The Peripheral Nervous System

The Peripheral Nervous System (PNS) consists of all nerves outside the Central Nervous System (CNS). Its primary function is to relay nerve impulses from the CNS to the rest of the body and back again. The PNS is divided into two main branches:

1. Somatic Nervous System: This system is responsible for voluntary actions and conscious control.

Definition: The somatic nervous system consists of nerves emerging directly from the brain and spinal cord, containing sensory and motor neurons.

2. Autonomic Nervous System: This system regulates involuntary actions and is further divided into two branches:

   a. Sympathetic Nervous System (SNS): Responsible for the "fight or flight" response. b. Parasympathetic Nervous System (PNS): Relaxes the body after the fight or flight response.

Highlight: The sympathetic nervous system and parasympathetic nervous system often work on the same organs but have opposite effects, maintaining balance in the body.

Understanding the structure and function of neurons is crucial in biopsychology A level Psychology AQA. Neurons are specialized cells that transmit nerve impulses. They consist of:

• Dendrites: Receive signals from other neurons
• Cell body: Processes the signals
• Axon: Transmits the impulse to other neurons or target cells
• Myelin sheath: Allows nerve impulses to transmit quicker along the axon

Vocabulary: Synaptic transmission is the process by which signals are transmitted between neurons across a synapse using neurotransmitters.

Synaptic transmission occurs when an electrical impulse reaches the pre-synaptic terminal, triggering the release of neurotransmitters. These chemicals diffuse across the synaptic gap and bind to receptors on the post-synaptic neuron, converting the chemical signal back to an electrical impulse.

The Endocrine System

The endocrine system is a network of glands that manufacture and secrete hormones into the bloodstream. This system works in conjunction with the nervous system to regulate various bodily functions. Understanding the endocrine system is crucial for AQA A level Psychology Biopsychology specification.

Definition: The endocrine system is a collection of glands that produce hormones regulating metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things.

Key components of the endocrine system include:

1. Adrenal Glands:
   • Located on top of the kidneys
   • Consist of two parts: adrenal cortex (outer) and adrenal medulla (inner)
   • Produce hormones such as cortisol, adrenaline, and noradrenaline

Example: During stress, the adrenal glands release cortisol, which helps regulate bodily functions, and adrenaline, which increases heart rate and blood flow to muscles and the brain.

2. Pituitary Gland:
   • Located below the hypothalamus in the brain
   • Often called the "master gland" as it controls other glands
   • Releases hormones that stimulate other endocrine glands

The endocrine system plays a crucial role in the body's stress response through two main pathways:

1. Sympathetic-Adrenal-Medullary (SAM) System:

   • Activated by the sympathetic branch of the autonomic nervous system
   • Stimulates the adrenal medulla to release adrenaline and noradrenaline
   • Prepares the body for "fight or flight" response

2. Hypothalamic-Pituitary-Adrenal (HPA) Axis:

   • Activated by the hypothalamus in response to stress
   • Stimulates the pituitary gland to release ACTH
   • ACTH then stimulates the adrenal cortex to release glucocorticoids

Highlight: Understanding the functions of the endocrine system is essential for answering questions like "Explain the function of the endocrine system (4 marks)" in AQA Psychology biopsychology exams.

Localization and Lateralization of Brain Function

The study of brain localization and lateralization is a crucial aspect of biopsychology Psychology A Level. It focuses on understanding how different parts of the brain are associated with specific functions and how the two hemispheres of the brain specialize in different tasks.

Definition: Localization refers to the idea that specific cognitive functions are associated with particular areas of the brain, while lateralization describes how certain functions are more dominant in one hemisphere than the other.

Key points in the study of brain localization and lateralization include:

1. Localization vs. Holistic Theory:

   • The case of Phineas Gage provided early evidence for localization of function
   • Broca and Wernicke discovered specific areas of the brain associated with language production and comprehension

2. Cortical Specialization:

   • Different parts of the brain perform different tasks and are involved with different parts of the body
   • Broca's area is associated with speech production
   • Wernicke's area is linked to speech comprehension

3. Hemispheric Specialization:

   • Each hemisphere has control over particular functions (lateralization)
   • The hemispheres are contralateral: the left hemisphere controls the right side of the body, and vice versa

4. Brain Lobes and Their Functions:

   • Frontal lobe: Motor area, controls voluntary movements
   • Parietal lobe: Somatosensory area, processes sensory information
   • Occipital lobe: Visual area, processes visual information
   • Temporal lobe: Auditory area, processes auditory information and contains Wernicke's area

Example: Damage to Broca's area in the frontal lobe can result in Broca's aphasia, characterized by slow speech and lack of fluency, while damage to Wernicke's area in the temporal lobe can lead to Wernicke's aphasia, where patients produce nonsensical words.

