module 3 lecture

Introduction to Biopsychology

Biopsychology refers to the biological foundation of psychology, encompassing the brain, central nervous system (CNS), and physiological aspects of human behavior. It is crucial for understanding human psychology and should provide a solid foundation for anyone in psychology as a major or profession. Knowledge of biopsychology influences the interpretation of behaviors and thought processes by linking genetic and neurological factors to personality and actions.

Nervous System Structure

The nervous system is divided into two main parts:

• Central Nervous System (CNS): Comprised of the brain and spinal cord, it is the primary focus in psychology.

• Peripheral Nervous System (PNS): Comprises the rest of the nervous system, providing connections to the limbs and organs.

Components of the CNS

• Somatic Nervous System: Controls voluntary movements and sensory input.

• Autonomic Nervous System (ANS): Regulates involuntary body processes, impacting psychology notably.

Neurons: The Building Blocks of the Nervous System

Neurons are specialized cells responsible for transmitting information throughout the body. They process and communicate information via distinct structures:

• Cell Body (Soma): Contains the nucleus, where information processing occurs. It integrates signals received from the dendrites and determines whether to send an action potential.

• Dendrites: Extensions that receive signals from other neurons. They have numerous branches that increase their surface area, allowing them to receive a large amount of information from other neurons.

• Axon: Transmits impulses away from the cell body toward other neurons. The axon is often covered by a myelin sheath, which facilitates faster signal transmission. Each axon ends in multiple terminal buttons that form synapses with other neurons.

• Terminal Buttons (Axon Terminals): Release neurotransmitters that communicate with adjacent neurons. The transmission of signals across synapses is critical for the functioning of neural networks.

Transmission of Information

Action potential travels along the axon to the terminal buttons. The analogy of throwing a ball illustrates this transmission:

• Cell Body = Shoulder (initiates action)

• Axon = Arm (carries information)

• Dendrites = Outstretched hands (receive information)

Synapse and Neurotransmitters

• Synapse: The gap between neurons where neurotransmitters transmit signals. The synaptic cleft is a minute space where neurotransmitter release and receptor binding occurs.

• Neurotransmitter: Chemical messengers that carry messages across the synapse. Different neurotransmitters serve various functions, affecting mood, motivation, and cognitive processes. Examples include:

  • Serotonin: Related to mood regulation, with imbalances linked to anxiety and depression.

  • Dopamine: Related to movement and reward; alterations in dopamine levels are associated with psychiatric disorders, including schizophrenia and addiction.

• Reuptake: The process through which neurotransmitters are reabsorbed by the terminal button after signal transmission, regulating the availability of neurotransmitters for future action potentials.

Importance of Neurotransmitters

• Dopamine: Influences movement, motivation, and feelings of reward. Abnormal levels can lead to neuropsychiatric conditions such as Parkinson's Disease.

• Serotonin: Affects mood, euphoria, and satisfaction; low levels can result in mood disorders such as depression.

• Endorphins: Natural pain relievers that help elevate mood and create a sense of well-being.

• Oxytocin: Promotes social bonding, emotional connections, and stress regulation through its effects on social behaviors.

Myelination and its Role

• Myelination: The process of adding a protective fatty sheath around axons, enhancing signal speed and efficiency in neuronal communication. It is crucial for the rapid transmission of actions and reflexes.

• The importance of myelin in habitual behaviors: Efficient and automatic actions are often myelinated (e.g., brushing teeth). Lack of myelin can lead to issues in movement and cognitive functions.

Rebuilding Myelin

Activities that promote myelination can enhance neurological pathways and habits. Use it or lose it principle: Regularly used neuronal pathways strengthen through myelin development, whereas unused pathways may diminish.

Impact of Drugs on Neural Function

Drugs can interact with neurotransmitter systems as either:

• Agonists: Mimic neurotransmitters and enhance their effects, thus increasing neural communication.

• Antagonists: Block the effects of neurotransmitters, reducing the efficacy of communication.

Tolerance and habituation develop as receptors adapt to the continual presence of a drug, leading to down-regulation (fewer available receptors).

Examples of Drug Interaction

• Cannabis and THC: THC impacts dopamine release and can lead to down-regulation if used excessively. Varying concentrations of THC in cannabis can enhance the potency of dopamine stimulation, impacting behavior and psychological health.

Recovery from Neurotransmitter Imbalance

Addressing neurotransmitter imbalances involves time and may require changes in lifestyle and habits. It is encouraged to focus on healthier dopamine and serotonin sources by:

• Engaging in rewarding, healthy behaviors.

• Fostering positive social connections.

• Reducing reliance on high-dopamine-producing activities, such as excessive screen time or sugary foods.

Conclusion

Evaluating habits and neurotransmitter health is vital for personal psychological growth and improving interactions with others. Self-reflection on myelination, neurotransmitter levels, and behavioral habits aids in developing healthier lifestyles.

Biological Defense Mechanism in the Brain: Regulation of Excess Neurotransmitters

When excess neurotransmitters are present in the brain, a biological defense mechanism known as reuptake is employed. This process involves the reabsorption of neurotransmitters by the presynaptic neuron from the synaptic cleft after signal transmission. By regulating the availability of neurotransmitters for future action potentials, reuptake helps maintain neurotransmitter balance, preventing overstimulation of receptors and ensuring proper neural communication.

Downregulation refers to the process by which a cell decreases the number of receptors or the sensitivity of receptors in response to a stimulus, often due to prolonged exposure to a particular neurotransmitter or hormone. This mechanism occurs in the context of neural and hormonal signaling, primarily as a way to maintain balance in biological systems.

When excessive stimulation occurs, such as from drug use or increased levels of neurotransmitters, cells adapt by internalizing or reducing receptor density on the cell surface. This can lead to decreased responsiveness to that neurotransmitter or hormone, potentially necessitating higher levels of the substance for the same effect. Downregulation is significant in various conditions, including addiction, where the body adapts to the presence of drugs like THC in cannabis, leading to diminished effects over time.