Neuroanatomical models of affective disorders Flashcards
What is the Brodmann Area (BA) 10 known as?
- Frontal Polar Cortex
- Anterior Rostral Medial PFC
- one of the most recently evolved areas
How does Frith (2007) consider the Brodmann Area (BA) 10?
> “key region in mentalising”
> In healthy people, BA 10 activated during fMRI in 3 tasks:
- Mentalising
- Person perception
- Self-perception
What do mentalising tasks refer to?
Understanding the behaviour of characters in terms of mental states
- stories, cartoons
What do tasks on people perception refer to?
Questions about long-term dispositions
What do self-perception tasks refer to?
Questions about one’s own long-term dispositions
Which brain areas were discovered as related to inappropriate behaviour when damaged?
> Right anterior temporal
- affected in Frontotemporal Dementia
> Ventral meidal PFC
- with damage / loss of tissue
What is Frontotemporal Dementia?
Group of neurodegenerative disorders
- leading to loss of tissue
- resulting in inappropriate social behaviour
What is observed in patients with amygdala damage?
- Less risk averse
- Abnormalities on gambling tasks: take riskier gamble
What is the role of the amygdala in social and emotional behaviour?
Detecting both positive AND negative emotionally salient stimuli
How did Walle Nauta extend the definition of the structures involved in the limbic system (1960?
Included the “Limbic Forebrain Structures”
What are the limbic forebrain structures (Walle Nauta, 1960)?
- Orbitofrontal cortex
- Hippocampus
- Amygdala
- Hypothalamus
- Septal region
What is the location and role of the orbitofrontal cortex?
- Part of ventral medial PFC
- Extends laterally
- Sits just above eyeballs
- Damage impacts social behaviour
What is the location and role of the hypothalamus?
- Subcortical
- Projects to hormonal system
What is the location and role of the septal region?
- In the septum
- Contains very small nuclei
- thought relevant to emotions
Which damaged brain areas do not lead to abnormal social behaviour?
Parietal and occipital cortex
How does posterior cortical atrophy (form of Alzheimer’s) show that damaged parietal and occipital regions do not lead to abnormal social behaviour?
> Memory is retained
-> doesn’t start in hippocampus
> Visual problems BUT behaviour remain intact
- > starts in back of the brain
- damaging parietal and occipital cortex
What are prefrontal-striato-thalamic loops?
> Dorsolateral frontal cortex connected with part of striatum
- to Caudate nucleus AND Putamen (by small bridges)
> Caudate nucleus and Putamen are connected to Thalamus
=> closed loop of reciprocal systems
What are the parallel frontal subcortical systems?
Prefronto-striato-thamalic loops that start from frontal cortex, connecting to subcortical structures
- motor
- oculomotor
- dorsolateral prefrontal
- lateral orbitofrontal
- anterior cingulate
Cortex -> Striatum -> Globus pallidum, Substantia nigra -> Thamalus
What are the most relevant prefrontal-striato-thamalic loops to the limbic system?
> Lateral orbitofrontal loop
> Anterior cingulate loop
- evolutionarily older
- always considered part of limbic system
What is the aetiology of Parkinson’s disease?
Degeneration of dopaminergic neurons in substantial nigra (DA projections to motor cortex)
How are the frontal subcortical loops involved in Parkinson’s disease?
> Degeneration of DA neurons in substantial nigra
> Ventral tegmental connected to midbrain (striatum, nucleus accumbens) and PFC
-> mesocorticolimbic pathways
> Patients with Parkinson’s disease suffer from
- anxiety
- depression
Why are many models of affective disorder based on the idea of frontal subcortical loop systems?
Because the dopaminergic, monoaminergic, and glutamatergic NTs modulate the frontal subcortical loop systems
What does the top-down frontal cognitive control model of social and emotional functions suggest?
Frontal cortex controls information in other cortical and subcortical areas
- “when an automatic response needs to be overcome”
- for non-standard situations
What does the bottom-up subcortical control model of social and emotional functions suggest?
Ventral (medial) frontal cortex stores linkages of
- subcortical “somatic markers” in hypothalamus
- action knowledge in posterior areas
e. g. risky gambling game:
- hypothalamus may signal via increase in arousal, detected by ventral (medial) frontal cortex
-> helps making smart decision, avoid risky situations
Who constructed the bottom-up subcortical control model of social and emotional functions, and how?
Damasio group
- patients with ventral medial frontal cortex damage had problems in rapid and complex decision making
- they knew decisions were bad but couldn’t stop themselves
What does the reciprocal fronto-temporo-subcortical integration model of social and emotional functions suggest?
Frontal cortex stores specific information:
- context-dependent knowledge of sequences of social actions/events
- > cortex necessary to enable context-appropriate social behaviour
- explains inappropriate behaviour of people with damage to frontal cortex
How did Miller and Cohen (2001) conceptualise the top-down frontal cognitive control model of social and emotional functions?
“the role of the PFC is modulatory rather than transmissive”
- “PFC guides activity flow along task-relevant pathways in more posterior and/or subcortical areas”
- task-relevant pathways of PFC activity = “map that specifies which pattern of “tracks” is needed to solve the task”