Name: measurement &amp; analysis of the temporal discrimination threshold applied to cervical dystonia
Uploaded: 2018-01-27T13:00:00
Description: Watch this Scientific Journal Video about Measurement & Analysis of the Temporal Discrimination Threshold Applied to Cervical Dystonia at JoVE.com

This research was supported by grants from the Health Research Board, Dystonia Ireland, Science Foundation Ireland and the Irish Institute for Clinical Neuroscience.

The Medical Research Ethics Committee at St. Vincent&#39;s University Hospital, Dublin gave approval for the recruitment of patients with cervical dystonia, their siblings (unaffected by dystonia), and healthy controls, to participate in the protocol described below.

1. Hardware &#38; Software Solutions
Note: Two hardware options have been developed to display visual stimuli with precise inter-stimulus intervals. Both were designed and built in-house at the Tr...

<ol>
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TDT Measurement and Analysis 
Two forms of apparatus (table-top and headset), two methods of stimulus presentation (staircase and random), and two approaches to data analysis (traditional and distribution) have been presented to illustrate how to measure and quantify a person&#39;s temporal discrimination ability. The portable headset provides a convenient hardware option that ensures consistency in distance and angles between the participant and the LED light sources while al...

Temporal discrimination describes a person&#39;s ability to discriminate, or perceive, rapid changes in their environment. The temporal discrimination threshold (TDT) is the shortest time interval at which an individual can perceive that two sequential sensory stimuli are asynchronous. Temporal discrimination has been shown to be abnormally prolonged in disorders affecting the basal ganglia, including dystonia1,2,3,4,5,6,7.
Dystonia is the third most common neurological movement disorder - after Parkinson&#39;s disease and Essential Tremor. It is characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements or postures8. Dystonia can affect any part of the body. When it affects one body part it is known as focal dystonia8. Dystonia affecting the neck muscles is known as cervical dystonia, and is the most common phenotype of adult onset idiopathic isolated focal dystonia.9,10 The pathogenesis of cervical dystonia remains unknown; it is considered to be a genetic disorder with autosomal dominant inheritance and markedly reduced penetrance. Environmental factors are also considered important in relation to disease penetrance and expression.
The superior colliculus, a sensorimotor structure situated in the dorsal midbrain, is important for the rapid detection of environmental stimuli in the process of covert attentional orienting2,11,12. Visual stimuli access the superior colliculus rapidly through the retino-tectal magnocellular pathway. The TDT is a simple, objective measure believed to represent the processing of visual (and other sensory stimuli) in the superficial layers of the superior colliculus. The TDT has been studied in individuals with cervical dystonia, their unaffected relatives and healthy control participants. Compared to age- and sex-matched control participants, an abnormal TDT has high sensitivity (97%, 36 of 37 patients) and specificity (98-100%) in cervical dystonia1. An abnormal TDT has been found in 50% of unaffected first-degree female relatives of patients with cervical dystonia (14 of 25, aged 48 years or older), demonstrating age- and sex-related penetrance with autosomal dominant inheritance13,14. An abnormal TDT in unaffected relatives of cervical dystonia patients (compared to relatives with normal TDTs) is associated with increased putaminal volume (by voxel-based morphometry)15 and reduced putaminal activity (by fMRI)4. The superior colliculus is considered a significant node in the neuronal network, which is dysfunctional in cervical dystonia12. The assessment of temporal discrimination is regarded as providing important clues as to the pathomechanisms underlying cervical dystonia.
The goal of this article is to present two methods for measuring and analyzing temporal discrimination, as well as demonstrating the application of this method to studying the pathophysiology of cervical dystonia.

