Psychology / Neurobiological Basis Of Behavior

Psychology / Neurobiological Basis Of Behavior

    The notion that the brain is the organ of behavior is an old one. In the 19th century Frans J Gall proposed the phrenology theory. According to this theory, brain is the organ of Mental and Moral faculties and divided the cerebral cortex into areas representing these faculties.

Although the phrenology theory is not accurate but it directs our attention to the facts that brain plays a pivotal role in the production of our behaviors.

Current status of neurobiology and behavior:

In recent decades science has developed increasingly sophisticated techniques for investigating the nervous system. Among the most important tools are the neurophysiological like evoked potentials (EP) & electro-encephalography (EEG): structural imaging by computerized axial tomography (CAT) scanning and magnetic resonance imaging (MRI): functional imaging as single photo emission tomography (SPECT) and Positron emission tomography (PET) scanning .

Scientists often combine these techniques to study brain activity in unprecedented detail.

The recent studies of the functional neuroscience demonstrated that certain brain areas are responsible for particular psychological function. For example, the limbic system contributes to emotional experience and expression, frontal lobe for cognition and for motivation, reticular activating system for sleep and in combination with the cerebral cortex it serves for process or attention.

Brain organization and behavior:

• The human brain is composed of two hemispheres; left and right. Most functions of the cerebral cortex are represented on both hemispheres. In other words, halves of the occipital lobe are responsible for vision, both halves of the temporal lobes are responsible for hearing, and both halves of the frontal cortex are responsible for planning and decision making.
• There is one function that is typically unilateral and found on one hemisphere-language which is most often located on the left hemisphere. Human language is separated in the brain into areas for comprehension and speech. Wernicke's area is responsible for making sense of words that we hear or read, while Broca's area is responsible for organizing the necessary muscular activities required for speech, such as controlling our lips, tongue, and breathing so that we can make sounds.
• In general, anterior (more forward) areas of the cortex are involved with planning and movement, while posterior (near the back) cortical areas are involved with the processing of sensory information.

Brain Areas and Functions :

Frontal lobe :- Decision-making, reasoning, planning, behavioral inhibition, and personality.

Parietal lobe:- Sensation and perception of certain senses including touch.

Occipital lobe :- Sensation and perception of visual information.

Temporal lobe :- Sensation and perception of auditory information, language comprehensions.

Limbic system :- Emotions, learning and memory, motivation.

Hypothalamus:- Maintains homeostasis (body temperature, eating, drinking, sleep, metabolism).

Mid brain :- Neurotransmitter production.

Brain stem :- Vital body functions (breathing, regulation of heart rate, consciousness).

Cerebellum :- Motor coordination and balance, motor learning.

Now we shall discuss the frontal lobe and limbic system in some details:

Frontal lobe function related to behavior:

1-Ability for initiatives and planning.
2-The elaboration of personality traits which are different from one person to another. For example, we all have different likes and dislikes, such as hobbies, different senses of humor and different preferences, such as tastes in art or music.

3-Control of behavior and behavioral inhibition. In other words, certain areas in the frontal cortex are responsible for decision making and acting appropriately based on those decisions. We all know the difference between what is right and wrong. Certain areas of the cerebral cortex, including the frontal cortex, normally suppress certain thoughts, actions, and feelings.

Function of the limbic system:

1. The limbic system is associated with emotion and motivation.
2. The amygdala is known to attach emotional significance to sensory input.
3. Olfactory stimuli enter the limbic loops via the endorhinal cortex of the parahippocampal gyrus.
4. The limbic system has a direct influence on neuroendocrine, autonomic and behavior mechanisms, and it also has a role in functions such as flight, homeostasis, self-maintenance, appetite and sexuality.
5. The limbic system areas are highly interconnected with the rest of the brain,and they likely form a gateway for communication between the cerebral cortex and the hypothalamus.
6. This gateway allows for cognitive processes to modify the effect of the limbic system on hypothalamic functions.