Biological Approach

→ What is the Biological Approach?

• Behaviour is strongly influenced by the brain, both the structure and functions of the brain.

• It supports the importance of the brain and it focuses on how our nature (hereditary aspects) are significant to the structure and functioning of the brain.

• It was developed as a direct influence of the work of Charles Darwin - Theory of Evolution. This eventually led to the development of Evolutionary Psychology.

→ Evolutionary psychology:

• According to it, evolution has shaped the brain, body and behaviour. Due to evolutionary pressure, there was no other option but to adapt. So humans inherited characteristics (nature) that were pivotal to their survival in the environment they were in.

• The human brain is much larger and more efficient in its functioning than it was. This adaptation was necessary to develop the ability to think and reason.

→ Nature vs Nurture:

• Heredity - genetics determine who we are.

• Environment - experience determines who we are.

• The biological approach considers heredity (nature) as being very important.

• Although there is an amount of instinctive behaviour in humans, the majority of behaviour is learnt through experiences. However, we cannot ignore innate/genetic (heredity) factors.

• By means of family and twin studies (monozygotic and dizygotic twins), researchers focused on the way genetic factors affect behaviour. Twin studies focused on monozygotic (identical) twins and dizygotic (fraternal) twins and assessed the similarities in both appearance and behaviour, amongst others. In some cases, twins were adopted by separate families and so it was possible to research which traits were a result of heredity and which influenced by the environment.

• Active covariation - children of differing genetic abilities look for situations that reinforce their genetic differences.

• Passive covariation - parents of high genetic ability provide a more stimulating environment than parents of low genetic ability.

• Reactive covariation - individuals of high genetic abilities receive a different treatment. Their abilities influence how others treat them. They are more often than not treated better or given more opportunities.

→ The nervous system:

• Contains all the nerve cells in the body. It’s divided into 2 sub-systems: The Central Nervous System (CNS) and The Peripheral Nervous System (PNS).

• Central Nervous System - consists of the brain and the spinal cord. It’s protected by bone and fluid circulating around it. Makes decisions for the body.

• Spinal Cord - nerves running from the brain to the lower part of the back. The spinal cord and the brain are interconnected and so they work together. Function 1: Sensory information into the PNS which is then relayed to the brain (CNS), this is done through the use of receptor nerves. Function 2: Motor information from the brain (CNS) to the PNS, this is done through the effector nerves. Receptor nerves transmit information to the brain via the spinal cord. Instructions from the brain are sent via the effector nerves. However, with reflexes the information goes directly from receptor nerves to effector nerves.

• Peripheral Nervous System - consists of all the nerve cells of the body not contained within CNS. It’s used to transmit information between CNS and receptors and effectors outside the CNS. Linked with external sensory organs and receptors in internal structures. Composed of the somatic nervous system and the autonomic nervous system.

• Somatic nervous system - concerned with interactions with the external world and so voluntary movements of the skeletal muscles. It consists of nerves carrying signals from eyes, ears, skeletal muscles and the skin to CNS. It also carries signals from CNS to skeletal muscles, skin, etc.

• Autonomic nervous system - concerned with the body's internal environment and so involuntary movement of the non-skeletal muscles (ex: heart, lungs, eyes, stomach and blood vessels of internal organs). Divided in: Sympathetic nervous system and Parasympathetic nervous system.

• Sympathetic nervous system - this function starts working when there is need for awakening, excitement, and energy. These changes prepare the body for fight or flight and so it’s the arousing system. When the SNS is affected, heart rate increases, reduced activity in the stomach, pupil dilation or expansion and relaxation of the bronchi in the lungs.

• Parasympathetic nervous system - this function starts working to calm down and to save energy. It’s involved when we rest and digest. When the PNS is affected, heart rate decreases, increased activity in the stomach, pupil contraction and constriction of bronchi of the lungs.

