Physio - Brain Regions/Functions – Hindbrain, Midbrain, and Subcortical Forebrain Structures

The brain is divided into three regions, the _____, _____, and _____.

hindbrain, midbrain, and forebrain

the _____ and _____ constitute the brainstem

hindbrain and midbrain

brainstem damage depends on its location, but symptoms include

respiratory problems, difficulty swallowing, slurred speech, problems with balance and coordination, nausea, sleep disturbance, confusion, or loss of consciousness

the forebrain includes….

subcortical structures (hypothalamus, thalamus, basal ganglia, amygdala, cingulate cortex, hippocampus) and the cerebral cortex

the hindbrain includes the (3)

medulla oblongata, pons, cerebellum

the midbrain structures include (2)

reticular formation

substantia nigra

subcortical forebrain structures include (6)

hypothalamus, thalamus, basal ganglia, limbic system (amygdala, cingulate cortex, hippocampus)

what is part of the limbic system (3)

amygdala, cingulate cortex, hippocampus (all of these are subcortical forebrain structures)

what is the medulla responsible for

involuntary mouth and throat movements (swallowing, coughing, sneezing)
respiration

heart rate

blood pressure regulation

what can disrupt the functioning of the medulla

injury, diseases, drugs (especially opioids)
can result in death

nicknames for subcortical system and cortical system

subcortical = “survival system”

cortical = “conscious emotional system”

Pons

connects the two halves of the cerebellum

relays messages between cerebellum and cerebral cortex

coordinates movements on either side of the body

plays a role in: respiration, deep sleep, REM sleep

cerebellum

voluntary movement, balance, posture, non-motor cognitive function (attention, linguistic processing, visuospatial), procedural memories (e.g., running, playing an instrument, driving), and other implicit memories (that operate on an unconscious, automatic level).

damage to the cerebellum can cause ___

ataxia = lack of muscle control, impaired balance, slurred speech, nystagmus (jerky eye movements), blurred or double vision (symptoms associated with alcohol intoxication)

reticular formation (including RAS/ARAS)

part of the midbrain; consists of a network of neurons that extend from the medulla into the midbrain

function: muscle tone, coordinating eye movements, controlling pain, sleep and consciousness

contains the RAS: reticular activating system (also called the ascending reticular activating system or ARAS) — mediates consciousness and arousal, controls sleep/wake cycle, alerts cerebral cortex to incoming sensory signals

damage to the RAS causes comatose state

direct stimulation to the RAS by sensory input can awaken a sleeping person or cause them to be more alert

substantia nigra

midbrain

reward-seeking, drug addiction, and (through its connection basal ganglia) motor control

degeneration of dopamine-producing cells in the substantia nigra causes

Parkinson’s disease: slowed movement, tremors, rigidity

forebrain includes cortical and subcortical regions - describe the difference and list the brain areas included in each region

cortical = higher-order cognitive functions like reasoning, language, sensory processing, and voluntary movement

• cerebral cortex (frontal, parietal, occipital, and temporal lobes)

subcortical = basic processes like motor control, memory, and emotions

• limbic system (amygdala, hippocampus), basal ganglia, thalamus, hypothalamus

hypothalamus

subcortical forebrain

function: maintains homeostasis, regulates survival functions through its influence on the autonomic nervous system and pituitary gland (body temperature, blood pressure, heart rate, respiration, thirst, hunger, growth, sex, reproduction, response to stress), emotion, memory, circadian rhythm

how does damage to hypothalamus impact emotions?

aggression and rage, crying, or laughter

what is the role of hypothalamus on sleep and memory?

contains mammillary bodies (which play a role in memory) and suprachiasmatic nucleus (SCN) which serves as the body’s biological clock and regulates sleep/wake cycle and other circadian rhythms

how does the hypothalamus influence the pituitary gland?

