JC would like to acknowledge the David Hay Memorial Fund, The University of Melbourne for financial support in writing this manuscript. Funding for this project was provided by an ARC Linkage grant 100200129 (BVB, AJV, CTON).

Ethics statement: Animal experiments were conducted in accordance with the Australian Code for the Care and Use of Animals for Scientific Purposes (2013). Animal ethics approval was obtained from the Animal Ethics Committee, University of Melbourne.&#160;The materials herein are for laboratory experiments only, and not intended for medical or veterinary use.
1. Preparing Electrodes
Note: A three channel transmitter is used for surgical implantation which enables 2 ERG and 1 VEP recording to be conducted simultaneously. The three active and three inactive electrodes need to be pre-fashioned into a ring shape before implantation in order to attach to the eye. For identification purposes, the manufacturer has enclosed active electrodes in half white, half colored plastic sheaths while inactive electrodes are covered in full colored sheaths. The ground electrode (clear plastic sheath) is left unaltered. For all active and inactive electrodes conduct steps 1.1, 1.2, 1.3 and 1.7.
<ol>
	<li>Untwist the double stranded stainless steel electrode with two fine tipped pliers.</li>
	<li>Trim one of the stainless steel strands (approximately 1 cm from the tip), leaving a single longer straight strand remaining to shape the ring electrode.</li>
	<li>Fold the single stainless steel strand back onto itself and twist, forming a smooth ring at the tip of the electrode.</li>
	<li>For the ERG active electrodes fashion this loop ~ 0.2 - 0.5 mm in diameter by twisting the base of the loop (for the purpose described here, shape two active electrodes in this way to record ERG from both eyes), and for the ERG inactive and VEP electrodes make the loop diameter ~ 0.8 mm diameter (in this example, do this for one active VEP electrode and all three inactive electrodes).</li>
	<li>Hook the circular VEP active electrode around a stainless steel screw (diameter 0.7 mm, length 3 mm) so the electrode rests against the screw head.</li>
	<li>Hook the 3 inactive electrodes (2 ERG, 1 VEP) around a second stainless steel screw (diameter 0.7 mm, length 3 mm).</li>
	<li>Pull the plastic sleeve forward over the sharp ends of the two stainless steel strand to reduce irritation.</li>
	<li>Sterilize the telemetry transmitters by soaking in 2% glutaraldehyde for more than 10 hr at approximately 25 &#176;C. Then rinse the transmitter with sterile saline 3 times.</li>
</ol>
2. Transmitter Implantation
<ol>
	<li>Animal Preparation
	<ol>
		<li>Disinfect&#160;the surgical area prior to experimentation by cleaning with 70% ethanol. Autoclave all surgical equipment before use and maintain equipment in chlorhexidine when not in use during surgery. Cover the animal with a surgical drape during surgery to maintain a sterile environment. Ensure all experimenters wear surgical masks, sterile&#160;gloves and gowns.</li>
		<li>Induce anesthesia with 1.5 - 2% isoflurane, at a flow rate of 3 L/min and maintained at 1.5 - 2 % at 2 L/min throughout the surgery. Confirm sufficient depth of anesthesia by absence of a pedal reflex upon pinching the muscle between the toes.</li>
		<li>Shave a 40 mm x 30 mm area over the abdomen from above the groin to the sternum.</li>
		<li>Shave a 30 mm x 20 mm area over the forehead, posterior to the eyes and anterior to the ears.</li>
		<li>Disinfect the two shaved areas. For the forehead area disinfect with 10% povidone-iodine three times (avoid the use of alcohol-based antiseptics for area near the eye, being consistent with the Standard of Practice set out by the Association of Surgical Technologists). Over the abdomen disinfect with 10% povidone iodine and 70% ethanol.</li>
		<li>Apply 1 drop of proxymetacaine to the cornea for additional topical anesthesia.</li>
		<li>Apply 1 drop of carboxymethylcellulose sodium to the cornea to prevent drying of the eyes.</li>
	</ol>
	</li>
	<li>Surgical implantation
	<ol>
		<li>Make a 10 mm incision on the head along the vertical midline between the ears with a surgical scalpel.</li>
		<li>Make a 5 mm incision on the abdomen through the skin layer along the midline below the sternum.</li>
		<li>Tunnel a 5 mm diameter cannula subcutaneously from the abdomen incision to the head incision.</li>
		<li>Feed the electrode wires (3 active and 3 inactive) of the transmitter through the cannula from the abdomen to the head.</li>
		<li>Leave the reference electrode with the transmitter base and cover the electrode tip with aseptic gauze.</li>
		<li>Cover the electrode tips (3 active and 3 inactive) with aseptic gauze.</li>
		<li>Secure the rat&#39;s head to a stereotaxic platform.</li>
		<li>Extend the forehead incision to 30mm in length with surgical scissors.</li>
		<li>Expose surgical area by retracting loose skin with 2 sutures (3 - 0) at ~ 3 and 9 o&#39;clock.</li>
		<li>Scrape off the periosteum overlying the skull using sterilized gauze to expose bregma, lambda and midline sutures.</li>
		<li>Drill two holes through the skull at the VEP active (7 mm ventral to bregma 3 mm lateral to midline) and inactive (5 mm rostral to bregma on the midline) stereotaxic co-ordinates.</li>