<table border="0" cellpadding="0" cellspacing="0" width="1057">
	<tbody>
		<tr height="86">
			<td height="86" style="height:87px;width:216px;">TDT head set</td>
			<td style="width:555px;">Can be supplied by Trinity Centre for Bioengineering, Trinity College Dublin.&#160; Alternatively full instructions are available for free download from http://www.dystoniaresearch.ie/temporal-discrimination-threshold/</td>
			<td style="width:119px;">1</td>
			<td style="width:167px;">A custom-built, portable device for the presentation of visual stimuli.</td>
		</tr>
		<tr height="82">
			<td height="82" style="height:83px;width:216px;">TDT table top LED box</td>
			<td style="width:555px;">Can be supplied by Trinity Centre for Bioengineering, Trinity College Dublin.&#160; Alternatively full instructions are available for free download from http://www.dystoniaresearch.ie/temporal-discrimination-threshold/</td>
			<td style="width:119px;">2</td>
			<td>A custom-built, table-top device for the presentation of visual stimuli.</td>
		</tr>
		<tr height="88">
			<td height="88" style="height:89px;width:216px;">Microcontroller</td>
			<td style="width:555px;">Can be supplied by Trinity Centre for Bioengineering, Trinity College Dublin.&#160; Alternatively full instructions are available for free download from http://www.dystoniaresearch.ie/temporal-discrimination-threshold/</td>
			<td style="width:119px;">3</td>
			<td>A custom-built microcontroller for the delivery of visual stimuli in staircase or random order, with precise inter-stimulus intervals.</td>
		</tr>
	</tbody>
</table>

measurement &amp; analysis of the temporal discrimination threshold applied to cervical dystonia

The temporal discrimination threshold (TDT) is the shortest time interval at which an observer can discriminate two sequential stimuli as being asynchronous (typically 30-50 ms). It has been shown to be abnormal (prolonged) in neurological disorders, including cervical dystonia, a phenotype of adult onset idiopathic isolated focal dystonia. The TDT is a quantitative measure of the ability to perceive rapid changes in the environment and is considered indicative of the behavior of the visual neurons in the superior colliculus, a key node in covert attentional orienting. This article sets out methods for measuring the TDT (including two hardware options and two modes of stimuli presentation). We also explore two approaches of data analysis and TDT calculation. The application of the assessment of temporal discrimination to the understanding of the pathogenesis of cervical dystonia and adult onset idiopathic isolated focal dystonia is also discussed.

Examples of filled score sheets are provided in Tables 1 and 2, where these respectively represent results following staircase and random stimulus presentation methods. The thresholds for each run (the timing of the first of three stimulus pairs deemed to be &#39;different&#39;), are highlighted. In the case of Table 1, the TDT is calculated as 25 ms (i.e., the median of 40, 25, 25, 25, 45, 25, 40, 10 ms). These ...

Watch this Scientific Journal Video about Measurement & Analysis of the Temporal Discrimination Threshold Applied to Cervical Dystonia at JoVE.com

Measurement &amp; Analysis of the Temporal Discrimination Threshold Applied to Cervical Dystonia

Methods for the measurement and analysis of the temporal discrimination threshold are presented, and its application to the study of the pathogenesis of cervical dystonia are discussed.

The temporal discrimination threshold (TDT) is the shortest time interval at which an observer can discriminate two sequential stimuli as being ...

