Brain Anatomy/Physiology

Question 1

HINDBRAIN

Answer 1

1. as the spinal cord enters the skull, it enlarges and forms the brain stem:
   
   1. medulla
   2. pons
   3. cerebellum
2. MEDULLA: influences the flow of information between the spinal cord and the brain.
   
   1. coordinates swallowing, coughing, sneezing, regulates breathing, heartbeat, and blood pressure.
   2. Damage to the Medulla is often fatal! duh!
3. PONS: connects the two halves of the cerebellum and plays a role in the integration of movements in the right and left sides of the body.
4. **CEREBELLUM: **is important for balance, posture, vital to the performance of coordinated and refined motor movements.
   
   1. works in conjunction with the Basal Ganglia and Motor Cortex.
   2. Basal Ganglia: initiates motor acts, but the cerebellum does the timing and coordination of those acts and corrects errors during the act.
   3. Sensorimotor learning and some aspects of cognitive functioning (attention shifting).
   4. Abnormalities: autism, schizophrenia, and ADHD.
   5. Damage: ataxia or slurred speech, severe tremors, and a loss of balance.
      
      1. similar to drunk, because alcohol exerts a strong effect on the cerebellum.

Question 2

MIDBRAIN

Answer 2

All neural information that travels between the brain and the spinal cord passes throught the midbrain

Comprised of:

1. superior and inferior colliculi
   
   1. visual and auditory information routes
2. substantia nigra
   
   1. motor activity and brains reward system
3. reticular formation
   
   1. extends from the spinal cord through the hindbrain and midbrain into the hypothalamus in the forebrain.
   2. over 90 nuclei involved in respiration, coughing, vomitting, posture, locomotion, and REM sleep.

Reticular Activating System (RAS): vital for consciousness, arousal, and wakefulness.

Screens sensory input (esp. during sleep) and arouses higher centers of the brain when important information must be processed.

Damage to the RAS: disrupts sleep-wake cycle, produce permanent coma-like state of sleep.

general anesthetics work to deactivate the neuron of the reticular formation!

Question 3

FOREBRAIN

SubCortical Structures

Answer 3

SUBCORTICAL

1. Thalamus
2. Hypothalamus
3. Basal Ganglia
4. Limbic System
   
   1. Amygdala
   2. Hippocampus
   3. Cingulate Cortex

CORTICAL

1. Cerebral Cortex
2. Lateralization
3. Frontal Lobe
4. Parietal Lobe
5. Temporal Lobe
6. Occipital Lobe

Question 4

1. THALAMUS

forebrain

Answer 4

1. Thalamus: motor activity, language, memory
2. acts as the relay station
   
   1. transmits incoming sensory information to the appropriate areas of the cortex for all the senses except olfaction.
3. _Wernicke-Korsakoff Syndrome: _ Thiamine deficiency that causes atrophy of neurons in thalamus.
   
   1. associated with chronic alcoholism
   2. Wernicke Encephalopathy: mental confusion, abnormal eye movements, and ataxia (cerebellum of hindbrain)
   3. Korsakoff’s syndrome: severe anterograde amnesia, retrograde amnesia, and confabulation.

Question 5

2. Hypothalamus

forebrain

Answer 5

Hypothalamus: one of the smallest brain structures, but involved in a lot of vital functions: hunger, thirst, sex, sleep, body temperature, movement, and emotional reactions.

1. MOOD: damage to the specific area of hypothalamus can involve uncrontrollable laughter or intense rage/aggression.
2. Monitors the mody’s internal states and initiates responses needed to maintain homeostasis through the ANS, pituitary and other glands.

Suprachiasmatic nucleus (SCN): in hypothalamus and mediates sleep-wake cycle and other circadian rhythms, and seasonal affective dx.

Also contains the mammillary bodies: learning and memory.

Question 6

3. Basal Ganglia

forebrain

Answer 6

Basal Ganglia: has three structures:

1. caudate nucleaus
2. putamen
3. globus pallidus
   
   1. substantia nigra (extends to midbrain)
4. FUNCTION of BG: planning, organizing, coordinating voluntary movement and regulating amplitude and direction of motor actions.
5. Also BG is for sensorimotor learning and in stereotyped, species-specific motor expressions of emotional states (frowning when sad).
6. Disorders that impact the Basal Ganglia: Huntington’s diseas, Parkinson’s disease, Tourette’s, OCD and ADHD all have prominent motor symptoms.
   
   1. ADHD: smaller-than-normal caudate nucleaus, globus pallidus, and prefrontal cortex: poor motor/bx inhibition.
   2. also implicated in mania, depression, and psychosis.

Question 7

4. LIMBIC SYSTEM

forebrain

Answer 7

Limbic System is involved in memory and other cognitive functions but is primarily associated with the:

mediation of emotions!

consists of:

1. Amygdala,
2. Hippocampus,
3. Cinculate Cortex

Question 8

4.1 Forebrain-Limbic-

Amygdala

Answer 8

Amygdala: integrates, corrdinates, and directs motivational and emotional activities.

1. Attaches emotions to memories and recall of emotionally-charged experiences.
2. Flashbulb memories: vivid, detailed memeories of significant, highly emotion-arousing evens.
3. LeDoux: acquisition of classically conditioned emotional responses, which occur when a neutral stimulus is paired with an emotion-arousing neutral stimulus and, results in: the neutral stimulus producing an emotional reaction.
4. Kluver & Bucy Syndrome: bilarteral lesions in the amygdala and temporal lobes of primates substantially reduce fear and aggression, increase docility and compulsive oral exploratory behaviors, alter dietary habits, and produce hypersexuality, psychic blindness (inability to recognize the significance or meaning of events/objects).

Question 9

4.2 Forebrain-Limbic-

Hippocampus

Answer 9

Hippocampus: less directly implicated in emotions than other limbic system structures

1. more associated with learning and memory
2. processing spatial, visual, and verbal information
3. consolidating declarative memories: converting short-term declarative memories to long-term memories .
   
   1. actual storage of the declarative memory takes place elsewhere
4. may be essential for the formation of visual images (w/other medial temporal lobe structures)
5. Bilateral removal of the Medial Temporal Lobes (includes the hippocampus) = treatment for severe epilepsy.
   
   1. causes anterograde amnesia and retrograde amnesia for events occurring up to 3 years prior to the surgery.

Question 10

4.3 Forebrain-Limbic-

Cingulate Cortex

Answer 10

Cingulate Cortex surrounds the Corpus Callosum and is involved in: attention, emotion, and the perception and subjective experience of pain.

1. Anterior Cingulate Cortex: transmission of pain signals and plays an important role in the emotional response to painful stimuli.