest stage.

Methods

Sixteen AD patients (age: 79.1 ± 7.9 years, Mini Mental State Examination [MMSE] score: 17.7 ± 5.3, mean ± standard deviation) and 16 control subjects (age: 79.4 ± 4.6, MMSE score: 26.9 ± 2.4) participated. In the visual memory task, subjects memorized presented line drawings for later recall. In the visual search tasks, they searched for a target Landolt ring of specific orientation (serial search task) or color (pop-out task) embedded among arrays of distractors. Using video-oculography, saccade parameters, patterns of gaze exploration, and pupil size change during task performance were recorded and compared between AD and control subjects.

Results

In the visual memory task, the number of informative regions of interest (ROIs) fixated was significantly reduced in AD patients compared to control subjects. In the visual search task, AD patients took a significantly longer time and more saccades to detect the target in the serial but not in pop-out search. In both tasks, there was no significant difference in the saccade frequency and amplitude between groups. On-task pupil modulation during the serial search task was decreased in AD. The number of ROIs fixated in the visual memory task and search time and saccade numbers in the serial search task differentiated both groups of subjects with high sensitivity, whereas saccade parameters of pupil size modulation were effective in confirming normal cognition from cognitive decline with high specificity.

Discussion

Reduced fixation on informative ROIs reflected impaired attentional allocation. Increased search time and saccade numbers in the visual search task indicated inefficient visual processing. Decreased on-task pupil size during visual search suggested decreased pupil modulation with cognitive load in AD patients, reflecting impaired function of the locus coeruleus. When patients perform the combination of these tasks to visualize multiple aspects of visuospatial processing, cognitive decline can be detected at an early stage with high sensitivity and specificity and its progression be evaluated.

Role of the subthalamic nucleus in perceiving and estimating the passage of time

Sense of time (temporal sense) is believed to be processed by various brain regions in a complex manner, among which the basal ganglia, including the striatum and subthalamic nucleus (STN), play central roles. However, the precise mechanism for processing sense of time has not been clarified. To examine the role of the STN in temporal processing of the sense of time by directly manipulating STN function by switching a deep brain stimulation (DBS) device On/Off in 28 patients with Parkinson's disease undergoing STN-DBS therapy. The test session was performed approximately 20 min after switching the DBS device from On to Off or from Off to On. Temporal sense processing was assessed in three different tasks (time reproduction, time production, and bisection). In the three temporal cognitive tasks, switching STN-DBS to Off caused shorter durations to be produced compared with the switching to the On condition in the time production task. In contrast, no effect of STN-DBS was observed in the time bisection or time reproduction tasks. These findings suggest that the STN is involved in the representation process of time duration and that the role of the STN in the sense of time may be limited to the exteriorization of memories formed by experience.

Hand-foot coordination is significantly influenced by motion direction in individuals with autism spectrum disorder

Generally, when individuals attempt to move two limbs rhythmically in the opposite direction (e.g., flex the left hand and extend the left foot along the sagittal plane), the movements tend to be instead performed in the same direction. This phenomenon, known as directional constraint, can be harnessed to examine the difficulties in movement coordination exhibited by most individuals with autism spectrum disorder (ASD). While such difficulties have already been investigated through standardized clinical assessments, they have not been examined through kinematic methods. Thus, we employed a clinical assessment scale in an experimentally controlled environment to investigate whether stronger directional constraint during the rhythmic movement of two limbs is more pronounced and associated with decreased movement coordination in individuals with ASD. ASD and typically developing (TD) participants were asked to rhythmically move two limbs either in the same or opposite directions. In addition, the coordination skills of participants were assessed using the Bruininks-Oseretsky Test of Motor Proficiency Second Edition (BOT-2). Subjects with ASD showed significantly stronger directional constraint than TD participants during the contralateral and ipsilateral movement of the hand and foot. According to the pooled data from both groups, participants who showed stronger directional constraint during these two movement conditions also exhibited poorer coordinated movement skills in the BOT-2. These results suggest that people with ASD may have difficulties in inhibiting the neural signals that synchronize the direction of inter-limb movements, thus resulting in coordination disabilities. LAY SUMMARY: Individuals with autism spectrum disorder (ASD) often exhibit difficulties in coordinated movements. We asked those with ASD and typically developing (TD) participants to move two limbs (e.g., left hand and left foot) either in the same or the opposite direction. Results demonstrated that participants with ASD had more difficulties in counteracting the tendency of their hand and foot to synchronously move in the same direction. Our findings suggested that difficulties to suppress synchronized movements of the hand and foot result in coordination disabilities.

