Central Information Processing Research Articles

Learning and memory in Rhodnius prolixus: habituation and aversive operant conditioning of the proboscis extension response

It has been largely accepted that the cognitive abilities of disease vector insects may have drastic consequences on parasite transmission. However, despite the research effort that has been invested in the study of learning and memory in haematophagous insects, hitherto few conclusive results have been obtained. Adapting procedures largely validated in Drosophila, honeybees and butterflies, we demonstrate here that the proboscis extension response (PER) of the haematophagous insect Rhodnius prolixus can be modulated by non-associative (habituation) and associative (aversive conditioning) learning forms. Thermal stimuli were used as both unconditional stimulus (appetitive temperatures) and negative reinforcement (thermal shock). In the first part of this work, the PER was habituated and dishabituated to thermal stimuli, demonstrating the true central processing of information and discarding motor fatigue or sensory adaptation. Habituation was revealed to be modulated by the spatial context. In the second part, bugs that were submitted to aversive operant conditioning stopped responding with PER to thermal stimulation more quickly than by habituation. They were able to use their training experience when tested up to 72 h later. Our work constitutes the first demonstration of PER habituation and conditioning in a blood-sucking insect and provides reproducible experimental tools for the study of the mechanisms underlying learning and memory in disease vectors.

Evaluation of Age-Related Hearing Loss

Age-related hearing loss (presbycusis) is characterized by an increased hearing threshold and poor speech understanding in a noisy environment, slowed central processing of acoustic information, and impaired localization of sound sources. Presbycusis seriously affects the older people's quality of life. Particularly, hearing loss in the elderly contributes to social isolation, depression, and loss of self-esteem. Current amplification methods related to auditory rehabilitation can provide improved communication ability to users. But, simple auditory rehabilitation is ineffective in managing the central auditory processing disorder and the psychosocial problem of presbycusis. The evaluation of central auditory processing disorder and psychosocial disorder in presbycusis should not be overlooked while providing auditory rehabilitation.

Pain and chronic pancreatitis: A complex interplay of multiple mechanisms

Despite multiple theories on the pathogenesis of pain in chronic pancreatitis, no uniform and consistently successful treatment strategy exists and abdominal pain still remains the dominating symptom for most patients and a major challenge for clinicians. Traditional theories focussed on a mechanical cause of pain related to anatomical changes and evidence of increased ductal and interstitial pressures. These observations form the basis for surgical and endoscopic drainage procedures, but the outcome is variable and often unsatisfactory. This underscores the fact that other factors must contribute to pathogenesis of pain, and has shifted the focus towards a more complex neurobiological understanding of pain generation. Amongst other explanations for pain, experimental and human studies have provided evidence that pain perception at the peripheral level and central pain processing of the nociceptive information is altered in patients with chronic pancreatitis, and resembles that seen in neuropathic and chronic pain disorders. However, pain due to e.g., complications to the disease and adverse effects to treatment must not be overlooked as an additional source of pain. This review outlines the current theories on pain generation in chronic pancreatitis which is crucial in order to understand the complexity and limitations of current therapeutic approaches. Furthermore, it may also serve as an inspiration for further research and development of methods that can evaluate the relative contribution and interplay of different pain mechanisms in the individual patients, before they are subjected to more or less empirical treatment.

Corneal afferents differentially target thalamic- and parabrachial-projecting neurons in spinal trigeminal nucleus caudalis

Dorsal horn neurons send ascending projections to both thalamic nuclei and parabrachial nuclei; these pathways are thought to be critical pathways for central processing of nociceptive information. Afferents from the corneal surface of the eye mediate nociception from this tissue which is susceptible to clinically important pain syndromes. This study examined corneal afferents to the trigeminal dorsal horn and compared inputs to thalamic- and parabrachial-projecting neurons. We used anterograde tracing with cholera toxin B subunit to identify corneal afferent projections to trigeminal dorsal horn, and the retrograde tracer FluoroGold to identify projection neurons. Studies were conducted in adult male Sprague-Dawley rats. Our analysis was conducted at two distinct levels of the trigeminal nucleus caudalis (Vc) which receive corneal afferent projections. We found that corneal afferents project more densely to the rostral pole of Vc than the caudal pole. We also quantified the number of thalamic- and parabrachial-projecting neurons in the regions of Vc that receive corneal afferents. Corneal afferent inputs to both groups of projection neurons were also more abundant in the rostral pole of Vc. Finally, by comparing the frequency of corneal afferent appositions to thalamic- versus parabrachial-projecting neurons, we found that corneal afferents preferentially target parabrachial-projecting neurons in trigeminal dorsal horn. These results suggest that nociceptive pain from the cornea may be primarily mediated by a non-thalamic ascending pathway.

