The temporal lobe plays important roles in processing sensory input such as auditory and visual information. It is involved in functions such as memory formation, emotion processing, and language comprehension. Damage to temporal lobe structures can cause symptoms like auditory or visual processing issues, memory impairments, and changes in emotional behavior or personality. The superior, middle, and inferior temporal gyri and medial temporal structures each contribute to these various temporal lobe functions.

1. TEMPORAL LOBE ANATOMY,
FUNCTION & EVALUATION
DR. PIYUSH OJHA
DM RESIDENT
DEPARTMENT OF NEUROLOGY
GOVT MEDICAL COLLEGE, KOTA

2. ANATOMY
• Percentage of Temporal lobe:total cerebral cortex volume in humans: 22%
• The Temporal Lobe contains all the tissue in the brain that lies below the
Sylvian (Lateral) fissure and anterior to the Occipital cortex.
• Subcortical Temporal lobe structures include –
- Limbic cortex
- Amygdala
- and Hippocampal formation.
• Connections to and fro from the temporal lobe extends throughout the
brain.
• Has 2 sulci that run parallel to the posterior ramus of the lateral sulcus
named Superior and Inferior temporal sulci.
• These sulci divide the superolateral surface of temporal lobe into Superior,
Middle and Inferior Temporal Gyri.

3. • Temporal lobe includes-
1. superior, middle & inferior temporal convolutions
2. lateral occipitotemporal convolutions
3. fusiform convolutions
4. lingual convolutions
5. parahippocampal and hippocampal convolutions
6. Transverse gyri of Heschl (PRIMARY AUDITORY RECEPTIVE AREA)

4. • Brodmanm areas on lateral suraface
of Temporal lobe –
- Auditory area (area 41, 42)
- Auditory association cortex (area 22)
- Ventral visual stream areas
( area 20, 21, 37 & 38 )

5. The Medial Temporal region (LIMBIC CORTEX) includes :-
- Amygdala and adjacent cortex (Uncus )
- Hippocampus and the surrounding cortex i.e.
- Subiculum
- Entorhinal Cortex (Brodmann area 28 )
- Perirhinal Cortex (Broadmann area 35 & 36 )

6. BLOOD SUPPLY OF TEMPORAL LOBE
• Convexity – inferior branch of MCA
• Medial & inferior aspects (including Hippocampus) – temporal
branch of PCA

7. SUPERIOR TEMPORAL LOBE
• This is bounded by:
- the lateral sulcus above;
- the superior temporal sulcus below;
• It contains several important structures including:
- Brodmann areas 41 and 42, marking the location of the Primary auditory
cortex, known as Transverse temporal gyri (also called Heschl's gyri)
- Wernicke's area, Brodmann 22

8. MIDDLE TEMPORAL LOBE
The region encompasses most of the lateral temporal cortex, a region believed to
play a part in auditory processing and language.
- Language function is left lateralized in most individuals.
- Brodmann area 21.

9. INFERIOR TEMPORAL LOBE
• In humans it corresponds approximately to the inferior temporal
gyrus.
• Brodmann area 20.
• The region encompasses most of the ventral temporal cortex, a
region believed to play a part in high-level visual processing and
recognition memory.

10. AMYGDALA
•The amygdala (Latin,meaning
'almond') are almond-shaped
groups of neurons located
deep within the medial
temporal lobes of the brain, in
close relation to anterior end
of inferior horn of lateral
ventricle, located at anterior
end of hippocampal formation.

11. The Hippocampus
- The hippocampus is a scrolled structure
located in the medial temporal lobe.
- can be divided into at least 5 different areas.
- Areas CA3 and CA1 are more diffuse; CA2 is
hard to distinguish between them.
- (CA stands for cornu ammonis, from its
ram's horn shape.)
- The subiculum sits at the base of the
hippocampus, and is continuous with
entorhinal cortex, which is part of the
parahippocampal gyrus.