Golgi stress induces upregulation of the ER-Golgi SNARE Syntaxin-5, altered βAPP processing, and Caspase-3-dependent apoptosis in NG108-15 cells

The involvement of secretory pathways and Golgi dysfunction in neuronal cells during Alzheimer's disease progression is poorly understood. Our previous overexpression and knockdown studies revealed that the intracellular protein level of Syntaxin-5, an endoplasmic reticulum-Golgi soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE), modulates beta-amyloid precursor protein processing in neuronal cells. We recently showed that changes in endogenous Syntaxin-5 protein expression occur under stress induction. Syntaxin-5 was upregulated by endoplasmic reticulum stress but was degraded by Caspase-3 during apoptosis in neuronal cells. In addition, we showed that sustained endoplasmic reticulum stress promotes Caspase-3-dependent apoptosis during the later phase of the endoplasmic reticulum stress response in NG108-15 cells. In this study, to elucidate the consequences of secretory pathway dysfunction in beta-amyloid precursor protein processing that lead to neuronal cell death, we examined the effect of various stresses on endoplasmic reticulum-Golgi SNARE expression and beta-amyloid precursor protein processing. By using compounds to disrupt Golgi function, we show that Golgi stress promotes upregulation of the endoplasmic reticulum-Golgi SNARE Syntaxin-5, and prolonged stress causes Caspase-3-dependent apoptosis. Golgi stress induced intracellular beta-amyloid precursor protein accumulation and a concomitant decrease in total amyloid-beta production. We also examined the protective effect of the chemical chaperone 4-phenylbutylate on changes in amyloid-beta production and the activation of Caspase-3 induced by endoplasmic reticulum and Golgi stress. The compound alleviated the increase in the amyloid-beta 1-42/amyloid-beta 1-40 ratio induced by endoplasmic reticulum and Golgi stress. Furthermore, 4-phenylbutylate could rescue Caspase-3-dependent apoptosis induced by prolonged organelle stress. These results suggest that organelle stress originating from the endoplasmic reticulum and Golgi has a substantial impact on the amyloidogenic processing of beta-amyloid precursor protein and Caspase-3-dependent apoptosis, leading to neuronal cell death.

Inducing Cortical Plasticity to Manipulate and Consolidate Subjective Time Interval Production

OBJECTIVES

Time awareness may change depending on the mental state or disease conditions, although each individual perceives his/her own sense of time as stable and accurate. Nevertheless, the processes that consolidate altered duration production remain unclear. The present study aimed to manipulate the subjective duration production via memory consolidation through the modulation of neural plasticity.

MATERIALS AND METHODS

We first performed false feedback training of duration or length production and examined the period required for natural recovery from the altered production. Next, persistent neural plasticity was promoted by quadripulse transcranial magnetic stimulation (QPS) over the right dorsolateral prefrontal cortex (DLPFC), temporoparietal junction (TPJ), and primary motor cortex (M1). We conducted the same feedback training in the individual and studied how the time course of false learning changed.

RESULTS

We observed that altered duration production after false feedback returned to baseline within two hours. Next, immediate exposure to false feedback during neural plasticity enhancement revealed that in individuals who received QPS over the right DLPFC, but not over TPJ or M1, false duration production was maintained for four hours; furthermore, the efficacy persisted for at least one week.

CONCLUSION

These findings suggest that, while learned altered duration production decays over several hours, QPS over the right DLPFC enables the consolidation of newly learned duration production.

On-Reading (Chinese-Style Pronunciation) Predominance Over Kun-Reading (Native Japanese Pronunciation) in Japanese Semantic Dementia