Cognitive effects of interictal epileptiform discharges in children

Frequent interictal epileptiform discharges (IEDs) may have effects on cognition. We analysed a group of 182 children with different epilepsy syndromes, all of whom had IEDs that did not result in observed seizures, with 24-h ambulatory EEG and cognitive tests. The IED index was estimated, in wakefulness and in sleep, as percentage of time in five categories (0%, <1%, 1–10%, ≥10–50% and ≥50%). IEDs were defined as spikes or spike–wave complexes, isolated or occurring serially (in runs) without evident clinical signs of a seizure. The IED categories were correlated to cognitive test results and epilepsy characteristics. The group of patients with diurnal IEDs in ≥10% of the EEG record showed impaired central information processing speed, short-term verbal memory and visual-motor integration. This effect was seen independently from other EEG-related and epilepsy-related characteristics, and independently from epilepsy syndrome diagnosis. The impact of the nocturnal IEDs was of less importance; only contributing partially to the slowing of central information processing speed. We conclude that frequent IEDs (in more than 10% of the record) in the awake EEG can impair cognitive performance in children. Whether children with a high diurnal spike frequency and low seizure frequency can benefit from antiepileptic treatment should be examined in controlled trials.

The cognitive effects of interictal epileptiform EEG discharges and short nonconvulsive epileptic seizures

Educational difficulties or even severe cognitive deterioration is seen in many childhood epilepsy syndromes. Many of those cognitive deficits are related directly to the brain disorder underlying the epilepsy syndrome. However, in other types of epilepsy, the epileptic seizures and/or epileptiform activity can be the dominant factor. This is especially unknown for the more "subtle" short nonconvulsive seizure types. For this reason, we analyzed a new cohort of children. A cross-sectional study of 188 children with epilepsy. Electroencephalography (EEG)-video recordings and cognitive testing were performed simultaneously. The results of children with short nonconvulsive seizures during a 2-h testing session were compared with all children with epilepsy without seizures during the 2-h cognitive testing session and with controls without epilepsy. In a second analysis the cognitive effects of frequency of epileptiform EEG discharges were analyzed. The cognitive effects of short nonconvulsive seizures were large, ranging from 0.5 to 1 standard deviation and concerned global cognitive function, speed of central information processing, and memory function. In children without seizures during cognitive testing, the occurrence of frequent epileptiform discharges showed more subtle effects. These effects were independent from the occurrence of short nonconvulsive seizures. We concluded that although the effect is less pronounced in number of areas involved and magnitude, the type of association between frequent epileptiform activity (>1% of the time) and cognitive function in children with epilepsy is comparable to the association between short nonconvulsive seizures and cognitive function.

Opioid mechanisms that mediate the palatability of and appetite for salt in sodium replete and deficient states

Sodium deficiency reliably produces a robust intake of saline in rats, which is associated with an increased preference for sodium solutions at hypertonic concentrations that would normally be avoided. The mechanisms underlying the shift to an increased preference for sodium in the deficient state are not well understood. The current experiments examined the role of opioids on changes of behavioral responses that are modified as a function of body sodium status by studying the intake of 0.3M saline in a free access drinking test and by characterizing the changes in orofacial-related behaviors in response to intra-orally delivered 0.3M NaCl. In intake tests, systemic treatment with morphine and naltrexone respectively, enhanced and attenuated intake of 0.3M saline in sodium depleted rats. In taste reactivity tests systemic treatment with morphine significantly decreased negative responses to 0.3M saline infusions in both sodium replete and sodium depleted rats. Systemically administered naltrexone significantly decreased positive hedonic responses to 0.3M saline infusions only in sodium depleted rats. These results indicate that peripheral administration of opioid agonists and antagonists alter both hypertonic saline ingestion in a free access situation and taste reactivity responses to hypertonic saline under sodium replete and deplete conditions. The results indicate that endogenous opioids alter the processing of central information to affect hedonic mechanisms that influence behaviors related to sodium consumption and palatability.

