What is extra-dimensional measurement freedom

An operant intra / extra dimensional set-shift task for mice

Introduction

Attention Rate Shift is a measure of cognitive flexibility and executive function 1. It refers to the ability to switch between any internal rules ("cognitive attention sets"). The most commonly used neuropsychological tasks for measuring attention set-shifting and cognitive flexibility in humans are the Wisconsin Card Sorting Test (WCST) 2 and a newer and more refined version: the intra- and extra-dimensional attention set-shifting (ID / ED) of the Cambridge neuropsychological test automatic battery (CANTAB) 3,4. These tasks were used to identify specific cognitive abnormalities in a wide range of mental disorders including autism 5,6 Schizophrenia, Parkinson's disease 7, Obsessive-compulsive disorder 8 and Attention Deficit / Hyperactive Disorder 9 to identify. The clinical relevance and solid methodological approach of the WCST and the ID / ED tests attracted interest in performing similar tests in preclinical research 10,11. These tasks enable the selective measurement of different cognitive abilities in the same subject such as discriminatory learning, reversal learning, formation of an attention sentence, shifting of attention within the same dimension (. Ie Intradimension change: IDS) and between the different dimensions of perception (ie, extra-dimensional shift: EDS). This is crucial because different brain circuits as well as neuropathology could alter these different cognitive functions in different ways. For example, a double division or functional specialization has shown an effect between the lateral (in monkeys and humans) / medial (in rodents) and orbital areas of the PFC in the set of displacement tasks under consideration. While the orbitofrontal cortex is involved in the reverse phases of these tasks, the lateral / medial PFC region regulates the extra-dimensional switching stages12-14.

Rodent versions of these primate attention set shifting tests have been successfully generated 13-16. However, some aspects of these rodent versions have been limiting their applications and uses. For example, these tasks are performed manually and are therefore very labor intensive and difficult to standardize. In addition, the presence of food enhancers in the stimuli could be in an ambiguous interpretation of the animal responses and potential bias of choice 10 to lead. These characteristics have limited the throughput of the test and, more importantly, its large-scale application of genetic and / or drug screening studies.

To overcome these limitations and to improve the application possibilities of the ID / ED switching paradigms in rodents, here we present a new two-chamber operant based task to test cognitive flexibility in mice. This new task mimics the ID / ED task used in human and nonhuman primates and bypasses the problems of the earlier rodent versions.

Protocol

All procedures were approved by the Italian Ministry of Health and local Animal Use Committee and were carried out in accordance with the guide for the care and use of laboratory animals of the guidelines of the Council of the European Community.

Note: Figure 6 shows a timeline of the entire procedure of the protocol to test the ID / ED task.

1. Devices

Figure 1. The two-chamber "Operon" Device.(A) View from the top of the entire device and (B) Front view from a single chamber mimicking the mouse point-of-view during the test. 1: visual stimuli (LEDs); 2: food magazine; 3: nostril sac; 4: touch stimulus (nature); 5: odor stimuli; 6: automatic sliding door; 7: house -Light; 8: Infrared photo beam for door control. Chambers (16 x 16 x 16 cm 3) from separated by a transparent plastic door (6). Infrared photobeams (8) tracks the animals' movements and controls the opening / closing of the automatic door to allow the mouse to change chambers. Each chamber has two nostrils sack (3) with infrared photobeams, and between these, a food magazine (2) with photobeams where a pellet dispenser delivered the food reinforcement. A house light (7) is located above each of the two food magazines. Each nose sack hole is equipped with a number of changing stimuli that could vary in three different perceptual dimensions (smell, sight, tact). Originally in 'The ultimate intra- and extra-dimensional attention set-shifting task for Mice "19released.Please click here to see a larger version of this figure.