Japanese kanji (morphograms) have two ways of reading: on-reading (Chinese-style pronunciation) and kun-reading (native Japanese pronunciation). It is known that some Japanese patients with semantic dementia read kanji with on-reading but not with kun-reading. To characterize further reading impairments of patients with semantic dementia, we analyzed data from a total of 9 patients who underwent reading and writing tests of kanji and kana (Japanese phonetic writing) and on-kun reading tests containing two-character kanji words with on-on reading, kun-kun reading, and specific (so-called Jukujikun or irregular kun) reading. The results showed that on-reading preceding (pronouncing first with on-reading) and kun-reading deletion (inability to recall kun-reading) were observed in nearly all patients. In the on-kun reading test, on-reading (57.6% correct), kun-reading (46.6% correct), and specific-reading (30.0% correct) were more preserved in this decreasing order (phonology-to-semantics gradient), although on-reading and kun-reading did not significantly differ in performance, according to a more rigorous analysis after adjusting for word frequency (and familiarity). Furthermore, on-substitution (changing to on-reading) errors in kun-reading words (27.0%) were more frequent than kun-substitution (changing to kun-reading) errors in on-reading words (4.0%). These results suggest that kun-reading is more predominantly disturbed than on-reading, probably because kun-reading and specific-reading are closely associated with the meaning of words.

Time Distortion in Parkinsonism

Although animal studies and studies on Parkinson’s disease (PD) suggest that dopamine deficiency slows the pace of the internal clock, which is corrected by dopaminergic medication, timing deficits in parkinsonism remain to be characterized with diverse findings. Here we studied patients with PD and progressive supranuclear palsy (PSP), 3–4 h after drug intake, and normal age-matched subjects. We contrasted perceptual (temporal bisection, duration comparison) and motor timing tasks (time production/reproduction) in supra- and sub-second time domains, and automatic versus cognitive/short-term memory–related tasks. Subjects were allowed to count during supra-second production and reproduction tasks. In the time production task, linearly correlating the produced time with the instructed time showed that the “subjective sense” of 1 s is slightly longer in PD and shorter in PSP than in normals. This was superposed on a prominent trend of underestimation of longer (supra-second) durations, common to all groups, suggesting that the pace of the internal clock changed from fast to slow as time went by. In the time reproduction task, PD and, more prominently, PSP patients over-reproduced shorter durations and under-reproduced longer durations at extremes of the time range studied, with intermediate durations reproduced veridically, with a shallower slope of linear correlation between the presented and produced time. In the duration comparison task, PD patients overestimated the second presented duration relative to the first with shorter but not longer standard durations. In the bisection task, PD and PSP patients estimated the bisection point (BP50) between the two supra-second but not sub-second standards to be longer than normal subjects. Thus, perceptual timing tasks showed changes in opposite directions to motor timing tasks: underestimating shorter durations and overestimating longer durations. In PD, correlation of the mini-mental state examination score with supra-second BP50 and the slope of linear correlation in the reproduction task suggested involvement of short-term memory in these tasks. Dopamine deficiency didn’t correlate significantly with timing performances, suggesting that the slowed clock hypothesis cannot explain the entire results. Timing performance in PD may be determined by complex interactions among time scales on the motor and sensory sides, and by their distortion in memory.

Stopwatch training improves cognitive functions in patients with Parkinson's disease

Parkinson's disease (PD) impairs various cognitive functions, including time perception. Dysfunctional time perception in PD is poorly understood, and no study has investigated the rehabilitation of time perception in patients with PD. We aimed to induce the recovery of time perception in PD patients and investigated the potential relationship between recovery and cognitive functions/domains other than time perception. Sixty patients with PD (27 females) and 20 healthy controls (10 females) were recruited. The participants underwent a feedback training protocol for 4 weeks to improve the accuracy of subjective spatial distance or time duration using a ruler or stopwatch, respectively. They participated in three tests at weekly intervals, each comprising 10 types of cognitive tasks and assessments. After duration feedback training for 1 month, performance on the Go/No-go task, Stroop task, and impulsivity assessment improved in patients with PD, while no effect was observed after distance feedback training. Additionally, the effect of training on duration production correlated with extended reaction time and improved accuracy in the Go/No-go and Stroop tasks. These findings suggest that time perception is functionally linked to inhibitory systems. If the feedback training protocol can modulate and maintain time perception, it may improve various cognitive/psychiatric functions in patients with PD. It may also be useful in the treatment of diseases other than PD that cause dysfunctions in temporal processing.

Premature saccades: A detailed physiological analysis

OBJECTIVE

Premature saccades (PSs) are those made with latencies too short for the direction and amplitude to be specifically programmed. We sought to determine the minimum latency needed to establish accurate direction and amplitude, and observed what occurs when saccades are launched before this minimum latency.