Language Areas of the Brain and Split-Brain Research

The study of language areas in the brain and split-brain research are important topics in AQA A level Psychology biopsychology revision notes. These areas of study provide crucial insights into brain function and hemispheric specialization.

Language Areas of the Brain:

1. Left Hemisphere Dominance:
   • The left side of the brain is typically dominant for language processing in most people
   • Broca's area (frontal lobe): Responsible for speech production
   • Wernicke's area (temporal lobe): Involved in speech comprehension

Highlight: Understanding the language areas of the brain is crucial for answering questions about brain function in AQA A level Psychology biopsychology exam questions.

2. Effects of Damage:
   • Damage to Broca's area can result in Broca's aphasia, characterized by slow, non-fluent speech
   • Damage to Wernicke's area can lead to Wernicke's aphasia, where patients produce fluent but nonsensical speech

Split-Brain Research:

Sperry and Gazzaniga's $1967$ research on split-brain patients has been instrumental in understanding hemispheric specialization.

Definition: Split-brain patients are individuals who have had their corpus callosum (the main connection between the two hemispheres) surgically severed, usually as a treatment for severe epilepsy.

Key aspects of split-brain research:

1. Methodology:

   • Images or words are presented to either the left or right visual field of split-brain patients
   • Information presented to one hemisphere is not transferred to the other due to the severed corpus callosum

2. Types of Tasks:

   • Visual tasks: Describing what is seen in each visual field
   • Tactile tasks: Identifying objects by touch without visual input
   • Drawing tasks: Drawing objects presented to each hemisphere

3. Findings:

   • Demonstrated that each hemisphere has specialized functions
   • Provided evidence for the lateralization of language in the left hemisphere
   • Showed that the right hemisphere has some language capabilities, particularly in comprehension

Example: In a split-brain patient, a word presented to the right visual field (left hemisphere) can be easily read aloud, while a word presented to the left visual field (right hemisphere) cannot be verbalized but can be identified by selecting an associated object.

Understanding split-brain research is crucial for grasping the concept of hemispheric specialization in Biopsychology A level AQA simply Psychology.

Language Areas and Split Brain Research

Research into brain function has revealed specialized areas for language processing and demonstrated the unique capabilities of each hemisphere through split-brain studies.

Definition: Aphasia refers to language impairment resulting from brain damage.

Example: Sperry and Gazzaniga's split-brain research showed how information processing differs between hemispheres when the corpus callosum is severed.

Highlight: Language processing primarily occurs in the left hemisphere, with specific areas dedicated to production and comprehension.

Research Findings and Implications

The final section synthesizes key research findings and their implications for understanding brain function and behavior.

Highlight: Split-brain research has demonstrated the specialized nature of hemispheric functions while also showing the brain's remarkable adaptability.

Example: Patients with split brains show distinct responses when information is presented to different visual fields, indicating hemispheric specialization.

Page 7: Post-Mortem Studies and Biological Rhythms

The page covers brain examination techniques and biological rhythm patterns.

Definition: Circadian rhythms are 24-hour cycles that regulate sleep-wake patterns.

Example: Siffre's cave study demonstrated the persistence of regular sleep schedules without external time cues.

Highlight: Infradian rhythms, like the menstrual cycle, last longer than 24 hours.

The Nervous System

The nervous system is a specialized network of cells that serves as our primary internal communication system. It plays a crucial role in collecting, processing, and responding to information from our environment, as well as coordinating the functions of cells and organs.

Definition: The nervous system is a complex network of neurons that transmits signals between different parts of the body, controlling various physiological and psychological processes.

The nervous system is divided into two main parts:

1. Central Nervous System (CNS): This includes the brain and spinal cord.

2. Peripheral Nervous System (PNS): This comprises all nerves outside the CNS.

Highlight: Understanding the divisions of the nervous system is crucial for AQA A level Psychology biopsychology exam questions.

The brain, a key component of the CNS, consists of several important parts:

• Cerebrum: The largest part, responsible for speech production and processing visual images.
• Cerebellum: Controls motor skills and balance.
• Diencephalon: Contains the thalamus and hypothalamus, which relay sensory information and regulate body temperature.
• Brain stem: Regulates essential life functions.

The spinal cord, another vital part of the CNS, relays information between the brain and the rest of the body. It is connected to specific muscles and glands via spinal nerves, which contain circuits that perform simple reflexes.

Example: A simple reflex action, like pulling your hand away from a hot surface, is controlled by circuits in the spinal cord without involving the brain.