Week 1: Neuroanatomy - Structure Drives Function Flashcards
What does the nervous system do?
Responsible for:
- Sensory perception
- Cognitive functions
- Motor functions
- Autonomic/Involuntary regulatory functions
Evolution of the brain: The Triune Brain Theory
The Triune Brain Theory states that the human brain is composed of 3 brains evolved over, but from an evolutionary stand-point it doesn’t really make sense
The 3 brains are:
- Central core/Reptilian brain
- Limbic/Paleomammalian brain
- Cerebral cortex/Neomammalian brain
Central Core/Reptillian brain
- Controls behavourial patterns that are repeated + not developed
- Responsible for breathing, arousal, sleep + heart rate
Limbic/Paleomammalian brain
- Limbic system develops emotional system distinguishing the agreeable/disagreeable
- Development that survival is dependent on the avoidance of pain + repetition of pleasure
Cerebral cortex/Neomammalian brain
- Develops knowledge from sight, sound + touch
- Allows higher cognition + emotional function
Cells in nervous tissue
- Neurons
+ Generates + transmits impulses, which are both electrical + chemical
+ 10^11 neurones per brain in humans
+ All neurons are generators + receivors - Neuroglia
+ Provides supportive connective tissue
+ 10^12 neuroglia in humans
Observational methods of neurons
- By histological means:
+ Golgi method: Randomly stains dendrites, soma + axons, this randomness allows contrast
+ Nissl stains: Identifies Nissl substance + shape of cell bodies + proximal dendrites
+ Weigert method: Ferric chloride + haemotoxylin stain, tracks myelinated fibres. Myelin stains deep blue, degenerated portions stain light yellow
Methods to determine brain function
- Examination of cellular organisation of brain
- Remove any parts + identify any effect of ablation
- Examine humans who have suffered brain damage
- Stiumlate brain with specific task, then record brain activity via EEG + fMRI
Brodmann Brain Theory
- Neuronal density + placement correlates to function, where different corticol areas have different functions
- Humans + non-human primates have a total of 52 unique areas, humans have 44 unique areas
- Areas 12-16 + 48-51 are in non-human primates but not in humans
Cerebral cortex
Comprised of:
- Cerebrum
- Cerebral cortex
- Cerebral medulla
- Corpus callosum - The 2 hemispheres connected via this pathway
The 4 lobes of the cerebral cortex
- The 4 lobes are named after the skull bones providing protection
+ Frontal
+ Parietal
+ Occipital
+ Temporal
Frontal lobe
- Functions:
+ Regulating movement
+ Memory formation
+ Emotions
+ Decision making/reasoning
+ Personality
Frontal lobe defects
- Loss of simple movement of various body parts (paralysis)
- Inability to plan a sequence of complex movements
- Loss of spontaneity with others
- Loss of flexibility in thinking
- Persistence of a single thought
- Inability to focus on a task
- Mood changes
- Changes in social behaviour + personality
- Inability to express language, comprehend speech, decreased ability to spread + form words
Parietal lobe
- Functions:
+ Senses + integrates sensation
+ Spatial awareness + perception + proprioperception
Parietal lobe defects
- Lack of awareness of own body parts with respect to space
- Inability to focus visual attention
- Difficult with hand eye coordination
- Inability to atend to more than 1 object at a time
- Inability to locate words during writing (Agraphia)
- Inability to name an object (Anomia)
- Problems with reading (Alexia)
- Difficulty in drawing objects
- Difficulting in telling left from right
- Problems with mathematics (Dyscalculia)
