Systems Level CNS Artchitecture Flashcards
Central nervous system
Brain
Spinal cord
Peripheral nervous system
Division located outside the skull and spine
Somatic nervous system
Interacts with the external environment
Autonomic nervous system
Regulates the body’s internal environment
The spinal cord of CNS
Dorsal root sends signals to CNS (afferent)
This is sensory
At back
Ventral root receives signals from the CNS (efferent)
This is motor
At front
Brain compromises hierarchy of functional systems providing increasingly sophisticated actions
The subdivisions map onto the hierarchy
Hindbrain- medulla
Contains tracts carrying signals between the rest of the brain and the body
Contain caudal part of the reticular formation (‘little net)
-low level sensorimotor control such as balance
Involved in a variety of vital functions
Sleep waking up
Motor plant- movement, maintenance of muscle tone Various cardiac, circulatory, respiratory, excretory reflexes
Hindbrain- Pons (bridge)
Relay from cortex and midbrain to the cerebellum
Contains millions of neuronal fibres
Pontine reticular formation (pattern generators) e.g. for walking don’t have to think where to/how to place feet
Hindbrain- Cerebellum
Smaller than the brain but contains as many neurons as all the rest of the CNS
“Motor errors” between intended movement and actual movement – cerebellum adjusts synaptic weights to eliminate error
Online correction can take place during the movement : motor learning.
Thought exclusive for motor coordin-ation – recently implicated in cognitive and affective/emotional function
Decides how you do something
Midbrain
Contains the tegmentum and tectum
Tectum- visual/spatial and auditory frequency maps
The superior Colliculus o the tectum is sensitive to sensory change- orienting/ defensive movements
The inferior colliculus of the tectum is similar but for auditory events
Midbrain- tegmentum
Made up of
Periaqueductal gray
Red nucleus
Substantia nigra
The Periaqueductal gray
Role in defensive behaviour
Role in pain ascending and descending signals
Role in reproduction
Red nucleus
Target of the cortex and cerebellum, projects to spinal cord
Role in pre- cortical motor control (especially arms and legs)
Substantia nigra – part of basal ganglia
Substantia nigra pars compacta
(Dopamine cells) – basal ganglia Input
Parkinson’s disease
Substantia nigra pars reticulata –
basal ganglia output
Diencephalon- forebrain
Made up of thalamus and hypothalamus
Thalamus- relay structure
Specific nuclei: relay to cortex/limbic system for all sensations (but smell…)
Non-specific nuclei : Role in regulating state of sleep and wakefulness and levels of arousal
Important relays from basal ganglia and cerebellum back to cortex
Hypothalamus
Regulates the pituitary gland which regulates hormonal secretion: interface between brain and hormones
Role in hormonal control of motivated behavior
including hunger, thirst, temperature, pain, pleasure and sex
Forebrain- cerebral cortex
Subcortical (under the cortex) made up of:
Basal Ganglia Limbic system
Basal ganglia
Group of structures
Loop organisation
These structures throughout to be involved in motor function since involvement in movement disorders
Limbic system
Group of structures
These structures involved in emotion, motivation and emotional association with memory
The limbic system influences the formation of memory by integrating emotional states with stored memories of physical sensations
What is the limibic system made up of
Amygdala
Hippocampus
Fornix
Cingulate gyrus
Septum
Mammillary body
Amygdala
Involved in associating sensory
stimuli with emotional impact
Hippocampus
Involved in laying down memory (long term)
Involved in spatial memory
Cingulate gyrus
(Limbic cortex)
Linking behavioural outcomes to motivation and autonomic control – atrophied in schizophrenia (wasted away)
Mammillary body
Breast shaped Important for the formation of recollective memory – amnesia
Septum
Involved in defense and aggression
Fornix
C-shaped bundle of fibers
Carries signals from the hippocam-pus to the mammillary bodies and septal nucleus
Forebrain- cerebral cortex
Gray matter- 6 layers- cell bodies
White matter: fibres/axons
Biggest part of the brain in primates
Cerebral cortex- frontal lobe
Contain the precentral gyrus from which motor instructions (particularly for fine motor control) that are sent to muscles controlling hands and feet.
Primary motor cortex: contains many of the cells giving origin to the descending motor pathways - it is involved in the initiation of voluntary movements.
Premotor and supplementary motor areas: higher level motor plans and initiation of voluntary movements
Involved in judgmental roles and emotional modulation
Working memory: short term information rather than long term factual
Control of behaviour that depends upon context or setting
Prefrontal cortex generating sophisticated behavioural options that are mindful consequences
Cerebral cortex- parietal lobe
Contains the postcentral gyrus which receives sensation from the rest of the body
(Primary somatosensory cortex)
This maintains representations of the body’s and of the head’s position in space
Permits complicated spatio-temporal predictions – e.g. catching something when you are moving
Cerbral cortex- temporal lobe
Contains the primary auditory cortex
Inferotenporal cortex reignites faces and objects
Plays important roles in integrating sensory information from various parts of the body
Interface between cortex and limbic system – association of affect/emotion with things
Cerebral cortex- occipital lobe
Dorsal stream
Vision for movement
Where [is it in relation to us – path towards motor areas]
Ventral stream
Vision for identification
Path towards temporal/limbic areas