12. Dentate gyrus
• Part of the hippocampal formation.
• Contains granule cells, which project to the pyramidal cells
and interneurons of the CA3 subfield of the hippocampus.
• The granule cells are the principal excitatory neurons of the
dentate gyrus.
• The major input to the dentate gyrus (Perforant pathway) is
from the entorhinal cortex, and the dentate gyrus receives no
direct inputs from other cortical structures.
• The dentate gyrus is also one of the few regions of the brain
where neurogenesis takes place. Neurogenesis is thought to
play a role in the formation of new memories.

13. Connections of the Temporal Lobes-
Five main types:
1. Hierarchical sensory pathway
2. Dorsal auditory pathway
3. Polymodal pathway
4. Medial (mesial) temporal pathway
5. Frontal lobe projection

14. Hierarchical sensory pathway
connections from primary and secondary auditory
and visual cortical
through the lateral temporal cortex
terminate in the temporal pole
• Subserves stimulus recognition

15. Dorsal auditory pathway
• Forms important functional connections from auditory areas
to posterior parietal cortex
• Concerned with directing movements with respect to
auditory information

16. Polymodal Pathway
• A series of parallel projections from the visual and auditory
association areas into the polymodal regions of the superior
temporal sulcus
• Functions in stimulus categorization

17. Medial Temporal Projection
• Projections from auditory and visual areas into the limbic
regions
E.g., amygdala and hippocampus
• Also called Perforant pathway
• Serves function in long term memory

18. Frontal-lobe Projection
• Auditory and visual information goes to two prefrontal
regions, one on the dorsolateral surface and the other in the
orbital region
• necessary for various aspects of movement control, short-
term memory and affect.

19. Temporal Lobe Function
• Three Basic Sensory Functions :
– Processing auditory input
– Visual object recognition
– Long-term storage of sensory input (Memory)

20. Temporal Lobe Function
• Sensory Processes
– Identification and Categorization of Stimuli
– Cross-Modal Matching
• Process of matching visual and auditory information
• Depends on cortex of the superior temporal sulcus
• Affective Responses
– Emotional response is associated with a particular stimulus
• Spatial Navigation
– Hippocampus – Spatial Memory

21. Superior Temporal Sulcus (STS) and
Biological Motion
• Functional Imaging reveals activation in the STS during perception of
Biological motion.
• Biological Motion
– Movements relevant to a species , Social perceptions
– Allow us to guess others’ intentions

22. FUNCTIONS OF TEMPORAL LOBE

23. Consider an example..
• Imagine that you want to buy a car and now you are riding a
two wheeler. On your ride, you notice many different cars,
and you decide to keep a mental list of the brands and colours
that you encounter so that you can discuss with family and
friends later on.
• As you ride along, you suddenly stop and back up—you have
encountered a traffic policeman on the roadside of the next
square walking with a fineslip towards you . You decide to
change routes and look for cars elsewhere!
• What temporal-lobe functions took part in your experience?

24. • To be aware of specific type, colour and brand- object
recognition by ventral visual pathway
• To categorize quickly as they are in motion-polymodal
pathway in superior temporal sulcus
• Matching acceleration/engine sound to visual input- Cross
modal matching by dorsal auditory pathway
• Policeman walking towards you- “Biological motion” by
superior temporal sulcus
• On seeing fineslip- increased HR and BP and affective
response- by amygdala
• To change route and search elsewhere (spatial orientation)-
hippocampus
• To remember all the cars and discuss- medial temporal lobe

25. TEMPORAL LOBE FUNCTIONS
• SPECIAL SENSES
– Hearing
• FUNCTIONS OF LIMBIC SYSTEM
– Memory
– Emotions & Mood
– Attitudes & Social Behaviour
• LANGUAGE FUNCTIONS
– Semantics
– Naming
• VISUAL & OTHER SENSORY INTEGRATION