Measurement and analysis of the temporal discrimination threshold applied to cervical dystonia. Detection of environmental change is key to survival. Our ability to perceive such change and react quickly depends on a network within the midbrain.This important network issues motor commands and responds to environmental change and directs our attention in a reflexive manner. The term temporal discrimination describes a person's ability to discriminate or perceive rapid changes in their environment. The goal of this article is to present two methods for the measurement and analysis of temporal discrimination and to demonstrate the application of this technique to the study of cervical dystonia.The temporal discrimination threshold is the shortest time interval at which an observer can discriminate between two asynchronous stimuli and perceives them as occurring separately. Temporal discrimination has been shown to be abnormal or prolonged in disorders affecting the basal ganglia including dystonia. Dystonia is the third most common movement disorder after Parkinson's disease and essential tremor.It is characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive movements or postures. The pathogenesis of cervical dystonia remains unknown. Dystonia can affect any part of the body.When it affects one body part, it is known as focal dystonia. Dystonia affecting the neck muscles is known as cervical dystonia and is the most common form of adult-onset focal dystonia. The temporal discrimination threshold is being measured in individuals with cervical dystonia, their unaffected relatives, and healthy controls.It is believed that this technique can provide insight into the activity of the visual sensory neurons in the superficial layers of the superior colliculus and that this insight can perhaps provide clues as to the underlying pathomechanisms of cervical dystonia. The visual stimuli, two yellow LEDs, are encased in custom-built hardware solutions that enable the stimuli to be presented with the desired millisecond interstimulus intervals. Two hardware options have been developed.The first is the traditional laboratory-based tabletop method in which the LEDs are positioned seven degrees from the subject's center point on the left and right sides. This experiment is conducted in a darkened room. The second hardware solution is a portable headset which enables testing at any location.This hardware solution provides consistency in distance and angles between stimuli and participant. Following presentation of each stimulus pair, the participant responds same or different depending on whether they perceive the stimuli to be synchronous or asynchronous. The standard approach to stimulus presentation is a staircase approach.This method involves presenting the individual with progressively asynchronous stimuli. Stimuli are presented every five seconds with the interstimulus interval increasing by five milliseconds each time. The trial ends when a participant responds different for three consecutive pairs of stimuli.The experiment is repeated four times on the left and right resulting in a total of eight runs. The temporal discrimination threshold is calculated by taking the median of the thresholds from each of the eight runs for that individual. Due to a potential learning effect in the staircase method, we developed a method of randomized presentation order.The stimuli pairs are still presented every five seconds, but the interstimulus interval varies in a randomized fashion from zero to 100 milliseconds. The standard method of analyzing temporal discrimination data results in a single value expressed in milliseconds. We use this value to calculate the zed score for each individual.The zed score is defined as the difference between the participant's Temporal Discrimination Threshold or TDT value and the mean TDT from an age-matched control population divided by the standard deviation of the TDT values for that control population. TDT values resulting in zed scores above 2.5 are deemed to be abnormal. While this approach has been widely used and the TDT has been shown to be a strong and selective endophenotype, it is nonetheless a single value.To fully characterize a participant's data, we expanded our analysis to fit their data to a cumulative Gaussian distribution. The mean of this distribution represents the point at which participants are equally likely to respond same or different. This point is referred to as the Point of Subjective Equality.The standard deviation of the Gaussian distribution, also referred to as the Just Noticeable Difference, indicates how sensitive participants are to changes in temporal asynchrony around their mean. The method is strengthened by submitting the data to a non-parametric bootstrap analysis to get 95%confidence intervals for each participant. Both metrics correlate with the temporal discrimination threshold, but are independent of each other.This analysis method has the potential to reveal subtle differences between the patient and control group that may not be apparent from the standard method. Causative genes have been identified in less than 1%of adult-onset focal dystonia cases. An endophenotype is a subclinical marker of genetic carriage which can help us to understand disease pathomechanisms.The temporal discrimination threshold, a potential endophenotype for adult-onset focal dystonia, is abnormal in up to 97%of patients and approximately 50%of their clinically unaffected relatives. In addition, an abnormal TDT follows an age and sex-related pattern similar to that of cervical dystonia. These findings suggest autosomal-dominant inheritance and support the use of the TDT as an endophenotype for adult-onset focal dystonia and in particular cervical dystonia.An abnormal TDT can be interpreted as an impaired ability to detect or discriminate environmental change. The superior colliculus located at the back of the midbrain plays a critical role in detecting and reacting to salient stimuli. Let's take a closer look at this structure.The superior colliculus is a paired laminated structure situated in the dorsal midbrain. It is the primary brainstem center for transforming spatial information of target location and to orienting head and eye movement. The superior colliculus consists of several layers with distinct organization.However, it can be functionally separated into a superficial and deep layer. The superficial layer receives direct input from the visual system and contains a topographic map of the surrounding world in retinotopic coordinates. The visio-sensory neurons respond to salient environmental stimuli which in turn encode the location of objects in a retinotopic map.The premotor neurons in the deep layer project to other brain regions which when they become excited fire at high frequencies generating quick eye movements known as saccades in the direction of the target. The deep layer also contains motor neurons which project to the upper cervical cord via the tectospinal pathway. When these neurons are activated, the head turns towards the target.Superior collicular activity is modulated by gamma-aminobutyric acid or GABA, an inhibitory neurotransmitter. Inhibitory GABAergic activity limits the duration of the transient response in both the visual sensory neurons in the superficial layer and the premotor neurons in the deep layer of the superior colliculus. In response to a visual stimulus, most of the neurons in the superficial layer exhibit a transient on response.GABAergic inhibition then silences this response enabling the neurons to be ready to respond again when the visual stimulus is turned off. If there is insufficient GABA, these neurons may become dysfunctionally active. It is hypothesized that insufficient GABAergic inhibition results in prolonged duration firing of visio-sensory neurons giving rise to abnormal temporal discrimination.In addition, the abnormal movements characteristic of cervical dystonia are hypothesized to also result in insufficient GABAergic inhibition causing prolonged firing of the motor neurons in the deep layers of the superior colliculus. We have demonstrated that temporal discrimination can be measured in a straightforward and efficient manner and that this simple tool is a reliable endophenotype for cervical dystonia. In addition, it can potentially provide insight into the pathomechanisms of this disorder.

