hi and welcome back to perceptual motor motivation and emotion course in the second video we will look at some of the most commonly used research methods in neuroscience Neuroscience which is often used interchangeably with the terms biological psychology and psychobiology is not just a science that studies the anatomical structure of the nervous system but also the behavioral correlates of nervous system structures in other words Neuroscience seeks to understand the relationship between brain structure and brain function there are many research methods used in the field of Neuroscience these methods can generally be divided into several categories Each of which has its own emphasis the first category is research that focuses on the behavioral effects of damage or dysfunction of the nervous system this type of research looks at which behaviors are impaired or decreased after damage to a certain brain area the second category is research that focuses on the effects of stimulation to certain areas of the brain this type of research looks at how behavior is increased due to stimulation applied to a specific area of the brain the third category is research that focuses on recording brain activity while subjects perform a certain Behavior this method seeks to understand the difference between brain activity that occurs when a task is being performed as opposed to when no task is being performed or a comparison task is being performed then the fourth category is research that focuses on the correlation between brain anatomy and certain behaviors these types of research look at the extent to which people with abnormal behaviors also have abnormalities in brain structure in 1861 the French neurologist Paul broca discovered that a patient who had lost the ability to speak had damage to part of his left frontal cortex coincidentally he also found that other patients with similar language production impairments also had damage around the same area in particular damage occurred to the area that we now refer to as Broca's area although there were plenty of further explorations of Broca's area that were necessary to determine the exact functions of this brain area Paul Broca's Discovery revolutionized the science of Neurology especially considering that at the time many Physicians doubted the claim that different areas of the brain had different functions to examine the effects of brain damage on Behavior researchers often used surgical techniques to remove certain parts of the brain of laboratory animals this technique is referred to as an ablation procedure in addition to the ablation technique researchers can also use a lesion technique to damage localized brain areas specifically by delivering electrical currents through electrodes implanted into the brain lesions are performed through a stereotaxic instrument which is a tool that helps researchers accurately place electrodes in specific areas of the brain you can see an illustration of this instrument on the current slide placement of the electrodes is determined with the help of a stereotaxic atlas or map once the brain area has been identified the researchers will place the electrodes in the targeted area to do this researchers would first anesthetize the animal drill a small hole in its skull with a stereotaxic instrument insert the electrodes and lower the electrodes into the target area before delivering an electrical current that is just strong enough to damage the target area this technique has been carried out quite often by researchers for example researchers have used the lesion technique to investigate the role of the hypothalamus in feeding and drinking behaviors usually following the death of the animal whose brain has been lesioned the researchers would slice the brain and apply a staining technique to verify the actual location of the damage to ascertain that the observed impairments in Behavior are indeed due to the lesion the researcher would often also apply an identical procedure to a control group of animals but without electrically damaging the brains of these control animals this method is known as sham lesion though widely used in the past the application of electrical current to damage a brain area as discussed in the previous slide often inadvertently damages passing axons that are not part of the targeted area nowadays researchers produce brain damage by injecting chemicals that damage targeted neurons or temporarily disable the neurons without damaging passing axons they can also inject chemicals to paralyze certain types of synapses while leaving other synapses unaffected another option is the use of a gene knockout approach which is a technique through which a genetic mutation is artificially induced with a mutation selectively inactivating certain genes that regulate the activities of certain neurons certain neurotransmitters or certain receptors transcranial magnetic stimulation or TMS is another technique this technique involves applying a magnetic field to an area of the scalp which consequently stimulates neurons located underneath that magnetic field as long as the stimulation is applied briefly and mildly with stronger magnetic fields however neurons located under the magnetic field will be inactivated resulting in a virtual lesion that lasts longer than the magnetic stimulation itself but does not produce permanent damage to the brain one advantage of TMS is that it allows researchers to study behavior by controlling the function of several areas of the brain by intentionally activating those brain areas and then deactivating those same brain areas next we'll look at research that looks at the effects of brain stimulation on Behavior the logic behind this method is quite simple if brain damage interferes with some normal behavior then brain stimulation should be able to induce or elicit the behavior in question in the past brain stimulation studies were usually done by inserting electrodes into an area of an animal's brain and subsequently sending brief mild electrical currents to stimulate neurons in the area this method has its drawbacks however in that the applied stimulation will stimulate all types of neurons as well as passing axons despite the fact that a given area of the brain has many different types of neurons with different functions to address such limitations a popular brain stimulation approach and used today is the optogenetics technique which involves the use of light to control a selected population of neurons this technique was developed by a team led by Carl diceroth and began to be widely used in 2009 using this method a researcher can control the excitatory or inhibitory responses of a group of neurons in a small area of the brain with millisecond accuracy successful implementation of optogenetics requires three steps that are interrelated and rather Inseparable from one another the first step is to find or create a protein that responds to light by producing an electrical current certain microbes produce proteins like