The Modular Brain Flashcards
What are the divisions of the Nervous System?
Central Nervous System (CNS)
- composed of 2 divisions: brain + spinal cord
-> walking is controlled by spinal cord by central pattern generator
Peripheral Nervous System (PNS)
- composed of 2 divisions: Somatic NS + autonomic NS
What is the Somatic Nervous System (SNS)?
- How we interact with the external world
-> motor action, sensing + feeling things around you
Afferent nerves -> send sensory info towards the brain
Efferent nerves -> send motor info away from the brain
What is the Autonomic Nervous System (ANS)?
- Modulates visceral functions + sensations in the body, involuntary
Sympathetic NS -> “fight or flight”
- Pupil dilation, increased heart rate, inhibits digestion
Parasympathetic NS -> “rest + digest”
- Pupil contraction, decreased heart rate, stimulates digestion
What are the main divisions of the brainstem?
Brainstem is a subcortical structure
Midbrain-> top of brainstem, consists of smaller brain areas
-> involved in motor movement of eye and in processing of vision + hearing
Pons -> middle of brainstem - densely connected to cerebellum (motor movements) + contains relays from cerebellum to other parts of brain
-> also responsible for relays regarding sensory + motor info
Medulla -> bottom of brainstem
-> contains neural connections that are early on in sensory info + motor info, sent straight to the spinal cord
What are the components of the midbrain?
Has 2 division: Tectum + Tegmentum
Tectum -> dorsal surface of midbrain
-> composed of superior + inferior colliculi
superior colliculus - visual-motor function
inferior colliculus - auditory function
Tegmentum -> division of midbrain ventral to tectum
-> contains reticular formation, tracts of passage, periaqueductal gray, red nucleus, substantia nigra, cerebral aqueduct
Red nucleus -> motor function
Substantia nigra -> dopamine related, so related to reward systems or motor planning
Cerebral aqueduct -> carries cerebral spinal fluid to spinal cord
Reticular formation -> mostly for wakefulness, relevant for sleep + awake states
Periaqueductal gray -> relays info about pain
What are the other 2 subcortical structures above the brainstem?
Basal ganglia -> receives info from dopamine areas in midbrain as important for motor planning + reward
Made up of:
- Striatum (caudate + putamen)
- Globus pallidus
- Nucleus accumbens
Limbic system -> generally relevant for memory (storing memories) + processing emotions
Composed of:
Amygdala -> relevant for fear related processing
Mammillary bodies
Hippocampus
Septum
Fornix
Cingulate cortex
Where is cerebral spinal fluid produced + what are its functions?
Cerebral spinal fluid (CSF) fills the subarachnoid space, central canal + cerebral ventricles
Central canal -> small, central channel that runs the length of the spinal cord
Cerebral ventricles -> 4 large internal chambers of brain: two lateral ventricles, the third ventricle and the fourth ventricle
-> these are all carrying + creating CSF
Functions:
- Contains nutrients to send to different areas of brain
- Waste removal
- Physical protection of brain as CSF acts as a cushion
-> when there is an impact to the head, it absorbs some of that impact
What is the cortex?
Divided into 4 main areas:
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal
Ridges in brain -> gyrus
Grooves in brain -> sulcus
Lateral sulcus (lateral fissure) -> separates frontal, parietal + temporal lobe
Central sulcus (central fissure) -> separates frontal lobe + parietal lobe
What are the cardinal directions for referring to where different brain areas are?
Medial = towards the centre of the body
Lateral = away from the centre of the body
Anterior = forward (toward the nose end)
Posterior = back (toward the tail end)
Dorsal = up (toward the surface of the back or top of head)
Ventral = down (toward the surface of the chest or bottom of head)
Superior = top of primate head
Inferior = bottom of primate head
examples:
Superior temporal gyrus -> Auditory processing
Posterior occipital area -> Visual
Postcentral parietal gyrus -> Somatosensory (everything relating to touch sensation on different parts of body)
Precentral frontal gyrus -> Motor processing
Posterior parietal cortex -> “where” pathway (relevant for attention + perceiving motion)
Inferior temporal gyrus -> “what” pathway (object processing + vision)
If you look at the brain from the bottom (inferior temporal gyrus), you get the fusiform gyrus = selective for faces
-> if you get a lesion in this area, this is known as a condition called prosopagnosia -> deficit of recognising faces + have trouble fusing different parts of face into a recognisable whole
What are cortical maps within sensory areas?
Motor + somatosensory - specifically organised
Auditory:
-> cochlea turns sound info into something our brain can understand, an electrical signal
-> it does this by splitting the sound vibrations into different frequencies
- Closest to opening = responsible for high frequencies
- Further down = low frequencies
-> being able to hear these differences in pitches is important for our ability to understand speech + other types of important sound
Describe lateralisation of function
- Two halves of brain are separated by longitudinal fissure
- Both halves of brain are largely symmetrical
- Theres a large set of neural connections between the two hemispheres - known as corpus callosum
Somatosensory (touch + pain sensation):
- The left side of brain is sensing the right side of body
General rule: Cortex activates + responds to the contralateral (opposite) side of body
Motor:
-> this rule is also true for motor system
- If we think of right hemisphere, its sending motor neurons down to activate the opposite side of the body
-> limbs on left side as activated by RH of brain
Visual:
-> process separate hemispheres of visual fields
- Left visual field = everything we see on left side
- Right visual field = everything we see on right side
Right cortex is responsible for left visual field
Left cortex picks up right visual field
-> because info from both eyes is combined because of the crossing at the optic chiasm
