2.9 Cortical Networks Flashcards
(18 cards)
Describe the cerebrum
The cerebrum is the largest part of the brain (taking up 80% of the brain) and is responsible for higher mental functions. It is formed of a right and left hemisphere that is connected by the corpus callosum. The 4 lobes of the cerebum are the frontal lobe, occipital lobe, temporal lobe and parietal lobe.
Describe the specificity of the cortex
The cortex has a high degree of specificity, you can map both sensory and motor areas in the cortex to their corresponding specific areas in the body that they control.
How does the complexity of a movement correspond to the brain area
The more complex the movement, the greater the brain area in the motor cortex given towards it.
How does the degree of sensing in the region correspond to the brain area
The more sensing going on in the region, the greater the brain area in the sensory cortex given towards it.
What are the 4 lobes of the cerebrum
The frontal, occipital, temporal and parietal lobes
What on the brain increases the brain surface area
sulci and gyri
What is significant about frontal lobe development in humans
The maturation of the frontal lobe is late, in adolescence there is synaptic primming to lose unessecary synapses. The dorsolateral prefrontal cortex (involved in control of impulses, judgement and decision making) is one of the latest areas to reach adult levels of cortical thickness
Describe the two areas of the cortical motor area
The pre motor cortex and the primary motor cortex. Stimulation in primary motor causes simple movement, but in premotor causes complex movement.
Describe the effects of disturbance in the primary motor cortex and the pre motor cortex
Disturbance to primary motor causes weakness in corresponding affected body parts, but disturbance to premotor causes more complex motor deficits
Describe the primary motor cortex
It sends signals via the corticospinal tract that control the limb, hand, finger, trunk and facial movements. It receives input from the prefrontal cortex and cingulate cortex.
What are some areas outside of the motor cortex also concenrned with motor movements
Subcortical areas such as the basal ganglia and cerebellum
Describe the pre motor cortex
The premotor cortex is involved in movement planning/sequencing. It has 2 distinct regions, the supplementary motor area and the lateral pre motor area. The supplementary motor area is more involved in internally generated movement whereas the lateral pre motor area is involved in externally guided movement. The pre motor cortex has many projections to the primary motor cortex and is also directly connected to motor neurons.
What is the most interconnected cortical region
The prefrontal cortex as it plans complex movements so takes in lots of inputs.
Describe the pre frontal cortex
The prefrontal cortex controls goal-directed behavior, decision-making, and personality, adapting actions to internal and external cues.
Give the different effects of schizophrenia on the brain systems
- positive symptoms (things added)- Delusions, hallucinations, thought disorder
- negative symptoms (things taken away)- Decreased motivation, diminished emotional expression
- cognitive defecits
- Sensory, sensorimotor and motor abnormalities
Schizophrenia has a big impact on the prefrontal cortex
Describe the dopaminergic pathways that are involved in schizophrenic symptoms
The mesocortical pathway innervates the dorsolateral PFC and ventromedial PFC. The mesolimbic pathway innervates the striatum from the ventrotegmentum. Mesolimbic overactivity causes the positive symptoms of schizophrenia and mesocortical underactivity causes the negative, cognitive and affective symptoms of schizophrenia
How do d2 dopamine receptor antagonists impact different schizophrenic symptoms.
As they reduce dopaminergic transmission and therefore cause underactivity in the pathways, it is useful for treating the positive symptoms but worsens the negative symptoms
Describe the 2 ways in which schizophrenia impacts glutamatergic transmission
There is a glutamatergic pathway from the prefrontal cortex that synapses onto a GABA interneuron which then inhibits the mesolimbic dopamatergic transmission. This glutamatergic pathway is normally constituatively active. However with schizophrenia, the glutamatergic neurons are suppressed so the mesolimbic dopamatergic transmission can’t be supressed, hence causing positive symptoms.
The glutamatergic pathway also innervates the mesocortical pathway, but without an inhibitory interneuron, hence supression of the glutamatergic pathway also causes supression of mesocortical, hence negative symptoms.