content "> Note: The Operon device (Illustration 1) consists of two identical chambers with plexiglass walls and an aluminum floor (16 x 16 x 16 cm 3 for each chamber) chambers are separated by a transparent plexiglass partition door that can be. controlled the mouse to allow access to either chamber. Each chamber has two nasal-poke holes with infrared photobeams, and in between, a food journal with photobeams where a pellet dispenser delivered the food reinforcement. A fan and house light are located above each of the two food magazines.
  1. Equip each nostril sac with a number of changing stimuli (Table 1) in three different dimensions of perception (i.e., smell, Sight, tactile) vary. Note: the stimuli in Table 1 suggested to avoid any confusion factor and / or bias through avoidance or preference has been chosen. Five pairs of copies for the individual dimensions enable a mitin-topic examination of all layers, with new stimuli with each shift.
    1. Around Odor stimuli To deliver into the sack nostrils, use a dilution olfactometer to condition the air supply to the sack nostrils by automatically desiccating, filtering, rehydrating and controlling the appearance of pairs of scents.
      1. Use an olfactometer to control two nostrils poke. Regulate air flow through an air pump and vacuum to remove the odor in the nostrils sack. The air pump to the inlet of the olfactometer and the vacuum to the sockets attached to the nasal pickup device. Then close the valve for odor delivery on each Nasal Poke inlet. Set the flow rate to 1.5 liters per minute.
      2. Dilute Odor Odors 1:20 in mineral oil and fill the bottles with the olfactometer.
    2. For visual stimuli, Place light emitting diodes (LED) on each nasal sac hole and attach them to the metal panel of the chamber (see details in Illustration 1 and table1). Connect to the output interface.
    3. For tactile stimuli, assemble changeable ground textures in front of each nostril sac. Assemble the various textures on the sled and move them with frames under the floor so that they line up with a small opening (3 x 3 cm 2) Poke presented on the floor in front of each nostril.
  2. Control the presentation of the stimuli using software according to the manufacturer's instructions to automatically change the stimuli of the various dimensions during the experiment.
  3. Place a camera on top of the device to record basal variety and locomotive activity using behavior monitoring software (e.g. B. Ethovision, Anymaze) that could help to eliminate animals that have problems unrelated to cognitive functions.
SMELLSTEXTURESLIGHTING
Peach v. sage Velcro v. Movie Lights on v. light off
Vanilla v. lavender coarse sandpaper v. fine sandpaper red v. green
Strawberry v. cinnamon smooth cardboard v. corrugated cardboard blue v. yellow
Grapefruit v. oregano Sponge v. smooth plastic Orange v. white
Lemon v. apricot honeycomb paper v. Aluminum foil fix lit v. Flashing lights

Table 1 copy in the ID / ED Operon task used. Compound discrimination will be based on fixed combinations of pairs of specimens (please refer 2 for an example of the sequence of distinctions). The exemplary pairs from different dimensions are presented in random combinations. Neutral stimuli for the various dimensions are: air flow without fragrance; White paper; no light stimuli. Table originally published in "The Ultimate Intra- and Extra-Dimensional Attention Set-Shifting Task for Mice"19.

2. Preparation of the animals

Note: The representative results reported here were obtained from male C57BL / 6J mice, 3-7 months old, during the light phase.

  1. Weigh the mouse, just house it and then hand it for 1 min every other day.
  2. After a week of acclimatization to single-case, plate body weight and 24-hour food intake for three consecutive days to determine baseline weight and food intake.
  3. Apply a light food deprivation regime for 1 week before training for the test. Check animal weights each day while feeding food during the experiment in order to keep limited to about 90% of their starting free-feeding body weight. Three consecutive days before the habituation training phase, mice also give ≈20 food-boosting pellets in their home cage. These are the feed pellets to be used in subsequent tests.
    Note: Food restriction is used to increase the motivation of the animals to work on the task, however, do not exceed 10% of the weight loss at any stage of the entire procedure as it will lead to abnormal behaviors and excessive stress on the mice that are can affect the results.
    1. As an alternative to avoiding single housing, leave the mice housed in groups (2 to 4 of each cage) and allow access to them ad libitum Food for a period of time after the test. Check animal weights each day while feeding food during the experiment in order to keep body weights limited to about 90% of their starting free.

