Memory

           Memory is an umbrella term for functions such as encoding, retrieving, recalling and recognising information. It is commonly divided into two different types, long-term memory (LTM) and short-term memory (STM). STM allows recall for a period of several seconds to a minute without rehearsal, its capacity is very limited. LTM however has a much larger capacity, meaning one can remember a much larger quantity of information and recall can last for an unlimited period of time, sometimes an individuals lifetime. The hippocampus and the frontal lobes are both implicated in memory, another area is the diencephalon consisting of the thalamus and the hypothalamus. Damage to any of these areas can result in memory loss and result in a memory disorder such as Amnesia. Amnesia is a disorder which is characterised by a loss of memory. There are two sub types, Retrograde amnesia refers to individuals who suffer a loss of memory for events that occurred before the trauma (loss of LTM) where as Antrograde amnesia refers to a loss of ability to learn new information and an inability to make long lasting memories post trauma however, memories prior to the trauma are still intact (Loss of STM). END.
           There are a number of other specialised types of memory that can be used to store information, depending on the task. Declarative memory sometimes referred to as explicit memory is one of two types of long term memory and refers to memories that can be recalled such as facts and knowledge, this refers to material that is consciously learnt and retrieved. This type can further be divided into episodic memory which is used to store personal experiences such as a memory from your favourite holiday and semantic memory which stores factual information (such as naming the capital cities of the world). The other type of LTM is procedural memory, often referred to as implicit, because the memory process for learning and recalling such memories is unconscious. This includes memories that are used to perform skills, for example how to drive a car. These sorts of memories are concerned with the ability to perform motor functions in a certain order, these types of memories are called 'proceduralized'.
Working memory actively holds information in the mind in order to perform further processing. For example reading a sentence and then processing the words so you can understand it.
Lateralization of memory
Encoding and retrieval of episodic and semantic memory has been associated with activation in the pre frontal and medial temporal cortex. Activation may be left-sided if the episodic material is verbal, bilateral if non-verbal. Working memory selectively activates the pre frontal cortex.
A model called the HERA model has been proposed to account for the differences in activation seen during memory encoding and retrieval. HERA stands for hemispheric encoding-retrieval asymmetry. This model argues that the left hemisphere is more active during episodic encoding, whereas greater activation in the right frontal cortex is seen during episodic retrieval.

Frontal Lobes

The frontal lobe is an area of the brain that can be seen in both humans and other mammals. It is positioned at the front of the cerebral hemispheres and is thought to be the most complex lobe of the brain. This is because it is responsible for a number of higher brain functions, including mediating abstract thought, as well a planning and organising behaviour and emotions. It is also involved in memory, creativity, intelligence and language among other functions.
Over the last 150 years there have been a large number of case studies of patients with damage to the frontal lobes. The most well known is an individual called Phineas Gage who suffered a severe accident, in which an iron rod was blown through his head during a construction accident. This caused severe damage to the frontal lobes and severely altered aspects of his personality. Later case studies showed that damage to the frontal cortex was associated with impaired cognitive and intellectual functioning. Although observable effects from brain damaged individuals have been a useful tool into mapping the frontal lobes, there are a number of tests that have been designed to measure frontal lobe function.
The most commonly used test to measure frontal lobe function is the Controlled Oral Word Association test which was formulated to measure verbal fluency and involves asking the patient to name as many words as possible beginning with the same letter. Those with frontal lobe damage often perform much poorly than controls. The Wisconsin card sorting test is another well known test used to analyse frontal lobe functioning. This involves the subject sorting cards in to piles, using different rules for example by shape colour or number, without warning the experimenter changes the sorting principle. It is commonly found that those with frontal lobe damage take much longer to adjust to the new principle ( this is called perseveraton), compared to normal controls.
The symptoms caused by brain injury to the frontal lobes can be quite vast but most commonly it reduces a persona ability to plan and organise, effecting both planning ahead and voluntary motor behaviour. An individuals perception of smell and taste can also be altered when the frontal lobes are damaged. t is also found that damage to the frontal lobes causes individuals to become lethargic and speak very little, often doing poorly on verbal tests.