26. HEARING
• Auditory cortex lies principally on the supratemporal plane of superior
temporal gyrus (Heschl’s gyrus)
• Primary cortex has tonotopic arrangement:
– high tones terminate in medial portion
– Low tones in lateral portions
• Particular sound frequency causes excitation of particular cortical area =
sound frequency perception
• Also helps in discrimination of sound patterns like combination or
sequence of tones
• Also takes part along with superior olivary nucleus in mechanism for
detecting sound direction

27. HEARING
Nondominant hemisphere- non-verbal aspect, recognition
of harmony & melody
Dominant hemisphere- verbal aspect,naming of musical
scores & all the semantic (writing, reading)
aspects of music

28. LIMBIC SYSTEM FUNCTION
• Coordinate sensory events with bodily and visceral needs
• Regulate innate automatised activities concerned with feeding,
searching, sex, & emotion-provoking situations
• Neurotransmitters:
– For memory- acetyl choline
– Norepinephrine in medial parts of limbic system
– Amygdala, septal nuclei & lateral parts are rich in serotonin

29. TEMPORAL LOBE/LIMBIC SYSTEM:FUNCTION
• Limbic system regulates emotions and motivations—
particularly those related to survival—such as fear, anger, and
pleasure (sex and eating)
• Feelings of pleasure/reward are very powerful and self-
sustaining. Pleasurable behaviors activate a circuit of
specialized nerve cells in the limbic area that is devoted to
producing and regulating pleasure called the reward system
29

30. Emotion and Motivation
(Individual function)
Rage, aggression Amygdala and hypothalamus.
Fear Amygdala and hypothalamus
Feeding Hypothalamus (satiety centers).
Sexual drive and behavior
Hypothalamus and limbic system
Goal directed behavior
(reward and punishment):
Hypothalamus and frontal cortex

31. MEMORY-
Medial temporal lobes
• The MTL is comprised of multiple structures
including the
• This is involved in explicit or declarative memory.
• It has essential role in the formation of new
memories about experienced events
(episodic or autobiographical memory).
Hippocampal formation,
Amygdala,
Entorhinal cortex, and
Surrounding perirhinal and parahippocampal cortices

32. Memory : HIPPOCAMPUS
• Critical in laying down declarative memory, but is not necessary
for working memory / procedural memory / memory storage.
• The hippocampal formation plays a role in memory
consolidation
• Damage to the hippocampus usually results in profound
difficulties in forming new memories (anterograde amnesia),
and normally also affects access to memories prior to the
damage (retrograde amnesia) but does not affect procedural
memory

33. Memory : Parahippocampal cortex
•Sensitive to familiarity with stimulus location or the geometry of
surrounding space
•Patients with a lesion limited to parahippocampal cortex lose
the ability to acquire new topographic knowledge
•The Parahippocampal Area responds selectively to visual
stimuli that convey information about the layout of local space.

34. Emotional learning
Amygdala perform primary roles in the formation and
storage of memories associated with emotional events

35. WERNICKE’S AREA
• The sensory area of the dominant hemisphere for interpretation
of language is Wernicke’s area.
• Closely associated with hearing areas
• Provides, at the input stage, an entry point for conversion of
auditory sequences into neural word representations leading to
meaning-appropriate content words.
• Localization of lexicon (vocabulary ) for spoken word recognition
exists in middle part of left superior & middle temporal gyri
• Lexicon for written word recognition exists in posterior part of left
middle temporal gyrus
• A major share of our sensory experience is converted into
language equivalent before stored in memory areas

36. WERNICKE’S AREA
Reception in primary auditory area
of sound signals that encode words
Interpretation of words in
Wernicke’s area
Determination of thoughts & words
to be spoken in Wernicke’s area
Transmission of signals form
wernicke’s area to Broca’s area by
arcuate fasciculus
Activation of skilled motor
programs in Broca’s area for control
of word formation
Transmission of appropriate signals
into motor cortex to control speech
muscles
Primary visual area is the
initial receptive area
Early stage of interpretation
in angular gyrus
Full level of recognition in
Wernicke’s area
Hearing & speaking Reading & speaking

