Monday, January 14, 2008

Physiological psychologists have developed various methods for looking at the structures and functions of the human brain

By Sudipa Sarkar
Introduction

Physiological psychology, sometimes related to psychiatry, is a special part of psychology which is concerned about the physiological causes behind the psychological processes and functioning. According to Wilhelm Wundt (1902), physiological psychology entails the principal object whereupon all other varieties of psychological elucidations are directed. He affirmed that the experimental alteration and adaptation at the physiological level either directly or indirectly frequently produces a simultaneous change in the process of consciousness. There are various methods employed to study the neural basis of behaviour. This paper aims to identify the various methods for analysing the structure and functions of the human brain along with reference to the relative intrinsic worth and imperfection of different techniques.

Relation between Physiological Psychology and Behaviourism

It is assumed that the branch of physiological psychology stemmed from the introduction of the Wundt’s classic book about the principles of physiological psychology (Grundz├╝ge der physiologischen Psychologie: Wilhelm Wundt, 1874) came into existence. According to Ladd and Woodworth (1915), the study of Physiological Psychology actually explores the correlations among the structure of human nervous system and brain structure with the conscious phenomenon. Wundt explained the correlation among psychology and physiology by emphasizing the positive correlation and interaction among psychological introspection to that of methods employed in the experimental physiology ensuring the significant correlation among physiological psychology and behaviourism. Examples include,

1) Mood can be dependent on sensory input as well as I-function (also it may become prevalent independent of sensory input) ensuring that the changes in an individual’s pharmacological makeup can induce a variation in mood, sleep disturbance as well as depression (Alicia Ebbitt, 1998).
2) Studies suggested that there is a significant role of Amygdala in producing fear and anxiety in an individual. Amongst the 22 regions found in Amygdala, two regions have been identified as being interrelated to the onset of fear (Doug Holt, 1998) and the medial and caudal aspects of Amygdala are considered to be interrelated to the defensive or aggressive behaviour pattern (Isaacson, Robert). The periaqueductal gray suppressed within Amygdala is considered to be involved in the interpretation of fear as well as protection and defensive reactions (Carrive, Pascal, 1993)
3) The ventromedial and lateral hypothalamus, together known as satiety centre, has been identified to administer the eating behaviour of an individual. Decrease is epinephrine in ventromedial hypothalamus is considered to be correlated to the prevalence of anorexic behaviour in an individual by adopting a low rate of eating, increasing rate of activity, reducing carbohydrate intake, and rebounding often with overeating phenomenon (Jeremy Hirst, 1998)

Various Methods Employed in Physiological Psychology

Physiological Psychology entails different methods to incorporate and understand the structure and functions of the human brain in order to find out the psycho-physiological causes of human behaviour and motivation. In the modern world, there are number of methods employed to strengthen the association between biology and behaviour emphasizing primarily on two crucial factors including the technology of brain imaging such as MRI, CT and PET scans in order to identify the physiological correlation with behaviours on the basis of searching through the structures and brain activity, development of genetics by focusing the causes of various mental disorders on the basis of genes. The primary methods employed in understanding the concepts of physiological psychology comprises the followings –
1) Stereotaxic Surgery
Stereotaxic Surgery is a method where the surgery is performed by defining the three major areas of the brain using the atlas. The significant objective of this surgery is to either place electrodes for recording or else stimulating purpose or to destroy a particular region of the brain.
2) Lesion Production
This method is characterized by the destruction of the particular area of the brain by employing the electrodes along with chemicals such as kainic acid or 6-hydroxydopamine and passing through electrical current (either AC or DC). The other methods involved conducting lesion production may include either surgical elimination of a tract or suction removal of the area of the brain.
3) Electrical Brain Stimulation
This feature is resembled with what its name implies. The method is employed by electrical stimulation of the brain cell.
4) Microinjection
Microinjection is conducted by injecting small quantities of drugs or neurotransmitters into the particular regions of the brain cell.
5) MRI techniques
MRI or Magnetic Resonance Imaging is a technique used to visualize and receive a comprehend information of the inside of the living organism by means of demonstrating the pathological and physiological changes in living tissues.
6) PET Scan
PET or Positron Emission Tomography is a method used in clinical setting that enables to understand and analyse the acquired physiological images on the basis of the detection of radiation as a result of the emission of protons.
7) CT scan
Computed Tomography or CT scan (also known as Computed Axial Tomography or CAT) is an imaging method prevalently used in medical clinical practices by employing the method of tomography inclusive of digital geometry processing producing three dimensional images. The CT scan of brain is primarily known as cerebrovascular accidents and intracranial hemorrhage.