METHODS

In Experiment 1, 249 normal subjects performed the gap saccade task with horizontal targets. In Experiment 2, 28 normal subjects performed the gap saccade task with the targets placed in eight directions. In Experiment 3, 38 normal subjects, 49 patients with Parkinson's disease (PD), and 10 patients with spinocerebellar degeneration (SCD) performed the gap saccade task with horizontal targets.

RESULTS

In Experiment 1, it took 100 ms to accurately establish saccade amplitudes and directions. In Experiment 2, however, the latencies needed for accurate amplitude and direction establishment were both approximately 150 ms. In Experiment 3, the frequencies of PSs in patients with PD and SCD were lower than those of normal subjects.

CONCLUSIONS

The saccade amplitudes and directions are determined simultaneously, 100-150 ms after target presentation. PSs may result from prediction of the oncoming target direction or latent saccade activities in the superior colliculus.

SIGNIFICANCE

Saccade direction and amplitude are determined simultaneously.

Syntaxin 1B regulates synaptic GABA release and extracellular GABA concentration, and is associated with temperature-dependent seizures

De novo heterozygous mutations in the STX1B gene, encoding syntaxin 1B, cause a familial, fever-associated epilepsy syndrome. Syntaxin 1B is an essential component of the pre-synaptic neurotransmitter release machinery as a soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein that regulates the exocytosis of synaptic vesicles. It is also involved in regulating the functions of the SLC6 family of neurotransmitter transporters that reuptake neurotransmitters, including inhibitory neurotransmitters, such as γ-aminobutyric acid (GABA) and glycine. The purpose of the present study was to elucidate the molecular mechanisms underlying the development of febrile seizures by examining the effects of syntaxin 1B haploinsufficiency on inhibitory synaptic transmission during hyperthermia in a mouse model. Stx1b gene heterozygous knockout (Stx1b^+/- ) mice showed increased susceptibility to febrile seizures and drug-induced seizures. In cultured hippocampal neurons, we examined the temperature-dependent properties of neurotransmitter release and reuptake by GABA transporter-1 (GAT-1) at GABAergic neurons using whole-cell patch-clamp recordings. The rate of spontaneous quantal GABA release was reduced in Stx1b^+/- mice. The hyperthermic temperature increased the tonic GABA_A current in wild-type (WT) synapses, but not in Stx1b^+/- synapses. In WT neurons, recurrent bursting activities were reduced in a GABA-dependent manner at hyperthermic temperature; however, this was abolished in Stx1b^+/- neurons. The blockade of GAT-1 increased the tonic GABA_A current and suppressed recurrent bursting activities in Stx1b^+/- neurons at the hyperthermic temperature. These data suggest that functional abnormalities associated with GABA release and reuptake in the pre-synaptic terminals of GABAergic neurons may increase the excitability of the neural circuit with hyperthermia.

Clinical efficacy of haematopoietic stem cell transplantation for adult adrenoleukodystrophy

Accumulated experience supports the efficacy of allogenic haematopoietic stem cell transplantation in arresting the progression of childhood-onset cerebral form of adrenoleukodystrophy in early stages. For adulthood-onset cerebral form of adrenoleukodystrophy, however, there have been only a few reports on haematopoietic stem cell transplantation and the clinical efficacy and safety of that for adulthood-onset cerebral form of adrenoleukodystrophy remain to be established. To evaluate the clinical efficacy and safety of haematopoietic stem cell transplantation, we conducted haematopoietic stem cell transplantation on 12 patients with adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy in a single-institution-based prospective study. Through careful prospective follow-up of 45 male adrenoleukodystrophy patients, we aimed to enrol patients with adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy at early stages. Indications for haematopoietic stem cell transplantation included cerebral form of adrenoleukodystrophy or cerebello-brainstem form of adrenoleukodystrophy with Loes scores up to 13, the presence of progressively enlarging white matter lesions and/or lesions with gadolinium enhancement on brain MRI. Clinical outcomes of haematopoietic stem cell transplantation were evaluated by the survival rate as well as by serial evaluation of clinical rating scale scores and neurological and MRI findings. Clinical courses of eight patients who did not undergo haematopoietic stem cell transplantation were also evaluated for comparison of the survival rate. All the patients who underwent haematopoietic stem cell transplantation survived to date with a median follow-up period of 28.6 months (4.2–125.3 months) without fatality. Neurological findings attributable to cerebral/cerebellar/brainstem lesions became stable or partially improved in all the patients. Gadolinium-enhanced brain lesions disappeared or became obscure within 3.5 months and the white matter lesions of MRI became stable or small. The median Loes scores before haematopoietic stem cell transplantation and at the last follow-up visit were 6.0 and 5.25, respectively. Of the eight patients who did not undergo haematopoietic stem cell transplantation, six patients died 69.1 months (median period; range 16.0–104.1 months) after the onset of the cerebral/cerebellar/brainstem lesions, confirming that the survival probability was significantly higher in patients with haematopoietic stem cell transplantation compared with that in patients without haematopoietic stem cell transplantation (P = 0.0089). The present study showed that haematopoietic stem cell transplantation was conducted safely and arrested the inflammatory demyelination in all the patients with adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy when haematopoietic stem cell transplantation was conducted in the early stages. Further studies are warranted to optimize the procedures of haematopoietic stem cell transplantation for adolescent-/adult-onset cerebral form/cerebello-brainstem form of adrenoleukodystrophy.