37. VISUAL INTEGRATION
• Middle & inferior temporal gyri (areas 21 & 37) receive massive
contingent fibers form striate cortex (area 17) & parastriate visual
association areas (areas 18,19)
• Subserves visual discriminative functions like spatial orientation,
estimation of depth & distance, stereoscopic vision, & hue perception
• It integrates vision intimately with all forms of exteroception &
proprioception
• Bitemporal lobectomy in animals-‘psychic blindness’

38. SENSORY INTEGRATION
• Temporal lobe is great integrator of ‘sensations, emotions and
behaviour’
• It is the site where sensory modalities are integrated into ultimate
self-awareness
• Similar suprasensory integrative mechanisms are operative in
parietal lobe, but only in the temporal lobe are they brought into
close relationship to one’s instinctive & emotional life

39. • Stream of thinking (internal conversation that is constant in
waking state) requires language & memory functions, both of
which involve temporal lobe
• Temporal lobe throughout the life assembles all fragments of
present & past experiences of all kinds into awareness of
personal integrity which is only interrupted by sleep
• Temporal neocortex functions to bring ultimate awareness
that ‘I am’.

40. OTHER FUNCTIONS
• Vestibular functions:
– Some fibers from vestibular input are relayed in superior temporal
gyrus
– Episodic vertigo may represent the aura or sole manifestation of
temporal CPS
• Time perception:
– Main neural mechanism subserving time perception & integrating it
with other sensory inputs and memory lies in temporal lobe
– With disorder of temporal lobe of either side, there may be
intermittent disturbance of time perception

41. Symptoms of Temporal Lobe Lesions

42. Symptoms of Temporal Lobe Lesions
1. Disturbance of Auditory Sensation and perception
2. Disorders of music perception
3. Disorders of visual perception
4. Disturbance in the selection of visual and auditory input
5. Impaired organization and categorisation of sensory input
6. Inability to use contextual information
7. Impaired long term memory
8. Altered personality and affective behavior
9. Altered sexual behavior

43. Disturbance of Selection of Visual and
Auditory Input
• Selective attention to auditory input is impaired in patients
with temporal lobe damage and can be tested with dichotic
listening
• Damage to the left temporal lobe impairs recall of visual
stimuli in the right visual field
• Damage to the right temporal lobe impairs recall of visual
stimuli in both visual fields

44. Organization and Categorization
• Left temporal lobe lobectomies lead to impairment in the
ability to categorize words or pictures of objects
• Posterior lesions lead to a difficulty in recognizing specific
word categories

45. Using Contextual Information
• Stimuli can be interpreted in different ways depending on the
context
– Example: Fall - the season or a tumble

46. Memory
• Antereograde Amnesia
– Amnesia for events after bilateral removal of the medial
temporal lobes
• Inferotemporal Cortex
– Conscious recall of information
• Left temporal lobe
– Verbal memory
• Right temporal lobe
– Impaired recall of nonverbal material

47. Affect and Personality
• Stimulation of anterior and medial temporal cortex produces feelings of
fear
• Temporal lobe personality
– Personality that overemphasizes trivial and petty details of life
– Pedantic speech (an overly formal speaking style inappropriate to the
conversational setting)
– Egocentricity (preoccupation with one’s own internal world)
– Perseveration
– Paranoia
– Preoccupation with religion
– Proneness to aggression

48. Changes in Sexual Behavior
• Release of sexual behavior seen after bilateral temporal
damage

49. Superior temporal Gyrus
• Auditory radiations run from the medial geniculate body to the Auditory
cortex ( areas 41 and 42) in the superior temporal gyrus.
• Hearing is represented bilaterally in the temporal lobes.
(contralateral predominance)
• Nearby areas - differentiation and interpretation of sounds.
• Electrical stimulaton of auditory area leads to vague auditory hallucination
(tinnitus, sensation of roaring and buzzing ), and adjacent areas causes
vertigo and a sensation of unsteadiness.
• Unilateral destruction of the Auditory cortex lead to difficulty in sound
localisation and a bilateral decrease of auditory acuity.
• Bilateral disease lead to Cortical deafness (may be unaware of their
deficits).
• Audiometric tests may be helpful to reveal mild deficits.
• Involvement of vestibular areas may cause difficulty in equillibrium and
imbalance

