Main brain structures NEURO II Exam 2

Facial expression pathway

face area of motor cortex → facial nerve (cranial nerve VII) → superficial facial muscles

Reward circuit/brain self-stimulation

septum/medial forebrain bundle → nucleus accumbens

Fear Pathway low road

sensory organ → thalamus → amygdala (reacts to threat immediately)

Fear pathway high road

sensory organ → thalamus → sensory cortex/hippocampus → amygdala

(conscious response to threat)

Medial amygdala and aggression

medial amygdala → aggression-related processing

(aids in differentiation of sex of other mice for mice & aids in supporting social information relevant to whether aggression occurs)

Ventromedial hypothalamus

medial amygdala → VMH (“Switch” for aggression)

(medial amygdala processes social information → VMH acts as switch for turning aggressive behaviors on/off)

HPA axis (slow stress pathway)

hypothalamus (PVN neuroendocrine cells) → anterior pituitary → ACTH → adrenal cortex → cortisol

(hypothalamus/PVN starts signal → AP releases ACTH → ACTH travels in bloodstream & activates adrenal cortex → adrenal cortex releases cortisol → cortisol supports sustained stress responses & shifts energy usage)

Sympathetic-adrenal pathway (fast stress pathway)

hypothalamus → autonomic preganglionic neurons in brainstem/spinal cord → adrenal medulla → epinephrine + norepinephrine

(hypothalamus initiates rapid stress response → preganglionic neurons carry signal → adrenal medulla releases epinephrine & norepinephrine → body is prepared for “fight-or-flight”

Glucocorticoid receptor feedback

cortisol → glucocorticoid receptors in brain (including hypothalamus) → negative feedback

(aids in regulating cortisol levels → brain can dampen stress response)

Hippocampus & stress regulation

early neglect = reduced hippocampal neurogenesis

Epigenetics & glucocorticoid receptors

early abuse/neglect → altered gene expressions → fewer glucocorticoid receptors → weaker cortisol shutoff

medial temporal lobe for declarative memories

new declarative memories depend on set of structures of medial temporal lobe system (hippocampus, mammillary bodies, dorsomedial thalamus)

Hippocampus vs cerebral cortex

hippocampus forms/consolidates declarative memories

cerebral cortex stores declarative memories in LTM

Patient K.C & semantic vs episodic memories

Patient K.C showed distinction between semantic and episodic memories

Emotion & Memory Connection

epinephrine → amygdala → hippocampus

(emotions enhance memory formation & recall through action of epinephrine on amygdala which then modulates hippocampal activity)