Chapter 3: Biological Bases Flashcards
How is the nervous system organized?
Central nervous system Peripheral
Brain Spinal Cord Somatic Autonomic
- Forebrain - Efferent nerves -sympathetic
- Midbrain -Afferent nerves -parasympathetic
-Hindbrain
Which parts of the peripheral nervous system are voluntary and involuntary?
Autonomic = involuntary Somatic = voluntary
What structures make up the peripheral nervous system?
Bundles of nerves (neuron fibres)
What are nerves?
Bundles of neuron fibres (axons) that are routed together in the peripheral nervous system
What is the somatic nervous system?
System made up of nerves that connect to the voluntary skeletal muscles & sensory receptors
-skin, muscles, joints, CNS
What are the nerve fibres used in the somatic nervous system?
CNS periphery
What structures make up the peripheral nervous system?
Bundles of nerves (neuron fibres)
What are nerves?
Bundles of neuron fibres (axons) that are routed together in the peripheral nervous system
What is the somatic nervous system?
System made up of nerves that connect to the voluntary skeletal muscles & sensory receptors
-skin, muscles, joints, CNS
What are the nerve fibres used in the somatic nervous system?
CNS periphery
What is the Autonomic nervous system?
System made up of nerves that connect to the heart, blood vessels, smooth muscles and glands
&
controls involuntary visceral functions
>heart rate, perspiration, etc.
&
mediates physiological arousal from emotions
Who identified fight-or-flight?
Walter Cannon
What are the 2 branches of the autonomic nervous system?
Sympathetic and parasympathetic
What are the ventricles in the brain and how many are there?
Hollow cavities in the brain that are filled with cerebrospinal fluid.
There are 4
What is the central nervous system?
The brain, spinal column and the protecting enclosed sheaths of meninges that bathe the brain and spine in cerebrospinal fluid
What is cerebrospinal fluid?
A fluid that nourishes and cushions the brain and spine
What is the spinal cord?
The spinal cord connects the brain to the rest of the body via the peripheral nervous system and is an extension of the brain that houses bundles of axons
What can disection of the brain show and not show?
- It can show the structure
- It cannot show the function nor the connection between the brain and behaviour
What are the most common brain research methods?
- Electrical recordings (EEG)
- Lesioning
- Electrical stimulation
- Brain imaging
- Transcranial Magnetic Stimulation
What are electrical recordings of the brain and how are they measured?
They record electrical activity in the brain using and Electroencephalograph (EEG)
> a device that monitors electrical activity in the brain over time via electrodes attached to the scalp> brainwaves
>sums & amplifies electrical potentials in brain cells
>research re sleep, consciousness, processing
What is the EEG most commonly used for?
Clinical diagnosis of brain damage and neurological disorders
&
Identifying brain activity patterns relative to specific behaviours
How is lesioning enacted on animals?
-An electrode is inserted into the brain structure and high-frequency current is passed through to burn and disable the structure
> uses a stereotaxic instrument to place the electrode precisely
What is lesioning and how is it applied?
Lesioning involves destroying a piece of the brain as a case study
- therefore brain damaged patients must be used
- therefore lesioning is applied to animal brains to observe specific structures being disabled and impact on behaviour
- invaluable for research on brain function
What is the most famous lesioning case study?
By Milner on H.M.
‘the brain that changed everything’
-portions of brain were removed to aleviate epilepsy
-resulted in Anterograde amnesia where he had a good pre-surgery memory but after had a good short-term memory but was not able to form new long-term memory
What are the cons of using brain-damages patients?
- subjects not plentiful
- location & severity of the damage is uncontrollable
- variations in patient histories cause too many extraneous variables so cause-and-effect cannot be isolated
What is electrical stimulation of the brain (ESB) and how is it applied?
A weak electrical current is sent into the brain structure to stimulate it by using an electrode (stereotaxic)
> the current approximates normal brain signals to activate
ESB is mostly conducted on animals or on humans during brain surgery
What are the pros and cons of TMS?
Prod: circumvents many uncontrolled variables in brain damaged patients
Cons: can’t study deep brain
What is Transcranial Magnetic Stimulation and how is it applied?