50. Asymmetry of Temporal lobe function
• Damage to left temporal lobe – deficits in verbal memory, processing
speech sounds
• Damage to right temporal lobe – deficits in nonverbal memory
processing certain aspects of music
face recognition

51. TESTING OF TEMPORAL LOBE

53. Dichotic listening task

54. TESTS FOR VISUAL PROCESSING

55. Verbal memory
• Revised Wechsler Memory Scale- seven subtests:
Spatial Addition, Symbol Span, Design Memory, General
Cognitive Screener, Logical Memory(I & II), Verbal Paired
Associates(I & II), and Visual Reproduction(I & II).
• A person's performance is reported as five Index Scores:
Auditory Memory, Visual Memory, Visual Working Memory,
Immediate Memory, and Delayed Memory

56. Non verbal memory
Rey Complex Figure

57. Non verbal memory (e.g.,)

59. TEMPORAL LOBE SYNDROMES
Homonymous upper
quadrantanopia
Wernicke’s aphasia
Amusia
Anomia
Visual agnosia
Impairment on tests of
visually presented
material
Homonymous upper
quadrantanopia
Agnosia for sounds &
some qualities of music
Impairment on tests of
visually presented
material
U/L disease of dominant lobe U/L disease of nondominant lobe

60. TEMPORAL LOBE SYNDROMES
Auditory, visual, olfactory
& gustatory hallucinations
Dreamy states
Emotional & behavioural
changes
Delirium
Disturbance of time
perception
Korsakoff amnesic defect
Apathy & palcidity
Hypermetamorphopsia,
hyperorality, hypersexulaity,
blunted emotional reactivity
(Kluver-Bucy syndrome)
Either temporal lobe Bilateral disease

61. Wernickes Aphasia
• Also known as Fluent / Recepetive / Sensory / Postrolandic Aphasia
• Due to destruction of posterior superior temporal area of the dominant
hemisphere supplied by inferior division of MCA.
– Fluency is preserved with a normal or even increased word
output (LOGORRHEA)
– Speech although effortless is devoid of meaningful content
– Paraphasias, Neologisms and defective sentence structure
(PARAGRAMMATISM) (JARGON APHASIA)
– Auditory comprehension is impaired, even unaware of his own
speech, and doesnot correct himself.
– Repetition impaired
– Reading impaired
– Naming impaired
– Writing impaired
– Patient often is unaware of the defect

62. Temporal lobe epilepsy / psychomotor seizures
• Patients with Temporal lobe lesion may have visual hallucinations and
perversions.
• Visual hallucinations are complex with image distortion (macropsia /
micropsia / near / far )
• May have an auditory component
• Lesions involving medial temporal lobe in the region of Uncus ( so also k/a
UNCINATE FITS which involve olfactory hallucination also)
• Seizures may present as : automatisms, illusions and hallucinations , and
pilomotor erections.
• Amnesia for the event is usually seen.
• DÉJÀ VU ( already seen), JAMAIS VU (something familiar is strange or
new), DEJA PENSEE/ DEJA VACU ( something new seeming strangely
familiar) , EXPERIENTIAL HALLUCINATIONS (Hallucinations based on
remembered experiences)

63. KLUVER- BUCY SYNDROME
• Experimentally due to bilateral ablation of temporal lobes in monkeys.
• Placidity i.e. extreme calmness
• Lack the ability to visually recognize objects.
• Striking tendency to put everything into mouth.
• Hypersexuality
• Increased food intake
• Seen only in partial forms in humans ( placidity and enhanced oral
behavior are the most common presentations)

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