Human Neuropsychology Exam 2.5

Where is the Temporal lobe?

The cortex below the sylvian fissure and is anterior to the occipital and parietal lobes

• Boundary is the occipital notch

Two structures of the inferior parietal lobe that form temporal boundary

Angular gyrus and Supramarginal gyrus

Superior temporal sulcus

Separates superior and middle gyri

Sylvian fissure

Forms dorsal boundary, covers the insular cortex

Collateral sulcus

Separates parahippocampal gyrus from fusiform gyrus

Inferior surface of temporal lobe

• Fusiform gyrus

• Parahippocampal gyrus

• Uncus

Medial features of temporal lobe

• Hippocampal complex

  • Uncus

  • Entorhinal cortex

  • Perirhinal cortex

  • Dentate gyrus

Temporal lobe’s other features

• Heschl’s gyrus

• Insular cortex

• Amygdala

• Planum temporale

#1?

Short association fibers

#2?

Superior longitudinal fasciculus

#3?

Short gyri of the insula

#4?

Inferior occipitofrontal fasciculus

#5?

Central sulcus of the insula

#6?

Limen insulae

#7?

Longitudinal gyrus of the insula

#8?

Inferior longitudinal fasciculus

Parahippocampal gyrus

Flow of information for the hippocampal complex begins here; this contains the perirhinal cortex, entorhinal cortex, and parahippocampal cortex

Purple?

Amygdala

Yellow?

Perirhinal cortex

Red?

Entorhinal cortex

Green?

Hippocampus

Light green?

Parahippocampal cortex

Perirhinal cortex

Area of the brain at the boundary of the medial temporal lobes and ventral visual pathway, part of the hippocampal complex

• Receives sensory input from all sensory regions

• Important for familiarity and recency discrimination

• Processes information about novelty

• Important for object recognition

Entorhinal cortex

Part of the hippocampal complex important for;

• Declaritive memory (Autobiographical, episodic, and semantic)

• Spatial memory and navigation

• Consolidation of memory

This area is affected early in Alzheimers

Parahippocampal cortex

Part of the hippocampal complex, important for;

• Visuospatial processing

• Topographical and autobiographical memory

• Contexual associations

• Episodic memory

• Contextual processes

• Navigation

• Scene processing

Function of blue area

Spatial information in the parahippocampal gyrus

Blue?

Parahippocampal gyrus

Function of green area?

Object information in the perirhinal cortex

Green?

Perirhinal cortex

Function of yellow area?

Binding of information in entorhinal cortex

Yellow?

Entorhinal cortex

Pink?

Hippocampus

Red?

Mammillary body

Hippocampus sends info to the mammillary body through what structure?

Fornix

Mammillary body sends info where?

Anterior thalamus

Opercula

The parts of the frontal, parietal, and temporal lobes that fold over and cover the insular cortex, located deep within the brain's lateral sulcus

Subiculum

Lies between the entorhinal cortex and the hippocampus proper

Is the primary output for hippocampus

Hippocampus proper

Main function is consolidation from short-term to long-term, episodic and autobiographical memory

Explicit memory

Dentate gyrus

Receives fibers from entorhinal cortex, this is the first step in processing of information that leads to episodic memory formation

Afferent connections of temporal lobe

The sensory systems

Efferent connections of temporal lobe

Parietal and frontal areas

Limbic system

Basal ganglia

MOTOR

Ventral stream

The “what” system

Primary auditory projection

Heschl’s gyrus (Dorsal portion of superior temporal gyrus)

• Near the insular region

• Within the Sylvian fissure

Projections arise from cochlea sense receptors

• Info from one ear goes tp both temporal lobes

• Receives mostly contralateral input

Damage to the Primary auditory projection

Peripheral receptors- Deafness on same side

Primary auditory cortex- Partial deafness

Auditory cortex- Impaired sound localization and problems with bilateral hearing

Complete cortical deafness

Requires bliateral damage and is very rare

Primary auditory cortex organization

Tonotopic columnar

• High frquency to medial

• Low frequency to lateral

Auditory association areas

• Speech sounds, quick speech, and verbal info to left

  • Comprehension of speech

• Perception of nonverbal information, melody, prosody, tempo, and rhythm

Primary Gustatory cortex

Two main projections:

