Week 1-Brain structure and function

Question 1

Define Biopsychology

Answer 1

the scientific study of the biology of behaviour with a biological approach to psychology AND denotes (indicates) the biological drivers of thought and behaviour. (also known as psychobiology OR behavioural neurosciences)

Question 2

Define Neuroanatomy

Answer 2

The study of the nervous system structure (basis of this week’s notes)

Question 3

Define Neurophysiology

Answer 3

The study of the functions + activities of the nervous system (basis of this week’s notes)

Question 4

Define Neurochemistry

Answer 4

The study of the chemical basis of neural activity

Question 5

Define Neuroendocrinology

Answer 5

The study of interactions between the nervous system and the endocrine system.

Question 6

Define Neuropathology

Answer 6

The study of nervous system disorders

Question 7

Define Neuropharmacology

Answer 7

The study of the effects of drugs on neural activity (neuro=nerves)

Question 8

What is the brain and what does it allow us to achieve?

Answer 8

■A complex pinkish-grey mass of tissue that weighs about 1.5kg
■Houses the mind of a human being – memories, thoughts and emotions. Wishes, aspirations, disappointments – the capability of consciousness, self-reflection and free will.
■Enabled us to be dominant creatures on earth – artistic, scientific, medical and technological achievements

Question 9

Why are we able to achieve what we can because of the brain?

Answer 9

This is because of the complexity of our brains:
-100 billion neurons (lecture 2)
-Each projecting to 5000-10,000 other neurons (i.e., literally trillions of connections – synapses)

Question 10

How does brain research benefit us all?

Answer 10

It allows us to understand human afflictions (e.g., mental illness, degenerative disease) to try and improve treatment

Question 11

History: What did Plato (429-348 BC), Ancient Greece propose?

Answer 11

The brain is the organ of reasoning (previously believed to be the heart)

Question 12

History: What did Galen (AD 130-200), a physician of the Roman Empire propose?

Answer 12

proposed a theory that brain function is based on ventricles – not allowed to perform human dissection in Rome (body seen as sacred), so observed cattle and oxon

Question 13

When were the first drawings of the brain drawn?

Answer 13

Late 15th century (drawn by Leonardo da Vinci)

Question 14

Who is René Descartes (1596-1650) and what did he propose?

Answer 14

A French Philosopher and mathematician – he thought, therefore he was “Cognito; ergo sum” (I think therefore I am)
 Proposed that mind and body interacted in the pineal gland. Also realised much behaviour was mechanical, not requiring mental processing
Developed the concept of the automatic reflex – the basis of our modern understanding of sensory nerves conveying messages to the brain
Importantly some behaviour is reflexive – the mind is not involved (although it feels pain, and is aware of what happened) but NOT A CAUSE of behaviour e.g., moving hand away from a candle
Descartes paved the way for the scientific and non-secular approach to understanding human physiology (religious or spiritual matters)

Question 15

How many Nobel peace prizes have been awarded in neuroscience?

Answer 15

50

Question 16

What does the central nervous system divide into?

Answer 16

1. brain
2. spinal cord

Question 17

How does the peripheral nervous system divide?

Answer 17

1. autonomic nervous system (communicates with internal organs and glands):
   -sympathetic division (arousing)
   -parasympathetic division (calming)
2. somatic nervous system (communicates with sense organs and voluntary muscles):
   -sensory (afferent aka enter) nervous system (sensory input)
   -motor (efferent aka exit) nervous system (motor input)

Question 18

What are the sensory organs?

Answer 18

eyes, ears, nose, tongue, and skin

Question 19

True or false: Both ANS and SNS contain afferent and efferent nerves + give an example in the SNS

Answer 19

True, Example:
*Sensory (afferent) nerve senses hot flame on the skin (external sense organ). Afferents sense the heat and send rapid messages to the spinal cord – conveying the message of heat pain!
*Motor (efferent) nerves respond by sending signals from CNS to muscles, to move the hand away from the flame

Question 20

What’s the ANS?