Rituximab improves not only back stiffness but also "stiff eyes" in stiff person syndrome: Implications for immune-mediated treatment

OBJECTIVE

Stiff person syndrome (SPS) is usually characterized by truncal muscle rigidity and episodic painful spasms, but it sometimes appears with ocular symptoms called "stiff eyes". We recorded saccade movements in an SPS patient manifesting with "stiff eyes" conditions with slow saccade velocity and evaluated the effect of immunotherapy including rituximab on saccade parameters.

METHODS

We repeatedly conducted saccade eye recordings using video-based eye tracking system on a 42-year-old male SPS patient with slow saccade. The velocity and onset latency of visual guided saccades (VGS) were measured at each recording. Because VGS velocity is affected by saccade amplitude, estimated peak velocity (Vmax) was also calculated by taking the relationship between the velocity and the amplitude of saccade into account.

RESULTS

The mean VGS velocity improved significantly after two courses of rituximab administration compared with its lowest value. The estimated Vmax decreased as the clinical manifestations worsened, but it increased after rituximab administration. Other neurological symptoms in this patient such as muscle rigidity and gait instability also improved after the treatment.

CONCLUSION

Slow saccade in a "stiff eyes" patient improved after rituximab administration. Our study also indicated that the saccade eye recording is useful for evaluating the clinical condition of SPS when it is complicated with ocular symptoms.

Effects of L-DOPA on quadripulse magnetic stimulation-induced long-term potentiation in older adults

Reduced cortical plasticity has been previously reported in older adult as compared with young adults. However, the effects of dopamine on this plasticity reduction remain unknown. Here, we assessed the effects of high-dose (200 mg) and medium-dose (100 mg) L-3,4-dihydroxyphenylalanine (L-DOPA) intake on the long-term potentiation (LTP)-like effect induced by quadripulse magnetic stimulation (QPS) in older adults (aged ∼65 years). The subjects were 32 (200 mg) and 20 (100 mg) healthy older adult volunteers. This study was designed as a double-blind, crossover and placebo-controlled trial on one dose of L-dopa. Two hours after taking L-DOPA or placebo-drug, QPS was applied over the motor cortex. Motor evoked potentials were recorded to evaluate the motor cortical excitability changes. We found that both doses of L-DOPA enhanced LTP after QPS in older adults as one group. We classified subjects into QPS responders and QPS nonresponders. Both L-DOPA doses produced significant LTP enhancement in QPS nonresponders, whereas either of doses did not produce significant LTP enhancement in QPS responders. Collectively, our findings suggest that the neural plasticity reductions observed in older adults could be partly improved by dopamine.

Contraction of distance and duration production in autism spectrum disorder

Autism spectrum disorder (ASD) presents certain hallmark features associated with cognitive and social functions, however, the ability to estimate self-generated distance and duration in individuals with ASD are unclear. We compared the performance of 20 ASD individuals with 20 typical developments (TDs) with respect to two tasks: (1) the drawing of a line of a specified distance (10 or 20 cm) and (2) waiting for a specified time (10 or 20 s). We observed that both the line distances and waiting times were substantially shorter in the ASD group than in the TD group. Furthermore, a trait of "attention to detail," as measured by the Autism-Spectrum Quotient, correlated with some distance and duration productions observed in individuals with ASD. We suggest that attentional functions are related to the contraction of distance and duration in ASD.

