The Four Lobes Occipital Lobe Structure The two

The Four Lobes

Occipital Lobe Structure • • • The two occipital lobes (Left & Right) are the smallest lobe in the human brain. Located in the rearmost portion of the skull. They are structurally isolated in their respective cerebral hemispheres by the separation of the cerebral fissure. At the front edge of the occipital lobe are several occipital gyri, which are separated by lateral occipital sulcus. The occipital aspects along the inside face of each hemisphere are divided by the calcarine sulcus. Above the medial, Y-shaped sulcus lies the cuneus, and the area below the sulcus is the lingual gyrus. Damage to the primary visual areas of the occipital lobe can cause partial or complete blindness.

Occipital Lobe Functions • Vision • Recognition of Visual Objects • • • The first functional area is the primary visual cortex. It projects to the occipital areas of the ventral stream the dorsal stream. The ventral stream is known for the processing the "what" in vision, ventral stream provides important information for the identification of stimuli that are stored in memory. while the dorsal stream handles the "where/how. " the dorsal stream is able to focus on motor actions in response to the outside stimuli.

Temporal Lobe Structure • The temporal lobe consists of structures that are vital for declarative or long-term memory. • Declarative or explicit memory is conscious memory divided into semantic memory (facts) and episodic memory (events). • Medial temporal lobe structures that are critical for long-term memory include the hippocampus, along with the surrounding hippocampal region consisting of the perirhinal, parahippocampal, and entorhinal neocortical regions. • Other structures include Heschl’s Gyrus, Superior Temporal Gyrus, Middle Temporal Gyrus, & Inferior Temporal Gyrus • Left & Right temporal lobes are connected by the corpus callosum

Temporal Lobe Functions Left Temporal Lobe • • • Ability to combine input into patterns Ability to perceive two objects or two attributes of a single object at the same time Ability to read or recognize numbers, or visually process symbolic stimuli Ability to remember verbal material presented visually Ability to name colours Perception of acoustic intensity Integration of auditory & visual information Memory functions for verbal stimuli Comprehension of visual-verbal symbolic Using words to name objects Ability to discriminate between different sounds Right Temporal Lobe • • • Recognition of objects from incomplete picture Ability to recognize anomalies in picture Identification of meaningless visual patterns Visuo-spatial abstract reasoning Recognition of rhythmic patterns – pitch & rhythm Discrimination of tonal patterns & familiar melodies Ability to localize oneself in space by means of visual cues Ability to recognize faces Ability to perceive spatial relations Auditory perception, Emotional Stability, Orientation in time & Space, Ability to form new memories, Ability to recognize olfactory stimuli

Parietal Lobe Structure • The parietal lobe is defined by three anatomical boundaries: The central sulcus separates the parietal lobe from the frontal lobe; the parieto-occipital sulcus separates the parietal and occipital lobes; the lateral sulcus (sylvian fissure) separates it from the temporal lobe; and the longitudinal fissure divides the two hemispheres. • Within each hemisphere, the somatosensory cortex represents the skin area on the contralateral surface of the body. • The most anterior part of the parietal lobe, is the postcentral gyrus, the primary somatosensory cortical area. Separating this from the posterior parietal cortex is the postcentral sulcus. • The posterior parietal cortex can be subdivided into the superior parietal lobule and the inferior parietal lobule, separated by the intraparietal sulcus (IPS). • The intraparietal sulcus and adjacent gyri are essential in guidance of limb and eye movement.

Parietal Lobe Functions Left Parietal Lobe • • Ability to process symbolic stimuli (languages) – comprehend written material, & understand spoken language Ability to produce writing Ability to correctly manipulate numerical symbols due to recognition of the value of a number Ability to execute or recall a purposeful activity upon command. Logical flow & integrated sequence of intentional movement Ability discriminate left from right (parieto -occipital function) Ability to localize and correctly name parts of the body Correctly localize or discriminate fingers Right Parietal Lobe • • • Ability to construct or assemble objects from their component parts Body-spatial awareness (kinesthetic awareness) Visuo-spatial ability General: Recognition of objects or symbols in a sensory modality, recognition of objects by touch alone, ability to synthesize separate tactile sensations into the perception of form

Frontal Lobe Structure • The frontal lobe is the largest lobe of the brain and makes up about a third of the surface area of each hemisphere. On the lateral surface of each hemisphere, the central sulcus separates the frontal lobe from the parietal lobe. The lateral sulcus separates the frontal lobe from the temporal lobe. • Some of the areas include: primary motor cortex, premotor cortex, Broca’s area, medial cortex & prefrontal cortex

Frontal Lobe Functions Left Frontal Lobe • • • Expressive speech Control of speech apparatus Regulation of role of speech Verbal memory Consciousness, emotionality & attention Pre-motor Area • Integration and refinement of complex motor tasks • Voluntary movement • Kinetic rhythm Right Frontal Lobe • • • Ability to understand proverb Ability to construct complex objects Visual-spatial integrations Ability to sing Ability to control motor movement on left side of the body Nonverbal visual memory

Prefrontal region Functions • Cognitive & behavioural flexibility & ability to shift between sets • Regulate rate of behaviour & ability to be spontaneous • Ability to start behaviour • Ability to terminate behaviour • Ability to regulate attention • Abstract thinking • Self-awareness & responsiveness to social feedback