Note
Studied by 19 people
The brain
The brain:
about 100 billion neurons
each neuron can make up to 1000 connections, a total of 100 trillion connections
it is the vital organ and command centre of the body
responsible for all mental processes
regulates survival processes such as breathing, digestion, sleep and blood circulation
grey matter—the brains outer covering where information is stored (the cerebral cortex)
white matter—the neural pathways that connect different parts of the gray matter and other inner structures
Hindbrain, Midbrains, Forebrain
hindbrain:
located at the rear base of the skull and controls basic biological needs for life. It is a primitive part of the brain and the region of the developing vertebrate brain that is composed to the medulla oblongata, the pons and the cerebellum
structures:
Pons (above the medulla): regulates sleep, arousal and respiration, relays information between the cerebellum and the cerebrum
medulla oblongata (middle of the spinal cord): controls involuntary actions such as breathing, heart rate, controls reflexes like swallowing and coughing
Cerebellum (the little brain): regulation and coordination of movement, allows us to make accurate and fluid movements, involved in learning, storage of long term procedural memories
Midbrain: located at the connection between the brain and the spinal cord
connects the hindbrain and forebrain and controls arousal levels, attention and consciousness
its role is to be the brains sensory switchboard which involves receiving and processing sensory information, attention and consciousness
receives messages from our senses, sends these to higher brain regions that deal with these senses
also responsible for auditory and visually processing and eye movement
midbrain reticular formation
through the centre of the midbrain, runs a network of thick names called the reticular formation
its job is to screen information so that only relevant information gets passed to the higher brain, preventing overload
the reticular activating system (RAS) increases or decreases brain arousal, controlling our level of alertness
Forebrain:
the most highly developed and largest part of the brain, affecting feeling thinking and behaviour
cerebral cortex consists of the cerebral hemispheres, which account for two thirds of the brain’s total mass
part of the limbic system, a group of structures in your brain that regulate your emotions, behaviour, motivation and memory
Forebrain structures:
thalamus (structure beneath the cortex): known as the body’s communication centre, processing incoming sensory information and transmits it to other parts of the brain
hypothalamus (small structure that controls the basic survival actions): sleep, regulation of body temperature, hunger and thirst, and expression of emotions
cerebral cortex (outer layer of the forebrain): responsible for receiving information from the environment, for controlling responses and higher order thinking. Involved in memory, language and emotions
the hypothalamus uses cues to tell us we’re hungry (caused by a lower in blood sugar and body temperature)
Cerebral cortex: finish slide 20-24
Responsible for higher brain functions such as perception, conscious thought, memory, language and voluntary movement
has 2 hemispheres (left and right) each with sensory and motor funcitons in theh same place (each hemisphere is further divided into 4 lobes)
Left and right hemispheres:
the hemispheres are connected by the corpus callosum and each hemisphere is dominant in the control of certain tasks
hemispheric specialisation is the concept that each hemisphere has greater control over certain functions, both are involved but each is dominant in specialised functions
the hemispheres have contralateral control of the body which means the left hemisphere controls the right side of the body, and the right hemisphere takes control of the left.
corpus callosum:
the brain has two hemispheres, left and right, almost symmetrical and are joined by the corpus callosum
the corpus callosum is a set of neural fibres that connect the hemispheres
each hemisphere has a central fissure that runs from the top of each hemisphere and down the sides, separating the front of the cerebral cortex from the rear
HOMEWORK
1.Which part controls motor functions? How can knowledge of brain regions support psychologists in treating injuries or psychological disorders?
2.What does Phineas Gage’s case reveal about the relationship between brain injuries and behaviour?
3.How does understanding historical cases like Broca’s help us appreciate the importance of brain localisation today?
