Brain Function

A Big Man Sings Very Well Auditory, Broca's, Motor, Somatosensory, Visual and Wernicke's

remember the key functional areas of the cerebral cortex in a clockwise direction when looking at the left hemisphere of the brain: acronym

cerebral cortex is a thin layer of cells, only 2-3mm thick (cortex means "bark" or thin covering) that covers the outer portion of the brain. here are three main functional components to the cerebral cortex: *Sensory Areas *Motor Areas *Association Areas

Cerebral Cortex

are remaining areas located in each of the four lobes. The association areas integrate information from the sensory and motor areas and are primarily in involved in higher mental brain functions like decision making, planning, and so on.

Cerebral Cortex- Association Areas

Motor Areas: there is only one primary motor cortex located in the frontal lobe which sends information about the voluntary movement of various bodily muscles.

Cerebral Cortex- Motor Areas

receives and integrates sensory information provided by the various senses (taste, smell, touch, vision, and hearing).

Cerebral Cortex-Sensory Areas

located at the base of the brain. second largest part of the brain that is responsible for coordinating fine muscle movements and regulating posture and balance. The cerebellum is also involved in learning and memory associated with movement in particular.

Cerebellum

People who have damage to the cerebellum have difficulty walking, keeping their balance, and holding their hands steady.

Damaged Cerebelum

The job of the reticular formation is to filter out some of the stimuli that are coming into the brain from the spinal cord. The reticular formation regulates arousal, influencing whether we are awake or asleep.

Reticular Formation

When electrical stimulation is applied to the reticular formation of an animal, it immediately becomes fully awake, and when the reticular formation is severed from the higher brain regions, the animal falls into a deep coma.

Electrically stimulating the reticular formation

The forebrain is the largest and most prominent part of the brain. Its major structures include the thalamus, hypothalamus, and cerebrum. The forebrain regulates complex cognitive processes such as thinking, learning, memory and perception, as well as various aspects of emotion and personality.

Forebrain

Cerebellum. Consuming alcohol influences the cerebellum, which is why people who are drunk have more difficulty walking in a straight line.

Alcohol affects the . . .

The cerebrum, occupies most of the forebrain, is primarily responsible for almost everything we consciously think, feel and do. The cerebrum (including the cerebral cortex) is divided into two cerebral hemispheres connected by the corpus callosum. Each hemisphere can be further subdivided into four lobes (discussed in next topic).

Cerebrum

The frontal lobe is the largest of the four lobes and occupies the upper forward half of each cerebral hemisphere. It is right behind your forehead. The frontal lobe is primarily responsible for three major functions: • Association areas - higher mental functioning • Primary motor cortex - controls voluntary movement • Broca's area (located in the left frontal lobe) - speech production

Frontal Lobe

• are involved in higher mental functions, including thinking, organising and planning, abstract reasoning, judging/deciding, problem solving, using initiative and carrying out sequences of behaviour. People with damage to the frontal lobe have difficulty paying attention to their surroundings, coordinating complex sequences of behaviour, as well as difficulty with making and carrying out plans. • Association areas are also associated with the expression of emotional behaviour and with certain personality characteristics, especially those that relate to temperament. People with damage to the frontal lobe also have difficulty displaying appropriate emotional responses in social situations (e.g. Phineas Gage).

Frontal Lobe- Association Areas

• Broca's area is located within the frontal lobe, immediately below and in front of the motor cortex (areas that control the muscles of the face, tongue, jaw and throat). It is located in the left hemisphere (in ninety-five per cent of right-handers and seventy per cent of left-handers) • Broca's area is thought to be responsible for the production of articulate (clear and fluent) speech; more specifically, the motor coordination (working together) of the physical components of speech (lips, tongue, mouth, etc.). It is sometimes referred to as the 'speech production centre'. • Broca's area is also concerned with the grammatical structure of sentences, and with parts of speech such as adjectives, prepositions and conjunctions. • Damage to Broca's area causes Broca's aphasia - an inability to produce fluent speech but without disruption to comprehension of spoken or written language. The speech of patients who have suffered damage to Broca's area typically comprises short sentences of just three or four words that consist mainly of nouns and verbs; for example, "Got phone, spoke friend".