→ The brain:

• Forebrain - located towards the top and front of the brain. Main parts: a) Cerebrum - 70% of all neurons in CNS. Crucial role in thinking, use of language and other cognitive skills. b) Limbic system - Amygdala (anger and aggression) and Hippocampus (learning and memory). It regulates the emotions and is significant for learning and memory. c) Thalamus - involved in wakefulness and sleep. d) Hypothalamus - control of body temperature, hunger, thirst, sexual behaviour, endocrine system (produce and release hormones) and reactions to stress. e) Basal Ganglia - voluntary motor control, motor (procedural) learning, eye movements, cognitive function and emotions.

• Midbrain - involved in vision, hearing and control of movement. It contains the reticular activating system which regulates sleep, arousal and wakefulness influencing heart rate and breathing rate. Main components: a) Tectum - consists of visual receptors and auditory receptors. b) Cerebellum - also part of the hindbrain. It’s involved in body balance and coordination. ‘Overlearned’ skills are found here (ex: driving a car, riding a bicycle).

• Hindbrain - known as the reptilian brain. Main parts: a) Medulla oblongata - control of breathing, digestion and swallowing. It’s also part of the reticular activating system. b) Pons - control of consciousness (shared with midbrain and it’s also part of the reticular activating system). Also involved with vision and it’s a relay station between different parts of the brain. c) Cerebellum - refer to midbrain.

• Cerebral cortex - outer layer of the cerebrum. It’s important in terms of our ability to perceive, think, remember and use language. It consists of four lobes, all with different functions. The entire brain is divided in two hemispheres. Lobes: a) Frontal lobe - reasoning and abstract thinking, motor processing (planning and control of movement - primary motor cortex). Important for fine motor skills. b) Parietal lobe - somatosensory processing- sensations in the skin and muscles of the body. Receives information regarding senses (temperature, pain, pressure). c) Temporal lobe - auditory processing. Involved with speech perception. Respond to sounds - high or low pitch. Meaning of words and concepts stored here. If damaged, a person will have semantic dementia - loss of information about word meaning. d) Occipital lobe - visual processing. 50% of cerebral cortex is devoted to visual processing.

• Hemispheric specialisation - the brain has 2 hemispheres. Each hemisphere differs its function - hemispheric specialisation. One hemisphere may be more dominant over the other for certain processes, for example: in the majority of people, language abilities are based mainly on the left hemisphere. Most of what is known about hemispheric specialisation comes from split-brain patients. Most of these patients suffered from epilepsy (seizures) and their Corpus Callosum (bridge) was cut, and without the Corpus Callosum, information isn’t transferred from one hemisphere to another.

• Left hemisphere - right hand control, writing, language, scientific skills, mathematics, lists, logic and linear thinking mode.

• Right hemisphere - left hand control, emotional expression, spatial awareness, music, creativity, imagination, dimension, gestalt (whole picture) and holistic thinking mode.

• Lateralization - ‘going to one side’.

• Split-Brain studies - to end severe whole-brain seizures, some people have had surgery to cut the **corpus callosu**m, a band of axons connecting the hemispheres.

• If the brain is damaged, especially in the general association areas of the cortex: it doesn’t repair damaged neurons, but it can restore some function; it can form new connections, reassign existing networks, and insert new neurons, some grown from stem cells.

• Brain organisation - it’s interconnected, it’s hierarchical (processing takes place at various levels) and functional differentiation (certain areas are responsible for specific functions).

→ Ways of studying the brain:

• Event-related potentials (ERP) - stimulus is presented and scalp-electrodes record brain activity. Used for timing of cognitive processing.

• Positron emission tomography (PET) - works during the detection of positrons (particles emitted by some radioactive substances). Used to study episodic memory.

• Magnetic resonance imaging (MRI and fMRI) - radio waves used to excite atoms in the brain, thus producing magnetic changes. These changes are recorded on the computer giving a 3d picture. It tells us about the structure of the brain rather than the functions. fMRI are used to understand functions of the brain and to understand which brain regions are activated.