3. Habituation

  1. Train-the-mice in a 1-day session of 40 min to move inside the device without the door divider, where a nasal sac in each nasal poke hole leads to a pellet delivery in the food intake. During this phase you only use neutral stimuli (Table 1) for all different dimensions (Habituation 1).
  2. The following day, train the animals for 40 minutes to move from one chamber to the other at the end of each study (Habituation 2). Use only neutral stimuli for all different dimensions. Also at this stage, a nasal stuck in each of the nasal poke holes leads to a pellet delivery in the food magazine. When the mouse gets the reward in the food magazine, lower the intermediate door, the mouse accessing the other chamber for the next attempt give.
  3. On the third day (Habituation 3), train the animals to perform two simple discrimination (SD1 and SD2, e.g. Velcro film vs; .. Light cue on vs. Light cue off; peach vs. Sage.) On a criterion of the 8 correct answers out of 10 consecutive attempts. Use these copies again in the next stages of the test.
    1. To start, place the mouse in a chamber with neutral stimuli while the stimulus cues are on in the other chamber; Down the door to give the mouse access to the chamber with the activated stimuli clues. The mouse has to learn to choose the nose-sack hole where the correct one is presented. Sessions last 40 minutes.
    2. Reward a nose-sack in the correct hole with a pellet delivery and, when the mouse is in the food magazine, lower the intermediate door the mouse makes access to the other chamber for the next attempt. Have a nose-bag reward in the wrong hole and turn off the house light for 5 seconds. Then lower the door to give the mouse access to the other chamber for the next attempt.
    3. Do the first ten studies with each stage, such as designing studies: if the mouse picks the wrong hole, record an error, but don't stop the attempt until the mouse is also in the correct hole. In subsequent studies, if the mouse is stuck in the wrong hole, record a mistake and turn off all dimensional stimuli to stop the study.
    4. Close each session after 40 minutes or if a mouse fails to make a response for five consecutive minutes, whichever came first. If the mouse does not meet the criterion in one session, run the test the next day.
    5. If a mouse cannot meet the criterion in SD1 or SD2 of Habituation 3 after 5 sessions, stop testing the mouse and eliminate it from the study because it is unable to make basic distinctions that could then affect the results of the ID / ED perform task reliably.

Figure 2. Example of the ID / ED task. An example of the ID / ED “stuck-in-set” and “two-dimension” paradigms are shown. "Of the Ultimate intra- and extra-dimensional attention set-shifting task for mice '19customized.Please click here to see a larger version of this figure.

4. 'Stuck-in-Set' ID / ED Paradigm Order

NOTE: For this procedure, previously in both primates and rodents 7,15,16 is used, it is necessary to manipulate three different dimensions of perception for each individual mouse being tested. As for the habituation period, all test daily sessions begin by placing the mouse in one of the two chambers in which all stimuli are neutral. Before starting a test, the stimulus signals are switched to the opposite chamber. Then the dividing door is lowered to give the mouse access to the other chamber where the stimulus cues are.