Frontal Lobe- Broca's Area

• Is located at the very rear of the frontal lobe and its function is to direct and control voluntary movements of skeletal muscles. • Various locations on the motor cortex are responsible for generating movement of certain parts of the body. For example, the motor cortex in the left frontal lobe controls voluntary movements on the right side of body and vice versa; areas at the top of the motor cortex control lower parts of the body and vice versa • The amount of motor cortex devoted to a body part is related to the precision of movement, not to the size of the body part - hands, fingers, mouth and lips have proportionately larger areas of motor cortex; this enables precise control of our fingers, mouth, lips, etc.

Frontal Lobe-Primary Motor Cortex

The hindbrain is the lowest portion of the brain and consists of the medulla and the cerebellum.

Hindbrain

The forebrain structure that regulates behaviours associated with basic biological needs, such as eating, drinking, and sex is called the hypothalamus. Damage to the hypothalamus could result in an overwhelming urge to eat or the degeneration of sex organs and a significant reduction in sex drive (in males only). In a famous experiment, the hypothalamus of a rat was removed. It was found that the removal of the hypothalamus caused the rat to constantly eat until it was twice its normal weight.

Hypothalamus

The left hemisphere predominately controls verbal and analytical functions. • Verbal functions involve the use of language-based abilities - for example reading, writing, speaking and language comprehension (understanding speech). • Analytical functions are mental abilities involving logical reasoning, analysing, organising and interpreting data - for example the use of mathematical logic, interpreting scientific data and evaluating an experimental design in Psychology. • The left hemisphere also receives somatosensory information from the right side of the body and controls voluntary muscle movement in the right side of the body

Left Hemisphere

The medulla controls vital bodily functions such as breathing, heart rate, blood pressure, etc..., all of which occur automatically and are essential for survival.

Medulla Oblongata

The midbrain is an area where many nerve-fibers ascend and descend and relay information between the brain and the hindbrain.

Midbrain

The occipital lobe occupies the very back of the cortex of each cerebral hemisphere and is the smallest of the four lobes. The occipital lobe's primary function is the processing of visual information. The occipital lobe is primarily responsible for two major functions: • Association areas: bring together visual information and information from other lobes • Primary visual cortex: where the information from the two eyes is received and processed

Occipital Lobe

• select and organise visual information, enabling us to form meaningful visual perceptions. • integrate features of the visual stimulus with other information from other areas of the cerebral cortex, enabling us to think visually, and to remember visual images. The visual association areas extend beyond the occipital lobes into the temporal and parietal lobes. • People with damage to the occipital lobe may experience blind spots in their vision or may not be able to recognise the whole object, person or colour (despite being able to describe parts of the visual stimulus

Occipital Lobe- Association Areas

• The primary visual cortex receives and is responsible for the initial processing of visual information, that is, it is where signals from the retina are formed into visual sensations such as lines, lights/shadows, colours and textures. In turn, these are transformed into meaningful visual perceptions in the association areas of the occipital lobe • the right occipital lobe processes left visual field (not the left eye; inputs from right half of each eye) whereas, the left occipital lobe processes right visual field (not the right eye; inputs from the left half of each eye)

Occipital Lobe- Primary Visual Cortex

The parietal lobe occupies the upper back half of the brain of each cerebral hemisphere. It is located behind the frontal lobes and just above the occipital lobes. The parietal lobe is primarily responsible for two major functions: • Association areas: processes somatosensory information (monitoring the body's position in space) and integrating visual information (attending to and perceiving objects) • Primary somatosensory cortex: receives and processes sensory information from sensory receptors in the skin responsible for touch, temperature, pressure, pain and body movements

Parietal Lobe

• processes sensory information felt by your body as it moves - this enables us to monitor our body's limb position in space. • integrate visual information, including visual attention and spatial reasoning - this enables us to determine the spatial positions of objects; that is, where they are located in the environment. • Damage to the right parietal lobe can cause spatial neglect, which is the continual failure to notice anything on the left side of body. Patients with spatial neglect (damaged right parietal lobe) the left side of their body and the space around it. For example, people may only shave the right side of their face or dress only the right side of their body.

