Intro 1-Biological Psychology Flashcards
What was Aristotle’s argument?
That the heart, rather than the brain, was the centre of the mind
What were some of the reasons behind Aristotles argument?
All animals have a heart but not all have a brain eg invertebrates have sensations but no brain. Also the heart is sensitive to touch, unlike the brain
What was Descartes view?
Tried to explain the brain in terms of machines. Also spoke about dualism
What is dualism?
The philosophical position that behaviour is controlled by two entities; the mind and the body
What was Gall’s view?
Brain is an organ of the mind which distinct faculties. The size of the brain measures the power, and the shape of the brain is determined by development of various organs
What is phrenology?
As the skull takes shape from brain, surface of skull can be read as an accurate index of psychological aptitudes and tendencies
What tool was used in phrenology?
Lavery’s Electric Phrenometer
What was Golgi’s contribution to the understanding of the brain?
Using his technique of silver staining he discovered the brain was a large network of interconnected tubes, meaning it would be misleading to think about functional localisation
Who disagreed with Golgi, and why?
Santiago Roman y Cajal later discovered, using a similar technique, that nerve cells are actually discrete entities
What did Brodmann discover?
That cells are grouped in areas, and these areas have different functions
What did Kleist do?
Comprehensive functional mapping of cerebral cortex using case notes from WW1 head wound casualties, and discovered that phrenologists’ language areas differ from Broca and Wernicke’s area
What study did Bailey and Von Bonin do?
Cortico-cortical connexions in chimpanzees found the brain is an interconnected network
What are the ways of studying the brain?
Cytoarchitecture, neuropsychology, imaging techniques, listening techniques, EEG (and event related potentials), near infra-red spectroscopy, direct brain stimulation, transcranial magnetic stimulation
What is cytoarchitecture?
Study of cellular composition of central nervous system’s tissues under the microscope, to discover connectivity and anatomical function
How can neuropsychology be used to study the brain?
Eg Phineas Gage where the brain lesions changed personality, decision making and sense of time
What is a negative point of neuropsychology?
Have to wait for the patient to die to discover function and damage to brain areas
How can imaging techniques be used to study the brain?
MRI studies brain anatomy, fMRI studies brain function (correlation not causation), subtraction method
How can listening techniques be used to study the brain?
Single cell recordings, as with Hubel and Wiesel’s study
What is near infra-red spectroscopy?
Fibre optic cables and sensitive detectors used. Reflections as light bounces off cortex. Heightened activity among neurons increases scattering. Light into 3cm in cortex with spatial specificity of 0.5cm with m5 resolution
What did D’Arsonval and Thompson do?
Contributed to the history of magnetic stimulation of the nervous system. Early attempts to stimulate the brain using a magnetic field
What is the neuronal membrane?
Surrounds every cell in the body. It is intracellular and extracellular
What is the phospholipid bilayer?
It contains ion pumps and channels. Ion movement across the membrane causes electrical signals which affects the ion channels which can either be resting (open), voltage gated, ligand gated or mechanically gated
What are the ions in the intra/extracellular fluid?
Sodium (Na+), Potassium (K+), Chloride (Cl-), and large negative ions (A-)
What forces cause the movement of ions in and out of the cell?
Concentration (high to low density) (Diffusion), and electrical (negative to positive) (balance)
What happens in the membrane at rest?
Sodium ion channels are closed so sodium is free to move across the membrane. Some potassium ion channels are always open. Neuron has more positive ions outside cell so cell is negatively charged. Na/K pump causes imbalance as always pushes three positive sodium out and two positive potassium in
What is the resting membrane potential?
At rest the neuron is negatively charged at -65mv
How do action potentials occur?
Equilibrium is upset by stimulation. If large enough the resting potential becomes an action potential which is generated at the axon hillock if net charge is above the threshold of -50mv, and it is then propagated down the axon
How is sodium linked to the rise of the action potential?
Changes in electrical activity/action potential due to ion movement. Cell stimulated above threshold so sodium ion channels open. Sodium attracted in the cell due to more Na+ outside. Also because cell is negatively charged. This influx causes the cell to become more positive
How is potassium linked to the fall of the action potential?
The cell is positively charged when action potential reaches peak. Electrical force changes and potassium is attracted outside cell (which is negative). Still more potassium in the cell than out, so concentration force also forces potassium out of the cell
What is a nerve impulse?
Action potential quickly propagated down the axon to the pre-synaptic terminals. Some axons are covered in myelin, which is produced by glial cells (oligodendrocytes and Schwann cells)
What is the difference between myelinated and non-myelinated axons?
Myelinated axons conduct action potentials quicker than those without, by saltatory conduction
What is the refractory period?
Action potentials are all or nothing events. One cannot occur until the previous one has finished. The strength of the stimulus is denoted by increasing firing rate. Neurons can fire many action potentials per second
How are synapses related to action potentials?
Action potential reaches presynaptic terminal, then neurotransmitter is released into the synapse. This can have an excitatory or inhibitory effect
How does excitation and inhibition affect the nervous system?