• Frontoparietal operculum

• Anterior insular cortex

Primary Olfactory cortex

Located on anterior tip of the temporal lobe (Near olfactory bulbs)

• Only system where fibers reach cortex without passing through thalamus

Primary Vestibular cortex

Posterior insular cortex

Stimulation of Vestibular cortex

Results in spinning on opposite side

• Stimulate left = rotate to right

• Stimulate right = rotate to left

Ablation of Vestibular cortex

• Lesion on left = rotate to left

• Lesion on right = rotate to right

Lesions may disrupt perceptual judgement about body orientation

Visceral functions of temporal lobe

Yields changes in heart rate and blood pressure, this involves insular cortex

• Stimulate left Insular cortex = decrease in HR and BP

• Stimulate right insular cortex = increase in HR and BP

• Lesion left insular cortex = increase in HR and BP

• Lesion right insular cortex = decrease in HR and BP

Visceral functions of temporal lobe by hemisphere

• Left is parasympathetic (Rest and digest)

• Right is sympathetic (Fight or flight)

Neuroimmunological functions of temporal lobe

Left insular cortex associated with immunoexcitation

Right insular cortex associated with immunosuppression

Visual perception functions of temporal lobe

Integrates visual experience with other sensory experiences

• Optic radiations pass through temporal lobes

• Temporal lesions can result in visual field deficits

Temporal lobe lesions to auditory perception, left side

• Impairment of conscious sensation

• Bilateral damage not necessarily associated with cortical deafness

• Difficultly discriminating different frequency or judging the timing of sounds

• Difficulty judging temporal order in which sounds are heard

• Rhythm

  • Mostly from superior temporal gyrus lesions

Right side effects of temporal lobe lesions

Difficulty perceiving loudness, quality, and pitch

Prosody, timbre, and melody are affected too

Wernicke’s aphasia

Left superior temporal lesion

• Secondary association cortex is planum temporale

• Speech comprehension is affected

• Still fluent

• No motor

Receptive aprosodia

Right superior temporal lesion

• Comprehension is intact, excpet for nonpropositional speech

• Cannot hear the emotion/prosody

Prosopagnosia

Related to the fusiform gyrus

The inability to recognize familiar faces

Apple tree analogy for Alzheimer’s Disease

Their baskety has holes, any apple that is held will fall out walking to the cellar

AKA the problem is encoding and consolidation

Inferotemporal damage and memory

Interferes with conscious recall of memory

Alzheimer’s Disease affects what types of memory

• Episodic

• Semantic

• Working

Other affects of Alzheimer’s Disease

• Language

• Visual-spatial processing

• Executive

Symptoms of AD

• Forgetfulness

• Getting lost

• Repeating self

• Planning and problem solving difficulty

• Confusion

• Judgement

Typical progression of AD

• Basal to dorsal

• Olfactory bulbs first

• Then medial temporal

• Then frontal and parietal

• Left side is usually more effected

Beta-amyloid

The protein that forms plaques in AD, these plaques disrupt intraneuronal neuronal communication

Tau proteins

Constituents of the neurofibrillary tangles

• Interneuronal abnormality

• Microtubule associated protein

• Becomes hyperphosphorylated

• Cell functions not supported

• Neuronal death

Acetylcholine 

Loss of cholinergic neurons in AD

Left temporal memory

Verbal, not debated

Right temporal memory

Visuospatial memory, heavily debated

Kluver-Bucy Syndrome

Five categories of behavioral changes after bilateral temporal lobectomy

• Decreased fear

• Psychic blindness

• Oral tendencies

• Increased exploration

• Sexual behavior changes

Amygdala damage

Flattened emotional expression and decreased aggression

Amygdala stimulation

Agression, anxiety, fear and sense of danger

Teal?

Superior temporal gyrus

Red?

Middle temporal gyrus

Green?

Inferior temporal gyrus

Purple?

Temporal pole

Yellow?

Rhinal cortex

Pink?

Fusiform gyrus

Blue?

Parahippocampal gyrus

Green?

Cingulate cortex

Red?

Insula

Blue?

Amygdala

Green?

Planum temporale

Blue?

Heschl’s gyrus

Yellow?

Supramarginal gyrus

Orange?

Angular gyrus

Green?

Wernicke’s area

Pink?

Primary auditory area