Segregation of visual inputs from different regions of the compound eye in two parallel pathways through the anterior optic tubercle of the bumblebee (Bombus ignitus)

AbstractVisually guided behaviors require the brain to extract features of the visual world and to integrate them in a context‐specific manner. Hymenopteran insects have been prime models for ethological research into visual behaviors for decades but knowledge about the underlying central processing is very limited. This is particularly the case for sky‐compass navigation. To learn more about central processing of visual information in general and specifically to reveal a possible polarization vision pathway in the bee brain, we used tracer injections to investigate the pathways through the anterior optic tubercle, a prominent output target of the insect optic lobe, in the bumblebee Bombus ignitus. The anterior optic tubercle of the bumblebee is a small neuropil of 200 μm width and is located dorsolateral to the antennal lobe at the anterior surface of the brain. It is divided into a larger upper and a smaller lower subunit, both of which receive input from the optic lobe and connect to the lateral accessory lobe, and the contralateral tubercle, via two parallel pathways. The lower subunit receives input from the dorsal rim area (DRA) of the compound eye. The bumblebee DRA shares structural similarities with polarization‐sensitive DRAs of other insects and looks similar to that of honeybees. We identified several neurons within this pathway that could be homologous to identified polarization‐sensitive neurons in the locust brain. We therefore conclude that the pathway through the lower subunit of the anterior optic tubercle could carry polarization information from the periphery to the central brain. J. Comp. Neurol. 520:212–229, 2012. © 2011 Wiley Periodicals, Inc.

Segregation of visual inputs from different regions of the compound eye in two parallel pathways through the anterior optic tubercle of the bumblebee (Bombus ignitus)

Visually guided behaviors require the brain to extract features of the visual world and to integrate them in a context-specific manner. Hymenopteran insects have been prime models for ethological research into visual behaviors for decades but knowledge about the underlying central processing is very limited. This is particularly the case for sky-compass navigation. To learn more about central processing of visual information in general and specifically to reveal a possible polarization vision pathway in the bee brain, we used tracer injections to investigate the pathways through the anterior optic tubercle, a prominent output target of the insect optic lobe, in the bumblebee Bombus ignitus. The anterior optic tubercle of the bumblebee is a small neuropil of 200 μm width and is located dorsolateral to the antennal lobe at the anterior surface of the brain. It is divided into a larger upper and a smaller lower subunit, both of which receive input from the optic lobe and connect to the lateral accessory lobe, and the contralateral tubercle, via two parallel pathways. The lower subunit receives input from the dorsal rim area (DRA) of the compound eye. The bumblebee DRA shares structural similarities with polarization-sensitive DRAs of other insects and looks similar to that of honeybees. We identified several neurons within this pathway that could be homologous to identified polarization-sensitive neurons in the locust brain. We therefore conclude that the pathway through the lower subunit of the anterior optic tubercle could carry polarization information from the periphery to the central brain.

Dopaminergic mechanisms of target detection — P300 event related potential and striatal dopamine

The P300 is a cortically generated event related potential (ERP) widely used in neurophysiological research since it is related to cognitive functions and central information processing. Intracerebral recordings and functional neuroimaging studies have demonstrated that this potential is generated by various brain regions including frontal, temporal and parietal cortices. Regarding the neurochemical background, clinical and genetic investigations suggest that dopaminergic neurons could be involved in the generation of the P300. However, there is no direct evidence in vivo that P300 amplitudes and latencies are related to dopaminergic parameters. The aim of this study was to further elucidate dopaminergic aspects of the P300 ERP by combining neurophysiological and nuclear medicine assessments in vivo. Patients with a major depressive episode underwent both P300 recordings and dynamic [123I] IBZM SPECT for the evaluation of striatal dopamine D2/D3-receptor availability. There were statistically significant positive correlations of the striatal dopamine D2/D3-receptor status with P300 amplitudes and significant negative correlations with P300 latencies. Using this combined approach, the study presents direct evidence in vivo that the central dopaminergic system might play an important role in the generation of the P300 and that central dopaminergic activity could be involved in the modulation of P300 parameters. This association might be of relevance for the interpretation of P300 studies in psychiatric disorders.