		<li>Attach VEP active and inactive electrodes with pre-attached stainless steel screws (diameter 0.7 mm, length 3 mm) to the skull with a small screw-driver to ~ 1 mm in depth into the premade holes. This anchors the screw to the bone without damaging the underlying cortical tissue.</li>
		<li>To implant the ERG active electrodes use an 8 - 0 suture to temporarily retract the upper eyelid.</li>
		<li>Insert a 16 to 21 G cannula subcutaneously from behind the eye through to the superior conjunctival fornix.</li>
		<li>Remove the guiding needle.</li>
		<li>Feed the active electrode through the shortened plastic catheter from the forehead towards the eye. Then remove the plastic catheter.</li>
		<li>Use a temporary suture (8 - 0), which is threaded through the electrode loop, to prevent the electrode from retracting back into the tunnel.</li>
		<li>Make a 0.5 mm incision on the superior conjunctiva at 12 o&#39;clock, 1 mm behind limbus. Use blunt dissection to expose the underlying sclera.</li>
		<li>Implant an 8 - 0 or 9 - 0 suture immediately behind the limbus at half scleral thickness.</li>
		<li>Remove temporary suture from ERG active electrode.</li>
		<li>Anchor the ERG active electrode to the half scleral thickness suture by tying 3 consecutive knots ensuring the tip of the electrode is situated close to the limbus.</li>
		<li>Close the conjunctival flap using 1 to 2 interrupted sutures (8 - 0 to 9 - 0). Ensure that the conjunctiva completely covers the ERG electrode to improve comfort.</li>
		<li>Remove the eyelid retracting suture.</li>
		<li>Repeat the procedure for the contralateral eye.</li>
		<li>Apply cyanoacrylate gel over the skull to secure all stainless screws and electrode wires. Ensure the ERG active electrodes are not pulled too tight before securing to enable eye movements.</li>
		<li>Close the head wound using a non-absorbable 3 - 0 suture.</li>
		<li>Rotate rodent to expose abdominal area. Lengthen the abdominal dermal incision to 40 mm along the linea alba with surgical scissors.</li>
		<li>Make a 35 mm incision through the inner muscle wall to expose the inner abdominal cavity.</li>
		<li>Using two sutures (3 - 0) attach the transmitter body to the animal&#39;s right hand side inner abdominal wall. Avoid contacting the liver.</li>
		<li>Loop the ground electrode and secure in this shape with a suture (3 - 0). Place it free-floating in the abdominal cavity.</li>
		<li>Close the peritoneum using a continuous suture (3 - 0).</li>
		<li>Close the skin incision using interrupted sutures (3 - 0).</li>
	</ol>
	</li>
	<li>Post-operative care
	<ol>
		<li>Monitor the animal until it has regained sufficient consciousness to maintain sternal recumbency. House the animal singly following the surgery.</li>
		<li>Administer carprofen subcutaneously for analgesia (5 mg/kg) once a day for 4 days.</li>
		<li>Add prophylactic oral antibiotics (Enrofloxin, 5 mg/kg) to the drinking water for 7 days post-surgery.</li>
		<li>Apply an anti-inflammatory ointment to skin incision sites to reduce irritation for the first 7 days post-surgery.</li>
	</ol>
	</li>
</ol>
3. Conduct ERG and VEP Recordings in Conscious Rats&#160;
<ol>
	<li>Dark adapt animal for 12 hr prior to ERG and VEP recordings</li>
	<li>Conduct all experimental manipulations under dim red illumination (17.4 cd.m-2, &#955;max = 600 nm)</li>
	<li>Apply topical anesthesia (0.5% proxymetacaine) and dilating (0.5% tropicamide) drops to the cornea.</li>
	<li>Guide the conscious rodent into a custom made, clear restrainer. 
	Note: The length of this plastic tube can be adjusted to accommodate different sized rats with the overall diameter fixed at 60 mm. The front end of the device is tapered to minimize head movement and contains perforations to enable normal breathing. This tapered front allows alignment and stabilization of the rat&#39;s head and eyes to the opening of the Ganzfeld sphere. Note that the rodent has been acclimatized to the restrainer (3 to 5 occasions) prior to surgery.</li>
	<li>Place the rodent in front of the Ganzfeld bowl with the eyes aligned with the opening of the bowl.</li>
	<li>Turn on indwelling transmitter by passing a magnet within ~ 5 cm of the transmitter. Verify that the transmitter is on by checking the LED status light on the receiver base.</li>
	<li>Collect signals over a range of luminous energies (i.e., -5.6 to 1.52 log cd.s.m-2) as described previously21. Briefly, average more signals at the dimmer light levels (~ 80 repeats) and less at the brighter luminous energies (~ 1 repeat). Gradually lengthen the interstimulus interval from 1 to 180 seconds from dimmest to the brightest light level.</li>
	<li>To isolate the ERG rod and cone responses utilize a twin-flash paradigm8. For example, initiate two flashes at 1.52 log cd.s.m-2 with a 500 msec inter-stimulus interval in-between.</li>
	<li>To record VEP signals, average 20 repeats at the brighter luminous energies (i.e., 1.52 log cd.s.m-2, 5 sec inter-stimulus interval).</li>
	<li>To evaluate implant stability, which is assessed by signal variability over time, conduct ERG and VEP recordings 7, 10, 14, 21 and 28 days post-surgery.</li>
	<li>Following experimental period, euthanize rats via intracardial injection of pentobarbiturate (1.5 ml/kg) after ketamine:xylazine anesthesia (12:1 mg/kg).</li>
</ol>