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T-maze Forced Alternation and Left-right Discrimination Tasks for Assessing Working and Reference Memory in Mice

Forced alternation and left-right discrimination tasks using the T-maze have been widely used to assess working and reference memory, respectively, in rodents. In our laboratory, we evaluated the two types of memory in more than 30 strains of genetically engineered mice using the automated version of this apparatus. Here, we present the modified T-maze apparatus operated by a computer with a video-tracking system and our protocols in a movie format. The T-maze apparatus consists of runways partitioned off by sliding doors that can automatically open downward, each with a start box, a T-shaped alley, two boxes with automatic pellet dispensers at one side of the box, and two L-shaped alleys. Each L-shaped alley is connected to the start box so that mice can return to the start box, which excludes the effects of experimenter handling on mouse behavior. This apparatus also has an advantage that in vivo microdialysis, in vivo electrophysiology, and optogenetics techniques can be performed during T-maze performance because the doors are designed to go down into the floor. In this movie article, we describe T-maze tasks using the automated apparatus and the T-maze performance of &alpha;-CaMKII+/- mice, which are reported to show working memory deficits in the eight-arm radial maze task. Our data indicated that &alpha;-CaMKII+/- mice showed a working memory deficit, but no impairment of reference memory, and are consistent with previous findings using the eight-arm radial maze task, which supports the validity of our protocol. In addition, our data indicate that mutants tended to exhibit reversal learning deficits, suggesting that &alpha;-CaMKII deficiency causes reduced behavioral flexibility. Thus, the T-maze test using the modified automatic apparatus is useful for assessing working and reference memory and behavioral flexibility in mice.

This article presents the protocol of T-maze tests using a modified automated apparatus for assessing the learning and memory functions in mice.

Forced alternation and left-right discrimination tasks using the T-maze have been widely used to assess working and reference memory, respectively, in ...

Rapid Determination of the Thermal Nociceptive Threshold in Diabetic Rats

Painful diabetic neuropathy (PDN) is characterized by hyperalgesia i.e., increased sensitivity to noxious stimulus, and allodynia i.e., hypersensitivity to normally innocuous stimuli1. Hyperalgesia and allodynia have been studied in many different rodent models of diabetes mellitus2. However, as stated by B&ouml;lcskei et al, determination of "pain" in animal models is challenging due to its subjective nature3. Moreover, the traditional methods used to determine behavioral responses to noxious thermal stimuli usually lack reproducibility and pharmacological sensitivity3. For instance, by using the hot-plate method of Ankier4, flinch, withdrawal and/or licking of either hind- and/or fore-paws is quantified as reflex latencies at constant high thermal stimuli (52-55 &deg;C). However, animals that are hyperalgesic to thermal stimulus do not reproducibly show differences in reflex latencies using those supra-threshold temperatures3,5. As the recently described method of B&ouml;lcskei et al.6, the procedures described here allows for the rapid, sensitive and reproducible determination of thermal nociceptive thresholds (TNTs) in mice and rats. The method uses slowly increasing thermal stimulus applied mostly to the skin of mouse/rat plantar surface. The method is particularly sensitive to study anti-nociception during hyperalgesic states such as PDN. The procedures described bellow are based on the ones published in detail by Alm&aacute;si et al 5 and B&ouml;lcskei et al 3. The procedures described here have been approved the Laboratory Animal Care and Use Committee (LACUC), Wright State University.