Postural Instability in Early-Stage Idiopathic Scoliosis in Adolescent Girls

Cross-sectional study. To evaluate whether the amplitude of spine deformation in adolescent idiopathic scoliosis (AIS) is an important factor for postural control at disease onset. AIS is related to disorders of postural control with potential involvement of vestibular, proprioceptive, and visual input. So far no assessment of postural control has been done in an AIS population at the onset of spine deformation. Sixty-five female patients with AIS (mean age: 11.4 ± 2.3 years) were clinically and radiologically assessed at the time of diagnosis and evaluated in posturography, including static tests-with and without sensory conflict-and dynamic tests. Two groups were formed according to the mean Cobb angle of the primary curve. The mean Cobb angle was 14.8° ± 5.1°; 35 patients were included in group I with a Cobb angle of 5° to 14°, and 30 patients into group II with a Cobb angle of 15° to 25°. The latter group displayed higher body sways in static tests, characterized by a larger area covered by center of foot pressure in both eyes open and eyes closed conditions, and by higher lateral oscillations in only the eyes closed condition. Group II patients displayed poorer balance control, mainly in visual and somatosensory conflict conditions. Group II patients used fewer anticipatory strategies to stabilize body oscillations than Group I patients, especially in the more challenging sensory conflict and dynamic situations. Poorer postural performance, especially in sensory conflict situations, observed in patients with a Cobb angle greater or equal to 15°, reflect less effective central information processing.

Management of postural sensory conflict and dynamic balance control in late-stage Parkinson's disease

Parkinson's disease (PD) is known to affect postural control, especially in situations needing a change in balance strategy or when a concurrent task is simultaneously performed. However, few studies assessing postural control in patients with PD included homogeneous population in late stage of the disease. Thus, this study aimed to analyse postural control and strategies in a homogeneous population of patients with idiopathic advanced (late-stage) PD, and to determine the contribution of peripheral inputs in simple and more complex postural tasks, such as sensory conflicting and dynamic tasks. Twenty-four subjects with advanced PD (duration: median (M)=11.0 years, interquartile range (IQR)=4.3 years; Unified Parkinson's Disease Rating Scale (UPDRS): M "on-dopa"=13.5, IQR=7.8; UPDRS: M "off-dopa"=48.5, IQR=16.8; Hoehn and Yahr stage IV in all patients) and 48 age-matched healthy controls underwent static (SPT) and dynamic posturographic (DPT) tests and a sensory organization test (SOT). In SPT, patients with PD showed reduced postural control precision with increased oscillations in both anterior-posterior and medial-lateral planes. In SOT, patients with PD displayed reduced postural performances especially in situations in which visual and vestibular cues became predominant to organize balance control, as was the ability to manage balance in situations for which visual or proprioceptive inputs are disrupted. In DPT, postural restabilization strategies were often inefficient to maintain equilibrium resulting in falls. Postural strategies were often precarious, postural regulation involving more hip joint than ankle joint in patients with advanced PD than in controls. Difficulties in managing complex postural situations, such as sensory conflicting and dynamic situations might reflect an inadequate sensory organization suggesting impairment in central information processing.

Ambient GABA-Activated Tonic Inhibition Sharpens Auditory Coincidence Detection via a Depolarizing Shunting Mechanism

Tonic inhibition mediated by extrasynaptic GABA(A) receptors (GABA(A)Rs) has emerged as a novel form of neural inhibition in the CNS. However, little is known about its presence and function in the auditory system. Using whole-cell recordings in brain slices, we identified a tonic current mediated by GABA(A)Rs containing the δ subunit in middle/high-characteristic-frequency neurons of the chicken nucleus laminaris, the first interaural time difference encoder that computes information for sound localization. This tonic conductance was activated by ambient concentrations of GABA released from synaptic vesicles. Furthermore, pharmacological manipulations of the conductance demonstrated its essential role in coincidence detection. Remarkably, this depolarizing tonic conductance was strongly inhibitory primarily because of its shunting effect. These results demonstrate a novel role for tonic inhibition in central auditory information processing.