<ol>
	<li>Frishman, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Origins of the Electroretinogram. , (2006).</li><li>Granit, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+components+of+the+retinal+action+potential+in+mammals+and+their+relation+to+the+discharge+in+the+optic+nerve.">The components of the retinal action potential in mammals and their relation to the discharge in the optic nerve.</a> J Physiol. 77, 207-239 (1933).</li><li>Brown, K. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+eclectroretinogram:+its+components+and+their+origins.">The eclectroretinogram: its components and their origins.</a> Vision Res. 8, 633-677 (1968).</li><li>Brown, K. T., Murakami, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biphasic+Form+of+the+Early+Receptor+Potential+of+the+Monkey+Retina.">Biphasic Form of the Early Receptor Potential of the Monkey Retina.</a> Nature. 204, 739-740 (1964).</li><li>Kline, R. P., Ripps, H., Dowling, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+b-wave+currents+in+the+skate+retina.">Generation of b-wave currents in the skate retina.</a> Proc Natl Acad Sci U S A. 75, 5727-5731 (1978).</li><li>Krasowski, M. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Propofol+and+other+intravenous+anesthetics+have+sites+of+action+on+the+gamma-aminobutyric+acid+type+A+receptor+distinct+from+that+for+isoflurane.">Propofol and other intravenous anesthetics have sites of action on the gamma-aminobutyric acid type A receptor distinct from that for isoflurane.</a> Mol Pharmacol. 53, 530-538 (1998).</li><li>Stockton, R. A., Slaughter, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B-wave+of+the+electroretinogram.+A+reflection+of+ON+bipolar+cell+activity.">B-wave of the electroretinogram. A reflection of ON bipolar cell activity.</a> J Gen Physiol. 93, 101-122 (1989).</li><li>Nixon, P. J., Bui, B. V., Armitage, J. A., Vingrys, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+contribution+of+cone+responses+to+rat+electroretinograms.">The contribution of cone responses to rat electroretinograms.</a> Clin Experiment Ophthalmol. 29, 193-196 (2001).</li><li>Weinstein, G. W., Odom, J. V., Cavender, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visually+evoked+potentials+and+electroretinography+in+neurologic+evaluation.">Visually evoked potentials and electroretinography in neurologic evaluation.</a> Neurol Clin. 9, 225-242 (1991).</li><li>Sand, T., Kvaloy, M. B., Wader, T., Hovdal, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evoked+potential+tests+in+clinical+diagnosis.">Evoked potential tests in clinical diagnosis.</a> Tidsskr Nor Laegeforen. 133, 960-965 (2013).</li><li>Brankack, J., Schober, W., Klingberg, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Different+laminar+distribution+of+flash+evoked+potentials+in+cortical+areas+17+and+18+b+of+freely+moving+rats.">Different laminar distribution of flash evoked potentials in cortical areas 17 and 18 b of freely moving rats.</a> J Hirnforsch. 31, 525-533 (1990).</li><li>Creel, D., Dustman, R. E., Beck, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intensity+of+flash+illumination+and+the+visually+evoked+potential+of+rats,+guinea+pigs+and+cats.">Intensity of flash illumination and the visually evoked potential of rats, guinea pigs and cats.</a> Vision Res. 14, 725-729 (1974).</li><li>Herr, D. W., Boyes, W. K., Dyer, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+flash-evoked+potential+peak+N160+amplitude:+modulation+by+relative+flash+intensity.">Rat flash-evoked potential peak N160 amplitude: modulation by relative flash intensity.</a> Physiol Behav. 49, 355-365 (1991).</li><li>Guarino, I., Loizzo, S., Lopez, L., Fadda, A., Loizzo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+chronic+implant+to+record+electroretinogram,+visual+evoked+potentials+and+oscillatory+potentials+in+awake,+freely+moving+rats+for+pharmacological+studies.">A chronic implant to record electroretinogram, visual evoked potentials and oscillatory potentials in awake, freely moving rats for pharmacological studies.</a> Neural Plast. 11, 241-250 (2004).</li><li>Szabo-Salfay, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+electroretinogram+and+visual+evoked+potential+of+freely+moving+rats.">The electroretinogram and visual evoked potential of freely moving rats.</a> Brain Res Bull. 56, 7-14 (2001).</li><li>Valjakka, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+reflection+of+retinal+light+response+information+onto+the+superior+colliculus+in+the+rat.">The reflection of retinal light response information onto the superior colliculus in the rat.</a> Graefes Arch Clin Exp Ophthalmol. 245, 1199-1210 (2007).</li><li>Lapray, D., Bergeler, J., Dupont, E., Thews, O., Luhmann, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+miniature+telemetric+system+for+recording+EEG+activity+in+freely+moving+rats.">A novel miniature telemetric system for recording EEG activity in freely moving rats.</a> J Neurosci Methods. 168, 119-126 (2008).</li><li>Lim, K., Burke, S. L., Armitage, J. A., Head, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+blood+pressure+and+sympathetic+activity+of+rabbits+in+their+home+cage+and+the+laboratory+environment.">Comparison of blood pressure and sympathetic activity of rabbits in their home cage and the laboratory environment.</a> Exp Physiol. 97, 1263-1271 (2012).</li><li>Nguyen, C. T., Brain, P., Ivarsson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparing+activity+analyses+for+improved+accuracy+and+sensitivity+of+drug+detection.">Comparing activity analyses for improved accuracy and sensitivity of drug detection.</a> J Neurosci Methods. 204, 374-378 (2012).</li><li>Ivarsson, M., Paterson, L. M., Hutson, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antidepressants+and+REM+sleep+in+Wistar-Kyoto+and+Sprague-Dawley+rats.">Antidepressants and REM sleep in Wistar-Kyoto and Sprague-Dawley rats.</a> Eur J Pharmacol. 522, 63-71 (2005).</li><li>He, Z., Bui, B. V., Vingrys, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+rate+of+functional+recovery+from+acute+IOP+elevation.">The rate of functional recovery from acute IOP elevation.</a> Invest Ophthalmol Vis Sci. 47, 4872-4880 (2006).</li><li>Lamb, T. D., Pugh, E. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+quantitative+account+of+the+activation+steps+involved+in+phototransduction+in+amphibian+photoreceptors.">A quantitative account of the activation steps involved in phototransduction in amphibian photoreceptors.</a> J Physiol. 449, 719-758 (1992).</li><li>Hood, D. C., Birch, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rod+phototransduction+in+retinitis+pigmentosa:+estimation+and+interpretation+of+parameters+derived+from+the+rod+a-wave.">Rod phototransduction in retinitis pigmentosa: estimation and interpretation of parameters derived from the rod a-wave.</a> Invest Ophthalmol Vis Sci. 35, 2948-2961 (1994).</li><li>Charng, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conscious+wireless+electroretinogram+and+visual+evoked+potentials+in+rats.">Conscious wireless electroretinogram and visual evoked potentials in rats.</a> PLoS Onez. 8, e74172 (2013).</li><li>Galambos, R., Szabo-Salfay, O., Szatmari, E., Szilagyi, N., Juhasz, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sleep+modifies+retinal+ganglion+cell+responses+in+the+normal+rat.">Sleep modifies retinal ganglion cell responses in the normal rat.</a> Proc Natl Acad Sci U S A. 98, 2083-2088 (2001).</li><li>Meeren, H. K., Van Luijtelaar, E. L., Coenen, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortical+and+thalamic+visual+evoked+potentials+during+sleep-wake+states+and+spike-wave+discharges+in+the+rat.">Cortical and thalamic visual evoked potentials during sleep-wake states and spike-wave discharges in the rat.</a> Electroencephalogr Clin Neurophysiol. 108, 306-319 (1998).</li><li>Nair, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+common+anesthetics+on+eye+movement+and+electroretinogram.">Effects of common anesthetics on eye movement and electroretinogram.</a> Doc Ophthalmol. 122, 163-176 (2011).</li><li>Amouzadeh, H. R., Sangiah, S., Qualls, C. W., Cowell, R. L., Mauromoustakos, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xylazine-induced+pulmonary+edema+in+rats.">Xylazine-induced pulmonary edema in rats.</a> Toxicol Appl Pharmacol. 108, 417-427 (1991).</li><li>Charng, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+electrophysiology+is+a+viable+preclinical+biomarker+for+drug+penetrance+into+the+central+nervous+system.">Retinal electrophysiology is a viable preclinical biomarker for drug penetrance into the central nervous system.</a> J Ophthalmol. , (2016).</li></ol>