  1. To train the animal to develop a sentence, or bias, on a particular dimension of perception (. For example, Smell, light or soil conditions), expose mice to the following distinctions presented in this order (see also an example in Figure 2):
    1. For easy differentiation (SD), introduce mice to a dimension (smell, light or texture, please refer Figure 2), which is relevant in all tasks until the EDS. That said, the relevant dimension is the one that indicates where the correct answer is. According to the example of Figure 2 show two smells like vanilla (O1) and lavender (O2), and choose O1 as the correct answer.
    2. For the combined discrimination (CD), the introduction of a second dimension, for example the light, which is irrelevant (ie not indicating were the correct answer). Present two lights (L1 and L2) together with the smells (O1 and O2) to have two possible discriminations (see example in Figure 2). The correct and incorrect copies are the same as in SD.
    3. For reversing the connection of discrimination (cdre), leave the specimens and the respective measure unchanged, but have the animals learn that the previously correct stimulus is now correct. For example, choose lavender as the correct answer, with vanilla now being the wrong choice. The same conditions apply to the other reversal phases (ie IDSRe, IDS2Re and EDSRe) can be found.
    4. After that, choose an intra-dimensional shift (IDS) in which new specimens are used for both relevant and irrelevant dimensions (a total design change). For example, use strawberries and cinnamon (O3 and O4) as the smells and blue and yellow lights (L3 and L4) as the lights. However, ensure that the test subjects keep following the same relevant dimension in order to find the correct answer. The same conditions are applied to the other intradimensional shift (ie IDS2) can be found.
    5. As with the previous discrimination, the mice performed the Intra-Dimensional Shift Reversal (IDSRe). Use the same conditions as in cdre.
    6. For intra-dimensional displacement 2 (IDS2), use the same conditions as for IDS.
    7. Similarly, the same conditions as in cdre become for the intra-dimensional displacement inversion 2 (IDSRe2).
    8. In Extra-Dimensional Displacement (EDS), the mice were choosing the correct hole according to a newly introduced economic dimension. Present a pair of charms from a new dimension which is texture. For example, use coarse sandpaper (T1) as the correct response and fine sandpaper (T2) as incorrect, and present them with two new smells, for example lemon and apricot (O7 and O8). The previously relevant dimension is now becoming irrelevant. More do not present the previously irrelevant dimension.
    9. For the extra-dimensional inversion (EDSRe), ​​use the same conditions as in cdre.
  2. Measure the performance of the mice until they reach a criterion of 8 correct decisions out of 10 consecutive runs to complete each stage. Set the program (see table of materials) to automatically move to the next level after the criterion is reached. Stop a daily session after 40 minutes, or if a mouse fails to make an answer for 5 consecutive minutes, end the session and move the mouse to the same stage where it left off the next day.
    1. For each level, measure the time it took to meet the criterion. If a mouse does not meet the criterion in one session, summarize the total time taken in consecutive sessions. For any attempt to measure the time from the presentation of the stimuli (smells, lighting, textures) to a nasal poke response (latency to respond).
  3. At the end of each session, wipe the device with 70% alcohol.
  4. Always use the same order of discrimination. However, at random you change the stimulus dimensions and the pairs of specimens used, and likewise represent them in experimental groups and counterbalance them between groups.
  5. Make sure to counterbalance the perceptual dimensions within and between each experimental group as well so that any possible ED shift is represented (ie Light to smell, light texture, smell, light, smell to texture, texture, light, texture to smell). The combinations of specimens are too numerous to allow full compensation; Therefore, to reduce the degrees of freedom, always use copies in pairs; for example vanilla stimulus with lavender etc. (see Table 1).

Note: Another condition used to measure attention set-shifting ability in both primates and rodents 12,1713, is the "two-dimensional" paradigm. In this case, only two dimensions of perception are used during the test.

  1. For this protocol, use the order of discrimination and the procedure to follow as described for the 'stuck-in-set' protocol up to the EDS stage (see an example in Figure 2):
    1. For the SD and subsequent phases, use the same pairs of "stuck-in-set" until the IDS2Re. As in the example of the Figure 2 shown with two smells (O1 and O2, O1 use correct stimulus).
    2. For the CD, as in the 'stuck-in-set' protocol, represent a new dimension (for example light, L1 and L2) that is irrelevant and would serve as a confounder.
    3. The cdre is similar to that of the 'stuck-in-set' protocol, so leave the specimens and respective dimensions unchanged, but have the animals learn that the previously correct stimulus is now incorrect (e.g. O1).
    4. In the IDS, you always use new pairs of stimuli for both dimensions (O3 and O4, L3 and L4, where O3 is the correct stimulus).
    5. For the IDSRe, the mice have to perform the reverse of the IDS. Choose the correct copy, the one that is not correct in the IDS (e.g. O4) was.
    6. For IDS2, introduction of new pairs of stimuli for both dimensions (O5 and O6, L5 and L6).
    7. As in the previous reversal stages, in the IDS2Re, the animals must learn that the previously correct stimulus is now incorrect (e.g. O5).
    8. For the "two-dimension" protocol, the EDS, the mice have to choose the correct answer after the previously irrelevant dimension becomes the corresponding dimension. So is the new light relevant dimension, which gives the correct answer. In particular, red light (L7) is the correct answer. Conversely, the previously relevant dimension (in the example, smell) is now irrelevant one.
    9. After the EDS, for the reversal (EDSRe), ​​use the same conditions as in cdre. The relevant dimension is the same as in the EDS, but the correct and incorrect copies are inverted. For example, the green light (L8) is now the correct response.

