Sex Differences in the Neurocognition of Language Michael T. Ullman, Ivy V. Estabrooke, Karsten Steinhauer, Claudia Brovetto

Language Processing Language Processing depends on 2 neurocognitive systems Language Processing depends on 2 neurocognitive systems Temporal-lobe based declarative memory system Temporal-lobe based declarative memory system Includes… Includes… Mental lexicon, which contains idiosyncratic word-specific information Mental lexicon, which contains idiosyncratic word-specific information E.g. for irregular past tense; break-broke E.g. for irregular past tense; break-broke Frontal/basal-ganglia procedural system Frontal/basal-ganglia procedural system Includes… Includes… Mental grammar underlying the real-time rule-based composition of complex linguistic representation Mental grammar underlying the real-time rule-based composition of complex linguistic representation E.g. regular past tenses; play + ed E.g. regular past tenses; play + ed Also used in motor skills Also used in motor skills

Females are better than males at remembering words Females are better than males at remembering words Females tend to memorize previously encountered complex representations Females tend to memorize previously encountered complex representations E.g. regular past-tenses; played E.g. regular past-tenses; played Males generally compose it on-line Males generally compose it on-line E.g. play + -ed E.g. play + -ed

Prediction… Both sexes should memorize idiosyncratic lexical knowledge Both sexes should memorize idiosyncratic lexical knowledge E.g. break-broke E.g. break-broke Both should rule compute new complex forms Both should rule compute new complex forms E.g. proy-ed E.g. proy-ed Why? Why? Because these could not be memorized Because these could not be memorized

Previous studies Frequency Effects Frequency Effects Hypothesis: if past-tense representations are retrieved from memory, more frequent ones should be remembered faster. If they are rule products, such past-tense frequency effects are not expected Hypothesis: if past-tense representations are retrieved from memory, more frequent ones should be remembered faster. If they are rule products, such past-tense frequency effects are not expected 16 men and 17 women produced regular/irregular past tenses 16 men and 17 women produced regular/irregular past tenses DV: reaction-time DV: reaction-time Men showed past tense frequency effects for irregulars but not regulars Men showed past tense frequency effects for irregulars but not regulars Women showed past tense frequency effects for both verb types Women showed past tense frequency effects for both verb types Same results for both English and Spanish Same results for both English and Spanish

Parkinson’s Disease Parkinson’s Disease Associated with the Basal-ganglia degeneration leading to hypokinesia (suppressed movement) Associated with the Basal-ganglia degeneration leading to hypokinesia (suppressed movement) Study: 15 men and 14 women with Parkinson’s disease produced past tenses Study: 15 men and 14 women with Parkinson’s disease produced past tenses For men, past-tense production rates of regulars but not irregulars correlated with hypokinesia and production rates for irregulars but not regulars correlated with lexical abilities (object naming) For men, past-tense production rates of regulars but not irregulars correlated with hypokinesia and production rates for irregulars but not regulars correlated with lexical abilities (object naming) For women, production rate for both past-tense types correlated with lexical abilities but not hypokinesia For women, production rate for both past-tense types correlated with lexical abilities but not hypokinesia Most hypokinetic males were impaired only at regulars Most hypokinetic males were impaired only at regulars Most hypokinetic women were impaired at neither Most hypokinetic women were impaired at neither

The Effect of Sex Hormones on Language Processing Ivy V. Estabrooke, Kristen Mordecai, Pauline Maki, and Michale T. Ullman As stated before, women are better than men at remembering words As stated before, women are better than men at remembering words This advantage appears to depend upon the temporal-lobe declarative memory system This advantage appears to depend upon the temporal-lobe declarative memory system Hypothesis: Because of women’s superior lexical/declarative memory ability, girls and women may tend to memorize and/or retrieve at least certain complex representations that men composed on-line Hypothesis: Because of women’s superior lexical/declarative memory ability, girls and women may tend to memorize and/or retrieve at least certain complex representations that men composed on-line

