Anatomy of Neural Circuits Flashcards
how could you section the brain?
- sliced across 2 planes (front to back) can see 2 hemispheres
- along the horizontal axis (2 parts of the brain are symmetrical)
- sideways (not symmetrical)
what would a mid sagittal section look like?
- forebrain compromises of cerebral hemispheres and diencephalon (CNS)
- lower hind bran structures are the pons, medulla and cerebellum (CNS)
- motor nerves (PNS)
what is the diencephalon?
thalamus and hypothalamus
how does an MRI work?
- nuclei of hydrogen atoms act as spinning magnets
- strong magnetic field to align protons
- burst of radio waves temporarily flips the protons out of alignment (return to state and emit energy)
- energy is detected
- hydrogen in different types of tissue have slightly different realignment rates
what does the brain stem include?
the medulla, midbrain and bons
what is the brain stem?
- evolutionary oldest brain regions
what is the function of the brain stem?
- automic
- digestion, respiration, heart rate, blood pressure, swallowing
- site of entry for sensory information
- mediates arousal
what does the pons do?
relays information from the cerebral cortex to the cerebellum
what is the function of the cerebellum?
- recieves input of motor task to be performed and progress of ongoing skills
- provides corrective skills and fine tunes movement
- learning of motor skills
- controls fine movement
what is the structure of the cerebellum?
- organised into 3 layers of cells
1. granular layer
2. purkinje layer
3. molecular layer
what is the cerebellum?
10% of brain volume but 50% of neurons
- evolutionary ancient
how can the cerebellums function be tested?
activation of the cerebellum during a bilateral finger tapping task which can be visualized by MRI –> fMRI activity superimposed
what does fMRI stand for?
functional MRI
what is fMRI?
- depends on the fact that haemoglobin in blood distorts MRI properties of the spinning H atoms
- amount of distortion depends on whether haemoglobin is carrying oxygen or not
- measures areas where there are higher levels of oxygenated blood in the brain
- increase blood flow to parts of the brain that are active
what is the cerbral cortex?
- most evolved brain structure (humans have a large cerebral cortex)
- heavily wrinkled to allow lots of neurons
what is the structure of the cerebral cortex?
- 4 different lobes: frontal lobe, parietal lobe, occipital lobe, temporal lobe
- organised into (6) cell layers which organise inputs and outputs
- neurons of the brain are organised into circuits
what is the function of the frontal lobe?
planning future action (pre-frontal cortex)
control of movement (motor cortex)
what is the function of the parietal lobe?
somatic sensation
touch, pain and pressure
what is the function of the occipital lobe?
vision
what is the function of the temporal lobe?
hearing
deep lying structures eg the hippocampus - learning and memory
emotion - amygdala
- regulating motor performance - basal ganglia
what is the function of the cerebral cortex?
- responsible for high order functions
- know more about neurons involved in sensory and motor than in processing language, memory or emotion
why are neurons organsied into circuits?
so that the neurons for one particular function are in one neural system
what diseases do problems in the basal ganglia lead to?
parkinsons or huntigdons disease
what does emotion influence?
motivation behaviours
what are the key components of emotion?
- physical sensation
2. conscious feeling
what structures are responsible for physical sensation?
- Peripheral, autonomic, endocrine and skelomotor response
- Amygdala, hypothalamus and brain stem
what ares structures are responsible for conscious feeling/perception?
- Cortical structures: orbital and medial frontal lobes (prefrontal cortex)
what is function of the amygdala?
- required for fearful and pleasurable response
- generates memories associated with emotional experiences
- recieves information from the thalamus and sensory cortex
which structures does the amygdala work with for physical manifestation?
thalamus and brain stem
which structure does the amygdala work with for conscious feeling?
pre-frontal cortex
which structure does the amygdala work with for memory of the context?
hippocampus
how do you test fear conditioning?
- pair a sound with an electric shock
- rat will learn to feat the sound
- an associative memory
- rodents with lesions in amygdala lack a conditioned fear response
who is patient SM?
- damaged amygdala but intact hippocampus
- tested ability to rate intensity of human facial expressions
- failed to recognize fear
- damage was caused by Urbach-Weithe condition
what motivation and reward be driven by?
- drive states directed towards maintaining physolical homeostasis (eg apeptite)
- motivational states driven by rewarding/pleasurable and reinforcing stimulus (eg dont want bland food)
what is the reward pathway?
- stimuli signal the presence of reward by activating dopaminergic neurons in the VTA that project to the NuccAcc
- this is the reward pathway
what is the VTA?
ventral tegmental area
what is the NucAcc?
nucleus accumbens
what acts on the reward pathway?
all addictive substances or behaviors activate this pathway
