Summary Brain and behaviour revision notes (ps2061)
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Course
Brain and behaviour (PS2061)
Institution
Royal Holloway University Of London
An extensive summary of the module that focuses on the most important aspects of the lectures of the module 'brain and behaviour' has diagrams and a new format to make it easier to memorise. Also my own phrasing and added comments for extra learning.
Functional Networks: What Are ‘Brain Systems’?
CORTICAL NETWORKS
Are networks in the cerebral cortex that process and exchange information.
There is a common hierarchical plan for the organisation of some networks. Larger parts of these networks focus on
modality, processing information related to one type of input/output (such as auditory, visual, etc).
Sensory inputs and motor outputs are represented at different levels of abstractions (different ways) at different levels
of these networks. Information gets transferred and transformed along its specific network and representations (this
object is rectangular and has a rough texture..) depict the stimulus and sends that information to another part of the
brain that will attach a value to the stimulus (this is money and is a reward). A stimulus is represented differently in
different points in the brain depending on that brain part’s function.
Levels of abstraction: there are low levels of abstraction in lower parts of the network but very abstract at much higher
levels.
THE CORTEX
Before information reaches the cortex: Thalamus. The gateway to the cortex.
The thalamus is outside and below the cortex, deep inside the brain. It is a subcortical, heterogeneous structure
composed of a collection of nuclei and the cortex is reciprocally connected to the thalamus. There are parts of the
thalamus that are specialised at communicating with different parts of the cortex. It is very modular and
communicates very specifically with different parts of the cortex.
Information gets sent from the thalamus to the cortex and information comes back to the thalamus from the cortex.
-- CORTEX STRUCTURE --
The cortex is structured in three general functional types: primary cortex (where info comes in from thalamus),
unimodal cortex (receives info from pc) and supramodal cortex (receives info from uc).
, Primary cortex is the first level of cortical processing. The information content that it responds to is very low level.
All of the activity in primary cortex is related to one modality. The primary cortex is organised topographically. This
means that neurons adjacent to each other change in relation to the parameter space.
Unimodal cortex is a higher level, and represents information in a more abstract way. It is an intermediate level of
processing where activity is nevertheless specific to one modality. Topography begins to break down. It doesn’t
represent the physical parameters of the world as obviously as the primary cortex.
Supramodal cortex is where information is represented at the highest level of cortical processing at a very abstract
level. Apex of the hierarchy where info is represented in at the same level as the way you consciously think (abstract
concepts: eg. What is this worth to me, is this interesting?). Places like the prefrontal cortex, posterior parts of the
frontal cortex are supramodal in nature. The neural organisation in these areas do not care of physical parameters of
the real world (eg. Doesn’t care about the retinotopic nature of stimuli). Deep meaning to stimuli.
PRIMARY CORTEX
Primary visual cortex: In the PVC, the lateral geniculate nucleus (LGN) is the thalamus for the visual cortex. Visual
information from the retina ends up in the LGN, which then distributes that info to the PVC at the very back of the
brain. The PVC is the first cortical area to process visual info.
The PVC represents the parameter space in the real world. Info in PVC is organised retinotopically. The real world is
physically represented in the way that the brain is organised. The cells in the PVC are laid out physically and
different areas of the visual field are represented in discrete areas of the cortex.
Other modalities also have primary cortices.
Primary auditory cortex: An area in the thalamus called medial geniculate nucleus (MGN). All auditory info that
reaches the cortex comes through the MGN. The MGN projects to the primary auditory cortex in the superior
temporal gyrus. It is also referred as the core. Cells are responsive to the frequencies of tones. Some neurons in the
, PAC become responsive to higher frequencies, and others, to lower frequencies. There is tonotopic organisation. The
organisation of the cells represent the parameter space of the physical world (frequency of sounds coming).
Primary motor cortex: Information is sent out to the spinal cord. Motor commands are generated and leaves the
brain for the command to be followed through. This is the lowest point in the motor hierarchy, which still defines it as
a primary cortical area. PMC neurons are topographically organised. Voluntary movement is associated with the
activity of a large population of cells in the PMC. Population activity is related to the direction of the movement.
UNIMODAL CORTEX
Unimodal visual cortex: has a plethora of visual areas outside the PVC. These are areas of specialisation, where they
are selectively responsive to specific visual properties. Processing is distributed and specialised, in particular
directions and areas. The area specialised for selective visual motion is MT (V5). It is a higher level of abstraction
because it is interested in particular things such as direction of movement. Information at each level of the stream
becomes more abstract. The PVC can send info via the dorsal stream into the posterior parietal cortex, which is
interested in location and processes location-related info. The ventral stream processes object-related information and
extends into the temporal lobe. Unimodal visual areas are distributed in the occipital, temporal and parietal lobes.
Unimodal auditory cortex: Has a similar organisation to the visual system. The MGN sends information to the core,
which sends its outputs to the belt cortex, which is received in the parabelt cortex. The belt cortex completely
surrounds the core. Beyond that is the parabelt cortex which completely surrounds the belt. The parabelt sends its
outputs to other temporal lobe areas, such as vernickle’s area.
Unimodal motor cortex: also known as premotor cortex, it has its own bunch of areas in the frontal lobe and
information is send out to the PMC and spinal cord. It then reaches the muscles. There are many subdivisions, but it
has been broadly divided into three subregions: dorsal, ventral and medial. In front of the primary motor cortex is the
premotor cortex. Speech production is in the motor domain. Premotor areas generate activity that kicks off before a
movement is made. Premotor neurons encode preparatory activity before a movement is made.
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