1. produces hormones that stimulate or inhibit hormones produced by the anterior pituitary (responsible for gonadotropin-releasing hormone [GnRH] and the development or secondary sex characteristics)

2. sends oxytocin (uterine contractions, lactation) and vasopressin (regulates water in the body and controlling water reabsorption in the kidneys) to the posterior pituitary

research on oxytocin and vasopressin

• oxytocin and vasopressin play a role in social bonding, trust, social recognition, social memory, aggression, and psychosocial stress

  • e.g., elevated oxytocin inhibits HPA axis and sympathetic nervous system responses to stress which reduces HR, blood pressure, and cortisol levels

• oxytocin has beneficial effects on ASD, schizophrenia and other disorders involving recognizing emotions in facial expressions (but in healthy adults, it either doesn’t make a difference or it made them overly sensitive to facial expressions)

thalamus

“relay station” that receives and transmits sensory information to the cortex for all senses EXCEPT smell
also coordinates sensory and motor function, language and speech, and declarative memory

thiamine deficiency in the thalamus is associated with

Korsakoff syndrome

• anterograde amnesia, retrograde amnesia, and confabulation (filling memory gaps, especially gaps in episodic memory, which false information that the person believes is true)

• often caused by alcoholism which damages neurons and mammillary bodies in the thalamus

basal ganglia (the 4 parts)

1. caudate nucleus, putamen, and nucleus accumbens = striatum (receives input from the cerebral cortex)

2. globus pallidus: transmits information to the thalamus

disorders associated with the basal ganglia

mood disorders, schizophrenia, ADHD, OCD, Tourette’s, Huntington’s, Parkinson’s

structures in the limbic system are primarily involved in the role of

emotion

mammillary bodies are responsible for

memory

the suprachiasmatic nucleus is responsible for

sleep

functions of the basal ganglia

voluntary movement

procedural and habit learning

nondeclarative memory

cognitive functioning (e.g., attention and decision-making)

emotion

limbic system structures

amygdala, cingulate cortex, hippocampus

functions of amygdala

emotions: fear, anger, anxiety, joy, and others. responsible for recognizing fear and other emotions in facial expressions; and attaching emotions to memory.

memory: flashbulb memories

pain: modulation and emotional responses to pain (anxiety, fear)

behavior: risk raking (Weller et al 2009)

flashbulb memory

vivid memories for surprising and shocking events

Weller et al. (2009) research on the amygdala

amygdala is involved in risk taking

Kluver and Bucy (1939) research on the amygdala, hippocampus, and temporal lobe

bilateral lesions in rhesus monkey caused Kluver-Bucy syndrome: hyperphagia (extreme hunger), hyperorality (putting things in mouth), reduced fear, hypersexuality, visual agnosia (psychic blindness - recognizing objects by sight)

linked to social anxiety/other anxiety disorders, MDD, PTSD, autism, substance use disorders

cingulate cortex functions

motivation, memory, emotions (including emotional reactions to pain)

damage to cingulate cortex

they will feel pain but are not emotionally distressed by it

disorders associated with cingulate cortex (and related research)

MDD

research shows that reduced anterior cingulate cortex (ACC) volume is associated with depression, and that improvements in depressive symptoms following participation in CBT are associated with increases in ACC volume

what makes the hippocampus different from other limbic structures?

it is involved more in memory and less in emotions

functions of hippocampus

memory: transferring declarative memories from short-term to long-term memory, spatial memory (memory for the spatial characteristics of the environment)

emotions: also plays a small role in cortisol/stress

research on damage to hippocampus

linked to:

Alzheimer’s (episodic and spatial memory impairment)

Cushing’s syndrome (increases in cortisol levels in hippocampus) impairs retrieval of declarative memories

PTSD: the more extreme their stress, the smaller their hippocampus was (unclear whether trauma causes reduction in hippocampal volume vs reduced hippocampal volume as risk factor for PTSD)

also related to MDD, bipolar disorder, and schizophrenia