Answer 20

Some motor actions are involuntary and “automatic” e.g., heart and breathing (we don’t have to consciously think about these)

Question 21

What’s the SNS?

Answer 21

Controls the voluntary movements part e.g., moving your hand away from the flame.

Question 22

How many types of efferent nerves does the ANS have?

Answer 22

2 (Projecting from the CNS to internal organs)

Question 23

What’s the Sympathetic nervous system?

Answer 23

Autonomic motor nerves that prepare us for action (fight or flight)
*Think of this as responding to a stressor (a lion) e.g., heart rate increases
*MOBILISES energy

Question 24

What’s the Parasympathetic nervous system?

Answer 24

Autonomic motor nerves that prepare us to relax
*Your peaceful restful state e.g., increases digestion
*CONSERVES energy

Question 25

What are directional terms in neuroanatomy?

Answer 25

*Terms for a 3D coordinate system to help neuroanatomists explain and navigate where something is in the brain
*These are described in relation to the orientation of the neuraxis (which is the direction in which the CNS lies in relation to the spinal cord)

Question 26

What’s bipedalism?

Answer 26

The fact you’re standing on two feet (means the brain isn’t in a straight line with the spinal cord)

Question 27

Directional terms: Name the 3 axes used in animals

Answer 27

1.Anterior-posterior
2.Dorsal-ventral
3.Medial-lateral

Question 28

Define dorsal and ventral in animals

Answer 28

D-Toward the back of the body,
or towards the top of the head
V-Toward the front (belly) of the
body or towards the bottom of the head

Question 29

Define rostral and caudal in animals

Answer 29

R-Toward the front end of the body (nose)
C-Towards the tail

Question 30

Define medial and lateral in animals

Answer 30

Medial = toward the midline
Lateral = away from the midline

Question 31

Define dorsal and ventral in humans

Answer 31

D: Toward the back of the body, or towards the top of the head (because of right angle neuraxis)
V: Towards the front (belly) of the body or towards the bottom of the head

Question 32

Define rostral and caudal

Answer 32

R: Towards the nose
C: Towards the feet (humans) or tail

Question 33

Define proximal and distal

Answer 33

Proximal = close to CNS e.g. shoulders
Distal = far (distant) from CNS e.g. fingers

Question 34

Define Bilateral/ Ipsilateral/Contralateral

Answer 34

■ Bilateral: On both sides of the
body or head
■ Ipsilateral: On the same side of the body or head
■ Contralateral: On the opposite side of the body or head

Question 35

True or false: Directional terms can combine

Answer 35

True e.g., Ventromedial (towards the bottom of the head towards the midline), Dorsolateral, Ventrolateral, Dorsomedial

Question 36

Directional terms: Define horizontal, coronal and saggital

Answer 36

H: just horizontal
C: cut from front to back like a slice
S: cut like an apple in half

Question 37

Directional terms: Define cross-section

Answer 37

A slice taken at right angles to
the neuraxis.

Question 38

Define Midsaggital plane

Answer 38

the plane through the neuraxis perpendicular to the ground; divides the brain into 2 symmetrical halves.

Question 39

What’s Meninges and how does it protect the brain?

Answer 39

-different protective membranes
*For obvious reasons the brain and spinal cord are well protected by bone and 3 protective membranes (membrane = selective barrier, which allows some things to pass but not others)
*Dura mata
*Arachnoid membrane
*Subarachnoid space (between arachnoid and pia mater where CBF passes through)
-Meningitis

Question 40

What’s Cerebrospinal Fluid and how does it protect the brain?

Answer 40

*Fluid that fills the subarachnoid space, the spinal cord and ventricles of the brain
*CBF provides cushioning and support for the brain.
*People who have this drained suffer headaches and pain because their sensitive brains are not protected by the fluid.
*Excess CBF is continually absorbed into subarachnoid space and sinuses which run through dura mata and drains into the jugular vein
*If obstructed (e.g., a tumour between ventricles) CBF can build up in ventricles leading to brain expansion. A condition called hydrocephalus (water head)

Question 41

What’s the blood-brain barrier and how does it protect the brain?

