Brain and Behaviour

Question 1

Central Nervous System

Answer 1

• Central Nervous System: The peripheral nervous system reflects a complex job of neural wiring, but the human central nervous system is probably the most remarkable feat of electrical engineering ever accomplished. Under-standing the way it functions requires some knowledge of its evolution.

• The brain and spinal cord
• Like a living fossil record
• The more we go down the more we see ancient structures that evolved hundreds of millions of years ago and were shared
• The spinal cord carries out reflexes, transmits sensory information to the brain and transmits messages from the brain to the muscles and the organs. Each of its segments controls sensation and movement in different parts of the body.

Question 2

Design of human nervous system *too long

Answer 2

-like that of other animals, reflects its evolution. Early precursors to the first vertebrates (animals with spinal cords) probably reacted with reflexive responses to environmental stimulation at specific points of their bodies. The most primitive vertebrate brain, or brainstem, included a forebrain (specialised for sensing nearby stimuli, notably smells and tastes), a midbrain (specialised for sensation at a distance, namely vision and hearing) and a hindbrain (specialised for control of movement). This rough division labour persists in contemporary vertebrates, including humans. The forebrain of humans and other contemporary vertebrates includes an expanded cerebrum, with a rich network of cells comprising its outer layers or cortex, which allows much more sophisticated sensory, cognitive and motor processes.

Question 3

Three Parts of the Brain

Answer 3

The Brain

• Consists of three parts 1) the hindbrain 2)the midbrain 3)the forebrain.

Question 4

What is the hindbrain

Answer 4

• The hindbrain

• Directly above the spinal cord
• Sustain life by controlling supply of air and blood cells to the body, and regulate arousal level

Question 5

Medulla (hindbrain)

Answer 5

• Comprised of the medulla (an extension of the spinal cord that links the cord to the brain, essential to life→ can’t live without it),
  o 3.5 cm long and 2cm wide
  o Essential to life
  o Controls heartbeat, circulation and respiration

Question 6

Cerebellum (hindbrain)

Answer 6

• Cerebellum (large structure at back of brain that is involved in movement).
  o Sensory and cognitive processes→ learning to associate a stimulus with another
  o Involved in coordinating smooth, well sequenced movements
  o Staggering speech after drinking too much can be stemmed from effects of the cerebellum

Question 7

Reticular Formation (hindbrain)

Answer 7

• Reticular Formation
  o Diffuse network of neurons that extends from the lowest parts of the medulla in the hindbrain to the upper end of the midbrain
  o Sends axons to many parts of brain and spinal cord
  o Major functions include, maintaining consciousness, regulate arousal levels and modulate activity of neurons throughout the central nervous system
  o Also appears to help higher brain centres to integrate information from different neural pathways (such as sounds, associated images)

Question 8

Tectum (midbrain)

Answer 8

o The tectum is involved in orienting vision and hearing.

Question 9

Tegmentum (midbrain)

Answer 9

o The tegmentum involves parts of the recticular formation and other neural structures. Serves many functions related to movement

Question 10

The Forebrain

Answer 10

• The forebrain is involved in complex sensory, emotional, cognitive and behavioural processes, consists of hypothalamus, thalamus and cerebrum.

Question 11

Hypothalamus (forebrain)

Answer 11

o Hypothalamus
• Only accounts for 0.3% of brains total weight
• Tiny structure helps regulate behaviours from sleeping and eating to sexual activity and emotional experience
• In non-human animals related to behaviours such as reaction to predators
• Works closely with the pituitary gland and provides link between nervous system and endocrine system
• When people undergo stressful experiences (such as taking an exam or being in a heated argument), hypothalamus activates the pituitary which puts body on high alert
• Homeostasis→ keeping vital processes such as body temp, blood sugar (glucose) level and metabolism (use and storage of energy) within a fairly narrow range

Question 12

Thalamus (Forebrain)

Answer 12

o Thalamus
• Set of nuclei located above the hypothalamus
• Process sensory information as it arrives and transmit this information to higher brain centres
• Like a switchboard for routing info from neurons connected to visual, auditory, taste, touch and touch receptors to appropriate regions of the brain
• Not only route messages but filter them

Question 13

The limbic system (Forebrain)

Answer 13

o The limbic system
o Losely connected network of structures, plays an important role in learning and memory, and in the expression of emotion
o Two important structures are the amygdala and the hippocampus
o Hippocampus plays important role in memory, particularly in consolidation of new memories (learning)
o The amygdala, located immediately in front of the hippocampus serves vital role in processing emotional information, particularly the learning of fear responses

Question 14

The limbic system Hippocampus (Forebrain)

Answer 14

Hippocampus plays important role in memory, particularly in consolidation of new memories (learning)

Question 15

The limbic system] Amygdala (Forebrain)

Answer 15

The amygdala, located immediately in front of the hippocampus serves vital role in processing emotional information, particularly the learning of fear responses

Question 16

The basal ganglia (forebrain)

Answer 16

o Set of structures, including the putamen and caudate nucleus located near the thalamus and the hypothalamus
o Damages to structures can affect posture and muscle tone or cause abnormal movements
o Implicated in Parkinson’s disease
o Damage can also lead to variety of emotional, social and cognitive impairments. E.g may have difficulty recognising that a subtle change in another person’s tone of voice reflects sarcasm- the kind of judgements the rest of us can make without a moment’s thought.

Question 17

The cerebral cortex

Answer 17

• The cerebral cortex
o Consists of 3mm thick layer of densely packed interneurons; it is greyish in colour and highly convoluted (filled with twists and turns).
o Preforms 3 functions
o 1) Allows flexible construction of sequences of voluntary movements involved in activities such as changing a tyre or playing a piano concerto
o 2) Permits subtle discrimination against sensory patterns; without words like gene and gem would be indistinguishable
o 3) Makes possible symbolic thinking- ability to use symbols such as words or pictorial signs (like a flag) to represent an object or a concept with a complex meaning. Enables people to have conversations that do not exist or are not presently in view; foundation of human thought and language

Question 18

Occipital lobes (cerebral cortex)

Answer 18

• The occipital lobes located in rear portion of cortex are specialised for vision. Concerned with many aspects of vision

Question 19

Parietal lobes (cerebral cortex)

Answer 19

• The parietal lobes are located in front of the occipital lobes. Involved in several functions, including touch, detecting movement in environment, locating objects in space and experiencing one’s own body as it moves through space. Also involved in complex vision processing, particularly posterior (back) regions nearest to occipital lobes
o Somatosensory cortex lies directly behind central fissure, different receive information from different parts of the body

Question 20

Frontal lobes

Answer 20

• The frontal lobes are involved in movement, attention, planning, social skills, abstract thinking, memory and some aspects of personality.
o Motor cortex, primary zone, initiates voluntary movement.

Question 21

Cerebral Lateralisation

Answer 21

• Cerebral Lateralisation
o Lateralised: Localised to one or the other side of the brain
• Most functions that are popularly considered to be lateralised are actually represented on both sides of the brain in most people
• However some division of labour between hemispheres
• Right handed people, the left hemisphere tends to be more dominant for language, logic, complex motor behaviour and aspects of consciousness (particularly verbal)
• Left hand functions analytical, breaking down thoughts and perceptions into component parts and analysing the relationships among them
• Right hemisphere tends to be more dominant for non-linguistic functions, forming visual maps of the environment. Studies indicate that involved in recognition of faces, places, and non-linguistic sounds such as music
• Split-brain studies show when corpus callosum is surgically cut, blocking communication between two hemispheres. They generally appear normal however each hemisphere of brain can operate independently but oblivious to what the other is doing.