Physio - Hindbrain, Midbrain, Subcortical Structures

Hindbrain

MPC, located above spinal cord

Medulla (oblongata)

Pons

Cerebellum

Medulla

-Involuntary mouth and throat functions (swallowing, coughing, sneezing)

-Autonomic survival fxs (HR, BP, breathing)

Pons

-Connects two halves of cerebellum

-Relays messages cerebellum ←→ Cerebral Cortex

-Coordinates movement on both sides of body

-Regulates deep sleep and REM sleep

-Plays a role in breathing

Cerebellum

-Voluntary movement

-Posture and balance

-Procedural/implicit memory (e.g., running, bicycle, playing instrument, driving)

-Some non-motor cognitive functions (e.g., attention, language processing, visuospatial)

Ataxia

Neurological sign of damage to cerebellum

-Lack of voluntary muscle control, poor balance + coordination, jerky eye movements

-Looks like alcohol intoxication

Midbrain

Reticular formation + Substantia nigra (some consider SN to be part of basal ganglia

Reticular formation

-network of neurons between medulla and midbrain

-Muscle tone regulation

-EM coordination

-Pain control

-Consists of RAS

Reticular activating system (aka ascending RAS)

-Mediates consciousness and arousal

-Sleep/wake cycle

-Alerts the CC to incoming sensory signals

Damage to reticular activating system →

→ Comatose state

-stimulating the RAS → awakens the person, or increases alertness

Substantia Nigra

-Connected to basal ganglia (in forebrain)

(Going towards drugs)

-Reward-seeking (addiction)

-Motor control

Degeneration of dopamine-producing cells in SN →

-Motor sxs of Parkinson’s disease

-Slowed movement, tremors, rigidity

Substantia nigra + basal ganglia connection

Motor control

Brainstem (hindbrain + midbrain) damage →

-respiratory/breathing difficulties

-swallowing difficulties

-slurred speech

-balance and coordination issues

-sleep disturbance

-nausea, confusion

-loss of consciousness

Hypothalamus

-Maintains body’s autonomic homeostasis

-BP, HR, breathing rate

-body temperature

-hunger, thirst

-sexual activity, reproduction, growth

-body’s clock, circadian rhythm (suprachiasmatic nucleus)

-Emotions

-Memory (mammillary bodies)

Mammillary bodies

-part of hypothalamus

-Memory, plays a role in it

Suprachiasmatic nucleus

-part of hypothalamus

-Responsible for body’s clock

Hypothalamus → pituitary connection

1.) H releases GnRH, for posterior P to release gonadotropins to regulate testes/ovary functions

2.) H releases oxytocin + vasopressin, which posterior P holds and releases (childbirth, lactation, water balance/reabsorption)

Oxytocin + vasopressin play a role in:

-anxiety/stress, fear

-social bonding, trust/cooperation, social memory

-emotion recognition

-sexual behaviors, aggression

Oxytocin <=> recognition of facial emotions

-Administration of oxytocin in ASD and schizophrenia increases emotion recognition

-In healthy individuals, excess oxytocin impairs recognition, through over-sensitivity/over-detection (esp to disgust, surprise)

-Oxytocin is a hormone and neuropeptide

Thalamus

-Sensory relay station, transmits sensory info to cortex (all but smell)

-Coordinates sensory + motor functioning

-Language and speech

-Declarative memory

Korsakoff syndrome

-Caused by thiamine deficiency d/t alcoholicism → damage to thalamus + mammillary bodies

-Anterograde/retrograde amnesia + confabulation (filling in memory gaps with false info)

Basal ganglia

CPNG

Striatum + Globus Pallidus

-Voluntary movements, initiation and control

-Procedural learning, habits

-Cognitive functions (e.g., attention, decision-making)

-Emotions

Striatum

-Caudate nucleus, Putamen, Nucleus accumbens

-Receives input from cerebral cortex (e.g., thought, movement plan)

Nucleus accumbens

Connects the basal ganglia + limbic system

Globus pallidus

Transmits info to thalamus (and possibly back up to CC)

E.g., CC sends message to move → striatum receives this → globus pallidus sends info to thalamus, back up to CC

Basal ganglia damage →

-Mood disorders

-Schizophrenia

-OCD, ADHD, Tourette’s disorder

-Huntington’s disease, Parkinson’s disease

Amygdala

-Processing, regulating emotions

-Attaching emotions to memories

-Pain modulation, emotion response to pain

-Risk-taking, aggression

Brain areas impacted in risk-taking

Amygdala, insula, ventromedial PFC

Brain areas impacted in aggression/violence

Amygdala, orbitofrontal cortex, anterior cingulate cortex

Kluver-Bucy syndrome

-Originally found in monkeys with amygdala + temporal lobe damage

-Led to reduced fear, hyperseuxality, hyperphagia (excessive eating)

-In humans, temporal lobe + amygdala damage → anxiety, depression, PTSD, ASD, SUDs

Hippocampus

-Transfers declarative memories from ST to LTM

-Spatial memory (memory of spatial characteristics of environment)

Damage to hippocampus + entorhinal cortex (adjacent to hippocampus) →

-Impaired episodic memory + spatial navigation (Alzheimer’s)

-MDD, bipolar

-Schizophrenia

-PTSD (more extreme PTSD ←→ smaller hippocampus)

Effect of high cortisol in the hippocampus

-Impairs retrieval of declarative memories

Cingulate Cortex

-Motivation

-Memory

-Emotions, emotional response to pain

Damage to the cingulate cortex → (effect on pain)

-No emotional distress around pain (still experience pain though)

Brain areas impacted in MDD

-Limbic system (amygdala, hippocampus, Cingulate cortex), PFC, insula, thalamus

-Reduced volume of anterior cingulate cortex

-ACC increases in volume after CBT for depression