Brain Systems and Circuits Flashcards
Frontal lobe functions
Motor Cortex
- contralateral somatotopic organisation
Premotor cortex
- preparing and executing limb movements
- learning
- social cogintions
Prefrontal cortex
- attention
- working and prospective and temporal memory
- planning
- decision making
- self control
- language (broca’s area)
Temporal lobe function
Auditory functions: superior temporal gyrus
- primary auditory cortex
- language recognition: Wernicke’s area (comprehension deficits)
Memory and Emotion functions
- medial temporal lobe involved in encoding long term declarative memory (hippocampus)
Tonotopic organisation
Occipital lobe function
Visual information
- Primary Visual Cortex (V1): receives input from retina via LGN –> damage to V1 results in cortical blindness
- Higher visual areas V2-6: process more complex features, integrate information
Parietal lobe functions
Primary somatosensory cortex
+ proprioception
The limbic system
- forms a border around the brain stem
- important for processing emotional stimuli
Made up of the:
- amygdala
- hippocampus
- hypothalamus
- thalamus
- cingulate gyrus
Amygdala
- important for processing emotional stimuli (as well as learning and memory)
- activated when viewing images that should arouse fear
- damage could result in Urbach-Weith disorder
hippocampus
- long-term episodic memory (specific events)
- damage causes loss of episodic memory
- engram cells:
–> place cells
–> grid cells
–> time cells
role in processing contextual information
Cingulate gyrus
- processing pain and emotional pain (empathetic)
- damage does not prevent the sensation of pain, but the pain is not distressing
basal ganglia
- important for movement, cognition and motivation
- spontaneous, self-generated behaviours
Direct pathway of striatum to thalamus: simple excitatory movement
Indirect pathway of striatum to thalamus: loops between globus pallidus –> learned movement, inhibition of previous response (slows processing)
Caudate nucleus and putamen
- together form the striatum
- where midbrain dopaminergic neurons (from VTA and substantia nigra) terminate
- important for motivation and movement (known as limbic motor interface)
globus pallidus
- part of the relay system between the striatum and the thalamus
- regulation of voluntary movement
- loops between striatum, globus pallidus and thalamus form the indirect, inhibitory pathway
thalamus
relays sensory information to the cerebral cortex
hypothalamus
- neuroendocrine centre
- release of different hormones across subregions
- hypothalamic-pituitary adrenal (HPA) axis controls stress / response to stress via cortisol release
Important role in: motivated behaviour, feeding, drinking, temperature regulation, sexual behaviour, fight/flight, arousal
Ventral tegmental area and substantia nigra
Primary source of dopamine in the brain
Meso-corticolimbic dopaminergic pathways: learned behaviour, reward seeking, substance use disorder
- VTA –> nucleus accumbens
- VTA –> frontal cortex
Nigrostriatal pathway
- substantia nigra –> striatum (caudate nucleus)
Involved in movement, has implications for parkinson’s
Limbic system:
hippocampus, amygdala, cingulate gyrus
striatum
- caudate nucleus
- putamen
Ventral –> euphoria
Dosral –> habit
basal ganglia
- limbic motor interface
- thalamus
VTA and SN?
source of midbrain dopinamergic pathways
Medial Prefrontal Cortex
- necessary for regulating whether learning is inhibited or expressed after extinction (acts as a switch)
in the MPFC: - the prelimbic cortex switches on reward seeking (via the accumbens) and fear seeking via the amygdala
- the infralimbic cortex switches off drug seeking via the accumbens shell, and switches off fear seeking via the amygdala
Prelimbic cortex
necessary for expression of learned fear (does not effect non-associative fear)
infralimbic cortex
necessary for expression of extinction learning
i.e. activation of IL -_> the amygdala facillitates extinction