Hemispheric Lateralisation

The human brain is split into two cerebral hemispheres, connected by the corpus callosum. Broad generalisations are often made about each hemisphere having characteristic labels. The left side is often thought to deal with language production and comprehension and generally be more rational and analytic. The right hemisphere on the other hand is often labelled as creative, emotional and intuitive. Underlying these labels is the idea that each hemisphere is thought to be qualitatively and quantitatively different, with one hemisphere being more dominant in a particular characteristic than the other hemisphere. This is supported by evidence from a number of different studies involving research on language, visuo spatial abilities, and split brain patients. Split brain patients are people who have under gone a particular type of surgery in order to try and rid epileptic seizures. The surgery involves severing the corpus callosum in order to destroy the path of the epileptic seizure. The result of this surgery is that the two hemispheres are unable to interact because all connections have been broken and therefore the two hemispheres act as two separate brains. This finding suggests that the two hemispheres are independent of one another.
The research on language has most commonly been tested by using neuroimaging techniques such as Functional Magnetic Resonance Imaging (fMRI) scans which measure the flow of blood within the brain, the faster the flow of blood, the more oxygen that is being used and therefore the more energy the brain is using. This scan helps us to see which areas of the brain are active when different tasks are completed and thus helps us to localise brain function. When studying language participants are given tasks such as recognising words or may be asked to speak or read a few sentences, therefore allowing us to see where these functions take place, in most patients language tasks are found to activate areas within the left hemisphere. Occasionally some people are found to have activation in the right hemisphere but this is much rarer .

Emotion

Emotions are often produced by stimuli that have high significance to the individual, and thus give rise to high bodily arousal, arousal meaning physiological response, often those related to fight or flight reactions.
There is controversy about whether it is the emotion (sadness) that elicits the physiological response
(eg crying), or the physiological response that elicits the emotion.


There have been a few different theories of emotion
Common Sense theory: Claims that the individual will first experience the stimulus (for example- See a bear), the perception will then occur (interpretation of stimulus -Danger), which will lead to an emotional state and this will cause the bodily arousal (pounding heart).
James Lang theory: Claims that it is the other way round and that the stimulus is followed by the perception of the stimulus, followed by bodily arousal and this leads to the emotional state (fear).
Cannon Bard theory: Claims that after the perception of stimulus, both the bodily arousal and the emotion will occur at the same time.
Schachter Cognition plus Feedback theory claims that the same physiological arousal accompanies all emotions but it is our own interpretation of the physiological arousal, that defines the emotion we feel. This is because emotions are subjective to the individual, happy sad angry all mean different things to each one of us but it is how we label our feelings which is important.
In order to understand how we process emotion it is important to look at the brain in more detail. It has been found that there are specific areas within the brain that have a role in emotion.
The amygdala is a collection of nuclei in the anterior temporal lobe and has been found to be heavily involved in emotion. In 1998 Le Doux called the amygdala the 'emotional brain'. There are several factors factors that provide evidence for the role of the amygdala in emotion. Firstly case studies with humans who have damage to the amygdala. It has been found that post  injury, humans have a reduced number of emotional behaviours and often exhibit a change in personality traits, such as being more aggressive and grumpy, suggesting an alteration in there emotional state. Secondly researchers have created experimental lesions in different species of animal and noted the behavioural changes both before and after surgery. Research with psychopaths has also found that damage to the amygdala has effected their ability to read facial expressions and thus there ability to understand emotion. This may account for their lack of empathy with there victims, since they do not understand what pain or fear look like. The amygdala has also been implicated in fear conditioning, it has been found that when pathways to the amygdala are damaged the animal subject can not learn fear conditioning, therefore reinforcing the role of the amygdala.
It has been found that the right hemisphere of the brain is more involved in emotional perception, particularly the orbito-frontal cortex. The majority of evidence again comes from human case studies of brain lesioned individuals. However both hemispheres have been found to be involved in emotional expression.