Parietal Lobe- Association Areas

• located in the parietal lobes / parallel to the primary motor cortex. • It receives and processes sensory information from the sensory receptors in the skin. This sensory information includes touch, pressure, pain, temperature, muscle movement and position. • Various locations on the somatosensory cortex receive sensations of touch from specific body parts, e.g. the sensory cortex in the left parietal lobe receives and processes sensory information from the right side of body and vice versa; areas at the top of the sensory cortex receive inputs from lower parts of the body and vice versa • The amount of somatosensory devoted to a body part is related to the sensitivity of that body area, not to the size of the body part. For example, the fingers, mouth and lips have proportionally more sensory cortex, suggesting that they are sensitive to touch.

Parietal Lobe-Somatosensory Cortex

The right hemisphere predominately specialises in non-verbal functions. • Non-verbal functions are those that do not require the use or recognition of language. Non-verbal functions include: spatial and visual thinking (e.g. reading maps) recognising faces, objects, patterns, tunes, emotional expression and facial cues musical and artwork appreciation (but not necessarily producing them) fantasy (for example, daydreaming) / creativity • The right hemisphere also receives somatosensory information from the left side of the body and controls voluntary muscle movements in the left side of the body.

Right Hemisphere

Temporal Lobe The temporal lobe is located on each side of the brain and is located in front of the occipital lobes, but below the frontal and parietal lobes. The temporal lobe is primarily responsible for three major functions: • Association areas: these have been implicated in several functions, including memory, object identification and face recognition • Primary auditory cortex: receives and processes sounds of different frequencies from both ears • Wernicke's area: involved with the comprehension of speech

Temporal Lobe

• involved in memory formation, for example, people who have experienced amnesia (partial or complete loss of memory) are often found to have damaged their temporal lobe. Furthermore, people who suffer from Alzheimer's Disease (which causes a loss of memory) have been found to have significant cortical shrinkage and decay of the temporal lobe. • involved in object identification (i.e. what an object is) • involved in the recognition of faces (being able to recognise a person as someone you know). People who suffer damage to the temporal lobes may be unable to recognise the face of someone they know (facial agnosia), even if it is a picture of themselves (although they are able to describe facial features and identify the sex and approximate age of that person).

Temporal Lobe- Association Area

• receives auditory information from the ears, such as the frequency (pitch) and amplitude (loudness) of the noise, and processes them into meaningful sound sensations (words or music) • although both sides receive information from each ear, the left temporal lobe receives information from the right ear slightly before the right temporal lobe does and vice versa • each auditory cortex is specialised to process different types of sounds - the left temporal lobe mainly processes verbal sounds (e.g. words), whereas the right temporal lobe mainly processes non-verbal sounds (e.g. music)

Temporal Lobe-Primary Auditory Cortex

• is usually located in the left hemisphere (in ninety-five per cent of all people) • is sometimes referred to as the 'language comprehension centre', as it is the area involved in the comprehension of speech. That is, it is responsible for understanding spoken/written words and is concerned with putting them into meaningful sentences. • It contains our semantic (word meaning) analyser and is responsible for locating and retrieving words from memory to express intended meanings when we speak or write. • Damage to Wernicke's area causes Wernicke's aphasia - an inability to comprehend meanings of spoken words or language. Speech production or fluency of speech is not disrupted; however, the person's speech is meaningless, that is, they can string together long word sequences and phrases but not in an understandable way (speak nonsense)

Temporal Lobe-Wernicke's area

is mainly as a relay station. The thalamus applies more filtering to the sensory information that is coming through the reticular formation, and it relays these remaining signals to the cerebral cortex. The thalamus is also important in sleep because it shuts off incoming signals from the senses, allowing us to rest.

Thalamus