Supplementary motor area plays a causal role in automatic inhibition of motor responses

BACKGROUND

The masked-priming paradigm is used to test unconscious inhibitory processes of the brain. A tendency towards responses that are incompatible with the prime, designated as negative compatibility effect (NCE), emerges when the perception of a priming visual stimulus is "masked" afterwards. This effect presumably stems from a subliminal inhibitory process against the masked-prime. Prior lesions as well as activation studies suggest a key role of SMA in this effect.

OBJECTIVE

This study was conducted to elucidate a causal role of SMA in the subliminal response inhibition represented by the NCE.

METHODS

Using a repeated-measures pre-post design with a group of healthy people, physiological measures (resting and active motor thresholds and motor evoked potential (MEP) amplitude) and behavioral ones (choice reaction time (CRT), positive compatibility effect (PCE) and NCE) were obtained before and after three quadripulse stimulation (QPS), namely sham, M1-QPS, and SMA-QPS, on different days. CRT and PCE served as indices for different aspects of motor execution.

RESULTS

Motor thresholds were not altered after any QPS, although the M1-QPS increased MEP amplitude. Neither CRT nor PCE was altered significantly after QPS protocols. NCE was abolished after the SMA-QPS.

CONCLUSIONS

Abolished NCE after the SMA-QPS in the absence of MEP changes suggests that (1) SMA plays a cardinal role in the NCE, and (2) the network involved in NCE is different from that of MEP generation.

Impaired cognitive modification for estimating time duration in Parkinson's disease

Parkinson's disease (PD) is associated with various cognitive impairments. However, the nature of cognitive modification in patients with PD remains to be elucidated. In the present study, we examined whether patients with PD could correct and maintain subjective time duration and line length estimation. After training sessions, in which participants repeatedly memorized either a duration or a length, we compared a learning performance in 20 PD patients with 20 healthy controls. In the case of duration in the PD patients, the learned durations immediately returned to baseline of pre-training within a few minutes. However, the patients’ ability to learn length estimation remained unimpaired. In contrast, healthy controls were able to retain the learned duration and length estimations. Time compression in PD's internal clock may become entrained to their altered duration estimation even after learning of accurate time duration. These deficits may be associated with disrupting cognitive modification in PD.

Optic neuropathy and decorticate-like posture as presenting symptoms of Bickerstaff's brainstem encephalitis: A case report and literature review

A 72-year-old woman with a 10-day history of bilateral visual impairment after respiratory tract infection showed decorticate-like posture and progressive deterioration of consciousness leading to coma. Ophthalmoplegia was also noted and anti-GQ1b antibodies were positive, consistent with Bickerstaff's brainstem encephalitis. After intravenous immunoglobulin and steroid pulse therapy, her consciousness gradually improved. However, severe visual impairment at the level of hand motion was noticed, which gradually normalized after second steroid pulse therapy. Atypical findings including optic neuropathy and decorticate-like posture can be seen in patients with Bickerstaff's brainstem encephalitis, and early diagnosis is essential for adequate management.

Modulation of motor learning by a paired associative stimulation protocol inducing LTD-like effects

BACKGROUND

Paired associative stimulation (PAS) induces long-term potentiation (LTP)-like effects when interstimulus intervals (ISIs) between electrical peripheral nerve stimulation and transcranial magnetic stimulation (TMS) to M1 are approximately 21-25 ms (PAS_LTP). It was previously reported that two forms of motor learning (i.e., mode-free and model-based learning) can be differentially modulated by PAS_LTP depending on the different synaptic inputs to corticospinal neurons (CSNs), which relate to posterior-to-anterior (PA) or anterior-to-posterior (AP) currents induced by TMS (PA or AP inputs, respectively). However, the effects of long-term depression (LTD)-inducing PAS with an ISI of approximately 10 ms (PAS_LTD) on motor learning and its dependency on current direction have not yet been tested.

OBJECTIVE

To investigate whether, and how, PAS_LTD affects distinct types of motor learning.

METHODS

Eighteen healthy volunteers participated. We adopted the standard PAS using suprathreshold TMS with the target muscle relaxed, as well as subthreshold PAS during voluntary contraction, which was suggested to selectively recruit PA or AP inputs depending on the orientation of the TMS coil. We examined the effects of suprathreshold and subthreshold PAS_LTD on the performance of model-free and model-based learning, as well as the corticospinal excitability, indexed as the amplitudes of motor evoked potentials (MEPs).