The neural basis of central proprioceptive processing in older versus younger adults: An important sensory role for right putamen

Our sense of body position and movement independent of vision (i.e., proprioception) relies on muscle spindle feedback and is vital for performing motor acts. In this study, we first sought to elucidate age-related differences in the central processing of proprioceptive information by stimulating foot muscle spindles and by measuring neural activation with functional magnetic resonance imaging. We found that healthy older adults activated a similar, distributed network of primary somatosensory and secondary-associative cortical brain regions as young individuals during the vibration-induced muscle spindle stimulation. A significant decrease in neural activity was also found in a cluster of right putamen voxels for the older age group when compared with the younger age group. Given these differences, we performed two additional analyses within each group that quantified the degree to which age-dependent activity was related to (1) brain structure and (2) a behavioral measure of proprioceptive ability. Using diffusion tensor imaging, older (but not younger) adults with higher mean fractional anisotropy were found to have increased right putamen neural activity. Age-dependent right putamen activity seen during tendon vibration was also correlated with a behavioral test of proprioceptive ability measuring ankle joint position sense in both young and old age groups. Partial correlation tests determined that the relationship between elderly joint position sense and neural activity in right putamen was mediated by brain structure, but not vice versa. These results suggest that structural differences within the right putamen are related to reduced activation in the elderly and potentially serve as biomarker of proprioceptive sensibility in older adults.

Вікові особливості швидкості центральної обробки інформації у осіб з різним рівнем функціональної рухливості нервових процесів

The dynamics of the speed formation of the central information processing (CIP) and its connection with functional mobility of nervous processes (FMNP) was investigated among the persons aged 7-20. The indexes of CIP and FMNP among the children, teenagers and youngsters were found to increase gradually and to reach maximum development at the age of 19-20. Statistically significant differences of the CIP speed were found in all age groups of the investigated persons with different levels of FNMP. The persons with high level of FNMP were characterized with reliably high indexes of CIP compared with subjects with the low level of investigated typological properties of high nervous activity (HNA). The correlation proved the reliable relationships between investigated variables. The general age-related conformities in forming CIP and FMNP were established favoring the genetically determined program for development of these nervous system properties. There is a reason to confirm that the index of CIP speed characterizes individual features of information processing and reflects the typological properties of HNA side by side with FMNP.

Age Characteristics of the Speed of Central Information Processing In Persons with Different Levels of Functional Mobility of Nervous Processes

Age Characteristics of the Speed of Central Information Processing In Persons with Different Levels of Functional Mobility of Nervous Processes

Behavioural treatment programme contributes to normalization of contingent negative variation in children with migraine

Migraine is a disorder of central information processing which may be characterized by increased amplitudes and reduced habituation of evoked and event-related potentials. In this pilot study, special behavioural training of habituation to aversive stimuli (MIPAS-Family = Migraine Patient Seminar for Families) was developed and proven effective in children suffering from migraine without aura. 13 children with migraine participated in the MIPAS-Family programme and 13 other children with migraine were treated with biofeedback. The influence of both treatments on abnormal cortical information processing in migraine was assessed using recordings of the contingent negative variation (CNV), an event-related slow cortical potential. Both MIPAS training and biofeedback caused an equal reduction of migraine frequency and severity. However, MIPAS treatment was associated with a significant increase in iCNV habituation. Changes in the clinical course of migraine correlated positively with normalization of habituation: the greater the reduction in headache frequency, the greater the increase in CNV habituation was. These effects were not observed in the biofeedback group. This study demonstrates that the specific treatment programme which was evolved from knowledge of pathogenetic mechanisms of migraine influences central information processing and leads to a clinical effect.

