Systems level architecture Flashcards
Evolution: pain. How does the body react?
Spinal cord-withdrawal reflex. Requires sensory receptors.
Evolution: loom. How does the body react?
Need an avoidance mechanism. Need sensory mechanism to see threat/hear. Sensorimotor midbrain tackles this.
Evolution: learned threat. How does the body react?
Avoidance mechanism. Uses cortex and limbic system. Need a high level of processing (Memory)
Response suppression. What is it?
High level of response and cognitive control
Spinal cord?
Part of the CNS within the vertebral column
What is the vertebral column comprised of?
The cervical/thoracic/lumbar and sacral region
Spinal cord roots
Have the dorsal and ventral roots
Dorsal root?
Afferent. Is sensory receptors. Affected by the world
Ventral root
Efference. Has an effect on the world (is an output). Motor.
Ventral root
Efferent. Has an effect on the world (is an output). Motor.
Subdivisions of the brain
Forebrain(telencephalon and diencephalon)/Midbrain (mesencephalon)/Hindbrain (metencephalon and myelencephalon)
Hindbrain: medulla
- Base of brain: medulla
- Basic controls such as respiration. Low level control
- Excretory reflexes
- Motor control: balance
- Can be damaged by intracranial pressure
Hindbrain: pons
- Relay from cortex and midbrain to cerebellum
- Contains millions of neuronal fibres
- Pontine reticular formation (generates patterns such as walking)
Hindbrain: cerebellum
- Motor structure
- Smaller than brain but contains many neurons as the rest of the CNS
- For ‘motor errors’ adjusts weights to eliminate error
- Thought exclusive for motor coordination but recently implicated in cognitive and affective/emotional function
Midbrain: tectum (called colliculi)
- Visual/spatial and auditory frequency range
- Has two parts: superior colliculus and inferior colliculus
- Superior: sensitive to sensory change: defensive movements. Not quite conscious. Can detect an object that is getting bigger
- Inferior: similar but for auditory signals.
Midbrain: tegmentum
Has three structures
1.) The periaqueductal gray: for pain modulation and receiving pain signals. Has a role in pain (ascending and descending pain signals). Has roles in reproduction and defensive behaviour
2.) Red nucleus: target of cortex and cerebellum projects to spinal cord. Has a role in pre-cortical motor control (esp arms and legs)
3.) Substanitia nigra: part of the basal ganglia. Substantia nigra pars compacta: basal ganglia input
Substantia nigra pars reticulata: basal ganglia output
Forebrain: what are the two main parts
The Diencephalon. Has two main parts:
- ) Thalamus
- ) Hypothalmus
Forebrain: thalamus (relay structure)
- Has specific nuclei: relay signals to cortex/limbic system for all sensations
- Non specific nuclei: role in regulating state of sleep/wakefulness/levels of arousal
- Important relays from basal ganglia + cerebellum back to cortex
Diencephalon: Hypothalamus
- Regulates the pituitary gland which regulates hormonal secretion: interface between brains + hormones
- Role in hormonal control of motivated behaviours: hunger/thirst/pain/temperature/pleasure/sex
Forebrain: cerebral cortex
Subcortical (under cortex) portions: basal ganglia and limbic system
Basal ganglia
- Parkinsons is a disease of the B.G
- Is a group of structures
- Loop organisation
- Involved in motor function
- Role in action selection and reinforcement learning
Limbic system
- Group of structures
-involved in emotion and memory
Influences the formation of memory by integrating emotional states with stored memories of physical sensations - Amygdala: important. E.g. have a bad experience with a carrot so you have a bad emotional reaction to a memory of a carrot
What are the 6 structures of the limbic system?
- ) Amygdala
- ) Hippocampus
- ) Fornix
- ) Cingulate gyrus
- ) Septum
- ) Mammilary body
Cerebral cortex: cortical lobes
1.)
Cortical lobes
- Gray matter (6 layers): made of cell bodies
- White batter: made of fibres/axons
Frontal lobe
- For planning/response inhibition
Parietal lobe
- Has the postcentral gyrus
Contains the primary somatosensory cortex - Permits complex spatio-temporal predictions e.g. catching something when you’re moving
Temporal lobe
- Contains primary auditory cortex
- Inferotemporal cortex: recognition of faces and objects
Occipital lobe
- Has a dorsal stream and a ventral stream
Dorsal: vision for movement. Where is it in relation to us?
Ventral: vision for identification. What does it mean to us?
Cerebral cortex: cortical lobes
- ) Frontal lobe
- ) Parietal lobe
- ) Temporal lobe
- ) Occipital lobe