Answer 41

*A semi-permeable membrane, which separates blood from the CBF, providing a barrier that prevents many toxins from entering the brain from the bloodstream (using endothelial cells)
*The degree to which therapeutic or recreational drugs (psychoactive drugs) work, depends on the ease with which they can cross the BBB

Question 42

What 5 divisions/major structures of the brain are evident in from embryonic development to adulthood?

Answer 42

1.Myelencephalon –medulla - largely comprises tracts between the brain and spinal cord. (Covered in myelin which is white insulated matter on the neurons hence the name)
2.Metencephalon - pons and cerebellum.
3.Mesencephalon - tectum and tegmentum.
4.Diencephalon – thalamus and hypothalamus.
5.Telencephalon – cerebral cortex, limbic system and basal ganglia.

Question 43

What’s the Myelencephalon (Medulla)?

Answer 43

*Part of the hindbrain – most posterior part of the brain (brain stem)
*Oldest part = medulla oblongata (long marrow) – controls breathing, heart rate, salivation, vomiting
*If brain is cut above the medulla basic heart rate and breathing are maintained. Damage to medulla = fatal
*Contains the reticular formation (involved in sleep, attention movement, and cardiac, circulatory and respiratory reflexes)

Question 44

What’s the Metencephalon?

Answer 44

• Part of the hindbrain – most posterior part of the brain
• Contains pons and cerebellum
• Pons (bridge) – enlargement of medulla, contains pontine nuclei – contains coeruleus and dorsal raphe = origin of noradrenergic and serotonergic containing fibrers in the forebrain
• Cerebellum (little brain) important for sensorimotor control – control of movements
• Cerebellum damage can cause problems with decision-making and language too

Question 45

What’s the Mesencephalon (midbrain)?

Answer 45

*Part of the midbrain –two divisions (tectum and tegmentum)
*Tectum: dorsal of midbrain. Inferior colliculi (auditory function), superior colliculi (visual-motor function)
*Tegmentum: contains PAG– Primary control centre for descending pain modulation (contains enkephalins which are an endogenous neurochemical which binds to opioid receptors)
Endogenous=produced within us
*Substantia nigra – important component of the sensory-motor system

Question 46

What’s the Diencephalon (forebrain)?

Answer 46

*Up to this point brain could be likened to a tube that has evolved and enlarged from the spinal cord. Forebrain mushrooms out from so that it covers and surrounds the
older ‘tubular’ brain, and adds greater complexity and new structures – e.g., hypothalamus and thalamus
* Thalamus (Greek: inner chamber) – relays sensory signals from skin to prepare motor signals to the cerebral cortex. Also involved in sleep, consciousness, alertness
* Hypothalamus – important for motivated behaviours (eating, sleeping and sexual behaviour)

Question 47

What’s the Telencephalon?

Answer 47

• Everything else! Mediates most of the brain’s complex functions – voluntary movement, sensory input, cognitive processes – learning, speaking, problem-solving
• Contains cerebral cortex AND subcortical structures – as well as important fibre bundles

Question 48

Telencephalon: What’s the Cerebral Cortex?

Answer 48

*Composed of small unmyelinated neurons
*Grey matter (other layers are composed of large myelinated axons and are white matter)
*Convolutions (dips in the brain) serve to increase surface area
*Large convolutions = fissures
*Small convolutions = sulci
*Ridges between fissures and sulci = gyri
*Longitudinal fissure separates hemispheres (it remains connected by cerebral commissure, inc corpus callosum)
*Contains the NEOCORTEX, and subcortical structures (hippocampus, limbic system, basal ganglia)

Question 49

Subcortical structures – What’s the hippocampus?

Answer 49

*Has 3 major layers
*Located at the medial edge of the cerebral cortex, folds back on itself in the medial temporal lobe
* Hippocampus means seahorse
*Has a major role in memory (spatial location memory)

Question 50

Subcortical Structures – What’s the limbic system?