6. Data analysis

  1. Measure the performance of: number of attempts to meet the criterion; Time to reach the criterion (in minutes); Time from the presentation of the stimuli to a nasal poke response (latency to respond).
  2. For statistical analysis, use ANOVAs with the different levels (SD, CD, cdre, IDS, IDSRe, IDS2, IDSRe2, EDS and EDSRe) as an intra-individual factor to examine the number of attempts required to achieve the criteria, timing required to respond to each stage and the latency to complete. ConKanal Post hoc analysis with Newman-Keuls test. NOTE: The accepted value for significance is p <0.05.

Representative Results

Figure 2 shows an example of the ID / ED task. Pairs of stimuli (either 'Discrimination 1' or 'Discrimination 2') are shown at random in each stage, and the mouse must choose the correct stimulus in each pair. In this example table, the correct specimen is shown in bold. In the table first stage (SD or simple discrimination), the stimuli presented in the two poke nostrils differed in one of the three dimensions (e.g. O1: Vanilla vs. O2: Lavender) and the mouse is responsible for choosing the right specimen (e.g. O1) rewarded. As soon as the person meets the criterion at this stage, the next stage (CD or combined discrimination) begins, where the same specimens of the dimension in question are randomly superimposed around specimens of a second presented, but irrelevant dimension introduced as a disruptive factor (reached e.g. L1 :. blue light vs L2: yellow light). Two different distinctions are possible at this stage (either 'Discrimination 1' or 'Discrimination 2'). In the next stage (cdre or combined discrimination reversal) the reward eventualities are reversed, but the specimens and the corresponding dimension remain unchanged: the mouse to learn that the previously correct stimulus is now incorrect (e.g. the scent of lavender is now rewarded). In the next stage (IDS or intra-dimensional shift), new specimens (both smells and lights) are introduced, but the corresponding dimension (smell in this example) remains the same (to the Example, strawberry is the right choice). In the next stage (IDR or intra-dimensional reversal) the reward eventualities are reversed. After a second intra-dimensional shift (IDS2 and its inversion), new specimens are introduced to test the extra-dimensional change (EDS), in which the relevant dimension changed. In the "stuck-in-set" EDS, the mouse has taken on a new dimension (e.g. the texture, focus T1: coarse sandpaper against T2: fine sandpaper), while the previously relevant dimension (in this case, odor) is now the irrelevant dimension. In the "two-dimensional" EDS, the previously irrelevant dimension (in this case light) is now the relevant dimension. In the final stage (EDSRe or Extra-Dimensional Reversal) the reward eventualities are reversed.

To get reliable results, the stimulus dimensions used in the task should be learned equally well. As in Figure 3 shown visual, tactile and olfactory discriminations in this new device required similar time (F (2.64) = 0.36; p = 0.69) and a similar number of attempts (F (2.64) = 0.059; p = 0.94) to meet the criterion, suggesting that the animals were able to perform simple discriminations independently of the dimension presented.

If a reliable attention sentence has evolved in the test phases of the task, the p developed performance of a normal wild-type mouse should be poorer in the EDS stage compared to earlier and subsequent stages, as in previous studies in rodents and primates 12,13 expelled. In particular, a robust increase in the time and exams required to achieve criteria should be found in the EDS compared to the IDS phases. How Shown in Figure 4 with the 'stuck-in-set' protocol, in our experiment, analysis of the performance of the mice showed a discrimination effect for the number of attempts (F (8168) = 9.23; p <0.0001) and time ( F (8.168) = 8.62; p <0.0001) required to meet criteria. Indeed, mice needed more study and more time to resolve the EDS stage compared to the CD, IDS, IDS2, and EDSRe stages (p <0.05; 4A-B). Similar performance analysis with the "two-dimensional" protocol (Illustration 5) showed a clear differentiation effect for the number of attempts (F (8.72) = 30.66; p <0.005) and the time (F (8.72) = 4.65; p <0.0005) is required to meet criteria. In fact, we show that mice required more studies (p <0.05) and more time (p <0.05) to resolve the EDS compared to CD, IDS, IDS2, and EDSRe (5A-B). No differences in displacement abilities should be noted between mice with different dimensions tested.