Here, we describe a rapid reliable and simple procedure to determine the lowest temperature at which rats or mice show nocifensive behavior, i.e. the thermal nociceptive threshold (TNT). This method applies a slowly increasing thermal stimulus allowing precise and reproducible estimation of TNTs with minimum, if any, stress to the animals.

Painful diabetic neuropathy (PDN) is characterized by hyperalgesia i.e., increased sensitivity to noxious stimulus, and allodynia i.e., hypersensitivity ...

A Galvanotaxis Assay for Analysis of Neural Precursor Cell Migration Kinetics in an Externally Applied Direct Current Electric Field

The discovery of neural stem and progenitor cells (collectively termed neural precursor cells) (NPCs) in the adult mammalian brain has led to a body of research aimed at utilizing the multipotent and proliferative properties of these cells for the development of neuroregenerative strategies. A critical step for the success of such strategies is the mobilization of NPCs toward a lesion site following exogenous transplantation or to enhance the response of the endogenous precursors that are found in the periventricular region of the CNS. Accordingly, it is essential to understand the mechanisms that promote, guide, and enhance NPC migration. Our work focuses on the utilization of direct current electric fields (dcEFs) to promote and direct NPC migration - a phenomenon known as galvanotaxis. Endogenous physiological electric fields function as critical cues for cell migration during normal development and wound repair. Pharmacological disruption of the trans-neural tube potential in axolotl embryos causes severe developmental malformations1. In the context of wound healing, the rate of repair of wounded cornea is directly correlated with the magnitude of the epithelial wound potential that arises after injury, as shown by pharmacological enhancement or disruption of this dcEF2-3. We have demonstrated that adult subependymal NPCs undergo rapid and directed cathodal migration in vitro when exposed to an externally applied dcEF. In this protocol we describe our lab's techniques for creating a simple and effective galvanotaxis assay for high-resolution, long-term observation of directed cell body translocation (migration) on a single-cell level. This assay would be suitable for investigating the mechanisms that regulate dcEF transduction into cellular motility through the use of transgenic or knockout mice, short interfering RNA, or specific receptor agonists/antagonists.

In this protocol we demonstrate how to construct custom chambers that permit the application of a direct current electric field to enable time-lapse imaging of adult brain derived neural precursor cell translocation during galvanotaxis.

The discovery of neural stem and progenitor  cells (collectively termed neural precursor cells) (NPCs) in the adult  mammalian brain has led to a body of ...

The Dig Task: A Simple Scent Discrimination Reveals Deficits Following Frontal Brain Damage

Cognitive impairment is the most frequent cause of disability in humans following brain damage, yet the behavioral tasks used to assess cognition in rodent models of brain injury is lacking. Borrowing from the operant literature our laboratory utilized a basic scent discrimination paradigm1-4 in order to assess deficits in frontally-injured rats. Previously we have briefly described the Dig task and demonstrated that rats with frontal brain damage show severe deficits across multiple tests within the task5. Here we present a more detailed protocol for this task. Rats are placed into a chamber and allowed to discriminate between two scented sands, one of which contains a reinforcer. The trial ends after the rat either correctly discriminates (defined as digging in the correct scented sand), incorrectly discriminates, or 30 sec elapses. Rats that correctly discriminate are allowed to recover and consume the reinforcer. Rats that discriminate incorrectly are immediately removed from the chamber. This can continue through a variety of reversals and novel scents. The primary analysis is the accuracy for each scent pairing (cumulative proportion correct for each scent). The general findings from the Dig task suggest that it is a simple experimental preparation that can assess deficits in rats with bilateral frontal cortical damage compared to rats with unilateral parietal damage. The Dig task can also be easily incorporated into an existing cognitive test battery. The use of more tasks such as this one can lead to more accurate testing of frontal function following injury, which may lead to therapeutic options for treatment. All animal use was conducted in accordance with protocols approved by the Institutional Animal Care and Use Committee.

In this protocol, a novel application of scent discrimination is described. The Dig task is a reasonably inexpensive task that can be used to assess frontally-mediated cognition following brain damage.

Cognitive impairment is the most frequent cause of disability in humans following brain damage, yet the behavioral tasks used to assess cognition in ...