RG and RF are employees to the commercial funder of this research (Pfizer Neusentis and Pfizer Global Research). MI was an employee of Pfizer Global Research during this research and is currently an employee of Proteostasis Therapeutics (Cambridge, USA).

Due to the minimally invasive nature of visual electrophysiology, ERG and VEP recordings in human patients are conducted under conscious conditions and only require the use of topical anesthetics for electrode placement. In contrast, visual electrophysiology in animal models is conventionally conducted under general anesthesia to enable stable electrode placement by eliminating voluntary eye and body movements. However, commonly used general anesthetics alter the ERG and VEP responses as shown by our previous publication...

The ERG and VEP are minimally invasive in vivo tools to assess the integrity of retinal and visual pathways respectively in both the laboratory and clinic. The full-field ERG yields a characteristic waveform which can be broken down into different components, with each element representing different cell classes of the retinal pathway1,2. The classic full-field ERG waveform consists of an initial negative slope (a-wave), which has been shown to represent photoreceptor activity post light exposure2-4. The a-wave is followed by a substantial positive waveform (b-wave) which reflects electrical activity of middle retina, predominantly the ON-bipolar cells5-7. Furthermore, one can vary luminous energy and inter-stimulus-interval to isolate cone from rod responses8.
The flash VEP represents electrical potentials of the visual cortex and brain stem in response to retinal light stimulation9,10. This waveform can be broken down into early and late components, with the early component reflecting activity of neurons of the retino-geniculo-striate pathway11-13 and the late component representing cortical processing performed in various V1 laminae in rats11,13. Therefore simultaneous measurement of the ERG and VEP returns comprehensive assessment of the structures involved in the visual pathway.
Currently, in order to record electrophysiology in animals, anesthesia is employed to enable stable placement of electrodes. There have been attempts to measure ERG and VEP in conscious rats14-16 but these studies employed a wired setup, which can be cumbersome and may lead to animal stress by restricting animal movement and natural behavior17. With recent advances in wireless technology including improved miniaturization and battery life, it is now possible to implement a telemetry approach for ERG and VEP recording, decreasing the stress associated with wired recordings and improving long term viability. Fully internalized stable implantations of telemetry probes have proven to be successful for chronic monitoring of temperature, blood pressure18, activity19 as well as electroencephalography20. Such advances in technology will also assist with repeatability and stability of conscious recordings, increasing the platform&#39;s utility for chronic studies.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Bioamplifier</td>
			<td>ADInstruments</td>
			<td>ML 135</td>
			<td>Amplifies ERG and VEP signals</td>
		</tr>
		<tr>
			<td>Carboxymethylcellulose sodium 1.0%</td>
			<td>Allergan</td>
			<td>CAS 0009000-11-7</td>
			<td>Maintain corneal hydration during surgery</td>
		</tr>
		<tr>
			<td>Carprofen 0.5%</td>
			<td>Pfizer Animal Health Group</td>
			<td>CAS 53716-49-7</td>
			<td>Post-surgery analgesia, given with injectable saline for fluid replenishment</td>
		</tr>
		<tr>
			<td>Chlorhexadine 0.5%</td>
			<td>Orion Laboratories</td>
			<td>27411, 80085</td>
			<td>Disinfection of surgical instrument</td>
		</tr>
		<tr>
			<td>Cyanoacrylate gel activator</td>
			<td>RS components</td>
			<td>473-439</td>
			<td>Quickly dries cyanoacrylate gel</td>
		</tr>
		<tr>
			<td>Cyanocrylate gel&#160;</td>
			<td>RS components</td>
			<td>473-423</td>
			<td>Fix stainless screws to skull</td>
		</tr>
		<tr>
			<td>Dental burr</td>
			<td>Storz Instruments, Bausch and Lomb</td>
			<td>E0824A</td>
			<td>Miniature drill head of ~0.7mm diameter for making a small hole in the skull over each hemisphere to implant VEP screws</td>
		</tr>
		<tr>
			<td>Drill</td>
			<td>Bosch</td>
			<td>Dremel 300 series</td>
			<td>Automatic drill for trepanning</td>
		</tr>
		<tr>
			<td>Enrofloxin</td>
			<td>Troy Laboratories</td>
			<td></td>
			<td>Prophylactic antibiotic post surgey</td>
		</tr>
		<tr>
			<td>Ganzfeld integrating sphere</td>
			<td>Photometric Solutions International</td>
			<td></td>
			<td>Custom designed light stimulator: 36 mm diameter, 13 cm aperture size</td>
		</tr>
		<tr>
			<td>Gauze swabs</td>
			<td>Multigate Medical Products Pty Ltd</td>
			<td>57-100B</td>
			<td>Dries surgical incision and exposed skull surface during surgery</td>
		</tr>
		<tr>
			<td>Isoflurane 99.9%</td>
			<td>Abbott Australasia Pty Ltd</td>
			<td>CAS 26675-46-7</td>
			<td>Proprietory Name: Isoflo(TM) Inhalation anaaesthetic. Pharmaceutical-grade inhalation anesthetic mixed with oxygen gas for VEP electrode implant surgery</td>
		</tr>
		<tr>
			<td>Kenacomb ointment</td>
			<td>Aspen Pharma Pty Ltd</td>
			<td></td>
			<td>To reduce skin irritation and itching after surgery</td>
		</tr>
		<tr>
			<td>Luxeon LEDs</td>
			<td>Phillips Lighting Co.</td>
			<td></td>
			<td>For light stimulation, twenty 5 watt and one 1 watt LEDs, controlled by Scope software</td>
		</tr>
		<tr>
			<td>Needle (macrosurgery)</td>