In a normal wild-type mouse, learn the first reversal (ie., Cdre) is more difficult than the initial discrimination (ie CD). In agreement as out the 4 and 5, mice needs further study (p <0.05; Figure 4-5a) and more time (p <0.05; Figure 4-5B), complete this phase. In addition, reversing performance should improve cdre to the IDS2Re IDSRe, as we did in our experiment with the two "stuck-in-set" and "two-dimension" protocols. These results further strengthen the evidence of the formation of an attention set by the task.

As the task progresses, the mice should improve their speed in order to respond to more successive stages. Accordingly, the analysis of the latency to respond showed a clear differentiation effect (F (8,200) = 42.59; p <0.0001). In particular, how through representative results in 4C, the latency encountered in the IDS2 stage decreased compared to that in the IDS, CD, and SD stages (p <0.0005). In addition, the latency at the EDS level increased compared to previous IDS2 and IDS2Re and to respond to each other EDSRe levels (p <0.05). Consistent with these results, the analysis of the latency to respond during the "two-dimensional" task also showed a significant effect of discrimination (F (7,63) = 9.98; p <0.0005). How in 5C shown is to make the latency a choice w as during the EDS increased compared to the previous IDS2 and IDS2Re and successive EDSRe (p <0.05). Because the latency to respond, has become an index of decision processing 18 These results were further to suggest that the mice had some processing problems with the new discrimination rule during the EDS. Based on the behavioral performance of wild-type mice (Figure 4-5), we found that the minimum number of sample size (from R-Power analysis) for each experimental group should be 8.


Figure 3. Simple discriminations of light, smell and texture are equivalent.(A) Number of exams and (B) Time is required to achieve the criterion of simple distinctions with only light, smell or texture stimuli. Values ​​represent mean ± SEM whole Numbers 2-4. Data originally published in the "The ultimate intra- and extra-dimensional attention set-shifting task for Mice"19.


Figure 4. Wild-type C57BL6J male mice performance in the 'stuck-in-set' ID / EDOperonTask.(A)Tries, (B) Time (in minutes) and days required to achieve the criterion in the various phases of the ID / ED Operon Task using a 'stuck-in-set' ID / ED paradigm. (C) The time (in seconds) has elapsed between the opening of the separating door and a nasal poke response (latency to respond) during the various stages of the process. A total of 26 mice were tested; 4 mice were excluded because they did not poke reliably to retrieve the food reinforcement during exercise or were unable to complete the entire procedure. A: * p <0.05 compared to CD, IDS, IDS2, IDS2Re and EDSRe; B: * p <0.05 compared to CD, IDS2, IDS2Re and EDSRe. A and B: #p <0.05, ## p <0.005 compared to CD IDSRe and IDS2Re. C: * p <0.05 compared to IDS2, IDS2Re and EDSRe. Note that the mice were able to complete the task in 5-9 days for all experiments in the figures 3-4 specified to complete. Data originally in 'The ultimate intra- and extra-dimensional attention set-shifting task for Mice "19released.Please click here to see a larger version of this figure.

Illustration5. Wild-type C57BL6J male mice performance in the "two-dimension" ID / EDOperon Task.(A)Trials, (B) the time (in minutes) and days required to meet the criterion in the various phases of the ID / ED Operon Achieve task using a two-dimensional paradigm. (C) Time (in seconds) has elapsed between the opening of the separating door and a nasal poke response (latency to respond) during the various stages of the process. A total of 13 mice were tested; 3 mice were excluded because they did not poke reliably to retrieve food reinforcement during exercise or were unable to complete the entire process. A and B: #p <0.05 compared to CD and IDS2Re, * p <0.05 compared to CD, IDS, IDS2, EDSRe. C: * p <0.05 compared to IDS2, IDS2Re and EDSRe. Data originally in 'The ultimate intra- and extra-dimensional attention set-shifting task for Mice "19released.Please click here to enlarge version of this figure.