4. Watch the Reflex Arc Video on Connect – summarise how reflex arcs work.
Localisation of functions
this refers to the idea that certain functions have certain areas within the brain
this has been supported by brain imaging studies and case studies such as a Phineas Gage
there are 7 areas that we focus on
The Broca’s area
Wernicke’s area
pre-frontal cortex
primary motor cortex
primary sensory cortex
primary auditory cortex
primary visual cortex
Broca’s area and Wernicke’s area:
Broca:
location is adjacent to the primary motor cortex in the left frontal lobe
the function is that it controls the fine muscles responsible for clear and articulate speech
impairment caused when damage is the impairment in the ability to produce articulate speech (broca’s aphasia)
Wernicke:
locaiton is adjacent to the primary auditory cortex in the left temporal lobe
responsible for the understanding of language and the production of meaningful speech
impairment caused when damage is the inability to understand language and produce meaningful speech (wernicke’s aphasia)
Cortices
pre frontal cortex (the front layer of the frontal lobe that coordinates executive functions such as predicting consequences of behaviour, recognising and regulating emotions
primary motor cortex (the strip running through the frontal lobes that control voluntary movement of the body. Different zones within the cortex correspond to various parts of the body, with size of zone representing the importance of the body part)
primary sensory cortex (somatosensory) (the strip running through the parietal lobes that registers and processes sensory information
primary auditory cortex (an area within both temporal lobes that register the processes auditory information that is received from the ears)
primary visual cortex (an area with the occipital lobes that register and process visual information that is received from the eyes)
Reflex arc
an automatic response that happens without conscious thought
reflexes help protect us by allowing responses to danger
Steps:
stimulus-something that triggers a reaction, e.g., touching a hot stove
receptor-sensory neurons detect the stimulus
sensory neuron-sends the message to the spinal cord
interneuron-processes information and sends instructions
motor neuron-carries the command to the muscles
effector (muscle)-responds by moving (pulling the hand away)
the brain is not involved in the immediate response, which is what makes the reflexes so fast
1.Which part controls motor functions? How can knowledge of brain regions support psychologists in treating injuries or psychological disorders?: The frontal lobe controls motor functions and voluntary movements. Knowledge of the brain regions support psychologists in treating injuries or psychological disorders by allowing them to understand the neural mechanisms in the region and tailor treatments accordingly.
2.What does Phineas Gage’s case reveal about the relationship between brain injuries and behaviour? Phineas Gage’s case reveals how theres a strong link between brain injuries an d behavioural changes. His case is one of the first examples of evidence indicating that damage to the frontal lobe can alter personality, emotions and interactions
3.How does understanding historical cases like Broca’s help us appreciate the importance of brain localisation today? Historical cases like Broca’s help us appreciate the importance of brain localisation today as he’s identified what certain parts of the brain are responsible for and how they can impact us. Through his case, he identified how the left frontal lobe, known as Broca’s area, is responsible for language production and motor speech. His patients aphasia in speech and damage to the left frontal lobe allowed for a further understanding in the functions of certain parts of the brain
4. Watch the Reflex Arc Video on Connect – summarise how reflex arcs work.: The reflex arc works through the following steps. It requires stimulus, something that will trigger a reaction, e.g., touching a hot stove, or someone poking your eye. This stimuli is then detected by sensory neurons, which then sends the message to the spinal cord. This message is processed by interneurons which sends instructions which then motor neurons carry out to the muscles. The muscle then responds by moving, e.g., pulling the hand away, and blinking. The reflex arc does not involve the brain in the immediate process, which is why reflexes are so fast. The reflex arc also includes both the PNS and the CNS (sensory neurons and motor neurons)
Phineas Gage’s case:
born 1823, died 1860
in 1848, he had a workplace accident in which an iron rod entered and exited his skull
the rod penetrated his left cheek and tore through his brain
he survived the incident however his personality changed as a result. he was still able to speak and wlak to a nearby cart so he could be taken to a doctor, he was also still conscious and able to recount the names of his co workers
this led to a greaty understanding of the brain regions involved in personality, mainlly the frontal lobe
some believe that if the rod had penetrated other areas of the head he may have died
after the accident, he went from a hardworking pleasant man to an aggressive heavy drinker
from energetic and motivated, he was ‘no longer gage’
the iron rod destroyed about 11% of the white matter in his frontal lobe and 4% of his cerebral cortex
his case had a large influence on early neurology
specific changes observed in his behaviour pointed to theories about ht localisation of brain functions, or the idea that certain functions are associated within specific areas of the brain
Broca’s historical case:
in 1861 french surgeon Paul Broca, described the case of a patient with Broca aphasia (difficulty producing speech) and damage to the left frontal lobe, known as Broca’s area, establishing a link between specific brain regions and language function
the patient was named tan because he could only repeat the syllable tan
broca observed the difficulty in producing speech despite retaining the ability to understand language (wernicke)
after the death of the patient, broca performed an autopsy and found. alesion in the left frontal lobe which Broca identified as the region responsible for speech production and motor speech
the aphasia caused by damage to broca’s area (left frontal lobe) is known as broca’s aphasia, characterised by difficulty in producing fluent and grammatically correct speech