A Comprehensive Protocol for Manual Segmentation of the Medial Temporal Lobe Structures

The present paper describes a comprehensive protocol for manual tracing of the set of brain regions comprising the medial temporal lobe (MTL): amygdala, hippocampus, and the associated parahippocampal regions (perirhinal, entorhinal,&#160;and parahippocampal proper). Unlike most other tracing protocols available, typically focusing on certain MTL areas (e.g., amygdala and/or hippocampus), the integrative perspective adopted by the present tracing guidelines allows for clear localization of all MTL subregions. By integrating information from a variety of sources, including extant tracing protocols separately targeting various MTL structures, histological reports, and brain atlases, and with the complement of illustrative visual materials, the present protocol provides an accurate, intuitive, and convenient guide for understanding the MTL anatomy. The need for such tracing guidelines is also emphasized by illustrating possible differences between automatic and manual segmentation protocols. This knowledge can be applied toward research involving not only structural MRI investigations but also structural-functional colocalization and fMRI signal extraction from anatomically defined ROIs, in healthy and clinical groups alike.

The present work provides a comprehensive set of guidelines for manually tracing the medial temporal lobe (MTL) structures. This protocol can be applied to research involving structural and/or combined structural-functional magnetic resonance imaging (MRI) investigations of the MTL, in both healthy and clinical groups.

The present paper describes a comprehensive protocol for manual tracing of the set of brain regions comprising the medial temporal lobe (MTL): amygdala, ...

Diffusion Imaging in the Rat Cervical Spinal Cord

Magnetic resonance imaging (MRI) is the state of the art approach for assessing the status of the spinal cord noninvasively, and can be used as a diagnostic and prognostic tool in cases of disease or injury. Diffusion weighted imaging (DWI), is sensitive to the thermal motion of water molecules and allows for inferences of tissue microstructure. This report describes a protocol to acquire and analyze DWI of the rat cervical spinal cord on a small-bore animal system. It demonstrates an imaging setup for the live anesthetized animal and recommends a DWI acquisition protocol for high-quality imaging, which includes stabilization of the cord and control of respiratory motion. Measurements with diffusion weighting along different directions and magnitudes (b-values) are used. Finally, several mathematical models of the resulting signal are used to derive maps of the diffusion processes within the spinal cord tissue that provide insight into the normal cord and can be used to monitor injury or disease processes noninvasively.

The goal of this protocol is to obtain high-quality diffusion weighted magnetic resonance imaging (DWI) of the rat spinal cord for noninvasive characterization of tissue microstructure. This protocol describes optimizations of the MRI sequence, radiofrequency coil, and analysis methods to enable DWI images free from artifacts.

Magnetic resonance imaging (MRI) is the state of the art approach for assessing the status of the spinal cord noninvasively, and can be used as a ...

In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model

One way that solid tumors disseminate is through neural invasion. This route is well-known in cancers of the head and neck, prostate, and pancreas. These neurotropic cancer cells have a unique ability to migrate unidirectionally along nerves towards the central nervous system (CNS). The dorsal root ganglia (DRG)/cancer cell model is a three dimensional (3D) in vitro model frequently used for studying the interaction between neural stroma and cancer cells. In this model, mouse or human cancer cell lines are grown in ECM adjacent to preparations of freshly dissociated cultured DRG. In this article, the DRG isolation protocol from mice, and implantation in petri dishes for co-culturing with pancreatic cancer cells are demonstrated. Five days after implantation, the cancer cells made contact with the DRG neurites. Later, these cells formed bridgeheads to facilitate more extensive polarized, neurotropic migration of cancer cells.

In Vitro Modeling of Cancerous Neural Invasion: The Dorsal Root Ganglion Model

This video article shows the use of the dorsal root ganglia (DRG)/cancer cell model in pancreatic ductal adenocarcinoma.

One way that solid tumors disseminate is through neural invasion. This route is well-known in cancers of the head and neck, prostate, and pancreas. These ...