Figure 6. Timeline of the entire process of the Protocol ID / ED task to test.

stepdescriptionAdditional Commentscredentials
Simple Discrimination (SD)
Link Discrimination (CD) Stimuli differ in two dimensions of perception, such as color and shape for visual stimuli in human tasks or between texture and smell stimuli for rodents
Reversal Learning (cdre - IDSRe - IDS2Re - EDSRe) Two role models within a perceptual dimension have reversed their reinforcement eventualities, so that what was previously correct is then wrong and vice versa) In series reversal learning, the performance improves with the set resolutions. So inversions (ie., Cdre, IDSRe, IDS2Re) not only assess depending on different cortical areas, but also serve 1) to form the cognitive-attention set challenged by the EDS stage, and 2) to prevent unintended aspects of the superstitious attachment stimulus - Lesions of the orbitofrontal cortex in mice (Bissonette et al., 2008) and monkyes impaired reversal learning (Dias et al., 1996)
- FMRT during performance on the reversal learning showed activation of the orbitofrontal cortex (Hampshire and Owen, 2006)
Intradimensional displacement (IDS - IDS2) Novel specimens are introduced, but the same degree is reinforced IDS levels sErve as a crucial internal control (ie., EDS should be more difficult than IDS), and also help to form the cognitive attention sentence Dopamine breakdown in the PFC impaired attention rate formation (Robbins and Roberts, 2007). 6-OHDA damaged monkeys did not show the classical reduction of the reduction in errors from the first (IDS1) to the last (IDS5) discrimination, which should reflect the acquisition of an attention set
Extradimensional Displacement (EDS) 'stuck-in-set' protocol: previously not relevant stimulus dimension is replaced by a new stimulus dimension that is immediately relevant Failure to move to the new relevant dimension cannot be attributed to a previously acquired knowledge of that dimension, as it had not been previously experienced. Failure, hence perseveration reflects on the previously relevant dimension - Lesions of the mPFC have been impaired Show EDS in mice (Bissonette et al., 2008), and mokeys (Dias et al., 1996)
- Frontal lobe patients are impaired in the fixed-in-set state "perseveration", but not in the state "two dimensions" (. Owen et al, 1993)
- Dopamine in the mPFC modulates EDS performance in mice (Papaleo et al, 2008; .. Scheggia et al, 2014) and rats (Tunbridge et al., 2004)
"two dimensions" protocol: reinforcing the previously irrelevant dimension An apparent inattention shift can arise when a subject is able to shift attention from a previously relevant dimension (when it is irrelevant) but is still unable to focus attention on the newly relevant dimension - Lesion of the mPFC in rats (Birrell and Brown, 2000) impaired EDS displacement
- FMRT during performance on the EDS has been shown to activate the ventrolateral PFC (Hampshire and Owen, 2006) 60;

Table 2: Levels of the ID / EDOperontask Description of the stages of the task, including evidence of lesions and pharmacological studies on the role of those involved in the various constructs tested during the task Brain areas ..

Discussion

In this study we introduce a new automated two-chamber ID / ED "Operon" Task for mice that is able to reliably measure cognitive flexibility through reversal learning, attention sentence formation, and shifting. This paradigm, analogous to the WCST and ID / ED tasks, is commonly used in human and non-human primates and overcomes the major limitations of the previous versions for rodents. This Operon Paradigm can be used as a new effective tool for large drug and / or relevant cognitive (dys) functions in mice with high relevance for translational medicine genetic screenings.

This automated task have the following advantages over previously used ID / ED task for rodents: (1) It has less labor intensive procedures than the manual version (e.g. the software regulates all phases of the task, greatly decreasing through the interventions. Investigator); (2) there is no source of subjectivity eliminated in the measured para (for example the experimenter is not required to assess whether the animal actually choice response); (3) This eliminates any possibility that the mice could follow reinforcement-related cues to make an answer (ie the wages are always automatically delivered in the middle of the magazine); (4) it avoids any environmental conditions (e.g. Using mazes and a device of various sizes / materials, using hand made cue stimuli); (5) it allows the manipulation of three different dimensions with a wide range of different stimuli according to the equivalent tasks used in the clinic. Here we only present data from mice, but similar benefits can be expected for rats.

