Brain Systems and Circuits

Question 1

Frontal lobe functions

Answer 1

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)

Question 2

Temporal lobe function

Answer 2

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

Question 3

Occipital lobe function

Answer 3

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

Question 4

Parietal lobe functions

Answer 4

Primary somatosensory cortex
+ proprioception

Question 5

The limbic system

Answer 5

• forms a border around the brain stem
• important for processing emotional stimuli

Made up of the:
- amygdala
- hippocampus
- hypothalamus
- thalamus
- cingulate gyrus

Question 6

Amygdala

Answer 6

• 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

Question 7

hippocampus

Answer 7

• 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

Question 8

Cingulate gyrus

Answer 8

• processing pain and emotional pain (empathetic)
• damage does not prevent the sensation of pain, but the pain is not distressing

Question 9

basal ganglia

Answer 9

• 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)

Question 10

Caudate nucleus and putamen

Answer 10

• together form the striatum
• where midbrain dopaminergic neurons (from VTA and substantia nigra) terminate
• important for motivation and movement (known as limbic motor interface)

Question 11

globus pallidus

Answer 11

• 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

Question 12

thalamus

Answer 12

relays sensory information to the cerebral cortex

Question 13

hypothalamus

Answer 13

• 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

Question 14

Ventral tegmental area and substantia nigra

Answer 14

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

Question 15

Limbic system:

Answer 15

hippocampus, amygdala, cingulate gyrus

Question 16

striatum

Answer 16

• caudate nucleus
• putamen
  Ventral –> euphoria
  Dosral –> habit

Question 17

basal ganglia

Answer 17

• limbic motor interface
• thalamus

Question 18

VTA and SN?

Answer 18

source of midbrain dopinamergic pathways

Question 19

Medial Prefrontal Cortex

Answer 19

• 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

Question 20

Prelimbic cortex

Answer 20

necessary for expression of learned fear (does not effect non-associative fear)

Question 21

infralimbic cortex

Answer 21

necessary for expression of extinction learning
i.e. activation of IL -_> the amygdala facillitates extinction