-TMS is a new technique that can depress or enhance activity in an area of the brain
- a magnetic coil creates a 2cm magnetic field that stimulates via pulsing which excites neurons in local tissue
> virtual lesions
- investigating therapeutic potential for eating disorders, anxiety and schizophrenia
Meta-analysis is particularly useful with what data?
Imaging data
What is the CT scan?
CT= computerized tomography that is a computer-enhanced x-ray
> multiple images are combined to make a horizontal slice of the brain
> least expensive imaging option
What conditions is the CT linked with revealing?
The association between Schizophrenic disturbance and the enlargement of the brains ventricles
What is the PET scan?
PET = Positron Emission Tomography
- demonstrates brain & behaviour link
- uses radioactively tagged chemicals as markers of blood flow or metabolic activity in the brain & monitors with x-rays to produce a colour coded brain activity map
> FUNCTION
What specifically is a PET scan good for studying?
Neurotransmitter activity
What is an MRI?
MRI = Magnetic Resonance Imaging
- uses magnetic fields, radio waves and computerized enhancement to map brain structures
> better imaging than CT
What are the pros of an MRI?
- 3D image
- better than a CT
- insights into depressive disorders
What is the FMRI?
Functional magnetic resonance imaging
- monitors blood flow and oxygen consumption to identify high activity areas over time
> map activity
What are the benefits of the FMRI?
- It’s exacting
- illustrates function
- illustrates complexity
- good for locked-in patients, same imagery for certain activities
What structures make up the 3 regions of the brain?
Hindbrain- cerebellum, pons, medulla
Midbrain- reticular formation
Forebrain- Thalamus, hypothalamus, limbic system, crerebrum
What structures make up the 3 regions of the brain?
Hindbrain- cerebellum, pons, medulla
Midbrain- reticular formation
Forebrain- Thalamus, hypothalamus, limbic system, crerebrum
What does the medulla do?
Oversees unconscious vital functions > blood circulation > breathing > muscle tone > reflex regulation (sneezing, coughing, salivate)
What does the Pons do?
The pons is a bridge of fibres that is a collection of clusters of cell bodies that are linked to sleep & arousal
> connects brainstem with the cerebellum
What is the Midbrain?
Segment of brainstem between hindbrain and forebrain that is concerned with integrating sensory processes
> vision & hearing
- origin of dopamine-releasing neurons that travel for voluntary movements
What is the Midbrain connection to Parkinson’s?
Degeneration of structure in the midbrain causes a decline in the dopamine synthesis and is causally linked with Parkinson’s
What is the reticular formation?
At the core of the brainstem and contributes to the modulation of muscle reflexes, breathing and pain perception
> sleep and arousal
What is the forebrain?
Largest and most complex region of the brain encompassing multiple structures
- made up of the thalamus, hypothalamus, cerebrum and limbic system*
- core of the forebrain
What is the thalamus and what does it do?
Structure through which ALL SENSORY INFO must pass through (except smell) to get to the cerebral cortex
- ‘way station’ made of soma clusters
- each cluster relays info to part of cortex
What are the 4 Fs of survival drives?
- Fighting
- Fleeing
- Feeding
- Mating
What is the hypothalamus?
Structure near the base of the forebrain involved in regulation of basic biological needs
- controls the autonomic nervous system
- vital link b/w brain & endocrine system
- Regulates survival drives (4Fs)
> hunger, thirst, temperature
What is the Amygdala?
Part of the Limbic System - fear response learning - processing of basic emotional responses - processing of both +/- stimuli > agression
What is the Limbic System?
Loosely connected network of structures located along the border w cerebral cortex and deeper subcortical areas. Includes
- parts of thalamus and hypothalamus
- hippocampus
- amygdala
- other structures
Regulates EMOTION, MEMORY, MOTIVATION & OPTIMISM
> pleasure centres
What is consolidation?
The conversion of information into a durable code
What is the hippocampus?
Part of the limbic system that surrounds the thalamus and is involved in
LEARNING & MEMORY
- memory processes
- consolidation of memories for factual information
- prediction & imagination
Who created the pleasure centre experiment and what was it?