Answer 50

■Limbic system – circuit of midline structures that circle the thalamus
■ regulation of motivated behaviours and consists of mammillary bodies,
hippocampus, amygdala, fornix, cingulate, septum

Question 51

Subcortical Structures – What’s the Basal ganglia?

Answer 51

• Motor system.
• Consists of amygdala, striatum (caudate nucleus + putamen), globus pallidus
• Extrapyramidal motor system (output fibres do not cross the pyramidal regions of the medulla)
• Degeneration of the nigral-striatal pathway causes rigidity, tremor and slow movement in Parkinson’s disease
• Involved in the coordination of automated (without thinking) smooth, fluent movement.

Question 52

Why has the neocortex got its name?

Answer 52

• It is the newest part of the cerebral cortex to evolve
• Cerebral cortex = largest part of telencephalon, composed of grey matter. Neocortex = largest part of cerebral cortex (90% of cerebral cortex is neocortex in humans). Other part is allocortex (contains hippocampus) I.e., subcortical structures

Question 53

What is the main difference with the neocortex?

Answer 53

• Main difference is that neocortex has six layers – the most developed in its number of layers and organisation of the cerebral tissues (specific to mammals)
• Humans have large neocortex ratio, which correlates with complexity of behaviour. For a large neocortex to evolve, the brain must evolve in size to support it
• Central and lateral fissure divide each hemisphere into 4 lobes (frontal, parietal, temporal and occipital)
• lobes are not functional units

Question 54

What are the 4 lobes of the cerebral cortex/neocortex and their functions?

Answer 54

1. frontal lobe: motor cortex (precentral gyrus) and complex cognitive functions (frontal cortex)
2. temporal lobe: hearing, language, complex visual patterns and memory
3. occipital lobe: visual processing
4. parietal lobe: somatic sensations e.g., touch (postcentral gyrus) and orientation (location of objects)

Question 55

Explain the case of HM and the amnesic effects of bilateral medial temporal lobectomy

Answer 55

 An epileptic who had his temporal lobes removed in 1953 (27 years old)
 In 11 years preceding surgery averaged one generalised seizure p/w, and several focal seizures per day (despite anticonvulsants)
 His generalised seizures stopped, and partial seizures reduced massively. Left surgery well-adjusted, normal perceptual and motor ability, normal intelligence…Memories for events predating surgery intact (more or less), short term memory pretty good too.
 BUT…total inability to form new long-term memories. In effect, H.M became suspended in time that day in 1953, when he regained his health, but lost his future

Question 56

What did EEGs previously suggest about seizures?

Answer 56

EEG suggested seizures arose from foci in both left and right temporal lobes. Removal of one medial temporal lobe had proved effective in patients with unilateral temporal lobe focus – thus a decision was made to remove medial portions of both temporal lobes inc hippocampus, amygdala

Question 57

Explain the case of Phineas Gage: neuroscience’s most famous patient

Answer 57

 13 sept 1848 (25 years old) Gage began tamping before sand. The tamping iron struck a rock, causing a spark to light the powder the explosion propelled his tamping iron through his head.
 Entered under his left cheekbone, penetrated base of skull behind left eye socket, emerged at the top of the skull
 Despite his horrific injury, within minutes Gage was sitting up in a cart, conscious and recounting what had happened
 In 1868 Harlow wrote a report on the ‘mental manifestations’ of Gage’s injuries. He described Gage as “fitful, irreverent, indulging at times in the grossest profanity… capricious and vacillating” and being “radically changed, so decidedly that his friends and acquaintances said he was ‘no longer Gage’.”
 The damage to Gage’s frontal cortex resulted in a loss of social inhibitions. Gage’s injuries provided some of the first evidence that the frontal cortex was involved in personality and behaviour.

Question 58

What is the primary goal of psychobiologists?

Answer 58

To use this knowledge of brain anatomy (from the level of cellular architecture to distinct structures and regions and how they interact and connect with one another) to improve our understanding
of BRAIN FUNCTION.