Lecture 4 - Neurophysiology Flashcards
What is the basic “plan” established?
Embryonically
What happens by the middle of the 4th week after conception?
3 distinct swellings are evident at the anterior end of the neural tube, which is going to form the brain
What are the three primary vesicles?
Prosencephalon (forebrain), Mesencephalon (midbrain), Rhombencephalon (hindbrain)
What happens during week 5?
These areas become modified to form 5 regions
What does Prosencephalon (forebrain) become?
Telencephalon, Diencephalon
What does Mesencephalon (midbrain) become?
Mesencephalon
What does Rhombencephalon (hindbrain) become?
Metencephalon and Myelencephalon
What is a Hemorraghic stroke?
Blood leaks into brain tissue
What is a Ischemic stroke?
Clot stops blood supply to an area of the brain
What do the midbrain and hindbrain contain?
Many relay centres for sensory and motor pathways, and are particularly important in the brains control of skeletal movements
What does the Telecephalon and Diencephalon contain?
The forebrain (thalamus + hypothalamus)
What does the cerebrum consist of?
The right and left hemispheres, connected internally by the corpus callous. Performs most of what re considered to be higher functions of the brain
What are the four lobes in the cerebrum?
Occipital lobe, temporal lobe, frontal lobe, Parietal lobe
What does the frontal lobe do?
Motor control
What does the occipital lobe do?
Vision, and co-ordination of eye movements
What does the parietal lobe do?
Perception of somatesthethic sensation - sensation arising from cutaneous, muscle, tendon and joint receptors.
What does the temporal lobe do?
Interpretation and association of auditory and visual information
What is the Insula?
A region buried within the lateral sulcus - the division between the frontal and temporal lobes.
What is the insula implicated in?
Encoding memory, integration of sensory information with visceral responses. Receives olfactory, gustatory, auditory, and somatosensory (mainly pain) information.
What is Cerebral Lateralization?
Each cerebral hemisphere receives different input, but the two hemispheres communicate with each other via the corpus callosum
When has the corpus callosum been cut?
Been surgically cut in some people with severe epilepsy as a way of alleviating their symptoms
What did specifically designed experiments reveal?
That each hemisphere is good at certain types tasks and poor at others
What do the spheres lead to?
“Handedness”
What does damage to the right?
Difficulty with spacial concepts, maps
What does damage to the left?
Severe speech problems, though interestingly may leave the ability to sing unaffected
What is “handlessness”?
Applicable to ~97% of people.
What do SSRI’s do?
Allow serotonin to hang out in the synapse longer
Describe the events of Neurotransmitters, SSRIs and mood disorders?
1.) Message is sent across synaptic gap
2.) Message is received; excess seratonin molecules are reabsorbed by sending neurons
3.) Prozac partially blocks normal reuptake of the neurotransmitter serotonin; excess serotonin in synapse enhances its midd-lifting effect
Who is Kim Peek?
He has no corpus callosum and can remember every page he reads of over 9000 books
What do 68% of the population have an IQ distribution of?
Between 85 and 115
What is the cerebral cortex?
Sheet of grey matter tissue that covers the cerebrum (and cerebellum), divided into left and right hemispheres. Especially important in emotion and memory
What happens to people who have damage to the orbitofrontal area of the prefrontal cortex?
Experience severe impulsive behaviour verging on sociopathic
What is the Thalamus?
Relay centre through which all sensory information (except smell) passes on the way to the cerebrum
- Promotes alertness and causes arousal from sleep in response to any sufficiently strong sensory stimulus
What is the Epithalamus?
Dorsal segment, contains the pineal gland, which secretes melatonin (helps maintain circadian rhythms)
How many parts of the diencephalon is the thalamus?
4/5ths
What is the Epithalamus of the Diencephalon?
The dorsal segment, also contains the pineal gland which secretes the hormone melatonin to help regulate circadian rhythms
Where does the Hypothalamus sit above?
The optic chiasm
What part of the diencephalon is the hypothalamus?
The most inferior portion - site of master circadian rhythm clock (superchiasmatic nucleus)
What does the hypothalamus regulate?
“Daily” body processes such as
- Hunger, thirst, regulation of body temperature
- Hormone secretion from the pituitary gland
- Contributes to the regulation of wake and sleep
What does the midbrain and hindbrain contain?
Many relay centres for sensory and motor pathways, and are particularly important in the brain’s control of skeletal muscles
Where are cell bodies of dopaminergic neurons highly concentrated in?
The midbrain
What does the midbrain have?
2 systems of dopaminergic neurons that project to other areas of the brain
What is the first system?
Nigrostriatal dopamine system, involved in motor control
What is Parkinson’s disease caused by?
The degeneration of the dopaminergic neurons in the Substantia nigra
What is the second system?
The mesolimbic system, involved in emotional reward
What do alcohol, amphetamines, cocaine, marijuana and morphine promote?
The activity of these dopaminergic neurons and plays a role in addiction
What can overactivity in the mesolimbic system cause?
Schizophrenia
What percentage of people get schizophrenia?
40% of men, and 23% of women and the condition is tyowially manifested before the age of 19
What does the hindbrain consist of?
The cerebellum
What is the cerebellum?
The 2nd largest structure of the brain with over 50 million neurons and grey and white matter
What does the cerebellum do?
Monitors and refines motor activity initiated elsewhere
Where does the cerebellum receive input?
From proprioceptors (joint, tendon, muscle receptors) and together with signals from the motor areas of the cerebral cortex, it participates in coordination of movement
What is another component of the hindbrain?
The medulla
What passes through the medulla?
All ascending and descending fiber tracts providing communication between spinal cord and brain must pass through the medulla
Why must it pass through the medulla?
It is required for regulation of breathing, CV responses (vital senses)
What is Attention and Awarness?
Mental process in which concentrate in a specific object, issue or activity and exclude other environmental stimuli
What does Autism affect?
Speech, motor skill and social interaction
What does the Courchesne Theory of Overstimulation suggest?
Autistic children can seem antisocial because they shun external stimulation, since the cerebellum cannot take it
Why do children with Autism get stuck in repetitive behaviour?
Because it is “calming” the easily over stimulated brain
What is Asperger syndrome?
Hyper focus, mild movement disorder, lack of social cues
What is Pervasive Developmental Disorder?
Some range of the same things