Feeling good: on the role of C fiber mediated touch in interoception

The human skin is innervated by a network of thin, slow-conducting afferent (C and Aδ) fibers, transmitting a diverse range of information. Classically, these fibers are described as thermo-, noci- or chemoreceptive, whereas mechanoreception is attributed exclusively to thick, fast-conducting (Aβ) afferents. A growing body of evidence, however, supports the notion that C tactile afferents comprise a second anatomically and functionally distinct system signaling touch in humans. This review discusses established as well as recent findings which highlight fundamental differences in peripheral and central information coding and processing between Aβ and C mechanoreception. We conclude that from the skin through the brain, C touch shares more characteristics with interoceptive modalities (e.g. pain, temperature, and itch) than exteroceptive Aβ touch, vision or hearing. In this light, we discuss the motivational-affective role of C touch as an integral part of a thin-fiber afferent homeostatic network for the maintenance of physical and social well-being.

Effects of trifluoromethylphenylpiperazine (TFMPP) on interhemispheric communication

'Party Pills' containing trifluoromethylphenylpiperazine (TFMPP) and benzylpiperazine are legally available in many countries and marketed as safe alternatives to other illicit substances such as methamphetamine and methylenedioxymethamphetamine (or Ecstasy). They have gained huge popularity around the world, especially amongst young adults. However, there is no information currently available describing the acute neurophysiological effects of these psychoactive drugs in humans. The purpose of this study is to investigate the effects of TFMPP on central information processing speed in humans. A randomised, double blind, placebo-controlled study using electroencephalography (EEG) was carried out to investigate the effects of TFMPP on interhemispheric transfer time (IHTT). Healthy, right-handed males (age: 25 ± 5.6 years) were given placebo (n = 15) or TFMPP (0.94 mg/kg, oral, n = 15) and tested both pre- and 2 h post-drug administration. High-density EEG recordings (128 channels which were re-referenced using an average reference to make 129 electrodes) were used to record event-related potentials. The N160 component was defined as the biggest negative peak in the range between 140 and 220 ms after the event. The IHHTs were analysed by deducting the N160 latency obtained in the contralateral hemisphere from the N160 latency obtained in the hemisphere ipsilateral to stimulus signal. Statistical analysis using a split-plot design analysis of variance revealed that TFMPP significantly reduced the IHTT but did not affect reaction time. No statistically significant changes were observed in the placebo group. This study is the first to report the neurophysiological effects of TFMPP in humans and suggests that TFMPP may affect transmitter systems involved in speeding of interhemispheric communication in the male brain.

Olfactory system

The olfactory system has several unique features in terms of mechanisms of sensory transduction, relay, and central processing of information and provides a typical example of functional plasticity.1–5 Olfactory deficits are frequently found in neurodegenerative disorders, particularly Parkinson disease (PD) and Alzheimer disease (AD). The neuropathologic substrate of olfactory dysfunction in neurodegenerative disorders is incompletely elucidated and likely reflects degenerative changes at multiple levels of the olfactory system, including the olfactory epithelium, olfactory bulb, primary olfactory cortices, and their secondary targets.6,7 These issues have been extensively reviewed1–7 and only some salient points are emphasized here. ### Olfactory receptor cells and sensory transduction. The olfactory sensory neurons form clusters interposed among patches of respiratory neuroepithelium.1 These neurons are bipolar cells with a dendritic end containing 3–50 cilia that project into the overlying mucus; their unmyelinated axons form bundles that project through the cribriform plate and synapse in the olfactory bulb.1,2 Odorants bind to guanine nucleotide binding (G) protein–coupled receptors located in the cilia of the olfactory receptor neuron. There are about 400 types of receptors expressed in human olfactory neurons and an individual olfactory sensory neuron typically responds to more than one odorant type.1,5 The first step in olfactory signal transduction is the activation of the Gαolf, which stimulates adenylyl cyclase 3 and production of cyclic adenosyl monophosphate (figure). This triggers opening of a cyclic nucleotide–gated channel allowing calcium (Ca2+) influx and depolarization; subsequent opening of Ca2+ activated chloride (Cl−) channels elicits Cl− efflux that amplifies the depolarization of the sensory neuron.1 The olfactory receptor neurons have several unique features: they can regenerate; serve both as odorant-selective receptor cells and first-order neurons; and are directly exposed to the external environment, thus providing a primary route for invasion into the brain by viruses or toxins.5 …