Chapter 2 The Biology of Mind

Definition: Neurons are the basic building blocks of the nervous system, known for their ability to transmit information through electrical and chemical signals.
Types of Neurons:
- Sensory Neurons: Carry messages from the body to the brain.
- Motor Neurons: Carry messages from the brain to the body’s muscles and glands.
- Interneurons: Communicate within the brain and spinal cord, processing information between sensory input and motor output.

Neural Impulses: Information is transmitted as electrical impulses known as action potentials, which are all-or-nothing responses.
Transmission Process:
1. An action potential reaches the axon terminals, stimulating the release of neurotransmitters.
2. Neurotransmitters cross the synaptic gap and interact with receptor sites on the receiving neuron.
3. If the signal is strong enough, the receiving neuron may generate its own action potential.
4. Through reuptake, excess neurotransmitters are absorbed back into the sending neuron.

Neurotransmitters: Chemical messengers that travel across synapses influencing behavior and emotions.
- Acetylcholine (ACh): Key for muscle action, learning, and memory.
- Endorphins: Natural painkillers linked to pleasure and pain control.
Drug Interaction:
- Agonists: Mimic neurotransmitters, enhancing effects.
- Antagonists: Block neurotransmitter effects, impeding communication.

Purpose: The nervous system is crucial for receiving information from the environment, processing it, and sending responses back out.
Main Divisions:
1. Central Nervous System (CNS): Comprises the brain and spinal cord.
2. Peripheral Nervous System (PNS): Connects CNS to the body, including:
  - Somatic Nervous System: Controls voluntary muscle movements.
  - Autonomic Nervous System: Controls involuntary actions. It splits into:
    - Sympathetic Division: Prepares the body for emergencies.
    - Parasympathetic Division: Calms the body post-emergency.

Definition: The endocrine system is the body’s "slow" chemical communication system, consisting of glands that release hormones into the bloodstream.
Key Components:
- Pituitary Gland: The master gland controlling other endocrine glands.
- Hormones: Chemicals that influence various bodily functions including mood and metabolism.
Interaction: The hypothalamus regulates the pituitary and influences hormone release, highlighting close interaction with the nervous system.

Techniques:
- EEG: Monitors brain electrical activity.
- PET Scan: Visualizes brain activity based on glucose metabolism.
- MRI and fMRI: Provide images of brain structure and function.

Brainstem: Responsible for automatic survival functions like breathing.
Thalamus: Acts as the brain's sensory switchboard, relaying sensory input to appropriate areas.
Cerebellum: Coordinates voluntary movements and processes sensory information.

Components:
- Amygdala: Involved in emotion regulation (fear and aggression).
- Hypothalamus: Regulates homeostatic functions and pleasure centers.

Cortex Composition: Made of interconnected neural cells with specialized functions. Has four lobes:
1. Frontal Lobes: Involved in decision making and planning.
2. Parietal Lobes: Processes sensory input for touch and body position.
3. Occipital Lobes: Houses the visual cortex for processing visual information.
4. Temporal Lobes: Contains the auditory cortex for sound processing.

Most of the cortex is dedicated to association areas that integrate information from different modalities, facilitating higher-level functions like learning and memory.

Plasticity: The brain’s capacity to reorganize itself and form new connections after injury.
Neurogenesis: Development of new neurons, influenced by various factors including environment and activity, especially evident in children.

Split-Brain Research: Highlights the differing functions of the brain’s left (verbal and analytical) and right (spatial and emotional) hemispheres.
Impact of Handedness: Generally, right-handers show left hemisphere dominance for language, while left-handed individuals exhibit more variability in hemispheric dominance.