			<td>World Precision Instruments</td>
			<td>501959</td>
			<td>for suturing abdominal and head surgery, used with 3-0 suture, eye needle, cutting edge 5/16 circle Size 1, 15mm</td>
		</tr>
		<tr>
			<td>Needle holder (macrosurgery)</td>
			<td>World Precision Instruments</td>
			<td>500224</td>
			<td>To hold needle during abdominal and head surgery</td>
		</tr>
		<tr>
			<td>Needle holder (microsurgery)</td>
			<td>World Precision Instruments</td>
			<td>555419NT</td>
			<td>To hold needle during ocular surgery</td>
		</tr>
		<tr>
			<td>Optiva catheter</td>
			<td>Smiths Medical International LTD</td>
			<td>16 or 21 G</td>
			<td>Guide corneal active electrodes from skull to conjunctiva</td>
		</tr>
		<tr>
			<td>Povidone iodine 10%</td>
			<td>Sanofi-Aventis</td>
			<td>CAS 25655-41-8</td>
			<td>Proprietory name: Betadine, Antiseptic to prepare the shaved skin for surgery 10%, 500 mL</td>
		</tr>
		<tr>
			<td>Powerlab data acquisition system</td>
			<td>ADInstruments</td>
			<td>ML 785</td>
			<td>Acquire signal from telemetry transmitter, paired to telemetry data converter</td>
		</tr>
		<tr>
			<td>Proxymetacaine 0.5%</td>
			<td>Alcon Laboratories&#160;</td>
			<td>CAS 5875-06-9</td>
			<td>Topical ocular analgesia</td>
		</tr>
		<tr>
			<td>Restrainer</td>
			<td>cutom made</td>
			<td></td>
			<td>Front of the restrainer is tapered to minimize head movement, length can be adjusted to accommodate different rat length, overall diameter is 60 mm.&#160;</td>
		</tr>
		<tr>
			<td>Scapel blade</td>
			<td>R.G. Medical Supplies</td>
			<td>SNSM0206</td>
			<td>For surgical incision</td>
		</tr>
		<tr>
			<td>Scissors (macrosurgery)</td>
			<td>World Precision Instruments</td>
			<td>501225</td>
			<td>for cutting tissue on the abodmen and forhead</td>
		</tr>
		<tr>
			<td>Scissors (microsurgery)</td>
			<td>World Precision Instruments</td>
			<td>501232</td>
			<td>To dissect the conjunctiva for electrode attachment</td>
		</tr>
		<tr>
			<td>Scope Software</td>
			<td>ADInstruments</td>
			<td>version 3.7.6</td>
			<td>Simultaneously triggers the stimulus via the ADI Powerlab system and collects data</td>
		</tr>
		<tr>
			<td>Shaver</td>
			<td>Oster</td>
			<td>Golden A5</td>
			<td>Shave fur from surgical areas</td>
		</tr>
		<tr>
			<td>Stainless streel screws&#160;</td>
			<td>MicroFasteners</td>
			<td>L001.003CS304</td>
			<td>0.7 mm shaft diameter, 3 mm in length&#160;</td>
		</tr>
		<tr>
			<td>Stereotaxic frame</td>
			<td>David Kopf</td>
			<td>Model 900</td>
			<td>A small animal stereotaxic instrument for locating the implantation landmarks on the skull</td>
		</tr>
		<tr>
			<td>Surgical drape</td>
			<td>Vital Medical Supplies</td>
			<td>GM29-612EE</td>
			<td>Ensure sterile enviornment during surgery</td>
		</tr>
		<tr>
			<td>Suture (macrosurgery)</td>
			<td>Ninbo medical needles</td>
			<td>3-0</td>
			<td>for suturing abdominal and head surgery, sterile silk braided, 60cm</td>
		</tr>
		<tr>
			<td>Suture needle (microsurgery)</td>
			<td>Ninbo medical needles</td>
			<td>8-0 or 9-0</td>
			<td>for ocular surgery including, suturing electrode to sclera and closing conjunctival wound, nylon suture, 3/8 circle 1&#215;5, 30cm</td>
		</tr>
		<tr>
			<td>Telemetry data converter&#160;</td>
			<td>DataSciences International</td>
			<td>R08</td>
			<td>allows telemetry signal to interface with data collection software</td>
		</tr>
		<tr>
			<td>Telemetry Data Exchange Matrix</td>
			<td>DataSciences International</td>
			<td></td>
			<td>Gathers data from transmitters, pair with receiver</td>
		</tr>
		<tr>
			<td>Telemetry data receiver</td>
			<td>DataSciences International</td>
			<td>RPC-1</td>
			<td>Receives telemetry data from transmitter</td>
		</tr>
		<tr>
			<td>Telemetry transmitter</td>
			<td>DataSciences International</td>
			<td>F50-EEE</td>
			<td>3 channel telemetry transmitter</td>
		</tr>
		<tr>
			<td>Tropicamide 0.5%</td>
			<td>Alcon Laboratories&#160;</td>
			<td></td>
			<td>Iris dilation</td>
		</tr>
		<tr>
			<td>Tweezers (macrosurgery)</td>
			<td>World Precision Instruments</td>
			<td>500092</td>
			<td>Manipulate tissues during abdominal and head surgery</td>
		</tr>
		<tr>
			<td>Tweezers (microsurgery)</td>
			<td>World Precision Instruments</td>
			<td>500342</td>
			<td>Manipulate tissues during ocular surgery</td>
		</tr>
	</tbody>
</table>

implantation and recording of wireless electroretinogram and visual evoked potential in conscious rats

The full-field electroretinogram (ERG) and visual evoked potential (VEP) are useful tools to assess retinal and visual pathway integrity in both laboratory and clinical settings. Currently, preclinical ERG and VEP measurements are performed with anesthesia to ensure stable electrode placements. However, the very presence of anesthesia has been shown to contaminate normal physiological responses. To overcome these anesthesia confounds, we develop a novel platform to assay ERG and VEP in conscious rats. Electrodes are surgically implanted sub-conjunctivally on the eye to assay the ERG and epidurally over the visual cortex to measure the VEP. A range of amplitude and sensitivity/timing parameters are assayed for both the ERG and VEP at increasing luminous energies. The ERG and VEP signals are shown to be stable and repeatable for at least 4 weeks post surgical implantation. This ability to record ERG and VEP signals without anesthesia confounds in the preclinical setting should provide superior translation to clinical data.