The nervous system works through excitation and inhibition. The balance however breaks down in conditions such as epilepsy where neurons are too active causing seizures (uncontrollable patterns of electrical activity). The correct balance of excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP) is needed for the proper working of the nervous system
What are the three factors that determine the electrical activity of the cell?
How well ions move across the cell membrane, why they move across, and when they move across
What are synapses formed by?
The termination of an axon from one neuron onto the dendrite of another neuron
WHat are specialised synapes?
They form between neurons and muscles allowing contraction and movement (neuro-muscular junction)
What is ALS?
Amyotrophic lateral sclerosis affects the axons from neurons that activate muscles, located in the spinal cord, gradually restricting movement until it results in death
How are neurotransmitters made/transported?
Made in cell body, packaged into vesicles then transported along axon to presynaptic terminal
How do neurotransmitters work?
Remain dormant until action potential arrives. When it arrives along the synapse it causes calcium ion channels to open (Ca++). Incoming Ca++ binds to synaptic vesicles causing them to release their neurotransmitter into the synapse
What are ionotropic neurotransmitter receptors?
Proteins found on dendrites. Receptors composed of two parts; binds neurotransmitters, and an ion channel. Neurotransmitter binds to receptor, channel opens, allows ions in cell
What are metabotropic neurotransmitter receptors?
Influence ion channels indirectly. Neurotransmitter binds to binding site, subunit detaches causing ion channel to open, allowing ions to pass through. These receptors influence function slower than ionotropic receptors
What is neurotransmitter removal/inactivation?
Neurotransmitters need to be removed after release or prolonged activation can occur, eg blood flow to brain reduced, glutamate not removed from synapse, excitatory response continues, leading to stroke
What is synaptic integration?
Spatial integration of EPSPs and temporal integration of EPSPs
What are some examples of the fact that different neurons have different neurotransmitters?
Glutamate and major excitatory neurotransmitter for learning and memory. GABA and main inhibitory neurotransmitter. Dopamine and movement control and reward circuits. Serotonin-profound effect on mood and anxiety
What is Parkinson’s disease?
Loss of dopaminergic neurons in brain stem
What drug is often used to treat Parkinson’s?
Levo-dopa, which mimics dopamine, temporarily reliving symptoms, however also can cause schizophrenic symptoms as schizophrenia is partly caused by overactivity of dopaminergic pathways
What toxins poison ion channels?
Tetrodotoxin (puffer fish and Na+ channels), scorpions and Na+ channels, wasps/bees and K+ channels, a-latrotoxin (black widow spider and nerve-muscular junction), botulism (excitatory neurotransmitters at neuro-muscular junction), tetanus (inhibitory neurotransmitters at spinal cord)
What toxins block neurotransmitter receptors?
Poisonous plants, venomous animals. Eg a-Bungarotoxin (banded krait snake) blocks neurotransmitter receptors on nerve-muscle junction
How do psychoactive drugs link to neurotransmitter?
Mimic effects of neurotransmitters by binding directly to receptors. LDS and psilocybe mimic srotonin (antagonists). Alcohol affects GABA receptors, increasing inhibitory effect, leading to sedative like effect (also acts as an antagonist blocking glutamate receptors)
What drugs affect the uptake of neurotransmitters?
Cocaine prevents reuptake of dopamine, prolonging arousal effect. Prozac blocks reuptake of serotonin, enhancing effect of felling of well-being
Why do some people become addicted to drugs?
Association between drug taking and reward circuits in the brain. Dopamine is an important component in reward circuits. Many highly addictive drugs activate this system in the brain
How is the nervous system organised?
The nervous system splits into the central nervous system (brain/spinal cord) and the peripheral nervous system (somatic/autonomic-sympathetic/parasympathetic)
What are the surface features of the brain?
Gyri (bumps) and sulci (fissures/grooves)
What is cerebrospinal fluid?
The cushion between the brain and the skull
How is the cerebral cortex organised?
Two hemispheres with four lobes: occipital, parietal, temporal and frontal
What is the cerebral cortex?
Forms layer of nerve cells that cover the outer surface of the brain. The number/variety of neurons varies in different parts of the cerebral cortex. Different regions have different functions
What is beneath the surface of the brain?
The basal ganglia and the limbic system
What is the basal ganglia?
Important in the control of voluntary movement
What is the limbic system?
Important in the navigation in space and memory formation
What is the brainstem?
Composed of nerves that run up from the body into the brain. Used for alertness, and regulates processes. Includes the hindbrain and cerebellum, midbrain, and diencephalon and thalamus, hypothalamus, pituitary
What are cranial nerves?
Part of the somatic nervous system that allow the brain to communicate with muscles and sense organs of the head and neck
What are the 12 cranial nerves?
Olfactory, optic, oculomotor, trochlear (eye movement), trigeminal (chew/facial sensation), abducens (eye movement), facial, auditory vestibular, glossopharyngeal (tongue/pharynx), vagus (heart/blood vessels/viscera), spinal accessory, and hypoglossal (tongue muscles)
How do the cranial nerves work?
Brain communicates with body via spinal cord and cranial nerves. Sensory information is relayed to the brain via the spinal cord and brain sends motor commands via spinal cord to muscles to produce movement. Nerve fibres leave spinal cord through gaps between vertebrae