From this, two questions arise From this, two questions arise 1. Do females memorize complex forms at a higher rate than males and/or do both sexes store tense forms, while females have superior lexical retrieval/processing abilities 1. Do females memorize complex forms at a higher rate than males and/or do both sexes store tense forms, while females have superior lexical retrieval/processing abilities 2. Do sex hormones, and estrogen in particular, contribute to the sex differences? 2. Do sex hormones, and estrogen in particular, contribute to the sex differences? Previous data supports this hypothesis Previous data supports this hypothesis Estrogen improves word and declarative memory abilities in women; more over, this improvement depends on the part of the temporal lobe that underlies declarative memory Estrogen improves word and declarative memory abilities in women; more over, this improvement depends on the part of the temporal lobe that underlies declarative memory Furthermore, testosterone improves men’s word memory Furthermore, testosterone improves men’s word memory

Methods 10 post-menopausal women and 12 age-matched men participate in study of the effects of hormone therapy on language processing 10 post-menopausal women and 12 age-matched men participate in study of the effects of hormone therapy on language processing Subjects were given hormone replacement therapy Subjects were given hormone replacement therapy Women-estrogen, Men-testosterone, and placebo group Women-estrogen, Men-testosterone, and placebo group After each three months, subjects were given past-tense production task containing… After each three months, subjects were given past-tense production task containing… Regular (sway-swayed), irregular (break-broke), novel regular (plag- plagged) and novel irregular (spling-splung) Regular (sway-swayed), irregular (break-broke), novel regular (plag- plagged) and novel irregular (spling-splung) Verbs were presented in sentence contexts Verbs were presented in sentence contexts E.g. Every day I sleep in bed. Yesterday, I ________ in bed. E.g. Every day I sleep in bed. Yesterday, I ________ in bed. Accuracy was the DV Accuracy was the DV

Results Hormone therapy yielded increased estrogen levels in both sexes Hormone therapy yielded increased estrogen levels in both sexes It also induced an increase in both sexes in the production rate of real and novel irregular past tenses It also induced an increase in both sexes in the production rate of real and novel irregular past tenses Performance at novel regulars decreased with hormone therapy in both sexes Performance at novel regulars decreased with hormone therapy in both sexes Likely due to an increased irregularizations (plag-plog) Likely due to an increased irregularizations (plag-plog) Accuracy at real regulars INCREASED in women but DECREASED in men, as a result of hormone therapy Accuracy at real regulars INCREASED in women but DECREASED in men, as a result of hormone therapy

Accuracy at Past Tense Production

Analysis Increase in both women and men in production rate of real/novel irregular past-tense forms suggests that sex hormones improve the retrieval/processing of existing memorized lexical representations Increase in both women and men in production rate of real/novel irregular past-tense forms suggests that sex hormones improve the retrieval/processing of existing memorized lexical representations And of novel forms whose processing depends on preexisting similar memory traces And of novel forms whose processing depends on preexisting similar memory traces E.g. fling-flung, wring-wrung E.g. fling-flung, wring-wrung

The decrease in performance of novel regulars with hormone therapy in both sexes.. The decrease in performance of novel regulars with hormone therapy in both sexes.. Supports view that these forms are computed by neural mechanisms distinct from those that underlie the processing of real and novel irregulars Supports view that these forms are computed by neural mechanisms distinct from those that underlie the processing of real and novel irregulars It also supports the dual-system “declarative/procedural model” It also supports the dual-system “declarative/procedural model”

The fact that hormone therapy led to an increase in the production rate of regular past-tenses in women, but a decrease in men shows that in women these forms patttern with the mempry- dependent irregulars and in men, they pattern with the compositional novel regulars The fact that hormone therapy led to an increase in the production rate of regular past-tenses in women, but a decrease in men shows that in women these forms patttern with the mempry- dependent irregulars and in men, they pattern with the compositional novel regulars

Conclusion The sex differences just observed may be attributable to the prior memorization of complex forms by girls The sex differences just observed may be attributable to the prior memorization of complex forms by girls This may be explained by sex-differences in estrogen levels, which could affect brain organization in utero and or learning during childhood This may be explained by sex-differences in estrogen levels, which could affect brain organization in utero and or learning during childhood