Physiological Psychology entails different methods to incorporate and understand the structure, stereosurgic intervention amongst important to them. In 1906, Robert Henry Clarke and Victor Horsley first developed stereotaxic or stereotactic surgery in order to target and intervene the specific areas of the brain by positioning the head with the help of Horsley-Clarke frame. The neurosurgical intervention following the method of stereotaxic surgery method gave a rise in 1946 with the support of Spiegel and Wycis. One of the crucial aspects of the stereotaxic surgery is to combine the method of delivering viruses as therapeutic agents. Lieberman et al (1995) infused different subtypes of adeno associated virus, while in 2001; Sanchez Pernaute et al successfully performed the intervention by using lentiviral vectors. The potential efficiency of the outcome of the surgery is appraised by immunohistochemical detection of the expression of thetransgene product, an aromatic aminoacid decarboxylase (AADC) or a reporter gene. In the case of the interventions described above the green fluorescent protein (GFP) has been used after 3 weeks of the infusion in the striatum. During the stereotaxic surgery the primary concern is to employ the method of cell transplantation to keep the cells alive throughout the process.

A study conducted by Hokama et al (March, 1993) on the indications and limitations for computerized topography guided stereotaxic surgery, argued about a poor outcome of the surgical procedure by emphasizing on postoperative complications prevalent in older clients as well as clients having serious neurological deficits or chronic disorders. J. L. Fox and R. C. Green (1968) suggested a probable limitation obligatory to the intensification and parallax attributable to an x-radiation point source coming from the x-ray film and angular intensification attributable to x-ray projection of an angle in an inclined plane in the case of ntracranial stereotaxic probe-target aligned to a stern polar coordinate system and polar range result.

Paul Christian Lauterbur (born in May 6, 1929), an American chemist, is considered to be the inventor of the MRI technique. MRI is used in clinical setting in order to identify and distinguish between pathologic tissues with that of normal tissues (Lauterbur, P.C, 1973). The main advantage of this technique is its safe use in various incidences with the use of strong magnetic field along with non-ionizing radiation in the range of radio frequency compared to the CT scan as well as conventional X-rays comprised with ionizing radiation resulting in the increasing rate of malignancy particularly in foetus. The other advantage of MRI technique includes comparable resolution with better contrast resolution compared to the CT scan technique characterizing good spatial resolution (Ljunggren S. J, 1983).

However, there are significant researches conducted on the effects of MRI technique on human cells and tissues by affirming non-harmful effects on foetus in particular, but the recommended guideline as a precautionary measure is to avoid MRI technique as much as possible during pregnancy (Ljunggren S. J, 1983). The unusual shape of the MRI tube makes some individuals to have claustrophobia showing an intensified intolerant attitude towards the technique.

The primary and most important aspect of CT scan technique involves the complete elimination of superimposition of non-related or irrelevant parts of the area of interest (Tweig D, 1983). The subtleness of the identification of tissues on the basis of density is quite prevalent compared to that of radiography. Moreover, the CT scan technique is inferred into various formats including axial, coronial planes depending on the pattern of the diagnosis. The most common disadvantage associated with the CT scan technique is the high radio-active content of the CT scan technique.
Randal C. Archibold (2001) argued that there are various benefits associated with the PET scan technique affirming the effectiveness of detection of changes in biochemical processes in the intracellular level, short-lived radio-activity resulting in potentially less dangerous effect. On the other hand, there are few disadvantages associated with the PET scan technique such as deriving misleading information about chemical imbalances as a result of PET scan especially in the case of diabetic patients or patients having food prior to the experimentation (H.F. Judson, 2003), the higher price associated with the PET scan technique have made it to be compared with other similar techniques.
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1 comment:

Unknown said...

hey thanks this article gave very brief discreption which is very helpfull

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