RESULTS

PAS_LTD inhibited model-free learning and MEPs only when subthreshold AP currents were applied. The PAS_LTD protocols tested here showed no effects on model-based learning.

CONCLUSIONS

PAS_LTD affected model-free learning, presumably by modulating CSN excitability changes, rather than PA inputs, which are thought to be related to model-free learning.

Does the Clock Tick Slower or Faster in Parkinson's Disease? - Insights Gained From the Synchronized Tapping Task

The rhythm of the internal clock is considered to be determined by the basal ganglia, with some studies suggesting slower internal clock in Parkinson's disease (PD). However, patients may also show motor hastening when they walk (festination) or are engaged in repetitive tapping, indicating faster ticking of the internal clock. Is the internal clock slower or faster in PD? The purpose of this study was to answer this question, i.e., how fast and slow a rhythm they can synchronize with, especially with reference to the limit of sensorimotor synchronization or temporal integration, representing the threshold of slower pace they can entrain into their motor actions, which is known to lie between 2 and 3 s in normal subjects but not yet studied in PD. We employed a synchronized tapping task that required subjects to tap the key in synchrony with repetitive tones at fixed interstimulus intervals (ISI) between 200 and 4800 ms. Twenty normal subjects and sixteen PD patients were enrolled, who were classified into early and advanced PD groups by UPDRS-III (early: 15 or less, advanced: more than 15). The ISI at which the response changes from synchronizing with the tones to lagging behind them was considered to be the limit of temporal integration. Early PD patients responded ahead of the tones (negative asynchrony), which became more apparent with repeated tapping. This suggested "faster" ticking clock even in the presence of the pacing tones. In normal subjects, the limit of temporal integration was around 2-3 s: below this, subjects could synchronize with the tones, while above it they had difficulty in synchronization. In early PD patients, the limit of temporal integration was significantly longer than in normal subjects, pointing to their enhanced ability to synchronize also with slower paces of tones, but advanced PD patients had significantly shortened limits, suggesting that advanced patients lost this ability. In conclusion, the limit of temporal integration is initially longer but gets shorter as the disease progresses. It can be explained by the hastening of the internal clock at the earlier stages of PD, followed by the loss of temporal integration.

Recording Horizontal Saccade Performances Accurately in Neurological Patients Using Electro-oculogram

Electro-oculogram (EOG) has been widely used for clinical eye movement recording, especially horizontal saccades, although the video-oculography (VOG) has largely taken the place of it nowadays due to its higher spatial accuracy. However, there are situations in which EOG has clear advantages over VOG, e.g., subjects with narrow eye clefts or having cataract lenses, and patients with movement disorders. The present article shows that if properly implemented, EOG can achieve an accuracy almost as good as VOG with substantial stability for recording, while circumventing problems associated with VOG recording. The present paper describes a practical method for recording horizontal saccades using oculomotor paradigms with high accuracy and stability by EOG in neurological patients. The necessary measures are to use an Ag-AgCl electrode with a wide plastic fringe capable of reducing noise, and to wait for sufficient light adaptation to occur. This waiting period also helps to lower the impedance between the electrodes and the skin, thereby ensuring stable signal recorded as time goes by. Furthermore, re-calibration is performed as needed during the task performance. Using this method, the experimenter can avoid drifts of signals, as well as contamination of artifacts or noise from the electromyogram and electroencephalogram, and can collect sufficient data for clinical evaluation of saccades. Thus when implemented, EOG can still be a method of high practicability that can be widely applied to neurological patients, but may be effective also for studies in normal subjects.

A significant correlation between cauda equina conduction time and cerebrospinal fluid protein in chronic inflammatory demyelinating polyradiculoneuropathy

We investigated the relationship between the involvement of the cauda equina in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and the increment of cerebrospinal fluid (CSF) protein. We measured cauda equina conduction time (CECT) in 14 CIDP patients using magnetic stimulation with a MATS coil. Statistical analysis revealed that CECT and CSF protein had a significant positive linear correlation. Conduction time of the peripheral nerve trunk, in contrast, had no significant linear correlation with CSF protein. We revealed that the involvement of the cauda equina and increment of CSF protein are closely related. In CIDP cases with elevated CSF protein, spinal nerves including the cauda equina are very likely involved.