James Olds
- rat would press the lever to stimulate pleasure centre which was supposed to be in reticular formation but was in hypothalamus
> pleasured until collapsed
Where are the self-stimulation centres?
In the Limbic System in the mdeial forebrain bundle that passes through the hypothalamus where it is rich in dopamine-releasing neurons
What is the corpus callosum?
The structure of thick band of fibres that connects the 2 cerebral hemispheres
How is each hemisphere divided?
Into 4 lobes:
- Occipital
- Parietal
- Temporal
- Frontal
What is the occipital lobe?
Lobe @ back of head
- visual signals & processing begins
- houses the Primary Visual Cortex
What is the Parietal Lobe?
In the middle b/w the occipital and frontal lobes on top
- houses the Primary Somatosensory Cortex
> sense of touch
> integrates visual input + body’s position in space
> visual control of reaching
What is the temporal lobe?
Lobe near the temples and below the parietal lobe
- Primary Auditory Cortex
> auditory processing
What is the Frontal Lobe?
The largest lobe at the front of the brain
- Primary Motor Cortex
- Cortex allocation depends on body part diversity & precision of movement
- Prefrontal cortex
What is the Prefrontal Cortex and what does it do?
‘Executive control system’
> monitor, organize, integrate & direct thought processes
- In the front portion of the frontal lobe and accounts for 1/3 of cerebral cortex
- high-order functions
WORKING MEMORY + REASONING BW OBJECTS & EVENTS + DECISION MAKING
What is the Cerebrum and what does it do?
It’s the largest and most complex part of the brain, responsible for
LEARNING, REMEMBERING, THINKING + CONSCIOUSNESS
- outer layer is the cerebral cortex
What is brain plasticity?
Brain’s ability to change structure and function
How does experience link to plasticity?
Experience stimulates plasticity and affects dendritic length, synapse formation and altered metabolic activity
What are neurotransmitters?
How are they stored?
- Chemicals that transmit information from one neuron to another
- They’re stored in synaptic vesicles in the terminal buttons
How are neurotransmitters released?
A vesicle fuses with the membrane of the pre-synaptic cell and its contents spill into the cleft
What happens to the neurotransmitters once they are released?
They diffuse across the cleft to the membrane of the receiving cell and bind at receptor sites with special molecules
Can neurotransmitters be received at all sites?
No, they can only bind to receptor sites that their particular molecular structure fits into
What are post-synaptic potentials?
PSPs- occur when a receptor combines with a neurotransmitter on the receiving cell, causing a voltage change at the receptor site
Do post-synaptic potentials follow the all-or-none law?
No, they are graded
- they vary in size and increase/decrease the probability of a neural impulse in the post-synaptic neuron
> relative to the amount of voltage change
What are the types of post-synaptic potential messages?
- Excitatory: + voltage shift that increases the likelihood that a post-synaptic neuron will fire an action potential
- Inhibitory: - voltage shift that decreases the likelihood that a post-synaptic neuron will fire an action potential
What happens to neurotransmitters after the PSP?
- They are inactivated by enzymes and metabolized
- They are recycled through Reuptake
What is reuptake?
When neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane
What does Temporal Summation mean?
When PSPs add up at the same receptor site of one neuron
What does spatial summation mean?
When PSPs add up via signals from many neurons arriving at the same time to different sites of one neuron
What must neurons do before deciding to fire an impulse?
They must integrate signals which is a balance between excitatory & inhibitory influences
> millions must fire at once
Which neurons are likely to fire at the same time in the neural network?
Those neurons that are wired together fire together
> patterns
What has more influence in sculpting the neural networks than the creation of new synapses?
Pruning or elimination of old synapses
Whose work determined that neurons are linked in complex networks called assemblies to influence behaviour?
Donald Hebb
What are the common neurotransmitters?
- Acetylcholine (Ach)
- Norepinephrine (NE) > monoamine
- Dopamine (DA) > monoamine
- Seratonin > monoamine
- GABA > amino acid
- Glycine > amino acid
- Glutamate > amino acid
- Endorphines