this and these proteins are modified by optogenetics researchers for example one protein can react to light by opening sodium channels and thus producing an excitatory effect on neurons other proteins react to light by opening chloride channels and producing an inhibitory effect the second step is to develop a virus that could insert one of these proteins into a certain type of neuron or even to a specific part of a neuron such as an axon or a dendrite the third step is to develop very thin Optical fibers that can deliver a highly specific amount of light two neurons in the targeted area of the brain this technique has also been applied to patients to control the Sleep Disorder known as narcolepsy as well as to control other psychiatric conditions if damage to an area of the brain interferes with the behavior and stimulation of the same area of the brain increases Behavior we can reinforce our conclusion about the function of that specific brain area by investigating whether there is indeed an increase in the activity of said brain area while a person is performing the behavior to perform such a feat we would need techniques that enable us to record brain activity such a technique can also help answer questions about which brain areas increase their activity when a person is performing certain Behavior or a specific cognitive activity one of the methods for recording brain activity is intracranial recording which is used on animal subjects through implantation of electrodes into the brain this technique allows for the recording of the activity of a single neuron intracranial recording is a technique that is constantly evolving and allows researchers to record from tens to hundreds of neurons simultaneously another way of recording the activity of the nervous system is through electroencephalography or EEG this technique records the electrical activity of the brain through electrodes that can range widely in number from just a few electrodes to more than 100 electrodes that are attached to the scalp these electrodes measure the average electrical activity per millisecond of the cell population beneath the electrodes the output is then sent to an amplifier and recorded by a special software EEG recordings are useful for distinguishing between brain activity when we're awake and when we're asleep as well as for comparing brain activities in different stages of sleep EEG can also help doctors diagnose brain abnormalities associated with conditions like epilepsy the next technique is magnetoencephalography or Meg in contrast to EEG Meg measures the magnetic fields generated by brain activity like EEG Meg also has excellent temporal resolution as it is able to record changes in brain activity from one millisecond to the next yet another technique is positron emission tomography or pet or pet which is a brain scanning technique that produces high resolution images of brain activity by recording radioactive emissions from injected chemicals in a research study that employs pets participants would first be given an injection of glucose containing radioactive atoms brain areas that are most active would increase their use of glucose which means that tracking glucose levels through radioactive atoms can provide some clue about how active a particular brain area is relative to others in particular through the use of special detectors a pet fishing can identify regions of the brain that uses the highest level of glucose by measuring the radioactivity of different areas of the brain the areas with the highest levels of radioactivity are those with the most active neurons it's important to note however that pet scan utilizes very expensive radioactive chemicals made by a very expensive device called a cyclotron cyclertrons themselves are highly costly and as a result Pet Imaging is usually only available in research hospitals in addition pet exposes the brain to Radioactive rays that can be potentially harmful to one's health the next brain recording instrument is fmri which is short for functional magnetic resonance imaging the fmri machine scans the activity of hemoglobin in the blood which is a blood protein that binds oxygen hemoglobin with oxygen will react more strongly to a magnetic field than hemoglobin without oxygen and as some areas of the brain become more active two events will occur first blood vessels will dilate to allow more blood to flow to the area second because the active area of the brain needs oxygen the percentage of hemoglobin with oxygen in the brain also decreases an fmri scanner is designed to respond to both of these events in Behavioral Studies with fmri researchers would typically record participants brain activity while participants perform a certain task and then compare this observed brain activity with the brain activity that's seen when participants perform some other unrelated tasks let's now look at research that focuses on correlating brain anatomy with behavior using this method researchers would observe people who behave abnormally and observe the anatomy of their brain to look at the brain anatomy of humans a special technology is needed one such technology is computerized axial tomography or better known as a CT scan or CAT scan to conduct research with a CT scanner a researcher would inject the special dye into the participant's bloodstream to increase the contrast in the CT scan image and then the researchers would place the participants head into a CT scanner in the CT scanner x-rays are passed through the participant's head and recorded by special detectors the CT scanner is rotated slowly until measurements have been taken at each angle of rotation from these measurements a computer will assemble or construct an image of the brain CT scans are most useful for detecting tumors and other structural abnormalities in the brain the last method of correlating brain anatomy with behavior is magnetic resonance imaging or MRI which is a brain scanning technique that uses measurements of electromagnetic energy released by The nuclei of hydrogen atoms when a strong magnetic field about 25 000 times the Earth's magnetic field is applied by measuring this energy the MRI device forms a picture or an image of the brain MRI images are highly detailed with anatomical details smaller than a millimeter in diameter one of the disadvantages of MRI is that participants have to lie down without the slightest movement in a very cramped and noisy machine this procedure is therefore usually not suitable for children or people with claustrophobia researchers who use MRI sometimes find that certain areas of the brain are larger in people with certain characteristics or traits but we still need to view the results of these correlational studies with some degree of skepticism many MRI studies use small samples and the results of many MRI studies that correlate brain anatomy with behavior often cannot be replicated this slide marks the end of the video on research methods in Neuroscience thank you for your attention