High Resolution Quantitative Synaptic Proteome Profiling of Mouse Brain Regions After Auditory Discrimination Learning

The molecular synaptic mechanisms underlying auditory learning and memory remain largely unknown. Here, the workflow of a proteomic study on auditory discrimination learning in mice is described. In this learning paradigm, mice are trained in a shuttle box Go/NoGo-task to discriminate between rising and falling frequency-modulated tones in order to avoid a mild electric foot-shock. The protocol involves the enrichment of synaptosomes from four brain areas, namely the auditory cortex, frontal cortex, hippocampus, and striatum, at different stages of training. Synaptic protein expression patterns obtained from trained mice are compared to na&#239;ve controls using a proteomic approach. To achieve sufficient analytical depth, samples are fractionated in three different ways prior to mass spectrometry, namely 1D SDS-PAGE/in-gel digestion, in-solution digestion and phospho-peptide enrichment. 
High-resolution proteomic analysis on a mass spectrometer and label-free quantification are used to examine synaptic protein profiles in phospho-peptide-depleted and phospho-peptide-enriched fractions of synaptosomal protein samples. A commercial software package is utilized to reveal proteins and phospho-peptides with significantly regulated relative synaptic abundance levels (trained/na&#239;ve controls). Common and differential regulation modes for the synaptic proteome in the investigated brain regions of mice after training were observed. Subsequently, meta-analyses utilizing several databases are employed to identify underlying cellular functions and biological pathways.

The identification of molecules and pathways controlling synaptic plasticity and memory is still a major challenge in neuroscience. Here, a workflow is described addressing the relative quantification of synaptic proteins supposedly involved in the molecular reorganization of synapses during learning and memory consolidation in an auditory learning paradigm.

The molecular synaptic mechanisms underlying auditory learning and memory remain largely unknown. Here, the workflow of a proteomic study on auditory ...

An Objective and Reproducible Test of Olfactory Learning and Discrimination in Mice

Olfaction is the predominant sensory modality in mice and influences many important behaviors, including foraging, predator detection, mating, and parenting. Importantly, mice can be trained to associate novel odors with specific behavioral responses to provide insight into olfactory circuit function. This protocol details the procedure for training mice on a Go/No-Go operant learning task. In this approach, mice are trained on hundreds of automated trials daily for 2&#8211;4 weeks and can then be tested on novel Go/No-Go odor pairs to assess olfactory discrimination, or be used for studies on how odor learning alters the structure or function of the olfactory circuit. Additionally, the mouse olfactory bulb (OB) features ongoing integration of adult-born neurons. Interestingly, olfactory learning increases both the survival and synaptic connections of these adult-born neurons. Therefore, this protocol can be combined with other biochemical, electrophysiological, and imaging techniques to study learning and activity-dependent factors that mediate neuronal survival and plasticity.

Here, we train mice on an associative learning task to test odor discrimination. This protocol also allows for studies on learning-induced structural changes in the brain.

Olfaction is the predominant sensory modality in mice and influences many important behaviors, including foraging, predator detection, mating, and ...

The Power of Interstimulus Interval for the Assessment of Temporal Processing in Rodents

Temporal processing deficits have been implicated as a potential elemental dimension of higher-level cognitive processes, commonly observed in neurocognitive disorders. Despite the popularization of prepulse inhibition (PPI) in recent years, many current protocols promote using a percent of control measure, thereby precluding the assessment of temporal processing. The present study used cross-modal PPI and gap prepulse inhibition (gap-PPI) to demonstrate the benefits of employing a range of interstimulus intervals (ISIs) to delineate effects of sensory modality, psychostimulant exposure, and age. Assessment of sensory modality, psychostimulant exposure, and age reveals the utility of an approach varying the interstimulus interval (ISI) to establish the shape of the ISI function, including increases (sharper curve inflections) or decreases (flattening of the response amplitude curve) in startle amplitude. Additionally, shifts in peak response inhibition, suggestive of a differential sensitivity to the manipulation of ISI, are often revealed. Thus, the systematic manipulation of ISI affords a critical opportunity to evaluate temporal processing, which may reveal the underlying neural mechanisms involved in neurocognitive disorders.

Temporal processing, a preattentive process, may underlie deficits in higher-level cognitive processes, including attention, commonly observed in neurocognitive disorders. Using prepulse inhibition as an exemplar paradigm, we present a protocol for manipulating interstimulus interval (ISI) to establish the shape of the ISI function to provide an assessment of temporal processing.