brain anatomy & localisation of function Flashcards
which 2 categories is the brain separated into?
brain stem (posterior part continuous with spinal cord) - contrl over physiological and metabolic processes cerebral hemispheres
what is the corpus callosum and what is its function?
white matter tracts
connecting the 2 hemispheres allowing them to communicate
what is the cerebral cortex?
grey matter on the outer part of the brain and is made of bodies of neurons
what is the difference between white and grey matter?
white matter (due to whiteness of myelin) - situated under grey matter and is made of long elongates part of neurons called axons
grey matter - outer part of the brain made up of the soma and dendrites of neurons (start and middle)
what is the difference between a gyrus and a sulcus?
gyrus - outside of fold
sulcus - inside of fold and major ones referred to as fissures
what is the function of the myelin sheath on axons?
made up of proteins and fatty substances and enables electrical impulses to travel quickly along the nerve cell
what is intercallosal transfer?
refers to electrical impulses which travel from neurons in one hemisphere to the other via the corpus callosum
what are the 3 major sulci/fissures and what do they separate?
- central sulcus / fissure of Rolando - separates the frontal lobe and the parietal lobe & primary motor (frontal) and somatosensory (parietal) cortex
- parieto-occipital sulcus
- sylvian / lateral fissure - separates frontal and parietl lobe above from temporal lobe below
they separate the 4 lobes
what are the coordinates and orientations for different parts of the brain?
coordinates:
(from side on with the front of brain on the left going clockwise) superior/dorsal to posterior/caudal to inferior/ventral to anterior/rostral
what do medial superior and inferior refer to?
what does lateral refer to?
medial superior = near top middle
medial inferior = near bottom middle
lateral = either on the right or left hand side
what are the 3 different brain slice orientations?
axial - view would be as if looking down on brain
coronal - view would be one half of brain from the front or back e.g cutting through middle
sagittal - view would be as if looking sideways at brain
what does cytoarchitecture refer to?
a finding by Brodmann
that cortical regions vary in detailed cellular structure (types of neurons) and arrangement (number of layers, density)
and divided cortex into areas up to 52 in this way
what are 3 specific groups of neurons and what do they do?
reticular formation - control of arousal and sleep (with Reticular Activating System determining level of alterness)
SCN - controls circadian rhythms
ventromedial nucleus - controls conversion of blood glucose into body fat
what is phrenology?
school of thought that attempted to localise mental processesanatomically
Gall
what is equipotentiality?
cognitive functions aren’t localised
but basic physiological regulation and motor functions are localised
Flourens
what is the hierarchy of perception?
primary areas - where sensory info arrives e.g thalamus (occupy small area of cortex compared to other 2 parts)
secondary areas - perceptual info gets passed to them for more sophisticated processing
association areas - info from different modalities and of different types is intergrated
which 2 pathways is visual processing separated into?
‘what’ including V1,2,4 and inferotemporal cortex
‘where’ including V1,2,3,5 and parietal cortex
what is the specific function of the Fusiform gyrus?
specialises in facial recognition
so damage/ cell loss results in impaired face recognition (prosopagnosia)
what is the hierarcy of motor control?
and which of Brodmann’s areas are responsible for motor control?
primary motor cortex - direct control over moevment (occupy small area of cortex compared to other 2 parts)
premotor and supplementary motor - planning of movement and intergration of motor beh. with other beh.
Brodmann areas of 4,6,8 are motor areas
why does paralysis often occur after a stroke?
main artery runs past the primary motor cortex which is responsible for direct control over movement so if impaired =paralysis
which region expanded more than any other in course of evolution in primates?
dorso-lateral prefrontal cortex but patients with lessions rarely show deficits
what is an example of challenges in functional localisation?
Broca’s area is activated during 10% of studies not speech production related
could be that area isn’t specialised to specific function
or only a small area of Broca’s area is specialised in speech production
what did Duncan mean by ‘multiple demand’ brain areas?
certain brain areas which were always activated over different cognitive tasks
what is meant by reverse inference in relation to localisation of function?
using activation in certain brain areas and the knowledge of which functions these brain areas serve to infer what is going on
e.g seeing which parts of brain are active in PTSD flashbacks to determine whether auditory, visual etc.
