Welcome to the World of Biopsychology!
Ever wondered why your heart races when you’re scared, or how your brain manages to turn a bunch of squiggles on a page into meaningful words? That is exactly what Biopsychology is all about. We are looking at the "hardware" of the human body—the brain, the nerves, and the hormones—to understand how they create our "software" (our behavior and thoughts). Don't worry if it sounds a bit "sciencey" at first; we will break it down into simple, easy-to-digest pieces.
1. The Divisions of the Nervous System
Think of the Nervous System as the body’s primary communication network. It has two main branches:
A. The Central Nervous System (CNS)
The CNS is the "Control Center." It consists of:
• The Brain: The seat of all conscious awareness.
• The Spinal Cord: An extension of the brain that passes messages to and from the body and connects nerves to the brain. It also handles basic reflexes.
B. The Peripheral Nervous System (PNS)
The PNS consists of all the nerves outside the brain and spinal cord. Its job is to relay messages from the CNS to the rest of the body. It is divided into:
• Somatic Nervous System (SNS): This controls voluntary muscle movements. When you decide to wave at a friend, your SNS is at work.
• Autonomic Nervous System (ANS): This controls involuntary actions (things you don't think about, like your heartbeat or digestion). It has two further sub-divisions:
1. Sympathetic: The "Emergency" state (Fight or Flight).
2. Parasympathetic: The "Relax" state (Rest and Digest).
Key Takeaway: The CNS is the boss (Brain/Spinal Cord), and the PNS is the messenger system that carries out the boss's orders throughout the body.
2. Neurons and Synaptic Transmission
Neurons are specialized nerve cells that move information around the body using electrical and chemical signals.
Three Types of Neurons
1. Sensory Neurons: Carry messages from senses (eyes, skin, etc.) to the CNS. They have long dendrites and short axons.
2. Relay Neurons: These connect sensory neurons to motor neurons or other relay neurons. They are found only in the CNS.
3. Motor Neurons: Carry messages from the CNS to muscles and glands to trigger movement. They have short dendrites and long axons.
Synaptic Transmission: How Neurons Talk
Neurons don't actually touch! There is a tiny gap between them called a synapse.
1. An electrical impulse (action potential) travels down the axon of the neuron.
2. When it reaches the end, it triggers the release of chemicals called neurotransmitters from tiny sacs called vesicles.
3. These chemicals cross the gap and bind to receptor sites on the next neuron.
4. This message is then turned back into an electrical impulse.
Excitation and Inhibition
Neurotransmitters have different "vibes":
• Excitation: Like Adrenaline. It makes the next neuron more likely to fire (the "GO" signal).
• Inhibition: Like Serotonin. It makes the next neuron less likely to fire (the "STOP" signal).
Quick Review: Sensory = Input. Motor = Output. Synapse = The gap where chemicals (neurotransmitters) do the talking.
3. The Endocrine System and Fight or Flight
While the nervous system uses electricity, the Endocrine System uses chemicals called hormones sent through the bloodstream.
Glands and Hormones
• Glands: Organs that produce hormones (e.g., the Pituitary Gland is the "Master Gland" in the brain).
• Hormones: Chemical messengers that travel in the blood to affect distant organs (e.g., Adrenaline).
The Fight or Flight Response
When you face a threat, your body prepares to either fight or run away:
1. The Hypothalamus identifies a threat and sends a signal to the Sympathetic Nervous System.
2. This triggers the Adrenal Medulla to release Adrenaline into the blood.
3. Physical changes occur: Heart rate increases (to pump blood to muscles), breathing speeds up (more oxygen), and digestion stops (to save energy).
4. Once the threat passes, the Parasympathetic Nervous System kicks in to calm you down.
4. Localisation of Function in the Brain
Localisation is the idea that specific parts of the brain do specific jobs. If that part is damaged, that specific function is lost.
Key Areas of the Brain
• Motor Area (Frontal Lobe): Controls voluntary movement. Damage here causes loss of muscle control.
• Somatosensory Area (Parietal Lobe): Processes sensory info like touch and heat.
• Visual Area (Occipital Lobe): Processes what you see.
• Auditory Area (Temporal Lobe): Processes what you hear.
Language Centres (Usually in the Left Hemisphere)
• Broca’s Area: Responsible for speech production. Damage (Broca’s Aphasia) means the person can understand speech but struggles to speak (it's slow and laborious).
• Wernicke’s Area: Responsible for language understanding. Damage (Wernicke’s Aphasia) means the person can speak fluently, but the words make no sense ("word salad").
5. Hemispheric Lateralisation and Split-Brain Research
Hemispheric Lateralisation means the two halves (hemispheres) of our brain aren't identical; they specialize in different things.
The "Left" vs. "Right" Brain
• Left Hemisphere: Controls the right side of the body. It is the "Logic" side (Language, Math).
• Right Hemisphere: Controls the left side of the body. It is the "Creative" side (Facial recognition, Spatial tasks, Music).
Split-Brain Research (Sperry)
Sperry studied patients who had their Corpus Callosum (the bridge between the two halves) cut to treat epilepsy.
• Finding: If a split-brain patient saw a picture of an apple in their right visual field, they could say "Apple" because the info went to the Left hemisphere (the language side).
• Finding: If they saw it in their left visual field, they couldn't say what it was, but they could draw it with their left hand! This proved the hemispheres work separately if the bridge is cut.
Common Mistake to Avoid: Don't say the Right Hemisphere is "stupid." It understands language; it just doesn't have the "voice box" (Broca's Area) to speak it!
6. Plasticity and Functional Recovery
Can the brain change? Yes! This is called Plasticity.
Brain Plasticity
The brain creates new neural pathways and removes old ones based on experience and learning. For example, London taxi drivers have been found to have larger hippocampi (the memory part of the brain) because they have to learn so many routes.
Functional Recovery After Trauma
When the brain is damaged (e.g., by a stroke), it can sometimes "fix" itself by:
• Neuronal Unmasking: Dormant (sleeping) synapses open up to take over the job of damaged ones.
• Axonal Sprouting: Healthy nerve endings grow new branches to connect with other undamaged nerve cells.
• Recruitment of Homologous Areas: The opposite side of the brain takes over the tasks of the damaged side.
Key Takeaway: The brain is "plastic"—it is flexible and can adapt even after injury.
7. Ways of Studying the Brain
How do we know what's happening inside someone's head? Here are the four syllabus methods:
1. fMRI (functional Magnetic Resonance Imaging):
• How: Measures blood flow. Active areas need more oxygen/blood.
• Good: High spatial resolution (shows exactly where things happen).
• Bad: Poor temporal resolution (it's a bit slow to show changes).
2. EEG (Electroencephalogram):
• How: Electrodes on the scalp measure general electrical activity ("brain waves").
• Good: Great for diagnosing sleep disorders or epilepsy.
• Bad: It’s too general—you can't tell exactly where the signal is coming from.
3. ERPs (Event-Related Potentials):
• How: A version of EEG where you filter out background noise to see the brain's response to a specific stimulus (like a sound).
• Good: Very specific timing (high temporal resolution).
• Bad: Difficult to eliminate all "noise" from the data.
4. Post-mortem Examinations:
• How: Looking at a brain after the person has died.
• Good: Allows for deep, physical inspection of the brain tissue.
• Bad: You can't see the brain "in action," and damage found might not be the cause of the person's behavior.
Quick Review Box:
• Where? Use fMRI.
• When? Use ERPs.
• General state? Use EEG.
• Dead? Post-mortem.