The photoreceptor response is analyzed by fitting a delayed Gaussian to the leading edge of the initial descending limb of the ERG response at the top 2 luminous energies (1.20, 1.52 log c.s.m-2) for each animal, based on the model of Lamb and Pugh22, formulated by Hood and Birch23. This formula returns an amplitude and a sensitivity parameter, (Figure 1C and 1D, respectively). A hyperbolic function was fitted to the lumin...

Watch this Scientific Journal Video about Implantation and Recording of Wireless Electroretinogram and Visual Evoked Potential in Conscious Rats at JoVE.com

Implantation and Recording of Wireless Electroretinogram and Visual Evoked Potential in Conscious Rats

We show surgical implantation and Recording procedures to measure visual electrophysiological signals from the eye (electroretinogram) and brain (visual evoked potential) in conscious rats, which is more analogous to the human condition where recordings are conducted without anesthesia confounds.

The full-field electroretinogram (ERG) and visual evoked potential (VEP) are useful tools to assess retinal and visual pathway integrity in both ...

implantation-recording-wireless-electroretinogram-visual-evoked

Research

JoVE Journal

Behavior

8.6K Views.  University of Melbourne. We show surgical implantation and Recording procedures to measure visual electrophysiological signals from the eye (electroretinogram) and brain (visual evoked potential) in conscious rats, which is more analogous to the human condition where recordings are conducted without anesthesia confounds.

Video: Implantation and Recording of Wireless Electroretinogram and Visual Evoked Potential in Conscious Rats

The Successive Alleys Test of Anxiety in Mice and Rats

The plus-maze was derived from the early work of Montgomery. He observed that rats tended to avoid the open arms of a maze, preferring the enclosed ones. Handley, Mithani and File et al. performed the first studies on the plus-maze design we use today, and in 1987 Lister published a design for use with mice. 
Time spent on, and entries into, the open arms are an index of anxiety; the lower these indices, the more anxious the mouse is. Alternatively, a mouse that spends most of its time in the closed arms is classed as anxious. 
One of the problems of the plus-maze is that, while time spent on, and entries into, the open arms is a fairly unambiguous measure of anxiety, time in the central area is more difficult to interpret, although time spent here has been classified as &#x201C;decision making&#x201D;. In many tests central area time is a considerable part of the total test time.
Shepherd et al. produced an ingenious design to eliminate the central area, which they called the &#x201C;zero maze&#x201D;. However, although used by several groups, it has never been as widely adopted as the plus-maze. 
In the present article I describe a modification of the plus-maze design that not only eliminates the central area but also incorporates elements from other anxiety tests, such as the light-dark box and emergence tests. It is a linear series of four alleys, each having increasing anxiogenic properties. It has given similar results to the plus-maze in general. Although it may not be more sensitive than the plus-maze (more data is needed before a firm conclusion can be reached on this point), it provides a useful confirmation of plus-maze results which would be useful when, for example, only a single example of a mutant mouse was available, as, for example, in ENU-based mutagenesis programs.

The plus-maze measures anxiety-like behaviour in rodents. There are two opposite closed and two opposite open arms; anxious rodents avoid the open arms. The central area is neither completely open nor closed, so time spent here is ambiguous and difficult to interpret. Here a modification of the plus-maze protocol eliminating this area is described.

The plus-maze was derived from the early work of Montgomery. He observed that rats tended to avoid the open arms of a maze, preferring the enclosed ones.  ...

Automated Visual Cognitive Tasks for Recording Neural Activity Using a Floor Projection Maze

Neuropsychological tasks used in primates to investigate mechanisms of learning and memory are typically visually guided cognitive tasks. We have developed visual cognitive tasks for rats using the Floor Projection Maze1,2&#160;that are optimized for visual abilities of rats permitting stronger comparisons of experimental findings with other species.
In order to investigate neural correlates of learning and memory, we have integrated electrophysiological recordings into fully automated cognitive tasks on the Floor Projection Maze1,2. Behavioral software interfaced with an animal tracking system allows monitoring of the animal's behavior with precise control of image presentation and reward contingencies for better trained animals. Integration with an in vivo electrophysiological recording system enables examination of behavioral correlates of neural activity at selected epochs of a given cognitive task.
We describe protocols for a model system that combines automated visual presentation of information to rodents and intracranial reward with electrophysiological approaches. Our model system offers a sophisticated set of tools as a framework for other cognitive tasks to better isolate and identify specific mechanisms contributing to particular cognitive processes.

We describe protocols for training rats for chronic electrophysiological recordings in fully automated cognitive tasks on a Floor Projection Maze.

Neuropsychological tasks used in primates to investigate mechanisms of learning and memory are typically visually guided cognitive tasks. We have ...

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are deliberately planned, while others spontaneously occur below conscious awareness. The deliberate component of this dichotomy has been studied extensively in several contexts, while the spontaneous component remains largely under-explored. Moreover, how perceptual processes modulate these movement classes is still unclear. In particular, a currently debated issue is whether the visuomotor system is governed by the spatial percept produced by a visual illusion or whether it is not affected by the illusion and is governed instead by the veridical percept. Bistable percepts such as 3D depth inversion illusions (DIIs) provide an excellent context to study such interactions and balance, particularly when used in combination with reach-to-grasp movements. In this study, a methodology is developed that uses a DII to clarify the role of top-down processes on motor action, particularly exploring how reaches toward a target on a DII are affected in both deliberate and spontaneous movement domains.

