forebrain(telencephalon) Flashcards
what is the telencephalon composed of?
-Basal ganglia
-Limbic system
-Neocortex
(the limbic system is not a lobe but is highly connected to the cortex)
what’s the function of the basal ganglia?
Receives input from (dopaminergic) substantia nigra and tegmentum
Reciprocal connections with the cortex through different frontal-striatal loops
-Connects sensory and motor regions
-Regulates movement
-associative learning
-Control of movement, not production
-Adjust movement to the environment (goal-directed behaviours, flexibility, requires associative learning)
what happens if the basal ganglia remains intact, but gets disconnected from the brain?
When the basal ganglia are disconnected from the cortex, the signals that help adjust and refine behaviours can’t get through properly. This makes it hard to change behaviours based on new information or to plan complex actions.
what you can still do:
-Eat, drink, sleep, and navigate simple paths normally.
-Learn basic behaviours through conditioning.
what is affected:
-Have trouble adapting behaviours to changes in the environment.
-Struggle to stop behaviours that are no longer rewarded.
-Find it difficult to plan and carry out complex actions.
what is self-maintenance (basal ganglia)?
it links voluntary and automatic movements well enough for self-maintenance in a simple environment
what is control and intention? (cortex)
it performs a sequence of voluntary movements in organized patterns. responds to patterns of sensory stimulation. contains circuits for forming cognitive maps and for responding to relationships between objects, events and things.
-adds emotional value
What symptoms do you expect when the basal ganglia is affected?
-Excessive movement
Huntington’s disease - chorea
Tourettes syndrome – involuntary tics, vocalizations
-Loss of movement
Parkinson’s Disease
Reduced dopaminergic input from substantia nigra
Tremors
Rigidity
Cognitive Inflexibility
-Learning deficits, stimulus-response associations
Gambling, drug addiction, impulsivity
what are the main structures of the limbic system?
-Amygdala
-Hippocampus
-Cingulate cortex (Hypothalamus –>hippocampus)
-Fornix (hipp –>hypothalamus)
what are the main functions of the limbic system?
-memory, learning & spatial behaviour (hippocampus)
-Emotional control of behaviour
-stimulus-outcome associations
-Control of “conscious” behaviour by episodic and emotional memory
what are reciprocal connections? which reciprocal connection does the limbic system have?
they are two-way communication pathways. This means that information can travel in both directions between two regions.
-Olfactory bulbs,
-Hypothalamus/mamillary bodies
-Cortex
what is the function of the neocortex?
-Extend the usefulness of all behaviours or make them adaptive in new situations
-(control and intention)
-Move around in the world and adapt to new situations
-Integration of sensory information, memory and motor plans
-Interpret sensory information/bodily state
-Make plans to respond to, or change sensory information
-reduce feelings of hunger, loneliness
-Execute plans
-Combine movement sequences
-Generate complex goal-directed behaviours
-Check new state
how is the neocortex organized?(hierarchy)
1)Sensory areas: posterior of the central sulcus \understand the world
-Primary visual, auditory & sensory cortex
Receives first sensory input
Basic processing
-secondary areas
Adjacent to primary areas
Interpretation, more detailed processing (colour, movement, form)
-Tertiary/association areas
Complex processing such as language, music, memory, attention etc
2)Motor areas (anterior of central sulcus), move around and manipulate the world:
-Primary motor area
projects to the spinal motor system
-Secondary areas
Adjacent to primary areas
Motor planning, integration with sensory information
-tertiary/association areas
More complex planning, attention, and integration with sensory information
Complex cognition: directing attention, adjust responding to changing environments
what are the differences between the motor and sensory cortical layers?
they both have 6 layers.
Layer I-3
Receive input from other cortical areas
Well developed in secondary and tertiary areas
Layer 4
Received input form sensory systems
Granular cortex
Well developed in primary sensory areas
Layer 5 and 6
Pyramidal neurons
Send projections to thalamus and the spinal cord
Well developed in motor areas
-sensory cortex: 4th layer is well-developed
-motor cortex: 5th layer well developed
what are Cytoarchitectonic maps (of the neocortex)?
A detailed map of the neocortex based on the microscopic structure of its cells. It divides the cortex into regions with different cellular architectures, which often correspond to different functional areas. This type of mapping is fundamental for understanding how different parts of the brain work and how they are organized.
-Based on density differences of cells
-Brodman’s areas (areas are essentially specific regions identified through the principles of cytoarchitectonic mapping,)
-Correspond closely to maps defined by the function of areas
What is the Luria model?
- a hierarchal organization of the cortex
-serial processing
-explores how brain lesions affect different levels of information processing and behaviour. (soccer example of how lesions in certain areas can affect a game)
1)sensory:
a)Primary visual zone: blind spot, unable to see the ball
b)Secondary visual zone: Players and the ball are seen, but it is not recognized as a soccer game
c)Tertiary zone: Lacking experience of value/significance of winning the game
2)motor:
a)Primary: difficulty in specific movements, kicking the ball
b)Secondary: problems executing sequences of movement needed to play soccer
c)Tertiary: No intention to be a soccer player
what is the Felleman and van Essen model?
- a hierarchal organization of the cortex
-Re-entry: Each cortical area is reciprocally connected with many other areas
-Interactions between regions within one hierarchical level
-Ascending (forward) and descending (backward) projections
