Biopsychology

Welcome to Biopsychology!

Welcome to one of the most exciting parts of your AQA Psychology course! Biopsychology is all about the "hardware" of the human body. We are looking at how our physical structures—like our brain, our genes, and our hormones—actually create our thoughts and behaviors. Don't worry if the science feels a bit heavy at first; we will break it down into simple, manageable chunks with plenty of analogies to help it stick!

1. The Divisions of the Nervous System

Think of your nervous system as a giant communication network, like the internet. Its job is to collect information, make decisions, and send out instructions.

The Central Nervous System (CNS)

The CNS consists of the brain and the spinal cord. This is the "Control Center." The brain makes sense of the world, while the spinal cord is like a high-speed data cable that passes messages between the brain and the rest of the body.

The Peripheral Nervous System (PNS)

The PNS sends information from the outside world to your CNS and carries messages from the CNS to your muscles and glands. It has two main parts:

• Somatic Nervous System: This controls voluntary movements (like waving your hand). It uses sensory neurons to send info to the brain and motor neurons to make muscles move.
• Autonomic Nervous System (ANS): This controls involuntary actions (things you don't think about, like your heart beating or digesting food). The ANS is further split into two:

1. Sympathetic State: The "Emergency" mode. It gets you ready for action (increases heart rate).
2. Parasympathetic State: The "Relax" mode. It calms you down after a scare (decreases heart rate).

Quick Review: The CNS is the brain/spine. The PNS is everything else. The Autonomic system is automatic!

2. Neurons and Synaptic Transmission

Neurons are specialized cells that carry electrical signals. You need to know three types:

• Sensory Neurons: These carry messages from senses to the CNS. They have long dendrites and short axons.
• Relay Neurons: These connect sensory neurons to motor neurons. They stay inside the CNS.
• Motor Neurons: These carry messages from the CNS to muscles/glands to make them move.

How do they talk to each other? (Synaptic Transmission)

Neurons don't actually touch! There is a tiny gap between them called a synapse. When an electrical impulse reaches the end of a neuron, it triggers the release of chemicals called neurotransmitters. These float across the gap and bind to receptors on the next neuron, like a key fitting into a lock.

Excitation vs. Inhibition:
• Excitation: Like a "Green Light." It makes the next neuron more likely to fire (e.g., Adrenaline).
• Inhibition: Like a "Red Light." It makes the next neuron less likely to fire (e.g., Serotonin).

Mnemonic: S-R-M (Sensory, Relay, Motor). Think of a relay race where the baton is passed between them!

3. The Endocrine System and Fight or Flight

The Endocrine System is a network of glands that secrete hormones into the bloodstream. While the nervous system is like an "Instant Message," the endocrine system is more like "Snail Mail"—it’s slower but the effects last longer.

The Fight or Flight Response

When you face a threat, your Hypothalamus triggers the Sympathetic branch of your ANS. Your Adrenal Medulla releases the hormone Adrenaline into your blood.

What happens?
• Increased heart rate (to pump blood to muscles).
• Faster breathing (to get more oxygen).
• Dilated pupils (to see better).
• Digestion stops (to save energy for the "fight").

Once the threat is gone, the Parasympathetic branch kicks in to return your body to its normal resting state (Rest and Digest).

4. Localisation of Function in the Brain

Localisation simply means that specific parts of the brain do specific jobs. Here are the "Zones" you need to know:

• Motor Area: In the Frontal Lobe. Controls voluntary movement.
• Somatosensory Area: In the Parietal Lobe. Processes sensory info like touch and heat.
• Visual Area: In the Occipital Lobe (back of the head). Processes what you see.
• Auditory Area: In the Temporal Lobe. Processes what you hear.
• Broca’s Area: Usually in the left frontal lobe. Responsible for speech production. (Think: Broca = Broken speech if damaged).
• Wernicke’s Area: Usually in the left temporal lobe. Responsible for language understanding. (Think: "Wernicke... What?" if you can't understand what someone says).

Did you know? Phineas Gage is the most famous case study here. A metal rod went through his frontal lobe, and while he survived, his personality completely changed, proving that the frontal lobe is linked to mood and personality!

5. Lateralisation and Plasticity

Hemispheric Lateralisation

The brain has two halves (hemispheres). Lateralisation means some functions are only in one half. For most people, language is in the Left Hemisphere. Visual-spatial tasks are often in the Right Hemisphere.

Split-Brain Research: Sperry studied people who had their Corpus Callosum (the bridge between halves) cut to treat epilepsy. He found that if a patient saw an object in their right visual field, they could say what it was (because it went to the language-heavy Left brain). If they saw it in their left visual field, they couldn't name it, but they could draw it with their left hand!

Plasticity and Functional Recovery

Plasticity is the brain's ability to change and adapt as a result of experience. Like a muscle, the more you use a certain pathway, the stronger it gets. Synaptic Pruning is when the brain gets rid of pathways it doesn't use anymore.

Functional Recovery: This is when the brain "rewires" itself after trauma (like a stroke). Other parts of the brain take over the jobs of the damaged parts. This happens through axonal sprouting (growing new nerve endings) and recruitment of homologous areas (using similar areas on the opposite side of the brain).

6. Ways of Studying the Brain

How do we actually see what's going on in there? You need to compare these four:

• fMRI: Detects changes in blood oxygenation. If a part of the brain is active, it needs more blood. Pro: High spatial resolution (detailed picture). Con: Poor temporal resolution (5-second delay).
• EEG: Measures electrical activity via electrodes on the scalp. Pro: Great for seeing brain waves in real-time (sleep studies). Con: Can't tell exactly where the signal is coming from.
• ERPs: A more specific version of EEG where we filter out background noise to see the brain's response to a specific stimulus. Pro: Very specific timing. Con: Hard to eliminate all outside interference.
• Post-mortem: Examining the brain after death. Pro: Allows for deep, physical inspection. Con: You can't see the brain "in action," and damage found might not be the cause of the behavior.

7. Biological Rhythms

Our bodies have internal "clocks" that govern our behavior. There are three types:

• Circadian Rhythms: Last about 24 hours (e.g., the Sleep/Wake cycle).
• Infradian Rhythms: Last longer than 24 hours (e.g., the Menstrual cycle or Seasonal Affective Disorder).
• Ultradian Rhythms: Last less than 24 hours (e.g., the stages of sleep, which repeat every 90 minutes).

How are they controlled?

Endogenous Pacemakers: These are internal body clocks. The most important one is the SCN (Suprachiasmatic Nucleus) in the hypothalamus, which controls the release of melatonin.
Exogenous Zeitgebers: These are external cues that reset our clocks. The most powerful one is Light. Social cues (like mealtimes) also help.

Common Mistake: Don't confuse the two! Endogenous is Internal. Exogenous is External.

Key Takeaway: Biopsychology shows us that we aren't just "minds"—we are biological machines! Understanding the nervous system, brain structures, and body clocks helps us explain why humans behave the way they do.