It is unclear how top-down signals from the ventral visual stream affect movement. We developed a paradigm to test motor behavior towards a target on a 3D depth inversion illusion. Significant differences are reported in both deliberate, goal-directed movements and automatic actions under illusory and veridical viewing conditions.

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are ...

The Modified Hole Board - Measuring Behavior, Cognition and Social Interaction in Mice and Rats

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure multiple dimensions of unconditioned behavior in small laboratory mammals (e.g., mice, rats, tree shrews and small primates). This paradigm is a valuable alternative for the use of a behavioral test battery, since a broad behavioral spectrum of an animal&#8217;s behavioral profile can be investigated in one single test.
The apparatus consists of a box, representing the &#8216;protected&#8217; area, separated from a group compartment. A board, on which small cylinders are staggered in three lines, is placed in the center of the box, representing the &#8216;unprotected&#8217; area of the set-up. The cognitive abilities of the animals can be measured by baiting some cylinders on the board and measuring the working and reference memory. Other unconditioned behavior, such as activity-related-, anxiety-related- and social behavior, can be observed using this paradigm. Behavioral flexibility and the ability to habituate to a novel environment can additionally be observed by subjecting the animals to multiple trials in the mHB, revealing insight into the animals&#8217; adaptive capacities.
Due to testing order effects in a behavioral test battery, na&#239;ve animals should be used for each individual experiment. By testing multiple behavioral dimensions in a single paradigm and thereby circumventing this issue, the number of experimental animals used is reduced. Furthermore, by avoiding social isolation during testing and without the need to food deprive the animals, the mHB represents a behavioral test system, inducing if any, very low amount of stress.

This protocol describes the modified hole board, which is a behavioral test set-up that comprises the characteristics of an open field and a traditional hole board. This set-up enables the differential analysis of unconditioned behavior of small laboratory mammals as well as the analysis of cognitive abilities.

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure ...

Conscious and Non-conscious Representations of Emotional Faces in Asperger's Syndrome

Several neuroimaging studies have suggested that the low spatial frequency content in an emotional face mainly activates the amygdala, pulvinar, and superior colliculus especially with fearful faces1-3. These regions constitute the limbic structure in non-conscious perception of emotions and modulate cortical activity either directly or indirectly2. In contrast, the conscious representation of emotions is more pronounced in the anterior cingulate, prefrontal cortex, and somatosensory cortex for directing voluntary attention to details in faces3,4. Asperger&#39;s syndrome (AS)5,6 represents an atypical mental disturbance that affects sensory, affective and communicative abilities, without interfering with normal linguistic skills and intellectual ability. Several studies have found that functional deficits in the neural circuitry important for facial emotion recognition can partly explain social communication failure in patients with AS7-9. In order to clarify the interplay between conscious and non-conscious representations of emotional faces in AS, an EEG experimental protocol is designed with two tasks involving emotionality evaluation of either photograph or line-drawing faces. A pilot study is introduced for selecting face stimuli that minimize the differences in reaction times and scores assigned to facial emotions between the pretested patients with AS and IQ/gender-matched healthy controls. Information from the pretested patients was used to develop the scoring system used for the emotionality evaluation. Research into facial emotions and visual stimuli with different spatial frequency contents has reached discrepant findings depending on the demographic characteristics of participants and task demands2. The experimental protocol is intended to clarify deficits in patients with AS in processing emotional faces when compared with healthy controls by controlling for factors unrelated to recognition of facial emotions, such as task difficulty, IQ and gender.

An EEG experimental protocol is designed to clarify the interplay between conscious and non-conscious representations of emotional faces in patients with Asperger&#39;s syndrome. The technique suggests that patients with Asperger&#39;s syndrome have deficits in non-conscious representation of emotional faces, but have comparable performance in conscious representation with healthy controls.

Several neuroimaging studies have suggested that the low spatial frequency content in an emotional face mainly activates the amygdala, pulvinar, and ...

Manipulation of Epileptiform Electrocorticograms (ECoGs) and Sleep in Rats and Mice by Acupuncture

Ancient Chinese literature has documented that acupuncture possesses efficient therapeutic effects on epilepsy and insomnia. There is, however, little research to reveal the possible mechanisms behind these effects. To investigate the effect of acupuncture on epilepsy and sleep, several issues need to be addressed. The first is to identify the acupoints, which correspond between humans, rats, and mice. Furthermore, the depth of insertion of the acupuncture needle, the degree of needle twist in manual needle acupuncture, and the stimulation parameters for electroacupuncture (EA) need to be determined. To evaluate the effects of acupuncture on epilepsy and sleep, a feasible model of epilepsy in rodents is required. We administer pilocarpine into the left central nucleus of the amygdala (CeA) to simulate focal temporal lobe epilepsy (TLE) in rats. Intraperitoneal (IP) injection of pilocarpine induces generalized epilepsy and status epilepticus (SE) in rats. Five IP injections of pentylenetetrazol (PTZ) with a one-day interval between each injection successfully induces spontaneous generalized epilepsy in mice. Recordings of electrocorticograms (ECoGs), electromyograms (EMGs), brain temperature, and locomotor activity are used for sleep analysis in rats, while ECoGs, EMGs, and locomotor activity are employed for sleep analysis in mice. ECoG electrodes are implanted into the frontal, parietal, and contralateral occipital cortices, and a thermistor is implanted above the cerebral cortex by stereotactic surgery. EMG electrodes are implanted into the neck muscles, and an infrared detector determines locomotor activity. The criteria for categorizing vigilance stages, including wakefulness, rapid eye movement (REM) sleep, and non-REM (NREM) sleep are based on information from ECoGs, EMGs, brain temperature, and locomotor activity. Detailed classification criteria are stated in the text.

