The research methods of biopsychology represent a great tool for studying the brain. Thanks to them, we can better understand the functioning of our most mysterious organ. But what exactly are these methods?
Some authors use the term 'psychobiology', such as Donald A. Dewsbury, who defines this field as the 'scientific study of the biology of behavior'. Other scholars, however, prefer the term 'biopsychology', because it is more suitable to indicate 'a biological approach to the study of psychology, rather than a psychological approach to the study of biology'. Thanks to scientific progress, the research methods of biopsychology in recent years have been at the center of enormous revolutions.
How many of the early researchers would have thought that, one day, they would get to observe the functioning of the brain live? Since i research methods of biopsychology there are many, here we will focus only on those who study what happens in the brain under certain conditions.
'Man is the most mysterious and disconcerting object discovered by science.'
Biopsychology and methods of stimulation and observation of the human brain
The ability to observe and record brain activity live it is a goal achieved thanks to the different techniques that have been developed over the course of the twentieth century. These techniques have made it possible to make enormous progress in understanding the functioning of this incredible organ, of which much remains to be discovered.
X-rays with contrast medium
This technique consists in injecting a substance into the body that absorbs i X-ray . In this way, the contrast between the liquid and the surrounding tissue can be observed with a detector.
Cerebral angiography is a diagnostic technique that uses X-rays with contrast medium. It is performed by injecting a radiopaque substance into a cerebral artery, with the aim of observing the circulatory system of the brain while taking an x-ray. This technique is useful for locating vascular lesions and brain tumors .
Computed Axial Tomography (CT)
Through the TAC the structure of the brain can be observed in its entirety. During the medical examination, the patient finds himself in the center of a large cylindrical machine. While lying down, an X-ray tube and a receiver, diametrically opposite, acquire a large number of photographs separately. The acquisition takes place while the emitter and receiver rotate around the subject's head.
The information contained in the photographs is then merged thanks to a computer. This operation allows the reconstruction of a horizontal section of the brain. Usually this can be done through eight or nine horizontal brain sections (cuts). When all the reconstructions have been combined, one is obtained three-dimensional representation of the brain .
Nuclear magnetic resonance (MRI)
With MRI, high resolution images can be acquired thanks to the different waves emitted by hydrogen atoms when activated by radiofrequency waves in a magnetic field. This technology guarantees high spatial resolution and produces images in three dimensions .
Positron Emission Tomography (PET)
PET scans provide physiological information, that is, they produce images of brain activity rather than the structure of the organ. To get these images, it is injected a radiopharmaceutical such as 2-desossiglucosio (2-DG) in the carotid artery of the subject.
Active neurons rapidly absorb 2-DG, and because they are unable to metabolize it, it builds up until it begins to gradually decay. In this way one can observe which neurons are activated, and at what moment, during the different operations of the brain .
Functional magnetic resonance imaging (fMRI)
FMRI offers images of the change in blood oxygenation in the brain regions . For this reason, it is a technique that is very often used in measurement of brain activity . Compared to PET, it also has four advantages:
- The subject is not injected with any substance.
- It provides both functional and structural information.
- It guarantees better spatial resolution.
- It can provide three-dimensional images of the entire brain.
With this method, the variations in magnetic fields that occur on the surface of the scalp are measured. These changes are produced by variations in the models that are at the basis of neuronal activity .
Transcranial magnetic stimulation (TMS)
According to the definition of Vincent Walsh and John Rothwell, transcranial magnetic stimulation is 'a technique for altering the activity of an area of the cerebral cortex, creating a magnetic field through a coil positioned on the patient's head'.
L’EMT It temporarily 'turns off' a part of the brain to assess the effect of this blackout on behavior and cognitive activities .
Harmful methods of biopsychology
The harmful methods are those that destroy some areas of the brain to see what effects they can have on behavior .
- Aspiration injuries. This method is used to cause lesions in certain areas of the cortical tissue that are visible to the naked eye. The tissue is extracted through a thin-tipped glass pipette.
- Radiofrequency injuries . It is about small subcortical lesions . To carry them out, an electrode is used to channel a high-frequency current through the tissue to be destroyed. The size and shape of the lesion depend on three factors:
- Current intensity.
- Configuration of the electrode tip.
- Scalpel cuts. They consist of separating the area of the brain that you want to destroy.
- Cold block. Although this technique is usually counted among the harmful ones, however, it is reversible . Instead of permanently destroying the structures, an area of the brain is cooled and kept above the freezing point. The neurons therefore stop emitting signals e the functioning of that region of the brain stops. In this way, it is possible to observe which alterations in behavior can cause intervention on certain areas. When the temperature returns to normal, normal brain function is restored.
Another research method in biopsychology exploits electrical stimulation. A structure of the nervous system it is electrically stimulated to obtain data on its operation. A bipolar electrode is usually used.
This stimulation affects neurons and alters their behavior. The effect that is obtained usually it is contrary to that caused by injuries. If, for example, a drastic reduction in sleep results from an injury, stimulation can lead to a disproportionate response to sleep.
Harmful methods with electrophysiological recording
- Intracellular registration of a unit. This technique is performed by introducing a microelectrode inside a neuron. Provides a record of the gradual fluctuations of the membrane potential of the same.
- Extracellular registration of a unit. A microelectrode is placed in the extracellular fluid surrounding the neuron and its impulses are recorded through it. However, information on the membrane potential cannot be collected with this method.
- Registration of multiple units. In this case the electrode tip is larger than that of a microelectrode, so it is able to collect the signals of several neurons at the same time. The action potentials that are thus detected are led to a circuit that integrates and adds them.
- Invasive EEG (electroencephalogram) recording. In this case the electrodes are implanted. When looking for recordings of cortical EEG signals, stainless steel “nut” cranial electrodes are used. For subcortical signals, cable electrodes implanted by stereotaxic radiosurgery are usually used.
'Anthropology, biology, physiology, psychology have put together veritable mountains of material to erect before man, in all their range, the tasks of his own bodily and spiritual perfection and of his development further.'
Research Methods in Biopsychology: A Long Way to Go
The most representative research methods in biopsychology were discussed in the article. However, it is worth mentioning that there are other techniques that allow you to study other parts of the body . Among these we can find the measurement of muscle tension, the recording of eye movements, skin conductivity or cardiovascular activity.
The research methods of biopsychology in recent years have undergone a considerable evolution, but this does not mean that the techniques currently used should be considered definitive. That is to say that in a few years new technologies could emerge that at this moment we cannot even imagine.
All of this will contribute to the advancement of neuroscience which, in turn, they will help improve the quality of life of the many people suffering from some kind of neurological disease .
- Dewsbury, D. A. (1990). Psychobiology. American Psychologist .
- Pinel, J., & Barnes, S. J. (2017). Biopsychology. Pearson College Div .
- Walsh, V., & Cowey, A. (2000). Transcranial magnetic stimulation and cognitive neuroscience. Nature Reviews Neuroscience . http://doi.org/10.1038/35036239