There are critical steps in the task of setting the internal construct-validity parameters to be used to identify attentive areliable-switching performance: i) poorer performance in the EDS compared to previous stages ii) an overall improvement from IDS to IDS2 ; iii) a certain improvement in successive reversal stages, since the more an animal trains in the set resolutions, the better it should be in future internal reversals 20 perform; iv) better performance in the EDSRe compared to the EDS. This novel ID / ED operon task provides all of these functions, in line with previous studies in primates using the CANTAB ID / ED task and in rodents using the manual "digging" version 12,13. Also, each stage of this automated task was divided into an equivalent number of attempts regardless of the relevant / irrelevant dimension (i.e., smell, Texture and light) 19 learned. This showed that all stimuli have similar salience and are suitable for attention set formation and / or switching. Our experiments show that the difficulty in solving the EDS is also highlighted by the increase in latency. Processing time increased for optimal accuracy in the case of severe discrimination 21 to maintain. So, taking into account the latency, to serve as an index of the speed of information processing, decision making and problem solving 18 To respond to the slower latency times during the EDS, a strategy adopted to reflect the difficulty in solving the set-shifting face might face.

We have shown that our new device can effectively use the more "classic" attention-setting-shifting paradigm employing only two dimensions during the test (ie the two-dimensional), or with a fixed-in-set paradigm, which means the use of three dimensions. Depending on the cognitive functions of interest, it is possible to select the most appropriate protocol. Both paradigms were previously used in humans, primates, and rodents 7,12-17 used. However, it is Stucco-in-set The procedure is able to differentiate between the various components of the set-shift and is based on the ore selective measure of the frontal lobes functioning in human patients 7,22. Still a problem that occurs in the two-dimensional Paradigms might arise is that learned irrelevance That could bias the results. Learned irrelevance perseveration refers to the inability to visit and learn about information that was previously not relevant 7 was. This situation can occur in the EDS phase of the two-dimensional Paradigms occur when the person is required to shift attention to the previously irrelevant dimension. In this case it is practically impossible to identify whether an EDS deficit is due to the inability to shift attention from a previously relevant dimension and / or the inability to shift attention to a previously irrelevant dimension. Impairment can then only reflect the active inhibition of the response to a dimension previously rendered irrelevant by its random association with reinforcement feedback. In contrast, the fixed-in-set condition, failure to move to the new relevant dimension cannot be attributed to a previously acquired knowledge about this dimension, since it was not previously experienced. Failure, therefore, reflects perseveration to the previously relevant dimension. In conclusion, even if in normal wild-type mice the "stuck-in-set" and the "two-dimensional" attention-set-shifting paradigms might achieve similar results, we specifically prefer the stuck-in-set perseveration for the Reasons discussed over.

Materials

SurnameCompanyCatalog NumberComments
Plexiglas walls and aluminum floorCustom made(16 x 16 x 16 cm for each chamber)
Plexiglass doorCustom made
PcDell Inc.
MED-PC IV software(Med Associates, St. Albans, VT, USA)custom madeUse an operant code in order to automatically control the presentation of the stimuli and the sequence of the stages
Nose-poke holeMed Associates, St. Albans, VT, USA)ENV-314M
Food magazineMed Associates, St. Albans, VT, USA)ENV-303M
Pellet dispenser for food reinforcementMed Associates, St. Albans, VT, USA)ENV-203-14P
HouselightMed Associates, St. Albans, VT, USA)ENV-315M
Dilution olfactometer(Med Associates, St. Albans, VT, USA)PHM-275
Liquid odorants(Sigma Aldrich, Dorset, UK)(see Table 1)
Mineral oil(Sigma Aldrich, Dorset, UK)M5904
Air pump and vacuum(Med Associates, St. Albans, VT, USA)PHM-280Vacuum is recommended for scents removal at the end of each trial
Light-emitting diodes (LED)High-intensity, transparent gem, 3 mm
Floor textures3x3 cm
Reinforcement pelletsTestDiet5TUL 14mgFor mice

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References

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