Manipulation of Epileptiform Electrocorticograms ECoGs and Sleep in Rats and Mice by Acupuncture

This paper demonstrates the performance of acupuncture, epilepsy models, and the analysis of sleep in rodents. The acupuncture procedure and the identification of acupoints are described. Pilocarpine or pentylenetetrazol (PTZ) is used to induce epilepsy. Electrocorticogram (ECoG), electromyogram (EMG), brain temperature, and locomotor activity recordings are employed for sleep analysis.

Ancient Chinese literature has documented that acupuncture possesses efficient therapeutic effects on epilepsy and insomnia. There is, however, little ...

A Wireless, Bidirectional Interface for In Vivo Recording and Stimulation of Neural Activity in Freely Behaving Rats

In vivo electrophysiology is a powerful technique to investigate the relationship between brain activity and behavior at a millisecond and micrometer scale. However, current methods mostly rely on tethered cable recordings or only use unidirectional systems, allowing either recording or stimulation of neural activity, but not at the same time or same target. Here, a new wireless, bidirectional device for simultaneous multichannel recording and stimulation of neural activity in freely behaving rats is described. The system operates through a single portable head stage that both transmits recorded activity and can be targeted in real-time for brain stimulation using a telemetry-based multichannel software. The head stage is equipped with a preamplifier and a rechargeable battery, allowing stable long-term recordings or stimulation for up to 1 h. Importantly, the head stage is compact, weighs 12 g (including battery) and thus has minimal impact on the animal&#180;s behavioral repertoire, making the method applicable to a broad set of behavioral tasks. Moreover, the method has the major advantage that the effect of brain stimulation on neural activity and behavior can be measured simultaneously, providing a tool to assess the causal relationships between specific brain activation patterns and behavior. This feature makes the method particularly valuable for the field of deep brain stimulation, allowing precise assessment, monitoring, and adjustment of stimulation parameters during long-term behavioral experiments. The applicability of the system has been validated using the inferior colliculus as a model structure.

A Wireless, Bidirectional Interface for In Vivo Recording and Stimulation of Neural Activity in Freely Behaving Rats

A wireless, bidirectional system for multi-channel neural recordings and stimulation in freely behaving rats is introduced. The system is light and compact, thus having minimal impact on the animal&#180;s behavioral repertoire. Moreover, this bidirectional system provides a sophisticated tool to assess causal relationships between brain activation patterns and behavior.

In vivo electrophysiology is a powerful technique to investigate the relationship between brain activity and behavior at a millisecond and micrometer ...

Using Electroencephalography Measurements and High-quality Video Recording for Analyzing Visual Perception of Media Content

This article explores a method to detect differences in visual perception in humans. The method used is based on the psychological (or "cognitive") function of eyeblinks. Participants' eyeblinks are detected and acquired while watching videos specifically created for the investigation. The detection and acquisition of eyeblinks are carried out with the help of a 20-channel electroencephalographic (EEG) wireless device. The international 10-20 system for electrode placement is followed. A high-definition (HD) video camera is used to record participants' facial expressions, for contrast purposes. Instead of using pre-existing media content, purpose-made video content has been created following specific criteria of interest for this investigation, with stimuli enabling researchers to manage the precise parameters of interest. Otherwise, results could be contaminated with uncontrolled variables. The synchronization of the presentation of video stimuli with EEG recordings needs to be done in milliseconds. Analysis of collected data is performed with robust software for working with big matrices. Statistically significant differences in eyeblink rate related to media professionalization and editing style are found with the reported experimental procedures.

We present detection, acquisition, and analysis of eyeblink rates while watching media content.

This article explores a method to detect differences in visual perception in humans. The method used is based on the psychological (or "cognitive") ...

Eye Tracking During Visually Situated Language Comprehension: Flexibility and Limitations in Uncovering Visual Context Effects

The present work is a description and an assessment of a methodology designed to quantify different aspects of the interaction between language processing and the perception of the visual world. The recording of eye-gaze patterns has provided good evidence for the contribution of both the visual context and linguistic/world knowledge to language comprehension. Initial research assessed object-context effects to test&#160;theories of modularity in language processing. In the introduction, we describe how subsequent investigations have taken the role of the wider visual context in language processing as a research topic in its own right, asking questions such as how our visual perception of events and of speakers contributes to&#160;comprehension informed by&#160;comprehenders&#39; experience. Among the examined aspects of the visual context are actions, events, a speaker&#39;s gaze, and emotional facial expressions, as well as spatial object configurations. Following an overview of the eye-tracking method and its different applications, we list the key steps of the methodology in the protocol, illustrating how to successfully use it to study visually-situated language comprehension. A final section presents three sets of representative results and illustrates the benefits and limitations of eye tracking for investigating the interplay between the perception of the visual world and language comprehension.

The present article reviews an eye-tracking methodology for studies on language comprehension. To obtain reliable data, key steps of the protocol must be followed. Among these are the correct set-up of the eye tracker (e.g., ensuring good quality of the eye and head images) and accurate calibration.

The present work is a description and an assessment of a methodology designed to quantify different aspects of the interaction between language processing ...

Visual Classical Conditioning in Wood Ants

Several species of insects have become model systems for studying learning and memory formation. Although many studies focus on freely moving animals, studies implementing classical conditioning paradigms with harnessed insects have been important for investigating the exact cues that individuals learn and the neural mechanisms underlying learning and memory formation. Here we present a protocol for evoking visual associative learning in wood ants through classical conditioning. In this paradigm, ants are harnessed and presented with a visual cue (a blue cardboard), the conditional stimulus (CS), paired with an appetitive sugar reward, the unconditional stimulus (US). Ants perform a Maxilla-Labium Extension Reflex (MaLER), the unconditional response (UR), which can be used as a readout for learning. Training consists of 10 trials, separated by a 5-minute intertrial interval (ITI). Ants are also tested for memory retention 10 minutes or 1 hour after training. This protocol has the potential to allow researchers to analyze, in a precise and controlled manner, the details of visual memory formation and the neural basis of learning and memory formation in wood ants.

We present a protocol for the classical conditioning of harnessed ants that permits researchers to study visual learning and memory formation at a level of analysis not possible with freely moving individuals.

Several species of insects have become model systems for studying learning and memory formation. Although many studies focus on freely moving animals, ...